2 * Base port operations for 8250/16550-type serial ports
4 * Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
5 * Split from 8250_core.c, Copyright (C) 2001 Russell King.
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
12 * A note about mapbase / membase
14 * mapbase is the physical address of the IO port.
15 * membase is an 'ioremapped' cookie.
18 #if defined(CONFIG_SERIAL_8250_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
22 #include <linux/module.h>
23 #include <linux/moduleparam.h>
24 #include <linux/ioport.h>
25 #include <linux/init.h>
26 #include <linux/console.h>
27 #include <linux/sysrq.h>
28 #include <linux/delay.h>
29 #include <linux/platform_device.h>
30 #include <linux/tty.h>
31 #include <linux/ratelimit.h>
32 #include <linux/tty_flip.h>
33 #include <linux/serial.h>
34 #include <linux/serial_8250.h>
35 #include <linux/nmi.h>
36 #include <linux/mutex.h>
37 #include <linux/slab.h>
38 #include <linux/uaccess.h>
39 #include <linux/pm_runtime.h>
40 #include <linux/ktime.h>
48 * These are definitions for the Exar XR17V35X and XR17(C|D)15X
50 #define UART_EXAR_INT0 0x80
51 #define UART_EXAR_SLEEP 0x8b /* Sleep mode */
52 #define UART_EXAR_DVID 0x8d /* Device identification */
54 /* Nuvoton NPCM timeout register */
55 #define UART_NPCM_TOR 7
56 #define UART_NPCM_TOIE BIT(7) /* Timeout Interrupt Enable */
62 #define DEBUG_AUTOCONF(fmt...) printk(fmt)
64 #define DEBUG_AUTOCONF(fmt...) do { } while (0)
67 #define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE)
70 * Here we define the default xmit fifo size used for each type of UART.
72 static const struct serial8250_config uart_config[] = {
97 .fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10,
98 .rxtrig_bytes = {1, 4, 8, 14},
99 .flags = UART_CAP_FIFO,
110 .flags = UART_CAP_FIFO | UART_CAP_EFR | UART_CAP_SLEEP,
116 .fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_01 |
118 .rxtrig_bytes = {8, 16, 24, 28},
119 .flags = UART_CAP_FIFO | UART_CAP_EFR | UART_CAP_SLEEP,
125 .fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10 |
127 .rxtrig_bytes = {1, 16, 32, 56},
128 .flags = UART_CAP_FIFO | UART_CAP_SLEEP | UART_CAP_AFE,
136 .name = "16C950/954",
139 .fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_01,
140 .rxtrig_bytes = {16, 32, 112, 120},
141 /* UART_CAP_EFR breaks billionon CF bluetooth card. */
142 .flags = UART_CAP_FIFO | UART_CAP_SLEEP,
148 .fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_01 |
150 .rxtrig_bytes = {8, 16, 56, 60},
151 .flags = UART_CAP_FIFO | UART_CAP_EFR | UART_CAP_SLEEP,
157 .fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10,
158 .flags = UART_CAP_FIFO | UART_CAP_EFR | UART_CAP_SLEEP,
164 .fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_11,
165 .flags = UART_CAP_FIFO,
171 .fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10,
172 .flags = UART_CAP_FIFO | UART_NATSEMI,
178 .fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10,
179 .flags = UART_CAP_FIFO | UART_CAP_UUE | UART_CAP_RTOIE,
185 .fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10,
186 .flags = UART_CAP_FIFO,
192 .fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_00,
193 .flags = UART_CAP_FIFO /* | UART_CAP_AFE */,
199 .fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10,
200 .flags = UART_CAP_FIFO | UART_CAP_AFE,
206 .fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_01 |
208 .rxtrig_bytes = {1, 4, 8, 14},
209 .flags = UART_CAP_FIFO | UART_CAP_RTOIE,
215 .fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10,
216 .flags = UART_CAP_FIFO | UART_CAP_AFE | UART_CAP_EFR |
223 .fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_11 |
225 .flags = UART_CAP_FIFO | UART_CAP_AFE | UART_CAP_EFR |
232 .fcr = UART_FCR_DMA_SELECT | UART_FCR_ENABLE_FIFO |
233 UART_FCR_R_TRIG_00 | UART_FCR_T_TRIG_00,
234 .flags = UART_CAP_FIFO,
236 [PORT_BRCM_TRUMANAGE] = {
240 .flags = UART_CAP_HFIFO,
245 [PORT_ALTR_16550_F32] = {
246 .name = "Altera 16550 FIFO32",
249 .fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10,
250 .flags = UART_CAP_FIFO | UART_CAP_AFE,
252 [PORT_ALTR_16550_F64] = {
253 .name = "Altera 16550 FIFO64",
256 .fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10,
257 .flags = UART_CAP_FIFO | UART_CAP_AFE,
259 [PORT_ALTR_16550_F128] = {
260 .name = "Altera 16550 FIFO128",
263 .fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10,
264 .flags = UART_CAP_FIFO | UART_CAP_AFE,
267 * tx_loadsz is set to 63-bytes instead of 64-bytes to implement
268 * workaround of errata A-008006 which states that tx_loadsz should
269 * be configured less than Maximum supported fifo bytes.
271 [PORT_16550A_FSL64] = {
272 .name = "16550A_FSL64",
275 .fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10 |
277 .flags = UART_CAP_FIFO,
280 .name = "Palmchip BK-3103",
283 .fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10,
284 .rxtrig_bytes = {1, 4, 8, 14},
285 .flags = UART_CAP_FIFO,
288 .name = "TI DA8xx/66AK2x",
291 .fcr = UART_FCR_DMA_SELECT | UART_FCR_ENABLE_FIFO |
293 .rxtrig_bytes = {1, 4, 8, 14},
294 .flags = UART_CAP_FIFO | UART_CAP_AFE,
297 .name = "MediaTek BTIF",
300 .fcr = UART_FCR_ENABLE_FIFO |
301 UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT,
302 .flags = UART_CAP_FIFO,
305 .name = "Nuvoton 16550",
308 .fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10 |
309 UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT,
310 .rxtrig_bytes = {1, 4, 8, 14},
311 .flags = UART_CAP_FIFO,
315 /* Uart divisor latch read */
316 static int default_serial_dl_read(struct uart_8250_port *up)
318 /* Assign these in pieces to truncate any bits above 7. */
319 unsigned char dll = serial_in(up, UART_DLL);
320 unsigned char dlm = serial_in(up, UART_DLM);
322 return dll | dlm << 8;
325 /* Uart divisor latch write */
326 static void default_serial_dl_write(struct uart_8250_port *up, int value)
328 serial_out(up, UART_DLL, value & 0xff);
329 serial_out(up, UART_DLM, value >> 8 & 0xff);
332 #ifdef CONFIG_SERIAL_8250_RT288X
334 /* Au1x00/RT288x UART hardware has a weird register layout */
335 static const s8 au_io_in_map[8] = {
343 -1, /* UART_SCR (unmapped) */
346 static const s8 au_io_out_map[8] = {
352 -1, /* UART_LSR (unmapped) */
353 -1, /* UART_MSR (unmapped) */
354 -1, /* UART_SCR (unmapped) */
357 unsigned int au_serial_in(struct uart_port *p, int offset)
359 if (offset >= ARRAY_SIZE(au_io_in_map))
361 offset = au_io_in_map[offset];
364 return __raw_readl(p->membase + (offset << p->regshift));
367 void au_serial_out(struct uart_port *p, int offset, int value)
369 if (offset >= ARRAY_SIZE(au_io_out_map))
371 offset = au_io_out_map[offset];
374 __raw_writel(value, p->membase + (offset << p->regshift));
377 /* Au1x00 haven't got a standard divisor latch */
378 static int au_serial_dl_read(struct uart_8250_port *up)
380 return __raw_readl(up->port.membase + 0x28);
383 static void au_serial_dl_write(struct uart_8250_port *up, int value)
385 __raw_writel(value, up->port.membase + 0x28);
390 static unsigned int hub6_serial_in(struct uart_port *p, int offset)
392 offset = offset << p->regshift;
393 outb(p->hub6 - 1 + offset, p->iobase);
394 return inb(p->iobase + 1);
397 static void hub6_serial_out(struct uart_port *p, int offset, int value)
399 offset = offset << p->regshift;
400 outb(p->hub6 - 1 + offset, p->iobase);
401 outb(value, p->iobase + 1);
404 static unsigned int mem_serial_in(struct uart_port *p, int offset)
406 offset = offset << p->regshift;
407 return readb(p->membase + offset);
410 static void mem_serial_out(struct uart_port *p, int offset, int value)
412 offset = offset << p->regshift;
413 writeb(value, p->membase + offset);
416 static void mem16_serial_out(struct uart_port *p, int offset, int value)
418 offset = offset << p->regshift;
419 writew(value, p->membase + offset);
422 static unsigned int mem16_serial_in(struct uart_port *p, int offset)
424 offset = offset << p->regshift;
425 return readw(p->membase + offset);
428 static void mem32_serial_out(struct uart_port *p, int offset, int value)
430 offset = offset << p->regshift;
431 writel(value, p->membase + offset);
434 static unsigned int mem32_serial_in(struct uart_port *p, int offset)
436 offset = offset << p->regshift;
437 return readl(p->membase + offset);
440 static void mem32be_serial_out(struct uart_port *p, int offset, int value)
442 offset = offset << p->regshift;
443 iowrite32be(value, p->membase + offset);
446 static unsigned int mem32be_serial_in(struct uart_port *p, int offset)
448 offset = offset << p->regshift;
449 return ioread32be(p->membase + offset);
452 static unsigned int io_serial_in(struct uart_port *p, int offset)
454 offset = offset << p->regshift;
455 return inb(p->iobase + offset);
458 static void io_serial_out(struct uart_port *p, int offset, int value)
460 offset = offset << p->regshift;
461 outb(value, p->iobase + offset);
464 static int serial8250_default_handle_irq(struct uart_port *port);
466 static void set_io_from_upio(struct uart_port *p)
468 struct uart_8250_port *up = up_to_u8250p(p);
470 up->dl_read = default_serial_dl_read;
471 up->dl_write = default_serial_dl_write;
475 p->serial_in = hub6_serial_in;
476 p->serial_out = hub6_serial_out;
480 p->serial_in = mem_serial_in;
481 p->serial_out = mem_serial_out;
485 p->serial_in = mem16_serial_in;
486 p->serial_out = mem16_serial_out;
490 p->serial_in = mem32_serial_in;
491 p->serial_out = mem32_serial_out;
495 p->serial_in = mem32be_serial_in;
496 p->serial_out = mem32be_serial_out;
499 #ifdef CONFIG_SERIAL_8250_RT288X
501 p->serial_in = au_serial_in;
502 p->serial_out = au_serial_out;
503 up->dl_read = au_serial_dl_read;
504 up->dl_write = au_serial_dl_write;
509 p->serial_in = io_serial_in;
510 p->serial_out = io_serial_out;
513 /* Remember loaded iotype */
514 up->cur_iotype = p->iotype;
515 p->handle_irq = serial8250_default_handle_irq;
519 serial_port_out_sync(struct uart_port *p, int offset, int value)
527 p->serial_out(p, offset, value);
528 p->serial_in(p, UART_LCR); /* safe, no side-effects */
531 p->serial_out(p, offset, value);
538 static void serial_icr_write(struct uart_8250_port *up, int offset, int value)
540 serial_out(up, UART_SCR, offset);
541 serial_out(up, UART_ICR, value);
544 static unsigned int serial_icr_read(struct uart_8250_port *up, int offset)
548 serial_icr_write(up, UART_ACR, up->acr | UART_ACR_ICRRD);
549 serial_out(up, UART_SCR, offset);
550 value = serial_in(up, UART_ICR);
551 serial_icr_write(up, UART_ACR, up->acr);
559 static void serial8250_clear_fifos(struct uart_8250_port *p)
561 if (p->capabilities & UART_CAP_FIFO) {
562 serial_out(p, UART_FCR, UART_FCR_ENABLE_FIFO);
563 serial_out(p, UART_FCR, UART_FCR_ENABLE_FIFO |
564 UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT);
565 serial_out(p, UART_FCR, 0);
569 static inline void serial8250_em485_rts_after_send(struct uart_8250_port *p)
571 unsigned char mcr = serial8250_in_MCR(p);
573 if (p->port.rs485.flags & SER_RS485_RTS_AFTER_SEND)
576 mcr &= ~UART_MCR_RTS;
577 serial8250_out_MCR(p, mcr);
580 static enum hrtimer_restart serial8250_em485_handle_start_tx(struct hrtimer *t);
581 static enum hrtimer_restart serial8250_em485_handle_stop_tx(struct hrtimer *t);
583 void serial8250_clear_and_reinit_fifos(struct uart_8250_port *p)
585 serial8250_clear_fifos(p);
586 serial_out(p, UART_FCR, p->fcr);
588 EXPORT_SYMBOL_GPL(serial8250_clear_and_reinit_fifos);
590 void serial8250_rpm_get(struct uart_8250_port *p)
592 if (!(p->capabilities & UART_CAP_RPM))
594 pm_runtime_get_sync(p->port.dev);
596 EXPORT_SYMBOL_GPL(serial8250_rpm_get);
598 void serial8250_rpm_put(struct uart_8250_port *p)
600 if (!(p->capabilities & UART_CAP_RPM))
602 pm_runtime_mark_last_busy(p->port.dev);
603 pm_runtime_put_autosuspend(p->port.dev);
605 EXPORT_SYMBOL_GPL(serial8250_rpm_put);
608 * serial8250_em485_init() - put uart_8250_port into rs485 emulating
609 * @p: uart_8250_port port instance
611 * The function is used to start rs485 software emulating on the
612 * &struct uart_8250_port* @p. Namely, RTS is switched before/after
613 * transmission. The function is idempotent, so it is safe to call it
616 * The caller MUST enable interrupt on empty shift register before
617 * calling serial8250_em485_init(). This interrupt is not a part of
618 * 8250 standard, but implementation defined.
620 * The function is supposed to be called from .rs485_config callback
621 * or from any other callback protected with p->port.lock spinlock.
623 * See also serial8250_em485_destroy()
625 * Return 0 - success, -errno - otherwise
627 int serial8250_em485_init(struct uart_8250_port *p)
632 p->em485 = kmalloc(sizeof(struct uart_8250_em485), GFP_ATOMIC);
636 hrtimer_init(&p->em485->stop_tx_timer, CLOCK_MONOTONIC,
638 hrtimer_init(&p->em485->start_tx_timer, CLOCK_MONOTONIC,
640 p->em485->stop_tx_timer.function = &serial8250_em485_handle_stop_tx;
641 p->em485->start_tx_timer.function = &serial8250_em485_handle_start_tx;
643 p->em485->active_timer = NULL;
644 serial8250_em485_rts_after_send(p);
648 EXPORT_SYMBOL_GPL(serial8250_em485_init);
651 * serial8250_em485_destroy() - put uart_8250_port into normal state
652 * @p: uart_8250_port port instance
654 * The function is used to stop rs485 software emulating on the
655 * &struct uart_8250_port* @p. The function is idempotent, so it is safe to
656 * call it multiple times.
658 * The function is supposed to be called from .rs485_config callback
659 * or from any other callback protected with p->port.lock spinlock.
661 * See also serial8250_em485_init()
663 void serial8250_em485_destroy(struct uart_8250_port *p)
668 hrtimer_cancel(&p->em485->start_tx_timer);
669 hrtimer_cancel(&p->em485->stop_tx_timer);
674 EXPORT_SYMBOL_GPL(serial8250_em485_destroy);
677 * These two wrappers ensure that enable_runtime_pm_tx() can be called more than
678 * once and disable_runtime_pm_tx() will still disable RPM because the fifo is
679 * empty and the HW can idle again.
681 void serial8250_rpm_get_tx(struct uart_8250_port *p)
683 unsigned char rpm_active;
685 if (!(p->capabilities & UART_CAP_RPM))
688 rpm_active = xchg(&p->rpm_tx_active, 1);
691 pm_runtime_get_sync(p->port.dev);
693 EXPORT_SYMBOL_GPL(serial8250_rpm_get_tx);
695 void serial8250_rpm_put_tx(struct uart_8250_port *p)
697 unsigned char rpm_active;
699 if (!(p->capabilities & UART_CAP_RPM))
702 rpm_active = xchg(&p->rpm_tx_active, 0);
705 pm_runtime_mark_last_busy(p->port.dev);
706 pm_runtime_put_autosuspend(p->port.dev);
708 EXPORT_SYMBOL_GPL(serial8250_rpm_put_tx);
711 * IER sleep support. UARTs which have EFRs need the "extended
712 * capability" bit enabled. Note that on XR16C850s, we need to
713 * reset LCR to write to IER.
715 static void serial8250_set_sleep(struct uart_8250_port *p, int sleep)
717 unsigned char lcr = 0, efr = 0;
719 * Exar UARTs have a SLEEP register that enables or disables
720 * each UART to enter sleep mode separately. On the XR17V35x the
721 * register is accessible to each UART at the UART_EXAR_SLEEP
722 * offset but the UART channel may only write to the corresponding
725 serial8250_rpm_get(p);
726 if ((p->port.type == PORT_XR17V35X) ||
727 (p->port.type == PORT_XR17D15X)) {
728 serial_out(p, UART_EXAR_SLEEP, sleep ? 0xff : 0);
732 if (p->capabilities & UART_CAP_SLEEP) {
733 if (p->capabilities & UART_CAP_EFR) {
734 lcr = serial_in(p, UART_LCR);
735 efr = serial_in(p, UART_EFR);
736 serial_out(p, UART_LCR, UART_LCR_CONF_MODE_B);
737 serial_out(p, UART_EFR, UART_EFR_ECB);
738 serial_out(p, UART_LCR, 0);
740 serial_out(p, UART_IER, sleep ? UART_IERX_SLEEP : 0);
741 if (p->capabilities & UART_CAP_EFR) {
742 serial_out(p, UART_LCR, UART_LCR_CONF_MODE_B);
743 serial_out(p, UART_EFR, efr);
744 serial_out(p, UART_LCR, lcr);
748 serial8250_rpm_put(p);
751 #ifdef CONFIG_SERIAL_8250_RSA
753 * Attempts to turn on the RSA FIFO. Returns zero on failure.
754 * We set the port uart clock rate if we succeed.
756 static int __enable_rsa(struct uart_8250_port *up)
761 mode = serial_in(up, UART_RSA_MSR);
762 result = mode & UART_RSA_MSR_FIFO;
765 serial_out(up, UART_RSA_MSR, mode | UART_RSA_MSR_FIFO);
766 mode = serial_in(up, UART_RSA_MSR);
767 result = mode & UART_RSA_MSR_FIFO;
771 up->port.uartclk = SERIAL_RSA_BAUD_BASE * 16;
776 static void enable_rsa(struct uart_8250_port *up)
778 if (up->port.type == PORT_RSA) {
779 if (up->port.uartclk != SERIAL_RSA_BAUD_BASE * 16) {
780 spin_lock_irq(&up->port.lock);
782 spin_unlock_irq(&up->port.lock);
784 if (up->port.uartclk == SERIAL_RSA_BAUD_BASE * 16)
785 serial_out(up, UART_RSA_FRR, 0);
790 * Attempts to turn off the RSA FIFO. Returns zero on failure.
791 * It is unknown why interrupts were disabled in here. However,
792 * the caller is expected to preserve this behaviour by grabbing
793 * the spinlock before calling this function.
795 static void disable_rsa(struct uart_8250_port *up)
800 if (up->port.type == PORT_RSA &&
801 up->port.uartclk == SERIAL_RSA_BAUD_BASE * 16) {
802 spin_lock_irq(&up->port.lock);
804 mode = serial_in(up, UART_RSA_MSR);
805 result = !(mode & UART_RSA_MSR_FIFO);
808 serial_out(up, UART_RSA_MSR, mode & ~UART_RSA_MSR_FIFO);
809 mode = serial_in(up, UART_RSA_MSR);
810 result = !(mode & UART_RSA_MSR_FIFO);
814 up->port.uartclk = SERIAL_RSA_BAUD_BASE_LO * 16;
815 spin_unlock_irq(&up->port.lock);
818 #endif /* CONFIG_SERIAL_8250_RSA */
821 * This is a quickie test to see how big the FIFO is.
822 * It doesn't work at all the time, more's the pity.
824 static int size_fifo(struct uart_8250_port *up)
826 unsigned char old_fcr, old_mcr, old_lcr;
827 unsigned short old_dl;
830 old_lcr = serial_in(up, UART_LCR);
831 serial_out(up, UART_LCR, 0);
832 old_fcr = serial_in(up, UART_FCR);
833 old_mcr = serial8250_in_MCR(up);
834 serial_out(up, UART_FCR, UART_FCR_ENABLE_FIFO |
835 UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT);
836 serial8250_out_MCR(up, UART_MCR_LOOP);
837 serial_out(up, UART_LCR, UART_LCR_CONF_MODE_A);
838 old_dl = serial_dl_read(up);
839 serial_dl_write(up, 0x0001);
840 serial_out(up, UART_LCR, 0x03);
841 for (count = 0; count < 256; count++)
842 serial_out(up, UART_TX, count);
843 mdelay(20);/* FIXME - schedule_timeout */
844 for (count = 0; (serial_in(up, UART_LSR) & UART_LSR_DR) &&
845 (count < 256); count++)
846 serial_in(up, UART_RX);
847 serial_out(up, UART_FCR, old_fcr);
848 serial8250_out_MCR(up, old_mcr);
849 serial_out(up, UART_LCR, UART_LCR_CONF_MODE_A);
850 serial_dl_write(up, old_dl);
851 serial_out(up, UART_LCR, old_lcr);
857 * Read UART ID using the divisor method - set DLL and DLM to zero
858 * and the revision will be in DLL and device type in DLM. We
859 * preserve the device state across this.
861 static unsigned int autoconfig_read_divisor_id(struct uart_8250_port *p)
863 unsigned char old_lcr;
864 unsigned int id, old_dl;
866 old_lcr = serial_in(p, UART_LCR);
867 serial_out(p, UART_LCR, UART_LCR_CONF_MODE_A);
868 old_dl = serial_dl_read(p);
869 serial_dl_write(p, 0);
870 id = serial_dl_read(p);
871 serial_dl_write(p, old_dl);
873 serial_out(p, UART_LCR, old_lcr);
879 * This is a helper routine to autodetect StarTech/Exar/Oxsemi UART's.
880 * When this function is called we know it is at least a StarTech
881 * 16650 V2, but it might be one of several StarTech UARTs, or one of
882 * its clones. (We treat the broken original StarTech 16650 V1 as a
883 * 16550, and why not? Startech doesn't seem to even acknowledge its
886 * What evil have men's minds wrought...
888 static void autoconfig_has_efr(struct uart_8250_port *up)
890 unsigned int id1, id2, id3, rev;
893 * Everything with an EFR has SLEEP
895 up->capabilities |= UART_CAP_EFR | UART_CAP_SLEEP;
898 * First we check to see if it's an Oxford Semiconductor UART.
900 * If we have to do this here because some non-National
901 * Semiconductor clone chips lock up if you try writing to the
902 * LSR register (which serial_icr_read does)
906 * Check for Oxford Semiconductor 16C950.
908 * EFR [4] must be set else this test fails.
910 * This shouldn't be necessary, but Mike Hudson (Exoray@isys.ca)
911 * claims that it's needed for 952 dual UART's (which are not
912 * recommended for new designs).
915 serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
916 serial_out(up, UART_EFR, UART_EFR_ECB);
917 serial_out(up, UART_LCR, 0x00);
918 id1 = serial_icr_read(up, UART_ID1);
919 id2 = serial_icr_read(up, UART_ID2);
920 id3 = serial_icr_read(up, UART_ID3);
921 rev = serial_icr_read(up, UART_REV);
923 DEBUG_AUTOCONF("950id=%02x:%02x:%02x:%02x ", id1, id2, id3, rev);
925 if (id1 == 0x16 && id2 == 0xC9 &&
926 (id3 == 0x50 || id3 == 0x52 || id3 == 0x54)) {
927 up->port.type = PORT_16C950;
930 * Enable work around for the Oxford Semiconductor 952 rev B
931 * chip which causes it to seriously miscalculate baud rates
934 if (id3 == 0x52 && rev == 0x01)
935 up->bugs |= UART_BUG_QUOT;
940 * We check for a XR16C850 by setting DLL and DLM to 0, and then
941 * reading back DLL and DLM. The chip type depends on the DLM
943 * 0x10 - XR16C850 and the DLL contains the chip revision.
947 id1 = autoconfig_read_divisor_id(up);
948 DEBUG_AUTOCONF("850id=%04x ", id1);
951 if (id2 == 0x10 || id2 == 0x12 || id2 == 0x14) {
952 up->port.type = PORT_16850;
957 * It wasn't an XR16C850.
959 * We distinguish between the '654 and the '650 by counting
960 * how many bytes are in the FIFO. I'm using this for now,
961 * since that's the technique that was sent to me in the
962 * serial driver update, but I'm not convinced this works.
963 * I've had problems doing this in the past. -TYT
965 if (size_fifo(up) == 64)
966 up->port.type = PORT_16654;
968 up->port.type = PORT_16650V2;
972 * We detected a chip without a FIFO. Only two fall into
973 * this category - the original 8250 and the 16450. The
974 * 16450 has a scratch register (accessible with LCR=0)
976 static void autoconfig_8250(struct uart_8250_port *up)
978 unsigned char scratch, status1, status2;
980 up->port.type = PORT_8250;
982 scratch = serial_in(up, UART_SCR);
983 serial_out(up, UART_SCR, 0xa5);
984 status1 = serial_in(up, UART_SCR);
985 serial_out(up, UART_SCR, 0x5a);
986 status2 = serial_in(up, UART_SCR);
987 serial_out(up, UART_SCR, scratch);
989 if (status1 == 0xa5 && status2 == 0x5a)
990 up->port.type = PORT_16450;
993 static int broken_efr(struct uart_8250_port *up)
996 * Exar ST16C2550 "A2" devices incorrectly detect as
997 * having an EFR, and report an ID of 0x0201. See
998 * http://linux.derkeiler.com/Mailing-Lists/Kernel/2004-11/4812.html
1000 if (autoconfig_read_divisor_id(up) == 0x0201 && size_fifo(up) == 16)
1007 * We know that the chip has FIFOs. Does it have an EFR? The
1008 * EFR is located in the same register position as the IIR and
1009 * we know the top two bits of the IIR are currently set. The
1010 * EFR should contain zero. Try to read the EFR.
1012 static void autoconfig_16550a(struct uart_8250_port *up)
1014 unsigned char status1, status2;
1015 unsigned int iersave;
1017 up->port.type = PORT_16550A;
1018 up->capabilities |= UART_CAP_FIFO;
1021 * XR17V35x UARTs have an extra divisor register, DLD
1022 * that gets enabled with when DLAB is set which will
1023 * cause the device to incorrectly match and assign
1024 * port type to PORT_16650. The EFR for this UART is
1025 * found at offset 0x09. Instead check the Deice ID (DVID)
1026 * register for a 2, 4 or 8 port UART.
1028 if (up->port.flags & UPF_EXAR_EFR) {
1029 status1 = serial_in(up, UART_EXAR_DVID);
1030 if (status1 == 0x82 || status1 == 0x84 || status1 == 0x88) {
1031 DEBUG_AUTOCONF("Exar XR17V35x ");
1032 up->port.type = PORT_XR17V35X;
1033 up->capabilities |= UART_CAP_AFE | UART_CAP_EFR |
1042 * Check for presence of the EFR when DLAB is set.
1043 * Only ST16C650V1 UARTs pass this test.
1045 serial_out(up, UART_LCR, UART_LCR_CONF_MODE_A);
1046 if (serial_in(up, UART_EFR) == 0) {
1047 serial_out(up, UART_EFR, 0xA8);
1048 if (serial_in(up, UART_EFR) != 0) {
1049 DEBUG_AUTOCONF("EFRv1 ");
1050 up->port.type = PORT_16650;
1051 up->capabilities |= UART_CAP_EFR | UART_CAP_SLEEP;
1053 serial_out(up, UART_LCR, 0);
1054 serial_out(up, UART_FCR, UART_FCR_ENABLE_FIFO |
1056 status1 = serial_in(up, UART_IIR) >> 5;
1057 serial_out(up, UART_FCR, 0);
1058 serial_out(up, UART_LCR, 0);
1061 up->port.type = PORT_16550A_FSL64;
1063 DEBUG_AUTOCONF("Motorola 8xxx DUART ");
1065 serial_out(up, UART_EFR, 0);
1070 * Maybe it requires 0xbf to be written to the LCR.
1071 * (other ST16C650V2 UARTs, TI16C752A, etc)
1073 serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
1074 if (serial_in(up, UART_EFR) == 0 && !broken_efr(up)) {
1075 DEBUG_AUTOCONF("EFRv2 ");
1076 autoconfig_has_efr(up);
1081 * Check for a National Semiconductor SuperIO chip.
1082 * Attempt to switch to bank 2, read the value of the LOOP bit
1083 * from EXCR1. Switch back to bank 0, change it in MCR. Then
1084 * switch back to bank 2, read it from EXCR1 again and check
1085 * it's changed. If so, set baud_base in EXCR2 to 921600. -- dwmw2
1087 serial_out(up, UART_LCR, 0);
1088 status1 = serial8250_in_MCR(up);
1089 serial_out(up, UART_LCR, 0xE0);
1090 status2 = serial_in(up, 0x02); /* EXCR1 */
1092 if (!((status2 ^ status1) & UART_MCR_LOOP)) {
1093 serial_out(up, UART_LCR, 0);
1094 serial8250_out_MCR(up, status1 ^ UART_MCR_LOOP);
1095 serial_out(up, UART_LCR, 0xE0);
1096 status2 = serial_in(up, 0x02); /* EXCR1 */
1097 serial_out(up, UART_LCR, 0);
1098 serial8250_out_MCR(up, status1);
1100 if ((status2 ^ status1) & UART_MCR_LOOP) {
1101 unsigned short quot;
1103 serial_out(up, UART_LCR, 0xE0);
1105 quot = serial_dl_read(up);
1108 if (ns16550a_goto_highspeed(up))
1109 serial_dl_write(up, quot);
1111 serial_out(up, UART_LCR, 0);
1113 up->port.uartclk = 921600*16;
1114 up->port.type = PORT_NS16550A;
1115 up->capabilities |= UART_NATSEMI;
1121 * No EFR. Try to detect a TI16750, which only sets bit 5 of
1122 * the IIR when 64 byte FIFO mode is enabled when DLAB is set.
1123 * Try setting it with and without DLAB set. Cheap clones
1124 * set bit 5 without DLAB set.
1126 serial_out(up, UART_LCR, 0);
1127 serial_out(up, UART_FCR, UART_FCR_ENABLE_FIFO | UART_FCR7_64BYTE);
1128 status1 = serial_in(up, UART_IIR) >> 5;
1129 serial_out(up, UART_FCR, UART_FCR_ENABLE_FIFO);
1130 serial_out(up, UART_LCR, UART_LCR_CONF_MODE_A);
1131 serial_out(up, UART_FCR, UART_FCR_ENABLE_FIFO | UART_FCR7_64BYTE);
1132 status2 = serial_in(up, UART_IIR) >> 5;
1133 serial_out(up, UART_FCR, UART_FCR_ENABLE_FIFO);
1134 serial_out(up, UART_LCR, 0);
1136 DEBUG_AUTOCONF("iir1=%d iir2=%d ", status1, status2);
1138 if (status1 == 6 && status2 == 7) {
1139 up->port.type = PORT_16750;
1140 up->capabilities |= UART_CAP_AFE | UART_CAP_SLEEP;
1145 * Try writing and reading the UART_IER_UUE bit (b6).
1146 * If it works, this is probably one of the Xscale platform's
1148 * We're going to explicitly set the UUE bit to 0 before
1149 * trying to write and read a 1 just to make sure it's not
1150 * already a 1 and maybe locked there before we even start start.
1152 iersave = serial_in(up, UART_IER);
1153 serial_out(up, UART_IER, iersave & ~UART_IER_UUE);
1154 if (!(serial_in(up, UART_IER) & UART_IER_UUE)) {
1156 * OK it's in a known zero state, try writing and reading
1157 * without disturbing the current state of the other bits.
1159 serial_out(up, UART_IER, iersave | UART_IER_UUE);
1160 if (serial_in(up, UART_IER) & UART_IER_UUE) {
1163 * We'll leave the UART_IER_UUE bit set to 1 (enabled).
1165 DEBUG_AUTOCONF("Xscale ");
1166 up->port.type = PORT_XSCALE;
1167 up->capabilities |= UART_CAP_UUE | UART_CAP_RTOIE;
1172 * If we got here we couldn't force the IER_UUE bit to 0.
1173 * Log it and continue.
1175 DEBUG_AUTOCONF("Couldn't force IER_UUE to 0 ");
1177 serial_out(up, UART_IER, iersave);
1180 * Exar uarts have EFR in a weird location
1182 if (up->port.flags & UPF_EXAR_EFR) {
1183 DEBUG_AUTOCONF("Exar XR17D15x ");
1184 up->port.type = PORT_XR17D15X;
1185 up->capabilities |= UART_CAP_AFE | UART_CAP_EFR |
1192 * We distinguish between 16550A and U6 16550A by counting
1193 * how many bytes are in the FIFO.
1195 if (up->port.type == PORT_16550A && size_fifo(up) == 64) {
1196 up->port.type = PORT_U6_16550A;
1197 up->capabilities |= UART_CAP_AFE;
1202 * This routine is called by rs_init() to initialize a specific serial
1203 * port. It determines what type of UART chip this serial port is
1204 * using: 8250, 16450, 16550, 16550A. The important question is
1205 * whether or not this UART is a 16550A or not, since this will
1206 * determine whether or not we can use its FIFO features or not.
1208 static void autoconfig(struct uart_8250_port *up)
1210 unsigned char status1, scratch, scratch2, scratch3;
1211 unsigned char save_lcr, save_mcr;
1212 struct uart_port *port = &up->port;
1213 unsigned long flags;
1214 unsigned int old_capabilities;
1216 if (!port->iobase && !port->mapbase && !port->membase)
1219 DEBUG_AUTOCONF("ttyS%d: autoconf (0x%04lx, 0x%p): ",
1220 serial_index(port), port->iobase, port->membase);
1223 * We really do need global IRQs disabled here - we're going to
1224 * be frobbing the chips IRQ enable register to see if it exists.
1226 spin_lock_irqsave(&port->lock, flags);
1228 up->capabilities = 0;
1231 if (!(port->flags & UPF_BUGGY_UART)) {
1233 * Do a simple existence test first; if we fail this,
1234 * there's no point trying anything else.
1236 * 0x80 is used as a nonsense port to prevent against
1237 * false positives due to ISA bus float. The
1238 * assumption is that 0x80 is a non-existent port;
1239 * which should be safe since include/asm/io.h also
1240 * makes this assumption.
1242 * Note: this is safe as long as MCR bit 4 is clear
1243 * and the device is in "PC" mode.
1245 scratch = serial_in(up, UART_IER);
1246 serial_out(up, UART_IER, 0);
1251 * Mask out IER[7:4] bits for test as some UARTs (e.g. TL
1252 * 16C754B) allow only to modify them if an EFR bit is set.
1254 scratch2 = serial_in(up, UART_IER) & 0x0f;
1255 serial_out(up, UART_IER, 0x0F);
1259 scratch3 = serial_in(up, UART_IER) & 0x0f;
1260 serial_out(up, UART_IER, scratch);
1261 if (scratch2 != 0 || scratch3 != 0x0F) {
1263 * We failed; there's nothing here
1265 spin_unlock_irqrestore(&port->lock, flags);
1266 DEBUG_AUTOCONF("IER test failed (%02x, %02x) ",
1267 scratch2, scratch3);
1272 save_mcr = serial8250_in_MCR(up);
1273 save_lcr = serial_in(up, UART_LCR);
1276 * Check to see if a UART is really there. Certain broken
1277 * internal modems based on the Rockwell chipset fail this
1278 * test, because they apparently don't implement the loopback
1279 * test mode. So this test is skipped on the COM 1 through
1280 * COM 4 ports. This *should* be safe, since no board
1281 * manufacturer would be stupid enough to design a board
1282 * that conflicts with COM 1-4 --- we hope!
1284 if (!(port->flags & UPF_SKIP_TEST)) {
1285 serial8250_out_MCR(up, UART_MCR_LOOP | 0x0A);
1286 status1 = serial_in(up, UART_MSR) & 0xF0;
1287 serial8250_out_MCR(up, save_mcr);
1288 if (status1 != 0x90) {
1289 spin_unlock_irqrestore(&port->lock, flags);
1290 DEBUG_AUTOCONF("LOOP test failed (%02x) ",
1297 * We're pretty sure there's a port here. Lets find out what
1298 * type of port it is. The IIR top two bits allows us to find
1299 * out if it's 8250 or 16450, 16550, 16550A or later. This
1300 * determines what we test for next.
1302 * We also initialise the EFR (if any) to zero for later. The
1303 * EFR occupies the same register location as the FCR and IIR.
1305 serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
1306 serial_out(up, UART_EFR, 0);
1307 serial_out(up, UART_LCR, 0);
1309 serial_out(up, UART_FCR, UART_FCR_ENABLE_FIFO);
1311 /* Assign this as it is to truncate any bits above 7. */
1312 scratch = serial_in(up, UART_IIR);
1314 switch (scratch >> 6) {
1316 autoconfig_8250(up);
1319 port->type = PORT_UNKNOWN;
1322 port->type = PORT_16550;
1325 autoconfig_16550a(up);
1329 #ifdef CONFIG_SERIAL_8250_RSA
1331 * Only probe for RSA ports if we got the region.
1333 if (port->type == PORT_16550A && up->probe & UART_PROBE_RSA &&
1335 port->type = PORT_RSA;
1338 serial_out(up, UART_LCR, save_lcr);
1340 port->fifosize = uart_config[up->port.type].fifo_size;
1341 old_capabilities = up->capabilities;
1342 up->capabilities = uart_config[port->type].flags;
1343 up->tx_loadsz = uart_config[port->type].tx_loadsz;
1345 if (port->type == PORT_UNKNOWN)
1351 #ifdef CONFIG_SERIAL_8250_RSA
1352 if (port->type == PORT_RSA)
1353 serial_out(up, UART_RSA_FRR, 0);
1355 serial8250_out_MCR(up, save_mcr);
1356 serial8250_clear_fifos(up);
1357 serial_in(up, UART_RX);
1358 if (up->capabilities & UART_CAP_UUE)
1359 serial_out(up, UART_IER, UART_IER_UUE);
1361 serial_out(up, UART_IER, 0);
1364 spin_unlock_irqrestore(&port->lock, flags);
1367 * Check if the device is a Fintek F81216A
1369 if (port->type == PORT_16550A && port->iotype == UPIO_PORT)
1370 fintek_8250_probe(up);
1372 if (up->capabilities != old_capabilities) {
1373 pr_warn("ttyS%d: detected caps %08x should be %08x\n",
1374 serial_index(port), old_capabilities,
1378 DEBUG_AUTOCONF("iir=%d ", scratch);
1379 DEBUG_AUTOCONF("type=%s\n", uart_config[port->type].name);
1382 static void autoconfig_irq(struct uart_8250_port *up)
1384 struct uart_port *port = &up->port;
1385 unsigned char save_mcr, save_ier;
1386 unsigned char save_ICP = 0;
1387 unsigned int ICP = 0;
1391 if (port->flags & UPF_FOURPORT) {
1392 ICP = (port->iobase & 0xfe0) | 0x1f;
1393 save_ICP = inb_p(ICP);
1398 if (uart_console(port))
1401 /* forget possible initially masked and pending IRQ */
1402 probe_irq_off(probe_irq_on());
1403 save_mcr = serial8250_in_MCR(up);
1404 save_ier = serial_in(up, UART_IER);
1405 serial8250_out_MCR(up, UART_MCR_OUT1 | UART_MCR_OUT2);
1407 irqs = probe_irq_on();
1408 serial8250_out_MCR(up, 0);
1410 if (port->flags & UPF_FOURPORT) {
1411 serial8250_out_MCR(up, UART_MCR_DTR | UART_MCR_RTS);
1413 serial8250_out_MCR(up,
1414 UART_MCR_DTR | UART_MCR_RTS | UART_MCR_OUT2);
1416 serial_out(up, UART_IER, 0x0f); /* enable all intrs */
1417 serial_in(up, UART_LSR);
1418 serial_in(up, UART_RX);
1419 serial_in(up, UART_IIR);
1420 serial_in(up, UART_MSR);
1421 serial_out(up, UART_TX, 0xFF);
1423 irq = probe_irq_off(irqs);
1425 serial8250_out_MCR(up, save_mcr);
1426 serial_out(up, UART_IER, save_ier);
1428 if (port->flags & UPF_FOURPORT)
1429 outb_p(save_ICP, ICP);
1431 if (uart_console(port))
1434 port->irq = (irq > 0) ? irq : 0;
1437 static void serial8250_stop_rx(struct uart_port *port)
1439 struct uart_8250_port *up = up_to_u8250p(port);
1441 serial8250_rpm_get(up);
1443 up->ier &= ~(UART_IER_RLSI | UART_IER_RDI);
1444 up->port.read_status_mask &= ~UART_LSR_DR;
1445 serial_port_out(port, UART_IER, up->ier);
1447 serial8250_rpm_put(up);
1450 static void __do_stop_tx_rs485(struct uart_8250_port *p)
1452 serial8250_em485_rts_after_send(p);
1455 * Empty the RX FIFO, we are not interested in anything
1456 * received during the half-duplex transmission.
1457 * Enable previously disabled RX interrupts.
1459 if (!(p->port.rs485.flags & SER_RS485_RX_DURING_TX)) {
1460 serial8250_clear_and_reinit_fifos(p);
1462 p->ier |= UART_IER_RLSI | UART_IER_RDI;
1463 serial_port_out(&p->port, UART_IER, p->ier);
1466 static enum hrtimer_restart serial8250_em485_handle_stop_tx(struct hrtimer *t)
1468 struct uart_8250_em485 *em485;
1469 struct uart_8250_port *p;
1470 unsigned long flags;
1472 em485 = container_of(t, struct uart_8250_em485, stop_tx_timer);
1475 serial8250_rpm_get(p);
1476 spin_lock_irqsave(&p->port.lock, flags);
1477 if (em485->active_timer == &em485->stop_tx_timer) {
1478 __do_stop_tx_rs485(p);
1479 em485->active_timer = NULL;
1481 spin_unlock_irqrestore(&p->port.lock, flags);
1482 serial8250_rpm_put(p);
1483 return HRTIMER_NORESTART;
1486 static void start_hrtimer_ms(struct hrtimer *hrt, unsigned long msec)
1488 long sec = msec / 1000;
1489 long nsec = (msec % 1000) * 1000000;
1490 ktime_t t = ktime_set(sec, nsec);
1492 hrtimer_start(hrt, t, HRTIMER_MODE_REL);
1495 static void __stop_tx_rs485(struct uart_8250_port *p)
1497 struct uart_8250_em485 *em485 = p->em485;
1500 * __do_stop_tx_rs485 is going to set RTS according to config
1501 * AND flush RX FIFO if required.
1503 if (p->port.rs485.delay_rts_after_send > 0) {
1504 em485->active_timer = &em485->stop_tx_timer;
1505 start_hrtimer_ms(&em485->stop_tx_timer,
1506 p->port.rs485.delay_rts_after_send);
1508 __do_stop_tx_rs485(p);
1512 static inline void __do_stop_tx(struct uart_8250_port *p)
1514 if (p->ier & UART_IER_THRI) {
1515 p->ier &= ~UART_IER_THRI;
1516 serial_out(p, UART_IER, p->ier);
1517 serial8250_rpm_put_tx(p);
1521 static inline void __stop_tx(struct uart_8250_port *p)
1523 struct uart_8250_em485 *em485 = p->em485;
1526 unsigned char lsr = serial_in(p, UART_LSR);
1528 * To provide required timeing and allow FIFO transfer,
1529 * __stop_tx_rs485() must be called only when both FIFO and
1530 * shift register are empty. It is for device driver to enable
1531 * interrupt on TEMT.
1533 if ((lsr & BOTH_EMPTY) != BOTH_EMPTY)
1536 em485->active_timer = NULL;
1543 static void serial8250_stop_tx(struct uart_port *port)
1545 struct uart_8250_port *up = up_to_u8250p(port);
1547 serial8250_rpm_get(up);
1551 * We really want to stop the transmitter from sending.
1553 if (port->type == PORT_16C950) {
1554 up->acr |= UART_ACR_TXDIS;
1555 serial_icr_write(up, UART_ACR, up->acr);
1557 serial8250_rpm_put(up);
1560 static inline void __start_tx(struct uart_port *port)
1562 struct uart_8250_port *up = up_to_u8250p(port);
1564 if (up->dma && !up->dma->tx_dma(up))
1567 if (!(up->ier & UART_IER_THRI)) {
1568 up->ier |= UART_IER_THRI;
1569 serial_port_out(port, UART_IER, up->ier);
1571 if (up->bugs & UART_BUG_TXEN) {
1574 lsr = serial_in(up, UART_LSR);
1575 up->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS;
1576 if (lsr & UART_LSR_THRE)
1577 serial8250_tx_chars(up);
1582 * Re-enable the transmitter if we disabled it.
1584 if (port->type == PORT_16C950 && up->acr & UART_ACR_TXDIS) {
1585 up->acr &= ~UART_ACR_TXDIS;
1586 serial_icr_write(up, UART_ACR, up->acr);
1590 static inline void start_tx_rs485(struct uart_port *port)
1592 struct uart_8250_port *up = up_to_u8250p(port);
1593 struct uart_8250_em485 *em485 = up->em485;
1596 if (!(up->port.rs485.flags & SER_RS485_RX_DURING_TX))
1597 serial8250_stop_rx(&up->port);
1599 em485->active_timer = NULL;
1601 mcr = serial8250_in_MCR(up);
1602 if (!!(up->port.rs485.flags & SER_RS485_RTS_ON_SEND) !=
1603 !!(mcr & UART_MCR_RTS)) {
1604 if (up->port.rs485.flags & SER_RS485_RTS_ON_SEND)
1605 mcr |= UART_MCR_RTS;
1607 mcr &= ~UART_MCR_RTS;
1608 serial8250_out_MCR(up, mcr);
1610 if (up->port.rs485.delay_rts_before_send > 0) {
1611 em485->active_timer = &em485->start_tx_timer;
1612 start_hrtimer_ms(&em485->start_tx_timer,
1613 up->port.rs485.delay_rts_before_send);
1621 static enum hrtimer_restart serial8250_em485_handle_start_tx(struct hrtimer *t)
1623 struct uart_8250_em485 *em485;
1624 struct uart_8250_port *p;
1625 unsigned long flags;
1627 em485 = container_of(t, struct uart_8250_em485, start_tx_timer);
1630 spin_lock_irqsave(&p->port.lock, flags);
1631 if (em485->active_timer == &em485->start_tx_timer) {
1632 __start_tx(&p->port);
1633 em485->active_timer = NULL;
1635 spin_unlock_irqrestore(&p->port.lock, flags);
1636 return HRTIMER_NORESTART;
1639 static void serial8250_start_tx(struct uart_port *port)
1641 struct uart_8250_port *up = up_to_u8250p(port);
1642 struct uart_8250_em485 *em485 = up->em485;
1644 serial8250_rpm_get_tx(up);
1647 em485->active_timer == &em485->start_tx_timer)
1651 start_tx_rs485(port);
1656 static void serial8250_throttle(struct uart_port *port)
1658 port->throttle(port);
1661 static void serial8250_unthrottle(struct uart_port *port)
1663 port->unthrottle(port);
1666 static void serial8250_disable_ms(struct uart_port *port)
1668 struct uart_8250_port *up = up_to_u8250p(port);
1670 /* no MSR capabilities */
1671 if (up->bugs & UART_BUG_NOMSR)
1674 up->ier &= ~UART_IER_MSI;
1675 serial_port_out(port, UART_IER, up->ier);
1678 static void serial8250_enable_ms(struct uart_port *port)
1680 struct uart_8250_port *up = up_to_u8250p(port);
1682 /* no MSR capabilities */
1683 if (up->bugs & UART_BUG_NOMSR)
1686 up->ier |= UART_IER_MSI;
1688 serial8250_rpm_get(up);
1689 serial_port_out(port, UART_IER, up->ier);
1690 serial8250_rpm_put(up);
1693 static void serial8250_read_char(struct uart_8250_port *up, unsigned char lsr)
1695 struct uart_port *port = &up->port;
1697 char flag = TTY_NORMAL;
1699 if (likely(lsr & UART_LSR_DR))
1700 ch = serial_in(up, UART_RX);
1703 * Intel 82571 has a Serial Over Lan device that will
1704 * set UART_LSR_BI without setting UART_LSR_DR when
1705 * it receives a break. To avoid reading from the
1706 * receive buffer without UART_LSR_DR bit set, we
1707 * just force the read character to be 0
1713 lsr |= up->lsr_saved_flags;
1714 up->lsr_saved_flags = 0;
1716 if (unlikely(lsr & UART_LSR_BRK_ERROR_BITS)) {
1717 if (lsr & UART_LSR_BI) {
1718 lsr &= ~(UART_LSR_FE | UART_LSR_PE);
1721 * We do the SysRQ and SAK checking
1722 * here because otherwise the break
1723 * may get masked by ignore_status_mask
1724 * or read_status_mask.
1726 if (uart_handle_break(port))
1728 } else if (lsr & UART_LSR_PE)
1729 port->icount.parity++;
1730 else if (lsr & UART_LSR_FE)
1731 port->icount.frame++;
1732 if (lsr & UART_LSR_OE)
1733 port->icount.overrun++;
1736 * Mask off conditions which should be ignored.
1738 lsr &= port->read_status_mask;
1740 if (lsr & UART_LSR_BI) {
1741 pr_debug("%s: handling break\n", __func__);
1743 } else if (lsr & UART_LSR_PE)
1745 else if (lsr & UART_LSR_FE)
1748 if (uart_handle_sysrq_char(port, ch))
1751 uart_insert_char(port, lsr, UART_LSR_OE, ch, flag);
1755 * serial8250_rx_chars: processes according to the passed in LSR
1756 * value, and returns the remaining LSR bits not handled
1757 * by this Rx routine.
1759 unsigned char serial8250_rx_chars(struct uart_8250_port *up, unsigned char lsr)
1761 struct uart_port *port = &up->port;
1762 int max_count = 256;
1765 serial8250_read_char(up, lsr);
1766 if (--max_count == 0)
1768 lsr = serial_in(up, UART_LSR);
1769 } while (lsr & (UART_LSR_DR | UART_LSR_BI));
1771 tty_flip_buffer_push(&port->state->port);
1774 EXPORT_SYMBOL_GPL(serial8250_rx_chars);
1776 void serial8250_tx_chars(struct uart_8250_port *up)
1778 struct uart_port *port = &up->port;
1779 struct circ_buf *xmit = &port->state->xmit;
1783 serial_out(up, UART_TX, port->x_char);
1788 if (uart_tx_stopped(port)) {
1789 serial8250_stop_tx(port);
1792 if (uart_circ_empty(xmit)) {
1797 count = up->tx_loadsz;
1799 serial_out(up, UART_TX, xmit->buf[xmit->tail]);
1800 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
1802 if (uart_circ_empty(xmit))
1804 if ((up->capabilities & UART_CAP_HFIFO) &&
1805 (serial_in(up, UART_LSR) & BOTH_EMPTY) != BOTH_EMPTY)
1807 /* The BCM2835 MINI UART THRE bit is really a not-full bit. */
1808 if ((up->capabilities & UART_CAP_MINI) &&
1809 !(serial_in(up, UART_LSR) & UART_LSR_THRE))
1811 } while (--count > 0);
1813 if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
1814 uart_write_wakeup(port);
1817 * With RPM enabled, we have to wait until the FIFO is empty before the
1818 * HW can go idle. So we get here once again with empty FIFO and disable
1819 * the interrupt and RPM in __stop_tx()
1821 if (uart_circ_empty(xmit) && !(up->capabilities & UART_CAP_RPM))
1824 EXPORT_SYMBOL_GPL(serial8250_tx_chars);
1826 /* Caller holds uart port lock */
1827 unsigned int serial8250_modem_status(struct uart_8250_port *up)
1829 struct uart_port *port = &up->port;
1830 unsigned int status = serial_in(up, UART_MSR);
1832 status |= up->msr_saved_flags;
1833 up->msr_saved_flags = 0;
1834 if (status & UART_MSR_ANY_DELTA && up->ier & UART_IER_MSI &&
1835 port->state != NULL) {
1836 if (status & UART_MSR_TERI)
1838 if (status & UART_MSR_DDSR)
1840 if (status & UART_MSR_DDCD)
1841 uart_handle_dcd_change(port, status & UART_MSR_DCD);
1842 if (status & UART_MSR_DCTS)
1843 uart_handle_cts_change(port, status & UART_MSR_CTS);
1845 wake_up_interruptible(&port->state->port.delta_msr_wait);
1850 EXPORT_SYMBOL_GPL(serial8250_modem_status);
1852 static bool handle_rx_dma(struct uart_8250_port *up, unsigned int iir)
1854 switch (iir & 0x3f) {
1855 case UART_IIR_RX_TIMEOUT:
1856 serial8250_rx_dma_flush(up);
1861 return up->dma->rx_dma(up);
1865 * This handles the interrupt from one port.
1867 int serial8250_handle_irq(struct uart_port *port, unsigned int iir)
1869 unsigned char status;
1870 unsigned long flags;
1871 struct uart_8250_port *up = up_to_u8250p(port);
1872 bool skip_rx = false;
1874 if (iir & UART_IIR_NO_INT)
1877 spin_lock_irqsave(&port->lock, flags);
1879 status = serial_port_in(port, UART_LSR);
1882 * If port is stopped and there are no error conditions in the
1883 * FIFO, then don't drain the FIFO, as this may lead to TTY buffer
1884 * overflow. Not servicing, RX FIFO would trigger auto HW flow
1885 * control when FIFO occupancy reaches preset threshold, thus
1886 * halting RX. This only works when auto HW flow control is
1889 if (!(status & (UART_LSR_FIFOE | UART_LSR_BRK_ERROR_BITS)) &&
1890 (port->status & (UPSTAT_AUTOCTS | UPSTAT_AUTORTS)) &&
1891 !(port->read_status_mask & UART_LSR_DR))
1894 if (status & (UART_LSR_DR | UART_LSR_BI) && !skip_rx) {
1895 if (!up->dma || handle_rx_dma(up, iir))
1896 status = serial8250_rx_chars(up, status);
1898 serial8250_modem_status(up);
1899 if ((!up->dma || up->dma->tx_err) && (status & UART_LSR_THRE) &&
1900 (up->ier & UART_IER_THRI))
1901 serial8250_tx_chars(up);
1903 spin_unlock_irqrestore(&port->lock, flags);
1906 EXPORT_SYMBOL_GPL(serial8250_handle_irq);
1908 static int serial8250_default_handle_irq(struct uart_port *port)
1910 struct uart_8250_port *up = up_to_u8250p(port);
1914 serial8250_rpm_get(up);
1916 iir = serial_port_in(port, UART_IIR);
1917 ret = serial8250_handle_irq(port, iir);
1919 serial8250_rpm_put(up);
1924 * Newer 16550 compatible parts such as the SC16C650 & Altera 16550 Soft IP
1925 * have a programmable TX threshold that triggers the THRE interrupt in
1926 * the IIR register. In this case, the THRE interrupt indicates the FIFO
1927 * has space available. Load it up with tx_loadsz bytes.
1929 static int serial8250_tx_threshold_handle_irq(struct uart_port *port)
1931 unsigned long flags;
1932 unsigned int iir = serial_port_in(port, UART_IIR);
1934 /* TX Threshold IRQ triggered so load up FIFO */
1935 if ((iir & UART_IIR_ID) == UART_IIR_THRI) {
1936 struct uart_8250_port *up = up_to_u8250p(port);
1938 spin_lock_irqsave(&port->lock, flags);
1939 serial8250_tx_chars(up);
1940 spin_unlock_irqrestore(&port->lock, flags);
1943 iir = serial_port_in(port, UART_IIR);
1944 return serial8250_handle_irq(port, iir);
1947 static unsigned int serial8250_tx_empty(struct uart_port *port)
1949 struct uart_8250_port *up = up_to_u8250p(port);
1950 unsigned long flags;
1953 serial8250_rpm_get(up);
1955 spin_lock_irqsave(&port->lock, flags);
1956 lsr = serial_port_in(port, UART_LSR);
1957 up->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS;
1958 spin_unlock_irqrestore(&port->lock, flags);
1960 serial8250_rpm_put(up);
1962 return (lsr & BOTH_EMPTY) == BOTH_EMPTY ? TIOCSER_TEMT : 0;
1965 unsigned int serial8250_do_get_mctrl(struct uart_port *port)
1967 struct uart_8250_port *up = up_to_u8250p(port);
1968 unsigned int status;
1971 serial8250_rpm_get(up);
1972 status = serial8250_modem_status(up);
1973 serial8250_rpm_put(up);
1976 if (status & UART_MSR_DCD)
1978 if (status & UART_MSR_RI)
1980 if (status & UART_MSR_DSR)
1982 if (status & UART_MSR_CTS)
1986 EXPORT_SYMBOL_GPL(serial8250_do_get_mctrl);
1988 static unsigned int serial8250_get_mctrl(struct uart_port *port)
1990 if (port->get_mctrl)
1991 return port->get_mctrl(port);
1992 return serial8250_do_get_mctrl(port);
1995 void serial8250_do_set_mctrl(struct uart_port *port, unsigned int mctrl)
1997 struct uart_8250_port *up = up_to_u8250p(port);
1998 unsigned char mcr = 0;
2000 if (mctrl & TIOCM_RTS)
2001 mcr |= UART_MCR_RTS;
2002 if (mctrl & TIOCM_DTR)
2003 mcr |= UART_MCR_DTR;
2004 if (mctrl & TIOCM_OUT1)
2005 mcr |= UART_MCR_OUT1;
2006 if (mctrl & TIOCM_OUT2)
2007 mcr |= UART_MCR_OUT2;
2008 if (mctrl & TIOCM_LOOP)
2009 mcr |= UART_MCR_LOOP;
2011 mcr = (mcr & up->mcr_mask) | up->mcr_force | up->mcr;
2013 serial8250_out_MCR(up, mcr);
2015 EXPORT_SYMBOL_GPL(serial8250_do_set_mctrl);
2017 static void serial8250_set_mctrl(struct uart_port *port, unsigned int mctrl)
2019 if (port->set_mctrl)
2020 port->set_mctrl(port, mctrl);
2022 serial8250_do_set_mctrl(port, mctrl);
2025 static void serial8250_break_ctl(struct uart_port *port, int break_state)
2027 struct uart_8250_port *up = up_to_u8250p(port);
2028 unsigned long flags;
2030 serial8250_rpm_get(up);
2031 spin_lock_irqsave(&port->lock, flags);
2032 if (break_state == -1)
2033 up->lcr |= UART_LCR_SBC;
2035 up->lcr &= ~UART_LCR_SBC;
2036 serial_port_out(port, UART_LCR, up->lcr);
2037 spin_unlock_irqrestore(&port->lock, flags);
2038 serial8250_rpm_put(up);
2042 * Wait for transmitter & holding register to empty
2044 static void wait_for_xmitr(struct uart_8250_port *up, int bits)
2046 unsigned int status, tmout = 10000;
2048 /* Wait up to 10ms for the character(s) to be sent. */
2050 status = serial_in(up, UART_LSR);
2052 up->lsr_saved_flags |= status & LSR_SAVE_FLAGS;
2054 if ((status & bits) == bits)
2059 touch_nmi_watchdog();
2062 /* Wait up to 1s for flow control if necessary */
2063 if (up->port.flags & UPF_CONS_FLOW) {
2064 for (tmout = 1000000; tmout; tmout--) {
2065 unsigned int msr = serial_in(up, UART_MSR);
2066 up->msr_saved_flags |= msr & MSR_SAVE_FLAGS;
2067 if (msr & UART_MSR_CTS)
2070 touch_nmi_watchdog();
2075 #ifdef CONFIG_CONSOLE_POLL
2077 * Console polling routines for writing and reading from the uart while
2078 * in an interrupt or debug context.
2081 static int serial8250_get_poll_char(struct uart_port *port)
2083 struct uart_8250_port *up = up_to_u8250p(port);
2087 serial8250_rpm_get(up);
2089 lsr = serial_port_in(port, UART_LSR);
2091 if (!(lsr & UART_LSR_DR)) {
2092 status = NO_POLL_CHAR;
2096 status = serial_port_in(port, UART_RX);
2098 serial8250_rpm_put(up);
2103 static void serial8250_put_poll_char(struct uart_port *port,
2107 struct uart_8250_port *up = up_to_u8250p(port);
2109 serial8250_rpm_get(up);
2111 * First save the IER then disable the interrupts
2113 ier = serial_port_in(port, UART_IER);
2114 if (up->capabilities & UART_CAP_UUE)
2115 serial_port_out(port, UART_IER, UART_IER_UUE);
2117 serial_port_out(port, UART_IER, 0);
2119 wait_for_xmitr(up, BOTH_EMPTY);
2121 * Send the character out.
2123 serial_port_out(port, UART_TX, c);
2126 * Finally, wait for transmitter to become empty
2127 * and restore the IER
2129 wait_for_xmitr(up, BOTH_EMPTY);
2130 serial_port_out(port, UART_IER, ier);
2131 serial8250_rpm_put(up);
2134 #endif /* CONFIG_CONSOLE_POLL */
2136 int serial8250_do_startup(struct uart_port *port)
2138 struct uart_8250_port *up = up_to_u8250p(port);
2139 unsigned long flags;
2140 unsigned char lsr, iir;
2143 if (!port->fifosize)
2144 port->fifosize = uart_config[port->type].fifo_size;
2146 up->tx_loadsz = uart_config[port->type].tx_loadsz;
2147 if (!up->capabilities)
2148 up->capabilities = uart_config[port->type].flags;
2151 if (port->iotype != up->cur_iotype)
2152 set_io_from_upio(port);
2154 serial8250_rpm_get(up);
2155 if (port->type == PORT_16C950) {
2156 /* Wake up and initialize UART */
2158 serial_port_out(port, UART_LCR, UART_LCR_CONF_MODE_B);
2159 serial_port_out(port, UART_EFR, UART_EFR_ECB);
2160 serial_port_out(port, UART_IER, 0);
2161 serial_port_out(port, UART_LCR, 0);
2162 serial_icr_write(up, UART_CSR, 0); /* Reset the UART */
2163 serial_port_out(port, UART_LCR, UART_LCR_CONF_MODE_B);
2164 serial_port_out(port, UART_EFR, UART_EFR_ECB);
2165 serial_port_out(port, UART_LCR, 0);
2168 if (port->type == PORT_DA830) {
2169 /* Reset the port */
2170 serial_port_out(port, UART_IER, 0);
2171 serial_port_out(port, UART_DA830_PWREMU_MGMT, 0);
2174 /* Enable Tx, Rx and free run mode */
2175 serial_port_out(port, UART_DA830_PWREMU_MGMT,
2176 UART_DA830_PWREMU_MGMT_UTRST |
2177 UART_DA830_PWREMU_MGMT_URRST |
2178 UART_DA830_PWREMU_MGMT_FREE);
2181 if (port->type == PORT_NPCM) {
2183 * Nuvoton calls the scratch register 'UART_TOR' (timeout
2184 * register). Enable it, and set TIOC (timeout interrupt
2185 * comparator) to be 0x20 for correct operation.
2187 serial_port_out(port, UART_NPCM_TOR, UART_NPCM_TOIE | 0x20);
2190 #ifdef CONFIG_SERIAL_8250_RSA
2192 * If this is an RSA port, see if we can kick it up to the
2193 * higher speed clock.
2198 if (port->type == PORT_XR17V35X) {
2200 * First enable access to IER [7:5], ISR [5:4], FCR [5:4],
2201 * MCR [7:5] and MSR [7:0]
2203 serial_port_out(port, UART_XR_EFR, UART_EFR_ECB);
2206 * Make sure all interrups are masked until initialization is
2207 * complete and the FIFOs are cleared
2209 serial_port_out(port, UART_IER, 0);
2213 * Clear the FIFO buffers and disable them.
2214 * (they will be reenabled in set_termios())
2216 serial8250_clear_fifos(up);
2219 * Clear the interrupt registers.
2221 serial_port_in(port, UART_LSR);
2222 serial_port_in(port, UART_RX);
2223 serial_port_in(port, UART_IIR);
2224 serial_port_in(port, UART_MSR);
2225 if ((port->type == PORT_XR17V35X) || (port->type == PORT_XR17D15X))
2226 serial_port_in(port, UART_EXAR_INT0);
2229 * At this point, there's no way the LSR could still be 0xff;
2230 * if it is, then bail out, because there's likely no UART
2233 if (!(port->flags & UPF_BUGGY_UART) &&
2234 (serial_port_in(port, UART_LSR) == 0xff)) {
2235 printk_ratelimited(KERN_INFO "ttyS%d: LSR safety check engaged!\n",
2236 serial_index(port));
2242 * For a XR16C850, we need to set the trigger levels
2244 if (port->type == PORT_16850) {
2247 serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
2249 fctr = serial_in(up, UART_FCTR) & ~(UART_FCTR_RX|UART_FCTR_TX);
2250 serial_port_out(port, UART_FCTR,
2251 fctr | UART_FCTR_TRGD | UART_FCTR_RX);
2252 serial_port_out(port, UART_TRG, UART_TRG_96);
2253 serial_port_out(port, UART_FCTR,
2254 fctr | UART_FCTR_TRGD | UART_FCTR_TX);
2255 serial_port_out(port, UART_TRG, UART_TRG_96);
2257 serial_port_out(port, UART_LCR, 0);
2261 * For the Altera 16550 variants, set TX threshold trigger level.
2263 if (((port->type == PORT_ALTR_16550_F32) ||
2264 (port->type == PORT_ALTR_16550_F64) ||
2265 (port->type == PORT_ALTR_16550_F128)) && (port->fifosize > 1)) {
2266 /* Bounds checking of TX threshold (valid 0 to fifosize-2) */
2267 if ((up->tx_loadsz < 2) || (up->tx_loadsz > port->fifosize)) {
2268 pr_err("ttyS%d TX FIFO Threshold errors, skipping\n",
2269 serial_index(port));
2271 serial_port_out(port, UART_ALTR_AFR,
2272 UART_ALTR_EN_TXFIFO_LW);
2273 serial_port_out(port, UART_ALTR_TX_LOW,
2274 port->fifosize - up->tx_loadsz);
2275 port->handle_irq = serial8250_tx_threshold_handle_irq;
2279 /* Check if we need to have shared IRQs */
2280 if (port->irq && (up->port.flags & UPF_SHARE_IRQ))
2281 up->port.irqflags |= IRQF_SHARED;
2283 if (port->irq && !(up->port.flags & UPF_NO_THRE_TEST)) {
2286 if (port->irqflags & IRQF_SHARED)
2287 disable_irq_nosync(port->irq);
2290 * Test for UARTs that do not reassert THRE when the
2291 * transmitter is idle and the interrupt has already
2292 * been cleared. Real 16550s should always reassert
2293 * this interrupt whenever the transmitter is idle and
2294 * the interrupt is enabled. Delays are necessary to
2295 * allow register changes to become visible.
2297 spin_lock_irqsave(&port->lock, flags);
2299 wait_for_xmitr(up, UART_LSR_THRE);
2300 serial_port_out_sync(port, UART_IER, UART_IER_THRI);
2301 udelay(1); /* allow THRE to set */
2302 iir1 = serial_port_in(port, UART_IIR);
2303 serial_port_out(port, UART_IER, 0);
2304 serial_port_out_sync(port, UART_IER, UART_IER_THRI);
2305 udelay(1); /* allow a working UART time to re-assert THRE */
2306 iir = serial_port_in(port, UART_IIR);
2307 serial_port_out(port, UART_IER, 0);
2309 spin_unlock_irqrestore(&port->lock, flags);
2311 if (port->irqflags & IRQF_SHARED)
2312 enable_irq(port->irq);
2315 * If the interrupt is not reasserted, or we otherwise
2316 * don't trust the iir, setup a timer to kick the UART
2317 * on a regular basis.
2319 if ((!(iir1 & UART_IIR_NO_INT) && (iir & UART_IIR_NO_INT)) ||
2320 up->port.flags & UPF_BUG_THRE) {
2321 up->bugs |= UART_BUG_THRE;
2325 retval = up->ops->setup_irq(up);
2330 * Now, initialize the UART
2332 serial_port_out(port, UART_LCR, UART_LCR_WLEN8);
2334 spin_lock_irqsave(&port->lock, flags);
2335 if (up->port.flags & UPF_FOURPORT) {
2337 up->port.mctrl |= TIOCM_OUT1;
2340 * Most PC uarts need OUT2 raised to enable interrupts.
2343 up->port.mctrl |= TIOCM_OUT2;
2345 serial8250_set_mctrl(port, port->mctrl);
2348 * Serial over Lan (SoL) hack:
2349 * Intel 8257x Gigabit ethernet chips have a 16550 emulation, to be
2350 * used for Serial Over Lan. Those chips take a longer time than a
2351 * normal serial device to signalize that a transmission data was
2352 * queued. Due to that, the above test generally fails. One solution
2353 * would be to delay the reading of iir. However, this is not
2354 * reliable, since the timeout is variable. So, let's just don't
2355 * test if we receive TX irq. This way, we'll never enable
2358 if (up->port.quirks & UPQ_NO_TXEN_TEST)
2359 goto dont_test_tx_en;
2362 * Do a quick test to see if we receive an interrupt when we enable
2365 serial_port_out(port, UART_IER, UART_IER_THRI);
2366 lsr = serial_port_in(port, UART_LSR);
2367 iir = serial_port_in(port, UART_IIR);
2368 serial_port_out(port, UART_IER, 0);
2370 if (lsr & UART_LSR_TEMT && iir & UART_IIR_NO_INT) {
2371 if (!(up->bugs & UART_BUG_TXEN)) {
2372 up->bugs |= UART_BUG_TXEN;
2373 pr_debug("ttyS%d - enabling bad tx status workarounds\n",
2374 serial_index(port));
2377 up->bugs &= ~UART_BUG_TXEN;
2381 spin_unlock_irqrestore(&port->lock, flags);
2384 * Clear the interrupt registers again for luck, and clear the
2385 * saved flags to avoid getting false values from polling
2386 * routines or the previous session.
2388 serial_port_in(port, UART_LSR);
2389 serial_port_in(port, UART_RX);
2390 serial_port_in(port, UART_IIR);
2391 serial_port_in(port, UART_MSR);
2392 if ((port->type == PORT_XR17V35X) || (port->type == PORT_XR17D15X))
2393 serial_port_in(port, UART_EXAR_INT0);
2394 up->lsr_saved_flags = 0;
2395 up->msr_saved_flags = 0;
2398 * Request DMA channels for both RX and TX.
2401 retval = serial8250_request_dma(up);
2403 pr_warn_ratelimited("ttyS%d - failed to request DMA\n",
2404 serial_index(port));
2410 * Set the IER shadow for rx interrupts but defer actual interrupt
2411 * enable until after the FIFOs are enabled; otherwise, an already-
2412 * active sender can swamp the interrupt handler with "too much work".
2414 up->ier = UART_IER_RLSI | UART_IER_RDI;
2416 if (port->flags & UPF_FOURPORT) {
2419 * Enable interrupts on the AST Fourport board
2421 icp = (port->iobase & 0xfe0) | 0x01f;
2427 serial8250_rpm_put(up);
2430 EXPORT_SYMBOL_GPL(serial8250_do_startup);
2432 static int serial8250_startup(struct uart_port *port)
2435 return port->startup(port);
2436 return serial8250_do_startup(port);
2439 void serial8250_do_shutdown(struct uart_port *port)
2441 struct uart_8250_port *up = up_to_u8250p(port);
2442 unsigned long flags;
2444 serial8250_rpm_get(up);
2446 * Disable interrupts from this port
2448 spin_lock_irqsave(&port->lock, flags);
2450 serial_port_out(port, UART_IER, 0);
2451 spin_unlock_irqrestore(&port->lock, flags);
2453 synchronize_irq(port->irq);
2456 serial8250_release_dma(up);
2458 spin_lock_irqsave(&port->lock, flags);
2459 if (port->flags & UPF_FOURPORT) {
2460 /* reset interrupts on the AST Fourport board */
2461 inb((port->iobase & 0xfe0) | 0x1f);
2462 port->mctrl |= TIOCM_OUT1;
2464 port->mctrl &= ~TIOCM_OUT2;
2466 serial8250_set_mctrl(port, port->mctrl);
2467 spin_unlock_irqrestore(&port->lock, flags);
2470 * Disable break condition and FIFOs
2472 serial_port_out(port, UART_LCR,
2473 serial_port_in(port, UART_LCR) & ~UART_LCR_SBC);
2474 serial8250_clear_fifos(up);
2476 #ifdef CONFIG_SERIAL_8250_RSA
2478 * Reset the RSA board back to 115kbps compat mode.
2484 * Read data port to reset things, and then unlink from
2487 serial_port_in(port, UART_RX);
2488 serial8250_rpm_put(up);
2490 up->ops->release_irq(up);
2492 EXPORT_SYMBOL_GPL(serial8250_do_shutdown);
2494 static void serial8250_shutdown(struct uart_port *port)
2497 port->shutdown(port);
2499 serial8250_do_shutdown(port);
2503 * XR17V35x UARTs have an extra fractional divisor register (DLD)
2504 * Calculate divisor with extra 4-bit fractional portion
2506 static unsigned int xr17v35x_get_divisor(struct uart_8250_port *up,
2510 struct uart_port *port = &up->port;
2511 unsigned int quot_16;
2513 quot_16 = DIV_ROUND_CLOSEST(port->uartclk, baud);
2514 *frac = quot_16 & 0x0f;
2516 return quot_16 >> 4;
2519 /* Nuvoton NPCM UARTs have a custom divisor calculation */
2520 static unsigned int npcm_get_divisor(struct uart_8250_port *up,
2523 struct uart_port *port = &up->port;
2525 return DIV_ROUND_CLOSEST(port->uartclk, 16 * baud + 2) - 2;
2528 static unsigned int serial8250_get_divisor(struct uart_8250_port *up,
2532 struct uart_port *port = &up->port;
2536 * Handle magic divisors for baud rates above baud_base on
2537 * SMSC SuperIO chips.
2540 if ((port->flags & UPF_MAGIC_MULTIPLIER) &&
2541 baud == (port->uartclk/4))
2543 else if ((port->flags & UPF_MAGIC_MULTIPLIER) &&
2544 baud == (port->uartclk/8))
2546 else if (up->port.type == PORT_XR17V35X)
2547 quot = xr17v35x_get_divisor(up, baud, frac);
2548 else if (up->port.type == PORT_NPCM)
2549 quot = npcm_get_divisor(up, baud);
2551 quot = uart_get_divisor(port, baud);
2554 * Oxford Semi 952 rev B workaround
2556 if (up->bugs & UART_BUG_QUOT && (quot & 0xff) == 0)
2562 static unsigned char serial8250_compute_lcr(struct uart_8250_port *up,
2567 switch (c_cflag & CSIZE) {
2569 cval = UART_LCR_WLEN5;
2572 cval = UART_LCR_WLEN6;
2575 cval = UART_LCR_WLEN7;
2579 cval = UART_LCR_WLEN8;
2583 if (c_cflag & CSTOPB)
2584 cval |= UART_LCR_STOP;
2585 if (c_cflag & PARENB) {
2586 cval |= UART_LCR_PARITY;
2587 if (up->bugs & UART_BUG_PARITY)
2588 up->fifo_bug = true;
2590 if (!(c_cflag & PARODD))
2591 cval |= UART_LCR_EPAR;
2593 if (c_cflag & CMSPAR)
2594 cval |= UART_LCR_SPAR;
2600 static void serial8250_set_divisor(struct uart_port *port, unsigned int baud,
2601 unsigned int quot, unsigned int quot_frac)
2603 struct uart_8250_port *up = up_to_u8250p(port);
2605 /* Workaround to enable 115200 baud on OMAP1510 internal ports */
2606 if (is_omap1510_8250(up)) {
2607 if (baud == 115200) {
2609 serial_port_out(port, UART_OMAP_OSC_12M_SEL, 1);
2611 serial_port_out(port, UART_OMAP_OSC_12M_SEL, 0);
2615 * For NatSemi, switch to bank 2 not bank 1, to avoid resetting EXCR2,
2616 * otherwise just set DLAB
2618 if (up->capabilities & UART_NATSEMI)
2619 serial_port_out(port, UART_LCR, 0xe0);
2621 serial_port_out(port, UART_LCR, up->lcr | UART_LCR_DLAB);
2623 serial_dl_write(up, quot);
2625 /* XR17V35x UARTs have an extra fractional divisor register (DLD) */
2626 if (up->port.type == PORT_XR17V35X) {
2627 /* Preserve bits not related to baudrate; DLD[7:4]. */
2628 quot_frac |= serial_port_in(port, 0x2) & 0xf0;
2629 serial_port_out(port, 0x2, quot_frac);
2633 static unsigned int serial8250_get_baud_rate(struct uart_port *port,
2634 struct ktermios *termios,
2635 struct ktermios *old)
2638 * Ask the core to calculate the divisor for us.
2639 * Allow 1% tolerance at the upper limit so uart clks marginally
2640 * slower than nominal still match standard baud rates without
2641 * causing transmission errors.
2643 return uart_get_baud_rate(port, termios, old,
2644 port->uartclk / 16 / 0xffff,
2649 serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
2650 struct ktermios *old)
2652 struct uart_8250_port *up = up_to_u8250p(port);
2654 unsigned long flags;
2655 unsigned int baud, quot, frac = 0;
2657 if (up->capabilities & UART_CAP_MINI) {
2658 termios->c_cflag &= ~(CSTOPB | PARENB | PARODD | CMSPAR);
2659 if ((termios->c_cflag & CSIZE) == CS5 ||
2660 (termios->c_cflag & CSIZE) == CS6)
2661 termios->c_cflag = (termios->c_cflag & ~CSIZE) | CS7;
2663 cval = serial8250_compute_lcr(up, termios->c_cflag);
2665 baud = serial8250_get_baud_rate(port, termios, old);
2666 quot = serial8250_get_divisor(up, baud, &frac);
2669 * Ok, we're now changing the port state. Do it with
2670 * interrupts disabled.
2672 serial8250_rpm_get(up);
2673 spin_lock_irqsave(&port->lock, flags);
2675 up->lcr = cval; /* Save computed LCR */
2677 if (up->capabilities & UART_CAP_FIFO && port->fifosize > 1) {
2678 /* NOTE: If fifo_bug is not set, a user can set RX_trigger. */
2679 if ((baud < 2400 && !up->dma) || up->fifo_bug) {
2680 up->fcr &= ~UART_FCR_TRIGGER_MASK;
2681 up->fcr |= UART_FCR_TRIGGER_1;
2686 * MCR-based auto flow control. When AFE is enabled, RTS will be
2687 * deasserted when the receive FIFO contains more characters than
2688 * the trigger, or the MCR RTS bit is cleared.
2690 if (up->capabilities & UART_CAP_AFE) {
2691 up->mcr &= ~UART_MCR_AFE;
2692 if (termios->c_cflag & CRTSCTS)
2693 up->mcr |= UART_MCR_AFE;
2697 * Update the per-port timeout.
2699 uart_update_timeout(port, termios->c_cflag, baud);
2701 port->read_status_mask = UART_LSR_OE | UART_LSR_THRE | UART_LSR_DR;
2702 if (termios->c_iflag & INPCK)
2703 port->read_status_mask |= UART_LSR_FE | UART_LSR_PE;
2704 if (termios->c_iflag & (IGNBRK | BRKINT | PARMRK))
2705 port->read_status_mask |= UART_LSR_BI;
2708 * Characteres to ignore
2710 port->ignore_status_mask = 0;
2711 if (termios->c_iflag & IGNPAR)
2712 port->ignore_status_mask |= UART_LSR_PE | UART_LSR_FE;
2713 if (termios->c_iflag & IGNBRK) {
2714 port->ignore_status_mask |= UART_LSR_BI;
2716 * If we're ignoring parity and break indicators,
2717 * ignore overruns too (for real raw support).
2719 if (termios->c_iflag & IGNPAR)
2720 port->ignore_status_mask |= UART_LSR_OE;
2724 * ignore all characters if CREAD is not set
2726 if ((termios->c_cflag & CREAD) == 0)
2727 port->ignore_status_mask |= UART_LSR_DR;
2730 * CTS flow control flag and modem status interrupts
2732 up->ier &= ~UART_IER_MSI;
2733 if (!(up->bugs & UART_BUG_NOMSR) &&
2734 UART_ENABLE_MS(&up->port, termios->c_cflag))
2735 up->ier |= UART_IER_MSI;
2736 if (up->capabilities & UART_CAP_UUE)
2737 up->ier |= UART_IER_UUE;
2738 if (up->capabilities & UART_CAP_RTOIE)
2739 up->ier |= UART_IER_RTOIE;
2741 serial_port_out(port, UART_IER, up->ier);
2743 if (up->capabilities & UART_CAP_EFR) {
2744 unsigned char efr = 0;
2746 * TI16C752/Startech hardware flow control. FIXME:
2747 * - TI16C752 requires control thresholds to be set.
2748 * - UART_MCR_RTS is ineffective if auto-RTS mode is enabled.
2750 if (termios->c_cflag & CRTSCTS)
2751 efr |= UART_EFR_CTS;
2753 serial_port_out(port, UART_LCR, UART_LCR_CONF_MODE_B);
2754 if (port->flags & UPF_EXAR_EFR)
2755 serial_port_out(port, UART_XR_EFR, efr);
2757 serial_port_out(port, UART_EFR, efr);
2760 serial8250_set_divisor(port, baud, quot, frac);
2763 * LCR DLAB must be set to enable 64-byte FIFO mode. If the FCR
2764 * is written without DLAB set, this mode will be disabled.
2766 if (port->type == PORT_16750)
2767 serial_port_out(port, UART_FCR, up->fcr);
2769 serial_port_out(port, UART_LCR, up->lcr); /* reset DLAB */
2770 if (port->type != PORT_16750) {
2771 /* emulated UARTs (Lucent Venus 167x) need two steps */
2772 if (up->fcr & UART_FCR_ENABLE_FIFO)
2773 serial_port_out(port, UART_FCR, UART_FCR_ENABLE_FIFO);
2774 serial_port_out(port, UART_FCR, up->fcr); /* set fcr */
2776 serial8250_set_mctrl(port, port->mctrl);
2777 spin_unlock_irqrestore(&port->lock, flags);
2778 serial8250_rpm_put(up);
2780 /* Don't rewrite B0 */
2781 if (tty_termios_baud_rate(termios))
2782 tty_termios_encode_baud_rate(termios, baud, baud);
2784 EXPORT_SYMBOL(serial8250_do_set_termios);
2787 serial8250_set_termios(struct uart_port *port, struct ktermios *termios,
2788 struct ktermios *old)
2790 if (port->set_termios)
2791 port->set_termios(port, termios, old);
2793 serial8250_do_set_termios(port, termios, old);
2796 void serial8250_do_set_ldisc(struct uart_port *port, struct ktermios *termios)
2798 if (termios->c_line == N_PPS) {
2799 port->flags |= UPF_HARDPPS_CD;
2800 spin_lock_irq(&port->lock);
2801 serial8250_enable_ms(port);
2802 spin_unlock_irq(&port->lock);
2804 port->flags &= ~UPF_HARDPPS_CD;
2805 if (!UART_ENABLE_MS(port, termios->c_cflag)) {
2806 spin_lock_irq(&port->lock);
2807 serial8250_disable_ms(port);
2808 spin_unlock_irq(&port->lock);
2812 EXPORT_SYMBOL_GPL(serial8250_do_set_ldisc);
2815 serial8250_set_ldisc(struct uart_port *port, struct ktermios *termios)
2817 if (port->set_ldisc)
2818 port->set_ldisc(port, termios);
2820 serial8250_do_set_ldisc(port, termios);
2823 void serial8250_do_pm(struct uart_port *port, unsigned int state,
2824 unsigned int oldstate)
2826 struct uart_8250_port *p = up_to_u8250p(port);
2828 serial8250_set_sleep(p, state != 0);
2830 EXPORT_SYMBOL(serial8250_do_pm);
2833 serial8250_pm(struct uart_port *port, unsigned int state,
2834 unsigned int oldstate)
2837 port->pm(port, state, oldstate);
2839 serial8250_do_pm(port, state, oldstate);
2842 static unsigned int serial8250_port_size(struct uart_8250_port *pt)
2844 if (pt->port.mapsize)
2845 return pt->port.mapsize;
2846 if (pt->port.iotype == UPIO_AU) {
2847 if (pt->port.type == PORT_RT2880)
2851 if (is_omap1_8250(pt))
2852 return 0x16 << pt->port.regshift;
2854 return 8 << pt->port.regshift;
2858 * Resource handling.
2860 static int serial8250_request_std_resource(struct uart_8250_port *up)
2862 unsigned int size = serial8250_port_size(up);
2863 struct uart_port *port = &up->port;
2866 switch (port->iotype) {
2876 if (!request_mem_region(port->mapbase, size, "serial")) {
2881 if (port->flags & UPF_IOREMAP) {
2882 port->membase = ioremap_nocache(port->mapbase, size);
2883 if (!port->membase) {
2884 release_mem_region(port->mapbase, size);
2892 if (!request_region(port->iobase, size, "serial"))
2899 static void serial8250_release_std_resource(struct uart_8250_port *up)
2901 unsigned int size = serial8250_port_size(up);
2902 struct uart_port *port = &up->port;
2904 switch (port->iotype) {
2914 if (port->flags & UPF_IOREMAP) {
2915 iounmap(port->membase);
2916 port->membase = NULL;
2919 release_mem_region(port->mapbase, size);
2924 release_region(port->iobase, size);
2929 static void serial8250_release_port(struct uart_port *port)
2931 struct uart_8250_port *up = up_to_u8250p(port);
2933 serial8250_release_std_resource(up);
2936 static int serial8250_request_port(struct uart_port *port)
2938 struct uart_8250_port *up = up_to_u8250p(port);
2940 return serial8250_request_std_resource(up);
2943 static int fcr_get_rxtrig_bytes(struct uart_8250_port *up)
2945 const struct serial8250_config *conf_type = &uart_config[up->port.type];
2946 unsigned char bytes;
2948 bytes = conf_type->rxtrig_bytes[UART_FCR_R_TRIG_BITS(up->fcr)];
2950 return bytes ? bytes : -EOPNOTSUPP;
2953 static int bytes_to_fcr_rxtrig(struct uart_8250_port *up, unsigned char bytes)
2955 const struct serial8250_config *conf_type = &uart_config[up->port.type];
2958 if (!conf_type->rxtrig_bytes[UART_FCR_R_TRIG_BITS(UART_FCR_R_TRIG_00)])
2961 for (i = 1; i < UART_FCR_R_TRIG_MAX_STATE; i++) {
2962 if (bytes < conf_type->rxtrig_bytes[i])
2963 /* Use the nearest lower value */
2964 return (--i) << UART_FCR_R_TRIG_SHIFT;
2967 return UART_FCR_R_TRIG_11;
2970 static int do_get_rxtrig(struct tty_port *port)
2972 struct uart_state *state = container_of(port, struct uart_state, port);
2973 struct uart_port *uport = state->uart_port;
2974 struct uart_8250_port *up = up_to_u8250p(uport);
2976 if (!(up->capabilities & UART_CAP_FIFO) || uport->fifosize <= 1)
2979 return fcr_get_rxtrig_bytes(up);
2982 static int do_serial8250_get_rxtrig(struct tty_port *port)
2986 mutex_lock(&port->mutex);
2987 rxtrig_bytes = do_get_rxtrig(port);
2988 mutex_unlock(&port->mutex);
2990 return rxtrig_bytes;
2993 static ssize_t serial8250_get_attr_rx_trig_bytes(struct device *dev,
2994 struct device_attribute *attr, char *buf)
2996 struct tty_port *port = dev_get_drvdata(dev);
2999 rxtrig_bytes = do_serial8250_get_rxtrig(port);
3000 if (rxtrig_bytes < 0)
3001 return rxtrig_bytes;
3003 return snprintf(buf, PAGE_SIZE, "%d\n", rxtrig_bytes);
3006 static int do_set_rxtrig(struct tty_port *port, unsigned char bytes)
3008 struct uart_state *state = container_of(port, struct uart_state, port);
3009 struct uart_port *uport = state->uart_port;
3010 struct uart_8250_port *up = up_to_u8250p(uport);
3013 if (!(up->capabilities & UART_CAP_FIFO) || uport->fifosize <= 1 ||
3017 rxtrig = bytes_to_fcr_rxtrig(up, bytes);
3021 serial8250_clear_fifos(up);
3022 up->fcr &= ~UART_FCR_TRIGGER_MASK;
3023 up->fcr |= (unsigned char)rxtrig;
3024 serial_out(up, UART_FCR, up->fcr);
3028 static int do_serial8250_set_rxtrig(struct tty_port *port, unsigned char bytes)
3032 mutex_lock(&port->mutex);
3033 ret = do_set_rxtrig(port, bytes);
3034 mutex_unlock(&port->mutex);
3039 static ssize_t serial8250_set_attr_rx_trig_bytes(struct device *dev,
3040 struct device_attribute *attr, const char *buf, size_t count)
3042 struct tty_port *port = dev_get_drvdata(dev);
3043 unsigned char bytes;
3049 ret = kstrtou8(buf, 10, &bytes);
3053 ret = do_serial8250_set_rxtrig(port, bytes);
3060 static DEVICE_ATTR(rx_trig_bytes, S_IRUSR | S_IWUSR | S_IRGRP,
3061 serial8250_get_attr_rx_trig_bytes,
3062 serial8250_set_attr_rx_trig_bytes);
3064 static struct attribute *serial8250_dev_attrs[] = {
3065 &dev_attr_rx_trig_bytes.attr,
3069 static struct attribute_group serial8250_dev_attr_group = {
3070 .attrs = serial8250_dev_attrs,
3073 static void register_dev_spec_attr_grp(struct uart_8250_port *up)
3075 const struct serial8250_config *conf_type = &uart_config[up->port.type];
3077 if (conf_type->rxtrig_bytes[0])
3078 up->port.attr_group = &serial8250_dev_attr_group;
3081 static void serial8250_config_port(struct uart_port *port, int flags)
3083 struct uart_8250_port *up = up_to_u8250p(port);
3087 * Find the region that we can probe for. This in turn
3088 * tells us whether we can probe for the type of port.
3090 ret = serial8250_request_std_resource(up);
3094 if (port->iotype != up->cur_iotype)
3095 set_io_from_upio(port);
3097 if (flags & UART_CONFIG_TYPE)
3100 /* if access method is AU, it is a 16550 with a quirk */
3101 if (port->type == PORT_16550A && port->iotype == UPIO_AU)
3102 up->bugs |= UART_BUG_NOMSR;
3104 /* HW bugs may trigger IRQ while IIR == NO_INT */
3105 if (port->type == PORT_TEGRA)
3106 up->bugs |= UART_BUG_NOMSR;
3108 if (port->type != PORT_UNKNOWN && flags & UART_CONFIG_IRQ)
3111 if (port->type == PORT_UNKNOWN)
3112 serial8250_release_std_resource(up);
3114 register_dev_spec_attr_grp(up);
3115 up->fcr = uart_config[up->port.type].fcr;
3119 serial8250_verify_port(struct uart_port *port, struct serial_struct *ser)
3121 if (ser->irq >= nr_irqs || ser->irq < 0 ||
3122 ser->baud_base < 9600 || ser->type < PORT_UNKNOWN ||
3123 ser->type >= ARRAY_SIZE(uart_config) || ser->type == PORT_CIRRUS ||
3124 ser->type == PORT_STARTECH)
3129 static const char *serial8250_type(struct uart_port *port)
3131 int type = port->type;
3133 if (type >= ARRAY_SIZE(uart_config))
3135 return uart_config[type].name;
3138 static const struct uart_ops serial8250_pops = {
3139 .tx_empty = serial8250_tx_empty,
3140 .set_mctrl = serial8250_set_mctrl,
3141 .get_mctrl = serial8250_get_mctrl,
3142 .stop_tx = serial8250_stop_tx,
3143 .start_tx = serial8250_start_tx,
3144 .throttle = serial8250_throttle,
3145 .unthrottle = serial8250_unthrottle,
3146 .stop_rx = serial8250_stop_rx,
3147 .enable_ms = serial8250_enable_ms,
3148 .break_ctl = serial8250_break_ctl,
3149 .startup = serial8250_startup,
3150 .shutdown = serial8250_shutdown,
3151 .set_termios = serial8250_set_termios,
3152 .set_ldisc = serial8250_set_ldisc,
3153 .pm = serial8250_pm,
3154 .type = serial8250_type,
3155 .release_port = serial8250_release_port,
3156 .request_port = serial8250_request_port,
3157 .config_port = serial8250_config_port,
3158 .verify_port = serial8250_verify_port,
3159 #ifdef CONFIG_CONSOLE_POLL
3160 .poll_get_char = serial8250_get_poll_char,
3161 .poll_put_char = serial8250_put_poll_char,
3165 void serial8250_init_port(struct uart_8250_port *up)
3167 struct uart_port *port = &up->port;
3169 spin_lock_init(&port->lock);
3170 port->ops = &serial8250_pops;
3172 up->cur_iotype = 0xFF;
3174 EXPORT_SYMBOL_GPL(serial8250_init_port);
3176 void serial8250_set_defaults(struct uart_8250_port *up)
3178 struct uart_port *port = &up->port;
3180 if (up->port.flags & UPF_FIXED_TYPE) {
3181 unsigned int type = up->port.type;
3183 if (!up->port.fifosize)
3184 up->port.fifosize = uart_config[type].fifo_size;
3186 up->tx_loadsz = uart_config[type].tx_loadsz;
3187 if (!up->capabilities)
3188 up->capabilities = uart_config[type].flags;
3191 set_io_from_upio(port);
3193 /* default dma handlers */
3195 if (!up->dma->tx_dma)
3196 up->dma->tx_dma = serial8250_tx_dma;
3197 if (!up->dma->rx_dma)
3198 up->dma->rx_dma = serial8250_rx_dma;
3201 EXPORT_SYMBOL_GPL(serial8250_set_defaults);
3203 #ifdef CONFIG_SERIAL_8250_CONSOLE
3205 static void serial8250_console_putchar(struct uart_port *port, int ch)
3207 struct uart_8250_port *up = up_to_u8250p(port);
3209 wait_for_xmitr(up, UART_LSR_THRE);
3210 serial_port_out(port, UART_TX, ch);
3214 * Restore serial console when h/w power-off detected
3216 static void serial8250_console_restore(struct uart_8250_port *up)
3218 struct uart_port *port = &up->port;
3219 struct ktermios termios;
3220 unsigned int baud, quot, frac = 0;
3222 termios.c_cflag = port->cons->cflag;
3223 if (port->state->port.tty && termios.c_cflag == 0)
3224 termios.c_cflag = port->state->port.tty->termios.c_cflag;
3226 baud = serial8250_get_baud_rate(port, &termios, NULL);
3227 quot = serial8250_get_divisor(up, baud, &frac);
3229 serial8250_set_divisor(port, baud, quot, frac);
3230 serial_port_out(port, UART_LCR, up->lcr);
3231 serial8250_out_MCR(up, UART_MCR_DTR | UART_MCR_RTS);
3235 * Print a string to the serial port trying not to disturb
3236 * any possible real use of the port...
3238 * The console_lock must be held when we get here.
3240 void serial8250_console_write(struct uart_8250_port *up, const char *s,
3243 struct uart_port *port = &up->port;
3244 unsigned long flags;
3248 touch_nmi_watchdog();
3250 serial8250_rpm_get(up);
3254 else if (oops_in_progress)
3255 locked = spin_trylock_irqsave(&port->lock, flags);
3257 spin_lock_irqsave(&port->lock, flags);
3260 * First save the IER then disable the interrupts
3262 ier = serial_port_in(port, UART_IER);
3264 if (up->capabilities & UART_CAP_UUE)
3265 serial_port_out(port, UART_IER, UART_IER_UUE);
3267 serial_port_out(port, UART_IER, 0);
3269 /* check scratch reg to see if port powered off during system sleep */
3270 if (up->canary && (up->canary != serial_port_in(port, UART_SCR))) {
3271 serial8250_console_restore(up);
3275 uart_console_write(port, s, count, serial8250_console_putchar);
3278 * Finally, wait for transmitter to become empty
3279 * and restore the IER
3281 wait_for_xmitr(up, BOTH_EMPTY);
3282 serial_port_out(port, UART_IER, ier);
3285 * The receive handling will happen properly because the
3286 * receive ready bit will still be set; it is not cleared
3287 * on read. However, modem control will not, we must
3288 * call it if we have saved something in the saved flags
3289 * while processing with interrupts off.
3291 if (up->msr_saved_flags)
3292 serial8250_modem_status(up);
3295 spin_unlock_irqrestore(&port->lock, flags);
3296 serial8250_rpm_put(up);
3299 static unsigned int probe_baud(struct uart_port *port)
3301 unsigned char lcr, dll, dlm;
3304 lcr = serial_port_in(port, UART_LCR);
3305 serial_port_out(port, UART_LCR, lcr | UART_LCR_DLAB);
3306 dll = serial_port_in(port, UART_DLL);
3307 dlm = serial_port_in(port, UART_DLM);
3308 serial_port_out(port, UART_LCR, lcr);
3310 quot = (dlm << 8) | dll;
3311 return (port->uartclk / 16) / quot;
3314 int serial8250_console_setup(struct uart_port *port, char *options, bool probe)
3321 if (!port->iobase && !port->membase)
3325 uart_parse_options(options, &baud, &parity, &bits, &flow);
3327 baud = probe_baud(port);
3329 return uart_set_options(port, port->cons, baud, parity, bits, flow);
3332 #endif /* CONFIG_SERIAL_8250_CONSOLE */
3334 MODULE_LICENSE("GPL");