2 * Atheros AR933X SoC built-in UART driver
4 * Copyright (C) 2011 Gabor Juhos <juhosg@openwrt.org>
6 * Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
8 * This program is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License version 2 as published
10 * by the Free Software Foundation.
13 #include <linux/module.h>
14 #include <linux/ioport.h>
15 #include <linux/init.h>
16 #include <linux/console.h>
17 #include <linux/sysrq.h>
18 #include <linux/delay.h>
19 #include <linux/platform_device.h>
21 #include <linux/of_platform.h>
22 #include <linux/tty.h>
23 #include <linux/tty_flip.h>
24 #include <linux/serial_core.h>
25 #include <linux/serial.h>
26 #include <linux/slab.h>
28 #include <linux/irq.h>
29 #include <linux/clk.h>
31 #include <asm/div64.h>
33 #include <asm/mach-ath79/ar933x_uart.h>
35 #define DRIVER_NAME "ar933x-uart"
37 #define AR933X_UART_MAX_SCALE 0xff
38 #define AR933X_UART_MAX_STEP 0xffff
40 #define AR933X_UART_MIN_BAUD 300
41 #define AR933X_UART_MAX_BAUD 3000000
43 #define AR933X_DUMMY_STATUS_RD 0x01
45 static struct uart_driver ar933x_uart_driver;
47 struct ar933x_uart_port {
48 struct uart_port port;
49 unsigned int ier; /* shadow Interrupt Enable Register */
50 unsigned int min_baud;
51 unsigned int max_baud;
55 static inline unsigned int ar933x_uart_read(struct ar933x_uart_port *up,
58 return readl(up->port.membase + offset);
61 static inline void ar933x_uart_write(struct ar933x_uart_port *up,
62 int offset, unsigned int value)
64 writel(value, up->port.membase + offset);
67 static inline void ar933x_uart_rmw(struct ar933x_uart_port *up,
74 t = ar933x_uart_read(up, offset);
77 ar933x_uart_write(up, offset, t);
80 static inline void ar933x_uart_rmw_set(struct ar933x_uart_port *up,
84 ar933x_uart_rmw(up, offset, 0, val);
87 static inline void ar933x_uart_rmw_clear(struct ar933x_uart_port *up,
91 ar933x_uart_rmw(up, offset, val, 0);
94 static inline void ar933x_uart_start_tx_interrupt(struct ar933x_uart_port *up)
96 up->ier |= AR933X_UART_INT_TX_EMPTY;
97 ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
100 static inline void ar933x_uart_stop_tx_interrupt(struct ar933x_uart_port *up)
102 up->ier &= ~AR933X_UART_INT_TX_EMPTY;
103 ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
106 static inline void ar933x_uart_putc(struct ar933x_uart_port *up, int ch)
110 rdata = ch & AR933X_UART_DATA_TX_RX_MASK;
111 rdata |= AR933X_UART_DATA_TX_CSR;
112 ar933x_uart_write(up, AR933X_UART_DATA_REG, rdata);
115 static unsigned int ar933x_uart_tx_empty(struct uart_port *port)
117 struct ar933x_uart_port *up =
118 container_of(port, struct ar933x_uart_port, port);
122 spin_lock_irqsave(&up->port.lock, flags);
123 rdata = ar933x_uart_read(up, AR933X_UART_DATA_REG);
124 spin_unlock_irqrestore(&up->port.lock, flags);
126 return (rdata & AR933X_UART_DATA_TX_CSR) ? 0 : TIOCSER_TEMT;
129 static unsigned int ar933x_uart_get_mctrl(struct uart_port *port)
134 static void ar933x_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
138 static void ar933x_uart_start_tx(struct uart_port *port)
140 struct ar933x_uart_port *up =
141 container_of(port, struct ar933x_uart_port, port);
143 ar933x_uart_start_tx_interrupt(up);
146 static void ar933x_uart_stop_tx(struct uart_port *port)
148 struct ar933x_uart_port *up =
149 container_of(port, struct ar933x_uart_port, port);
151 ar933x_uart_stop_tx_interrupt(up);
154 static void ar933x_uart_stop_rx(struct uart_port *port)
156 struct ar933x_uart_port *up =
157 container_of(port, struct ar933x_uart_port, port);
159 up->ier &= ~AR933X_UART_INT_RX_VALID;
160 ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
163 static void ar933x_uart_break_ctl(struct uart_port *port, int break_state)
165 struct ar933x_uart_port *up =
166 container_of(port, struct ar933x_uart_port, port);
169 spin_lock_irqsave(&up->port.lock, flags);
170 if (break_state == -1)
171 ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
172 AR933X_UART_CS_TX_BREAK);
174 ar933x_uart_rmw_clear(up, AR933X_UART_CS_REG,
175 AR933X_UART_CS_TX_BREAK);
176 spin_unlock_irqrestore(&up->port.lock, flags);
180 * baudrate = (clk / (scale + 1)) * (step * (1 / 2^17))
182 static unsigned long ar933x_uart_get_baud(unsigned int clk,
189 div = (2 << 16) * (scale + 1);
198 static void ar933x_uart_get_scale_step(unsigned int clk,
210 for (tscale = 0; tscale < AR933X_UART_MAX_SCALE; tscale++) {
214 tstep = baud * (tscale + 1);
218 if (tstep > AR933X_UART_MAX_STEP)
221 diff = abs(ar933x_uart_get_baud(clk, tscale, tstep) - baud);
222 if (diff < min_diff) {
230 static void ar933x_uart_set_termios(struct uart_port *port,
231 struct ktermios *new,
232 struct ktermios *old)
234 struct ar933x_uart_port *up =
235 container_of(port, struct ar933x_uart_port, port);
238 unsigned int baud, scale, step;
240 /* Only CS8 is supported */
241 new->c_cflag &= ~CSIZE;
244 /* Only one stop bit is supported */
245 new->c_cflag &= ~CSTOPB;
248 if (new->c_cflag & PARENB) {
249 if (!(new->c_cflag & PARODD))
250 cs |= AR933X_UART_CS_PARITY_EVEN;
252 cs |= AR933X_UART_CS_PARITY_ODD;
254 cs |= AR933X_UART_CS_PARITY_NONE;
257 /* Mark/space parity is not supported */
258 new->c_cflag &= ~CMSPAR;
260 baud = uart_get_baud_rate(port, new, old, up->min_baud, up->max_baud);
261 ar933x_uart_get_scale_step(port->uartclk, baud, &scale, &step);
264 * Ok, we're now changing the port state. Do it with
265 * interrupts disabled.
267 spin_lock_irqsave(&up->port.lock, flags);
269 /* disable the UART */
270 ar933x_uart_rmw_clear(up, AR933X_UART_CS_REG,
271 AR933X_UART_CS_IF_MODE_M << AR933X_UART_CS_IF_MODE_S);
273 /* Update the per-port timeout. */
274 uart_update_timeout(port, new->c_cflag, baud);
276 up->port.ignore_status_mask = 0;
278 /* ignore all characters if CREAD is not set */
279 if ((new->c_cflag & CREAD) == 0)
280 up->port.ignore_status_mask |= AR933X_DUMMY_STATUS_RD;
282 ar933x_uart_write(up, AR933X_UART_CLOCK_REG,
283 scale << AR933X_UART_CLOCK_SCALE_S | step);
285 /* setup configuration register */
286 ar933x_uart_rmw(up, AR933X_UART_CS_REG, AR933X_UART_CS_PARITY_M, cs);
288 /* enable host interrupt */
289 ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
290 AR933X_UART_CS_HOST_INT_EN);
292 /* enable RX and TX ready overide */
293 ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
294 AR933X_UART_CS_TX_READY_ORIDE | AR933X_UART_CS_RX_READY_ORIDE);
296 /* reenable the UART */
297 ar933x_uart_rmw(up, AR933X_UART_CS_REG,
298 AR933X_UART_CS_IF_MODE_M << AR933X_UART_CS_IF_MODE_S,
299 AR933X_UART_CS_IF_MODE_DCE << AR933X_UART_CS_IF_MODE_S);
301 spin_unlock_irqrestore(&up->port.lock, flags);
303 if (tty_termios_baud_rate(new))
304 tty_termios_encode_baud_rate(new, baud, baud);
307 static void ar933x_uart_rx_chars(struct ar933x_uart_port *up)
309 struct tty_port *port = &up->port.state->port;
316 rdata = ar933x_uart_read(up, AR933X_UART_DATA_REG);
317 if ((rdata & AR933X_UART_DATA_RX_CSR) == 0)
320 /* remove the character from the FIFO */
321 ar933x_uart_write(up, AR933X_UART_DATA_REG,
322 AR933X_UART_DATA_RX_CSR);
324 up->port.icount.rx++;
325 ch = rdata & AR933X_UART_DATA_TX_RX_MASK;
327 if (uart_handle_sysrq_char(&up->port, ch))
330 if ((up->port.ignore_status_mask & AR933X_DUMMY_STATUS_RD) == 0)
331 tty_insert_flip_char(port, ch, TTY_NORMAL);
332 } while (max_count-- > 0);
334 spin_unlock(&up->port.lock);
335 tty_flip_buffer_push(port);
336 spin_lock(&up->port.lock);
339 static void ar933x_uart_tx_chars(struct ar933x_uart_port *up)
341 struct circ_buf *xmit = &up->port.state->xmit;
344 if (uart_tx_stopped(&up->port))
347 count = up->port.fifosize;
351 rdata = ar933x_uart_read(up, AR933X_UART_DATA_REG);
352 if ((rdata & AR933X_UART_DATA_TX_CSR) == 0)
355 if (up->port.x_char) {
356 ar933x_uart_putc(up, up->port.x_char);
357 up->port.icount.tx++;
362 if (uart_circ_empty(xmit))
365 ar933x_uart_putc(up, xmit->buf[xmit->tail]);
367 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
368 up->port.icount.tx++;
369 } while (--count > 0);
371 if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
372 uart_write_wakeup(&up->port);
374 if (!uart_circ_empty(xmit))
375 ar933x_uart_start_tx_interrupt(up);
378 static irqreturn_t ar933x_uart_interrupt(int irq, void *dev_id)
380 struct ar933x_uart_port *up = dev_id;
383 status = ar933x_uart_read(up, AR933X_UART_CS_REG);
384 if ((status & AR933X_UART_CS_HOST_INT) == 0)
387 spin_lock(&up->port.lock);
389 status = ar933x_uart_read(up, AR933X_UART_INT_REG);
390 status &= ar933x_uart_read(up, AR933X_UART_INT_EN_REG);
392 if (status & AR933X_UART_INT_RX_VALID) {
393 ar933x_uart_write(up, AR933X_UART_INT_REG,
394 AR933X_UART_INT_RX_VALID);
395 ar933x_uart_rx_chars(up);
398 if (status & AR933X_UART_INT_TX_EMPTY) {
399 ar933x_uart_write(up, AR933X_UART_INT_REG,
400 AR933X_UART_INT_TX_EMPTY);
401 ar933x_uart_stop_tx_interrupt(up);
402 ar933x_uart_tx_chars(up);
405 spin_unlock(&up->port.lock);
410 static int ar933x_uart_startup(struct uart_port *port)
412 struct ar933x_uart_port *up =
413 container_of(port, struct ar933x_uart_port, port);
417 ret = request_irq(up->port.irq, ar933x_uart_interrupt,
418 up->port.irqflags, dev_name(up->port.dev), up);
422 spin_lock_irqsave(&up->port.lock, flags);
424 /* Enable HOST interrupts */
425 ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
426 AR933X_UART_CS_HOST_INT_EN);
428 /* enable RX and TX ready overide */
429 ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
430 AR933X_UART_CS_TX_READY_ORIDE | AR933X_UART_CS_RX_READY_ORIDE);
432 /* Enable RX interrupts */
433 up->ier = AR933X_UART_INT_RX_VALID;
434 ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
436 spin_unlock_irqrestore(&up->port.lock, flags);
441 static void ar933x_uart_shutdown(struct uart_port *port)
443 struct ar933x_uart_port *up =
444 container_of(port, struct ar933x_uart_port, port);
446 /* Disable all interrupts */
448 ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
450 /* Disable break condition */
451 ar933x_uart_rmw_clear(up, AR933X_UART_CS_REG,
452 AR933X_UART_CS_TX_BREAK);
454 free_irq(up->port.irq, up);
457 static const char *ar933x_uart_type(struct uart_port *port)
459 return (port->type == PORT_AR933X) ? "AR933X UART" : NULL;
462 static void ar933x_uart_release_port(struct uart_port *port)
464 /* Nothing to release ... */
467 static int ar933x_uart_request_port(struct uart_port *port)
469 /* UARTs always present */
473 static void ar933x_uart_config_port(struct uart_port *port, int flags)
475 if (flags & UART_CONFIG_TYPE)
476 port->type = PORT_AR933X;
479 static int ar933x_uart_verify_port(struct uart_port *port,
480 struct serial_struct *ser)
482 struct ar933x_uart_port *up =
483 container_of(port, struct ar933x_uart_port, port);
485 if (ser->type != PORT_UNKNOWN &&
486 ser->type != PORT_AR933X)
489 if (ser->irq < 0 || ser->irq >= NR_IRQS)
492 if (ser->baud_base < up->min_baud ||
493 ser->baud_base > up->max_baud)
499 static struct uart_ops ar933x_uart_ops = {
500 .tx_empty = ar933x_uart_tx_empty,
501 .set_mctrl = ar933x_uart_set_mctrl,
502 .get_mctrl = ar933x_uart_get_mctrl,
503 .stop_tx = ar933x_uart_stop_tx,
504 .start_tx = ar933x_uart_start_tx,
505 .stop_rx = ar933x_uart_stop_rx,
506 .break_ctl = ar933x_uart_break_ctl,
507 .startup = ar933x_uart_startup,
508 .shutdown = ar933x_uart_shutdown,
509 .set_termios = ar933x_uart_set_termios,
510 .type = ar933x_uart_type,
511 .release_port = ar933x_uart_release_port,
512 .request_port = ar933x_uart_request_port,
513 .config_port = ar933x_uart_config_port,
514 .verify_port = ar933x_uart_verify_port,
517 #ifdef CONFIG_SERIAL_AR933X_CONSOLE
518 static struct ar933x_uart_port *
519 ar933x_console_ports[CONFIG_SERIAL_AR933X_NR_UARTS];
521 static void ar933x_uart_wait_xmitr(struct ar933x_uart_port *up)
524 unsigned int timeout = 60000;
526 /* Wait up to 60ms for the character(s) to be sent. */
528 status = ar933x_uart_read(up, AR933X_UART_DATA_REG);
532 } while ((status & AR933X_UART_DATA_TX_CSR) == 0);
535 static void ar933x_uart_console_putchar(struct uart_port *port, int ch)
537 struct ar933x_uart_port *up =
538 container_of(port, struct ar933x_uart_port, port);
540 ar933x_uart_wait_xmitr(up);
541 ar933x_uart_putc(up, ch);
544 static void ar933x_uart_console_write(struct console *co, const char *s,
547 struct ar933x_uart_port *up = ar933x_console_ports[co->index];
552 local_irq_save(flags);
556 else if (oops_in_progress)
557 locked = spin_trylock(&up->port.lock);
559 spin_lock(&up->port.lock);
562 * First save the IER then disable the interrupts
564 int_en = ar933x_uart_read(up, AR933X_UART_INT_EN_REG);
565 ar933x_uart_write(up, AR933X_UART_INT_EN_REG, 0);
567 uart_console_write(&up->port, s, count, ar933x_uart_console_putchar);
570 * Finally, wait for transmitter to become empty
571 * and restore the IER
573 ar933x_uart_wait_xmitr(up);
574 ar933x_uart_write(up, AR933X_UART_INT_EN_REG, int_en);
576 ar933x_uart_write(up, AR933X_UART_INT_REG, AR933X_UART_INT_ALLINTS);
579 spin_unlock(&up->port.lock);
581 local_irq_restore(flags);
584 static int ar933x_uart_console_setup(struct console *co, char *options)
586 struct ar933x_uart_port *up;
592 if (co->index < 0 || co->index >= CONFIG_SERIAL_AR933X_NR_UARTS)
595 up = ar933x_console_ports[co->index];
600 uart_parse_options(options, &baud, &parity, &bits, &flow);
602 return uart_set_options(&up->port, co, baud, parity, bits, flow);
605 static struct console ar933x_uart_console = {
607 .write = ar933x_uart_console_write,
608 .device = uart_console_device,
609 .setup = ar933x_uart_console_setup,
610 .flags = CON_PRINTBUFFER,
612 .data = &ar933x_uart_driver,
614 #endif /* CONFIG_SERIAL_AR933X_CONSOLE */
616 static struct uart_driver ar933x_uart_driver = {
617 .owner = THIS_MODULE,
618 .driver_name = DRIVER_NAME,
619 .dev_name = "ttyATH",
620 .nr = CONFIG_SERIAL_AR933X_NR_UARTS,
621 .cons = NULL, /* filled in runtime */
624 static int ar933x_uart_probe(struct platform_device *pdev)
626 struct ar933x_uart_port *up;
627 struct uart_port *port;
628 struct resource *mem_res;
629 struct resource *irq_res;
630 struct device_node *np;
635 np = pdev->dev.of_node;
636 if (IS_ENABLED(CONFIG_OF) && np) {
637 id = of_alias_get_id(np, "serial");
639 dev_err(&pdev->dev, "unable to get alias id, err=%d\n",
649 if (id >= CONFIG_SERIAL_AR933X_NR_UARTS)
652 irq_res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
654 dev_err(&pdev->dev, "no IRQ resource\n");
658 up = devm_kzalloc(&pdev->dev, sizeof(struct ar933x_uart_port),
663 up->clk = devm_clk_get(&pdev->dev, "uart");
664 if (IS_ERR(up->clk)) {
665 dev_err(&pdev->dev, "unable to get UART clock\n");
666 return PTR_ERR(up->clk);
671 mem_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
672 port->membase = devm_ioremap_resource(&pdev->dev, mem_res);
673 if (IS_ERR(port->membase))
674 return PTR_ERR(port->membase);
676 ret = clk_prepare_enable(up->clk);
680 port->uartclk = clk_get_rate(up->clk);
681 if (!port->uartclk) {
683 goto err_disable_clk;
686 port->mapbase = mem_res->start;
688 port->irq = irq_res->start;
689 port->dev = &pdev->dev;
690 port->type = PORT_AR933X;
691 port->iotype = UPIO_MEM32;
694 port->fifosize = AR933X_UART_FIFO_SIZE;
695 port->ops = &ar933x_uart_ops;
697 baud = ar933x_uart_get_baud(port->uartclk, AR933X_UART_MAX_SCALE, 1);
698 up->min_baud = max_t(unsigned int, baud, AR933X_UART_MIN_BAUD);
700 baud = ar933x_uart_get_baud(port->uartclk, 0, AR933X_UART_MAX_STEP);
701 up->max_baud = min_t(unsigned int, baud, AR933X_UART_MAX_BAUD);
703 #ifdef CONFIG_SERIAL_AR933X_CONSOLE
704 ar933x_console_ports[up->port.line] = up;
707 ret = uart_add_one_port(&ar933x_uart_driver, &up->port);
709 goto err_disable_clk;
711 platform_set_drvdata(pdev, up);
715 clk_disable_unprepare(up->clk);
719 static int ar933x_uart_remove(struct platform_device *pdev)
721 struct ar933x_uart_port *up;
723 up = platform_get_drvdata(pdev);
726 uart_remove_one_port(&ar933x_uart_driver, &up->port);
727 clk_disable_unprepare(up->clk);
734 static const struct of_device_id ar933x_uart_of_ids[] = {
735 { .compatible = "qca,ar9330-uart" },
738 MODULE_DEVICE_TABLE(of, ar933x_uart_of_ids);
741 static struct platform_driver ar933x_uart_platform_driver = {
742 .probe = ar933x_uart_probe,
743 .remove = ar933x_uart_remove,
746 .of_match_table = of_match_ptr(ar933x_uart_of_ids),
750 static int __init ar933x_uart_init(void)
754 #ifdef CONFIG_SERIAL_AR933X_CONSOLE
755 ar933x_uart_driver.cons = &ar933x_uart_console;
758 ret = uart_register_driver(&ar933x_uart_driver);
762 ret = platform_driver_register(&ar933x_uart_platform_driver);
764 goto err_unregister_uart_driver;
768 err_unregister_uart_driver:
769 uart_unregister_driver(&ar933x_uart_driver);
774 static void __exit ar933x_uart_exit(void)
776 platform_driver_unregister(&ar933x_uart_platform_driver);
777 uart_unregister_driver(&ar933x_uart_driver);
780 module_init(ar933x_uart_init);
781 module_exit(ar933x_uart_exit);
783 MODULE_DESCRIPTION("Atheros AR933X UART driver");
784 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
785 MODULE_LICENSE("GPL v2");
786 MODULE_ALIAS("platform:" DRIVER_NAME);