drivers/tty/serial/clps711x.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  *  Driver for CLPS711x serial ports
   4  *
   5  *  Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
   6  *
   7  *  Copyright 1999 ARM Limited
   8  *  Copyright (C) 2000 Deep Blue Solutions Ltd.
   9  */
  10
  11 #include <linux/module.h>
  12 #include <linux/device.h>
  13 #include <linux/console.h>
  14 #include <linux/serial_core.h>
  15 #include <linux/serial.h>
  16 #include <linux/clk.h>
  17 #include <linux/io.h>
  18 #include <linux/tty.h>
  19 #include <linux/tty_flip.h>
  20 #include <linux/ioport.h>
  21 #include <linux/of.h>
  22 #include <linux/platform_device.h>
  23 #include <linux/regmap.h>
  24
  25 #include <linux/mfd/syscon.h>
  26 #include <linux/mfd/syscon/clps711x.h>
  27
  28 #include "serial_mctrl_gpio.h"
  29
  30 #define UART_CLPS711X_DEVNAME   "ttyCL"
  31 #define UART_CLPS711X_NR        2
  32 #define UART_CLPS711X_MAJOR     204
  33 #define UART_CLPS711X_MINOR     40
  34
  35 #define UARTDR_OFFSET           (0x00)
  36 #define UBRLCR_OFFSET           (0x40)
  37
  38 #define UARTDR_FRMERR           (1 << 8)
  39 #define UARTDR_PARERR           (1 << 9)
  40 #define UARTDR_OVERR            (1 << 10)
  41
  42 #define UBRLCR_BAUD_MASK        ((1 << 12) - 1)
  43 #define UBRLCR_BREAK            (1 << 12)
  44 #define UBRLCR_PRTEN            (1 << 13)
  45 #define UBRLCR_EVENPRT          (1 << 14)
  46 #define UBRLCR_XSTOP            (1 << 15)
  47 #define UBRLCR_FIFOEN           (1 << 16)
  48 #define UBRLCR_WRDLEN5          (0 << 17)
  49 #define UBRLCR_WRDLEN6          (1 << 17)
  50 #define UBRLCR_WRDLEN7          (2 << 17)
  51 #define UBRLCR_WRDLEN8          (3 << 17)
  52 #define UBRLCR_WRDLEN_MASK      (3 << 17)
  53
  54 struct clps711x_port {
  55         struct uart_port        port;
  56         unsigned int            tx_enabled;
  57         int                     rx_irq;
  58         struct regmap           *syscon;
  59         struct mctrl_gpios      *gpios;
  60 };
  61
  62 static struct uart_driver clps711x_uart = {
  63         .owner          = THIS_MODULE,
  64         .driver_name    = UART_CLPS711X_DEVNAME,
  65         .dev_name       = UART_CLPS711X_DEVNAME,
  66         .major          = UART_CLPS711X_MAJOR,
  67         .minor          = UART_CLPS711X_MINOR,
  68         .nr             = UART_CLPS711X_NR,
  69 };
  70
  71 static void uart_clps711x_stop_tx(struct uart_port *port)
  72 {
  73         struct clps711x_port *s = dev_get_drvdata(port->dev);
  74
  75         if (s->tx_enabled) {
  76                 disable_irq(port->irq);
  77                 s->tx_enabled = 0;
  78         }
  79 }
  80
  81 static void uart_clps711x_start_tx(struct uart_port *port)
  82 {
  83         struct clps711x_port *s = dev_get_drvdata(port->dev);
  84
  85         if (!s->tx_enabled) {
  86                 s->tx_enabled = 1;
  87                 enable_irq(port->irq);
  88         }
  89 }
  90
  91 static irqreturn_t uart_clps711x_int_rx(int irq, void *dev_id)
  92 {
  93         struct uart_port *port = dev_id;
  94         struct clps711x_port *s = dev_get_drvdata(port->dev);
  95         unsigned int status;
  96         u16 ch;
  97         u8 flg;
  98
  99         for (;;) {
 100                 u32 sysflg = 0;
 101
 102                 regmap_read(s->syscon, SYSFLG_OFFSET, &sysflg);
 103                 if (sysflg & SYSFLG_URXFE)
 104                         break;
 105
 106                 ch = readw(port->membase + UARTDR_OFFSET);
 107                 status = ch & (UARTDR_FRMERR | UARTDR_PARERR | UARTDR_OVERR);
 108                 ch &= 0xff;
 109
 110                 port->icount.rx++;
 111                 flg = TTY_NORMAL;
 112
 113                 if (unlikely(status)) {
 114                         if (status & UARTDR_PARERR)
 115                                 port->icount.parity++;
 116                         else if (status & UARTDR_FRMERR)
 117                                 port->icount.frame++;
 118                         else if (status & UARTDR_OVERR)
 119                                 port->icount.overrun++;
 120
 121                         status &= port->read_status_mask;
 122
 123                         if (status & UARTDR_PARERR)
 124                                 flg = TTY_PARITY;
 125                         else if (status & UARTDR_FRMERR)
 126                                 flg = TTY_FRAME;
 127                         else if (status & UARTDR_OVERR)
 128                                 flg = TTY_OVERRUN;
 129                 }
 130
 131                 if (uart_handle_sysrq_char(port, ch))
 132                         continue;
 133
 134                 if (status & port->ignore_status_mask)
 135                         continue;
 136
 137                 uart_insert_char(port, status, UARTDR_OVERR, ch, flg);
 138         }
 139
 140         tty_flip_buffer_push(&port->state->port);
 141
 142         return IRQ_HANDLED;
 143 }
 144
 145 static irqreturn_t uart_clps711x_int_tx(int irq, void *dev_id)
 146 {
 147         struct uart_port *port = dev_id;
 148         struct clps711x_port *s = dev_get_drvdata(port->dev);
 149         struct circ_buf *xmit = &port->state->xmit;
 150
 151         if (port->x_char) {
 152                 writew(port->x_char, port->membase + UARTDR_OFFSET);
 153                 port->icount.tx++;
 154                 port->x_char = 0;
 155                 return IRQ_HANDLED;
 156         }
 157
 158         if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
 159                 if (s->tx_enabled) {
 160                         disable_irq_nosync(port->irq);
 161                         s->tx_enabled = 0;
 162                 }
 163                 return IRQ_HANDLED;
 164         }
 165
 166         while (!uart_circ_empty(xmit)) {
 167                 u32 sysflg = 0;
 168
 169                 writew(xmit->buf[xmit->tail], port->membase + UARTDR_OFFSET);
 170                 uart_xmit_advance(port, 1);
 171
 172                 regmap_read(s->syscon, SYSFLG_OFFSET, &sysflg);
 173                 if (sysflg & SYSFLG_UTXFF)
 174                         break;
 175         }
 176
 177         if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 178                 uart_write_wakeup(port);
 179
 180         return IRQ_HANDLED;
 181 }
 182
 183 static unsigned int uart_clps711x_tx_empty(struct uart_port *port)
 184 {
 185         struct clps711x_port *s = dev_get_drvdata(port->dev);
 186         u32 sysflg = 0;
 187
 188         regmap_read(s->syscon, SYSFLG_OFFSET, &sysflg);
 189
 190         return (sysflg & SYSFLG_UBUSY) ? 0 : TIOCSER_TEMT;
 191 }
 192
 193 static unsigned int uart_clps711x_get_mctrl(struct uart_port *port)
 194 {
 195         unsigned int result = TIOCM_DSR | TIOCM_CTS | TIOCM_CAR;
 196         struct clps711x_port *s = dev_get_drvdata(port->dev);
 197
 198         return mctrl_gpio_get(s->gpios, &result);
 199 }
 200
 201 static void uart_clps711x_set_mctrl(struct uart_port *port, unsigned int mctrl)
 202 {
 203         struct clps711x_port *s = dev_get_drvdata(port->dev);
 204
 205         mctrl_gpio_set(s->gpios, mctrl);
 206 }
 207
 208 static void uart_clps711x_break_ctl(struct uart_port *port, int break_state)
 209 {
 210         unsigned int ubrlcr;
 211
 212         ubrlcr = readl(port->membase + UBRLCR_OFFSET);
 213         if (break_state)
 214                 ubrlcr |= UBRLCR_BREAK;
 215         else
 216                 ubrlcr &= ~UBRLCR_BREAK;
 217         writel(ubrlcr, port->membase + UBRLCR_OFFSET);
 218 }
 219
 220 static void uart_clps711x_set_ldisc(struct uart_port *port,
 221                                     struct ktermios *termios)
 222 {
 223         if (!port->line) {
 224                 struct clps711x_port *s = dev_get_drvdata(port->dev);
 225
 226                 regmap_update_bits(s->syscon, SYSCON_OFFSET, SYSCON1_SIREN,
 227                                    (termios->c_line == N_IRDA) ? SYSCON1_SIREN : 0);
 228         }
 229 }
 230
 231 static int uart_clps711x_startup(struct uart_port *port)
 232 {
 233         struct clps711x_port *s = dev_get_drvdata(port->dev);
 234
 235         /* Disable break */
 236         writel(readl(port->membase + UBRLCR_OFFSET) & ~UBRLCR_BREAK,
 237                port->membase + UBRLCR_OFFSET);
 238
 239         /* Enable the port */
 240         return regmap_update_bits(s->syscon, SYSCON_OFFSET,
 241                                   SYSCON_UARTEN, SYSCON_UARTEN);
 242 }
 243
 244 static void uart_clps711x_shutdown(struct uart_port *port)
 245 {
 246         struct clps711x_port *s = dev_get_drvdata(port->dev);
 247
 248         /* Disable the port */
 249         regmap_update_bits(s->syscon, SYSCON_OFFSET, SYSCON_UARTEN, 0);
 250 }
 251
 252 static void uart_clps711x_set_termios(struct uart_port *port,
 253                                       struct ktermios *termios,
 254                                       const struct ktermios *old)
 255 {
 256         u32 ubrlcr;
 257         unsigned int baud, quot;
 258
 259         /* Mask termios capabilities we don't support */
 260         termios->c_cflag &= ~CMSPAR;
 261         termios->c_iflag &= ~(BRKINT | IGNBRK);
 262
 263         /* Ask the core to calculate the divisor for us */
 264         baud = uart_get_baud_rate(port, termios, old, port->uartclk / 4096,
 265                                                       port->uartclk / 16);
 266         quot = uart_get_divisor(port, baud);
 267
 268         switch (termios->c_cflag & CSIZE) {
 269         case CS5:
 270                 ubrlcr = UBRLCR_WRDLEN5;
 271                 break;
 272         case CS6:
 273                 ubrlcr = UBRLCR_WRDLEN6;
 274                 break;
 275         case CS7:
 276                 ubrlcr = UBRLCR_WRDLEN7;
 277                 break;
 278         case CS8:
 279         default:
 280                 ubrlcr = UBRLCR_WRDLEN8;
 281                 break;
 282         }
 283
 284         if (termios->c_cflag & CSTOPB)
 285                 ubrlcr |= UBRLCR_XSTOP;
 286
 287         if (termios->c_cflag & PARENB) {
 288                 ubrlcr |= UBRLCR_PRTEN;
 289                 if (!(termios->c_cflag & PARODD))
 290                         ubrlcr |= UBRLCR_EVENPRT;
 291         }
 292
 293         /* Enable FIFO */
 294         ubrlcr |= UBRLCR_FIFOEN;
 295
 296         /* Set read status mask */
 297         port->read_status_mask = UARTDR_OVERR;
 298         if (termios->c_iflag & INPCK)
 299                 port->read_status_mask |= UARTDR_PARERR | UARTDR_FRMERR;
 300
 301         /* Set status ignore mask */
 302         port->ignore_status_mask = 0;
 303         if (!(termios->c_cflag & CREAD))
 304                 port->ignore_status_mask |= UARTDR_OVERR | UARTDR_PARERR |
 305                                             UARTDR_FRMERR;
 306
 307         uart_update_timeout(port, termios->c_cflag, baud);
 308
 309         writel(ubrlcr | (quot - 1), port->membase + UBRLCR_OFFSET);
 310 }
 311
 312 static const char *uart_clps711x_type(struct uart_port *port)
 313 {
 314         return (port->type == PORT_CLPS711X) ? "CLPS711X" : NULL;
 315 }
 316
 317 static void uart_clps711x_config_port(struct uart_port *port, int flags)
 318 {
 319         if (flags & UART_CONFIG_TYPE)
 320                 port->type = PORT_CLPS711X;
 321 }
 322
 323 static void uart_clps711x_nop_void(struct uart_port *port)
 324 {
 325 }
 326
 327 static int uart_clps711x_nop_int(struct uart_port *port)
 328 {
 329         return 0;
 330 }
 331
 332 static const struct uart_ops uart_clps711x_ops = {
 333         .tx_empty       = uart_clps711x_tx_empty,
 334         .set_mctrl      = uart_clps711x_set_mctrl,
 335         .get_mctrl      = uart_clps711x_get_mctrl,
 336         .stop_tx        = uart_clps711x_stop_tx,
 337         .start_tx       = uart_clps711x_start_tx,
 338         .stop_rx        = uart_clps711x_nop_void,
 339         .break_ctl      = uart_clps711x_break_ctl,
 340         .set_ldisc      = uart_clps711x_set_ldisc,
 341         .startup        = uart_clps711x_startup,
 342         .shutdown       = uart_clps711x_shutdown,
 343         .set_termios    = uart_clps711x_set_termios,
 344         .type           = uart_clps711x_type,
 345         .config_port    = uart_clps711x_config_port,
 346         .release_port   = uart_clps711x_nop_void,
 347         .request_port   = uart_clps711x_nop_int,
 348 };
 349
 350 #ifdef CONFIG_SERIAL_CLPS711X_CONSOLE
 351 static void uart_clps711x_console_putchar(struct uart_port *port, unsigned char ch)
 352 {
 353         struct clps711x_port *s = dev_get_drvdata(port->dev);
 354         u32 sysflg = 0;
 355
 356         /* Wait for FIFO is not full */
 357         do {
 358                 regmap_read(s->syscon, SYSFLG_OFFSET, &sysflg);
 359         } while (sysflg & SYSFLG_UTXFF);
 360
 361         writew(ch, port->membase + UARTDR_OFFSET);
 362 }
 363
 364 static void uart_clps711x_console_write(struct console *co, const char *c,
 365                                         unsigned n)
 366 {
 367         struct uart_port *port = clps711x_uart.state[co->index].uart_port;
 368         struct clps711x_port *s = dev_get_drvdata(port->dev);
 369         u32 sysflg = 0;
 370
 371         uart_console_write(port, c, n, uart_clps711x_console_putchar);
 372
 373         /* Wait for transmitter to become empty */
 374         do {
 375                 regmap_read(s->syscon, SYSFLG_OFFSET, &sysflg);
 376         } while (sysflg & SYSFLG_UBUSY);
 377 }
 378
 379 static int uart_clps711x_console_setup(struct console *co, char *options)
 380 {
 381         int baud = 38400, bits = 8, parity = 'n', flow = 'n';
 382         int ret, index = co->index;
 383         struct clps711x_port *s;
 384         struct uart_port *port;
 385         unsigned int quot;
 386         u32 ubrlcr;
 387
 388         if (index < 0 || index >= UART_CLPS711X_NR)
 389                 return -EINVAL;
 390
 391         port = clps711x_uart.state[index].uart_port;
 392         if (!port)
 393                 return -ENODEV;
 394
 395         s = dev_get_drvdata(port->dev);
 396
 397         if (!options) {
 398                 u32 syscon = 0;
 399
 400                 regmap_read(s->syscon, SYSCON_OFFSET, &syscon);
 401                 if (syscon & SYSCON_UARTEN) {
 402                         ubrlcr = readl(port->membase + UBRLCR_OFFSET);
 403
 404                         if (ubrlcr & UBRLCR_PRTEN) {
 405                                 if (ubrlcr & UBRLCR_EVENPRT)
 406                                         parity = 'e';
 407                                 else
 408                                         parity = 'o';
 409                         }
 410
 411                         if ((ubrlcr & UBRLCR_WRDLEN_MASK) == UBRLCR_WRDLEN7)
 412                                 bits = 7;
 413
 414                         quot = ubrlcr & UBRLCR_BAUD_MASK;
 415                         baud = port->uartclk / (16 * (quot + 1));
 416                 }
 417         } else
 418                 uart_parse_options(options, &baud, &parity, &bits, &flow);
 419
 420         ret = uart_set_options(port, co, baud, parity, bits, flow);
 421         if (ret)
 422                 return ret;
 423
 424         return regmap_update_bits(s->syscon, SYSCON_OFFSET,
 425                                   SYSCON_UARTEN, SYSCON_UARTEN);
 426 }
 427
 428 static struct console clps711x_console = {
 429         .name   = UART_CLPS711X_DEVNAME,
 430         .device = uart_console_device,
 431         .write  = uart_clps711x_console_write,
 432         .setup  = uart_clps711x_console_setup,
 433         .flags  = CON_PRINTBUFFER,
 434         .index  = -1,
 435 };
 436 #endif
 437
 438 static int uart_clps711x_probe(struct platform_device *pdev)
 439 {
 440         struct device_node *np = pdev->dev.of_node;
 441         struct clps711x_port *s;
 442         struct resource *res;
 443         struct clk *uart_clk;
 444         int irq, ret;
 445
 446         s = devm_kzalloc(&pdev->dev, sizeof(*s), GFP_KERNEL);
 447         if (!s)
 448                 return -ENOMEM;
 449
 450         uart_clk = devm_clk_get(&pdev->dev, NULL);
 451         if (IS_ERR(uart_clk))
 452                 return PTR_ERR(uart_clk);
 453
 454         s->port.membase = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
 455         if (IS_ERR(s->port.membase))
 456                 return PTR_ERR(s->port.membase);
 457
 458         irq = platform_get_irq(pdev, 0);
 459         if (irq < 0)
 460                 return irq;
 461         s->port.irq = irq;
 462
 463         s->rx_irq = platform_get_irq(pdev, 1);
 464         if (s->rx_irq < 0)
 465                 return s->rx_irq;
 466
 467         s->syscon = syscon_regmap_lookup_by_phandle(np, "syscon");
 468         if (IS_ERR(s->syscon))
 469                 return PTR_ERR(s->syscon);
 470
 471         s->port.line            = of_alias_get_id(np, "serial");
 472         s->port.dev             = &pdev->dev;
 473         s->port.iotype          = UPIO_MEM32;
 474         s->port.mapbase         = res->start;
 475         s->port.type            = PORT_CLPS711X;
 476         s->port.fifosize        = 16;
 477         s->port.has_sysrq       = IS_ENABLED(CONFIG_SERIAL_CLPS711X_CONSOLE);
 478         s->port.flags           = UPF_SKIP_TEST | UPF_FIXED_TYPE;
 479         s->port.uartclk         = clk_get_rate(uart_clk);
 480         s->port.ops             = &uart_clps711x_ops;
 481
 482         platform_set_drvdata(pdev, s);
 483
 484         s->gpios = mctrl_gpio_init_noauto(&pdev->dev, 0);
 485         if (IS_ERR(s->gpios))
 486             return PTR_ERR(s->gpios);
 487
 488         ret = uart_add_one_port(&clps711x_uart, &s->port);
 489         if (ret)
 490                 return ret;
 491
 492         /* Disable port */
 493         if (!uart_console(&s->port))
 494                 regmap_update_bits(s->syscon, SYSCON_OFFSET, SYSCON_UARTEN, 0);
 495
 496         s->tx_enabled = 1;
 497
 498         ret = devm_request_irq(&pdev->dev, s->port.irq, uart_clps711x_int_tx, 0,
 499                                dev_name(&pdev->dev), &s->port);
 500         if (ret) {
 501                 uart_remove_one_port(&clps711x_uart, &s->port);
 502                 return ret;
 503         }
 504
 505         ret = devm_request_irq(&pdev->dev, s->rx_irq, uart_clps711x_int_rx, 0,
 506                                dev_name(&pdev->dev), &s->port);
 507         if (ret)
 508                 uart_remove_one_port(&clps711x_uart, &s->port);
 509
 510         return ret;
 511 }
 512
 513 static void uart_clps711x_remove(struct platform_device *pdev)
 514 {
 515         struct clps711x_port *s = platform_get_drvdata(pdev);
 516
 517         uart_remove_one_port(&clps711x_uart, &s->port);
 518 }
 519
 520 static const struct of_device_id __maybe_unused clps711x_uart_dt_ids[] = {
 521         { .compatible = "cirrus,ep7209-uart", },
 522         { }
 523 };
 524 MODULE_DEVICE_TABLE(of, clps711x_uart_dt_ids);
 525
 526 static struct platform_driver clps711x_uart_platform = {
 527         .driver = {
 528                 .name           = "clps711x-uart",
 529                 .of_match_table = of_match_ptr(clps711x_uart_dt_ids),
 530         },
 531         .probe  = uart_clps711x_probe,
 532         .remove_new = uart_clps711x_remove,
 533 };
 534
 535 static int __init uart_clps711x_init(void)
 536 {
 537         int ret;
 538
 539 #ifdef CONFIG_SERIAL_CLPS711X_CONSOLE
 540         clps711x_uart.cons = &clps711x_console;
 541         clps711x_console.data = &clps711x_uart;
 542 #endif
 543
 544         ret = uart_register_driver(&clps711x_uart);
 545         if (ret)
 546                 return ret;
 547
 548         return platform_driver_register(&clps711x_uart_platform);
 549 }
 550 module_init(uart_clps711x_init);
 551
 552 static void __exit uart_clps711x_exit(void)
 553 {
 554         platform_driver_unregister(&clps711x_uart_platform);
 555         uart_unregister_driver(&clps711x_uart);
 556 }
 557 module_exit(uart_clps711x_exit);
 558
 559 MODULE_AUTHOR("Deep Blue Solutions Ltd");
 560 MODULE_DESCRIPTION("CLPS711X serial driver");
 561 MODULE_LICENSE("GPL");