kernel/drivers/tty/serial/digicolor-usart.c

   1 /*
   2  *  Driver for Conexant Digicolor serial ports (USART)
   3  *
   4  * Author: Baruch Siach <baruch@tkos.co.il>
   5  *
   6  * Copyright (C) 2014 Paradox Innovation Ltd.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  */
  13
  14 #include <linux/module.h>
  15 #include <linux/console.h>
  16 #include <linux/serial_core.h>
  17 #include <linux/serial.h>
  18 #include <linux/clk.h>
  19 #include <linux/io.h>
  20 #include <linux/tty.h>
  21 #include <linux/tty_flip.h>
  22 #include <linux/of.h>
  23 #include <linux/platform_device.h>
  24 #include <linux/workqueue.h>
  25
  26 #define UA_ENABLE                       0x00
  27 #define UA_ENABLE_ENABLE                BIT(0)
  28
  29 #define UA_CONTROL                      0x01
  30 #define UA_CONTROL_RX_ENABLE            BIT(0)
  31 #define UA_CONTROL_TX_ENABLE            BIT(1)
  32 #define UA_CONTROL_SOFT_RESET           BIT(2)
  33
  34 #define UA_STATUS                       0x02
  35 #define UA_STATUS_PARITY_ERR            BIT(0)
  36 #define UA_STATUS_FRAME_ERR             BIT(1)
  37 #define UA_STATUS_OVERRUN_ERR           BIT(2)
  38 #define UA_STATUS_TX_READY              BIT(6)
  39
  40 #define UA_CONFIG                       0x03
  41 #define UA_CONFIG_CHAR_LEN              BIT(0)
  42 #define UA_CONFIG_STOP_BITS             BIT(1)
  43 #define UA_CONFIG_PARITY                BIT(2)
  44 #define UA_CONFIG_ODD_PARITY            BIT(4)
  45
  46 #define UA_EMI_REC                      0x04
  47
  48 #define UA_HBAUD_LO                     0x08
  49 #define UA_HBAUD_HI                     0x09
  50
  51 #define UA_STATUS_FIFO                  0x0a
  52 #define UA_STATUS_FIFO_RX_EMPTY         BIT(2)
  53 #define UA_STATUS_FIFO_RX_INT_ALMOST    BIT(3)
  54 #define UA_STATUS_FIFO_TX_FULL          BIT(4)
  55 #define UA_STATUS_FIFO_TX_INT_ALMOST    BIT(7)
  56
  57 #define UA_CONFIG_FIFO                  0x0b
  58 #define UA_CONFIG_FIFO_RX_THRESH        7
  59 #define UA_CONFIG_FIFO_RX_FIFO_MODE     BIT(3)
  60 #define UA_CONFIG_FIFO_TX_FIFO_MODE     BIT(7)
  61
  62 #define UA_INTFLAG_CLEAR                0x1c
  63 #define UA_INTFLAG_SET                  0x1d
  64 #define UA_INT_ENABLE                   0x1e
  65 #define UA_INT_STATUS                   0x1f
  66
  67 #define UA_INT_TX                       BIT(0)
  68 #define UA_INT_RX                       BIT(1)
  69
  70 #define DIGICOLOR_USART_NR              3
  71
  72 /*
  73  * We use the 16 bytes hardware FIFO to buffer Rx traffic. Rx interrupt is
  74  * only produced when the FIFO is filled more than a certain configurable
  75  * threshold. Unfortunately, there is no way to set this threshold below half
  76  * FIFO. This means that we must periodically poll the FIFO status register to
  77  * see whether there are waiting Rx bytes.
  78  */
  79
  80 struct digicolor_port {
  81         struct uart_port port;
  82         struct delayed_work rx_poll_work;
  83 };
  84
  85 static struct uart_port *digicolor_ports[DIGICOLOR_USART_NR];
  86
  87 static bool digicolor_uart_tx_full(struct uart_port *port)
  88 {
  89         return !!(readb_relaxed(port->membase + UA_STATUS_FIFO) &
  90                   UA_STATUS_FIFO_TX_FULL);
  91 }
  92
  93 static bool digicolor_uart_rx_empty(struct uart_port *port)
  94 {
  95         return !!(readb_relaxed(port->membase + UA_STATUS_FIFO) &
  96                   UA_STATUS_FIFO_RX_EMPTY);
  97 }
  98
  99 static void digicolor_uart_stop_tx(struct uart_port *port)
 100 {
 101         u8 int_enable = readb_relaxed(port->membase + UA_INT_ENABLE);
 102
 103         int_enable &= ~UA_INT_TX;
 104         writeb_relaxed(int_enable, port->membase + UA_INT_ENABLE);
 105 }
 106
 107 static void digicolor_uart_start_tx(struct uart_port *port)
 108 {
 109         u8 int_enable = readb_relaxed(port->membase + UA_INT_ENABLE);
 110
 111         int_enable |= UA_INT_TX;
 112         writeb_relaxed(int_enable, port->membase + UA_INT_ENABLE);
 113 }
 114
 115 static void digicolor_uart_stop_rx(struct uart_port *port)
 116 {
 117         u8 int_enable = readb_relaxed(port->membase + UA_INT_ENABLE);
 118
 119         int_enable &= ~UA_INT_RX;
 120         writeb_relaxed(int_enable, port->membase + UA_INT_ENABLE);
 121 }
 122
 123 static void digicolor_rx_poll(struct work_struct *work)
 124 {
 125         struct digicolor_port *dp =
 126                 container_of(to_delayed_work(work),
 127                              struct digicolor_port, rx_poll_work);
 128
 129         if (!digicolor_uart_rx_empty(&dp->port))
 130                 /* force RX interrupt */
 131                 writeb_relaxed(UA_INT_RX, dp->port.membase + UA_INTFLAG_SET);
 132
 133         schedule_delayed_work(&dp->rx_poll_work, msecs_to_jiffies(100));
 134 }
 135
 136 static void digicolor_uart_rx(struct uart_port *port)
 137 {
 138         unsigned long flags;
 139
 140         spin_lock_irqsave(&port->lock, flags);
 141
 142         while (1) {
 143                 u8 status, ch;
 144                 unsigned int ch_flag;
 145
 146                 if (digicolor_uart_rx_empty(port))
 147                         break;
 148
 149                 ch = readb_relaxed(port->membase + UA_EMI_REC);
 150                 status = readb_relaxed(port->membase + UA_STATUS);
 151
 152                 port->icount.rx++;
 153                 ch_flag = TTY_NORMAL;
 154
 155                 if (status) {
 156                         if (status & UA_STATUS_PARITY_ERR)
 157                                 port->icount.parity++;
 158                         else if (status & UA_STATUS_FRAME_ERR)
 159                                 port->icount.frame++;
 160                         else if (status & UA_STATUS_OVERRUN_ERR)
 161                                 port->icount.overrun++;
 162
 163                         status &= port->read_status_mask;
 164
 165                         if (status & UA_STATUS_PARITY_ERR)
 166                                 ch_flag = TTY_PARITY;
 167                         else if (status & UA_STATUS_FRAME_ERR)
 168                                 ch_flag = TTY_FRAME;
 169                         else if (status & UA_STATUS_OVERRUN_ERR)
 170                                 ch_flag = TTY_OVERRUN;
 171                 }
 172
 173                 if (status & port->ignore_status_mask)
 174                         continue;
 175
 176                 uart_insert_char(port, status, UA_STATUS_OVERRUN_ERR, ch,
 177                                  ch_flag);
 178         }
 179
 180         spin_unlock_irqrestore(&port->lock, flags);
 181
 182         tty_flip_buffer_push(&port->state->port);
 183 }
 184
 185 static void digicolor_uart_tx(struct uart_port *port)
 186 {
 187         struct circ_buf *xmit = &port->state->xmit;
 188         unsigned long flags;
 189
 190         if (digicolor_uart_tx_full(port))
 191                 return;
 192
 193         spin_lock_irqsave(&port->lock, flags);
 194
 195         if (port->x_char) {
 196                 writeb_relaxed(port->x_char, port->membase + UA_EMI_REC);
 197                 port->icount.tx++;
 198                 port->x_char = 0;
 199                 goto out;
 200         }
 201
 202         if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
 203                 digicolor_uart_stop_tx(port);
 204                 goto out;
 205         }
 206
 207         while (!uart_circ_empty(xmit)) {
 208                 writeb(xmit->buf[xmit->tail], port->membase + UA_EMI_REC);
 209                 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 210                 port->icount.tx++;
 211
 212                 if (digicolor_uart_tx_full(port))
 213                         break;
 214         }
 215
 216         if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 217                 uart_write_wakeup(port);
 218
 219 out:
 220         spin_unlock_irqrestore(&port->lock, flags);
 221 }
 222
 223 static irqreturn_t digicolor_uart_int(int irq, void *dev_id)
 224 {
 225         struct uart_port *port = dev_id;
 226         u8 int_status = readb_relaxed(port->membase + UA_INT_STATUS);
 227
 228         writeb_relaxed(UA_INT_RX | UA_INT_TX,
 229                        port->membase + UA_INTFLAG_CLEAR);
 230
 231         if (int_status & UA_INT_RX)
 232                 digicolor_uart_rx(port);
 233         if (int_status & UA_INT_TX)
 234                 digicolor_uart_tx(port);
 235
 236         return IRQ_HANDLED;
 237 }
 238
 239 static unsigned int digicolor_uart_tx_empty(struct uart_port *port)
 240 {
 241         u8 status = readb_relaxed(port->membase + UA_STATUS);
 242
 243         return (status & UA_STATUS_TX_READY) ? TIOCSER_TEMT : 0;
 244 }
 245
 246 static unsigned int digicolor_uart_get_mctrl(struct uart_port *port)
 247 {
 248         return TIOCM_CTS;
 249 }
 250
 251 static void digicolor_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
 252 {
 253 }
 254
 255 static void digicolor_uart_break_ctl(struct uart_port *port, int state)
 256 {
 257 }
 258
 259 static int digicolor_uart_startup(struct uart_port *port)
 260 {
 261         struct digicolor_port *dp =
 262                 container_of(port, struct digicolor_port, port);
 263
 264         writeb_relaxed(UA_ENABLE_ENABLE, port->membase + UA_ENABLE);
 265         writeb_relaxed(UA_CONTROL_SOFT_RESET, port->membase + UA_CONTROL);
 266         writeb_relaxed(0, port->membase + UA_CONTROL);
 267
 268         writeb_relaxed(UA_CONFIG_FIFO_RX_FIFO_MODE
 269                        | UA_CONFIG_FIFO_TX_FIFO_MODE | UA_CONFIG_FIFO_RX_THRESH,
 270                        port->membase + UA_CONFIG_FIFO);
 271         writeb_relaxed(UA_STATUS_FIFO_RX_INT_ALMOST,
 272                        port->membase + UA_STATUS_FIFO);
 273         writeb_relaxed(UA_CONTROL_RX_ENABLE | UA_CONTROL_TX_ENABLE,
 274                        port->membase + UA_CONTROL);
 275         writeb_relaxed(UA_INT_TX | UA_INT_RX,
 276                        port->membase + UA_INT_ENABLE);
 277
 278         schedule_delayed_work(&dp->rx_poll_work, msecs_to_jiffies(100));
 279
 280         return 0;
 281 }
 282
 283 static void digicolor_uart_shutdown(struct uart_port *port)
 284 {
 285         struct digicolor_port *dp =
 286                 container_of(port, struct digicolor_port, port);
 287
 288         writeb_relaxed(0, port->membase + UA_ENABLE);
 289         cancel_delayed_work_sync(&dp->rx_poll_work);
 290 }
 291
 292 static void digicolor_uart_set_termios(struct uart_port *port,
 293                                        struct ktermios *termios,
 294                                        struct ktermios *old)
 295 {
 296         unsigned int baud, divisor;
 297         u8 config = 0;
 298         unsigned long flags;
 299
 300         /* Mask termios capabilities we don't support */
 301         termios->c_cflag &= ~CMSPAR;
 302         termios->c_iflag &= ~(BRKINT | IGNBRK);
 303
 304         /* Limit baud rates so that we don't need the fractional divider */
 305         baud = uart_get_baud_rate(port, termios, old,
 306                                   port->uartclk / (0x10000*16),
 307                                   port->uartclk / 256);
 308         divisor = uart_get_divisor(port, baud) - 1;
 309
 310         switch (termios->c_cflag & CSIZE) {
 311         case CS7:
 312                 break;
 313         case CS8:
 314         default:
 315                 config |= UA_CONFIG_CHAR_LEN;
 316                 break;
 317         }
 318
 319         if (termios->c_cflag & CSTOPB)
 320                 config |= UA_CONFIG_STOP_BITS;
 321
 322         if (termios->c_cflag & PARENB) {
 323                 config |= UA_CONFIG_PARITY;
 324                 if (termios->c_cflag & PARODD)
 325                         config |= UA_CONFIG_ODD_PARITY;
 326         }
 327
 328         /* Set read status mask */
 329         port->read_status_mask = UA_STATUS_OVERRUN_ERR;
 330         if (termios->c_iflag & INPCK)
 331                 port->read_status_mask |= UA_STATUS_PARITY_ERR
 332                         | UA_STATUS_FRAME_ERR;
 333
 334         /* Set status ignore mask */
 335         port->ignore_status_mask = 0;
 336         if (!(termios->c_cflag & CREAD))
 337                 port->ignore_status_mask |= UA_STATUS_OVERRUN_ERR
 338                         | UA_STATUS_PARITY_ERR | UA_STATUS_FRAME_ERR;
 339
 340         spin_lock_irqsave(&port->lock, flags);
 341
 342         uart_update_timeout(port, termios->c_cflag, baud);
 343
 344         writeb_relaxed(config, port->membase + UA_CONFIG);
 345         writeb_relaxed(divisor & 0xff, port->membase + UA_HBAUD_LO);
 346         writeb_relaxed(divisor >> 8, port->membase + UA_HBAUD_HI);
 347
 348         spin_unlock_irqrestore(&port->lock, flags);
 349 }
 350
 351 static const char *digicolor_uart_type(struct uart_port *port)
 352 {
 353         return (port->type == PORT_DIGICOLOR) ? "DIGICOLOR USART" : NULL;
 354 }
 355
 356 static void digicolor_uart_config_port(struct uart_port *port, int flags)
 357 {
 358         if (flags & UART_CONFIG_TYPE)
 359                 port->type = PORT_DIGICOLOR;
 360 }
 361
 362 static void digicolor_uart_release_port(struct uart_port *port)
 363 {
 364 }
 365
 366 static int digicolor_uart_request_port(struct uart_port *port)
 367 {
 368         return 0;
 369 }
 370
 371 static const struct uart_ops digicolor_uart_ops = {
 372         .tx_empty       = digicolor_uart_tx_empty,
 373         .set_mctrl      = digicolor_uart_set_mctrl,
 374         .get_mctrl      = digicolor_uart_get_mctrl,
 375         .stop_tx        = digicolor_uart_stop_tx,
 376         .start_tx       = digicolor_uart_start_tx,
 377         .stop_rx        = digicolor_uart_stop_rx,
 378         .break_ctl      = digicolor_uart_break_ctl,
 379         .startup        = digicolor_uart_startup,
 380         .shutdown       = digicolor_uart_shutdown,
 381         .set_termios    = digicolor_uart_set_termios,
 382         .type           = digicolor_uart_type,
 383         .config_port    = digicolor_uart_config_port,
 384         .release_port   = digicolor_uart_release_port,
 385         .request_port   = digicolor_uart_request_port,
 386 };
 387
 388 static void digicolor_uart_console_putchar(struct uart_port *port, int ch)
 389 {
 390         while (digicolor_uart_tx_full(port))
 391                 cpu_relax();
 392
 393         writeb_relaxed(ch, port->membase + UA_EMI_REC);
 394 }
 395
 396 static void digicolor_uart_console_write(struct console *co, const char *c,
 397                                          unsigned n)
 398 {
 399         struct uart_port *port = digicolor_ports[co->index];
 400         u8 status;
 401         unsigned long flags;
 402         int locked = 1;
 403
 404         if (oops_in_progress)
 405                 locked = spin_trylock_irqsave(&port->lock, flags);
 406         else
 407                 spin_lock_irqsave(&port->lock, flags);
 408
 409         uart_console_write(port, c, n, digicolor_uart_console_putchar);
 410
 411         if (locked)
 412                 spin_unlock_irqrestore(&port->lock, flags);
 413
 414         /* Wait for transmitter to become empty */
 415         do {
 416                 status = readb_relaxed(port->membase + UA_STATUS);
 417         } while ((status & UA_STATUS_TX_READY) == 0);
 418 }
 419
 420 static int digicolor_uart_console_setup(struct console *co, char *options)
 421 {
 422         int baud = 115200, bits = 8, parity = 'n', flow = 'n';
 423         struct uart_port *port;
 424
 425         if (co->index < 0 || co->index >= DIGICOLOR_USART_NR)
 426                 return -EINVAL;
 427
 428         port = digicolor_ports[co->index];
 429         if (!port)
 430                 return -ENODEV;
 431
 432         if (options)
 433                 uart_parse_options(options, &baud, &parity, &bits, &flow);
 434
 435         return uart_set_options(port, co, baud, parity, bits, flow);
 436 }
 437
 438 static struct console digicolor_console = {
 439         .name   = "ttyS",
 440         .device = uart_console_device,
 441         .write  = digicolor_uart_console_write,
 442         .setup  = digicolor_uart_console_setup,
 443         .flags  = CON_PRINTBUFFER,
 444         .index  = -1,
 445 };
 446
 447 static struct uart_driver digicolor_uart = {
 448         .driver_name    = "digicolor-usart",
 449         .dev_name       = "ttyS",
 450         .nr             = DIGICOLOR_USART_NR,
 451 };
 452
 453 static int digicolor_uart_probe(struct platform_device *pdev)
 454 {
 455         struct device_node *np = pdev->dev.of_node;
 456         int ret, index;
 457         struct digicolor_port *dp;
 458         struct resource *res;
 459         struct clk *uart_clk;
 460
 461         if (!np) {
 462                 dev_err(&pdev->dev, "Missing device tree node\n");
 463                 return -ENXIO;
 464         }
 465
 466         index = of_alias_get_id(np, "serial");
 467         if (index < 0 || index >= DIGICOLOR_USART_NR)
 468                 return -EINVAL;
 469
 470         dp = devm_kzalloc(&pdev->dev, sizeof(*dp), GFP_KERNEL);
 471         if (!dp)
 472                 return -ENOMEM;
 473
 474         uart_clk = devm_clk_get(&pdev->dev, NULL);
 475         if (IS_ERR(uart_clk))
 476                 return PTR_ERR(uart_clk);
 477
 478         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 479         dp->port.mapbase = res->start;
 480         dp->port.membase = devm_ioremap_resource(&pdev->dev, res);
 481         if (IS_ERR(dp->port.membase))
 482                 return PTR_ERR(dp->port.membase);
 483
 484         dp->port.irq = platform_get_irq(pdev, 0);
 485         if (IS_ERR_VALUE(dp->port.irq))
 486                 return dp->port.irq;
 487
 488         dp->port.iotype = UPIO_MEM;
 489         dp->port.uartclk = clk_get_rate(uart_clk);
 490         dp->port.fifosize = 16;
 491         dp->port.dev = &pdev->dev;
 492         dp->port.ops = &digicolor_uart_ops;
 493         dp->port.line = index;
 494         dp->port.type = PORT_DIGICOLOR;
 495         spin_lock_init(&dp->port.lock);
 496
 497         digicolor_ports[index] = &dp->port;
 498         platform_set_drvdata(pdev, &dp->port);
 499
 500         INIT_DELAYED_WORK(&dp->rx_poll_work, digicolor_rx_poll);
 501
 502         ret = devm_request_irq(&pdev->dev, dp->port.irq, digicolor_uart_int, 0,
 503                                dev_name(&pdev->dev), &dp->port);
 504         if (ret)
 505                 return ret;
 506
 507         return uart_add_one_port(&digicolor_uart, &dp->port);
 508 }
 509
 510 static int digicolor_uart_remove(struct platform_device *pdev)
 511 {
 512         struct uart_port *port = platform_get_drvdata(pdev);
 513
 514         uart_remove_one_port(&digicolor_uart, port);
 515
 516         return 0;
 517 }
 518
 519 static const struct of_device_id digicolor_uart_dt_ids[] = {
 520         { .compatible = "cnxt,cx92755-usart", },
 521         { }
 522 };
 523 MODULE_DEVICE_TABLE(of, digicolor_uart_dt_ids);
 524
 525 static struct platform_driver digicolor_uart_platform = {
 526         .driver = {
 527                 .name           = "digicolor-usart",
 528                 .of_match_table = of_match_ptr(digicolor_uart_dt_ids),
 529         },
 530         .probe  = digicolor_uart_probe,
 531         .remove = digicolor_uart_remove,
 532 };
 533
 534 static int __init digicolor_uart_init(void)
 535 {
 536         int ret;
 537
 538         if (IS_ENABLED(CONFIG_SERIAL_CONEXANT_DIGICOLOR_CONSOLE)) {
 539                 digicolor_uart.cons = &digicolor_console;
 540                 digicolor_console.data = &digicolor_uart;
 541         }
 542
 543         ret = uart_register_driver(&digicolor_uart);
 544         if (ret)
 545                 return ret;
 546
 547         return platform_driver_register(&digicolor_uart_platform);
 548 }
 549 module_init(digicolor_uart_init);
 550
 551 static void __exit digicolor_uart_exit(void)
 552 {
 553         platform_driver_unregister(&digicolor_uart_platform);
 554         uart_unregister_driver(&digicolor_uart);
 555 }
 556 module_exit(digicolor_uart_exit);
 557
 558 MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>");
 559 MODULE_DESCRIPTION("Conexant Digicolor USART serial driver");
 560 MODULE_LICENSE("GPL");