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                 termios->c_cflag &= ~CSIZE;
 317                 termios->c_cflag |= CS8;
 318                 break;
 319         }
 320
 321         if (termios->c_cflag & CSTOPB)
 322                 config |= UA_CONFIG_STOP_BITS;
 323
 324         if (termios->c_cflag & PARENB) {
 325                 config |= UA_CONFIG_PARITY;
 326                 if (termios->c_cflag & PARODD)
 327                         config |= UA_CONFIG_ODD_PARITY;
 328         }
 329
 330         /* Set read status mask */
 331         port->read_status_mask = UA_STATUS_OVERRUN_ERR;
 332         if (termios->c_iflag & INPCK)
 333                 port->read_status_mask |= UA_STATUS_PARITY_ERR
 334                         | UA_STATUS_FRAME_ERR;
 335
 336         /* Set status ignore mask */
 337         port->ignore_status_mask = 0;
 338         if (!(termios->c_cflag & CREAD))
 339                 port->ignore_status_mask |= UA_STATUS_OVERRUN_ERR
 340                         | UA_STATUS_PARITY_ERR | UA_STATUS_FRAME_ERR;
 341
 342         spin_lock_irqsave(&port->lock, flags);
 343
 344         uart_update_timeout(port, termios->c_cflag, baud);
 345
 346         writeb_relaxed(config, port->membase + UA_CONFIG);
 347         writeb_relaxed(divisor & 0xff, port->membase + UA_HBAUD_LO);
 348         writeb_relaxed(divisor >> 8, port->membase + UA_HBAUD_HI);
 349
 350         spin_unlock_irqrestore(&port->lock, flags);
 351 }
 352
 353 static const char *digicolor_uart_type(struct uart_port *port)
 354 {
 355         return (port->type == PORT_DIGICOLOR) ? "DIGICOLOR USART" : NULL;
 356 }
 357
 358 static void digicolor_uart_config_port(struct uart_port *port, int flags)
 359 {
 360         if (flags & UART_CONFIG_TYPE)
 361                 port->type = PORT_DIGICOLOR;
 362 }
 363
 364 static void digicolor_uart_release_port(struct uart_port *port)
 365 {
 366 }
 367
 368 static int digicolor_uart_request_port(struct uart_port *port)
 369 {
 370         return 0;
 371 }
 372
 373 static const struct uart_ops digicolor_uart_ops = {
 374         .tx_empty       = digicolor_uart_tx_empty,
 375         .set_mctrl      = digicolor_uart_set_mctrl,
 376         .get_mctrl      = digicolor_uart_get_mctrl,
 377         .stop_tx        = digicolor_uart_stop_tx,
 378         .start_tx       = digicolor_uart_start_tx,
 379         .stop_rx        = digicolor_uart_stop_rx,
 380         .break_ctl      = digicolor_uart_break_ctl,
 381         .startup        = digicolor_uart_startup,
 382         .shutdown       = digicolor_uart_shutdown,
 383         .set_termios    = digicolor_uart_set_termios,
 384         .type           = digicolor_uart_type,
 385         .config_port    = digicolor_uart_config_port,
 386         .release_port   = digicolor_uart_release_port,
 387         .request_port   = digicolor_uart_request_port,
 388 };
 389
 390 static void digicolor_uart_console_putchar(struct uart_port *port, int ch)
 391 {
 392         while (digicolor_uart_tx_full(port))
 393                 cpu_relax();
 394
 395         writeb_relaxed(ch, port->membase + UA_EMI_REC);
 396 }
 397
 398 static void digicolor_uart_console_write(struct console *co, const char *c,
 399                                          unsigned n)
 400 {
 401         struct uart_port *port = digicolor_ports[co->index];
 402         u8 status;
 403         unsigned long flags;
 404         int locked = 1;
 405
 406         if (oops_in_progress)
 407                 locked = spin_trylock_irqsave(&port->lock, flags);
 408         else
 409                 spin_lock_irqsave(&port->lock, flags);
 410
 411         uart_console_write(port, c, n, digicolor_uart_console_putchar);
 412
 413         if (locked)
 414                 spin_unlock_irqrestore(&port->lock, flags);
 415
 416         /* Wait for transmitter to become empty */
 417         do {
 418                 status = readb_relaxed(port->membase + UA_STATUS);
 419         } while ((status & UA_STATUS_TX_READY) == 0);
 420 }
 421
 422 static int digicolor_uart_console_setup(struct console *co, char *options)
 423 {
 424         int baud = 115200, bits = 8, parity = 'n', flow = 'n';
 425         struct uart_port *port;
 426
 427         if (co->index < 0 || co->index >= DIGICOLOR_USART_NR)
 428                 return -EINVAL;
 429
 430         port = digicolor_ports[co->index];
 431         if (!port)
 432                 return -ENODEV;
 433
 434         if (options)
 435                 uart_parse_options(options, &baud, &parity, &bits, &flow);
 436
 437         return uart_set_options(port, co, baud, parity, bits, flow);
 438 }
 439
 440 static struct console digicolor_console = {
 441         .name   = "ttyS",
 442         .device = uart_console_device,
 443         .write  = digicolor_uart_console_write,
 444         .setup  = digicolor_uart_console_setup,
 445         .flags  = CON_PRINTBUFFER,
 446         .index  = -1,
 447 };
 448
 449 static struct uart_driver digicolor_uart = {
 450         .driver_name    = "digicolor-usart",
 451         .dev_name       = "ttyS",
 452         .nr             = DIGICOLOR_USART_NR,
 453 };
 454
 455 static int digicolor_uart_probe(struct platform_device *pdev)
 456 {
 457         struct device_node *np = pdev->dev.of_node;
 458         int irq, ret, index;
 459         struct digicolor_port *dp;
 460         struct resource *res;
 461         struct clk *uart_clk;
 462
 463         if (!np) {
 464                 dev_err(&pdev->dev, "Missing device tree node\n");
 465                 return -ENXIO;
 466         }
 467
 468         index = of_alias_get_id(np, "serial");
 469         if (index < 0 || index >= DIGICOLOR_USART_NR)
 470                 return -EINVAL;
 471
 472         dp = devm_kzalloc(&pdev->dev, sizeof(*dp), GFP_KERNEL);
 473         if (!dp)
 474                 return -ENOMEM;
 475
 476         uart_clk = devm_clk_get(&pdev->dev, NULL);
 477         if (IS_ERR(uart_clk))
 478                 return PTR_ERR(uart_clk);
 479
 480         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 481         dp->port.membase = devm_ioremap_resource(&pdev->dev, res);
 482         if (IS_ERR(dp->port.membase))
 483                 return PTR_ERR(dp->port.membase);
 484         dp->port.mapbase = res->start;
 485
 486         irq = platform_get_irq(pdev, 0);
 487         if (irq < 0)
 488                 return irq;
 489         dp->port.irq = irq;
 490
 491         dp->port.iotype = UPIO_MEM;
 492         dp->port.uartclk = clk_get_rate(uart_clk);
 493         dp->port.fifosize = 16;
 494         dp->port.dev = &pdev->dev;
 495         dp->port.ops = &digicolor_uart_ops;
 496         dp->port.line = index;
 497         dp->port.type = PORT_DIGICOLOR;
 498         spin_lock_init(&dp->port.lock);
 499
 500         digicolor_ports[index] = &dp->port;
 501         platform_set_drvdata(pdev, &dp->port);
 502
 503         INIT_DELAYED_WORK(&dp->rx_poll_work, digicolor_rx_poll);
 504
 505         ret = devm_request_irq(&pdev->dev, dp->port.irq, digicolor_uart_int, 0,
 506                                dev_name(&pdev->dev), &dp->port);
 507         if (ret)
 508                 return ret;
 509
 510         return uart_add_one_port(&digicolor_uart, &dp->port);
 511 }
 512
 513 static int digicolor_uart_remove(struct platform_device *pdev)
 514 {
 515         struct uart_port *port = platform_get_drvdata(pdev);
 516
 517         uart_remove_one_port(&digicolor_uart, port);
 518
 519         return 0;
 520 }
 521
 522 static const struct of_device_id digicolor_uart_dt_ids[] = {
 523         { .compatible = "cnxt,cx92755-usart", },
 524         { }
 525 };
 526 MODULE_DEVICE_TABLE(of, digicolor_uart_dt_ids);
 527
 528 static struct platform_driver digicolor_uart_platform = {
 529         .driver = {
 530                 .name           = "digicolor-usart",
 531                 .of_match_table = of_match_ptr(digicolor_uart_dt_ids),
 532         },
 533         .probe  = digicolor_uart_probe,
 534         .remove = digicolor_uart_remove,
 535 };
 536
 537 static int __init digicolor_uart_init(void)
 538 {
 539         int ret;
 540
 541         if (IS_ENABLED(CONFIG_SERIAL_CONEXANT_DIGICOLOR_CONSOLE)) {
 542                 digicolor_uart.cons = &digicolor_console;
 543                 digicolor_console.data = &digicolor_uart;
 544         }
 545
 546         ret = uart_register_driver(&digicolor_uart);
 547         if (ret)
 548                 return ret;
 549
 550         ret = platform_driver_register(&digicolor_uart_platform);
 551         if (ret)
 552                 uart_unregister_driver(&digicolor_uart);
 553
 554         return ret;
 555 }
 556 module_init(digicolor_uart_init);
 557
 558 static void __exit digicolor_uart_exit(void)
 559 {
 560         platform_driver_unregister(&digicolor_uart_platform);
 561         uart_unregister_driver(&digicolor_uart);
 562 }
 563 module_exit(digicolor_uart_exit);
 564
 565 MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>");
 566 MODULE_DESCRIPTION("Conexant Digicolor USART serial driver");
 567 MODULE_LICENSE("GPL");