drivers/tty/serial/digicolor-usart.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  *  Driver for Conexant Digicolor serial ports (USART)
   4  *
   5  * Author: Baruch Siach <baruch@tkos.co.il>
   6  *
   7  * Copyright (C) 2014 Paradox Innovation Ltd.
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/console.h>
  12 #include <linux/serial_core.h>
  13 #include <linux/serial.h>
  14 #include <linux/clk.h>
  15 #include <linux/io.h>
  16 #include <linux/tty.h>
  17 #include <linux/tty_flip.h>
  18 #include <linux/of.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/workqueue.h>
  21
  22 #define UA_ENABLE                       0x00
  23 #define UA_ENABLE_ENABLE                BIT(0)
  24
  25 #define UA_CONTROL                      0x01
  26 #define UA_CONTROL_RX_ENABLE            BIT(0)
  27 #define UA_CONTROL_TX_ENABLE            BIT(1)
  28 #define UA_CONTROL_SOFT_RESET           BIT(2)
  29
  30 #define UA_STATUS                       0x02
  31 #define UA_STATUS_PARITY_ERR            BIT(0)
  32 #define UA_STATUS_FRAME_ERR             BIT(1)
  33 #define UA_STATUS_OVERRUN_ERR           BIT(2)
  34 #define UA_STATUS_TX_READY              BIT(6)
  35
  36 #define UA_CONFIG                       0x03
  37 #define UA_CONFIG_CHAR_LEN              BIT(0)
  38 #define UA_CONFIG_STOP_BITS             BIT(1)
  39 #define UA_CONFIG_PARITY                BIT(2)
  40 #define UA_CONFIG_ODD_PARITY            BIT(4)
  41
  42 #define UA_EMI_REC                      0x04
  43
  44 #define UA_HBAUD_LO                     0x08
  45 #define UA_HBAUD_HI                     0x09
  46
  47 #define UA_STATUS_FIFO                  0x0a
  48 #define UA_STATUS_FIFO_RX_EMPTY         BIT(2)
  49 #define UA_STATUS_FIFO_RX_INT_ALMOST    BIT(3)
  50 #define UA_STATUS_FIFO_TX_FULL          BIT(4)
  51 #define UA_STATUS_FIFO_TX_INT_ALMOST    BIT(7)
  52
  53 #define UA_CONFIG_FIFO                  0x0b
  54 #define UA_CONFIG_FIFO_RX_THRESH        7
  55 #define UA_CONFIG_FIFO_RX_FIFO_MODE     BIT(3)
  56 #define UA_CONFIG_FIFO_TX_FIFO_MODE     BIT(7)
  57
  58 #define UA_INTFLAG_CLEAR                0x1c
  59 #define UA_INTFLAG_SET                  0x1d
  60 #define UA_INT_ENABLE                   0x1e
  61 #define UA_INT_STATUS                   0x1f
  62
  63 #define UA_INT_TX                       BIT(0)
  64 #define UA_INT_RX                       BIT(1)
  65
  66 #define DIGICOLOR_USART_NR              3
  67
  68 /*
  69  * We use the 16 bytes hardware FIFO to buffer Rx traffic. Rx interrupt is
  70  * only produced when the FIFO is filled more than a certain configurable
  71  * threshold. Unfortunately, there is no way to set this threshold below half
  72  * FIFO. This means that we must periodically poll the FIFO status register to
  73  * see whether there are waiting Rx bytes.
  74  */
  75
  76 struct digicolor_port {
  77         struct uart_port port;
  78         struct delayed_work rx_poll_work;
  79 };
  80
  81 static struct uart_port *digicolor_ports[DIGICOLOR_USART_NR];
  82
  83 static bool digicolor_uart_tx_full(struct uart_port *port)
  84 {
  85         return !!(readb_relaxed(port->membase + UA_STATUS_FIFO) &
  86                   UA_STATUS_FIFO_TX_FULL);
  87 }
  88
  89 static bool digicolor_uart_rx_empty(struct uart_port *port)
  90 {
  91         return !!(readb_relaxed(port->membase + UA_STATUS_FIFO) &
  92                   UA_STATUS_FIFO_RX_EMPTY);
  93 }
  94
  95 static void digicolor_uart_stop_tx(struct uart_port *port)
  96 {
  97         u8 int_enable = readb_relaxed(port->membase + UA_INT_ENABLE);
  98
  99         int_enable &= ~UA_INT_TX;
 100         writeb_relaxed(int_enable, port->membase + UA_INT_ENABLE);
 101 }
 102
 103 static void digicolor_uart_start_tx(struct uart_port *port)
 104 {
 105         u8 int_enable = readb_relaxed(port->membase + UA_INT_ENABLE);
 106
 107         int_enable |= UA_INT_TX;
 108         writeb_relaxed(int_enable, port->membase + UA_INT_ENABLE);
 109 }
 110
 111 static void digicolor_uart_stop_rx(struct uart_port *port)
 112 {
 113         u8 int_enable = readb_relaxed(port->membase + UA_INT_ENABLE);
 114
 115         int_enable &= ~UA_INT_RX;
 116         writeb_relaxed(int_enable, port->membase + UA_INT_ENABLE);
 117 }
 118
 119 static void digicolor_rx_poll(struct work_struct *work)
 120 {
 121         struct digicolor_port *dp =
 122                 container_of(to_delayed_work(work),
 123                              struct digicolor_port, rx_poll_work);
 124
 125         if (!digicolor_uart_rx_empty(&dp->port))
 126                 /* force RX interrupt */
 127                 writeb_relaxed(UA_INT_RX, dp->port.membase + UA_INTFLAG_SET);
 128
 129         schedule_delayed_work(&dp->rx_poll_work, msecs_to_jiffies(100));
 130 }
 131
 132 static void digicolor_uart_rx(struct uart_port *port)
 133 {
 134         unsigned long flags;
 135
 136         spin_lock_irqsave(&port->lock, flags);
 137
 138         while (1) {
 139                 u8 status, ch, ch_flag;
 140
 141                 if (digicolor_uart_rx_empty(port))
 142                         break;
 143
 144                 ch = readb_relaxed(port->membase + UA_EMI_REC);
 145                 status = readb_relaxed(port->membase + UA_STATUS);
 146
 147                 port->icount.rx++;
 148                 ch_flag = TTY_NORMAL;
 149
 150                 if (status) {
 151                         if (status & UA_STATUS_PARITY_ERR)
 152                                 port->icount.parity++;
 153                         else if (status & UA_STATUS_FRAME_ERR)
 154                                 port->icount.frame++;
 155                         else if (status & UA_STATUS_OVERRUN_ERR)
 156                                 port->icount.overrun++;
 157
 158                         status &= port->read_status_mask;
 159
 160                         if (status & UA_STATUS_PARITY_ERR)
 161                                 ch_flag = TTY_PARITY;
 162                         else if (status & UA_STATUS_FRAME_ERR)
 163                                 ch_flag = TTY_FRAME;
 164                         else if (status & UA_STATUS_OVERRUN_ERR)
 165                                 ch_flag = TTY_OVERRUN;
 166                 }
 167
 168                 if (status & port->ignore_status_mask)
 169                         continue;
 170
 171                 uart_insert_char(port, status, UA_STATUS_OVERRUN_ERR, ch,
 172                                  ch_flag);
 173         }
 174
 175         spin_unlock_irqrestore(&port->lock, flags);
 176
 177         tty_flip_buffer_push(&port->state->port);
 178 }
 179
 180 static void digicolor_uart_tx(struct uart_port *port)
 181 {
 182         struct circ_buf *xmit = &port->state->xmit;
 183         unsigned long flags;
 184
 185         if (digicolor_uart_tx_full(port))
 186                 return;
 187
 188         spin_lock_irqsave(&port->lock, flags);
 189
 190         if (port->x_char) {
 191                 writeb_relaxed(port->x_char, port->membase + UA_EMI_REC);
 192                 port->icount.tx++;
 193                 port->x_char = 0;
 194                 goto out;
 195         }
 196
 197         if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
 198                 digicolor_uart_stop_tx(port);
 199                 goto out;
 200         }
 201
 202         while (!uart_circ_empty(xmit)) {
 203                 writeb(xmit->buf[xmit->tail], port->membase + UA_EMI_REC);
 204                 uart_xmit_advance(port, 1);
 205
 206                 if (digicolor_uart_tx_full(port))
 207                         break;
 208         }
 209
 210         if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 211                 uart_write_wakeup(port);
 212
 213 out:
 214         spin_unlock_irqrestore(&port->lock, flags);
 215 }
 216
 217 static irqreturn_t digicolor_uart_int(int irq, void *dev_id)
 218 {
 219         struct uart_port *port = dev_id;
 220         u8 int_status = readb_relaxed(port->membase + UA_INT_STATUS);
 221
 222         writeb_relaxed(UA_INT_RX | UA_INT_TX,
 223                        port->membase + UA_INTFLAG_CLEAR);
 224
 225         if (int_status & UA_INT_RX)
 226                 digicolor_uart_rx(port);
 227         if (int_status & UA_INT_TX)
 228                 digicolor_uart_tx(port);
 229
 230         return IRQ_HANDLED;
 231 }
 232
 233 static unsigned int digicolor_uart_tx_empty(struct uart_port *port)
 234 {
 235         u8 status = readb_relaxed(port->membase + UA_STATUS);
 236
 237         return (status & UA_STATUS_TX_READY) ? TIOCSER_TEMT : 0;
 238 }
 239
 240 static unsigned int digicolor_uart_get_mctrl(struct uart_port *port)
 241 {
 242         return TIOCM_CTS;
 243 }
 244
 245 static void digicolor_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
 246 {
 247 }
 248
 249 static void digicolor_uart_break_ctl(struct uart_port *port, int state)
 250 {
 251 }
 252
 253 static int digicolor_uart_startup(struct uart_port *port)
 254 {
 255         struct digicolor_port *dp =
 256                 container_of(port, struct digicolor_port, port);
 257
 258         writeb_relaxed(UA_ENABLE_ENABLE, port->membase + UA_ENABLE);
 259         writeb_relaxed(UA_CONTROL_SOFT_RESET, port->membase + UA_CONTROL);
 260         writeb_relaxed(0, port->membase + UA_CONTROL);
 261
 262         writeb_relaxed(UA_CONFIG_FIFO_RX_FIFO_MODE
 263                        | UA_CONFIG_FIFO_TX_FIFO_MODE | UA_CONFIG_FIFO_RX_THRESH,
 264                        port->membase + UA_CONFIG_FIFO);
 265         writeb_relaxed(UA_STATUS_FIFO_RX_INT_ALMOST,
 266                        port->membase + UA_STATUS_FIFO);
 267         writeb_relaxed(UA_CONTROL_RX_ENABLE | UA_CONTROL_TX_ENABLE,
 268                        port->membase + UA_CONTROL);
 269         writeb_relaxed(UA_INT_TX | UA_INT_RX,
 270                        port->membase + UA_INT_ENABLE);
 271
 272         schedule_delayed_work(&dp->rx_poll_work, msecs_to_jiffies(100));
 273
 274         return 0;
 275 }
 276
 277 static void digicolor_uart_shutdown(struct uart_port *port)
 278 {
 279         struct digicolor_port *dp =
 280                 container_of(port, struct digicolor_port, port);
 281
 282         writeb_relaxed(0, port->membase + UA_ENABLE);
 283         cancel_delayed_work_sync(&dp->rx_poll_work);
 284 }
 285
 286 static void digicolor_uart_set_termios(struct uart_port *port,
 287                                        struct ktermios *termios,
 288                                        const struct ktermios *old)
 289 {
 290         unsigned int baud, divisor;
 291         u8 config = 0;
 292         unsigned long flags;
 293
 294         /* Mask termios capabilities we don't support */
 295         termios->c_cflag &= ~CMSPAR;
 296         termios->c_iflag &= ~(BRKINT | IGNBRK);
 297
 298         /* Limit baud rates so that we don't need the fractional divider */
 299         baud = uart_get_baud_rate(port, termios, old,
 300                                   port->uartclk / (0x10000*16),
 301                                   port->uartclk / 256);
 302         divisor = uart_get_divisor(port, baud) - 1;
 303
 304         switch (termios->c_cflag & CSIZE) {
 305         case CS7:
 306                 break;
 307         case CS8:
 308         default:
 309                 config |= UA_CONFIG_CHAR_LEN;
 310                 termios->c_cflag &= ~CSIZE;
 311                 termios->c_cflag |= CS8;
 312                 break;
 313         }
 314
 315         if (termios->c_cflag & CSTOPB)
 316                 config |= UA_CONFIG_STOP_BITS;
 317
 318         if (termios->c_cflag & PARENB) {
 319                 config |= UA_CONFIG_PARITY;
 320                 if (termios->c_cflag & PARODD)
 321                         config |= UA_CONFIG_ODD_PARITY;
 322         }
 323
 324         /* Set read status mask */
 325         port->read_status_mask = UA_STATUS_OVERRUN_ERR;
 326         if (termios->c_iflag & INPCK)
 327                 port->read_status_mask |= UA_STATUS_PARITY_ERR
 328                         | UA_STATUS_FRAME_ERR;
 329
 330         /* Set status ignore mask */
 331         port->ignore_status_mask = 0;
 332         if (!(termios->c_cflag & CREAD))
 333                 port->ignore_status_mask |= UA_STATUS_OVERRUN_ERR
 334                         | UA_STATUS_PARITY_ERR | UA_STATUS_FRAME_ERR;
 335
 336         spin_lock_irqsave(&port->lock, flags);
 337
 338         uart_update_timeout(port, termios->c_cflag, baud);
 339
 340         writeb_relaxed(config, port->membase + UA_CONFIG);
 341         writeb_relaxed(divisor & 0xff, port->membase + UA_HBAUD_LO);
 342         writeb_relaxed(divisor >> 8, port->membase + UA_HBAUD_HI);
 343
 344         spin_unlock_irqrestore(&port->lock, flags);
 345 }
 346
 347 static const char *digicolor_uart_type(struct uart_port *port)
 348 {
 349         return (port->type == PORT_DIGICOLOR) ? "DIGICOLOR USART" : NULL;
 350 }
 351
 352 static void digicolor_uart_config_port(struct uart_port *port, int flags)
 353 {
 354         if (flags & UART_CONFIG_TYPE)
 355                 port->type = PORT_DIGICOLOR;
 356 }
 357
 358 static void digicolor_uart_release_port(struct uart_port *port)
 359 {
 360 }
 361
 362 static int digicolor_uart_request_port(struct uart_port *port)
 363 {
 364         return 0;
 365 }
 366
 367 static const struct uart_ops digicolor_uart_ops = {
 368         .tx_empty       = digicolor_uart_tx_empty,
 369         .set_mctrl      = digicolor_uart_set_mctrl,
 370         .get_mctrl      = digicolor_uart_get_mctrl,
 371         .stop_tx        = digicolor_uart_stop_tx,
 372         .start_tx       = digicolor_uart_start_tx,
 373         .stop_rx        = digicolor_uart_stop_rx,
 374         .break_ctl      = digicolor_uart_break_ctl,
 375         .startup        = digicolor_uart_startup,
 376         .shutdown       = digicolor_uart_shutdown,
 377         .set_termios    = digicolor_uart_set_termios,
 378         .type           = digicolor_uart_type,
 379         .config_port    = digicolor_uart_config_port,
 380         .release_port   = digicolor_uart_release_port,
 381         .request_port   = digicolor_uart_request_port,
 382 };
 383
 384 static void digicolor_uart_console_putchar(struct uart_port *port, unsigned char ch)
 385 {
 386         while (digicolor_uart_tx_full(port))
 387                 cpu_relax();
 388
 389         writeb_relaxed(ch, port->membase + UA_EMI_REC);
 390 }
 391
 392 static void digicolor_uart_console_write(struct console *co, const char *c,
 393                                          unsigned n)
 394 {
 395         struct uart_port *port = digicolor_ports[co->index];
 396         u8 status;
 397         unsigned long flags;
 398         int locked = 1;
 399
 400         if (oops_in_progress)
 401                 locked = spin_trylock_irqsave(&port->lock, flags);
 402         else
 403                 spin_lock_irqsave(&port->lock, flags);
 404
 405         uart_console_write(port, c, n, digicolor_uart_console_putchar);
 406
 407         if (locked)
 408                 spin_unlock_irqrestore(&port->lock, flags);
 409
 410         /* Wait for transmitter to become empty */
 411         do {
 412                 status = readb_relaxed(port->membase + UA_STATUS);
 413         } while ((status & UA_STATUS_TX_READY) == 0);
 414 }
 415
 416 static int digicolor_uart_console_setup(struct console *co, char *options)
 417 {
 418         int baud = 115200, bits = 8, parity = 'n', flow = 'n';
 419         struct uart_port *port;
 420
 421         if (co->index < 0 || co->index >= DIGICOLOR_USART_NR)
 422                 return -EINVAL;
 423
 424         port = digicolor_ports[co->index];
 425         if (!port)
 426                 return -ENODEV;
 427
 428         if (options)
 429                 uart_parse_options(options, &baud, &parity, &bits, &flow);
 430
 431         return uart_set_options(port, co, baud, parity, bits, flow);
 432 }
 433
 434 static struct console digicolor_console = {
 435         .name   = "ttyS",
 436         .device = uart_console_device,
 437         .write  = digicolor_uart_console_write,
 438         .setup  = digicolor_uart_console_setup,
 439         .flags  = CON_PRINTBUFFER,
 440         .index  = -1,
 441 };
 442
 443 static struct uart_driver digicolor_uart = {
 444         .driver_name    = "digicolor-usart",
 445         .dev_name       = "ttyS",
 446         .nr             = DIGICOLOR_USART_NR,
 447 };
 448
 449 static int digicolor_uart_probe(struct platform_device *pdev)
 450 {
 451         struct device_node *np = pdev->dev.of_node;
 452         int irq, ret, index;
 453         struct digicolor_port *dp;
 454         struct resource *res;
 455         struct clk *uart_clk;
 456
 457         if (!np) {
 458                 dev_err(&pdev->dev, "Missing device tree node\n");
 459                 return -ENXIO;
 460         }
 461
 462         index = of_alias_get_id(np, "serial");
 463         if (index < 0 || index >= DIGICOLOR_USART_NR)
 464                 return -EINVAL;
 465
 466         dp = devm_kzalloc(&pdev->dev, sizeof(*dp), GFP_KERNEL);
 467         if (!dp)
 468                 return -ENOMEM;
 469
 470         uart_clk = devm_clk_get(&pdev->dev, NULL);
 471         if (IS_ERR(uart_clk))
 472                 return PTR_ERR(uart_clk);
 473
 474         dp->port.membase = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
 475         if (IS_ERR(dp->port.membase))
 476                 return PTR_ERR(dp->port.membase);
 477         dp->port.mapbase = res->start;
 478
 479         irq = platform_get_irq(pdev, 0);
 480         if (irq < 0)
 481                 return irq;
 482         dp->port.irq = irq;
 483
 484         dp->port.iotype = UPIO_MEM;
 485         dp->port.uartclk = clk_get_rate(uart_clk);
 486         dp->port.fifosize = 16;
 487         dp->port.dev = &pdev->dev;
 488         dp->port.ops = &digicolor_uart_ops;
 489         dp->port.line = index;
 490         dp->port.type = PORT_DIGICOLOR;
 491         spin_lock_init(&dp->port.lock);
 492
 493         digicolor_ports[index] = &dp->port;
 494         platform_set_drvdata(pdev, &dp->port);
 495
 496         INIT_DELAYED_WORK(&dp->rx_poll_work, digicolor_rx_poll);
 497
 498         ret = devm_request_irq(&pdev->dev, dp->port.irq, digicolor_uart_int, 0,
 499                                dev_name(&pdev->dev), &dp->port);
 500         if (ret)
 501                 return ret;
 502
 503         return uart_add_one_port(&digicolor_uart, &dp->port);
 504 }
 505
 506 static int digicolor_uart_remove(struct platform_device *pdev)
 507 {
 508         struct uart_port *port = platform_get_drvdata(pdev);
 509
 510         uart_remove_one_port(&digicolor_uart, port);
 511
 512         return 0;
 513 }
 514
 515 static const struct of_device_id digicolor_uart_dt_ids[] = {
 516         { .compatible = "cnxt,cx92755-usart", },
 517         { }
 518 };
 519 MODULE_DEVICE_TABLE(of, digicolor_uart_dt_ids);
 520
 521 static struct platform_driver digicolor_uart_platform = {
 522         .driver = {
 523                 .name           = "digicolor-usart",
 524                 .of_match_table = of_match_ptr(digicolor_uart_dt_ids),
 525         },
 526         .probe  = digicolor_uart_probe,
 527         .remove = digicolor_uart_remove,
 528 };
 529
 530 static int __init digicolor_uart_init(void)
 531 {
 532         int ret;
 533
 534         if (IS_ENABLED(CONFIG_SERIAL_CONEXANT_DIGICOLOR_CONSOLE)) {
 535                 digicolor_uart.cons = &digicolor_console;
 536                 digicolor_console.data = &digicolor_uart;
 537         }
 538
 539         ret = uart_register_driver(&digicolor_uart);
 540         if (ret)
 541                 return ret;
 542
 543         ret = platform_driver_register(&digicolor_uart_platform);
 544         if (ret)
 545                 uart_unregister_driver(&digicolor_uart);
 546
 547         return ret;
 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");