drivers/tty/serial/vt8500_serial.c

   1 /*
   2  * Copyright (C) 2010 Alexey Charkov <alchark@gmail.com>
   3  *
   4  * Based on msm_serial.c, which is:
   5  * Copyright (C) 2007 Google, Inc.
   6  * Author: Robert Love <rlove@google.com>
   7  *
   8  * This software is licensed under the terms of the GNU General Public
   9  * License version 2, as published by the Free Software Foundation, and
  10  * may be copied, distributed, and modified under those terms.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  */
  17
  18 #if defined(CONFIG_SERIAL_VT8500_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
  19 # define SUPPORT_SYSRQ
  20 #endif
  21
  22 #include <linux/hrtimer.h>
  23 #include <linux/delay.h>
  24 #include <linux/module.h>
  25 #include <linux/io.h>
  26 #include <linux/ioport.h>
  27 #include <linux/irq.h>
  28 #include <linux/init.h>
  29 #include <linux/console.h>
  30 #include <linux/tty.h>
  31 #include <linux/tty_flip.h>
  32 #include <linux/serial_core.h>
  33 #include <linux/serial.h>
  34 #include <linux/slab.h>
  35 #include <linux/clk.h>
  36 #include <linux/platform_device.h>
  37
  38 /*
  39  * UART Register offsets
  40  */
  41
  42 #define VT8500_URTDR            0x0000  /* Transmit data */
  43 #define VT8500_URRDR            0x0004  /* Receive data */
  44 #define VT8500_URDIV            0x0008  /* Clock/Baud rate divisor */
  45 #define VT8500_URLCR            0x000C  /* Line control */
  46 #define VT8500_URICR            0x0010  /* IrDA control */
  47 #define VT8500_URIER            0x0014  /* Interrupt enable */
  48 #define VT8500_URISR            0x0018  /* Interrupt status */
  49 #define VT8500_URUSR            0x001c  /* UART status */
  50 #define VT8500_URFCR            0x0020  /* FIFO control */
  51 #define VT8500_URFIDX           0x0024  /* FIFO index */
  52 #define VT8500_URBKR            0x0028  /* Break signal count */
  53 #define VT8500_URTOD            0x002c  /* Time out divisor */
  54 #define VT8500_TXFIFO           0x1000  /* Transmit FIFO (16x8) */
  55 #define VT8500_RXFIFO           0x1020  /* Receive FIFO (16x10) */
  56
  57 /*
  58  * Interrupt enable and status bits
  59  */
  60
  61 #define TXDE    (1 << 0)        /* Tx Data empty */
  62 #define RXDF    (1 << 1)        /* Rx Data full */
  63 #define TXFAE   (1 << 2)        /* Tx FIFO almost empty */
  64 #define TXFE    (1 << 3)        /* Tx FIFO empty */
  65 #define RXFAF   (1 << 4)        /* Rx FIFO almost full */
  66 #define RXFF    (1 << 5)        /* Rx FIFO full */
  67 #define TXUDR   (1 << 6)        /* Tx underrun */
  68 #define RXOVER  (1 << 7)        /* Rx overrun */
  69 #define PER     (1 << 8)        /* Parity error */
  70 #define FER     (1 << 9)        /* Frame error */
  71 #define TCTS    (1 << 10)       /* Toggle of CTS */
  72 #define RXTOUT  (1 << 11)       /* Rx timeout */
  73 #define BKDONE  (1 << 12)       /* Break signal done */
  74 #define ERR     (1 << 13)       /* AHB error response */
  75
  76 #define RX_FIFO_INTS    (RXFAF | RXFF | RXOVER | PER | FER | RXTOUT)
  77 #define TX_FIFO_INTS    (TXFAE | TXFE | TXUDR)
  78
  79 struct vt8500_port {
  80         struct uart_port        uart;
  81         char                    name[16];
  82         struct clk              *clk;
  83         unsigned int            ier;
  84 };
  85
  86 static inline void vt8500_write(struct uart_port *port, unsigned int val,
  87                              unsigned int off)
  88 {
  89         writel(val, port->membase + off);
  90 }
  91
  92 static inline unsigned int vt8500_read(struct uart_port *port, unsigned int off)
  93 {
  94         return readl(port->membase + off);
  95 }
  96
  97 static void vt8500_stop_tx(struct uart_port *port)
  98 {
  99         struct vt8500_port *vt8500_port = container_of(port,
 100                                                        struct vt8500_port,
 101                                                        uart);
 102
 103         vt8500_port->ier &= ~TX_FIFO_INTS;
 104         vt8500_write(port, vt8500_port->ier, VT8500_URIER);
 105 }
 106
 107 static void vt8500_stop_rx(struct uart_port *port)
 108 {
 109         struct vt8500_port *vt8500_port = container_of(port,
 110                                                        struct vt8500_port,
 111                                                        uart);
 112
 113         vt8500_port->ier &= ~RX_FIFO_INTS;
 114         vt8500_write(port, vt8500_port->ier, VT8500_URIER);
 115 }
 116
 117 static void vt8500_enable_ms(struct uart_port *port)
 118 {
 119         struct vt8500_port *vt8500_port = container_of(port,
 120                                                        struct vt8500_port,
 121                                                        uart);
 122
 123         vt8500_port->ier |= TCTS;
 124         vt8500_write(port, vt8500_port->ier, VT8500_URIER);
 125 }
 126
 127 static void handle_rx(struct uart_port *port)
 128 {
 129         struct tty_struct *tty = tty_port_tty_get(&port->state->port);
 130         if (!tty) {
 131                 /* Discard data: no tty available */
 132                 int count = (vt8500_read(port, VT8500_URFIDX) & 0x1f00) >> 8;
 133                 u16 ch;
 134                 while (count--)
 135                         ch = readw(port->membase + VT8500_RXFIFO);
 136                 return;
 137         }
 138
 139         /*
 140          * Handle overrun
 141          */
 142         if ((vt8500_read(port, VT8500_URISR) & RXOVER)) {
 143                 port->icount.overrun++;
 144                 tty_insert_flip_char(tty, 0, TTY_OVERRUN);
 145         }
 146
 147         /* and now the main RX loop */
 148         while (vt8500_read(port, VT8500_URFIDX) & 0x1f00) {
 149                 unsigned int c;
 150                 char flag = TTY_NORMAL;
 151
 152                 c = readw(port->membase + VT8500_RXFIFO) & 0x3ff;
 153
 154                 /* Mask conditions we're ignorning. */
 155                 c &= ~port->read_status_mask;
 156
 157                 if (c & FER) {
 158                         port->icount.frame++;
 159                         flag = TTY_FRAME;
 160                 } else if (c & PER) {
 161                         port->icount.parity++;
 162                         flag = TTY_PARITY;
 163                 }
 164                 port->icount.rx++;
 165
 166                 if (!uart_handle_sysrq_char(port, c))
 167                         tty_insert_flip_char(tty, c, flag);
 168         }
 169
 170         tty_flip_buffer_push(tty);
 171         tty_kref_put(tty);
 172 }
 173
 174 static void handle_tx(struct uart_port *port)
 175 {
 176         struct circ_buf *xmit = &port->state->xmit;
 177
 178         if (port->x_char) {
 179                 writeb(port->x_char, port->membase + VT8500_TXFIFO);
 180                 port->icount.tx++;
 181                 port->x_char = 0;
 182         }
 183         if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
 184                 vt8500_stop_tx(port);
 185                 return;
 186         }
 187
 188         while ((vt8500_read(port, VT8500_URFIDX) & 0x1f) < 16) {
 189                 if (uart_circ_empty(xmit))
 190                         break;
 191
 192                 writeb(xmit->buf[xmit->tail], port->membase + VT8500_TXFIFO);
 193
 194                 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 195                 port->icount.tx++;
 196         }
 197
 198         if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 199                 uart_write_wakeup(port);
 200
 201         if (uart_circ_empty(xmit))
 202                 vt8500_stop_tx(port);
 203 }
 204
 205 static void vt8500_start_tx(struct uart_port *port)
 206 {
 207         struct vt8500_port *vt8500_port = container_of(port,
 208                                                        struct vt8500_port,
 209                                                        uart);
 210
 211         vt8500_port->ier &= ~TX_FIFO_INTS;
 212         vt8500_write(port, vt8500_port->ier, VT8500_URIER);
 213         handle_tx(port);
 214         vt8500_port->ier |= TX_FIFO_INTS;
 215         vt8500_write(port, vt8500_port->ier, VT8500_URIER);
 216 }
 217
 218 static void handle_delta_cts(struct uart_port *port)
 219 {
 220         port->icount.cts++;
 221         wake_up_interruptible(&port->state->port.delta_msr_wait);
 222 }
 223
 224 static irqreturn_t vt8500_irq(int irq, void *dev_id)
 225 {
 226         struct uart_port *port = dev_id;
 227         unsigned long isr;
 228
 229         spin_lock(&port->lock);
 230         isr = vt8500_read(port, VT8500_URISR);
 231
 232         /* Acknowledge active status bits */
 233         vt8500_write(port, isr, VT8500_URISR);
 234
 235         if (isr & RX_FIFO_INTS)
 236                 handle_rx(port);
 237         if (isr & TX_FIFO_INTS)
 238                 handle_tx(port);
 239         if (isr & TCTS)
 240                 handle_delta_cts(port);
 241
 242         spin_unlock(&port->lock);
 243
 244         return IRQ_HANDLED;
 245 }
 246
 247 static unsigned int vt8500_tx_empty(struct uart_port *port)
 248 {
 249         return (vt8500_read(port, VT8500_URFIDX) & 0x1f) < 16 ?
 250                                                 TIOCSER_TEMT : 0;
 251 }
 252
 253 static unsigned int vt8500_get_mctrl(struct uart_port *port)
 254 {
 255         unsigned int usr;
 256
 257         usr = vt8500_read(port, VT8500_URUSR);
 258         if (usr & (1 << 4))
 259                 return TIOCM_CTS;
 260         else
 261                 return 0;
 262 }
 263
 264 static void vt8500_set_mctrl(struct uart_port *port, unsigned int mctrl)
 265 {
 266 }
 267
 268 static void vt8500_break_ctl(struct uart_port *port, int break_ctl)
 269 {
 270         if (break_ctl)
 271                 vt8500_write(port, vt8500_read(port, VT8500_URLCR) | (1 << 9),
 272                              VT8500_URLCR);
 273 }
 274
 275 static int vt8500_set_baud_rate(struct uart_port *port, unsigned int baud)
 276 {
 277         unsigned long div;
 278         unsigned int loops = 1000;
 279
 280         div = vt8500_read(port, VT8500_URDIV) & ~(0x3ff);
 281
 282         if (unlikely((baud < 900) || (baud > 921600)))
 283                 div |= 7;
 284         else
 285                 div |= (921600 / baud) - 1;
 286
 287         while ((vt8500_read(port, VT8500_URUSR) & (1 << 5)) && --loops)
 288                 cpu_relax();
 289         vt8500_write(port, div, VT8500_URDIV);
 290
 291         return baud;
 292 }
 293
 294 static int vt8500_startup(struct uart_port *port)
 295 {
 296         struct vt8500_port *vt8500_port =
 297                         container_of(port, struct vt8500_port, uart);
 298         int ret;
 299
 300         snprintf(vt8500_port->name, sizeof(vt8500_port->name),
 301                  "vt8500_serial%d", port->line);
 302
 303         ret = request_irq(port->irq, vt8500_irq, IRQF_TRIGGER_HIGH,
 304                           vt8500_port->name, port);
 305         if (unlikely(ret))
 306                 return ret;
 307
 308         vt8500_write(port, 0x03, VT8500_URLCR); /* enable TX & RX */
 309
 310         return 0;
 311 }
 312
 313 static void vt8500_shutdown(struct uart_port *port)
 314 {
 315         struct vt8500_port *vt8500_port =
 316                         container_of(port, struct vt8500_port, uart);
 317
 318         vt8500_port->ier = 0;
 319
 320         /* disable interrupts and FIFOs */
 321         vt8500_write(&vt8500_port->uart, 0, VT8500_URIER);
 322         vt8500_write(&vt8500_port->uart, 0x880, VT8500_URFCR);
 323         free_irq(port->irq, port);
 324 }
 325
 326 static void vt8500_set_termios(struct uart_port *port,
 327                                struct ktermios *termios,
 328                                struct ktermios *old)
 329 {
 330         struct vt8500_port *vt8500_port =
 331                         container_of(port, struct vt8500_port, uart);
 332         unsigned long flags;
 333         unsigned int baud, lcr;
 334         unsigned int loops = 1000;
 335
 336         spin_lock_irqsave(&port->lock, flags);
 337
 338         /* calculate and set baud rate */
 339         baud = uart_get_baud_rate(port, termios, old, 900, 921600);
 340         baud = vt8500_set_baud_rate(port, baud);
 341         if (tty_termios_baud_rate(termios))
 342                 tty_termios_encode_baud_rate(termios, baud, baud);
 343
 344         /* calculate parity */
 345         lcr = vt8500_read(&vt8500_port->uart, VT8500_URLCR);
 346         lcr &= ~((1 << 5) | (1 << 4));
 347         if (termios->c_cflag & PARENB) {
 348                 lcr |= (1 << 4);
 349                 termios->c_cflag &= ~CMSPAR;
 350                 if (termios->c_cflag & PARODD)
 351                         lcr |= (1 << 5);
 352         }
 353
 354         /* calculate bits per char */
 355         lcr &= ~(1 << 2);
 356         switch (termios->c_cflag & CSIZE) {
 357         case CS7:
 358                 break;
 359         case CS8:
 360         default:
 361                 lcr |= (1 << 2);
 362                 termios->c_cflag &= ~CSIZE;
 363                 termios->c_cflag |= CS8;
 364                 break;
 365         }
 366
 367         /* calculate stop bits */
 368         lcr &= ~(1 << 3);
 369         if (termios->c_cflag & CSTOPB)
 370                 lcr |= (1 << 3);
 371
 372         /* set parity, bits per char, and stop bit */
 373         vt8500_write(&vt8500_port->uart, lcr, VT8500_URLCR);
 374
 375         /* Configure status bits to ignore based on termio flags. */
 376         port->read_status_mask = 0;
 377         if (termios->c_iflag & IGNPAR)
 378                 port->read_status_mask = FER | PER;
 379
 380         uart_update_timeout(port, termios->c_cflag, baud);
 381
 382         /* Reset FIFOs */
 383         vt8500_write(&vt8500_port->uart, 0x88c, VT8500_URFCR);
 384         while ((vt8500_read(&vt8500_port->uart, VT8500_URFCR) & 0xc)
 385                                                         && --loops)
 386                 cpu_relax();
 387
 388         /* Every possible FIFO-related interrupt */
 389         vt8500_port->ier = RX_FIFO_INTS | TX_FIFO_INTS;
 390
 391         /*
 392          * CTS flow control
 393          */
 394         if (UART_ENABLE_MS(&vt8500_port->uart, termios->c_cflag))
 395                 vt8500_port->ier |= TCTS;
 396
 397         vt8500_write(&vt8500_port->uart, 0x881, VT8500_URFCR);
 398         vt8500_write(&vt8500_port->uart, vt8500_port->ier, VT8500_URIER);
 399
 400         spin_unlock_irqrestore(&port->lock, flags);
 401 }
 402
 403 static const char *vt8500_type(struct uart_port *port)
 404 {
 405         struct vt8500_port *vt8500_port =
 406                         container_of(port, struct vt8500_port, uart);
 407         return vt8500_port->name;
 408 }
 409
 410 static void vt8500_release_port(struct uart_port *port)
 411 {
 412 }
 413
 414 static int vt8500_request_port(struct uart_port *port)
 415 {
 416         return 0;
 417 }
 418
 419 static void vt8500_config_port(struct uart_port *port, int flags)
 420 {
 421         port->type = PORT_VT8500;
 422 }
 423
 424 static int vt8500_verify_port(struct uart_port *port,
 425                               struct serial_struct *ser)
 426 {
 427         if (unlikely(ser->type != PORT_UNKNOWN && ser->type != PORT_VT8500))
 428                 return -EINVAL;
 429         if (unlikely(port->irq != ser->irq))
 430                 return -EINVAL;
 431         return 0;
 432 }
 433
 434 static struct vt8500_port *vt8500_uart_ports[4];
 435 static struct uart_driver vt8500_uart_driver;
 436
 437 #ifdef CONFIG_SERIAL_VT8500_CONSOLE
 438
 439 static inline void wait_for_xmitr(struct uart_port *port)
 440 {
 441         unsigned int status, tmout = 10000;
 442
 443         /* Wait up to 10ms for the character(s) to be sent. */
 444         do {
 445                 status = vt8500_read(port, VT8500_URFIDX);
 446
 447                 if (--tmout == 0)
 448                         break;
 449                 udelay(1);
 450         } while (status & 0x10);
 451 }
 452
 453 static void vt8500_console_putchar(struct uart_port *port, int c)
 454 {
 455         wait_for_xmitr(port);
 456         writeb(c, port->membase + VT8500_TXFIFO);
 457 }
 458
 459 static void vt8500_console_write(struct console *co, const char *s,
 460                               unsigned int count)
 461 {
 462         struct vt8500_port *vt8500_port = vt8500_uart_ports[co->index];
 463         unsigned long ier;
 464
 465         BUG_ON(co->index < 0 || co->index >= vt8500_uart_driver.nr);
 466
 467         ier = vt8500_read(&vt8500_port->uart, VT8500_URIER);
 468         vt8500_write(&vt8500_port->uart, VT8500_URIER, 0);
 469
 470         uart_console_write(&vt8500_port->uart, s, count,
 471                            vt8500_console_putchar);
 472
 473         /*
 474          *      Finally, wait for transmitter to become empty
 475          *      and switch back to FIFO
 476          */
 477         wait_for_xmitr(&vt8500_port->uart);
 478         vt8500_write(&vt8500_port->uart, VT8500_URIER, ier);
 479 }
 480
 481 static int __init vt8500_console_setup(struct console *co, char *options)
 482 {
 483         struct vt8500_port *vt8500_port;
 484         int baud = 9600;
 485         int bits = 8;
 486         int parity = 'n';
 487         int flow = 'n';
 488
 489         if (unlikely(co->index >= vt8500_uart_driver.nr || co->index < 0))
 490                 return -ENXIO;
 491
 492         vt8500_port = vt8500_uart_ports[co->index];
 493
 494         if (!vt8500_port)
 495                 return -ENODEV;
 496
 497         if (options)
 498                 uart_parse_options(options, &baud, &parity, &bits, &flow);
 499
 500         return uart_set_options(&vt8500_port->uart,
 501                                  co, baud, parity, bits, flow);
 502 }
 503
 504 static struct console vt8500_console = {
 505         .name = "ttyWMT",
 506         .write = vt8500_console_write,
 507         .device = uart_console_device,
 508         .setup = vt8500_console_setup,
 509         .flags = CON_PRINTBUFFER,
 510         .index = -1,
 511         .data = &vt8500_uart_driver,
 512 };
 513
 514 #define VT8500_CONSOLE  (&vt8500_console)
 515
 516 #else
 517 #define VT8500_CONSOLE  NULL
 518 #endif
 519
 520 static struct uart_ops vt8500_uart_pops = {
 521         .tx_empty       = vt8500_tx_empty,
 522         .set_mctrl      = vt8500_set_mctrl,
 523         .get_mctrl      = vt8500_get_mctrl,
 524         .stop_tx        = vt8500_stop_tx,
 525         .start_tx       = vt8500_start_tx,
 526         .stop_rx        = vt8500_stop_rx,
 527         .enable_ms      = vt8500_enable_ms,
 528         .break_ctl      = vt8500_break_ctl,
 529         .startup        = vt8500_startup,
 530         .shutdown       = vt8500_shutdown,
 531         .set_termios    = vt8500_set_termios,
 532         .type           = vt8500_type,
 533         .release_port   = vt8500_release_port,
 534         .request_port   = vt8500_request_port,
 535         .config_port    = vt8500_config_port,
 536         .verify_port    = vt8500_verify_port,
 537 };
 538
 539 static struct uart_driver vt8500_uart_driver = {
 540         .owner          = THIS_MODULE,
 541         .driver_name    = "vt8500_serial",
 542         .dev_name       = "ttyWMT",
 543         .nr             = 6,
 544         .cons           = VT8500_CONSOLE,
 545 };
 546
 547 static int __init vt8500_serial_probe(struct platform_device *pdev)
 548 {
 549         struct vt8500_port *vt8500_port;
 550         struct resource *mmres, *irqres;
 551         int ret;
 552
 553         mmres = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 554         irqres = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 555         if (!mmres || !irqres)
 556                 return -ENODEV;
 557
 558         vt8500_port = kzalloc(sizeof(struct vt8500_port), GFP_KERNEL);
 559         if (!vt8500_port)
 560                 return -ENOMEM;
 561
 562         vt8500_port->uart.type = PORT_VT8500;
 563         vt8500_port->uart.iotype = UPIO_MEM;
 564         vt8500_port->uart.mapbase = mmres->start;
 565         vt8500_port->uart.irq = irqres->start;
 566         vt8500_port->uart.fifosize = 16;
 567         vt8500_port->uart.ops = &vt8500_uart_pops;
 568         vt8500_port->uart.line = pdev->id;
 569         vt8500_port->uart.dev = &pdev->dev;
 570         vt8500_port->uart.flags = UPF_IOREMAP | UPF_BOOT_AUTOCONF;
 571         vt8500_port->uart.uartclk = 24000000;
 572
 573         snprintf(vt8500_port->name, sizeof(vt8500_port->name),
 574                  "VT8500 UART%d", pdev->id);
 575
 576         vt8500_port->uart.membase = ioremap(mmres->start, resource_size(mmres));
 577         if (!vt8500_port->uart.membase) {
 578                 ret = -ENOMEM;
 579                 goto err;
 580         }
 581
 582         vt8500_uart_ports[pdev->id] = vt8500_port;
 583
 584         uart_add_one_port(&vt8500_uart_driver, &vt8500_port->uart);
 585
 586         platform_set_drvdata(pdev, vt8500_port);
 587
 588         return 0;
 589
 590 err:
 591         kfree(vt8500_port);
 592         return ret;
 593 }
 594
 595 static int __devexit vt8500_serial_remove(struct platform_device *pdev)
 596 {
 597         struct vt8500_port *vt8500_port = platform_get_drvdata(pdev);
 598
 599         platform_set_drvdata(pdev, NULL);
 600         uart_remove_one_port(&vt8500_uart_driver, &vt8500_port->uart);
 601         kfree(vt8500_port);
 602
 603         return 0;
 604 }
 605
 606 static struct platform_driver vt8500_platform_driver = {
 607         .probe  = vt8500_serial_probe,
 608         .remove = vt8500_serial_remove,
 609         .driver = {
 610                 .name = "vt8500_serial",
 611                 .owner = THIS_MODULE,
 612         },
 613 };
 614
 615 static int __init vt8500_serial_init(void)
 616 {
 617         int ret;
 618
 619         ret = uart_register_driver(&vt8500_uart_driver);
 620         if (unlikely(ret))
 621                 return ret;
 622
 623         ret = platform_driver_register(&vt8500_platform_driver);
 624
 625         if (unlikely(ret))
 626                 uart_unregister_driver(&vt8500_uart_driver);
 627
 628         return ret;
 629 }
 630
 631 static void __exit vt8500_serial_exit(void)
 632 {
 633 #ifdef CONFIG_SERIAL_VT8500_CONSOLE
 634         unregister_console(&vt8500_console);
 635 #endif
 636         platform_driver_unregister(&vt8500_platform_driver);
 637         uart_unregister_driver(&vt8500_uart_driver);
 638 }
 639
 640 module_init(vt8500_serial_init);
 641 module_exit(vt8500_serial_exit);
 642
 643 MODULE_AUTHOR("Alexey Charkov <alchark@gmail.com>");
 644 MODULE_DESCRIPTION("Driver for vt8500 serial device");
 645 MODULE_LICENSE("GPL");