drivers/serial/uartlite.c

   1 /*
   2  * uartlite.c: Serial driver for Xilinx uartlite serial controller
   3  *
   4  * Peter Korsgaard <jacmet@sunsite.dk>
   5  *
   6  * This file is licensed under the terms of the GNU General Public License
   7  * version 2.  This program is licensed "as is" without any warranty of any
   8  * kind, whether express or implied.
   9  */
  10
  11 #include <linux/platform_device.h>
  12 #include <linux/module.h>
  13 #include <linux/console.h>
  14 #include <linux/serial.h>
  15 #include <linux/serial_core.h>
  16 #include <linux/tty.h>
  17 #include <linux/delay.h>
  18 #include <linux/interrupt.h>
  19 #include <asm/io.h>
  20
  21 #define ULITE_MAJOR             204
  22 #define ULITE_MINOR             187
  23 #define ULITE_NR_UARTS          4
  24
  25 /* For register details see datasheet:
  26    http://www.xilinx.com/bvdocs/ipcenter/data_sheet/opb_uartlite.pdf
  27 */
  28 #define ULITE_RX                0x00
  29 #define ULITE_TX                0x04
  30 #define ULITE_STATUS            0x08
  31 #define ULITE_CONTROL           0x0c
  32
  33 #define ULITE_REGION            16
  34
  35 #define ULITE_STATUS_RXVALID    0x01
  36 #define ULITE_STATUS_RXFULL     0x02
  37 #define ULITE_STATUS_TXEMPTY    0x04
  38 #define ULITE_STATUS_TXFULL     0x08
  39 #define ULITE_STATUS_IE         0x10
  40 #define ULITE_STATUS_OVERRUN    0x20
  41 #define ULITE_STATUS_FRAME      0x40
  42 #define ULITE_STATUS_PARITY     0x80
  43
  44 #define ULITE_CONTROL_RST_TX    0x01
  45 #define ULITE_CONTROL_RST_RX    0x02
  46 #define ULITE_CONTROL_IE        0x10
  47
  48
  49 static struct uart_port ports[ULITE_NR_UARTS];
  50
  51 static int ulite_receive(struct uart_port *port, int stat)
  52 {
  53         struct tty_struct *tty = port->info->tty;
  54         unsigned char ch = 0;
  55         char flag = TTY_NORMAL;
  56
  57         if ((stat & (ULITE_STATUS_RXVALID | ULITE_STATUS_OVERRUN
  58                      | ULITE_STATUS_FRAME)) == 0)
  59                 return 0;
  60
  61         /* stats */
  62         if (stat & ULITE_STATUS_RXVALID) {
  63                 port->icount.rx++;
  64                 ch = readb(port->membase + ULITE_RX);
  65
  66                 if (stat & ULITE_STATUS_PARITY)
  67                         port->icount.parity++;
  68         }
  69
  70         if (stat & ULITE_STATUS_OVERRUN)
  71                 port->icount.overrun++;
  72
  73         if (stat & ULITE_STATUS_FRAME)
  74                 port->icount.frame++;
  75
  76
  77         /* drop byte with parity error if IGNPAR specificed */
  78         if (stat & port->ignore_status_mask & ULITE_STATUS_PARITY)
  79                 stat &= ~ULITE_STATUS_RXVALID;
  80
  81         stat &= port->read_status_mask;
  82
  83         if (stat & ULITE_STATUS_PARITY)
  84                 flag = TTY_PARITY;
  85
  86
  87         stat &= ~port->ignore_status_mask;
  88
  89         if (stat & ULITE_STATUS_RXVALID)
  90                 tty_insert_flip_char(tty, ch, flag);
  91
  92         if (stat & ULITE_STATUS_FRAME)
  93                 tty_insert_flip_char(tty, 0, TTY_FRAME);
  94
  95         if (stat & ULITE_STATUS_OVERRUN)
  96                 tty_insert_flip_char(tty, 0, TTY_OVERRUN);
  97
  98         return 1;
  99 }
 100
 101 static int ulite_transmit(struct uart_port *port, int stat)
 102 {
 103         struct circ_buf *xmit  = &port->info->xmit;
 104
 105         if (stat & ULITE_STATUS_TXFULL)
 106                 return 0;
 107
 108         if (port->x_char) {
 109                 writeb(port->x_char, port->membase + ULITE_TX);
 110                 port->x_char = 0;
 111                 port->icount.tx++;
 112                 return 1;
 113         }
 114
 115         if (uart_circ_empty(xmit) || uart_tx_stopped(port))
 116                 return 0;
 117
 118         writeb(xmit->buf[xmit->tail], port->membase + ULITE_TX);
 119         xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE-1);
 120         port->icount.tx++;
 121
 122         /* wake up */
 123         if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 124                 uart_write_wakeup(port);
 125
 126         return 1;
 127 }
 128
 129 static irqreturn_t ulite_isr(int irq, void *dev_id)
 130 {
 131         struct uart_port *port = (struct uart_port *)dev_id;
 132         int busy;
 133
 134         do {
 135                 int stat = readb(port->membase + ULITE_STATUS);
 136                 busy  = ulite_receive(port, stat);
 137                 busy |= ulite_transmit(port, stat);
 138         } while (busy);
 139
 140         tty_flip_buffer_push(port->info->tty);
 141
 142         return IRQ_HANDLED;
 143 }
 144
 145 static unsigned int ulite_tx_empty(struct uart_port *port)
 146 {
 147         unsigned long flags;
 148         unsigned int ret;
 149
 150         spin_lock_irqsave(&port->lock, flags);
 151         ret = readb(port->membase + ULITE_STATUS);
 152         spin_unlock_irqrestore(&port->lock, flags);
 153
 154         return ret & ULITE_STATUS_TXEMPTY ? TIOCSER_TEMT : 0;
 155 }
 156
 157 static unsigned int ulite_get_mctrl(struct uart_port *port)
 158 {
 159         return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
 160 }
 161
 162 static void ulite_set_mctrl(struct uart_port *port, unsigned int mctrl)
 163 {
 164         /* N/A */
 165 }
 166
 167 static void ulite_stop_tx(struct uart_port *port)
 168 {
 169         /* N/A */
 170 }
 171
 172 static void ulite_start_tx(struct uart_port *port)
 173 {
 174         ulite_transmit(port, readb(port->membase + ULITE_STATUS));
 175 }
 176
 177 static void ulite_stop_rx(struct uart_port *port)
 178 {
 179         /* don't forward any more data (like !CREAD) */
 180         port->ignore_status_mask = ULITE_STATUS_RXVALID | ULITE_STATUS_PARITY
 181                 | ULITE_STATUS_FRAME | ULITE_STATUS_OVERRUN;
 182 }
 183
 184 static void ulite_enable_ms(struct uart_port *port)
 185 {
 186         /* N/A */
 187 }
 188
 189 static void ulite_break_ctl(struct uart_port *port, int ctl)
 190 {
 191         /* N/A */
 192 }
 193
 194 static int ulite_startup(struct uart_port *port)
 195 {
 196         int ret;
 197
 198         ret = request_irq(port->irq, ulite_isr,
 199                           IRQF_DISABLED | IRQF_SAMPLE_RANDOM, "uartlite", port);
 200         if (ret)
 201                 return ret;
 202
 203         writeb(ULITE_CONTROL_RST_RX | ULITE_CONTROL_RST_TX,
 204                port->membase + ULITE_CONTROL);
 205         writeb(ULITE_CONTROL_IE, port->membase + ULITE_CONTROL);
 206
 207         return 0;
 208 }
 209
 210 static void ulite_shutdown(struct uart_port *port)
 211 {
 212         writeb(0, port->membase + ULITE_CONTROL);
 213         readb(port->membase + ULITE_CONTROL); /* dummy */
 214         free_irq(port->irq, port);
 215 }
 216
 217 static void ulite_set_termios(struct uart_port *port, struct ktermios *termios,
 218                               struct ktermios *old)
 219 {
 220         unsigned long flags;
 221         unsigned int baud;
 222
 223         spin_lock_irqsave(&port->lock, flags);
 224
 225         port->read_status_mask = ULITE_STATUS_RXVALID | ULITE_STATUS_OVERRUN
 226                 | ULITE_STATUS_TXFULL;
 227
 228         if (termios->c_iflag & INPCK)
 229                 port->read_status_mask |=
 230                         ULITE_STATUS_PARITY | ULITE_STATUS_FRAME;
 231
 232         port->ignore_status_mask = 0;
 233         if (termios->c_iflag & IGNPAR)
 234                 port->ignore_status_mask |= ULITE_STATUS_PARITY
 235                         | ULITE_STATUS_FRAME | ULITE_STATUS_OVERRUN;
 236
 237         /* ignore all characters if CREAD is not set */
 238         if ((termios->c_cflag & CREAD) == 0)
 239                 port->ignore_status_mask |=
 240                         ULITE_STATUS_RXVALID | ULITE_STATUS_PARITY
 241                         | ULITE_STATUS_FRAME | ULITE_STATUS_OVERRUN;
 242
 243         /* update timeout */
 244         baud = uart_get_baud_rate(port, termios, old, 0, 460800);
 245         uart_update_timeout(port, termios->c_cflag, baud);
 246
 247         spin_unlock_irqrestore(&port->lock, flags);
 248 }
 249
 250 static const char *ulite_type(struct uart_port *port)
 251 {
 252         return port->type == PORT_UARTLITE ? "uartlite" : NULL;
 253 }
 254
 255 static void ulite_release_port(struct uart_port *port)
 256 {
 257         release_mem_region(port->mapbase, ULITE_REGION);
 258         iounmap(port->membase);
 259         port->membase = NULL;
 260 }
 261
 262 static int ulite_request_port(struct uart_port *port)
 263 {
 264         if (!request_mem_region(port->mapbase, ULITE_REGION, "uartlite")) {
 265                 dev_err(port->dev, "Memory region busy\n");
 266                 return -EBUSY;
 267         }
 268
 269         port->membase = ioremap(port->mapbase, ULITE_REGION);
 270         if (!port->membase) {
 271                 dev_err(port->dev, "Unable to map registers\n");
 272                 release_mem_region(port->mapbase, ULITE_REGION);
 273                 return -EBUSY;
 274         }
 275
 276         return 0;
 277 }
 278
 279 static void ulite_config_port(struct uart_port *port, int flags)
 280 {
 281         if (!ulite_request_port(port))
 282                 port->type = PORT_UARTLITE;
 283 }
 284
 285 static int ulite_verify_port(struct uart_port *port, struct serial_struct *ser)
 286 {
 287         /* we don't want the core code to modify any port params */
 288         return -EINVAL;
 289 }
 290
 291 static struct uart_ops ulite_ops = {
 292         .tx_empty       = ulite_tx_empty,
 293         .set_mctrl      = ulite_set_mctrl,
 294         .get_mctrl      = ulite_get_mctrl,
 295         .stop_tx        = ulite_stop_tx,
 296         .start_tx       = ulite_start_tx,
 297         .stop_rx        = ulite_stop_rx,
 298         .enable_ms      = ulite_enable_ms,
 299         .break_ctl      = ulite_break_ctl,
 300         .startup        = ulite_startup,
 301         .shutdown       = ulite_shutdown,
 302         .set_termios    = ulite_set_termios,
 303         .type           = ulite_type,
 304         .release_port   = ulite_release_port,
 305         .request_port   = ulite_request_port,
 306         .config_port    = ulite_config_port,
 307         .verify_port    = ulite_verify_port
 308 };
 309
 310 #ifdef CONFIG_SERIAL_UARTLITE_CONSOLE
 311 static void ulite_console_wait_tx(struct uart_port *port)
 312 {
 313         int i;
 314
 315         /* wait up to 10ms for the character(s) to be sent */
 316         for (i = 0; i < 10000; i++) {
 317                 if (readb(port->membase + ULITE_STATUS) & ULITE_STATUS_TXEMPTY)
 318                         break;
 319                 udelay(1);
 320         }
 321 }
 322
 323 static void ulite_console_putchar(struct uart_port *port, int ch)
 324 {
 325         ulite_console_wait_tx(port);
 326         writeb(ch, port->membase + ULITE_TX);
 327 }
 328
 329 static void ulite_console_write(struct console *co, const char *s,
 330                                 unsigned int count)
 331 {
 332         struct uart_port *port = &ports[co->index];
 333         unsigned long flags;
 334         unsigned int ier;
 335         int locked = 1;
 336
 337         if (oops_in_progress) {
 338                 locked = spin_trylock_irqsave(&port->lock, flags);
 339         } else
 340                 spin_lock_irqsave(&port->lock, flags);
 341
 342         /* save and disable interrupt */
 343         ier = readb(port->membase + ULITE_STATUS) & ULITE_STATUS_IE;
 344         writeb(0, port->membase + ULITE_CONTROL);
 345
 346         uart_console_write(port, s, count, ulite_console_putchar);
 347
 348         ulite_console_wait_tx(port);
 349
 350         /* restore interrupt state */
 351         if (ier)
 352                 writeb(ULITE_CONTROL_IE, port->membase + ULITE_CONTROL);
 353
 354         if (locked)
 355                 spin_unlock_irqrestore(&port->lock, flags);
 356 }
 357
 358 static int __init ulite_console_setup(struct console *co, char *options)
 359 {
 360         struct uart_port *port;
 361         int baud = 9600;
 362         int bits = 8;
 363         int parity = 'n';
 364         int flow = 'n';
 365
 366         if (co->index < 0 || co->index >= ULITE_NR_UARTS)
 367                 return -EINVAL;
 368
 369         port = &ports[co->index];
 370
 371         /* not initialized yet? */
 372         if (!port->membase)
 373                 return -ENODEV;
 374
 375         if (options)
 376                 uart_parse_options(options, &baud, &parity, &bits, &flow);
 377
 378         return uart_set_options(port, co, baud, parity, bits, flow);
 379 }
 380
 381 static struct uart_driver ulite_uart_driver;
 382
 383 static struct console ulite_console = {
 384         .name   = "ttyUL",
 385         .write  = ulite_console_write,
 386         .device = uart_console_device,
 387         .setup  = ulite_console_setup,
 388         .flags  = CON_PRINTBUFFER,
 389         .index  = -1, /* Specified on the cmdline (e.g. console=ttyUL0 ) */
 390         .data   = &ulite_uart_driver,
 391 };
 392
 393 static int __init ulite_console_init(void)
 394 {
 395         register_console(&ulite_console);
 396         return 0;
 397 }
 398
 399 console_initcall(ulite_console_init);
 400
 401 #endif /* CONFIG_SERIAL_UARTLITE_CONSOLE */
 402
 403 static struct uart_driver ulite_uart_driver = {
 404         .owner          = THIS_MODULE,
 405         .driver_name    = "uartlite",
 406         .dev_name       = "ttyUL",
 407         .major          = ULITE_MAJOR,
 408         .minor          = ULITE_MINOR,
 409         .nr             = ULITE_NR_UARTS,
 410 #ifdef CONFIG_SERIAL_UARTLITE_CONSOLE
 411         .cons           = &ulite_console,
 412 #endif
 413 };
 414
 415 static int __devinit ulite_probe(struct platform_device *pdev)
 416 {
 417         struct resource *res, *res2;
 418         struct uart_port *port;
 419
 420         if (pdev->id < 0 || pdev->id >= ULITE_NR_UARTS)
 421                 return -EINVAL;
 422
 423         if (ports[pdev->id].membase)
 424                 return -EBUSY;
 425
 426         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 427         if (!res)
 428                 return -ENODEV;
 429
 430         res2 = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 431         if (!res2)
 432                 return -ENODEV;
 433
 434         port = &ports[pdev->id];
 435
 436         port->fifosize  = 16;
 437         port->regshift  = 2;
 438         port->iotype    = UPIO_MEM;
 439         port->iobase    = 1; /* mark port in use */
 440         port->mapbase   = res->start;
 441         port->membase   = NULL;
 442         port->ops       = &ulite_ops;
 443         port->irq       = res2->start;
 444         port->flags     = UPF_BOOT_AUTOCONF;
 445         port->dev       = &pdev->dev;
 446         port->type      = PORT_UNKNOWN;
 447         port->line      = pdev->id;
 448
 449         uart_add_one_port(&ulite_uart_driver, port);
 450         platform_set_drvdata(pdev, port);
 451
 452         return 0;
 453 }
 454
 455 static int ulite_remove(struct platform_device *pdev)
 456 {
 457         struct uart_port *port = platform_get_drvdata(pdev);
 458
 459         platform_set_drvdata(pdev, NULL);
 460
 461         if (port)
 462                 uart_remove_one_port(&ulite_uart_driver, port);
 463
 464         /* mark port as free */
 465         port->membase = NULL;
 466
 467         return 0;
 468 }
 469
 470 static struct platform_driver ulite_platform_driver = {
 471         .probe  = ulite_probe,
 472         .remove = ulite_remove,
 473         .driver = {
 474                    .owner = THIS_MODULE,
 475                    .name  = "uartlite",
 476                    },
 477 };
 478
 479 int __init ulite_init(void)
 480 {
 481         int ret;
 482
 483         ret = uart_register_driver(&ulite_uart_driver);
 484         if (ret)
 485                 return ret;
 486
 487         ret = platform_driver_register(&ulite_platform_driver);
 488         if (ret)
 489                 uart_unregister_driver(&ulite_uart_driver);
 490
 491         return ret;
 492 }
 493
 494 void __exit ulite_exit(void)
 495 {
 496         platform_driver_unregister(&ulite_platform_driver);
 497         uart_unregister_driver(&ulite_uart_driver);
 498 }
 499
 500 module_init(ulite_init);
 501 module_exit(ulite_exit);
 502
 503 MODULE_AUTHOR("Peter Korsgaard <jacmet@sunsite.dk>");
 504 MODULE_DESCRIPTION("Xilinx uartlite serial driver");
 505 MODULE_LICENSE("GPL");