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_NAME              "ttyUL"
  22 #define ULITE_MAJOR             204
  23 #define ULITE_MINOR             187
  24 #define ULITE_NR_UARTS          4
  25
  26 /* For register details see datasheet:
  27    http://www.xilinx.com/bvdocs/ipcenter/data_sheet/opb_uartlite.pdf
  28 */
  29 #define ULITE_RX                0x00
  30 #define ULITE_TX                0x04
  31 #define ULITE_STATUS            0x08
  32 #define ULITE_CONTROL           0x0c
  33
  34 #define ULITE_REGION            16
  35
  36 #define ULITE_STATUS_RXVALID    0x01
  37 #define ULITE_STATUS_RXFULL     0x02
  38 #define ULITE_STATUS_TXEMPTY    0x04
  39 #define ULITE_STATUS_TXFULL     0x08
  40 #define ULITE_STATUS_IE         0x10
  41 #define ULITE_STATUS_OVERRUN    0x20
  42 #define ULITE_STATUS_FRAME      0x40
  43 #define ULITE_STATUS_PARITY     0x80
  44
  45 #define ULITE_CONTROL_RST_TX    0x01
  46 #define ULITE_CONTROL_RST_RX    0x02
  47 #define ULITE_CONTROL_IE        0x10
  48
  49
  50 static struct uart_port ulite_ports[ULITE_NR_UARTS];
  51
  52 static int ulite_receive(struct uart_port *port, int stat)
  53 {
  54         struct tty_struct *tty = port->info->tty;
  55         unsigned char ch = 0;
  56         char flag = TTY_NORMAL;
  57
  58         if ((stat & (ULITE_STATUS_RXVALID | ULITE_STATUS_OVERRUN
  59                      | ULITE_STATUS_FRAME)) == 0)
  60                 return 0;
  61
  62         /* stats */
  63         if (stat & ULITE_STATUS_RXVALID) {
  64                 port->icount.rx++;
  65                 ch = in_be32((void*)port->membase + ULITE_RX);
  66
  67                 if (stat & ULITE_STATUS_PARITY)
  68                         port->icount.parity++;
  69         }
  70
  71         if (stat & ULITE_STATUS_OVERRUN)
  72                 port->icount.overrun++;
  73
  74         if (stat & ULITE_STATUS_FRAME)
  75                 port->icount.frame++;
  76
  77
  78         /* drop byte with parity error if IGNPAR specificed */
  79         if (stat & port->ignore_status_mask & ULITE_STATUS_PARITY)
  80                 stat &= ~ULITE_STATUS_RXVALID;
  81
  82         stat &= port->read_status_mask;
  83
  84         if (stat & ULITE_STATUS_PARITY)
  85                 flag = TTY_PARITY;
  86
  87
  88         stat &= ~port->ignore_status_mask;
  89
  90         if (stat & ULITE_STATUS_RXVALID)
  91                 tty_insert_flip_char(tty, ch, flag);
  92
  93         if (stat & ULITE_STATUS_FRAME)
  94                 tty_insert_flip_char(tty, 0, TTY_FRAME);
  95
  96         if (stat & ULITE_STATUS_OVERRUN)
  97                 tty_insert_flip_char(tty, 0, TTY_OVERRUN);
  98
  99         return 1;
 100 }
 101
 102 static int ulite_transmit(struct uart_port *port, int stat)
 103 {
 104         struct circ_buf *xmit  = &port->info->xmit;
 105
 106         if (stat & ULITE_STATUS_TXFULL)
 107                 return 0;
 108
 109         if (port->x_char) {
 110                 out_be32((void*)port->membase + ULITE_TX, port->x_char);
 111                 port->x_char = 0;
 112                 port->icount.tx++;
 113                 return 1;
 114         }
 115
 116         if (uart_circ_empty(xmit) || uart_tx_stopped(port))
 117                 return 0;
 118
 119         out_be32((void*)port->membase + ULITE_TX, xmit->buf[xmit->tail]);
 120         xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE-1);
 121         port->icount.tx++;
 122
 123         /* wake up */
 124         if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 125                 uart_write_wakeup(port);
 126
 127         return 1;
 128 }
 129
 130 static irqreturn_t ulite_isr(int irq, void *dev_id)
 131 {
 132         struct uart_port *port = (struct uart_port *)dev_id;
 133         int busy;
 134
 135         do {
 136                 int stat = in_be32((void*)port->membase + ULITE_STATUS);
 137                 busy  = ulite_receive(port, stat);
 138                 busy |= ulite_transmit(port, stat);
 139         } while (busy);
 140
 141         tty_flip_buffer_push(port->info->tty);
 142
 143         return IRQ_HANDLED;
 144 }
 145
 146 static unsigned int ulite_tx_empty(struct uart_port *port)
 147 {
 148         unsigned long flags;
 149         unsigned int ret;
 150
 151         spin_lock_irqsave(&port->lock, flags);
 152         ret = in_be32((void*)port->membase + ULITE_STATUS);
 153         spin_unlock_irqrestore(&port->lock, flags);
 154
 155         return ret & ULITE_STATUS_TXEMPTY ? TIOCSER_TEMT : 0;
 156 }
 157
 158 static unsigned int ulite_get_mctrl(struct uart_port *port)
 159 {
 160         return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
 161 }
 162
 163 static void ulite_set_mctrl(struct uart_port *port, unsigned int mctrl)
 164 {
 165         /* N/A */
 166 }
 167
 168 static void ulite_stop_tx(struct uart_port *port)
 169 {
 170         /* N/A */
 171 }
 172
 173 static void ulite_start_tx(struct uart_port *port)
 174 {
 175         ulite_transmit(port, in_be32((void*)port->membase + ULITE_STATUS));
 176 }
 177
 178 static void ulite_stop_rx(struct uart_port *port)
 179 {
 180         /* don't forward any more data (like !CREAD) */
 181         port->ignore_status_mask = ULITE_STATUS_RXVALID | ULITE_STATUS_PARITY
 182                 | ULITE_STATUS_FRAME | ULITE_STATUS_OVERRUN;
 183 }
 184
 185 static void ulite_enable_ms(struct uart_port *port)
 186 {
 187         /* N/A */
 188 }
 189
 190 static void ulite_break_ctl(struct uart_port *port, int ctl)
 191 {
 192         /* N/A */
 193 }
 194
 195 static int ulite_startup(struct uart_port *port)
 196 {
 197         int ret;
 198
 199         ret = request_irq(port->irq, ulite_isr,
 200                           IRQF_DISABLED | IRQF_SAMPLE_RANDOM, "uartlite", port);
 201         if (ret)
 202                 return ret;
 203
 204         out_be32((void*)port->membase + ULITE_CONTROL,
 205                  ULITE_CONTROL_RST_RX | ULITE_CONTROL_RST_TX);
 206         out_be32((void*)port->membase + ULITE_CONTROL, ULITE_CONTROL_IE);
 207
 208         return 0;
 209 }
 210
 211 static void ulite_shutdown(struct uart_port *port)
 212 {
 213         out_be32((void*)port->membase + ULITE_CONTROL, 0);
 214         in_be32((void*)port->membase + ULITE_CONTROL); /* dummy */
 215         free_irq(port->irq, port);
 216 }
 217
 218 static void ulite_set_termios(struct uart_port *port, struct ktermios *termios,
 219                               struct ktermios *old)
 220 {
 221         unsigned long flags;
 222         unsigned int baud;
 223
 224         spin_lock_irqsave(&port->lock, flags);
 225
 226         port->read_status_mask = ULITE_STATUS_RXVALID | ULITE_STATUS_OVERRUN
 227                 | ULITE_STATUS_TXFULL;
 228
 229         if (termios->c_iflag & INPCK)
 230                 port->read_status_mask |=
 231                         ULITE_STATUS_PARITY | ULITE_STATUS_FRAME;
 232
 233         port->ignore_status_mask = 0;
 234         if (termios->c_iflag & IGNPAR)
 235                 port->ignore_status_mask |= ULITE_STATUS_PARITY
 236                         | ULITE_STATUS_FRAME | ULITE_STATUS_OVERRUN;
 237
 238         /* ignore all characters if CREAD is not set */
 239         if ((termios->c_cflag & CREAD) == 0)
 240                 port->ignore_status_mask |=
 241                         ULITE_STATUS_RXVALID | ULITE_STATUS_PARITY
 242                         | ULITE_STATUS_FRAME | ULITE_STATUS_OVERRUN;
 243
 244         /* update timeout */
 245         baud = uart_get_baud_rate(port, termios, old, 0, 460800);
 246         uart_update_timeout(port, termios->c_cflag, baud);
 247
 248         spin_unlock_irqrestore(&port->lock, flags);
 249 }
 250
 251 static const char *ulite_type(struct uart_port *port)
 252 {
 253         return port->type == PORT_UARTLITE ? "uartlite" : NULL;
 254 }
 255
 256 static void ulite_release_port(struct uart_port *port)
 257 {
 258         release_mem_region(port->mapbase, ULITE_REGION);
 259         iounmap(port->membase);
 260         port->membase = NULL;
 261 }
 262
 263 static int ulite_request_port(struct uart_port *port)
 264 {
 265         if (!request_mem_region(port->mapbase, ULITE_REGION, "uartlite")) {
 266                 dev_err(port->dev, "Memory region busy\n");
 267                 return -EBUSY;
 268         }
 269
 270         port->membase = ioremap(port->mapbase, ULITE_REGION);
 271         if (!port->membase) {
 272                 dev_err(port->dev, "Unable to map registers\n");
 273                 release_mem_region(port->mapbase, ULITE_REGION);
 274                 return -EBUSY;
 275         }
 276
 277         return 0;
 278 }
 279
 280 static void ulite_config_port(struct uart_port *port, int flags)
 281 {
 282         if (!ulite_request_port(port))
 283                 port->type = PORT_UARTLITE;
 284 }
 285
 286 static int ulite_verify_port(struct uart_port *port, struct serial_struct *ser)
 287 {
 288         /* we don't want the core code to modify any port params */
 289         return -EINVAL;
 290 }
 291
 292 static struct uart_ops ulite_ops = {
 293         .tx_empty       = ulite_tx_empty,
 294         .set_mctrl      = ulite_set_mctrl,
 295         .get_mctrl      = ulite_get_mctrl,
 296         .stop_tx        = ulite_stop_tx,
 297         .start_tx       = ulite_start_tx,
 298         .stop_rx        = ulite_stop_rx,
 299         .enable_ms      = ulite_enable_ms,
 300         .break_ctl      = ulite_break_ctl,
 301         .startup        = ulite_startup,
 302         .shutdown       = ulite_shutdown,
 303         .set_termios    = ulite_set_termios,
 304         .type           = ulite_type,
 305         .release_port   = ulite_release_port,
 306         .request_port   = ulite_request_port,
 307         .config_port    = ulite_config_port,
 308         .verify_port    = ulite_verify_port
 309 };
 310
 311 #ifdef CONFIG_SERIAL_UARTLITE_CONSOLE
 312 static void ulite_console_wait_tx(struct uart_port *port)
 313 {
 314         int i;
 315
 316         /* wait up to 10ms for the character(s) to be sent */
 317         for (i = 0; i < 10000; i++) {
 318                 if (in_be32((void*)port->membase + ULITE_STATUS) & ULITE_STATUS_TXEMPTY)
 319                         break;
 320                 udelay(1);
 321         }
 322 }
 323
 324 static void ulite_console_putchar(struct uart_port *port, int ch)
 325 {
 326         ulite_console_wait_tx(port);
 327         out_be32((void*)port->membase + ULITE_TX, ch);
 328 }
 329
 330 static void ulite_console_write(struct console *co, const char *s,
 331                                 unsigned int count)
 332 {
 333         struct uart_port *port = &ulite_ports[co->index];
 334         unsigned long flags;
 335         unsigned int ier;
 336         int locked = 1;
 337
 338         if (oops_in_progress) {
 339                 locked = spin_trylock_irqsave(&port->lock, flags);
 340         } else
 341                 spin_lock_irqsave(&port->lock, flags);
 342
 343         /* save and disable interrupt */
 344         ier = in_be32((void*)port->membase + ULITE_STATUS) & ULITE_STATUS_IE;
 345         out_be32((void*)port->membase + ULITE_CONTROL, 0);
 346
 347         uart_console_write(port, s, count, ulite_console_putchar);
 348
 349         ulite_console_wait_tx(port);
 350
 351         /* restore interrupt state */
 352         if (ier)
 353                 out_be32((void*)port->membase + ULITE_CONTROL, ULITE_CONTROL_IE);
 354
 355         if (locked)
 356                 spin_unlock_irqrestore(&port->lock, flags);
 357 }
 358
 359 static int __init ulite_console_setup(struct console *co, char *options)
 360 {
 361         struct uart_port *port;
 362         int baud = 9600;
 363         int bits = 8;
 364         int parity = 'n';
 365         int flow = 'n';
 366
 367         if (co->index < 0 || co->index >= ULITE_NR_UARTS)
 368                 return -EINVAL;
 369
 370         port = &ulite_ports[co->index];
 371
 372         /* not initialized yet? */
 373         if (!port->membase)
 374                 return -ENODEV;
 375
 376         if (options)
 377                 uart_parse_options(options, &baud, &parity, &bits, &flow);
 378
 379         return uart_set_options(port, co, baud, parity, bits, flow);
 380 }
 381
 382 static struct uart_driver ulite_uart_driver;
 383
 384 static struct console ulite_console = {
 385         .name   = ULITE_NAME,
 386         .write  = ulite_console_write,
 387         .device = uart_console_device,
 388         .setup  = ulite_console_setup,
 389         .flags  = CON_PRINTBUFFER,
 390         .index  = -1, /* Specified on the cmdline (e.g. console=ttyUL0 ) */
 391         .data   = &ulite_uart_driver,
 392 };
 393
 394 static int __init ulite_console_init(void)
 395 {
 396         register_console(&ulite_console);
 397         return 0;
 398 }
 399
 400 console_initcall(ulite_console_init);
 401
 402 #endif /* CONFIG_SERIAL_UARTLITE_CONSOLE */
 403
 404 static struct uart_driver ulite_uart_driver = {
 405         .owner          = THIS_MODULE,
 406         .driver_name    = "uartlite",
 407         .dev_name       = ULITE_NAME,
 408         .major          = ULITE_MAJOR,
 409         .minor          = ULITE_MINOR,
 410         .nr             = ULITE_NR_UARTS,
 411 #ifdef CONFIG_SERIAL_UARTLITE_CONSOLE
 412         .cons           = &ulite_console,
 413 #endif
 414 };
 415
 416 static int __devinit ulite_probe(struct platform_device *pdev)
 417 {
 418         struct resource *res, *res2;
 419         struct uart_port *port;
 420
 421         if (pdev->id < 0 || pdev->id >= ULITE_NR_UARTS)
 422                 return -EINVAL;
 423
 424         if (ulite_ports[pdev->id].membase)
 425                 return -EBUSY;
 426
 427         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 428         if (!res)
 429                 return -ENODEV;
 430
 431         res2 = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 432         if (!res2)
 433                 return -ENODEV;
 434
 435         port = &ulite_ports[pdev->id];
 436
 437         port->fifosize  = 16;
 438         port->regshift  = 2;
 439         port->iotype    = UPIO_MEM;
 440         port->iobase    = 1; /* mark port in use */
 441         port->mapbase   = res->start;
 442         port->membase   = NULL;
 443         port->ops       = &ulite_ops;
 444         port->irq       = res2->start;
 445         port->flags     = UPF_BOOT_AUTOCONF;
 446         port->dev       = &pdev->dev;
 447         port->type      = PORT_UNKNOWN;
 448         port->line      = pdev->id;
 449
 450         uart_add_one_port(&ulite_uart_driver, port);
 451         platform_set_drvdata(pdev, port);
 452
 453         return 0;
 454 }
 455
 456 static int ulite_remove(struct platform_device *pdev)
 457 {
 458         struct uart_port *port = platform_get_drvdata(pdev);
 459
 460         platform_set_drvdata(pdev, NULL);
 461
 462         if (port)
 463                 uart_remove_one_port(&ulite_uart_driver, port);
 464
 465         /* mark port as free */
 466         port->membase = NULL;
 467
 468         return 0;
 469 }
 470
 471 static struct platform_driver ulite_platform_driver = {
 472         .probe  = ulite_probe,
 473         .remove = ulite_remove,
 474         .driver = {
 475                    .owner = THIS_MODULE,
 476                    .name  = "uartlite",
 477                    },
 478 };
 479
 480 int __init ulite_init(void)
 481 {
 482         int ret;
 483
 484         ret = uart_register_driver(&ulite_uart_driver);
 485         if (ret)
 486                 return ret;
 487
 488         ret = platform_driver_register(&ulite_platform_driver);
 489         if (ret)
 490                 uart_unregister_driver(&ulite_uart_driver);
 491
 492         return ret;
 493 }
 494
 495 void __exit ulite_exit(void)
 496 {
 497         platform_driver_unregister(&ulite_platform_driver);
 498         uart_unregister_driver(&ulite_uart_driver);
 499 }
 500
 501 module_init(ulite_init);
 502 module_exit(ulite_exit);
 503
 504 MODULE_AUTHOR("Peter Korsgaard <jacmet@sunsite.dk>");
 505 MODULE_DESCRIPTION("Xilinx uartlite serial driver");
 506 MODULE_LICENSE("GPL");