drivers/serial/altera_uart.c

   1 /*
   2  * altera_uart.c -- Altera UART driver
   3  *
   4  * Based on mcf.c -- Freescale ColdFire UART driver
   5  *
   6  * (C) Copyright 2003-2007, Greg Ungerer <gerg@snapgear.com>
   7  * (C) Copyright 2008, Thomas Chou <thomas@wytron.com.tw>
   8  * (C) Copyright 2010, Tobias Klauser <tklauser@distanz.ch>
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License as published by
  12  * the Free Software Foundation; either version 2 of the License, or
  13  * (at your option) any later version.
  14  */
  15
  16 #include <linux/kernel.h>
  17 #include <linux/init.h>
  18 #include <linux/interrupt.h>
  19 #include <linux/module.h>
  20 #include <linux/console.h>
  21 #include <linux/tty.h>
  22 #include <linux/tty_flip.h>
  23 #include <linux/serial.h>
  24 #include <linux/serial_core.h>
  25 #include <linux/platform_device.h>
  26 #include <linux/io.h>
  27 #include <linux/altera_uart.h>
  28
  29 #define DRV_NAME "altera_uart"
  30
  31 /*
  32  * Altera UART register definitions according to the Nios UART datasheet:
  33  * http://www.altera.com/literature/ds/ds_nios_uart.pdf
  34  */
  35
  36 #define ALTERA_UART_SIZE                32
  37
  38 #define ALTERA_UART_RXDATA_REG          0
  39 #define ALTERA_UART_TXDATA_REG          4
  40 #define ALTERA_UART_STATUS_REG          8
  41 #define ALTERA_UART_CONTROL_REG         12
  42 #define ALTERA_UART_DIVISOR_REG         16
  43 #define ALTERA_UART_EOP_REG             20
  44
  45 #define ALTERA_UART_STATUS_PE_MSK       0x0001  /* parity error */
  46 #define ALTERA_UART_STATUS_FE_MSK       0x0002  /* framing error */
  47 #define ALTERA_UART_STATUS_BRK_MSK      0x0004  /* break */
  48 #define ALTERA_UART_STATUS_ROE_MSK      0x0008  /* RX overrun error */
  49 #define ALTERA_UART_STATUS_TOE_MSK      0x0010  /* TX overrun error */
  50 #define ALTERA_UART_STATUS_TMT_MSK      0x0020  /* TX shift register state */
  51 #define ALTERA_UART_STATUS_TRDY_MSK     0x0040  /* TX ready */
  52 #define ALTERA_UART_STATUS_RRDY_MSK     0x0080  /* RX ready */
  53 #define ALTERA_UART_STATUS_E_MSK        0x0100  /* exception condition */
  54 #define ALTERA_UART_STATUS_DCTS_MSK     0x0400  /* CTS logic-level change */
  55 #define ALTERA_UART_STATUS_CTS_MSK      0x0800  /* CTS logic state */
  56 #define ALTERA_UART_STATUS_EOP_MSK      0x1000  /* EOP written/read */
  57
  58                                                 /* Enable interrupt on... */
  59 #define ALTERA_UART_CONTROL_PE_MSK      0x0001  /* ...parity error */
  60 #define ALTERA_UART_CONTROL_FE_MSK      0x0002  /* ...framing error */
  61 #define ALTERA_UART_CONTROL_BRK_MSK     0x0004  /* ...break */
  62 #define ALTERA_UART_CONTROL_ROE_MSK     0x0008  /* ...RX overrun */
  63 #define ALTERA_UART_CONTROL_TOE_MSK     0x0010  /* ...TX overrun */
  64 #define ALTERA_UART_CONTROL_TMT_MSK     0x0020  /* ...TX shift register empty */
  65 #define ALTERA_UART_CONTROL_TRDY_MSK    0x0040  /* ...TX ready */
  66 #define ALTERA_UART_CONTROL_RRDY_MSK    0x0080  /* ...RX ready */
  67 #define ALTERA_UART_CONTROL_E_MSK       0x0100  /* ...exception*/
  68
  69 #define ALTERA_UART_CONTROL_TRBK_MSK    0x0200  /* TX break */
  70 #define ALTERA_UART_CONTROL_DCTS_MSK    0x0400  /* Interrupt on CTS change */
  71 #define ALTERA_UART_CONTROL_RTS_MSK     0x0800  /* RTS signal */
  72 #define ALTERA_UART_CONTROL_EOP_MSK     0x1000  /* Interrupt on EOP */
  73
  74 /*
  75  * Local per-uart structure.
  76  */
  77 struct altera_uart {
  78         struct uart_port port;
  79         unsigned int sigs;      /* Local copy of line sigs */
  80         unsigned short imr;     /* Local IMR mirror */
  81 };
  82
  83 static unsigned int altera_uart_tx_empty(struct uart_port *port)
  84 {
  85         return (readl(port->membase + ALTERA_UART_STATUS_REG) &
  86                 ALTERA_UART_STATUS_TMT_MSK) ? TIOCSER_TEMT : 0;
  87 }
  88
  89 static unsigned int altera_uart_get_mctrl(struct uart_port *port)
  90 {
  91         struct altera_uart *pp = container_of(port, struct altera_uart, port);
  92         unsigned int sigs;
  93
  94         sigs =
  95             (readl(port->membase + ALTERA_UART_STATUS_REG) &
  96              ALTERA_UART_STATUS_CTS_MSK) ? TIOCM_CTS : 0;
  97         sigs |= (pp->sigs & TIOCM_RTS);
  98
  99         return sigs;
 100 }
 101
 102 static void altera_uart_set_mctrl(struct uart_port *port, unsigned int sigs)
 103 {
 104         struct altera_uart *pp = container_of(port, struct altera_uart, port);
 105
 106         pp->sigs = sigs;
 107         if (sigs & TIOCM_RTS)
 108                 pp->imr |= ALTERA_UART_CONTROL_RTS_MSK;
 109         else
 110                 pp->imr &= ~ALTERA_UART_CONTROL_RTS_MSK;
 111         writel(pp->imr, port->membase + ALTERA_UART_CONTROL_REG);
 112 }
 113
 114 static void altera_uart_start_tx(struct uart_port *port)
 115 {
 116         struct altera_uart *pp = container_of(port, struct altera_uart, port);
 117
 118         pp->imr |= ALTERA_UART_CONTROL_TRDY_MSK;
 119         writel(pp->imr, port->membase + ALTERA_UART_CONTROL_REG);
 120 }
 121
 122 static void altera_uart_stop_tx(struct uart_port *port)
 123 {
 124         struct altera_uart *pp = container_of(port, struct altera_uart, port);
 125
 126         pp->imr &= ~ALTERA_UART_CONTROL_TRDY_MSK;
 127         writel(pp->imr, port->membase + ALTERA_UART_CONTROL_REG);
 128 }
 129
 130 static void altera_uart_stop_rx(struct uart_port *port)
 131 {
 132         struct altera_uart *pp = container_of(port, struct altera_uart, port);
 133
 134         pp->imr &= ~ALTERA_UART_CONTROL_RRDY_MSK;
 135         writel(pp->imr, port->membase + ALTERA_UART_CONTROL_REG);
 136 }
 137
 138 static void altera_uart_break_ctl(struct uart_port *port, int break_state)
 139 {
 140         struct altera_uart *pp = container_of(port, struct altera_uart, port);
 141         unsigned long flags;
 142
 143         spin_lock_irqsave(&port->lock, flags);
 144         if (break_state == -1)
 145                 pp->imr |= ALTERA_UART_CONTROL_TRBK_MSK;
 146         else
 147                 pp->imr &= ~ALTERA_UART_CONTROL_TRBK_MSK;
 148         writel(pp->imr, port->membase + ALTERA_UART_CONTROL_REG);
 149         spin_unlock_irqrestore(&port->lock, flags);
 150 }
 151
 152 static void altera_uart_enable_ms(struct uart_port *port)
 153 {
 154 }
 155
 156 static void altera_uart_set_termios(struct uart_port *port,
 157                                     struct ktermios *termios,
 158                                     struct ktermios *old)
 159 {
 160         unsigned long flags;
 161         unsigned int baud, baudclk;
 162
 163         baud = uart_get_baud_rate(port, termios, old, 0, 4000000);
 164         baudclk = port->uartclk / baud;
 165
 166         if (old)
 167                 tty_termios_copy_hw(termios, old);
 168         tty_termios_encode_baud_rate(termios, baud, baud);
 169
 170         spin_lock_irqsave(&port->lock, flags);
 171         writel(baudclk, port->membase + ALTERA_UART_DIVISOR_REG);
 172         spin_unlock_irqrestore(&port->lock, flags);
 173 }
 174
 175 static void altera_uart_rx_chars(struct altera_uart *pp)
 176 {
 177         struct uart_port *port = &pp->port;
 178         unsigned char ch, flag;
 179         unsigned short status;
 180
 181         while ((status = readl(port->membase + ALTERA_UART_STATUS_REG)) &
 182                ALTERA_UART_STATUS_RRDY_MSK) {
 183                 ch = readl(port->membase + ALTERA_UART_RXDATA_REG);
 184                 flag = TTY_NORMAL;
 185                 port->icount.rx++;
 186
 187                 if (status & ALTERA_UART_STATUS_E_MSK) {
 188                         writel(status, port->membase + ALTERA_UART_STATUS_REG);
 189
 190                         if (status & ALTERA_UART_STATUS_BRK_MSK) {
 191                                 port->icount.brk++;
 192                                 if (uart_handle_break(port))
 193                                         continue;
 194                         } else if (status & ALTERA_UART_STATUS_PE_MSK) {
 195                                 port->icount.parity++;
 196                         } else if (status & ALTERA_UART_STATUS_ROE_MSK) {
 197                                 port->icount.overrun++;
 198                         } else if (status & ALTERA_UART_STATUS_FE_MSK) {
 199                                 port->icount.frame++;
 200                         }
 201
 202                         status &= port->read_status_mask;
 203
 204                         if (status & ALTERA_UART_STATUS_BRK_MSK)
 205                                 flag = TTY_BREAK;
 206                         else if (status & ALTERA_UART_STATUS_PE_MSK)
 207                                 flag = TTY_PARITY;
 208                         else if (status & ALTERA_UART_STATUS_FE_MSK)
 209                                 flag = TTY_FRAME;
 210                 }
 211
 212                 if (uart_handle_sysrq_char(port, ch))
 213                         continue;
 214                 uart_insert_char(port, status, ALTERA_UART_STATUS_ROE_MSK, ch,
 215                                  flag);
 216         }
 217
 218         tty_flip_buffer_push(port->state->port.tty);
 219 }
 220
 221 static void altera_uart_tx_chars(struct altera_uart *pp)
 222 {
 223         struct uart_port *port = &pp->port;
 224         struct circ_buf *xmit = &port->state->xmit;
 225
 226         if (port->x_char) {
 227                 /* Send special char - probably flow control */
 228                 writel(port->x_char, port->membase + ALTERA_UART_TXDATA_REG);
 229                 port->x_char = 0;
 230                 port->icount.tx++;
 231                 return;
 232         }
 233
 234         while (readl(port->membase + ALTERA_UART_STATUS_REG) &
 235                ALTERA_UART_STATUS_TRDY_MSK) {
 236                 if (xmit->head == xmit->tail)
 237                         break;
 238                 writel(xmit->buf[xmit->tail],
 239                        port->membase + ALTERA_UART_TXDATA_REG);
 240                 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 241                 port->icount.tx++;
 242         }
 243
 244         if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 245                 uart_write_wakeup(port);
 246
 247         if (xmit->head == xmit->tail) {
 248                 pp->imr &= ~ALTERA_UART_CONTROL_TRDY_MSK;
 249                 writel(pp->imr, port->membase + ALTERA_UART_CONTROL_REG);
 250         }
 251 }
 252
 253 static irqreturn_t altera_uart_interrupt(int irq, void *data)
 254 {
 255         struct uart_port *port = data;
 256         struct altera_uart *pp = container_of(port, struct altera_uart, port);
 257         unsigned int isr;
 258
 259         isr = readl(port->membase + ALTERA_UART_STATUS_REG) & pp->imr;
 260
 261         spin_lock(&port->lock);
 262         if (isr & ALTERA_UART_STATUS_RRDY_MSK)
 263                 altera_uart_rx_chars(pp);
 264         if (isr & ALTERA_UART_STATUS_TRDY_MSK)
 265                 altera_uart_tx_chars(pp);
 266         spin_unlock(&port->lock);
 267
 268         return IRQ_RETVAL(isr);
 269 }
 270
 271 static void altera_uart_config_port(struct uart_port *port, int flags)
 272 {
 273         port->type = PORT_ALTERA_UART;
 274
 275         /* Clear mask, so no surprise interrupts. */
 276         writel(0, port->membase + ALTERA_UART_CONTROL_REG);
 277         /* Clear status register */
 278         writel(0, port->membase + ALTERA_UART_STATUS_REG);
 279 }
 280
 281 static int altera_uart_startup(struct uart_port *port)
 282 {
 283         struct altera_uart *pp = container_of(port, struct altera_uart, port);
 284         unsigned long flags;
 285         int ret;
 286
 287         ret = request_irq(port->irq, altera_uart_interrupt, IRQF_DISABLED,
 288                         DRV_NAME, port);
 289         if (ret) {
 290                 pr_err(DRV_NAME ": unable to attach Altera UART %d "
 291                        "interrupt vector=%d\n", port->line, port->irq);
 292                 return ret;
 293         }
 294
 295         spin_lock_irqsave(&port->lock, flags);
 296
 297         /* Enable RX interrupts now */
 298         pp->imr = ALTERA_UART_CONTROL_RRDY_MSK;
 299         writel(pp->imr, port->membase + ALTERA_UART_CONTROL_REG);
 300
 301         spin_unlock_irqrestore(&port->lock, flags);
 302
 303         return 0;
 304 }
 305
 306 static void altera_uart_shutdown(struct uart_port *port)
 307 {
 308         struct altera_uart *pp = container_of(port, struct altera_uart, port);
 309         unsigned long flags;
 310
 311         spin_lock_irqsave(&port->lock, flags);
 312
 313         /* Disable all interrupts now */
 314         pp->imr = 0;
 315         writel(pp->imr, port->membase + ALTERA_UART_CONTROL_REG);
 316
 317         spin_unlock_irqrestore(&port->lock, flags);
 318
 319         free_irq(port->irq, port);
 320 }
 321
 322 static const char *altera_uart_type(struct uart_port *port)
 323 {
 324         return (port->type == PORT_ALTERA_UART) ? "Altera UART" : NULL;
 325 }
 326
 327 static int altera_uart_request_port(struct uart_port *port)
 328 {
 329         /* UARTs always present */
 330         return 0;
 331 }
 332
 333 static void altera_uart_release_port(struct uart_port *port)
 334 {
 335         /* Nothing to release... */
 336 }
 337
 338 static int altera_uart_verify_port(struct uart_port *port,
 339                                    struct serial_struct *ser)
 340 {
 341         if ((ser->type != PORT_UNKNOWN) && (ser->type != PORT_ALTERA_UART))
 342                 return -EINVAL;
 343         return 0;
 344 }
 345
 346 /*
 347  *      Define the basic serial functions we support.
 348  */
 349 static struct uart_ops altera_uart_ops = {
 350         .tx_empty       = altera_uart_tx_empty,
 351         .get_mctrl      = altera_uart_get_mctrl,
 352         .set_mctrl      = altera_uart_set_mctrl,
 353         .start_tx       = altera_uart_start_tx,
 354         .stop_tx        = altera_uart_stop_tx,
 355         .stop_rx        = altera_uart_stop_rx,
 356         .enable_ms      = altera_uart_enable_ms,
 357         .break_ctl      = altera_uart_break_ctl,
 358         .startup        = altera_uart_startup,
 359         .shutdown       = altera_uart_shutdown,
 360         .set_termios    = altera_uart_set_termios,
 361         .type           = altera_uart_type,
 362         .request_port   = altera_uart_request_port,
 363         .release_port   = altera_uart_release_port,
 364         .config_port    = altera_uart_config_port,
 365         .verify_port    = altera_uart_verify_port,
 366 };
 367
 368 static struct altera_uart altera_uart_ports[CONFIG_SERIAL_ALTERA_UART_MAXPORTS];
 369
 370 #if defined(CONFIG_SERIAL_ALTERA_UART_CONSOLE)
 371
 372 int __init early_altera_uart_setup(struct altera_uart_platform_uart *platp)
 373 {
 374         struct uart_port *port;
 375         int i;
 376
 377         for (i = 0; i < CONFIG_SERIAL_ALTERA_UART_MAXPORTS && platp[i].mapbase; i++) {
 378                 port = &altera_uart_ports[i].port;
 379
 380                 port->line = i;
 381                 port->type = PORT_ALTERA_UART;
 382                 port->mapbase = platp[i].mapbase;
 383                 port->membase = ioremap(port->mapbase, ALTERA_UART_SIZE);
 384                 port->iotype = SERIAL_IO_MEM;
 385                 port->irq = platp[i].irq;
 386                 port->uartclk = platp[i].uartclk;
 387                 port->flags = ASYNC_BOOT_AUTOCONF;
 388                 port->ops = &altera_uart_ops;
 389         }
 390
 391         return 0;
 392 }
 393
 394 static void altera_uart_console_putc(struct uart_port *port, const char c)
 395 {
 396         while (!(readl(port->membase + ALTERA_UART_STATUS_REG) &
 397                  ALTERA_UART_STATUS_TRDY_MSK))
 398                 cpu_relax();
 399
 400         writel(c, port->membase + ALTERA_UART_TXDATA_REG);
 401 }
 402
 403 static void altera_uart_console_write(struct console *co, const char *s,
 404                                       unsigned int count)
 405 {
 406         struct uart_port *port = &(altera_uart_ports + co->index)->port;
 407
 408         for (; count; count--, s++) {
 409                 altera_uart_console_putc(port, *s);
 410                 if (*s == '\n')
 411                         altera_uart_console_putc(port, '\r');
 412         }
 413 }
 414
 415 static int __init altera_uart_console_setup(struct console *co, char *options)
 416 {
 417         struct uart_port *port;
 418         int baud = CONFIG_SERIAL_ALTERA_UART_BAUDRATE;
 419         int bits = 8;
 420         int parity = 'n';
 421         int flow = 'n';
 422
 423         if (co->index < 0 || co->index >= CONFIG_SERIAL_ALTERA_UART_MAXPORTS)
 424                 return -EINVAL;
 425         port = &altera_uart_ports[co->index].port;
 426         if (port->membase == 0)
 427                 return -ENODEV;
 428
 429         if (options)
 430                 uart_parse_options(options, &baud, &parity, &bits, &flow);
 431
 432         return uart_set_options(port, co, baud, parity, bits, flow);
 433 }
 434
 435 static struct uart_driver altera_uart_driver;
 436
 437 static struct console altera_uart_console = {
 438         .name   = "ttyS",
 439         .write  = altera_uart_console_write,
 440         .device = uart_console_device,
 441         .setup  = altera_uart_console_setup,
 442         .flags  = CON_PRINTBUFFER,
 443         .index  = -1,
 444         .data   = &altera_uart_driver,
 445 };
 446
 447 static int __init altera_uart_console_init(void)
 448 {
 449         register_console(&altera_uart_console);
 450         return 0;
 451 }
 452
 453 console_initcall(altera_uart_console_init);
 454
 455 #define ALTERA_UART_CONSOLE     (&altera_uart_console)
 456
 457 #else
 458
 459 #define ALTERA_UART_CONSOLE     NULL
 460
 461 #endif /* CONFIG_ALTERA_UART_CONSOLE */
 462
 463 /*
 464  *      Define the altera_uart UART driver structure.
 465  */
 466 static struct uart_driver altera_uart_driver = {
 467         .owner          = THIS_MODULE,
 468         .driver_name    = DRV_NAME,
 469         .dev_name       = "ttyS",
 470         .major          = TTY_MAJOR,
 471         .minor          = 64,
 472         .nr             = CONFIG_SERIAL_ALTERA_UART_MAXPORTS,
 473         .cons           = ALTERA_UART_CONSOLE,
 474 };
 475
 476 static int __devinit altera_uart_probe(struct platform_device *pdev)
 477 {
 478         struct altera_uart_platform_uart *platp = pdev->dev.platform_data;
 479         struct uart_port *port;
 480         int i;
 481
 482         for (i = 0; i < CONFIG_SERIAL_ALTERA_UART_MAXPORTS && platp[i].mapbase; i++) {
 483                 port = &altera_uart_ports[i].port;
 484
 485                 port->line = i;
 486                 port->type = PORT_ALTERA_UART;
 487                 port->mapbase = platp[i].mapbase;
 488                 port->membase = ioremap(port->mapbase, ALTERA_UART_SIZE);
 489                 port->iotype = SERIAL_IO_MEM;
 490                 port->irq = platp[i].irq;
 491                 port->uartclk = platp[i].uartclk;
 492                 port->ops = &altera_uart_ops;
 493                 port->flags = ASYNC_BOOT_AUTOCONF;
 494
 495                 uart_add_one_port(&altera_uart_driver, port);
 496         }
 497
 498         return 0;
 499 }
 500
 501 static int __devexit altera_uart_remove(struct platform_device *pdev)
 502 {
 503         struct uart_port *port;
 504         int i;
 505
 506         for (i = 0; i < CONFIG_SERIAL_ALTERA_UART_MAXPORTS; i++) {
 507                 port = &altera_uart_ports[i].port;
 508                 if (port)
 509                         uart_remove_one_port(&altera_uart_driver, port);
 510         }
 511
 512         return 0;
 513 }
 514
 515 static struct platform_driver altera_uart_platform_driver = {
 516         .probe  = altera_uart_probe,
 517         .remove = __devexit_p(altera_uart_remove),
 518         .driver = {
 519                 .name   = DRV_NAME,
 520                 .owner  = THIS_MODULE,
 521                 .pm     = NULL,
 522         },
 523 };
 524
 525 static int __init altera_uart_init(void)
 526 {
 527         int rc;
 528
 529         rc = uart_register_driver(&altera_uart_driver);
 530         if (rc)
 531                 return rc;
 532         rc = platform_driver_register(&altera_uart_platform_driver);
 533         if (rc) {
 534                 uart_unregister_driver(&altera_uart_driver);
 535                 return rc;
 536         }
 537         return 0;
 538 }
 539
 540 static void __exit altera_uart_exit(void)
 541 {
 542         platform_driver_unregister(&altera_uart_platform_driver);
 543         uart_unregister_driver(&altera_uart_driver);
 544 }
 545
 546 module_init(altera_uart_init);
 547 module_exit(altera_uart_exit);
 548
 549 MODULE_DESCRIPTION("Altera UART driver");
 550 MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
 551 MODULE_LICENSE("GPL");
 552 MODULE_ALIAS("platform:" DRV_NAME);