drivers/tty/serial/timbuart.c

   1 /*
   2  * timbuart.c timberdale FPGA UART driver
   3  * Copyright (c) 2009 Intel Corporation
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  17  */
  18
  19 /* Supports:
  20  * Timberdale FPGA UART
  21  */
  22
  23 #include <linux/pci.h>
  24 #include <linux/interrupt.h>
  25 #include <linux/serial_core.h>
  26 #include <linux/tty.h>
  27 #include <linux/tty_flip.h>
  28 #include <linux/kernel.h>
  29 #include <linux/platform_device.h>
  30 #include <linux/ioport.h>
  31 #include <linux/slab.h>
  32
  33 #include "timbuart.h"
  34
  35 struct timbuart_port {
  36         struct uart_port        port;
  37         struct tasklet_struct   tasklet;
  38         int                     usedma;
  39         u32                     last_ier;
  40         struct platform_device  *dev;
  41 };
  42
  43 static int baudrates[] = {9600, 19200, 38400, 57600, 115200, 230400, 460800,
  44         921600, 1843200, 3250000};
  45
  46 static void timbuart_mctrl_check(struct uart_port *port, u32 isr, u32 *ier);
  47
  48 static irqreturn_t timbuart_handleinterrupt(int irq, void *devid);
  49
  50 static void timbuart_stop_rx(struct uart_port *port)
  51 {
  52         /* spin lock held by upper layer, disable all RX interrupts */
  53         u32 ier = ioread32(port->membase + TIMBUART_IER) & ~RXFLAGS;
  54         iowrite32(ier, port->membase + TIMBUART_IER);
  55 }
  56
  57 static void timbuart_stop_tx(struct uart_port *port)
  58 {
  59         /* spinlock held by upper layer, disable TX interrupt */
  60         u32 ier = ioread32(port->membase + TIMBUART_IER) & ~TXBAE;
  61         iowrite32(ier, port->membase + TIMBUART_IER);
  62 }
  63
  64 static void timbuart_start_tx(struct uart_port *port)
  65 {
  66         struct timbuart_port *uart =
  67                 container_of(port, struct timbuart_port, port);
  68
  69         /* do not transfer anything here -> fire off the tasklet */
  70         tasklet_schedule(&uart->tasklet);
  71 }
  72
  73 static unsigned int timbuart_tx_empty(struct uart_port *port)
  74 {
  75         u32 isr = ioread32(port->membase + TIMBUART_ISR);
  76
  77         return (isr & TXBE) ? TIOCSER_TEMT : 0;
  78 }
  79
  80 static void timbuart_flush_buffer(struct uart_port *port)
  81 {
  82         if (!timbuart_tx_empty(port)) {
  83                 u8 ctl = ioread8(port->membase + TIMBUART_CTRL) |
  84                         TIMBUART_CTRL_FLSHTX;
  85
  86                 iowrite8(ctl, port->membase + TIMBUART_CTRL);
  87                 iowrite32(TXBF, port->membase + TIMBUART_ISR);
  88         }
  89 }
  90
  91 static void timbuart_rx_chars(struct uart_port *port)
  92 {
  93         struct tty_struct *tty = port->state->port.tty;
  94
  95         while (ioread32(port->membase + TIMBUART_ISR) & RXDP) {
  96                 u8 ch = ioread8(port->membase + TIMBUART_RXFIFO);
  97                 port->icount.rx++;
  98                 tty_insert_flip_char(tty, ch, TTY_NORMAL);
  99         }
 100
 101         spin_unlock(&port->lock);
 102         tty_flip_buffer_push(port->state->port.tty);
 103         spin_lock(&port->lock);
 104
 105         dev_dbg(port->dev, "%s - total read %d bytes\n",
 106                 __func__, port->icount.rx);
 107 }
 108
 109 static void timbuart_tx_chars(struct uart_port *port)
 110 {
 111         struct circ_buf *xmit = &port->state->xmit;
 112
 113         while (!(ioread32(port->membase + TIMBUART_ISR) & TXBF) &&
 114                 !uart_circ_empty(xmit)) {
 115                 iowrite8(xmit->buf[xmit->tail],
 116                         port->membase + TIMBUART_TXFIFO);
 117                 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 118                 port->icount.tx++;
 119         }
 120
 121         dev_dbg(port->dev,
 122                 "%s - total written %d bytes, CTL: %x, RTS: %x, baud: %x\n",
 123                  __func__,
 124                 port->icount.tx,
 125                 ioread8(port->membase + TIMBUART_CTRL),
 126                 port->mctrl & TIOCM_RTS,
 127                 ioread8(port->membase + TIMBUART_BAUDRATE));
 128 }
 129
 130 static void timbuart_handle_tx_port(struct uart_port *port, u32 isr, u32 *ier)
 131 {
 132         struct timbuart_port *uart =
 133                 container_of(port, struct timbuart_port, port);
 134         struct circ_buf *xmit = &port->state->xmit;
 135
 136         if (uart_circ_empty(xmit) || uart_tx_stopped(port))
 137                 return;
 138
 139         if (port->x_char)
 140                 return;
 141
 142         if (isr & TXFLAGS) {
 143                 timbuart_tx_chars(port);
 144                 /* clear all TX interrupts */
 145                 iowrite32(TXFLAGS, port->membase + TIMBUART_ISR);
 146
 147                 if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 148                         uart_write_wakeup(port);
 149         } else
 150                 /* Re-enable any tx interrupt */
 151                 *ier |= uart->last_ier & TXFLAGS;
 152
 153         /* enable interrupts if there are chars in the transmit buffer,
 154          * Or if we delivered some bytes and want the almost empty interrupt
 155          * we wake up the upper layer later when we got the interrupt
 156          * to give it some time to go out...
 157          */
 158         if (!uart_circ_empty(xmit))
 159                 *ier |= TXBAE;
 160
 161         dev_dbg(port->dev, "%s - leaving\n", __func__);
 162 }
 163
 164 void timbuart_handle_rx_port(struct uart_port *port, u32 isr, u32 *ier)
 165 {
 166         if (isr & RXFLAGS) {
 167                 /* Some RX status is set */
 168                 if (isr & RXBF) {
 169                         u8 ctl = ioread8(port->membase + TIMBUART_CTRL) |
 170                                 TIMBUART_CTRL_FLSHRX;
 171                         iowrite8(ctl, port->membase + TIMBUART_CTRL);
 172                         port->icount.overrun++;
 173                 } else if (isr & (RXDP))
 174                         timbuart_rx_chars(port);
 175
 176                 /* ack all RX interrupts */
 177                 iowrite32(RXFLAGS, port->membase + TIMBUART_ISR);
 178         }
 179
 180         /* always have the RX interrupts enabled */
 181         *ier |= RXBAF | RXBF | RXTT;
 182
 183         dev_dbg(port->dev, "%s - leaving\n", __func__);
 184 }
 185
 186 void timbuart_tasklet(unsigned long arg)
 187 {
 188         struct timbuart_port *uart = (struct timbuart_port *)arg;
 189         u32 isr, ier = 0;
 190
 191         spin_lock(&uart->port.lock);
 192
 193         isr = ioread32(uart->port.membase + TIMBUART_ISR);
 194         dev_dbg(uart->port.dev, "%s ISR: %x\n", __func__, isr);
 195
 196         if (!uart->usedma)
 197                 timbuart_handle_tx_port(&uart->port, isr, &ier);
 198
 199         timbuart_mctrl_check(&uart->port, isr, &ier);
 200
 201         if (!uart->usedma)
 202                 timbuart_handle_rx_port(&uart->port, isr, &ier);
 203
 204         iowrite32(ier, uart->port.membase + TIMBUART_IER);
 205
 206         spin_unlock(&uart->port.lock);
 207         dev_dbg(uart->port.dev, "%s leaving\n", __func__);
 208 }
 209
 210 static unsigned int timbuart_get_mctrl(struct uart_port *port)
 211 {
 212         u8 cts = ioread8(port->membase + TIMBUART_CTRL);
 213         dev_dbg(port->dev, "%s - cts %x\n", __func__, cts);
 214
 215         if (cts & TIMBUART_CTRL_CTS)
 216                 return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
 217         else
 218                 return TIOCM_DSR | TIOCM_CAR;
 219 }
 220
 221 static void timbuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
 222 {
 223         dev_dbg(port->dev, "%s - %x\n", __func__, mctrl);
 224
 225         if (mctrl & TIOCM_RTS)
 226                 iowrite8(TIMBUART_CTRL_RTS, port->membase + TIMBUART_CTRL);
 227         else
 228                 iowrite8(0, port->membase + TIMBUART_CTRL);
 229 }
 230
 231 static void timbuart_mctrl_check(struct uart_port *port, u32 isr, u32 *ier)
 232 {
 233         unsigned int cts;
 234
 235         if (isr & CTS_DELTA) {
 236                 /* ack */
 237                 iowrite32(CTS_DELTA, port->membase + TIMBUART_ISR);
 238                 cts = timbuart_get_mctrl(port);
 239                 uart_handle_cts_change(port, cts & TIOCM_CTS);
 240                 wake_up_interruptible(&port->state->port.delta_msr_wait);
 241         }
 242
 243         *ier |= CTS_DELTA;
 244 }
 245
 246 static void timbuart_enable_ms(struct uart_port *port)
 247 {
 248         /* N/A */
 249 }
 250
 251 static void timbuart_break_ctl(struct uart_port *port, int ctl)
 252 {
 253         /* N/A */
 254 }
 255
 256 static int timbuart_startup(struct uart_port *port)
 257 {
 258         struct timbuart_port *uart =
 259                 container_of(port, struct timbuart_port, port);
 260
 261         dev_dbg(port->dev, "%s\n", __func__);
 262
 263         iowrite8(TIMBUART_CTRL_FLSHRX, port->membase + TIMBUART_CTRL);
 264         iowrite32(0x1ff, port->membase + TIMBUART_ISR);
 265         /* Enable all but TX interrupts */
 266         iowrite32(RXBAF | RXBF | RXTT | CTS_DELTA,
 267                 port->membase + TIMBUART_IER);
 268
 269         return request_irq(port->irq, timbuart_handleinterrupt, IRQF_SHARED,
 270                 "timb-uart", uart);
 271 }
 272
 273 static void timbuart_shutdown(struct uart_port *port)
 274 {
 275         struct timbuart_port *uart =
 276                 container_of(port, struct timbuart_port, port);
 277         dev_dbg(port->dev, "%s\n", __func__);
 278         free_irq(port->irq, uart);
 279         iowrite32(0, port->membase + TIMBUART_IER);
 280 }
 281
 282 static int get_bindex(int baud)
 283 {
 284         int i;
 285
 286         for (i = 0; i < ARRAY_SIZE(baudrates); i++)
 287                 if (baud <= baudrates[i])
 288                         return i;
 289
 290         return -1;
 291 }
 292
 293 static void timbuart_set_termios(struct uart_port *port,
 294         struct ktermios *termios,
 295         struct ktermios *old)
 296 {
 297         unsigned int baud;
 298         short bindex;
 299         unsigned long flags;
 300
 301         baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
 302         bindex = get_bindex(baud);
 303         dev_dbg(port->dev, "%s - bindex %d\n", __func__, bindex);
 304
 305         if (bindex < 0)
 306                 bindex = 0;
 307         baud = baudrates[bindex];
 308
 309         /* The serial layer calls into this once with old = NULL when setting
 310            up initially */
 311         if (old)
 312                 tty_termios_copy_hw(termios, old);
 313         tty_termios_encode_baud_rate(termios, baud, baud);
 314
 315         spin_lock_irqsave(&port->lock, flags);
 316         iowrite8((u8)bindex, port->membase + TIMBUART_BAUDRATE);
 317         uart_update_timeout(port, termios->c_cflag, baud);
 318         spin_unlock_irqrestore(&port->lock, flags);
 319 }
 320
 321 static const char *timbuart_type(struct uart_port *port)
 322 {
 323         return port->type == PORT_UNKNOWN ? "timbuart" : NULL;
 324 }
 325
 326 /* We do not request/release mappings of the registers here,
 327  * currently it's done in the proble function.
 328  */
 329 static void timbuart_release_port(struct uart_port *port)
 330 {
 331         struct platform_device *pdev = to_platform_device(port->dev);
 332         int size =
 333                 resource_size(platform_get_resource(pdev, IORESOURCE_MEM, 0));
 334
 335         if (port->flags & UPF_IOREMAP) {
 336                 iounmap(port->membase);
 337                 port->membase = NULL;
 338         }
 339
 340         release_mem_region(port->mapbase, size);
 341 }
 342
 343 static int timbuart_request_port(struct uart_port *port)
 344 {
 345         struct platform_device *pdev = to_platform_device(port->dev);
 346         int size =
 347                 resource_size(platform_get_resource(pdev, IORESOURCE_MEM, 0));
 348
 349         if (!request_mem_region(port->mapbase, size, "timb-uart"))
 350                 return -EBUSY;
 351
 352         if (port->flags & UPF_IOREMAP) {
 353                 port->membase = ioremap(port->mapbase, size);
 354                 if (port->membase == NULL) {
 355                         release_mem_region(port->mapbase, size);
 356                         return -ENOMEM;
 357                 }
 358         }
 359
 360         return 0;
 361 }
 362
 363 static irqreturn_t timbuart_handleinterrupt(int irq, void *devid)
 364 {
 365         struct timbuart_port *uart = (struct timbuart_port *)devid;
 366
 367         if (ioread8(uart->port.membase + TIMBUART_IPR)) {
 368                 uart->last_ier = ioread32(uart->port.membase + TIMBUART_IER);
 369
 370                 /* disable interrupts, the tasklet enables them again */
 371                 iowrite32(0, uart->port.membase + TIMBUART_IER);
 372
 373                 /* fire off bottom half */
 374                 tasklet_schedule(&uart->tasklet);
 375
 376                 return IRQ_HANDLED;
 377         } else
 378                 return IRQ_NONE;
 379 }
 380
 381 /*
 382  * Configure/autoconfigure the port.
 383  */
 384 static void timbuart_config_port(struct uart_port *port, int flags)
 385 {
 386         if (flags & UART_CONFIG_TYPE) {
 387                 port->type = PORT_TIMBUART;
 388                 timbuart_request_port(port);
 389         }
 390 }
 391
 392 static int timbuart_verify_port(struct uart_port *port,
 393         struct serial_struct *ser)
 394 {
 395         /* we don't want the core code to modify any port params */
 396         return -EINVAL;
 397 }
 398
 399 static struct uart_ops timbuart_ops = {
 400         .tx_empty = timbuart_tx_empty,
 401         .set_mctrl = timbuart_set_mctrl,
 402         .get_mctrl = timbuart_get_mctrl,
 403         .stop_tx = timbuart_stop_tx,
 404         .start_tx = timbuart_start_tx,
 405         .flush_buffer = timbuart_flush_buffer,
 406         .stop_rx = timbuart_stop_rx,
 407         .enable_ms = timbuart_enable_ms,
 408         .break_ctl = timbuart_break_ctl,
 409         .startup = timbuart_startup,
 410         .shutdown = timbuart_shutdown,
 411         .set_termios = timbuart_set_termios,
 412         .type = timbuart_type,
 413         .release_port = timbuart_release_port,
 414         .request_port = timbuart_request_port,
 415         .config_port = timbuart_config_port,
 416         .verify_port = timbuart_verify_port
 417 };
 418
 419 static struct uart_driver timbuart_driver = {
 420         .owner = THIS_MODULE,
 421         .driver_name = "timberdale_uart",
 422         .dev_name = "ttyTU",
 423         .major = TIMBUART_MAJOR,
 424         .minor = TIMBUART_MINOR,
 425         .nr = 1
 426 };
 427
 428 static int __devinit timbuart_probe(struct platform_device *dev)
 429 {
 430         int err, irq;
 431         struct timbuart_port *uart;
 432         struct resource *iomem;
 433
 434         dev_dbg(&dev->dev, "%s\n", __func__);
 435
 436         uart = kzalloc(sizeof(*uart), GFP_KERNEL);
 437         if (!uart) {
 438                 err = -EINVAL;
 439                 goto err_mem;
 440         }
 441
 442         uart->usedma = 0;
 443
 444         uart->port.uartclk = 3250000 * 16;
 445         uart->port.fifosize  = TIMBUART_FIFO_SIZE;
 446         uart->port.regshift  = 2;
 447         uart->port.iotype  = UPIO_MEM;
 448         uart->port.ops = &timbuart_ops;
 449         uart->port.irq = 0;
 450         uart->port.flags = UPF_BOOT_AUTOCONF | UPF_IOREMAP;
 451         uart->port.line  = 0;
 452         uart->port.dev  = &dev->dev;
 453
 454         iomem = platform_get_resource(dev, IORESOURCE_MEM, 0);
 455         if (!iomem) {
 456                 err = -ENOMEM;
 457                 goto err_register;
 458         }
 459         uart->port.mapbase = iomem->start;
 460         uart->port.membase = NULL;
 461
 462         irq = platform_get_irq(dev, 0);
 463         if (irq < 0) {
 464                 err = -EINVAL;
 465                 goto err_register;
 466         }
 467         uart->port.irq = irq;
 468
 469         tasklet_init(&uart->tasklet, timbuart_tasklet, (unsigned long)uart);
 470
 471         err = uart_register_driver(&timbuart_driver);
 472         if (err)
 473                 goto err_register;
 474
 475         err = uart_add_one_port(&timbuart_driver, &uart->port);
 476         if (err)
 477                 goto err_add_port;
 478
 479         platform_set_drvdata(dev, uart);
 480
 481         return 0;
 482
 483 err_add_port:
 484         uart_unregister_driver(&timbuart_driver);
 485 err_register:
 486         kfree(uart);
 487 err_mem:
 488         printk(KERN_ERR "timberdale: Failed to register Timberdale UART: %d\n",
 489                 err);
 490
 491         return err;
 492 }
 493
 494 static int __devexit timbuart_remove(struct platform_device *dev)
 495 {
 496         struct timbuart_port *uart = platform_get_drvdata(dev);
 497
 498         tasklet_kill(&uart->tasklet);
 499         uart_remove_one_port(&timbuart_driver, &uart->port);
 500         uart_unregister_driver(&timbuart_driver);
 501         kfree(uart);
 502
 503         return 0;
 504 }
 505
 506 static struct platform_driver timbuart_platform_driver = {
 507         .driver = {
 508                 .name   = "timb-uart",
 509                 .owner  = THIS_MODULE,
 510         },
 511         .probe          = timbuart_probe,
 512         .remove         = __devexit_p(timbuart_remove),
 513 };
 514
 515 /*--------------------------------------------------------------------------*/
 516
 517 static int __init timbuart_init(void)
 518 {
 519         return platform_driver_register(&timbuart_platform_driver);
 520 }
 521
 522 static void __exit timbuart_exit(void)
 523 {
 524         platform_driver_unregister(&timbuart_platform_driver);
 525 }
 526
 527 module_init(timbuart_init);
 528 module_exit(timbuart_exit);
 529
 530 MODULE_DESCRIPTION("Timberdale UART driver");
 531 MODULE_LICENSE("GPL v2");
 532 MODULE_ALIAS("platform:timb-uart");
 533