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