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