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