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