linux/drivers/tty/serial/timbuart.c
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   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
  36struct 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
  44static int baudrates[] = {9600, 19200, 38400, 57600, 115200, 230400, 460800,
  45        921600, 1843200, 3250000};
  46
  47static void timbuart_mctrl_check(struct uart_port *port, u32 isr, u32 *ier);
  48
  49static irqreturn_t timbuart_handleinterrupt(int irq, void *devid);
  50
  51static 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
  58static 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
  65static 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
  74static 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
  81static 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
  92static 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
 110static 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
 131static 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
 165static 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
 187static 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
 211static 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
 222static 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
 232static 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
 247static void timbuart_break_ctl(struct uart_port *port, int ctl)
 248{
 249        /* N/A */
 250}
 251
 252static int timbuart_startup(struct uart_port *port)
 253{
 254        struct timbuart_port *uart =
 255                container_of(port, struct timbuart_port, port);
 256
 257        dev_dbg(port->dev, "%s\n", __func__);
 258
 259        iowrite8(TIMBUART_CTRL_FLSHRX, port->membase + TIMBUART_CTRL);
 260        iowrite32(0x1ff, port->membase + TIMBUART_ISR);
 261        /* Enable all but TX interrupts */
 262        iowrite32(RXBAF | RXBF | RXTT | CTS_DELTA,
 263                port->membase + TIMBUART_IER);
 264
 265        return request_irq(port->irq, timbuart_handleinterrupt, IRQF_SHARED,
 266                "timb-uart", uart);
 267}
 268
 269static void timbuart_shutdown(struct uart_port *port)
 270{
 271        struct timbuart_port *uart =
 272                container_of(port, struct timbuart_port, port);
 273        dev_dbg(port->dev, "%s\n", __func__);
 274        free_irq(port->irq, uart);
 275        iowrite32(0, port->membase + TIMBUART_IER);
 276
 277        timbuart_flush_buffer(port);
 278}
 279
 280static 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
 291static 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
 319static 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 */
 327static 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
 341static 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
 361static 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 */
 382static 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
 390static 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
 397static const 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        .break_ctl = timbuart_break_ctl,
 406        .startup = timbuart_startup,
 407        .shutdown = timbuart_shutdown,
 408        .set_termios = timbuart_set_termios,
 409        .type = timbuart_type,
 410        .release_port = timbuart_release_port,
 411        .request_port = timbuart_request_port,
 412        .config_port = timbuart_config_port,
 413        .verify_port = timbuart_verify_port
 414};
 415
 416static struct uart_driver timbuart_driver = {
 417        .owner = THIS_MODULE,
 418        .driver_name = "timberdale_uart",
 419        .dev_name = "ttyTU",
 420        .major = TIMBUART_MAJOR,
 421        .minor = TIMBUART_MINOR,
 422        .nr = 1
 423};
 424
 425static int timbuart_probe(struct platform_device *dev)
 426{
 427        int err, irq;
 428        struct timbuart_port *uart;
 429        struct resource *iomem;
 430
 431        dev_dbg(&dev->dev, "%s\n", __func__);
 432
 433        uart = kzalloc(sizeof(*uart), GFP_KERNEL);
 434        if (!uart) {
 435                err = -EINVAL;
 436                goto err_mem;
 437        }
 438
 439        uart->usedma = 0;
 440
 441        uart->port.uartclk = 3250000 * 16;
 442        uart->port.fifosize  = TIMBUART_FIFO_SIZE;
 443        uart->port.regshift  = 2;
 444        uart->port.iotype  = UPIO_MEM;
 445        uart->port.ops = &timbuart_ops;
 446        uart->port.irq = 0;
 447        uart->port.flags = UPF_BOOT_AUTOCONF | UPF_IOREMAP;
 448        uart->port.line  = 0;
 449        uart->port.dev  = &dev->dev;
 450
 451        iomem = platform_get_resource(dev, IORESOURCE_MEM, 0);
 452        if (!iomem) {
 453                err = -ENOMEM;
 454                goto err_register;
 455        }
 456        uart->port.mapbase = iomem->start;
 457        uart->port.membase = NULL;
 458
 459        irq = platform_get_irq(dev, 0);
 460        if (irq < 0) {
 461                err = -EINVAL;
 462                goto err_register;
 463        }
 464        uart->port.irq = irq;
 465
 466        tasklet_init(&uart->tasklet, timbuart_tasklet, (unsigned long)uart);
 467
 468        err = uart_register_driver(&timbuart_driver);
 469        if (err)
 470                goto err_register;
 471
 472        err = uart_add_one_port(&timbuart_driver, &uart->port);
 473        if (err)
 474                goto err_add_port;
 475
 476        platform_set_drvdata(dev, uart);
 477
 478        return 0;
 479
 480err_add_port:
 481        uart_unregister_driver(&timbuart_driver);
 482err_register:
 483        kfree(uart);
 484err_mem:
 485        printk(KERN_ERR "timberdale: Failed to register Timberdale UART: %d\n",
 486                err);
 487
 488        return err;
 489}
 490
 491static int timbuart_remove(struct platform_device *dev)
 492{
 493        struct timbuart_port *uart = platform_get_drvdata(dev);
 494
 495        tasklet_kill(&uart->tasklet);
 496        uart_remove_one_port(&timbuart_driver, &uart->port);
 497        uart_unregister_driver(&timbuart_driver);
 498        kfree(uart);
 499
 500        return 0;
 501}
 502
 503static struct platform_driver timbuart_platform_driver = {
 504        .driver = {
 505                .name   = "timb-uart",
 506        },
 507        .probe          = timbuart_probe,
 508        .remove         = timbuart_remove,
 509};
 510
 511module_platform_driver(timbuart_platform_driver);
 512
 513MODULE_DESCRIPTION("Timberdale UART driver");
 514MODULE_LICENSE("GPL v2");
 515MODULE_ALIAS("platform:timb-uart");
 516
 517