linux/drivers/watchdog/coh901327_wdt.c
<<
>>
Prefs
   1/*
   2 * coh901327_wdt.c
   3 *
   4 * Copyright (C) 2008-2009 ST-Ericsson AB
   5 * License terms: GNU General Public License (GPL) version 2
   6 * Watchdog driver for the ST-Ericsson AB COH 901 327 IP core
   7 * Author: Linus Walleij <linus.walleij@stericsson.com>
   8 */
   9#include <linux/module.h>
  10#include <linux/types.h>
  11#include <linux/watchdog.h>
  12#include <linux/interrupt.h>
  13#include <linux/pm.h>
  14#include <linux/platform_device.h>
  15#include <linux/io.h>
  16#include <linux/bitops.h>
  17#include <linux/clk.h>
  18#include <linux/delay.h>
  19#include <linux/err.h>
  20
  21#define DRV_NAME "WDOG COH 901 327"
  22
  23/*
  24 * COH 901 327 register definitions
  25 */
  26
  27/* WDOG_FEED Register 32bit (-/W) */
  28#define U300_WDOG_FR                                                    0x00
  29#define U300_WDOG_FR_FEED_RESTART_TIMER                                 0xFEEDU
  30/* WDOG_TIMEOUT Register 32bit (R/W) */
  31#define U300_WDOG_TR                                                    0x04
  32#define U300_WDOG_TR_TIMEOUT_MASK                                       0x7FFFU
  33/* WDOG_DISABLE1 Register 32bit (-/W) */
  34#define U300_WDOG_D1R                                                   0x08
  35#define U300_WDOG_D1R_DISABLE1_DISABLE_TIMER                            0x2BADU
  36/* WDOG_DISABLE2 Register 32bit (R/W) */
  37#define U300_WDOG_D2R                                                   0x0C
  38#define U300_WDOG_D2R_DISABLE2_DISABLE_TIMER                            0xCAFEU
  39#define U300_WDOG_D2R_DISABLE_STATUS_DISABLED                           0xDABEU
  40#define U300_WDOG_D2R_DISABLE_STATUS_ENABLED                            0x0000U
  41/* WDOG_STATUS Register 32bit (R/W) */
  42#define U300_WDOG_SR                                                    0x10
  43#define U300_WDOG_SR_STATUS_TIMED_OUT                                   0xCFE8U
  44#define U300_WDOG_SR_STATUS_NORMAL                                      0x0000U
  45#define U300_WDOG_SR_RESET_STATUS_RESET                                 0xE8B4U
  46/* WDOG_COUNT Register 32bit (R/-) */
  47#define U300_WDOG_CR                                                    0x14
  48#define U300_WDOG_CR_VALID_IND                                          0x8000U
  49#define U300_WDOG_CR_VALID_STABLE                                       0x0000U
  50#define U300_WDOG_CR_COUNT_VALUE_MASK                                   0x7FFFU
  51/* WDOG_JTAGOVR Register 32bit (R/W) */
  52#define U300_WDOG_JOR                                                   0x18
  53#define U300_WDOG_JOR_JTAG_MODE_IND                                     0x0002U
  54#define U300_WDOG_JOR_JTAG_WATCHDOG_ENABLE                              0x0001U
  55/* WDOG_RESTART Register 32bit (-/W) */
  56#define U300_WDOG_RR                                                    0x1C
  57#define U300_WDOG_RR_RESTART_VALUE_RESUME                               0xACEDU
  58/* WDOG_IRQ_EVENT Register 32bit (R/W) */
  59#define U300_WDOG_IER                                                   0x20
  60#define U300_WDOG_IER_WILL_BARK_IRQ_EVENT_IND                           0x0001U
  61#define U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE                          0x0001U
  62/* WDOG_IRQ_MASK Register 32bit (R/W) */
  63#define U300_WDOG_IMR                                                   0x24
  64#define U300_WDOG_IMR_WILL_BARK_IRQ_ENABLE                              0x0001U
  65/* WDOG_IRQ_FORCE Register 32bit (R/W) */
  66#define U300_WDOG_IFR                                                   0x28
  67#define U300_WDOG_IFR_WILL_BARK_IRQ_FORCE_ENABLE                        0x0001U
  68
  69/* Default timeout in seconds = 1 minute */
  70static unsigned int margin = 60;
  71static resource_size_t phybase;
  72static resource_size_t physize;
  73static int irq;
  74static void __iomem *virtbase;
  75static struct device *parent;
  76
  77/*
  78 * The watchdog block is of course always clocked, the
  79 * clk_enable()/clk_disable() calls are mainly for performing reference
  80 * counting higher up in the clock hierarchy.
  81 */
  82static struct clk *clk;
  83
  84/*
  85 * Enabling and disabling functions.
  86 */
  87static void coh901327_enable(u16 timeout)
  88{
  89        u16 val;
  90        unsigned long freq;
  91        unsigned long delay_ns;
  92
  93        clk_enable(clk);
  94        /* Restart timer if it is disabled */
  95        val = readw(virtbase + U300_WDOG_D2R);
  96        if (val == U300_WDOG_D2R_DISABLE_STATUS_DISABLED)
  97                writew(U300_WDOG_RR_RESTART_VALUE_RESUME,
  98                       virtbase + U300_WDOG_RR);
  99        /* Acknowledge any pending interrupt so it doesn't just fire off */
 100        writew(U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE,
 101               virtbase + U300_WDOG_IER);
 102        /*
 103         * The interrupt is cleared in the 32 kHz clock domain.
 104         * Wait 3 32 kHz cycles for it to take effect
 105         */
 106        freq = clk_get_rate(clk);
 107        delay_ns = DIV_ROUND_UP(1000000000, freq); /* Freq to ns and round up */
 108        delay_ns = 3 * delay_ns; /* Wait 3 cycles */
 109        ndelay(delay_ns);
 110        /* Enable the watchdog interrupt */
 111        writew(U300_WDOG_IMR_WILL_BARK_IRQ_ENABLE, virtbase + U300_WDOG_IMR);
 112        /* Activate the watchdog timer */
 113        writew(timeout, virtbase + U300_WDOG_TR);
 114        /* Start the watchdog timer */
 115        writew(U300_WDOG_FR_FEED_RESTART_TIMER, virtbase + U300_WDOG_FR);
 116        /*
 117         * Extra read so that this change propagate in the watchdog.
 118         */
 119        (void) readw(virtbase + U300_WDOG_CR);
 120        val = readw(virtbase + U300_WDOG_D2R);
 121        clk_disable(clk);
 122        if (val != U300_WDOG_D2R_DISABLE_STATUS_ENABLED)
 123                dev_err(parent,
 124                        "%s(): watchdog not enabled! D2R value %04x\n",
 125                        __func__, val);
 126}
 127
 128static void coh901327_disable(void)
 129{
 130        u16 val;
 131
 132        clk_enable(clk);
 133        /* Disable the watchdog interrupt if it is active */
 134        writew(0x0000U, virtbase + U300_WDOG_IMR);
 135        /* If the watchdog is currently enabled, attempt to disable it */
 136        val = readw(virtbase + U300_WDOG_D2R);
 137        if (val != U300_WDOG_D2R_DISABLE_STATUS_DISABLED) {
 138                writew(U300_WDOG_D1R_DISABLE1_DISABLE_TIMER,
 139                       virtbase + U300_WDOG_D1R);
 140                writew(U300_WDOG_D2R_DISABLE2_DISABLE_TIMER,
 141                       virtbase + U300_WDOG_D2R);
 142                /* Write this twice (else problems occur) */
 143                writew(U300_WDOG_D2R_DISABLE2_DISABLE_TIMER,
 144                       virtbase + U300_WDOG_D2R);
 145        }
 146        val = readw(virtbase + U300_WDOG_D2R);
 147        clk_disable(clk);
 148        if (val != U300_WDOG_D2R_DISABLE_STATUS_DISABLED)
 149                dev_err(parent,
 150                        "%s(): watchdog not disabled! D2R value %04x\n",
 151                        __func__, val);
 152}
 153
 154static int coh901327_start(struct watchdog_device *wdt_dev)
 155{
 156        coh901327_enable(wdt_dev->timeout * 100);
 157        return 0;
 158}
 159
 160static int coh901327_stop(struct watchdog_device *wdt_dev)
 161{
 162        coh901327_disable();
 163        return 0;
 164}
 165
 166static int coh901327_ping(struct watchdog_device *wdd)
 167{
 168        clk_enable(clk);
 169        /* Feed the watchdog */
 170        writew(U300_WDOG_FR_FEED_RESTART_TIMER,
 171               virtbase + U300_WDOG_FR);
 172        clk_disable(clk);
 173        return 0;
 174}
 175
 176static int coh901327_settimeout(struct watchdog_device *wdt_dev,
 177                                unsigned int time)
 178{
 179        wdt_dev->timeout = time;
 180        clk_enable(clk);
 181        /* Set new timeout value */
 182        writew(time * 100, virtbase + U300_WDOG_TR);
 183        /* Feed the dog */
 184        writew(U300_WDOG_FR_FEED_RESTART_TIMER,
 185               virtbase + U300_WDOG_FR);
 186        clk_disable(clk);
 187        return 0;
 188}
 189
 190static unsigned int coh901327_gettimeleft(struct watchdog_device *wdt_dev)
 191{
 192        u16 val;
 193
 194        clk_enable(clk);
 195        /* Read repeatedly until the value is stable! */
 196        val = readw(virtbase + U300_WDOG_CR);
 197        while (val & U300_WDOG_CR_VALID_IND)
 198                val = readw(virtbase + U300_WDOG_CR);
 199        val &= U300_WDOG_CR_COUNT_VALUE_MASK;
 200        clk_disable(clk);
 201        if (val != 0)
 202                val /= 100;
 203
 204        return val;
 205}
 206
 207/*
 208 * This interrupt occurs 10 ms before the watchdog WILL bark.
 209 */
 210static irqreturn_t coh901327_interrupt(int irq, void *data)
 211{
 212        u16 val;
 213
 214        /*
 215         * Ack IRQ? If this occurs we're FUBAR anyway, so
 216         * just acknowledge, disable the interrupt and await the imminent end.
 217         * If you at some point need a host of callbacks to be called
 218         * when the system is about to watchdog-reset, add them here!
 219         *
 220         * NOTE: on future versions of this IP-block, it will be possible
 221         * to prevent a watchdog reset by feeding the watchdog at this
 222         * point.
 223         */
 224        clk_enable(clk);
 225        val = readw(virtbase + U300_WDOG_IER);
 226        if (val == U300_WDOG_IER_WILL_BARK_IRQ_EVENT_IND)
 227                writew(U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE,
 228                       virtbase + U300_WDOG_IER);
 229        writew(0x0000U, virtbase + U300_WDOG_IMR);
 230        clk_disable(clk);
 231        dev_crit(parent, "watchdog is barking!\n");
 232        return IRQ_HANDLED;
 233}
 234
 235static const struct watchdog_info coh901327_ident = {
 236        .options = WDIOF_CARDRESET | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 237        .identity = DRV_NAME,
 238};
 239
 240static struct watchdog_ops coh901327_ops = {
 241        .owner = THIS_MODULE,
 242        .start = coh901327_start,
 243        .stop = coh901327_stop,
 244        .ping = coh901327_ping,
 245        .set_timeout = coh901327_settimeout,
 246        .get_timeleft = coh901327_gettimeleft,
 247};
 248
 249static struct watchdog_device coh901327_wdt = {
 250        .info = &coh901327_ident,
 251        .ops = &coh901327_ops,
 252        /*
 253         * Max timeout is 327 since the 10ms
 254         * timeout register is max
 255         * 0x7FFF = 327670ms ~= 327s.
 256         */
 257        .min_timeout = 0,
 258        .max_timeout = 327,
 259};
 260
 261static int __exit coh901327_remove(struct platform_device *pdev)
 262{
 263        watchdog_unregister_device(&coh901327_wdt);
 264        coh901327_disable();
 265        free_irq(irq, pdev);
 266        clk_unprepare(clk);
 267        clk_put(clk);
 268        iounmap(virtbase);
 269        release_mem_region(phybase, physize);
 270        return 0;
 271}
 272
 273static int __init coh901327_probe(struct platform_device *pdev)
 274{
 275        int ret;
 276        u16 val;
 277        struct resource *res;
 278
 279        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 280        if (!res)
 281                return -ENOENT;
 282
 283        parent = &pdev->dev;
 284        physize = resource_size(res);
 285        phybase = res->start;
 286
 287        if (request_mem_region(phybase, physize, DRV_NAME) == NULL) {
 288                ret = -EBUSY;
 289                goto out;
 290        }
 291
 292        virtbase = ioremap(phybase, physize);
 293        if (!virtbase) {
 294                ret = -ENOMEM;
 295                goto out_no_remap;
 296        }
 297
 298        clk = clk_get(&pdev->dev, NULL);
 299        if (IS_ERR(clk)) {
 300                ret = PTR_ERR(clk);
 301                dev_err(&pdev->dev, "could not get clock\n");
 302                goto out_no_clk;
 303        }
 304        ret = clk_prepare_enable(clk);
 305        if (ret) {
 306                dev_err(&pdev->dev, "could not prepare and enable clock\n");
 307                goto out_no_clk_enable;
 308        }
 309
 310        val = readw(virtbase + U300_WDOG_SR);
 311        switch (val) {
 312        case U300_WDOG_SR_STATUS_TIMED_OUT:
 313                dev_info(&pdev->dev,
 314                        "watchdog timed out since last chip reset!\n");
 315                coh901327_wdt.bootstatus |= WDIOF_CARDRESET;
 316                /* Status will be cleared below */
 317                break;
 318        case U300_WDOG_SR_STATUS_NORMAL:
 319                dev_info(&pdev->dev,
 320                        "in normal status, no timeouts have occurred.\n");
 321                break;
 322        default:
 323                dev_info(&pdev->dev,
 324                        "contains an illegal status code (%08x)\n", val);
 325                break;
 326        }
 327
 328        val = readw(virtbase + U300_WDOG_D2R);
 329        switch (val) {
 330        case U300_WDOG_D2R_DISABLE_STATUS_DISABLED:
 331                dev_info(&pdev->dev, "currently disabled.\n");
 332                break;
 333        case U300_WDOG_D2R_DISABLE_STATUS_ENABLED:
 334                dev_info(&pdev->dev,
 335                         "currently enabled! (disabling it now)\n");
 336                coh901327_disable();
 337                break;
 338        default:
 339                dev_err(&pdev->dev,
 340                        "contains an illegal enable/disable code (%08x)\n",
 341                        val);
 342                break;
 343        }
 344
 345        /* Reset the watchdog */
 346        writew(U300_WDOG_SR_RESET_STATUS_RESET, virtbase + U300_WDOG_SR);
 347
 348        irq = platform_get_irq(pdev, 0);
 349        if (request_irq(irq, coh901327_interrupt, 0,
 350                        DRV_NAME " Bark", pdev)) {
 351                ret = -EIO;
 352                goto out_no_irq;
 353        }
 354
 355        clk_disable(clk);
 356
 357        if (margin < 1 || margin > 327)
 358                margin = 60;
 359        coh901327_wdt.timeout = margin;
 360
 361        ret = watchdog_register_device(&coh901327_wdt);
 362        if (ret == 0)
 363                dev_info(&pdev->dev,
 364                         "initialized. timer margin=%d sec\n", margin);
 365        else
 366                goto out_no_wdog;
 367
 368        return 0;
 369
 370out_no_wdog:
 371        free_irq(irq, pdev);
 372out_no_irq:
 373        clk_disable_unprepare(clk);
 374out_no_clk_enable:
 375        clk_put(clk);
 376out_no_clk:
 377        iounmap(virtbase);
 378out_no_remap:
 379        release_mem_region(phybase, SZ_4K);
 380out:
 381        return ret;
 382}
 383
 384#ifdef CONFIG_PM
 385
 386static u16 wdogenablestore;
 387static u16 irqmaskstore;
 388
 389static int coh901327_suspend(struct platform_device *pdev, pm_message_t state)
 390{
 391        irqmaskstore = readw(virtbase + U300_WDOG_IMR) & 0x0001U;
 392        wdogenablestore = readw(virtbase + U300_WDOG_D2R);
 393        /* If watchdog is on, disable it here and now */
 394        if (wdogenablestore == U300_WDOG_D2R_DISABLE_STATUS_ENABLED)
 395                coh901327_disable();
 396        return 0;
 397}
 398
 399static int coh901327_resume(struct platform_device *pdev)
 400{
 401        /* Restore the watchdog interrupt */
 402        writew(irqmaskstore, virtbase + U300_WDOG_IMR);
 403        if (wdogenablestore == U300_WDOG_D2R_DISABLE_STATUS_ENABLED) {
 404                /* Restart the watchdog timer */
 405                writew(U300_WDOG_RR_RESTART_VALUE_RESUME,
 406                       virtbase + U300_WDOG_RR);
 407                writew(U300_WDOG_FR_FEED_RESTART_TIMER,
 408                       virtbase + U300_WDOG_FR);
 409        }
 410        return 0;
 411}
 412#else
 413#define coh901327_suspend NULL
 414#define coh901327_resume  NULL
 415#endif
 416
 417/*
 418 * Mistreating the watchdog is the only way to perform a software reset of the
 419 * system on EMP platforms. So we implement this and export a symbol for it.
 420 */
 421void coh901327_watchdog_reset(void)
 422{
 423        /* Enable even if on JTAG too */
 424        writew(U300_WDOG_JOR_JTAG_WATCHDOG_ENABLE,
 425               virtbase + U300_WDOG_JOR);
 426        /*
 427         * Timeout = 5s, we have to wait for the watchdog reset to
 428         * actually take place: the watchdog will be reloaded with the
 429         * default value immediately, so we HAVE to reboot and get back
 430         * into the kernel in 30s, or the device will reboot again!
 431         * The boot loader will typically deactivate the watchdog, so we
 432         * need time enough for the boot loader to get to the point of
 433         * deactivating the watchdog before it is shut down by it.
 434         *
 435         * NOTE: on future versions of the watchdog, this restriction is
 436         * gone: the watchdog will be reloaded with a default value (1 min)
 437         * instead of last value, and you can conveniently set the watchdog
 438         * timeout to 10ms (value = 1) without any problems.
 439         */
 440        coh901327_enable(500);
 441        /* Return and await doom */
 442}
 443
 444static struct platform_driver coh901327_driver = {
 445        .driver = {
 446                .owner  = THIS_MODULE,
 447                .name   = "coh901327_wdog",
 448        },
 449        .remove         = __exit_p(coh901327_remove),
 450        .suspend        = coh901327_suspend,
 451        .resume         = coh901327_resume,
 452};
 453
 454module_platform_driver_probe(coh901327_driver, coh901327_probe);
 455
 456MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
 457MODULE_DESCRIPTION("COH 901 327 Watchdog");
 458
 459module_param(margin, uint, 0);
 460MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");
 461
 462MODULE_LICENSE("GPL");
 463MODULE_ALIAS("platform:coh901327-watchdog");
 464
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.