drivers/watchdog/coh901327_wdt.c

   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 */
  70 static unsigned int margin = 60;
  71 static int irq;
  72 static void __iomem *virtbase;
  73 static struct device *parent;
  74
  75 static struct clk *clk;
  76
  77 /*
  78  * Enabling and disabling functions.
  79  */
  80 static void coh901327_enable(u16 timeout)
  81 {
  82         u16 val;
  83         unsigned long freq;
  84         unsigned long delay_ns;
  85
  86         /* Restart timer if it is disabled */
  87         val = readw(virtbase + U300_WDOG_D2R);
  88         if (val == U300_WDOG_D2R_DISABLE_STATUS_DISABLED)
  89                 writew(U300_WDOG_RR_RESTART_VALUE_RESUME,
  90                        virtbase + U300_WDOG_RR);
  91         /* Acknowledge any pending interrupt so it doesn't just fire off */
  92         writew(U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE,
  93                virtbase + U300_WDOG_IER);
  94         /*
  95          * The interrupt is cleared in the 32 kHz clock domain.
  96          * Wait 3 32 kHz cycles for it to take effect
  97          */
  98         freq = clk_get_rate(clk);
  99         delay_ns = DIV_ROUND_UP(1000000000, freq); /* Freq to ns and round up */
 100         delay_ns = 3 * delay_ns; /* Wait 3 cycles */
 101         ndelay(delay_ns);
 102         /* Enable the watchdog interrupt */
 103         writew(U300_WDOG_IMR_WILL_BARK_IRQ_ENABLE, virtbase + U300_WDOG_IMR);
 104         /* Activate the watchdog timer */
 105         writew(timeout, virtbase + U300_WDOG_TR);
 106         /* Start the watchdog timer */
 107         writew(U300_WDOG_FR_FEED_RESTART_TIMER, virtbase + U300_WDOG_FR);
 108         /*
 109          * Extra read so that this change propagate in the watchdog.
 110          */
 111         (void) readw(virtbase + U300_WDOG_CR);
 112         val = readw(virtbase + U300_WDOG_D2R);
 113         if (val != U300_WDOG_D2R_DISABLE_STATUS_ENABLED)
 114                 dev_err(parent,
 115                         "%s(): watchdog not enabled! D2R value %04x\n",
 116                         __func__, val);
 117 }
 118
 119 static void coh901327_disable(void)
 120 {
 121         u16 val;
 122
 123         /* Disable the watchdog interrupt if it is active */
 124         writew(0x0000U, virtbase + U300_WDOG_IMR);
 125         /* If the watchdog is currently enabled, attempt to disable it */
 126         val = readw(virtbase + U300_WDOG_D2R);
 127         if (val != U300_WDOG_D2R_DISABLE_STATUS_DISABLED) {
 128                 writew(U300_WDOG_D1R_DISABLE1_DISABLE_TIMER,
 129                        virtbase + U300_WDOG_D1R);
 130                 writew(U300_WDOG_D2R_DISABLE2_DISABLE_TIMER,
 131                        virtbase + U300_WDOG_D2R);
 132                 /* Write this twice (else problems occur) */
 133                 writew(U300_WDOG_D2R_DISABLE2_DISABLE_TIMER,
 134                        virtbase + U300_WDOG_D2R);
 135         }
 136         val = readw(virtbase + U300_WDOG_D2R);
 137         if (val != U300_WDOG_D2R_DISABLE_STATUS_DISABLED)
 138                 dev_err(parent,
 139                         "%s(): watchdog not disabled! D2R value %04x\n",
 140                         __func__, val);
 141 }
 142
 143 static int coh901327_start(struct watchdog_device *wdt_dev)
 144 {
 145         coh901327_enable(wdt_dev->timeout * 100);
 146         return 0;
 147 }
 148
 149 static int coh901327_stop(struct watchdog_device *wdt_dev)
 150 {
 151         coh901327_disable();
 152         return 0;
 153 }
 154
 155 static int coh901327_ping(struct watchdog_device *wdd)
 156 {
 157         /* Feed the watchdog */
 158         writew(U300_WDOG_FR_FEED_RESTART_TIMER,
 159                virtbase + U300_WDOG_FR);
 160         return 0;
 161 }
 162
 163 static int coh901327_settimeout(struct watchdog_device *wdt_dev,
 164                                 unsigned int time)
 165 {
 166         wdt_dev->timeout = time;
 167         /* Set new timeout value */
 168         writew(time * 100, virtbase + U300_WDOG_TR);
 169         /* Feed the dog */
 170         writew(U300_WDOG_FR_FEED_RESTART_TIMER,
 171                virtbase + U300_WDOG_FR);
 172         return 0;
 173 }
 174
 175 static unsigned int coh901327_gettimeleft(struct watchdog_device *wdt_dev)
 176 {
 177         u16 val;
 178
 179         /* Read repeatedly until the value is stable! */
 180         val = readw(virtbase + U300_WDOG_CR);
 181         while (val & U300_WDOG_CR_VALID_IND)
 182                 val = readw(virtbase + U300_WDOG_CR);
 183         val &= U300_WDOG_CR_COUNT_VALUE_MASK;
 184         if (val != 0)
 185                 val /= 100;
 186
 187         return val;
 188 }
 189
 190 /*
 191  * This interrupt occurs 10 ms before the watchdog WILL bark.
 192  */
 193 static irqreturn_t coh901327_interrupt(int irq, void *data)
 194 {
 195         u16 val;
 196
 197         /*
 198          * Ack IRQ? If this occurs we're FUBAR anyway, so
 199          * just acknowledge, disable the interrupt and await the imminent end.
 200          * If you at some point need a host of callbacks to be called
 201          * when the system is about to watchdog-reset, add them here!
 202          *
 203          * NOTE: on future versions of this IP-block, it will be possible
 204          * to prevent a watchdog reset by feeding the watchdog at this
 205          * point.
 206          */
 207         val = readw(virtbase + U300_WDOG_IER);
 208         if (val == U300_WDOG_IER_WILL_BARK_IRQ_EVENT_IND)
 209                 writew(U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE,
 210                        virtbase + U300_WDOG_IER);
 211         writew(0x0000U, virtbase + U300_WDOG_IMR);
 212         dev_crit(parent, "watchdog is barking!\n");
 213         return IRQ_HANDLED;
 214 }
 215
 216 static const struct watchdog_info coh901327_ident = {
 217         .options = WDIOF_CARDRESET | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 218         .identity = DRV_NAME,
 219 };
 220
 221 static const struct watchdog_ops coh901327_ops = {
 222         .owner = THIS_MODULE,
 223         .start = coh901327_start,
 224         .stop = coh901327_stop,
 225         .ping = coh901327_ping,
 226         .set_timeout = coh901327_settimeout,
 227         .get_timeleft = coh901327_gettimeleft,
 228 };
 229
 230 static struct watchdog_device coh901327_wdt = {
 231         .info = &coh901327_ident,
 232         .ops = &coh901327_ops,
 233         /*
 234          * Max timeout is 327 since the 10ms
 235          * timeout register is max
 236          * 0x7FFF = 327670ms ~= 327s.
 237          */
 238         .min_timeout = 0,
 239         .max_timeout = 327,
 240 };
 241
 242 static int __exit coh901327_remove(struct platform_device *pdev)
 243 {
 244         watchdog_unregister_device(&coh901327_wdt);
 245         coh901327_disable();
 246         free_irq(irq, pdev);
 247         clk_disable_unprepare(clk);
 248         clk_put(clk);
 249         return 0;
 250 }
 251
 252 static int __init coh901327_probe(struct platform_device *pdev)
 253 {
 254         struct device *dev = &pdev->dev;
 255         int ret;
 256         u16 val;
 257         struct resource *res;
 258
 259         parent = dev;
 260
 261         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 262         virtbase = devm_ioremap_resource(dev, res);
 263         if (IS_ERR(virtbase))
 264                 return PTR_ERR(virtbase);
 265
 266         clk = clk_get(dev, NULL);
 267         if (IS_ERR(clk)) {
 268                 ret = PTR_ERR(clk);
 269                 dev_err(dev, "could not get clock\n");
 270                 return ret;
 271         }
 272         ret = clk_prepare_enable(clk);
 273         if (ret) {
 274                 dev_err(dev, "could not prepare and enable clock\n");
 275                 goto out_no_clk_enable;
 276         }
 277
 278         val = readw(virtbase + U300_WDOG_SR);
 279         switch (val) {
 280         case U300_WDOG_SR_STATUS_TIMED_OUT:
 281                 dev_info(dev, "watchdog timed out since last chip reset!\n");
 282                 coh901327_wdt.bootstatus |= WDIOF_CARDRESET;
 283                 /* Status will be cleared below */
 284                 break;
 285         case U300_WDOG_SR_STATUS_NORMAL:
 286                 dev_info(dev, "in normal status, no timeouts have occurred.\n");
 287                 break;
 288         default:
 289                 dev_info(dev, "contains an illegal status code (%08x)\n", val);
 290                 break;
 291         }
 292
 293         val = readw(virtbase + U300_WDOG_D2R);
 294         switch (val) {
 295         case U300_WDOG_D2R_DISABLE_STATUS_DISABLED:
 296                 dev_info(dev, "currently disabled.\n");
 297                 break;
 298         case U300_WDOG_D2R_DISABLE_STATUS_ENABLED:
 299                 dev_info(dev, "currently enabled! (disabling it now)\n");
 300                 coh901327_disable();
 301                 break;
 302         default:
 303                 dev_err(dev, "contains an illegal enable/disable code (%08x)\n",
 304                         val);
 305                 break;
 306         }
 307
 308         /* Reset the watchdog */
 309         writew(U300_WDOG_SR_RESET_STATUS_RESET, virtbase + U300_WDOG_SR);
 310
 311         irq = platform_get_irq(pdev, 0);
 312         if (request_irq(irq, coh901327_interrupt, 0,
 313                         DRV_NAME " Bark", pdev)) {
 314                 ret = -EIO;
 315                 goto out_no_irq;
 316         }
 317
 318         ret = watchdog_init_timeout(&coh901327_wdt, margin, dev);
 319         if (ret < 0)
 320                 coh901327_wdt.timeout = 60;
 321
 322         coh901327_wdt.parent = dev;
 323         ret = watchdog_register_device(&coh901327_wdt);
 324         if (ret)
 325                 goto out_no_wdog;
 326
 327         dev_info(dev, "initialized. timer margin=%d sec\n", margin);
 328         return 0;
 329
 330 out_no_wdog:
 331         free_irq(irq, pdev);
 332 out_no_irq:
 333         clk_disable_unprepare(clk);
 334 out_no_clk_enable:
 335         clk_put(clk);
 336         return ret;
 337 }
 338
 339 #ifdef CONFIG_PM
 340
 341 static u16 wdogenablestore;
 342 static u16 irqmaskstore;
 343
 344 static int coh901327_suspend(struct platform_device *pdev, pm_message_t state)
 345 {
 346         irqmaskstore = readw(virtbase + U300_WDOG_IMR) & 0x0001U;
 347         wdogenablestore = readw(virtbase + U300_WDOG_D2R);
 348         /* If watchdog is on, disable it here and now */
 349         if (wdogenablestore == U300_WDOG_D2R_DISABLE_STATUS_ENABLED)
 350                 coh901327_disable();
 351         return 0;
 352 }
 353
 354 static int coh901327_resume(struct platform_device *pdev)
 355 {
 356         /* Restore the watchdog interrupt */
 357         writew(irqmaskstore, virtbase + U300_WDOG_IMR);
 358         if (wdogenablestore == U300_WDOG_D2R_DISABLE_STATUS_ENABLED) {
 359                 /* Restart the watchdog timer */
 360                 writew(U300_WDOG_RR_RESTART_VALUE_RESUME,
 361                        virtbase + U300_WDOG_RR);
 362                 writew(U300_WDOG_FR_FEED_RESTART_TIMER,
 363                        virtbase + U300_WDOG_FR);
 364         }
 365         return 0;
 366 }
 367 #else
 368 #define coh901327_suspend NULL
 369 #define coh901327_resume  NULL
 370 #endif
 371
 372 /*
 373  * Mistreating the watchdog is the only way to perform a software reset of the
 374  * system on EMP platforms. So we implement this and export a symbol for it.
 375  */
 376 void coh901327_watchdog_reset(void)
 377 {
 378         /* Enable even if on JTAG too */
 379         writew(U300_WDOG_JOR_JTAG_WATCHDOG_ENABLE,
 380                virtbase + U300_WDOG_JOR);
 381         /*
 382          * Timeout = 5s, we have to wait for the watchdog reset to
 383          * actually take place: the watchdog will be reloaded with the
 384          * default value immediately, so we HAVE to reboot and get back
 385          * into the kernel in 30s, or the device will reboot again!
 386          * The boot loader will typically deactivate the watchdog, so we
 387          * need time enough for the boot loader to get to the point of
 388          * deactivating the watchdog before it is shut down by it.
 389          *
 390          * NOTE: on future versions of the watchdog, this restriction is
 391          * gone: the watchdog will be reloaded with a default value (1 min)
 392          * instead of last value, and you can conveniently set the watchdog
 393          * timeout to 10ms (value = 1) without any problems.
 394          */
 395         coh901327_enable(500);
 396         /* Return and await doom */
 397 }
 398
 399 static const struct of_device_id coh901327_dt_match[] = {
 400         { .compatible = "stericsson,coh901327" },
 401         {},
 402 };
 403
 404 static struct platform_driver coh901327_driver = {
 405         .driver = {
 406                 .name   = "coh901327_wdog",
 407                 .of_match_table = coh901327_dt_match,
 408         },
 409         .remove         = __exit_p(coh901327_remove),
 410         .suspend        = coh901327_suspend,
 411         .resume         = coh901327_resume,
 412 };
 413
 414 module_platform_driver_probe(coh901327_driver, coh901327_probe);
 415
 416 MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
 417 MODULE_DESCRIPTION("COH 901 327 Watchdog");
 418
 419 module_param(margin, uint, 0);
 420 MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");
 421
 422 MODULE_LICENSE("GPL");
 423 MODULE_ALIAS("platform:coh901327-watchdog");