drivers/watchdog/coh901327_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * coh901327_wdt.c
   4  *
   5  * Copyright (C) 2008-2009 ST-Ericsson AB
   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/moduleparam.h>
  10 #include <linux/mod_devicetable.h>
  11 #include <linux/types.h>
  12 #include <linux/watchdog.h>
  13 #include <linux/interrupt.h>
  14 #include <linux/pm.h>
  15 #include <linux/platform_device.h>
  16 #include <linux/io.h>
  17 #include <linux/bitops.h>
  18 #include <linux/clk.h>
  19 #include <linux/delay.h>
  20 #include <linux/err.h>
  21
  22 #define DRV_NAME "WDOG COH 901 327"
  23
  24 /*
  25  * COH 901 327 register definitions
  26  */
  27
  28 /* WDOG_FEED Register 32bit (-/W) */
  29 #define U300_WDOG_FR                                                    0x00
  30 #define U300_WDOG_FR_FEED_RESTART_TIMER                                 0xFEEDU
  31 /* WDOG_TIMEOUT Register 32bit (R/W) */
  32 #define U300_WDOG_TR                                                    0x04
  33 #define U300_WDOG_TR_TIMEOUT_MASK                                       0x7FFFU
  34 /* WDOG_DISABLE1 Register 32bit (-/W) */
  35 #define U300_WDOG_D1R                                                   0x08
  36 #define U300_WDOG_D1R_DISABLE1_DISABLE_TIMER                            0x2BADU
  37 /* WDOG_DISABLE2 Register 32bit (R/W) */
  38 #define U300_WDOG_D2R                                                   0x0C
  39 #define U300_WDOG_D2R_DISABLE2_DISABLE_TIMER                            0xCAFEU
  40 #define U300_WDOG_D2R_DISABLE_STATUS_DISABLED                           0xDABEU
  41 #define U300_WDOG_D2R_DISABLE_STATUS_ENABLED                            0x0000U
  42 /* WDOG_STATUS Register 32bit (R/W) */
  43 #define U300_WDOG_SR                                                    0x10
  44 #define U300_WDOG_SR_STATUS_TIMED_OUT                                   0xCFE8U
  45 #define U300_WDOG_SR_STATUS_NORMAL                                      0x0000U
  46 #define U300_WDOG_SR_RESET_STATUS_RESET                                 0xE8B4U
  47 /* WDOG_COUNT Register 32bit (R/-) */
  48 #define U300_WDOG_CR                                                    0x14
  49 #define U300_WDOG_CR_VALID_IND                                          0x8000U
  50 #define U300_WDOG_CR_VALID_STABLE                                       0x0000U
  51 #define U300_WDOG_CR_COUNT_VALUE_MASK                                   0x7FFFU
  52 /* WDOG_JTAGOVR Register 32bit (R/W) */
  53 #define U300_WDOG_JOR                                                   0x18
  54 #define U300_WDOG_JOR_JTAG_MODE_IND                                     0x0002U
  55 #define U300_WDOG_JOR_JTAG_WATCHDOG_ENABLE                              0x0001U
  56 /* WDOG_RESTART Register 32bit (-/W) */
  57 #define U300_WDOG_RR                                                    0x1C
  58 #define U300_WDOG_RR_RESTART_VALUE_RESUME                               0xACEDU
  59 /* WDOG_IRQ_EVENT Register 32bit (R/W) */
  60 #define U300_WDOG_IER                                                   0x20
  61 #define U300_WDOG_IER_WILL_BARK_IRQ_EVENT_IND                           0x0001U
  62 #define U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE                          0x0001U
  63 /* WDOG_IRQ_MASK Register 32bit (R/W) */
  64 #define U300_WDOG_IMR                                                   0x24
  65 #define U300_WDOG_IMR_WILL_BARK_IRQ_ENABLE                              0x0001U
  66 /* WDOG_IRQ_FORCE Register 32bit (R/W) */
  67 #define U300_WDOG_IFR                                                   0x28
  68 #define U300_WDOG_IFR_WILL_BARK_IRQ_FORCE_ENABLE                        0x0001U
  69
  70 /* Default timeout in seconds = 1 minute */
  71 #define U300_WDOG_DEFAULT_TIMEOUT                                       60
  72
  73 static unsigned int margin;
  74 static int irq;
  75 static void __iomem *virtbase;
  76 static struct device *parent;
  77
  78 static struct clk *clk;
  79
  80 /*
  81  * Enabling and disabling functions.
  82  */
  83 static void coh901327_enable(u16 timeout)
  84 {
  85         u16 val;
  86         unsigned long freq;
  87         unsigned long delay_ns;
  88
  89         /* Restart timer if it is disabled */
  90         val = readw(virtbase + U300_WDOG_D2R);
  91         if (val == U300_WDOG_D2R_DISABLE_STATUS_DISABLED)
  92                 writew(U300_WDOG_RR_RESTART_VALUE_RESUME,
  93                        virtbase + U300_WDOG_RR);
  94         /* Acknowledge any pending interrupt so it doesn't just fire off */
  95         writew(U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE,
  96                virtbase + U300_WDOG_IER);
  97         /*
  98          * The interrupt is cleared in the 32 kHz clock domain.
  99          * Wait 3 32 kHz cycles for it to take effect
 100          */
 101         freq = clk_get_rate(clk);
 102         delay_ns = DIV_ROUND_UP(1000000000, freq); /* Freq to ns and round up */
 103         delay_ns = 3 * delay_ns; /* Wait 3 cycles */
 104         ndelay(delay_ns);
 105         /* Enable the watchdog interrupt */
 106         writew(U300_WDOG_IMR_WILL_BARK_IRQ_ENABLE, virtbase + U300_WDOG_IMR);
 107         /* Activate the watchdog timer */
 108         writew(timeout, virtbase + U300_WDOG_TR);
 109         /* Start the watchdog timer */
 110         writew(U300_WDOG_FR_FEED_RESTART_TIMER, virtbase + U300_WDOG_FR);
 111         /*
 112          * Extra read so that this change propagate in the watchdog.
 113          */
 114         (void) readw(virtbase + U300_WDOG_CR);
 115         val = readw(virtbase + U300_WDOG_D2R);
 116         if (val != U300_WDOG_D2R_DISABLE_STATUS_ENABLED)
 117                 dev_err(parent,
 118                         "%s(): watchdog not enabled! D2R value %04x\n",
 119                         __func__, val);
 120 }
 121
 122 static void coh901327_disable(void)
 123 {
 124         u16 val;
 125
 126         /* Disable the watchdog interrupt if it is active */
 127         writew(0x0000U, virtbase + U300_WDOG_IMR);
 128         /* If the watchdog is currently enabled, attempt to disable it */
 129         val = readw(virtbase + U300_WDOG_D2R);
 130         if (val != U300_WDOG_D2R_DISABLE_STATUS_DISABLED) {
 131                 writew(U300_WDOG_D1R_DISABLE1_DISABLE_TIMER,
 132                        virtbase + U300_WDOG_D1R);
 133                 writew(U300_WDOG_D2R_DISABLE2_DISABLE_TIMER,
 134                        virtbase + U300_WDOG_D2R);
 135                 /* Write this twice (else problems occur) */
 136                 writew(U300_WDOG_D2R_DISABLE2_DISABLE_TIMER,
 137                        virtbase + U300_WDOG_D2R);
 138         }
 139         val = readw(virtbase + U300_WDOG_D2R);
 140         if (val != U300_WDOG_D2R_DISABLE_STATUS_DISABLED)
 141                 dev_err(parent,
 142                         "%s(): watchdog not disabled! D2R value %04x\n",
 143                         __func__, val);
 144 }
 145
 146 static int coh901327_start(struct watchdog_device *wdt_dev)
 147 {
 148         coh901327_enable(wdt_dev->timeout * 100);
 149         return 0;
 150 }
 151
 152 static int coh901327_stop(struct watchdog_device *wdt_dev)
 153 {
 154         coh901327_disable();
 155         return 0;
 156 }
 157
 158 static int coh901327_ping(struct watchdog_device *wdd)
 159 {
 160         /* Feed the watchdog */
 161         writew(U300_WDOG_FR_FEED_RESTART_TIMER,
 162                virtbase + U300_WDOG_FR);
 163         return 0;
 164 }
 165
 166 static int coh901327_settimeout(struct watchdog_device *wdt_dev,
 167                                 unsigned int time)
 168 {
 169         wdt_dev->timeout = time;
 170         /* Set new timeout value */
 171         writew(time * 100, virtbase + U300_WDOG_TR);
 172         /* Feed the dog */
 173         writew(U300_WDOG_FR_FEED_RESTART_TIMER,
 174                virtbase + U300_WDOG_FR);
 175         return 0;
 176 }
 177
 178 static unsigned int coh901327_gettimeleft(struct watchdog_device *wdt_dev)
 179 {
 180         u16 val;
 181
 182         /* Read repeatedly until the value is stable! */
 183         val = readw(virtbase + U300_WDOG_CR);
 184         while (val & U300_WDOG_CR_VALID_IND)
 185                 val = readw(virtbase + U300_WDOG_CR);
 186         val &= U300_WDOG_CR_COUNT_VALUE_MASK;
 187         if (val != 0)
 188                 val /= 100;
 189
 190         return val;
 191 }
 192
 193 /*
 194  * This interrupt occurs 10 ms before the watchdog WILL bark.
 195  */
 196 static irqreturn_t coh901327_interrupt(int irq, void *data)
 197 {
 198         u16 val;
 199
 200         /*
 201          * Ack IRQ? If this occurs we're FUBAR anyway, so
 202          * just acknowledge, disable the interrupt and await the imminent end.
 203          * If you at some point need a host of callbacks to be called
 204          * when the system is about to watchdog-reset, add them here!
 205          *
 206          * NOTE: on future versions of this IP-block, it will be possible
 207          * to prevent a watchdog reset by feeding the watchdog at this
 208          * point.
 209          */
 210         val = readw(virtbase + U300_WDOG_IER);
 211         if (val == U300_WDOG_IER_WILL_BARK_IRQ_EVENT_IND)
 212                 writew(U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE,
 213                        virtbase + U300_WDOG_IER);
 214         writew(0x0000U, virtbase + U300_WDOG_IMR);
 215         dev_crit(parent, "watchdog is barking!\n");
 216         return IRQ_HANDLED;
 217 }
 218
 219 static const struct watchdog_info coh901327_ident = {
 220         .options = WDIOF_CARDRESET | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 221         .identity = DRV_NAME,
 222 };
 223
 224 static const struct watchdog_ops coh901327_ops = {
 225         .owner = THIS_MODULE,
 226         .start = coh901327_start,
 227         .stop = coh901327_stop,
 228         .ping = coh901327_ping,
 229         .set_timeout = coh901327_settimeout,
 230         .get_timeleft = coh901327_gettimeleft,
 231 };
 232
 233 static struct watchdog_device coh901327_wdt = {
 234         .info = &coh901327_ident,
 235         .ops = &coh901327_ops,
 236         /*
 237          * Max timeout is 327 since the 10ms
 238          * timeout register is max
 239          * 0x7FFF = 327670ms ~= 327s.
 240          */
 241         .min_timeout = 1,
 242         .max_timeout = 327,
 243         .timeout = U300_WDOG_DEFAULT_TIMEOUT,
 244 };
 245
 246 static int __init coh901327_probe(struct platform_device *pdev)
 247 {
 248         struct device *dev = &pdev->dev;
 249         int ret;
 250         u16 val;
 251
 252         parent = dev;
 253
 254         virtbase = devm_platform_ioremap_resource(pdev, 0);
 255         if (IS_ERR(virtbase))
 256                 return PTR_ERR(virtbase);
 257
 258         clk = clk_get(dev, NULL);
 259         if (IS_ERR(clk)) {
 260                 ret = PTR_ERR(clk);
 261                 dev_err(dev, "could not get clock\n");
 262                 return ret;
 263         }
 264         ret = clk_prepare_enable(clk);
 265         if (ret) {
 266                 dev_err(dev, "could not prepare and enable clock\n");
 267                 goto out_no_clk_enable;
 268         }
 269
 270         val = readw(virtbase + U300_WDOG_SR);
 271         switch (val) {
 272         case U300_WDOG_SR_STATUS_TIMED_OUT:
 273                 dev_info(dev, "watchdog timed out since last chip reset!\n");
 274                 coh901327_wdt.bootstatus |= WDIOF_CARDRESET;
 275                 /* Status will be cleared below */
 276                 break;
 277         case U300_WDOG_SR_STATUS_NORMAL:
 278                 dev_info(dev, "in normal status, no timeouts have occurred.\n");
 279                 break;
 280         default:
 281                 dev_info(dev, "contains an illegal status code (%08x)\n", val);
 282                 break;
 283         }
 284
 285         val = readw(virtbase + U300_WDOG_D2R);
 286         switch (val) {
 287         case U300_WDOG_D2R_DISABLE_STATUS_DISABLED:
 288                 dev_info(dev, "currently disabled.\n");
 289                 break;
 290         case U300_WDOG_D2R_DISABLE_STATUS_ENABLED:
 291                 dev_info(dev, "currently enabled! (disabling it now)\n");
 292                 coh901327_disable();
 293                 break;
 294         default:
 295                 dev_err(dev, "contains an illegal enable/disable code (%08x)\n",
 296                         val);
 297                 break;
 298         }
 299
 300         /* Reset the watchdog */
 301         writew(U300_WDOG_SR_RESET_STATUS_RESET, virtbase + U300_WDOG_SR);
 302
 303         irq = platform_get_irq(pdev, 0);
 304         if (request_irq(irq, coh901327_interrupt, 0,
 305                         DRV_NAME " Bark", pdev)) {
 306                 ret = -EIO;
 307                 goto out_no_irq;
 308         }
 309
 310         watchdog_init_timeout(&coh901327_wdt, margin, dev);
 311
 312         coh901327_wdt.parent = dev;
 313         ret = watchdog_register_device(&coh901327_wdt);
 314         if (ret)
 315                 goto out_no_wdog;
 316
 317         dev_info(dev, "initialized. (timeout=%d sec)\n",
 318                         coh901327_wdt.timeout);
 319         return 0;
 320
 321 out_no_wdog:
 322         free_irq(irq, pdev);
 323 out_no_irq:
 324         clk_disable_unprepare(clk);
 325 out_no_clk_enable:
 326         clk_put(clk);
 327         return ret;
 328 }
 329
 330 #ifdef CONFIG_PM
 331
 332 static u16 wdogenablestore;
 333 static u16 irqmaskstore;
 334
 335 static int coh901327_suspend(struct platform_device *pdev, pm_message_t state)
 336 {
 337         irqmaskstore = readw(virtbase + U300_WDOG_IMR) & 0x0001U;
 338         wdogenablestore = readw(virtbase + U300_WDOG_D2R);
 339         /* If watchdog is on, disable it here and now */
 340         if (wdogenablestore == U300_WDOG_D2R_DISABLE_STATUS_ENABLED)
 341                 coh901327_disable();
 342         return 0;
 343 }
 344
 345 static int coh901327_resume(struct platform_device *pdev)
 346 {
 347         /* Restore the watchdog interrupt */
 348         writew(irqmaskstore, virtbase + U300_WDOG_IMR);
 349         if (wdogenablestore == U300_WDOG_D2R_DISABLE_STATUS_ENABLED) {
 350                 /* Restart the watchdog timer */
 351                 writew(U300_WDOG_RR_RESTART_VALUE_RESUME,
 352                        virtbase + U300_WDOG_RR);
 353                 writew(U300_WDOG_FR_FEED_RESTART_TIMER,
 354                        virtbase + U300_WDOG_FR);
 355         }
 356         return 0;
 357 }
 358 #else
 359 #define coh901327_suspend NULL
 360 #define coh901327_resume  NULL
 361 #endif
 362
 363 /*
 364  * Mistreating the watchdog is the only way to perform a software reset of the
 365  * system on EMP platforms. So we implement this and export a symbol for it.
 366  */
 367 void coh901327_watchdog_reset(void)
 368 {
 369         /* Enable even if on JTAG too */
 370         writew(U300_WDOG_JOR_JTAG_WATCHDOG_ENABLE,
 371                virtbase + U300_WDOG_JOR);
 372         /*
 373          * Timeout = 5s, we have to wait for the watchdog reset to
 374          * actually take place: the watchdog will be reloaded with the
 375          * default value immediately, so we HAVE to reboot and get back
 376          * into the kernel in 30s, or the device will reboot again!
 377          * The boot loader will typically deactivate the watchdog, so we
 378          * need time enough for the boot loader to get to the point of
 379          * deactivating the watchdog before it is shut down by it.
 380          *
 381          * NOTE: on future versions of the watchdog, this restriction is
 382          * gone: the watchdog will be reloaded with a default value (1 min)
 383          * instead of last value, and you can conveniently set the watchdog
 384          * timeout to 10ms (value = 1) without any problems.
 385          */
 386         coh901327_enable(500);
 387         /* Return and await doom */
 388 }
 389
 390 static const struct of_device_id coh901327_dt_match[] = {
 391         { .compatible = "stericsson,coh901327" },
 392         {},
 393 };
 394
 395 static struct platform_driver coh901327_driver = {
 396         .driver = {
 397                 .name   = "coh901327_wdog",
 398                 .of_match_table = coh901327_dt_match,
 399                 .suppress_bind_attrs = true,
 400         },
 401         .suspend        = coh901327_suspend,
 402         .resume         = coh901327_resume,
 403 };
 404 builtin_platform_driver_probe(coh901327_driver, coh901327_probe);
 405
 406 /* not really modular, but ... */
 407 module_param(margin, uint, 0);
 408 MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");