drivers/watchdog/imx2_wdt.c

   1 /*
   2  * Watchdog driver for IMX2 and later processors
   3  *
   4  *  Copyright (C) 2010 Wolfram Sang, Pengutronix e.K. <w.sang@pengutronix.de>
   5  *  Copyright (C) 2014 Freescale Semiconductor, Inc.
   6  *
   7  * some parts adapted by similar drivers from Darius Augulis and Vladimir
   8  * Zapolskiy, additional improvements by Wim Van Sebroeck.
   9  *
  10  * This program is free software; you can redistribute it and/or modify it
  11  * under the terms of the GNU General Public License version 2 as published by
  12  * the Free Software Foundation.
  13  *
  14  * NOTE: MX1 has a slightly different Watchdog than MX2 and later:
  15  *
  16  *                      MX1:            MX2+:
  17  *                      ----            -----
  18  * Registers:           32-bit          16-bit
  19  * Stopable timer:      Yes             No
  20  * Need to enable clk:  No              Yes
  21  * Halt on suspend:     Manual          Can be automatic
  22  */
  23
  24 #include <linux/clk.h>
  25 #include <linux/delay.h>
  26 #include <linux/init.h>
  27 #include <linux/io.h>
  28 #include <linux/jiffies.h>
  29 #include <linux/kernel.h>
  30 #include <linux/module.h>
  31 #include <linux/moduleparam.h>
  32 #include <linux/notifier.h>
  33 #include <linux/of_address.h>
  34 #include <linux/platform_device.h>
  35 #include <linux/reboot.h>
  36 #include <linux/regmap.h>
  37 #include <linux/timer.h>
  38 #include <linux/watchdog.h>
  39
  40 #define DRIVER_NAME "imx2-wdt"
  41
  42 #define IMX2_WDT_WCR            0x00            /* Control Register */
  43 #define IMX2_WDT_WCR_WT         (0xFF << 8)     /* -> Watchdog Timeout Field */
  44 #define IMX2_WDT_WCR_WRE        (1 << 3)        /* -> WDOG Reset Enable */
  45 #define IMX2_WDT_WCR_WDE        (1 << 2)        /* -> Watchdog Enable */
  46 #define IMX2_WDT_WCR_WDZST      (1 << 0)        /* -> Watchdog timer Suspend */
  47
  48 #define IMX2_WDT_WSR            0x02            /* Service Register */
  49 #define IMX2_WDT_SEQ1           0x5555          /* -> service sequence 1 */
  50 #define IMX2_WDT_SEQ2           0xAAAA          /* -> service sequence 2 */
  51
  52 #define IMX2_WDT_WRSR           0x04            /* Reset Status Register */
  53 #define IMX2_WDT_WRSR_TOUT      (1 << 1)        /* -> Reset due to Timeout */
  54
  55 #define IMX2_WDT_WMCR           0x08            /* Misc Register */
  56
  57 #define IMX2_WDT_MAX_TIME       128
  58 #define IMX2_WDT_DEFAULT_TIME   60              /* in seconds */
  59
  60 #define WDOG_SEC_TO_COUNT(s)    ((s * 2 - 1) << 8)
  61
  62 struct imx2_wdt_device {
  63         struct clk *clk;
  64         struct regmap *regmap;
  65         struct timer_list timer;        /* Pings the watchdog when closed */
  66         struct watchdog_device wdog;
  67         struct notifier_block restart_handler;
  68 };
  69
  70 static bool nowayout = WATCHDOG_NOWAYOUT;
  71 module_param(nowayout, bool, 0);
  72 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  73                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  74
  75
  76 static unsigned timeout = IMX2_WDT_DEFAULT_TIME;
  77 module_param(timeout, uint, 0);
  78 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
  79                                 __MODULE_STRING(IMX2_WDT_DEFAULT_TIME) ")");
  80
  81 static const struct watchdog_info imx2_wdt_info = {
  82         .identity = "imx2+ watchdog",
  83         .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
  84 };
  85
  86 static int imx2_restart_handler(struct notifier_block *this, unsigned long mode,
  87                                 void *cmd)
  88 {
  89         unsigned int wcr_enable = IMX2_WDT_WCR_WDE;
  90         struct imx2_wdt_device *wdev = container_of(this,
  91                                                     struct imx2_wdt_device,
  92                                                     restart_handler);
  93         /* Assert SRS signal */
  94         regmap_write(wdev->regmap, IMX2_WDT_WCR, wcr_enable);
  95         /*
  96          * Due to imx6q errata ERR004346 (WDOG: WDOG SRS bit requires to be
  97          * written twice), we add another two writes to ensure there must be at
  98          * least two writes happen in the same one 32kHz clock period.  We save
  99          * the target check here, since the writes shouldn't be a huge burden
 100          * for other platforms.
 101          */
 102         regmap_write(wdev->regmap, IMX2_WDT_WCR, wcr_enable);
 103         regmap_write(wdev->regmap, IMX2_WDT_WCR, wcr_enable);
 104
 105         /* wait for reset to assert... */
 106         mdelay(500);
 107
 108         return NOTIFY_DONE;
 109 }
 110
 111 static inline void imx2_wdt_setup(struct watchdog_device *wdog)
 112 {
 113         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 114         u32 val;
 115
 116         regmap_read(wdev->regmap, IMX2_WDT_WCR, &val);
 117
 118         /* Suspend timer in low power mode, write once-only */
 119         val |= IMX2_WDT_WCR_WDZST;
 120         /* Strip the old watchdog Time-Out value */
 121         val &= ~IMX2_WDT_WCR_WT;
 122         /* Generate reset if WDOG times out */
 123         val &= ~IMX2_WDT_WCR_WRE;
 124         /* Keep Watchdog Disabled */
 125         val &= ~IMX2_WDT_WCR_WDE;
 126         /* Set the watchdog's Time-Out value */
 127         val |= WDOG_SEC_TO_COUNT(wdog->timeout);
 128
 129         regmap_write(wdev->regmap, IMX2_WDT_WCR, val);
 130
 131         /* enable the watchdog */
 132         val |= IMX2_WDT_WCR_WDE;
 133         regmap_write(wdev->regmap, IMX2_WDT_WCR, val);
 134 }
 135
 136 static inline bool imx2_wdt_is_running(struct imx2_wdt_device *wdev)
 137 {
 138         u32 val;
 139
 140         regmap_read(wdev->regmap, IMX2_WDT_WCR, &val);
 141
 142         return val & IMX2_WDT_WCR_WDE;
 143 }
 144
 145 static int imx2_wdt_ping(struct watchdog_device *wdog)
 146 {
 147         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 148
 149         regmap_write(wdev->regmap, IMX2_WDT_WSR, IMX2_WDT_SEQ1);
 150         regmap_write(wdev->regmap, IMX2_WDT_WSR, IMX2_WDT_SEQ2);
 151         return 0;
 152 }
 153
 154 static void imx2_wdt_timer_ping(unsigned long arg)
 155 {
 156         struct watchdog_device *wdog = (struct watchdog_device *)arg;
 157         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 158
 159         /* ping it every wdog->timeout / 2 seconds to prevent reboot */
 160         imx2_wdt_ping(wdog);
 161         mod_timer(&wdev->timer, jiffies + wdog->timeout * HZ / 2);
 162 }
 163
 164 static int imx2_wdt_set_timeout(struct watchdog_device *wdog,
 165                                 unsigned int new_timeout)
 166 {
 167         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 168
 169         wdog->timeout = new_timeout;
 170
 171         regmap_update_bits(wdev->regmap, IMX2_WDT_WCR, IMX2_WDT_WCR_WT,
 172                            WDOG_SEC_TO_COUNT(new_timeout));
 173         return 0;
 174 }
 175
 176 static int imx2_wdt_start(struct watchdog_device *wdog)
 177 {
 178         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 179
 180         if (imx2_wdt_is_running(wdev)) {
 181                 /* delete the timer that pings the watchdog after close */
 182                 del_timer_sync(&wdev->timer);
 183                 imx2_wdt_set_timeout(wdog, wdog->timeout);
 184         } else
 185                 imx2_wdt_setup(wdog);
 186
 187         return imx2_wdt_ping(wdog);
 188 }
 189
 190 static int imx2_wdt_stop(struct watchdog_device *wdog)
 191 {
 192         /*
 193          * We don't need a clk_disable, it cannot be disabled once started.
 194          * We use a timer to ping the watchdog while /dev/watchdog is closed
 195          */
 196         imx2_wdt_timer_ping((unsigned long)wdog);
 197         return 0;
 198 }
 199
 200 static inline void imx2_wdt_ping_if_active(struct watchdog_device *wdog)
 201 {
 202         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 203
 204         if (imx2_wdt_is_running(wdev)) {
 205                 imx2_wdt_set_timeout(wdog, wdog->timeout);
 206                 imx2_wdt_timer_ping((unsigned long)wdog);
 207         }
 208 }
 209
 210 static const struct watchdog_ops imx2_wdt_ops = {
 211         .owner = THIS_MODULE,
 212         .start = imx2_wdt_start,
 213         .stop = imx2_wdt_stop,
 214         .ping = imx2_wdt_ping,
 215         .set_timeout = imx2_wdt_set_timeout,
 216 };
 217
 218 static const struct regmap_config imx2_wdt_regmap_config = {
 219         .reg_bits = 16,
 220         .reg_stride = 2,
 221         .val_bits = 16,
 222         .max_register = 0x8,
 223 };
 224
 225 static int __init imx2_wdt_probe(struct platform_device *pdev)
 226 {
 227         struct imx2_wdt_device *wdev;
 228         struct watchdog_device *wdog;
 229         struct resource *res;
 230         void __iomem *base;
 231         int ret;
 232         u32 val;
 233
 234         wdev = devm_kzalloc(&pdev->dev, sizeof(*wdev), GFP_KERNEL);
 235         if (!wdev)
 236                 return -ENOMEM;
 237
 238         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 239         base = devm_ioremap_resource(&pdev->dev, res);
 240         if (IS_ERR(base))
 241                 return PTR_ERR(base);
 242
 243         wdev->regmap = devm_regmap_init_mmio_clk(&pdev->dev, NULL, base,
 244                                                  &imx2_wdt_regmap_config);
 245         if (IS_ERR(wdev->regmap)) {
 246                 dev_err(&pdev->dev, "regmap init failed\n");
 247                 return PTR_ERR(wdev->regmap);
 248         }
 249
 250         wdev->clk = devm_clk_get(&pdev->dev, NULL);
 251         if (IS_ERR(wdev->clk)) {
 252                 dev_err(&pdev->dev, "can't get Watchdog clock\n");
 253                 return PTR_ERR(wdev->clk);
 254         }
 255
 256         wdog                    = &wdev->wdog;
 257         wdog->info              = &imx2_wdt_info;
 258         wdog->ops               = &imx2_wdt_ops;
 259         wdog->min_timeout       = 1;
 260         wdog->max_timeout       = IMX2_WDT_MAX_TIME;
 261         wdog->parent            = &pdev->dev;
 262
 263         ret = clk_prepare_enable(wdev->clk);
 264         if (ret)
 265                 return ret;
 266
 267         regmap_read(wdev->regmap, IMX2_WDT_WRSR, &val);
 268         wdog->bootstatus = val & IMX2_WDT_WRSR_TOUT ? WDIOF_CARDRESET : 0;
 269
 270         wdog->timeout = clamp_t(unsigned, timeout, 1, IMX2_WDT_MAX_TIME);
 271         if (wdog->timeout != timeout)
 272                 dev_warn(&pdev->dev, "Initial timeout out of range! Clamped from %u to %u\n",
 273                          timeout, wdog->timeout);
 274
 275         platform_set_drvdata(pdev, wdog);
 276         watchdog_set_drvdata(wdog, wdev);
 277         watchdog_set_nowayout(wdog, nowayout);
 278         watchdog_init_timeout(wdog, timeout, &pdev->dev);
 279
 280         setup_timer(&wdev->timer, imx2_wdt_timer_ping, (unsigned long)wdog);
 281
 282         imx2_wdt_ping_if_active(wdog);
 283
 284         /*
 285          * Disable the watchdog power down counter at boot. Otherwise the power
 286          * down counter will pull down the #WDOG interrupt line for one clock
 287          * cycle.
 288          */
 289         regmap_write(wdev->regmap, IMX2_WDT_WMCR, 0);
 290
 291         ret = watchdog_register_device(wdog);
 292         if (ret) {
 293                 dev_err(&pdev->dev, "cannot register watchdog device\n");
 294                 goto disable_clk;
 295         }
 296
 297         wdev->restart_handler.notifier_call = imx2_restart_handler;
 298         wdev->restart_handler.priority = 128;
 299         ret = register_restart_handler(&wdev->restart_handler);
 300         if (ret)
 301                 dev_err(&pdev->dev, "cannot register restart handler\n");
 302
 303         dev_info(&pdev->dev, "timeout %d sec (nowayout=%d)\n",
 304                  wdog->timeout, nowayout);
 305
 306         return 0;
 307
 308 disable_clk:
 309         clk_disable_unprepare(wdev->clk);
 310         return ret;
 311 }
 312
 313 static int __exit imx2_wdt_remove(struct platform_device *pdev)
 314 {
 315         struct watchdog_device *wdog = platform_get_drvdata(pdev);
 316         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 317
 318         unregister_restart_handler(&wdev->restart_handler);
 319
 320         watchdog_unregister_device(wdog);
 321
 322         if (imx2_wdt_is_running(wdev)) {
 323                 del_timer_sync(&wdev->timer);
 324                 imx2_wdt_ping(wdog);
 325                 dev_crit(&pdev->dev, "Device removed: Expect reboot!\n");
 326         }
 327         return 0;
 328 }
 329
 330 static void imx2_wdt_shutdown(struct platform_device *pdev)
 331 {
 332         struct watchdog_device *wdog = platform_get_drvdata(pdev);
 333         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 334
 335         if (imx2_wdt_is_running(wdev)) {
 336                 /*
 337                  * We are running, we need to delete the timer but will
 338                  * give max timeout before reboot will take place
 339                  */
 340                 del_timer_sync(&wdev->timer);
 341                 imx2_wdt_set_timeout(wdog, IMX2_WDT_MAX_TIME);
 342                 imx2_wdt_ping(wdog);
 343                 dev_crit(&pdev->dev, "Device shutdown: Expect reboot!\n");
 344         }
 345 }
 346
 347 #ifdef CONFIG_PM_SLEEP
 348 /* Disable watchdog if it is active or non-active but still running */
 349 static int imx2_wdt_suspend(struct device *dev)
 350 {
 351         struct watchdog_device *wdog = dev_get_drvdata(dev);
 352         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 353
 354         /* The watchdog IP block is running */
 355         if (imx2_wdt_is_running(wdev)) {
 356                 imx2_wdt_set_timeout(wdog, IMX2_WDT_MAX_TIME);
 357                 imx2_wdt_ping(wdog);
 358
 359                 /* The watchdog is not active */
 360                 if (!watchdog_active(wdog))
 361                         del_timer_sync(&wdev->timer);
 362         }
 363
 364         clk_disable_unprepare(wdev->clk);
 365
 366         return 0;
 367 }
 368
 369 /* Enable watchdog and configure it if necessary */
 370 static int imx2_wdt_resume(struct device *dev)
 371 {
 372         struct watchdog_device *wdog = dev_get_drvdata(dev);
 373         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 374         int ret;
 375
 376         ret = clk_prepare_enable(wdev->clk);
 377         if (ret)
 378                 return ret;
 379
 380         if (watchdog_active(wdog) && !imx2_wdt_is_running(wdev)) {
 381                 /*
 382                  * If the watchdog is still active and resumes
 383                  * from deep sleep state, need to restart the
 384                  * watchdog again.
 385                  */
 386                 imx2_wdt_setup(wdog);
 387                 imx2_wdt_set_timeout(wdog, wdog->timeout);
 388                 imx2_wdt_ping(wdog);
 389         } else if (imx2_wdt_is_running(wdev)) {
 390                 /* Resuming from non-deep sleep state. */
 391                 imx2_wdt_set_timeout(wdog, wdog->timeout);
 392                 imx2_wdt_ping(wdog);
 393                 /*
 394                  * But the watchdog is not active, then start
 395                  * the timer again.
 396                  */
 397                 if (!watchdog_active(wdog))
 398                         mod_timer(&wdev->timer,
 399                                   jiffies + wdog->timeout * HZ / 2);
 400         }
 401
 402         return 0;
 403 }
 404 #endif
 405
 406 static SIMPLE_DEV_PM_OPS(imx2_wdt_pm_ops, imx2_wdt_suspend,
 407                          imx2_wdt_resume);
 408
 409 static const struct of_device_id imx2_wdt_dt_ids[] = {
 410         { .compatible = "fsl,imx21-wdt", },
 411         { /* sentinel */ }
 412 };
 413 MODULE_DEVICE_TABLE(of, imx2_wdt_dt_ids);
 414
 415 static struct platform_driver imx2_wdt_driver = {
 416         .remove         = __exit_p(imx2_wdt_remove),
 417         .shutdown       = imx2_wdt_shutdown,
 418         .driver         = {
 419                 .name   = DRIVER_NAME,
 420                 .pm     = &imx2_wdt_pm_ops,
 421                 .of_match_table = imx2_wdt_dt_ids,
 422         },
 423 };
 424
 425 module_platform_driver_probe(imx2_wdt_driver, imx2_wdt_probe);
 426
 427 MODULE_AUTHOR("Wolfram Sang");
 428 MODULE_DESCRIPTION("Watchdog driver for IMX2 and later");
 429 MODULE_LICENSE("GPL v2");
 430 MODULE_ALIAS("platform:" DRIVER_NAME);