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_MAX_TIME       128
  56 #define IMX2_WDT_DEFAULT_TIME   60              /* in seconds */
  57
  58 #define WDOG_SEC_TO_COUNT(s)    ((s * 2 - 1) << 8)
  59
  60 struct imx2_wdt_device {
  61         struct clk *clk;
  62         struct regmap *regmap;
  63         struct timer_list timer;        /* Pings the watchdog when closed */
  64         struct watchdog_device wdog;
  65         struct notifier_block restart_handler;
  66 };
  67
  68 static bool nowayout = WATCHDOG_NOWAYOUT;
  69 module_param(nowayout, bool, 0);
  70 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  71                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  72
  73
  74 static unsigned timeout = IMX2_WDT_DEFAULT_TIME;
  75 module_param(timeout, uint, 0);
  76 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
  77                                 __MODULE_STRING(IMX2_WDT_DEFAULT_TIME) ")");
  78
  79 static const struct watchdog_info imx2_wdt_info = {
  80         .identity = "imx2+ watchdog",
  81         .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
  82 };
  83
  84 static int imx2_restart_handler(struct notifier_block *this, unsigned long mode,
  85                                 void *cmd)
  86 {
  87         unsigned int wcr_enable = IMX2_WDT_WCR_WDE;
  88         struct imx2_wdt_device *wdev = container_of(this,
  89                                                     struct imx2_wdt_device,
  90                                                     restart_handler);
  91         /* Assert SRS signal */
  92         regmap_write(wdev->regmap, 0, wcr_enable);
  93         /*
  94          * Due to imx6q errata ERR004346 (WDOG: WDOG SRS bit requires to be
  95          * written twice), we add another two writes to ensure there must be at
  96          * least two writes happen in the same one 32kHz clock period.  We save
  97          * the target check here, since the writes shouldn't be a huge burden
  98          * for other platforms.
  99          */
 100         regmap_write(wdev->regmap, 0, wcr_enable);
 101         regmap_write(wdev->regmap, 0, wcr_enable);
 102
 103         /* wait for reset to assert... */
 104         mdelay(500);
 105
 106         return NOTIFY_DONE;
 107 }
 108
 109 static inline void imx2_wdt_setup(struct watchdog_device *wdog)
 110 {
 111         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 112         u32 val;
 113
 114         regmap_read(wdev->regmap, IMX2_WDT_WCR, &val);
 115
 116         /* Suspend timer in low power mode, write once-only */
 117         val |= IMX2_WDT_WCR_WDZST;
 118         /* Strip the old watchdog Time-Out value */
 119         val &= ~IMX2_WDT_WCR_WT;
 120         /* Generate reset if WDOG times out */
 121         val &= ~IMX2_WDT_WCR_WRE;
 122         /* Keep Watchdog Disabled */
 123         val &= ~IMX2_WDT_WCR_WDE;
 124         /* Set the watchdog's Time-Out value */
 125         val |= WDOG_SEC_TO_COUNT(wdog->timeout);
 126
 127         regmap_write(wdev->regmap, IMX2_WDT_WCR, val);
 128
 129         /* enable the watchdog */
 130         val |= IMX2_WDT_WCR_WDE;
 131         regmap_write(wdev->regmap, IMX2_WDT_WCR, val);
 132 }
 133
 134 static inline bool imx2_wdt_is_running(struct imx2_wdt_device *wdev)
 135 {
 136         u32 val;
 137
 138         regmap_read(wdev->regmap, IMX2_WDT_WCR, &val);
 139
 140         return val & IMX2_WDT_WCR_WDE;
 141 }
 142
 143 static int imx2_wdt_ping(struct watchdog_device *wdog)
 144 {
 145         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 146
 147         regmap_write(wdev->regmap, IMX2_WDT_WSR, IMX2_WDT_SEQ1);
 148         regmap_write(wdev->regmap, IMX2_WDT_WSR, IMX2_WDT_SEQ2);
 149         return 0;
 150 }
 151
 152 static void imx2_wdt_timer_ping(unsigned long arg)
 153 {
 154         struct watchdog_device *wdog = (struct watchdog_device *)arg;
 155         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 156
 157         /* ping it every wdog->timeout / 2 seconds to prevent reboot */
 158         imx2_wdt_ping(wdog);
 159         mod_timer(&wdev->timer, jiffies + wdog->timeout * HZ / 2);
 160 }
 161
 162 static int imx2_wdt_set_timeout(struct watchdog_device *wdog,
 163                                 unsigned int new_timeout)
 164 {
 165         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 166
 167         regmap_update_bits(wdev->regmap, IMX2_WDT_WCR, IMX2_WDT_WCR_WT,
 168                            WDOG_SEC_TO_COUNT(new_timeout));
 169         return 0;
 170 }
 171
 172 static int imx2_wdt_start(struct watchdog_device *wdog)
 173 {
 174         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 175
 176         if (imx2_wdt_is_running(wdev)) {
 177                 /* delete the timer that pings the watchdog after close */
 178                 del_timer_sync(&wdev->timer);
 179                 imx2_wdt_set_timeout(wdog, wdog->timeout);
 180         } else
 181                 imx2_wdt_setup(wdog);
 182
 183         return imx2_wdt_ping(wdog);
 184 }
 185
 186 static int imx2_wdt_stop(struct watchdog_device *wdog)
 187 {
 188         /*
 189          * We don't need a clk_disable, it cannot be disabled once started.
 190          * We use a timer to ping the watchdog while /dev/watchdog is closed
 191          */
 192         imx2_wdt_timer_ping((unsigned long)wdog);
 193         return 0;
 194 }
 195
 196 static inline void imx2_wdt_ping_if_active(struct watchdog_device *wdog)
 197 {
 198         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 199
 200         if (imx2_wdt_is_running(wdev)) {
 201                 imx2_wdt_set_timeout(wdog, wdog->timeout);
 202                 imx2_wdt_timer_ping((unsigned long)wdog);
 203         }
 204 }
 205
 206 static struct watchdog_ops imx2_wdt_ops = {
 207         .owner = THIS_MODULE,
 208         .start = imx2_wdt_start,
 209         .stop = imx2_wdt_stop,
 210         .ping = imx2_wdt_ping,
 211         .set_timeout = imx2_wdt_set_timeout,
 212 };
 213
 214 static struct regmap_config imx2_wdt_regmap_config = {
 215         .reg_bits = 16,
 216         .reg_stride = 2,
 217         .val_bits = 16,
 218         .max_register = 0x8,
 219 };
 220
 221 static int __init imx2_wdt_probe(struct platform_device *pdev)
 222 {
 223         struct imx2_wdt_device *wdev;
 224         struct watchdog_device *wdog;
 225         struct resource *res;
 226         void __iomem *base;
 227         int ret;
 228         u32 val;
 229
 230         wdev = devm_kzalloc(&pdev->dev, sizeof(*wdev), GFP_KERNEL);
 231         if (!wdev)
 232                 return -ENOMEM;
 233
 234         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 235         base = devm_ioremap_resource(&pdev->dev, res);
 236         if (IS_ERR(base))
 237                 return PTR_ERR(base);
 238
 239         wdev->regmap = devm_regmap_init_mmio_clk(&pdev->dev, NULL, base,
 240                                                  &imx2_wdt_regmap_config);
 241         if (IS_ERR(wdev->regmap)) {
 242                 dev_err(&pdev->dev, "regmap init failed\n");
 243                 return PTR_ERR(wdev->regmap);
 244         }
 245
 246         wdev->clk = devm_clk_get(&pdev->dev, NULL);
 247         if (IS_ERR(wdev->clk)) {
 248                 dev_err(&pdev->dev, "can't get Watchdog clock\n");
 249                 return PTR_ERR(wdev->clk);
 250         }
 251
 252         wdog                    = &wdev->wdog;
 253         wdog->info              = &imx2_wdt_info;
 254         wdog->ops               = &imx2_wdt_ops;
 255         wdog->min_timeout       = 1;
 256         wdog->max_timeout       = IMX2_WDT_MAX_TIME;
 257
 258         clk_prepare_enable(wdev->clk);
 259
 260         regmap_read(wdev->regmap, IMX2_WDT_WRSR, &val);
 261         wdog->bootstatus = val & IMX2_WDT_WRSR_TOUT ? WDIOF_CARDRESET : 0;
 262
 263         wdog->timeout = clamp_t(unsigned, timeout, 1, IMX2_WDT_MAX_TIME);
 264         if (wdog->timeout != timeout)
 265                 dev_warn(&pdev->dev, "Initial timeout out of range! Clamped from %u to %u\n",
 266                          timeout, wdog->timeout);
 267
 268         platform_set_drvdata(pdev, wdog);
 269         watchdog_set_drvdata(wdog, wdev);
 270         watchdog_set_nowayout(wdog, nowayout);
 271         watchdog_init_timeout(wdog, timeout, &pdev->dev);
 272
 273         setup_timer(&wdev->timer, imx2_wdt_timer_ping, (unsigned long)wdog);
 274
 275         imx2_wdt_ping_if_active(wdog);
 276
 277         ret = watchdog_register_device(wdog);
 278         if (ret) {
 279                 dev_err(&pdev->dev, "cannot register watchdog device\n");
 280                 return ret;
 281         }
 282
 283         wdev->restart_handler.notifier_call = imx2_restart_handler;
 284         wdev->restart_handler.priority = 128;
 285         ret = register_restart_handler(&wdev->restart_handler);
 286         if (ret)
 287                 dev_err(&pdev->dev, "cannot register restart handler\n");
 288
 289         dev_info(&pdev->dev, "timeout %d sec (nowayout=%d)\n",
 290                  wdog->timeout, nowayout);
 291
 292         return 0;
 293 }
 294
 295 static int __exit imx2_wdt_remove(struct platform_device *pdev)
 296 {
 297         struct watchdog_device *wdog = platform_get_drvdata(pdev);
 298         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 299
 300         unregister_restart_handler(&wdev->restart_handler);
 301
 302         watchdog_unregister_device(wdog);
 303
 304         if (imx2_wdt_is_running(wdev)) {
 305                 del_timer_sync(&wdev->timer);
 306                 imx2_wdt_ping(wdog);
 307                 dev_crit(&pdev->dev, "Device removed: Expect reboot!\n");
 308         }
 309         return 0;
 310 }
 311
 312 static void imx2_wdt_shutdown(struct platform_device *pdev)
 313 {
 314         struct watchdog_device *wdog = platform_get_drvdata(pdev);
 315         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 316
 317         if (imx2_wdt_is_running(wdev)) {
 318                 /*
 319                  * We are running, we need to delete the timer but will
 320                  * give max timeout before reboot will take place
 321                  */
 322                 del_timer_sync(&wdev->timer);
 323                 imx2_wdt_set_timeout(wdog, IMX2_WDT_MAX_TIME);
 324                 imx2_wdt_ping(wdog);
 325                 dev_crit(&pdev->dev, "Device shutdown: Expect reboot!\n");
 326         }
 327 }
 328
 329 static const struct of_device_id imx2_wdt_dt_ids[] = {
 330         { .compatible = "fsl,imx21-wdt", },
 331         { /* sentinel */ }
 332 };
 333 MODULE_DEVICE_TABLE(of, imx2_wdt_dt_ids);
 334
 335 static struct platform_driver imx2_wdt_driver = {
 336         .remove         = __exit_p(imx2_wdt_remove),
 337         .shutdown       = imx2_wdt_shutdown,
 338         .driver         = {
 339                 .name   = DRIVER_NAME,
 340                 .of_match_table = imx2_wdt_dt_ids,
 341         },
 342 };
 343
 344 module_platform_driver_probe(imx2_wdt_driver, imx2_wdt_probe);
 345
 346 MODULE_AUTHOR("Wolfram Sang");
 347 MODULE_DESCRIPTION("Watchdog driver for IMX2 and later");
 348 MODULE_LICENSE("GPL v2");
 349 MODULE_ALIAS("platform:" DRIVER_NAME);