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/init.h>
  26 #include <linux/io.h>
  27 #include <linux/jiffies.h>
  28 #include <linux/kernel.h>
  29 #include <linux/module.h>
  30 #include <linux/moduleparam.h>
  31 #include <linux/platform_device.h>
  32 #include <linux/regmap.h>
  33 #include <linux/timer.h>
  34 #include <linux/watchdog.h>
  35
  36 #define DRIVER_NAME "imx2-wdt"
  37
  38 #define IMX2_WDT_WCR            0x00            /* Control Register */
  39 #define IMX2_WDT_WCR_WT         (0xFF << 8)     /* -> Watchdog Timeout Field */
  40 #define IMX2_WDT_WCR_WRE        (1 << 3)        /* -> WDOG Reset Enable */
  41 #define IMX2_WDT_WCR_WDE        (1 << 2)        /* -> Watchdog Enable */
  42 #define IMX2_WDT_WCR_WDZST      (1 << 0)        /* -> Watchdog timer Suspend */
  43
  44 #define IMX2_WDT_WSR            0x02            /* Service Register */
  45 #define IMX2_WDT_SEQ1           0x5555          /* -> service sequence 1 */
  46 #define IMX2_WDT_SEQ2           0xAAAA          /* -> service sequence 2 */
  47
  48 #define IMX2_WDT_WRSR           0x04            /* Reset Status Register */
  49 #define IMX2_WDT_WRSR_TOUT      (1 << 1)        /* -> Reset due to Timeout */
  50
  51 #define IMX2_WDT_MAX_TIME       128
  52 #define IMX2_WDT_DEFAULT_TIME   60              /* in seconds */
  53
  54 #define WDOG_SEC_TO_COUNT(s)    ((s * 2 - 1) << 8)
  55
  56 struct imx2_wdt_device {
  57         struct clk *clk;
  58         struct regmap *regmap;
  59         struct timer_list timer;        /* Pings the watchdog when closed */
  60         struct watchdog_device wdog;
  61 };
  62
  63 static bool nowayout = WATCHDOG_NOWAYOUT;
  64 module_param(nowayout, bool, 0);
  65 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  66                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  67
  68
  69 static unsigned timeout = IMX2_WDT_DEFAULT_TIME;
  70 module_param(timeout, uint, 0);
  71 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
  72                                 __MODULE_STRING(IMX2_WDT_DEFAULT_TIME) ")");
  73
  74 static const struct watchdog_info imx2_wdt_info = {
  75         .identity = "imx2+ watchdog",
  76         .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
  77 };
  78
  79 static inline void imx2_wdt_setup(struct watchdog_device *wdog)
  80 {
  81         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
  82         u32 val;
  83
  84         regmap_read(wdev->regmap, IMX2_WDT_WCR, &val);
  85
  86         /* Suspend timer in low power mode, write once-only */
  87         val |= IMX2_WDT_WCR_WDZST;
  88         /* Strip the old watchdog Time-Out value */
  89         val &= ~IMX2_WDT_WCR_WT;
  90         /* Generate reset if WDOG times out */
  91         val &= ~IMX2_WDT_WCR_WRE;
  92         /* Keep Watchdog Disabled */
  93         val &= ~IMX2_WDT_WCR_WDE;
  94         /* Set the watchdog's Time-Out value */
  95         val |= WDOG_SEC_TO_COUNT(wdog->timeout);
  96
  97         regmap_write(wdev->regmap, IMX2_WDT_WCR, val);
  98
  99         /* enable the watchdog */
 100         val |= IMX2_WDT_WCR_WDE;
 101         regmap_write(wdev->regmap, IMX2_WDT_WCR, val);
 102 }
 103
 104 static inline bool imx2_wdt_is_running(struct imx2_wdt_device *wdev)
 105 {
 106         u32 val;
 107
 108         regmap_read(wdev->regmap, IMX2_WDT_WCR, &val);
 109
 110         return val & IMX2_WDT_WCR_WDE;
 111 }
 112
 113 static int imx2_wdt_ping(struct watchdog_device *wdog)
 114 {
 115         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 116
 117         regmap_write(wdev->regmap, IMX2_WDT_WSR, IMX2_WDT_SEQ1);
 118         regmap_write(wdev->regmap, IMX2_WDT_WSR, IMX2_WDT_SEQ2);
 119         return 0;
 120 }
 121
 122 static void imx2_wdt_timer_ping(unsigned long arg)
 123 {
 124         struct watchdog_device *wdog = (struct watchdog_device *)arg;
 125         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 126
 127         /* ping it every wdog->timeout / 2 seconds to prevent reboot */
 128         imx2_wdt_ping(wdog);
 129         mod_timer(&wdev->timer, jiffies + wdog->timeout * HZ / 2);
 130 }
 131
 132 static int imx2_wdt_set_timeout(struct watchdog_device *wdog,
 133                                 unsigned int new_timeout)
 134 {
 135         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 136
 137         regmap_update_bits(wdev->regmap, IMX2_WDT_WCR, IMX2_WDT_WCR_WT,
 138                            WDOG_SEC_TO_COUNT(new_timeout));
 139         return 0;
 140 }
 141
 142 static int imx2_wdt_start(struct watchdog_device *wdog)
 143 {
 144         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 145
 146         if (imx2_wdt_is_running(wdev)) {
 147                 /* delete the timer that pings the watchdog after close */
 148                 del_timer_sync(&wdev->timer);
 149                 imx2_wdt_set_timeout(wdog, wdog->timeout);
 150         } else
 151                 imx2_wdt_setup(wdog);
 152
 153         return imx2_wdt_ping(wdog);
 154 }
 155
 156 static int imx2_wdt_stop(struct watchdog_device *wdog)
 157 {
 158         /*
 159          * We don't need a clk_disable, it cannot be disabled once started.
 160          * We use a timer to ping the watchdog while /dev/watchdog is closed
 161          */
 162         imx2_wdt_timer_ping((unsigned long)wdog);
 163         return 0;
 164 }
 165
 166 static inline void imx2_wdt_ping_if_active(struct watchdog_device *wdog)
 167 {
 168         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 169
 170         if (imx2_wdt_is_running(wdev)) {
 171                 imx2_wdt_set_timeout(wdog, wdog->timeout);
 172                 imx2_wdt_timer_ping((unsigned long)wdog);
 173         }
 174 }
 175
 176 static struct watchdog_ops imx2_wdt_ops = {
 177         .owner = THIS_MODULE,
 178         .start = imx2_wdt_start,
 179         .stop = imx2_wdt_stop,
 180         .ping = imx2_wdt_ping,
 181         .set_timeout = imx2_wdt_set_timeout,
 182 };
 183
 184 static struct regmap_config imx2_wdt_regmap_config = {
 185         .reg_bits = 16,
 186         .reg_stride = 2,
 187         .val_bits = 16,
 188         .max_register = 0x8,
 189 };
 190
 191 static int __init imx2_wdt_probe(struct platform_device *pdev)
 192 {
 193         struct imx2_wdt_device *wdev;
 194         struct watchdog_device *wdog;
 195         struct resource *res;
 196         void __iomem *base;
 197         int ret;
 198         u32 val;
 199
 200         wdev = devm_kzalloc(&pdev->dev, sizeof(*wdev), GFP_KERNEL);
 201         if (!wdev)
 202                 return -ENOMEM;
 203
 204         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 205         base = devm_ioremap_resource(&pdev->dev, res);
 206         if (IS_ERR(base))
 207                 return PTR_ERR(base);
 208
 209         wdev->regmap = devm_regmap_init_mmio_clk(&pdev->dev, NULL, base,
 210                                                  &imx2_wdt_regmap_config);
 211         if (IS_ERR(wdev->regmap)) {
 212                 dev_err(&pdev->dev, "regmap init failed\n");
 213                 return PTR_ERR(wdev->regmap);
 214         }
 215
 216         wdev->clk = devm_clk_get(&pdev->dev, NULL);
 217         if (IS_ERR(wdev->clk)) {
 218                 dev_err(&pdev->dev, "can't get Watchdog clock\n");
 219                 return PTR_ERR(wdev->clk);
 220         }
 221
 222         wdog                    = &wdev->wdog;
 223         wdog->info              = &imx2_wdt_info;
 224         wdog->ops               = &imx2_wdt_ops;
 225         wdog->min_timeout       = 1;
 226         wdog->max_timeout       = IMX2_WDT_MAX_TIME;
 227
 228         clk_prepare_enable(wdev->clk);
 229
 230         regmap_read(wdev->regmap, IMX2_WDT_WRSR, &val);
 231         wdog->bootstatus = val & IMX2_WDT_WRSR_TOUT ? WDIOF_CARDRESET : 0;
 232
 233         wdog->timeout = clamp_t(unsigned, timeout, 1, IMX2_WDT_MAX_TIME);
 234         if (wdog->timeout != timeout)
 235                 dev_warn(&pdev->dev, "Initial timeout out of range! Clamped from %u to %u\n",
 236                          timeout, wdog->timeout);
 237
 238         platform_set_drvdata(pdev, wdog);
 239         watchdog_set_drvdata(wdog, wdev);
 240         watchdog_set_nowayout(wdog, nowayout);
 241         watchdog_init_timeout(wdog, timeout, &pdev->dev);
 242
 243         setup_timer(&wdev->timer, imx2_wdt_timer_ping, (unsigned long)wdog);
 244
 245         imx2_wdt_ping_if_active(wdog);
 246
 247         ret = watchdog_register_device(wdog);
 248         if (ret) {
 249                 dev_err(&pdev->dev, "cannot register watchdog device\n");
 250                 return ret;
 251         }
 252
 253         dev_info(&pdev->dev, "timeout %d sec (nowayout=%d)\n",
 254                  wdog->timeout, nowayout);
 255
 256         return 0;
 257 }
 258
 259 static int __exit imx2_wdt_remove(struct platform_device *pdev)
 260 {
 261         struct watchdog_device *wdog = platform_get_drvdata(pdev);
 262         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 263
 264         watchdog_unregister_device(wdog);
 265
 266         if (imx2_wdt_is_running(wdev)) {
 267                 del_timer_sync(&wdev->timer);
 268                 imx2_wdt_ping(wdog);
 269                 dev_crit(&pdev->dev, "Device removed: Expect reboot!\n");
 270         }
 271         return 0;
 272 }
 273
 274 static void imx2_wdt_shutdown(struct platform_device *pdev)
 275 {
 276         struct watchdog_device *wdog = platform_get_drvdata(pdev);
 277         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 278
 279         if (imx2_wdt_is_running(wdev)) {
 280                 /*
 281                  * We are running, we need to delete the timer but will
 282                  * give max timeout before reboot will take place
 283                  */
 284                 del_timer_sync(&wdev->timer);
 285                 imx2_wdt_set_timeout(wdog, IMX2_WDT_MAX_TIME);
 286                 imx2_wdt_ping(wdog);
 287                 dev_crit(&pdev->dev, "Device shutdown: Expect reboot!\n");
 288         }
 289 }
 290
 291 static const struct of_device_id imx2_wdt_dt_ids[] = {
 292         { .compatible = "fsl,imx21-wdt", },
 293         { /* sentinel */ }
 294 };
 295 MODULE_DEVICE_TABLE(of, imx2_wdt_dt_ids);
 296
 297 static struct platform_driver imx2_wdt_driver = {
 298         .remove         = __exit_p(imx2_wdt_remove),
 299         .shutdown       = imx2_wdt_shutdown,
 300         .driver         = {
 301                 .name   = DRIVER_NAME,
 302                 .owner  = THIS_MODULE,
 303                 .of_match_table = imx2_wdt_dt_ids,
 304         },
 305 };
 306
 307 module_platform_driver_probe(imx2_wdt_driver, imx2_wdt_probe);
 308
 309 MODULE_AUTHOR("Wolfram Sang");
 310 MODULE_DESCRIPTION("Watchdog driver for IMX2 and later");
 311 MODULE_LICENSE("GPL v2");
 312 MODULE_ALIAS("platform:" DRIVER_NAME);