drivers/watchdog/imx2_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Watchdog driver for IMX2 and later processors
   4  *
   5  *  Copyright (C) 2010 Wolfram Sang, Pengutronix e.K. <kernel@pengutronix.de>
   6  *  Copyright (C) 2014 Freescale Semiconductor, Inc.
   7  *
   8  * some parts adapted by similar drivers from Darius Augulis and Vladimir
   9  * Zapolskiy, additional improvements by Wim Van Sebroeck.
  10  *
  11  * NOTE: MX1 has a slightly different Watchdog than MX2 and later:
  12  *
  13  *                      MX1:            MX2+:
  14  *                      ----            -----
  15  * Registers:           32-bit          16-bit
  16  * Stopable timer:      Yes             No
  17  * Need to enable clk:  No              Yes
  18  * Halt on suspend:     Manual          Can be automatic
  19  */
  20
  21 #include <linux/clk.h>
  22 #include <linux/delay.h>
  23 #include <linux/init.h>
  24 #include <linux/interrupt.h>
  25 #include <linux/io.h>
  26 #include <linux/kernel.h>
  27 #include <linux/module.h>
  28 #include <linux/moduleparam.h>
  29 #include <linux/of_address.h>
  30 #include <linux/platform_device.h>
  31 #include <linux/regmap.h>
  32 #include <linux/watchdog.h>
  33
  34 #define DRIVER_NAME "imx2-wdt"
  35
  36 #define IMX2_WDT_WCR            0x00            /* Control Register */
  37 #define IMX2_WDT_WCR_WT         (0xFF << 8)     /* -> Watchdog Timeout Field */
  38 #define IMX2_WDT_WCR_WDA        BIT(5)          /* -> External Reset WDOG_B */
  39 #define IMX2_WDT_WCR_SRS        BIT(4)          /* -> Software Reset Signal */
  40 #define IMX2_WDT_WCR_WRE        BIT(3)          /* -> WDOG Reset Enable */
  41 #define IMX2_WDT_WCR_WDE        BIT(2)          /* -> Watchdog Enable */
  42 #define IMX2_WDT_WCR_WDZST      BIT(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      BIT(1)          /* -> Reset due to Timeout */
  50
  51 #define IMX2_WDT_WICR           0x06            /* Interrupt Control Register */
  52 #define IMX2_WDT_WICR_WIE       BIT(15)         /* -> Interrupt Enable */
  53 #define IMX2_WDT_WICR_WTIS      BIT(14)         /* -> Interrupt Status */
  54 #define IMX2_WDT_WICR_WICT      0xFF            /* -> Interrupt Count Timeout */
  55
  56 #define IMX2_WDT_WMCR           0x08            /* Misc Register */
  57
  58 #define IMX2_WDT_MAX_TIME       128U
  59 #define IMX2_WDT_DEFAULT_TIME   60              /* in seconds */
  60
  61 #define WDOG_SEC_TO_COUNT(s)    ((s * 2 - 1) << 8)
  62
  63 struct imx2_wdt_device {
  64         struct clk *clk;
  65         struct regmap *regmap;
  66         struct watchdog_device wdog;
  67         bool ext_reset;
  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 static unsigned timeout;
  76 module_param(timeout, uint, 0);
  77 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
  78                                 __MODULE_STRING(IMX2_WDT_DEFAULT_TIME) ")");
  79
  80 static const struct watchdog_info imx2_wdt_info = {
  81         .identity = "imx2+ watchdog",
  82         .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
  83 };
  84
  85 static const struct watchdog_info imx2_wdt_pretimeout_info = {
  86         .identity = "imx2+ watchdog",
  87         .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
  88                    WDIOF_PRETIMEOUT,
  89 };
  90
  91 static int imx2_wdt_restart(struct watchdog_device *wdog, unsigned long action,
  92                             void *data)
  93 {
  94         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
  95         unsigned int wcr_enable = IMX2_WDT_WCR_WDE;
  96
  97         /* Use internal reset or external - not both */
  98         if (wdev->ext_reset)
  99                 wcr_enable |= IMX2_WDT_WCR_SRS; /* do not assert int reset */
 100         else
 101                 wcr_enable |= IMX2_WDT_WCR_WDA; /* do not assert ext-reset */
 102
 103         /* Assert SRS signal */
 104         regmap_write(wdev->regmap, IMX2_WDT_WCR, wcr_enable);
 105         /*
 106          * Due to imx6q errata ERR004346 (WDOG: WDOG SRS bit requires to be
 107          * written twice), we add another two writes to ensure there must be at
 108          * least two writes happen in the same one 32kHz clock period.  We save
 109          * the target check here, since the writes shouldn't be a huge burden
 110          * for other platforms.
 111          */
 112         regmap_write(wdev->regmap, IMX2_WDT_WCR, wcr_enable);
 113         regmap_write(wdev->regmap, IMX2_WDT_WCR, wcr_enable);
 114
 115         /* wait for reset to assert... */
 116         mdelay(500);
 117
 118         return 0;
 119 }
 120
 121 static inline void imx2_wdt_setup(struct watchdog_device *wdog)
 122 {
 123         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 124         u32 val;
 125
 126         regmap_read(wdev->regmap, IMX2_WDT_WCR, &val);
 127
 128         /* Suspend timer in low power mode, write once-only */
 129         val |= IMX2_WDT_WCR_WDZST;
 130         /* Strip the old watchdog Time-Out value */
 131         val &= ~IMX2_WDT_WCR_WT;
 132         /* Generate internal chip-level reset if WDOG times out */
 133         if (!wdev->ext_reset)
 134                 val &= ~IMX2_WDT_WCR_WRE;
 135         /* Or if external-reset assert WDOG_B reset only on time-out */
 136         else
 137                 val |= IMX2_WDT_WCR_WRE;
 138         /* Keep Watchdog Disabled */
 139         val &= ~IMX2_WDT_WCR_WDE;
 140         /* Set the watchdog's Time-Out value */
 141         val |= WDOG_SEC_TO_COUNT(wdog->timeout);
 142
 143         regmap_write(wdev->regmap, IMX2_WDT_WCR, val);
 144
 145         /* enable the watchdog */
 146         val |= IMX2_WDT_WCR_WDE;
 147         regmap_write(wdev->regmap, IMX2_WDT_WCR, val);
 148 }
 149
 150 static inline bool imx2_wdt_is_running(struct imx2_wdt_device *wdev)
 151 {
 152         u32 val;
 153
 154         regmap_read(wdev->regmap, IMX2_WDT_WCR, &val);
 155
 156         return val & IMX2_WDT_WCR_WDE;
 157 }
 158
 159 static int imx2_wdt_ping(struct watchdog_device *wdog)
 160 {
 161         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 162
 163         regmap_write(wdev->regmap, IMX2_WDT_WSR, IMX2_WDT_SEQ1);
 164         regmap_write(wdev->regmap, IMX2_WDT_WSR, IMX2_WDT_SEQ2);
 165         return 0;
 166 }
 167
 168 static void __imx2_wdt_set_timeout(struct watchdog_device *wdog,
 169                                    unsigned int new_timeout)
 170 {
 171         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 172
 173         regmap_update_bits(wdev->regmap, IMX2_WDT_WCR, IMX2_WDT_WCR_WT,
 174                            WDOG_SEC_TO_COUNT(new_timeout));
 175 }
 176
 177 static int imx2_wdt_set_timeout(struct watchdog_device *wdog,
 178                                 unsigned int new_timeout)
 179 {
 180         unsigned int actual;
 181
 182         actual = min(new_timeout, IMX2_WDT_MAX_TIME);
 183         __imx2_wdt_set_timeout(wdog, actual);
 184         wdog->timeout = new_timeout;
 185         return 0;
 186 }
 187
 188 static int imx2_wdt_set_pretimeout(struct watchdog_device *wdog,
 189                                    unsigned int new_pretimeout)
 190 {
 191         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 192
 193         if (new_pretimeout >= IMX2_WDT_MAX_TIME)
 194                 return -EINVAL;
 195
 196         wdog->pretimeout = new_pretimeout;
 197
 198         regmap_update_bits(wdev->regmap, IMX2_WDT_WICR,
 199                            IMX2_WDT_WICR_WIE | IMX2_WDT_WICR_WICT,
 200                            IMX2_WDT_WICR_WIE | (new_pretimeout << 1));
 201         return 0;
 202 }
 203
 204 static irqreturn_t imx2_wdt_isr(int irq, void *wdog_arg)
 205 {
 206         struct watchdog_device *wdog = wdog_arg;
 207         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 208
 209         regmap_write_bits(wdev->regmap, IMX2_WDT_WICR,
 210                           IMX2_WDT_WICR_WTIS, IMX2_WDT_WICR_WTIS);
 211
 212         watchdog_notify_pretimeout(wdog);
 213
 214         return IRQ_HANDLED;
 215 }
 216
 217 static int imx2_wdt_start(struct watchdog_device *wdog)
 218 {
 219         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 220
 221         if (imx2_wdt_is_running(wdev))
 222                 imx2_wdt_set_timeout(wdog, wdog->timeout);
 223         else
 224                 imx2_wdt_setup(wdog);
 225
 226         set_bit(WDOG_HW_RUNNING, &wdog->status);
 227
 228         return imx2_wdt_ping(wdog);
 229 }
 230
 231 static const struct watchdog_ops imx2_wdt_ops = {
 232         .owner = THIS_MODULE,
 233         .start = imx2_wdt_start,
 234         .ping = imx2_wdt_ping,
 235         .set_timeout = imx2_wdt_set_timeout,
 236         .set_pretimeout = imx2_wdt_set_pretimeout,
 237         .restart = imx2_wdt_restart,
 238 };
 239
 240 static const struct regmap_config imx2_wdt_regmap_config = {
 241         .reg_bits = 16,
 242         .reg_stride = 2,
 243         .val_bits = 16,
 244         .max_register = 0x8,
 245 };
 246
 247 static void imx2_wdt_action(void *data)
 248 {
 249         clk_disable_unprepare(data);
 250 }
 251
 252 static int __init imx2_wdt_probe(struct platform_device *pdev)
 253 {
 254         struct device *dev = &pdev->dev;
 255         struct imx2_wdt_device *wdev;
 256         struct watchdog_device *wdog;
 257         void __iomem *base;
 258         int ret;
 259         u32 val;
 260
 261         wdev = devm_kzalloc(dev, sizeof(*wdev), GFP_KERNEL);
 262         if (!wdev)
 263                 return -ENOMEM;
 264
 265         base = devm_platform_ioremap_resource(pdev, 0);
 266         if (IS_ERR(base))
 267                 return PTR_ERR(base);
 268
 269         wdev->regmap = devm_regmap_init_mmio_clk(dev, NULL, base,
 270                                                  &imx2_wdt_regmap_config);
 271         if (IS_ERR(wdev->regmap)) {
 272                 dev_err(dev, "regmap init failed\n");
 273                 return PTR_ERR(wdev->regmap);
 274         }
 275
 276         wdev->clk = devm_clk_get(dev, NULL);
 277         if (IS_ERR(wdev->clk)) {
 278                 dev_err(dev, "can't get Watchdog clock\n");
 279                 return PTR_ERR(wdev->clk);
 280         }
 281
 282         wdog                    = &wdev->wdog;
 283         wdog->info              = &imx2_wdt_info;
 284         wdog->ops               = &imx2_wdt_ops;
 285         wdog->min_timeout       = 1;
 286         wdog->timeout           = IMX2_WDT_DEFAULT_TIME;
 287         wdog->max_hw_heartbeat_ms = IMX2_WDT_MAX_TIME * 1000;
 288         wdog->parent            = dev;
 289
 290         ret = platform_get_irq(pdev, 0);
 291         if (ret > 0)
 292                 if (!devm_request_irq(dev, ret, imx2_wdt_isr, 0,
 293                                       dev_name(dev), wdog))
 294                         wdog->info = &imx2_wdt_pretimeout_info;
 295
 296         ret = clk_prepare_enable(wdev->clk);
 297         if (ret)
 298                 return ret;
 299
 300         ret = devm_add_action_or_reset(dev, imx2_wdt_action, wdev->clk);
 301         if (ret)
 302                 return ret;
 303
 304         regmap_read(wdev->regmap, IMX2_WDT_WRSR, &val);
 305         wdog->bootstatus = val & IMX2_WDT_WRSR_TOUT ? WDIOF_CARDRESET : 0;
 306
 307         wdev->ext_reset = of_property_read_bool(dev->of_node,
 308                                                 "fsl,ext-reset-output");
 309         platform_set_drvdata(pdev, wdog);
 310         watchdog_set_drvdata(wdog, wdev);
 311         watchdog_set_nowayout(wdog, nowayout);
 312         watchdog_set_restart_priority(wdog, 128);
 313         watchdog_init_timeout(wdog, timeout, dev);
 314
 315         if (imx2_wdt_is_running(wdev)) {
 316                 imx2_wdt_set_timeout(wdog, wdog->timeout);
 317                 set_bit(WDOG_HW_RUNNING, &wdog->status);
 318         }
 319
 320         /*
 321          * Disable the watchdog power down counter at boot. Otherwise the power
 322          * down counter will pull down the #WDOG interrupt line for one clock
 323          * cycle.
 324          */
 325         regmap_write(wdev->regmap, IMX2_WDT_WMCR, 0);
 326
 327         return devm_watchdog_register_device(dev, wdog);
 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, configure max timeout before reboot
 338                  * will take place.
 339                  */
 340                 imx2_wdt_set_timeout(wdog, IMX2_WDT_MAX_TIME);
 341                 imx2_wdt_ping(wdog);
 342                 dev_crit(&pdev->dev, "Device shutdown: Expect reboot!\n");
 343         }
 344 }
 345
 346 /* Disable watchdog if it is active or non-active but still running */
 347 static int __maybe_unused imx2_wdt_suspend(struct device *dev)
 348 {
 349         struct watchdog_device *wdog = dev_get_drvdata(dev);
 350         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 351
 352         /* The watchdog IP block is running */
 353         if (imx2_wdt_is_running(wdev)) {
 354                 /*
 355                  * Don't update wdog->timeout, we'll restore the current value
 356                  * during resume.
 357                  */
 358                 __imx2_wdt_set_timeout(wdog, IMX2_WDT_MAX_TIME);
 359                 imx2_wdt_ping(wdog);
 360         }
 361
 362         clk_disable_unprepare(wdev->clk);
 363
 364         return 0;
 365 }
 366
 367 /* Enable watchdog and configure it if necessary */
 368 static int __maybe_unused imx2_wdt_resume(struct device *dev)
 369 {
 370         struct watchdog_device *wdog = dev_get_drvdata(dev);
 371         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 372         int ret;
 373
 374         ret = clk_prepare_enable(wdev->clk);
 375         if (ret)
 376                 return ret;
 377
 378         if (watchdog_active(wdog) && !imx2_wdt_is_running(wdev)) {
 379                 /*
 380                  * If the watchdog is still active and resumes
 381                  * from deep sleep state, need to restart the
 382                  * watchdog again.
 383                  */
 384                 imx2_wdt_setup(wdog);
 385         }
 386         if (imx2_wdt_is_running(wdev)) {
 387                 imx2_wdt_set_timeout(wdog, wdog->timeout);
 388                 imx2_wdt_ping(wdog);
 389         }
 390
 391         return 0;
 392 }
 393
 394 static SIMPLE_DEV_PM_OPS(imx2_wdt_pm_ops, imx2_wdt_suspend,
 395                          imx2_wdt_resume);
 396
 397 static const struct of_device_id imx2_wdt_dt_ids[] = {
 398         { .compatible = "fsl,imx21-wdt", },
 399         { /* sentinel */ }
 400 };
 401 MODULE_DEVICE_TABLE(of, imx2_wdt_dt_ids);
 402
 403 static struct platform_driver imx2_wdt_driver = {
 404         .shutdown       = imx2_wdt_shutdown,
 405         .driver         = {
 406                 .name   = DRIVER_NAME,
 407                 .pm     = &imx2_wdt_pm_ops,
 408                 .of_match_table = imx2_wdt_dt_ids,
 409         },
 410 };
 411
 412 module_platform_driver_probe(imx2_wdt_driver, imx2_wdt_probe);
 413
 414 MODULE_AUTHOR("Wolfram Sang");
 415 MODULE_DESCRIPTION("Watchdog driver for IMX2 and later");
 416 MODULE_LICENSE("GPL v2");
 417 MODULE_ALIAS("platform:" DRIVER_NAME);