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         bool clk_is_on;
  69 };
  70
  71 static bool nowayout = WATCHDOG_NOWAYOUT;
  72 module_param(nowayout, bool, 0);
  73 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  74                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  75
  76 static unsigned timeout;
  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 const struct watchdog_info imx2_wdt_pretimeout_info = {
  87         .identity = "imx2+ watchdog",
  88         .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
  89                    WDIOF_PRETIMEOUT,
  90 };
  91
  92 static int imx2_wdt_restart(struct watchdog_device *wdog, unsigned long action,
  93                             void *data)
  94 {
  95         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
  96         unsigned int wcr_enable = IMX2_WDT_WCR_WDE;
  97
  98         /* Use internal reset or external - not both */
  99         if (wdev->ext_reset)
 100                 wcr_enable |= IMX2_WDT_WCR_SRS; /* do not assert int reset */
 101         else
 102                 wcr_enable |= IMX2_WDT_WCR_WDA; /* do not assert ext-reset */
 103
 104         /* Assert SRS signal */
 105         regmap_write(wdev->regmap, IMX2_WDT_WCR, wcr_enable);
 106         /*
 107          * Due to imx6q errata ERR004346 (WDOG: WDOG SRS bit requires to be
 108          * written twice), we add another two writes to ensure there must be at
 109          * least two writes happen in the same one 32kHz clock period.  We save
 110          * the target check here, since the writes shouldn't be a huge burden
 111          * for other platforms.
 112          */
 113         regmap_write(wdev->regmap, IMX2_WDT_WCR, wcr_enable);
 114         regmap_write(wdev->regmap, IMX2_WDT_WCR, wcr_enable);
 115
 116         /* wait for reset to assert... */
 117         mdelay(500);
 118
 119         return 0;
 120 }
 121
 122 static inline void imx2_wdt_setup(struct watchdog_device *wdog)
 123 {
 124         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 125         u32 val;
 126
 127         regmap_read(wdev->regmap, IMX2_WDT_WCR, &val);
 128
 129         /* Suspend timer in low power mode, write once-only */
 130         val |= IMX2_WDT_WCR_WDZST;
 131         /* Strip the old watchdog Time-Out value */
 132         val &= ~IMX2_WDT_WCR_WT;
 133         /* Generate internal chip-level reset if WDOG times out */
 134         if (!wdev->ext_reset)
 135                 val &= ~IMX2_WDT_WCR_WRE;
 136         /* Or if external-reset assert WDOG_B reset only on time-out */
 137         else
 138                 val |= IMX2_WDT_WCR_WRE;
 139         /* Keep Watchdog Disabled */
 140         val &= ~IMX2_WDT_WCR_WDE;
 141         /* Set the watchdog's Time-Out value */
 142         val |= WDOG_SEC_TO_COUNT(wdog->timeout);
 143
 144         regmap_write(wdev->regmap, IMX2_WDT_WCR, val);
 145
 146         /* enable the watchdog */
 147         val |= IMX2_WDT_WCR_WDE;
 148         regmap_write(wdev->regmap, IMX2_WDT_WCR, val);
 149 }
 150
 151 static inline bool imx2_wdt_is_running(struct imx2_wdt_device *wdev)
 152 {
 153         u32 val;
 154
 155         regmap_read(wdev->regmap, IMX2_WDT_WCR, &val);
 156
 157         return val & IMX2_WDT_WCR_WDE;
 158 }
 159
 160 static int imx2_wdt_ping(struct watchdog_device *wdog)
 161 {
 162         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 163
 164         if (!wdev->clk_is_on)
 165                 return 0;
 166
 167         regmap_write(wdev->regmap, IMX2_WDT_WSR, IMX2_WDT_SEQ1);
 168         regmap_write(wdev->regmap, IMX2_WDT_WSR, IMX2_WDT_SEQ2);
 169         return 0;
 170 }
 171
 172 static void __imx2_wdt_set_timeout(struct watchdog_device *wdog,
 173                                    unsigned int new_timeout)
 174 {
 175         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 176
 177         regmap_update_bits(wdev->regmap, IMX2_WDT_WCR, IMX2_WDT_WCR_WT,
 178                            WDOG_SEC_TO_COUNT(new_timeout));
 179 }
 180
 181 static int imx2_wdt_set_timeout(struct watchdog_device *wdog,
 182                                 unsigned int new_timeout)
 183 {
 184         unsigned int actual;
 185
 186         actual = min(new_timeout, IMX2_WDT_MAX_TIME);
 187         __imx2_wdt_set_timeout(wdog, actual);
 188         wdog->timeout = new_timeout;
 189         return 0;
 190 }
 191
 192 static int imx2_wdt_set_pretimeout(struct watchdog_device *wdog,
 193                                    unsigned int new_pretimeout)
 194 {
 195         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 196
 197         if (new_pretimeout >= IMX2_WDT_MAX_TIME)
 198                 return -EINVAL;
 199
 200         wdog->pretimeout = new_pretimeout;
 201
 202         regmap_update_bits(wdev->regmap, IMX2_WDT_WICR,
 203                            IMX2_WDT_WICR_WIE | IMX2_WDT_WICR_WICT,
 204                            IMX2_WDT_WICR_WIE | (new_pretimeout << 1));
 205         return 0;
 206 }
 207
 208 static irqreturn_t imx2_wdt_isr(int irq, void *wdog_arg)
 209 {
 210         struct watchdog_device *wdog = wdog_arg;
 211         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 212
 213         regmap_write_bits(wdev->regmap, IMX2_WDT_WICR,
 214                           IMX2_WDT_WICR_WTIS, IMX2_WDT_WICR_WTIS);
 215
 216         watchdog_notify_pretimeout(wdog);
 217
 218         return IRQ_HANDLED;
 219 }
 220
 221 static int imx2_wdt_start(struct watchdog_device *wdog)
 222 {
 223         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 224
 225         if (imx2_wdt_is_running(wdev))
 226                 imx2_wdt_set_timeout(wdog, wdog->timeout);
 227         else
 228                 imx2_wdt_setup(wdog);
 229
 230         set_bit(WDOG_HW_RUNNING, &wdog->status);
 231
 232         return imx2_wdt_ping(wdog);
 233 }
 234
 235 static const struct watchdog_ops imx2_wdt_ops = {
 236         .owner = THIS_MODULE,
 237         .start = imx2_wdt_start,
 238         .ping = imx2_wdt_ping,
 239         .set_timeout = imx2_wdt_set_timeout,
 240         .set_pretimeout = imx2_wdt_set_pretimeout,
 241         .restart = imx2_wdt_restart,
 242 };
 243
 244 static const struct regmap_config imx2_wdt_regmap_config = {
 245         .reg_bits = 16,
 246         .reg_stride = 2,
 247         .val_bits = 16,
 248         .max_register = 0x8,
 249 };
 250
 251 static void imx2_wdt_action(void *data)
 252 {
 253         clk_disable_unprepare(data);
 254 }
 255
 256 static int __init imx2_wdt_probe(struct platform_device *pdev)
 257 {
 258         struct device *dev = &pdev->dev;
 259         struct imx2_wdt_device *wdev;
 260         struct watchdog_device *wdog;
 261         void __iomem *base;
 262         int ret;
 263         u32 val;
 264
 265         wdev = devm_kzalloc(dev, sizeof(*wdev), GFP_KERNEL);
 266         if (!wdev)
 267                 return -ENOMEM;
 268
 269         base = devm_platform_ioremap_resource(pdev, 0);
 270         if (IS_ERR(base))
 271                 return PTR_ERR(base);
 272
 273         wdev->regmap = devm_regmap_init_mmio_clk(dev, NULL, base,
 274                                                  &imx2_wdt_regmap_config);
 275         if (IS_ERR(wdev->regmap)) {
 276                 dev_err(dev, "regmap init failed\n");
 277                 return PTR_ERR(wdev->regmap);
 278         }
 279
 280         wdev->clk = devm_clk_get(dev, NULL);
 281         if (IS_ERR(wdev->clk)) {
 282                 dev_err(dev, "can't get Watchdog clock\n");
 283                 return PTR_ERR(wdev->clk);
 284         }
 285
 286         wdog                    = &wdev->wdog;
 287         wdog->info              = &imx2_wdt_info;
 288         wdog->ops               = &imx2_wdt_ops;
 289         wdog->min_timeout       = 1;
 290         wdog->timeout           = IMX2_WDT_DEFAULT_TIME;
 291         wdog->max_hw_heartbeat_ms = IMX2_WDT_MAX_TIME * 1000;
 292         wdog->parent            = dev;
 293
 294         ret = platform_get_irq(pdev, 0);
 295         if (ret > 0)
 296                 if (!devm_request_irq(dev, ret, imx2_wdt_isr, 0,
 297                                       dev_name(dev), wdog))
 298                         wdog->info = &imx2_wdt_pretimeout_info;
 299
 300         ret = clk_prepare_enable(wdev->clk);
 301         if (ret)
 302                 return ret;
 303
 304         ret = devm_add_action_or_reset(dev, imx2_wdt_action, wdev->clk);
 305         if (ret)
 306                 return ret;
 307
 308         wdev->clk_is_on = true;
 309
 310         regmap_read(wdev->regmap, IMX2_WDT_WRSR, &val);
 311         wdog->bootstatus = val & IMX2_WDT_WRSR_TOUT ? WDIOF_CARDRESET : 0;
 312
 313         wdev->ext_reset = of_property_read_bool(dev->of_node,
 314                                                 "fsl,ext-reset-output");
 315         platform_set_drvdata(pdev, wdog);
 316         watchdog_set_drvdata(wdog, wdev);
 317         watchdog_set_nowayout(wdog, nowayout);
 318         watchdog_set_restart_priority(wdog, 128);
 319         watchdog_init_timeout(wdog, timeout, dev);
 320         watchdog_stop_ping_on_suspend(wdog);
 321
 322         if (imx2_wdt_is_running(wdev)) {
 323                 imx2_wdt_set_timeout(wdog, wdog->timeout);
 324                 set_bit(WDOG_HW_RUNNING, &wdog->status);
 325         }
 326
 327         /*
 328          * Disable the watchdog power down counter at boot. Otherwise the power
 329          * down counter will pull down the #WDOG interrupt line for one clock
 330          * cycle.
 331          */
 332         regmap_write(wdev->regmap, IMX2_WDT_WMCR, 0);
 333
 334         return devm_watchdog_register_device(dev, wdog);
 335 }
 336
 337 static void imx2_wdt_shutdown(struct platform_device *pdev)
 338 {
 339         struct watchdog_device *wdog = platform_get_drvdata(pdev);
 340         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 341
 342         if (imx2_wdt_is_running(wdev)) {
 343                 /*
 344                  * We are running, configure max timeout before reboot
 345                  * will take place.
 346                  */
 347                 imx2_wdt_set_timeout(wdog, IMX2_WDT_MAX_TIME);
 348                 imx2_wdt_ping(wdog);
 349                 dev_crit(&pdev->dev, "Device shutdown: Expect reboot!\n");
 350         }
 351 }
 352
 353 /* Disable watchdog if it is active or non-active but still running */
 354 static int __maybe_unused imx2_wdt_suspend(struct device *dev)
 355 {
 356         struct watchdog_device *wdog = dev_get_drvdata(dev);
 357         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 358
 359         /* The watchdog IP block is running */
 360         if (imx2_wdt_is_running(wdev)) {
 361                 /*
 362                  * Don't update wdog->timeout, we'll restore the current value
 363                  * during resume.
 364                  */
 365                 __imx2_wdt_set_timeout(wdog, IMX2_WDT_MAX_TIME);
 366                 imx2_wdt_ping(wdog);
 367         }
 368
 369         clk_disable_unprepare(wdev->clk);
 370
 371         wdev->clk_is_on = false;
 372
 373         return 0;
 374 }
 375
 376 /* Enable watchdog and configure it if necessary */
 377 static int __maybe_unused imx2_wdt_resume(struct device *dev)
 378 {
 379         struct watchdog_device *wdog = dev_get_drvdata(dev);
 380         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 381         int ret;
 382
 383         ret = clk_prepare_enable(wdev->clk);
 384         if (ret)
 385                 return ret;
 386
 387         wdev->clk_is_on = true;
 388
 389         if (watchdog_active(wdog) && !imx2_wdt_is_running(wdev)) {
 390                 /*
 391                  * If the watchdog is still active and resumes
 392                  * from deep sleep state, need to restart the
 393                  * watchdog again.
 394                  */
 395                 imx2_wdt_setup(wdog);
 396         }
 397         if (imx2_wdt_is_running(wdev)) {
 398                 imx2_wdt_set_timeout(wdog, wdog->timeout);
 399                 imx2_wdt_ping(wdog);
 400         }
 401
 402         return 0;
 403 }
 404
 405 static SIMPLE_DEV_PM_OPS(imx2_wdt_pm_ops, imx2_wdt_suspend,
 406                          imx2_wdt_resume);
 407
 408 static const struct of_device_id imx2_wdt_dt_ids[] = {
 409         { .compatible = "fsl,imx21-wdt", },
 410         { /* sentinel */ }
 411 };
 412 MODULE_DEVICE_TABLE(of, imx2_wdt_dt_ids);
 413
 414 static struct platform_driver imx2_wdt_driver = {
 415         .shutdown       = imx2_wdt_shutdown,
 416         .driver         = {
 417                 .name   = DRIVER_NAME,
 418                 .pm     = &imx2_wdt_pm_ops,
 419                 .of_match_table = imx2_wdt_dt_ids,
 420         },
 421 };
 422
 423 module_platform_driver_probe(imx2_wdt_driver, imx2_wdt_probe);
 424
 425 MODULE_AUTHOR("Wolfram Sang");
 426 MODULE_DESCRIPTION("Watchdog driver for IMX2 and later");
 427 MODULE_LICENSE("GPL v2");
 428 MODULE_ALIAS("platform:" DRIVER_NAME);