drivers/watchdog/sama5d4_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Driver for Atmel SAMA5D4 Watchdog Timer
   4  *
   5  * Copyright (C) 2015-2019 Microchip Technology Inc. and its subsidiaries
   6  */
   7
   8 #include <linux/delay.h>
   9 #include <linux/interrupt.h>
  10 #include <linux/io.h>
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <linux/of.h>
  14 #include <linux/of_device.h>
  15 #include <linux/of_irq.h>
  16 #include <linux/platform_device.h>
  17 #include <linux/reboot.h>
  18 #include <linux/watchdog.h>
  19
  20 #include "at91sam9_wdt.h"
  21
  22 /* minimum and maximum watchdog timeout, in seconds */
  23 #define MIN_WDT_TIMEOUT         1
  24 #define MAX_WDT_TIMEOUT         16
  25 #define WDT_DEFAULT_TIMEOUT     MAX_WDT_TIMEOUT
  26
  27 #define WDT_SEC2TICKS(s)        ((s) ? (((s) << 8) - 1) : 0)
  28
  29 struct sama5d4_wdt {
  30         struct watchdog_device  wdd;
  31         void __iomem            *reg_base;
  32         u32                     mr;
  33         u32                     ir;
  34         unsigned long           last_ping;
  35         bool                    need_irq;
  36         bool                    sam9x60_support;
  37 };
  38
  39 static int wdt_timeout;
  40 static bool nowayout = WATCHDOG_NOWAYOUT;
  41
  42 module_param(wdt_timeout, int, 0);
  43 MODULE_PARM_DESC(wdt_timeout,
  44         "Watchdog timeout in seconds. (default = "
  45         __MODULE_STRING(WDT_DEFAULT_TIMEOUT) ")");
  46
  47 module_param(nowayout, bool, 0);
  48 MODULE_PARM_DESC(nowayout,
  49         "Watchdog cannot be stopped once started (default="
  50         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  51
  52 #define wdt_enabled (!(wdt->mr & AT91_WDT_WDDIS))
  53
  54 #define wdt_read(wdt, field) \
  55         readl_relaxed((wdt)->reg_base + (field))
  56
  57 /* 4 slow clock periods is 4/32768 = 122.07µs*/
  58 #define WDT_DELAY       usecs_to_jiffies(123)
  59
  60 static void wdt_write(struct sama5d4_wdt *wdt, u32 field, u32 val)
  61 {
  62         /*
  63          * WDT_CR and WDT_MR must not be modified within three slow clock
  64          * periods following a restart of the watchdog performed by a write
  65          * access in WDT_CR.
  66          */
  67         while (time_before(jiffies, wdt->last_ping + WDT_DELAY))
  68                 usleep_range(30, 125);
  69         writel_relaxed(val, wdt->reg_base + field);
  70         wdt->last_ping = jiffies;
  71 }
  72
  73 static void wdt_write_nosleep(struct sama5d4_wdt *wdt, u32 field, u32 val)
  74 {
  75         if (time_before(jiffies, wdt->last_ping + WDT_DELAY))
  76                 udelay(123);
  77         writel_relaxed(val, wdt->reg_base + field);
  78         wdt->last_ping = jiffies;
  79 }
  80
  81 static int sama5d4_wdt_start(struct watchdog_device *wdd)
  82 {
  83         struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
  84
  85         if (wdt->sam9x60_support) {
  86                 writel_relaxed(wdt->ir, wdt->reg_base + AT91_SAM9X60_IER);
  87                 wdt->mr &= ~AT91_SAM9X60_WDDIS;
  88         } else {
  89                 wdt->mr &= ~AT91_WDT_WDDIS;
  90         }
  91         wdt_write(wdt, AT91_WDT_MR, wdt->mr);
  92
  93         return 0;
  94 }
  95
  96 static int sama5d4_wdt_stop(struct watchdog_device *wdd)
  97 {
  98         struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
  99
 100         if (wdt->sam9x60_support) {
 101                 writel_relaxed(wdt->ir, wdt->reg_base + AT91_SAM9X60_IDR);
 102                 wdt->mr |= AT91_SAM9X60_WDDIS;
 103         } else {
 104                 wdt->mr |= AT91_WDT_WDDIS;
 105         }
 106         wdt_write(wdt, AT91_WDT_MR, wdt->mr);
 107
 108         return 0;
 109 }
 110
 111 static int sama5d4_wdt_ping(struct watchdog_device *wdd)
 112 {
 113         struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
 114
 115         wdt_write(wdt, AT91_WDT_CR, AT91_WDT_KEY | AT91_WDT_WDRSTT);
 116
 117         return 0;
 118 }
 119
 120 static int sama5d4_wdt_set_timeout(struct watchdog_device *wdd,
 121                                  unsigned int timeout)
 122 {
 123         struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
 124         u32 value = WDT_SEC2TICKS(timeout);
 125
 126         if (wdt->sam9x60_support) {
 127                 wdt_write(wdt, AT91_SAM9X60_WLR,
 128                           AT91_SAM9X60_SET_COUNTER(value));
 129
 130                 wdd->timeout = timeout;
 131                 return 0;
 132         }
 133
 134         wdt->mr &= ~AT91_WDT_WDV;
 135         wdt->mr |= AT91_WDT_SET_WDV(value);
 136
 137         /*
 138          * WDDIS has to be 0 when updating WDD/WDV. The datasheet states: When
 139          * setting the WDDIS bit, and while it is set, the fields WDV and WDD
 140          * must not be modified.
 141          * If the watchdog is enabled, then the timeout can be updated. Else,
 142          * wait that the user enables it.
 143          */
 144         if (wdt_enabled)
 145                 wdt_write(wdt, AT91_WDT_MR, wdt->mr & ~AT91_WDT_WDDIS);
 146
 147         wdd->timeout = timeout;
 148
 149         return 0;
 150 }
 151
 152 static const struct watchdog_info sama5d4_wdt_info = {
 153         .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
 154         .identity = "Atmel SAMA5D4 Watchdog",
 155 };
 156
 157 static const struct watchdog_ops sama5d4_wdt_ops = {
 158         .owner = THIS_MODULE,
 159         .start = sama5d4_wdt_start,
 160         .stop = sama5d4_wdt_stop,
 161         .ping = sama5d4_wdt_ping,
 162         .set_timeout = sama5d4_wdt_set_timeout,
 163 };
 164
 165 static irqreturn_t sama5d4_wdt_irq_handler(int irq, void *dev_id)
 166 {
 167         struct sama5d4_wdt *wdt = platform_get_drvdata(dev_id);
 168         u32 reg;
 169
 170         if (wdt->sam9x60_support)
 171                 reg = wdt_read(wdt, AT91_SAM9X60_ISR);
 172         else
 173                 reg = wdt_read(wdt, AT91_WDT_SR);
 174
 175         if (reg) {
 176                 pr_crit("Atmel Watchdog Software Reset\n");
 177                 emergency_restart();
 178                 pr_crit("Reboot didn't succeed\n");
 179         }
 180
 181         return IRQ_HANDLED;
 182 }
 183
 184 static int of_sama5d4_wdt_init(struct device_node *np, struct sama5d4_wdt *wdt)
 185 {
 186         const char *tmp;
 187
 188         if (wdt->sam9x60_support)
 189                 wdt->mr = AT91_SAM9X60_WDDIS;
 190         else
 191                 wdt->mr = AT91_WDT_WDDIS;
 192
 193         if (!of_property_read_string(np, "atmel,watchdog-type", &tmp) &&
 194             !strcmp(tmp, "software"))
 195                 wdt->need_irq = true;
 196
 197         if (of_property_read_bool(np, "atmel,idle-halt"))
 198                 wdt->mr |= AT91_WDT_WDIDLEHLT;
 199
 200         if (of_property_read_bool(np, "atmel,dbg-halt"))
 201                 wdt->mr |= AT91_WDT_WDDBGHLT;
 202
 203         return 0;
 204 }
 205
 206 static int sama5d4_wdt_init(struct sama5d4_wdt *wdt)
 207 {
 208         u32 reg, val;
 209
 210         val = WDT_SEC2TICKS(WDT_DEFAULT_TIMEOUT);
 211         /*
 212          * When booting and resuming, the bootloader may have changed the
 213          * watchdog configuration.
 214          * If the watchdog is already running, we can safely update it.
 215          * Else, we have to disable it properly.
 216          */
 217         if (!wdt_enabled) {
 218                 reg = wdt_read(wdt, AT91_WDT_MR);
 219                 if (wdt->sam9x60_support && (!(reg & AT91_SAM9X60_WDDIS)))
 220                         wdt_write_nosleep(wdt, AT91_WDT_MR,
 221                                           reg | AT91_SAM9X60_WDDIS);
 222                 else if (!wdt->sam9x60_support &&
 223                          (!(reg & AT91_WDT_WDDIS)))
 224                         wdt_write_nosleep(wdt, AT91_WDT_MR,
 225                                           reg | AT91_WDT_WDDIS);
 226         }
 227
 228         if (wdt->sam9x60_support) {
 229                 if (wdt->need_irq)
 230                         wdt->ir = AT91_SAM9X60_PERINT;
 231                 else
 232                         wdt->mr |= AT91_SAM9X60_PERIODRST;
 233
 234                 wdt_write(wdt, AT91_SAM9X60_IER, wdt->ir);
 235                 wdt_write(wdt, AT91_SAM9X60_WLR, AT91_SAM9X60_SET_COUNTER(val));
 236         } else {
 237                 wdt->mr |= AT91_WDT_SET_WDD(WDT_SEC2TICKS(MAX_WDT_TIMEOUT));
 238                 wdt->mr |= AT91_WDT_SET_WDV(val);
 239
 240                 if (wdt->need_irq)
 241                         wdt->mr |= AT91_WDT_WDFIEN;
 242                 else
 243                         wdt->mr |= AT91_WDT_WDRSTEN;
 244         }
 245
 246         wdt_write_nosleep(wdt, AT91_WDT_MR, wdt->mr);
 247
 248         return 0;
 249 }
 250
 251 static int sama5d4_wdt_probe(struct platform_device *pdev)
 252 {
 253         struct device *dev = &pdev->dev;
 254         struct watchdog_device *wdd;
 255         struct sama5d4_wdt *wdt;
 256         void __iomem *regs;
 257         u32 irq = 0;
 258         int ret;
 259
 260         wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
 261         if (!wdt)
 262                 return -ENOMEM;
 263
 264         wdd = &wdt->wdd;
 265         wdd->timeout = WDT_DEFAULT_TIMEOUT;
 266         wdd->info = &sama5d4_wdt_info;
 267         wdd->ops = &sama5d4_wdt_ops;
 268         wdd->min_timeout = MIN_WDT_TIMEOUT;
 269         wdd->max_timeout = MAX_WDT_TIMEOUT;
 270         wdt->last_ping = jiffies;
 271         wdt->sam9x60_support = of_device_is_compatible(dev->of_node,
 272                                                        "microchip,sam9x60-wdt");
 273
 274         watchdog_set_drvdata(wdd, wdt);
 275
 276         regs = devm_platform_ioremap_resource(pdev, 0);
 277         if (IS_ERR(regs))
 278                 return PTR_ERR(regs);
 279
 280         wdt->reg_base = regs;
 281
 282         ret = of_sama5d4_wdt_init(dev->of_node, wdt);
 283         if (ret)
 284                 return ret;
 285
 286         if (wdt->need_irq) {
 287                 irq = irq_of_parse_and_map(dev->of_node, 0);
 288                 if (!irq) {
 289                         dev_warn(dev, "failed to get IRQ from DT\n");
 290                         wdt->need_irq = false;
 291                 }
 292         }
 293
 294         if (wdt->need_irq) {
 295                 ret = devm_request_irq(dev, irq, sama5d4_wdt_irq_handler,
 296                                        IRQF_SHARED | IRQF_IRQPOLL |
 297                                        IRQF_NO_SUSPEND, pdev->name, pdev);
 298                 if (ret) {
 299                         dev_err(dev, "cannot register interrupt handler\n");
 300                         return ret;
 301                 }
 302         }
 303
 304         watchdog_init_timeout(wdd, wdt_timeout, dev);
 305
 306         ret = sama5d4_wdt_init(wdt);
 307         if (ret)
 308                 return ret;
 309
 310         watchdog_set_nowayout(wdd, nowayout);
 311
 312         watchdog_stop_on_unregister(wdd);
 313         ret = devm_watchdog_register_device(dev, wdd);
 314         if (ret)
 315                 return ret;
 316
 317         platform_set_drvdata(pdev, wdt);
 318
 319         dev_info(dev, "initialized (timeout = %d sec, nowayout = %d)\n",
 320                  wdd->timeout, nowayout);
 321
 322         return 0;
 323 }
 324
 325 static const struct of_device_id sama5d4_wdt_of_match[] = {
 326         {
 327                 .compatible = "atmel,sama5d4-wdt",
 328         },
 329         {
 330                 .compatible = "microchip,sam9x60-wdt",
 331         },
 332         { }
 333 };
 334 MODULE_DEVICE_TABLE(of, sama5d4_wdt_of_match);
 335
 336 #ifdef CONFIG_PM_SLEEP
 337 static int sama5d4_wdt_suspend_late(struct device *dev)
 338 {
 339         struct sama5d4_wdt *wdt = dev_get_drvdata(dev);
 340
 341         if (watchdog_active(&wdt->wdd))
 342                 sama5d4_wdt_stop(&wdt->wdd);
 343
 344         return 0;
 345 }
 346
 347 static int sama5d4_wdt_resume_early(struct device *dev)
 348 {
 349         struct sama5d4_wdt *wdt = dev_get_drvdata(dev);
 350
 351         /*
 352          * FIXME: writing MR also pings the watchdog which may not be desired.
 353          * This should only be done when the registers are lost on suspend but
 354          * there is no way to get this information right now.
 355          */
 356         sama5d4_wdt_init(wdt);
 357
 358         if (watchdog_active(&wdt->wdd))
 359                 sama5d4_wdt_start(&wdt->wdd);
 360
 361         return 0;
 362 }
 363 #endif
 364
 365 static const struct dev_pm_ops sama5d4_wdt_pm_ops = {
 366         SET_LATE_SYSTEM_SLEEP_PM_OPS(sama5d4_wdt_suspend_late,
 367                         sama5d4_wdt_resume_early)
 368 };
 369
 370 static struct platform_driver sama5d4_wdt_driver = {
 371         .probe          = sama5d4_wdt_probe,
 372         .driver         = {
 373                 .name   = "sama5d4_wdt",
 374                 .pm     = &sama5d4_wdt_pm_ops,
 375                 .of_match_table = sama5d4_wdt_of_match,
 376         }
 377 };
 378 module_platform_driver(sama5d4_wdt_driver);
 379
 380 MODULE_AUTHOR("Atmel Corporation");
 381 MODULE_DESCRIPTION("Atmel SAMA5D4 Watchdog Timer driver");
 382 MODULE_LICENSE("GPL v2");