drivers/watchdog/armada_37xx_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Watchdog driver for Marvell Armada 37xx SoCs
   4  *
   5  * Author: Marek Behun <marek.behun@nic.cz>
   6  */
   7
   8 #include <linux/clk.h>
   9 #include <linux/err.h>
  10 #include <linux/interrupt.h>
  11 #include <linux/io.h>
  12 #include <linux/kernel.h>
  13 #include <linux/mfd/syscon.h>
  14 #include <linux/module.h>
  15 #include <linux/moduleparam.h>
  16 #include <linux/of.h>
  17 #include <linux/of_device.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/regmap.h>
  20 #include <linux/types.h>
  21 #include <linux/watchdog.h>
  22
  23 /*
  24  * There are four counters that can be used for watchdog on Armada 37xx.
  25  * The addresses for counter control registers are register base plus ID*0x10,
  26  * where ID is 0, 1, 2 or 3.
  27  *
  28  * In this driver we use IDs 0 and 1. Counter ID 1 is used as watchdog counter,
  29  * while counter ID 0 is used to implement pinging the watchdog: counter ID 1 is
  30  * set to restart counting from initial value on counter ID 0 end count event.
  31  * Pinging is done by forcing immediate end count event on counter ID 0.
  32  * If only one counter was used, pinging would have to be implemented by
  33  * disabling and enabling the counter, leaving the system in a vulnerable state
  34  * for a (really) short period of time.
  35  *
  36  * Counters ID 2 and 3 are enabled by default even before U-Boot loads,
  37  * therefore this driver does not provide a way to use them, eg. by setting a
  38  * property in device tree.
  39  */
  40
  41 #define CNTR_ID_RETRIGGER               0
  42 #define CNTR_ID_WDOG                    1
  43
  44 /* relative to cpu_misc */
  45 #define WDT_TIMER_SELECT                0x64
  46 #define WDT_TIMER_SELECT_MASK           0xf
  47 #define WDT_TIMER_SELECT_VAL            BIT(CNTR_ID_WDOG)
  48
  49 /* relative to reg */
  50 #define CNTR_CTRL(id)                   ((id) * 0x10)
  51 #define CNTR_CTRL_ENABLE                0x0001
  52 #define CNTR_CTRL_ACTIVE                0x0002
  53 #define CNTR_CTRL_MODE_MASK             0x000c
  54 #define CNTR_CTRL_MODE_ONESHOT          0x0000
  55 #define CNTR_CTRL_MODE_HWSIG            0x000c
  56 #define CNTR_CTRL_TRIG_SRC_MASK         0x00f0
  57 #define CNTR_CTRL_TRIG_SRC_PREV_CNTR    0x0050
  58 #define CNTR_CTRL_PRESCALE_MASK         0xff00
  59 #define CNTR_CTRL_PRESCALE_MIN          2
  60 #define CNTR_CTRL_PRESCALE_SHIFT        8
  61
  62 #define CNTR_COUNT_LOW(id)              (CNTR_CTRL(id) + 0x4)
  63 #define CNTR_COUNT_HIGH(id)             (CNTR_CTRL(id) + 0x8)
  64
  65 #define WATCHDOG_TIMEOUT                120
  66
  67 static unsigned int timeout;
  68 module_param(timeout, int, 0);
  69 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds");
  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 struct armada_37xx_watchdog {
  77         struct watchdog_device wdt;
  78         struct regmap *cpu_misc;
  79         void __iomem *reg;
  80         u64 timeout; /* in clock ticks */
  81         unsigned long clk_rate;
  82         struct clk *clk;
  83 };
  84
  85 static u64 get_counter_value(struct armada_37xx_watchdog *dev, int id)
  86 {
  87         u64 val;
  88
  89         /*
  90          * when low is read, high is latched into flip-flops so that it can be
  91          * read consistently without using software debouncing
  92          */
  93         val = readl(dev->reg + CNTR_COUNT_LOW(id));
  94         val |= ((u64)readl(dev->reg + CNTR_COUNT_HIGH(id))) << 32;
  95
  96         return val;
  97 }
  98
  99 static void set_counter_value(struct armada_37xx_watchdog *dev, int id, u64 val)
 100 {
 101         writel(val & 0xffffffff, dev->reg + CNTR_COUNT_LOW(id));
 102         writel(val >> 32, dev->reg + CNTR_COUNT_HIGH(id));
 103 }
 104
 105 static void counter_enable(struct armada_37xx_watchdog *dev, int id)
 106 {
 107         u32 reg;
 108
 109         reg = readl(dev->reg + CNTR_CTRL(id));
 110         reg |= CNTR_CTRL_ENABLE;
 111         writel(reg, dev->reg + CNTR_CTRL(id));
 112 }
 113
 114 static void counter_disable(struct armada_37xx_watchdog *dev, int id)
 115 {
 116         u32 reg;
 117
 118         reg = readl(dev->reg + CNTR_CTRL(id));
 119         reg &= ~CNTR_CTRL_ENABLE;
 120         writel(reg, dev->reg + CNTR_CTRL(id));
 121 }
 122
 123 static void init_counter(struct armada_37xx_watchdog *dev, int id, u32 mode,
 124                          u32 trig_src)
 125 {
 126         u32 reg;
 127
 128         reg = readl(dev->reg + CNTR_CTRL(id));
 129
 130         reg &= ~(CNTR_CTRL_MODE_MASK | CNTR_CTRL_PRESCALE_MASK |
 131                  CNTR_CTRL_TRIG_SRC_MASK);
 132
 133         /* set mode */
 134         reg |= mode & CNTR_CTRL_MODE_MASK;
 135
 136         /* set prescaler to the min value */
 137         reg |= CNTR_CTRL_PRESCALE_MIN << CNTR_CTRL_PRESCALE_SHIFT;
 138
 139         /* set trigger source */
 140         reg |= trig_src & CNTR_CTRL_TRIG_SRC_MASK;
 141
 142         writel(reg, dev->reg + CNTR_CTRL(id));
 143 }
 144
 145 static int armada_37xx_wdt_ping(struct watchdog_device *wdt)
 146 {
 147         struct armada_37xx_watchdog *dev = watchdog_get_drvdata(wdt);
 148
 149         /* counter 1 is retriggered by forcing end count on counter 0 */
 150         counter_disable(dev, CNTR_ID_RETRIGGER);
 151         counter_enable(dev, CNTR_ID_RETRIGGER);
 152
 153         return 0;
 154 }
 155
 156 static unsigned int armada_37xx_wdt_get_timeleft(struct watchdog_device *wdt)
 157 {
 158         struct armada_37xx_watchdog *dev = watchdog_get_drvdata(wdt);
 159         u64 res;
 160
 161         res = get_counter_value(dev, CNTR_ID_WDOG) * CNTR_CTRL_PRESCALE_MIN;
 162         do_div(res, dev->clk_rate);
 163
 164         return res;
 165 }
 166
 167 static int armada_37xx_wdt_set_timeout(struct watchdog_device *wdt,
 168                                        unsigned int timeout)
 169 {
 170         struct armada_37xx_watchdog *dev = watchdog_get_drvdata(wdt);
 171
 172         wdt->timeout = timeout;
 173
 174         /*
 175          * Compute the timeout in clock rate. We use smallest possible
 176          * prescaler, which divides the clock rate by 2
 177          * (CNTR_CTRL_PRESCALE_MIN).
 178          */
 179         dev->timeout = (u64)dev->clk_rate * timeout;
 180         do_div(dev->timeout, CNTR_CTRL_PRESCALE_MIN);
 181
 182         return 0;
 183 }
 184
 185 static bool armada_37xx_wdt_is_running(struct armada_37xx_watchdog *dev)
 186 {
 187         u32 reg;
 188
 189         regmap_read(dev->cpu_misc, WDT_TIMER_SELECT, &reg);
 190         if ((reg & WDT_TIMER_SELECT_MASK) != WDT_TIMER_SELECT_VAL)
 191                 return false;
 192
 193         reg = readl(dev->reg + CNTR_CTRL(CNTR_ID_WDOG));
 194         return !!(reg & CNTR_CTRL_ACTIVE);
 195 }
 196
 197 static int armada_37xx_wdt_start(struct watchdog_device *wdt)
 198 {
 199         struct armada_37xx_watchdog *dev = watchdog_get_drvdata(wdt);
 200
 201         /* select counter 1 as watchdog counter */
 202         regmap_write(dev->cpu_misc, WDT_TIMER_SELECT, WDT_TIMER_SELECT_VAL);
 203
 204         /* init counter 0 as retrigger counter for counter 1 */
 205         init_counter(dev, CNTR_ID_RETRIGGER, CNTR_CTRL_MODE_ONESHOT, 0);
 206         set_counter_value(dev, CNTR_ID_RETRIGGER, 0);
 207
 208         /* init counter 1 to be retriggerable by counter 0 end count */
 209         init_counter(dev, CNTR_ID_WDOG, CNTR_CTRL_MODE_HWSIG,
 210                      CNTR_CTRL_TRIG_SRC_PREV_CNTR);
 211         set_counter_value(dev, CNTR_ID_WDOG, dev->timeout);
 212
 213         /* enable counter 1 */
 214         counter_enable(dev, CNTR_ID_WDOG);
 215
 216         /* start counter 1 by forcing immediate end count on counter 0 */
 217         counter_enable(dev, CNTR_ID_RETRIGGER);
 218
 219         return 0;
 220 }
 221
 222 static int armada_37xx_wdt_stop(struct watchdog_device *wdt)
 223 {
 224         struct armada_37xx_watchdog *dev = watchdog_get_drvdata(wdt);
 225
 226         counter_disable(dev, CNTR_ID_WDOG);
 227         counter_disable(dev, CNTR_ID_RETRIGGER);
 228         regmap_write(dev->cpu_misc, WDT_TIMER_SELECT, 0);
 229
 230         return 0;
 231 }
 232
 233 static const struct watchdog_info armada_37xx_wdt_info = {
 234         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 235         .identity = "Armada 37xx Watchdog",
 236 };
 237
 238 static const struct watchdog_ops armada_37xx_wdt_ops = {
 239         .owner = THIS_MODULE,
 240         .start = armada_37xx_wdt_start,
 241         .stop = armada_37xx_wdt_stop,
 242         .ping = armada_37xx_wdt_ping,
 243         .set_timeout = armada_37xx_wdt_set_timeout,
 244         .get_timeleft = armada_37xx_wdt_get_timeleft,
 245 };
 246
 247 static void armada_clk_disable_unprepare(void *data)
 248 {
 249         clk_disable_unprepare(data);
 250 }
 251
 252 static int armada_37xx_wdt_probe(struct platform_device *pdev)
 253 {
 254         struct armada_37xx_watchdog *dev;
 255         struct resource *res;
 256         struct regmap *regmap;
 257         int ret;
 258
 259         dev = devm_kzalloc(&pdev->dev, sizeof(struct armada_37xx_watchdog),
 260                            GFP_KERNEL);
 261         if (!dev)
 262                 return -ENOMEM;
 263
 264         dev->wdt.info = &armada_37xx_wdt_info;
 265         dev->wdt.ops = &armada_37xx_wdt_ops;
 266
 267         regmap = syscon_regmap_lookup_by_phandle(pdev->dev.of_node,
 268                                                  "marvell,system-controller");
 269         if (IS_ERR(regmap))
 270                 return PTR_ERR(regmap);
 271         dev->cpu_misc = regmap;
 272
 273         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 274         if (!res)
 275                 return -ENODEV;
 276         dev->reg = devm_ioremap(&pdev->dev, res->start, resource_size(res));
 277
 278         /* init clock */
 279         dev->clk = devm_clk_get(&pdev->dev, NULL);
 280         if (IS_ERR(dev->clk))
 281                 return PTR_ERR(dev->clk);
 282
 283         ret = clk_prepare_enable(dev->clk);
 284         if (ret)
 285                 return ret;
 286         ret = devm_add_action_or_reset(&pdev->dev,
 287                                        armada_clk_disable_unprepare, dev->clk);
 288         if (ret)
 289                 return ret;
 290
 291         dev->clk_rate = clk_get_rate(dev->clk);
 292         if (!dev->clk_rate)
 293                 return -EINVAL;
 294
 295         /*
 296          * Since the timeout in seconds is given as 32 bit unsigned int, and
 297          * the counters hold 64 bit values, even after multiplication by clock
 298          * rate the counter can hold timeout of UINT_MAX seconds.
 299          */
 300         dev->wdt.min_timeout = 1;
 301         dev->wdt.max_timeout = UINT_MAX;
 302         dev->wdt.parent = &pdev->dev;
 303
 304         /* default value, possibly override by module parameter or dtb */
 305         dev->wdt.timeout = WATCHDOG_TIMEOUT;
 306         watchdog_init_timeout(&dev->wdt, timeout, &pdev->dev);
 307
 308         platform_set_drvdata(pdev, &dev->wdt);
 309         watchdog_set_drvdata(&dev->wdt, dev);
 310
 311         armada_37xx_wdt_set_timeout(&dev->wdt, dev->wdt.timeout);
 312
 313         if (armada_37xx_wdt_is_running(dev))
 314                 set_bit(WDOG_HW_RUNNING, &dev->wdt.status);
 315
 316         watchdog_set_nowayout(&dev->wdt, nowayout);
 317         watchdog_stop_on_reboot(&dev->wdt);
 318         ret = devm_watchdog_register_device(&pdev->dev, &dev->wdt);
 319         if (ret)
 320                 return ret;
 321
 322         dev_info(&pdev->dev, "Initial timeout %d sec%s\n",
 323                  dev->wdt.timeout, nowayout ? ", nowayout" : "");
 324
 325         return 0;
 326 }
 327
 328 static int __maybe_unused armada_37xx_wdt_suspend(struct device *dev)
 329 {
 330         struct watchdog_device *wdt = dev_get_drvdata(dev);
 331
 332         return armada_37xx_wdt_stop(wdt);
 333 }
 334
 335 static int __maybe_unused armada_37xx_wdt_resume(struct device *dev)
 336 {
 337         struct watchdog_device *wdt = dev_get_drvdata(dev);
 338
 339         if (watchdog_active(wdt))
 340                 return armada_37xx_wdt_start(wdt);
 341
 342         return 0;
 343 }
 344
 345 static const struct dev_pm_ops armada_37xx_wdt_dev_pm_ops = {
 346         SET_SYSTEM_SLEEP_PM_OPS(armada_37xx_wdt_suspend,
 347                                 armada_37xx_wdt_resume)
 348 };
 349
 350 #ifdef CONFIG_OF
 351 static const struct of_device_id armada_37xx_wdt_match[] = {
 352         { .compatible = "marvell,armada-3700-wdt", },
 353         {},
 354 };
 355 MODULE_DEVICE_TABLE(of, armada_37xx_wdt_match);
 356 #endif
 357
 358 static struct platform_driver armada_37xx_wdt_driver = {
 359         .probe          = armada_37xx_wdt_probe,
 360         .driver         = {
 361                 .name   = "armada_37xx_wdt",
 362                 .of_match_table = of_match_ptr(armada_37xx_wdt_match),
 363                 .pm = &armada_37xx_wdt_dev_pm_ops,
 364         },
 365 };
 366
 367 module_platform_driver(armada_37xx_wdt_driver);
 368
 369 MODULE_AUTHOR("Marek Behun <marek.behun@nic.cz>");
 370 MODULE_DESCRIPTION("Armada 37xx CPU Watchdog");
 371
 372 MODULE_LICENSE("GPL v2");
 373 MODULE_ALIAS("platform:armada_37xx_wdt");