drivers/watchdog/dw_wdt.c

   1 /*
   2  * Copyright 2010-2011 Picochip Ltd., Jamie Iles
   3  * http://www.picochip.com
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License
   7  * as published by the Free Software Foundation; either version
   8  * 2 of the License, or (at your option) any later version.
   9  *
  10  * This file implements a driver for the Synopsys DesignWare watchdog device
  11  * in the many subsystems. The watchdog has 16 different timeout periods
  12  * and these are a function of the input clock frequency.
  13  *
  14  * The DesignWare watchdog cannot be stopped once it has been started so we
  15  * do not implement a stop function. The watchdog core will continue to send
  16  * heartbeat requests after the watchdog device has been closed.
  17  */
  18
  19 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  20
  21 #include <linux/bitops.h>
  22 #include <linux/clk.h>
  23 #include <linux/delay.h>
  24 #include <linux/err.h>
  25 #include <linux/io.h>
  26 #include <linux/kernel.h>
  27 #include <linux/module.h>
  28 #include <linux/moduleparam.h>
  29 #include <linux/notifier.h>
  30 #include <linux/of.h>
  31 #include <linux/pm.h>
  32 #include <linux/platform_device.h>
  33 #include <linux/reboot.h>
  34 #include <linux/watchdog.h>
  35
  36 #define WDOG_CONTROL_REG_OFFSET             0x00
  37 #define WDOG_CONTROL_REG_WDT_EN_MASK        0x01
  38 #define WDOG_TIMEOUT_RANGE_REG_OFFSET       0x04
  39 #define WDOG_TIMEOUT_RANGE_TOPINIT_SHIFT    4
  40 #define WDOG_CURRENT_COUNT_REG_OFFSET       0x08
  41 #define WDOG_COUNTER_RESTART_REG_OFFSET     0x0c
  42 #define WDOG_COUNTER_RESTART_KICK_VALUE     0x76
  43
  44 /* The maximum TOP (timeout period) value that can be set in the watchdog. */
  45 #define DW_WDT_MAX_TOP          15
  46
  47 #define DW_WDT_DEFAULT_SECONDS  30
  48
  49 static bool nowayout = WATCHDOG_NOWAYOUT;
  50 module_param(nowayout, bool, 0);
  51 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
  52                  "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  53
  54 struct dw_wdt {
  55         void __iomem            *regs;
  56         struct clk              *clk;
  57         struct notifier_block   restart_handler;
  58         struct watchdog_device  wdd;
  59 };
  60
  61 #define to_dw_wdt(wdd)  container_of(wdd, struct dw_wdt, wdd)
  62
  63 static inline int dw_wdt_is_enabled(struct dw_wdt *dw_wdt)
  64 {
  65         return readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET) &
  66                 WDOG_CONTROL_REG_WDT_EN_MASK;
  67 }
  68
  69 static inline int dw_wdt_top_in_seconds(struct dw_wdt *dw_wdt, unsigned top)
  70 {
  71         /*
  72          * There are 16 possible timeout values in 0..15 where the number of
  73          * cycles is 2 ^ (16 + i) and the watchdog counts down.
  74          */
  75         return (1U << (16 + top)) / clk_get_rate(dw_wdt->clk);
  76 }
  77
  78 static int dw_wdt_get_top(struct dw_wdt *dw_wdt)
  79 {
  80         int top = readl(dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET) & 0xF;
  81
  82         return dw_wdt_top_in_seconds(dw_wdt, top);
  83 }
  84
  85 static int dw_wdt_ping(struct watchdog_device *wdd)
  86 {
  87         struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
  88
  89         writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt->regs +
  90                WDOG_COUNTER_RESTART_REG_OFFSET);
  91
  92         return 0;
  93 }
  94
  95 static int dw_wdt_set_timeout(struct watchdog_device *wdd, unsigned int top_s)
  96 {
  97         struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
  98         int i, top_val = DW_WDT_MAX_TOP;
  99
 100         /*
 101          * Iterate over the timeout values until we find the closest match. We
 102          * always look for >=.
 103          */
 104         for (i = 0; i <= DW_WDT_MAX_TOP; ++i)
 105                 if (dw_wdt_top_in_seconds(dw_wdt, i) >= top_s) {
 106                         top_val = i;
 107                         break;
 108                 }
 109
 110         /*
 111          * Set the new value in the watchdog.  Some versions of dw_wdt
 112          * have have TOPINIT in the TIMEOUT_RANGE register (as per
 113          * CP_WDT_DUAL_TOP in WDT_COMP_PARAMS_1).  On those we
 114          * effectively get a pat of the watchdog right here.
 115          */
 116         writel(top_val | top_val << WDOG_TIMEOUT_RANGE_TOPINIT_SHIFT,
 117                dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
 118
 119         wdd->timeout = dw_wdt_top_in_seconds(dw_wdt, top_val);
 120
 121         return 0;
 122 }
 123
 124 static int dw_wdt_start(struct watchdog_device *wdd)
 125 {
 126         struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
 127
 128         dw_wdt_set_timeout(wdd, wdd->timeout);
 129
 130         set_bit(WDOG_HW_RUNNING, &wdd->status);
 131
 132         writel(WDOG_CONTROL_REG_WDT_EN_MASK,
 133                dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
 134
 135         return 0;
 136 }
 137
 138 static int dw_wdt_restart_handle(struct notifier_block *this,
 139                                  unsigned long mode, void *cmd)
 140 {
 141         struct dw_wdt *dw_wdt;
 142         u32 val;
 143
 144         dw_wdt = container_of(this, struct dw_wdt, restart_handler);
 145
 146         writel(0, dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
 147         val = readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
 148         if (val & WDOG_CONTROL_REG_WDT_EN_MASK)
 149                 writel(WDOG_COUNTER_RESTART_KICK_VALUE,
 150                        dw_wdt->regs + WDOG_COUNTER_RESTART_REG_OFFSET);
 151         else
 152                 writel(WDOG_CONTROL_REG_WDT_EN_MASK,
 153                        dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
 154
 155         /* wait for reset to assert... */
 156         mdelay(500);
 157
 158         return NOTIFY_DONE;
 159 }
 160
 161 static unsigned int dw_wdt_get_timeleft(struct watchdog_device *wdd)
 162 {
 163         struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
 164
 165         return readl(dw_wdt->regs + WDOG_CURRENT_COUNT_REG_OFFSET) /
 166                 clk_get_rate(dw_wdt->clk);
 167 }
 168
 169 static const struct watchdog_info dw_wdt_ident = {
 170         .options        = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
 171                           WDIOF_MAGICCLOSE,
 172         .identity       = "Synopsys DesignWare Watchdog",
 173 };
 174
 175 static const struct watchdog_ops dw_wdt_ops = {
 176         .owner          = THIS_MODULE,
 177         .start          = dw_wdt_start,
 178         .ping           = dw_wdt_ping,
 179         .set_timeout    = dw_wdt_set_timeout,
 180         .get_timeleft   = dw_wdt_get_timeleft,
 181 };
 182
 183 #ifdef CONFIG_PM_SLEEP
 184 static int dw_wdt_suspend(struct device *dev)
 185 {
 186         struct dw_wdt *dw_wdt = dev_get_drvdata(dev);
 187
 188         clk_disable_unprepare(dw_wdt->clk);
 189
 190         return 0;
 191 }
 192
 193 static int dw_wdt_resume(struct device *dev)
 194 {
 195         struct dw_wdt *dw_wdt = dev_get_drvdata(dev);
 196         int err = clk_prepare_enable(dw_wdt->clk);
 197
 198         if (err)
 199                 return err;
 200
 201         dw_wdt_ping(&dw_wdt->wdd);
 202
 203         return 0;
 204 }
 205 #endif /* CONFIG_PM_SLEEP */
 206
 207 static SIMPLE_DEV_PM_OPS(dw_wdt_pm_ops, dw_wdt_suspend, dw_wdt_resume);
 208
 209 static int dw_wdt_drv_probe(struct platform_device *pdev)
 210 {
 211         struct device *dev = &pdev->dev;
 212         struct watchdog_device *wdd;
 213         struct dw_wdt *dw_wdt;
 214         struct resource *mem;
 215         int ret;
 216
 217         dw_wdt = devm_kzalloc(dev, sizeof(*dw_wdt), GFP_KERNEL);
 218         if (!dw_wdt)
 219                 return -ENOMEM;
 220
 221         mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 222         dw_wdt->regs = devm_ioremap_resource(dev, mem);
 223         if (IS_ERR(dw_wdt->regs))
 224                 return PTR_ERR(dw_wdt->regs);
 225
 226         dw_wdt->clk = devm_clk_get(dev, NULL);
 227         if (IS_ERR(dw_wdt->clk))
 228                 return PTR_ERR(dw_wdt->clk);
 229
 230         ret = clk_prepare_enable(dw_wdt->clk);
 231         if (ret)
 232                 return ret;
 233
 234         wdd = &dw_wdt->wdd;
 235         wdd->info = &dw_wdt_ident;
 236         wdd->ops = &dw_wdt_ops;
 237         wdd->min_timeout = 1;
 238         wdd->max_hw_heartbeat_ms =
 239                 dw_wdt_top_in_seconds(dw_wdt, DW_WDT_MAX_TOP) * 1000;
 240         wdd->parent = dev;
 241
 242         watchdog_set_drvdata(wdd, dw_wdt);
 243         watchdog_set_nowayout(wdd, nowayout);
 244         watchdog_init_timeout(wdd, 0, dev);
 245
 246         /*
 247          * If the watchdog is already running, use its already configured
 248          * timeout. Otherwise use the default or the value provided through
 249          * devicetree.
 250          */
 251         if (dw_wdt_is_enabled(dw_wdt)) {
 252                 wdd->timeout = dw_wdt_get_top(dw_wdt);
 253                 set_bit(WDOG_HW_RUNNING, &wdd->status);
 254         } else {
 255                 wdd->timeout = DW_WDT_DEFAULT_SECONDS;
 256                 watchdog_init_timeout(wdd, 0, dev);
 257         }
 258
 259         platform_set_drvdata(pdev, dw_wdt);
 260
 261         ret = watchdog_register_device(wdd);
 262         if (ret)
 263                 goto out_disable_clk;
 264
 265         dw_wdt->restart_handler.notifier_call = dw_wdt_restart_handle;
 266         dw_wdt->restart_handler.priority = 128;
 267         ret = register_restart_handler(&dw_wdt->restart_handler);
 268         if (ret)
 269                 pr_warn("cannot register restart handler\n");
 270
 271         return 0;
 272
 273 out_disable_clk:
 274         clk_disable_unprepare(dw_wdt->clk);
 275         return ret;
 276 }
 277
 278 static int dw_wdt_drv_remove(struct platform_device *pdev)
 279 {
 280         struct dw_wdt *dw_wdt = platform_get_drvdata(pdev);
 281
 282         unregister_restart_handler(&dw_wdt->restart_handler);
 283         watchdog_unregister_device(&dw_wdt->wdd);
 284         clk_disable_unprepare(dw_wdt->clk);
 285
 286         return 0;
 287 }
 288
 289 #ifdef CONFIG_OF
 290 static const struct of_device_id dw_wdt_of_match[] = {
 291         { .compatible = "snps,dw-wdt", },
 292         { /* sentinel */ }
 293 };
 294 MODULE_DEVICE_TABLE(of, dw_wdt_of_match);
 295 #endif
 296
 297 static struct platform_driver dw_wdt_driver = {
 298         .probe          = dw_wdt_drv_probe,
 299         .remove         = dw_wdt_drv_remove,
 300         .driver         = {
 301                 .name   = "dw_wdt",
 302                 .of_match_table = of_match_ptr(dw_wdt_of_match),
 303                 .pm     = &dw_wdt_pm_ops,
 304         },
 305 };
 306
 307 module_platform_driver(dw_wdt_driver);
 308
 309 MODULE_AUTHOR("Jamie Iles");
 310 MODULE_DESCRIPTION("Synopsys DesignWare Watchdog Driver");
 311 MODULE_LICENSE("GPL");