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