LXR linux/drivers/watchdog/dw

   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
  49static bool nowayout = WATCHDOG_NOWAYOUT;
  50module_param(nowayout, bool, 0);
  51MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
  52                 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  53
  54struct dw_wdt {
  55        void __iomem            *regs;
  56        struct clk              *clk;
  57        unsigned long           rate;
  58        struct notifier_block   restart_handler;
  59        struct watchdog_device  wdd;
  60};
  61
  62#define to_dw_wdt(wdd)  container_of(wdd, struct dw_wdt, wdd)
  63
  64static inline int dw_wdt_is_enabled(struct dw_wdt *dw_wdt)
  65{
  66        return readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET) &
  67                WDOG_CONTROL_REG_WDT_EN_MASK;
  68}
  69
  70static inline int dw_wdt_top_in_seconds(struct dw_wdt *dw_wdt, unsigned top)
  71{
  72        /*
  73         * There are 16 possible timeout values in 0..15 where the number of
  74         * cycles is 2 ^ (16 + i) and the watchdog counts down.
  75         */
  76        return (1U << (16 + top)) / dw_wdt->rate;
  77}
  78
  79static int dw_wdt_get_top(struct dw_wdt *dw_wdt)
  80{
  81        int top = readl(dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET) & 0xF;
  82
  83        return dw_wdt_top_in_seconds(dw_wdt, top);
  84}
  85
  86static int dw_wdt_ping(struct watchdog_device *wdd)
  87{
  88        struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
  89
  90        writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt->regs +
  91               WDOG_COUNTER_RESTART_REG_OFFSET);
  92
  93        return 0;
  94}
  95
  96static int dw_wdt_set_timeout(struct watchdog_device *wdd, unsigned int top_s)
  97{
  98        struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
  99        int i, top_val = DW_WDT_MAX_TOP;
 100
 101        /*
 102         * Iterate over the timeout values until we find the closest match. We
 103         * always look for >=.
 104         */
 105        for (i = 0; i <= DW_WDT_MAX_TOP; ++i)
 106                if (dw_wdt_top_in_seconds(dw_wdt, i) >= top_s) {
 107                        top_val = i;
 108                        break;
 109                }
 110
 111        /*
 112         * Set the new value in the watchdog.  Some versions of dw_wdt
 113         * have have TOPINIT in the TIMEOUT_RANGE register (as per
 114         * CP_WDT_DUAL_TOP in WDT_COMP_PARAMS_1).  On those we
 115         * effectively get a pat of the watchdog right here.
 116         */
 117        writel(top_val | top_val << WDOG_TIMEOUT_RANGE_TOPINIT_SHIFT,
 118               dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
 119
 120        wdd->timeout = dw_wdt_top_in_seconds(dw_wdt, top_val);
 121
 122        return 0;
 123}
 124
 125static int dw_wdt_start(struct watchdog_device *wdd)
 126{
 127        struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
 128
 129        dw_wdt_set_timeout(wdd, wdd->timeout);
 130
 131        set_bit(WDOG_HW_RUNNING, &wdd->status);
 132
 133        writel(WDOG_CONTROL_REG_WDT_EN_MASK,
 134               dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
 135
 136        return 0;
 137}
 138
 139static int dw_wdt_restart_handle(struct notifier_block *this,
 140                                 unsigned long mode, void *cmd)
 141{
 142        struct dw_wdt *dw_wdt;
 143        u32 val;
 144
 145        dw_wdt = container_of(this, struct dw_wdt, restart_handler);
 146
 147        writel(0, dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
 148        val = readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
 149        if (val & WDOG_CONTROL_REG_WDT_EN_MASK)
 150                writel(WDOG_COUNTER_RESTART_KICK_VALUE,
 151                       dw_wdt->regs + WDOG_COUNTER_RESTART_REG_OFFSET);
 152        else
 153                writel(WDOG_CONTROL_REG_WDT_EN_MASK,
 154                       dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
 155
 156        /* wait for reset to assert... */
 157        mdelay(500);
 158
 159        return NOTIFY_DONE;
 160}
 161
 162static unsigned int dw_wdt_get_timeleft(struct watchdog_device *wdd)
 163{
 164        struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
 165
 166        return readl(dw_wdt->regs + WDOG_CURRENT_COUNT_REG_OFFSET) /
 167                dw_wdt->rate;
 168}
 169
 170static const struct watchdog_info dw_wdt_ident = {
 171        .options        = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
 172                          WDIOF_MAGICCLOSE,
 173        .identity       = "Synopsys DesignWare Watchdog",
 174};
 175
 176static const struct watchdog_ops dw_wdt_ops = {
 177        .owner          = THIS_MODULE,
 178        .start          = dw_wdt_start,
 179        .ping           = dw_wdt_ping,
 180        .set_timeout    = dw_wdt_set_timeout,
 181        .get_timeleft   = dw_wdt_get_timeleft,
 182};
 183
 184#ifdef CONFIG_PM_SLEEP
 185static int dw_wdt_suspend(struct device *dev)
 186{
 187        struct dw_wdt *dw_wdt = dev_get_drvdata(dev);
 188
 189        clk_disable_unprepare(dw_wdt->clk);
 190
 191        return 0;
 192}
 193
 194static int dw_wdt_resume(struct device *dev)
 195{
 196        struct dw_wdt *dw_wdt = dev_get_drvdata(dev);
 197        int err = clk_prepare_enable(dw_wdt->clk);
 198
 199        if (err)
 200                return err;
 201
 202        dw_wdt_ping(&dw_wdt->wdd);
 203
 204        return 0;
 205}
 206#endif /* CONFIG_PM_SLEEP */
 207
 208static SIMPLE_DEV_PM_OPS(dw_wdt_pm_ops, dw_wdt_suspend, dw_wdt_resume);
 209
 210static int dw_wdt_drv_probe(struct platform_device *pdev)
 211{
 212        struct device *dev = &pdev->dev;
 213        struct watchdog_device *wdd;
 214        struct dw_wdt *dw_wdt;
 215        struct resource *mem;
 216        int ret;
 217
 218        dw_wdt = devm_kzalloc(dev, sizeof(*dw_wdt), GFP_KERNEL);
 219        if (!dw_wdt)
 220                return -ENOMEM;
 221
 222        mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 223        dw_wdt->regs = devm_ioremap_resource(dev, mem);
 224        if (IS_ERR(dw_wdt->regs))
 225                return PTR_ERR(dw_wdt->regs);
 226
 227        dw_wdt->clk = devm_clk_get(dev, NULL);
 228        if (IS_ERR(dw_wdt->clk))
 229                return PTR_ERR(dw_wdt->clk);
 230
 231        ret = clk_prepare_enable(dw_wdt->clk);
 232        if (ret)
 233                return ret;
 234
 235        dw_wdt->rate = clk_get_rate(dw_wdt->clk);
 236        if (dw_wdt->rate == 0) {
 237                ret = -EINVAL;
 238                goto out_disable_clk;
 239        }
 240
 241        wdd = &dw_wdt->wdd;
 242        wdd->info = &dw_wdt_ident;
 243        wdd->ops = &dw_wdt_ops;
 244        wdd->min_timeout = 1;
 245        wdd->max_hw_heartbeat_ms =
 246                dw_wdt_top_in_seconds(dw_wdt, DW_WDT_MAX_TOP) * 1000;
 247        wdd->parent = dev;
 248
 249        watchdog_set_drvdata(wdd, dw_wdt);
 250        watchdog_set_nowayout(wdd, nowayout);
 251        watchdog_init_timeout(wdd, 0, dev);
 252
 253        /*
 254         * If the watchdog is already running, use its already configured
 255         * timeout. Otherwise use the default or the value provided through
 256         * devicetree.
 257         */
 258        if (dw_wdt_is_enabled(dw_wdt)) {
 259                wdd->timeout = dw_wdt_get_top(dw_wdt);
 260                set_bit(WDOG_HW_RUNNING, &wdd->status);
 261        } else {
 262                wdd->timeout = DW_WDT_DEFAULT_SECONDS;
 263                watchdog_init_timeout(wdd, 0, dev);
 264        }
 265
 266        platform_set_drvdata(pdev, dw_wdt);
 267
 268        ret = watchdog_register_device(wdd);
 269        if (ret)
 270                goto out_disable_clk;
 271
 272        dw_wdt->restart_handler.notifier_call = dw_wdt_restart_handle;
 273        dw_wdt->restart_handler.priority = 128;
 274        ret = register_restart_handler(&dw_wdt->restart_handler);
 275        if (ret)
 276                pr_warn("cannot register restart handler\n");
 277
 278        return 0;
 279
 280out_disable_clk:
 281        clk_disable_unprepare(dw_wdt->clk);
 282        return ret;
 283}
 284
 285static int dw_wdt_drv_remove(struct platform_device *pdev)
 286{
 287        struct dw_wdt *dw_wdt = platform_get_drvdata(pdev);
 288
 289        unregister_restart_handler(&dw_wdt->restart_handler);
 290        watchdog_unregister_device(&dw_wdt->wdd);
 291        clk_disable_unprepare(dw_wdt->clk);
 292
 293        return 0;
 294}
 295
 296#ifdef CONFIG_OF
 297static const struct of_device_id dw_wdt_of_match[] = {
 298        { .compatible = "snps,dw-wdt", },
 299        { /* sentinel */ }
 300};
 301MODULE_DEVICE_TABLE(of, dw_wdt_of_match);
 302#endif
 303
 304static struct platform_driver dw_wdt_driver = {
 305        .probe          = dw_wdt_drv_probe,
 306        .remove         = dw_wdt_drv_remove,
 307        .driver         = {
 308                .name   = "dw_wdt",
 309                .of_match_table = of_match_ptr(dw_wdt_of_match),
 310                .pm     = &dw_wdt_pm_ops,
 311        },
 312};
 313
 314module_platform_driver(dw_wdt_driver);
 315
 316MODULE_AUTHOR("Jamie Iles");
 317MODULE_DESCRIPTION("Synopsys DesignWare Watchdog Driver");
 318MODULE_LICENSE("GPL");
 319