linux/drivers/watchdog/tangox_wdt.c
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   1/*
   2 *  Copyright (C) 2015 Mans Rullgard <mans@mansr.com>
   3 *  SMP86xx/SMP87xx Watchdog driver
   4 *
   5 *  This program is free software; you can redistribute it and/or modify it
   6 *  under  the terms of the GNU General  Public License as published by the
   7 *  Free Software Foundation;  either version 2 of the License, or (at your
   8 *  option) any later version.
   9 */
  10
  11#include <linux/bitops.h>
  12#include <linux/clk.h>
  13#include <linux/delay.h>
  14#include <linux/io.h>
  15#include <linux/kernel.h>
  16#include <linux/module.h>
  17#include <linux/moduleparam.h>
  18#include <linux/notifier.h>
  19#include <linux/platform_device.h>
  20#include <linux/reboot.h>
  21#include <linux/watchdog.h>
  22
  23#define DEFAULT_TIMEOUT 30
  24
  25static bool nowayout = WATCHDOG_NOWAYOUT;
  26module_param(nowayout, bool, 0);
  27MODULE_PARM_DESC(nowayout,
  28                 "Watchdog cannot be stopped once started (default="
  29                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  30
  31static unsigned int timeout;
  32module_param(timeout, int, 0);
  33MODULE_PARM_DESC(timeout, "Watchdog timeout");
  34
  35/*
  36 * Counter counts down from programmed value.  Reset asserts when
  37 * the counter reaches 1.
  38 */
  39#define WD_COUNTER              0
  40
  41#define WD_CONFIG               4
  42#define WD_CONFIG_XTAL_IN       BIT(0)
  43#define WD_CONFIG_DISABLE       BIT(31)
  44
  45struct tangox_wdt_device {
  46        struct watchdog_device wdt;
  47        void __iomem *base;
  48        unsigned long clk_rate;
  49        struct clk *clk;
  50        struct notifier_block restart;
  51};
  52
  53static int tangox_wdt_set_timeout(struct watchdog_device *wdt,
  54                                  unsigned int new_timeout)
  55{
  56        wdt->timeout = new_timeout;
  57
  58        return 0;
  59}
  60
  61static int tangox_wdt_start(struct watchdog_device *wdt)
  62{
  63        struct tangox_wdt_device *dev = watchdog_get_drvdata(wdt);
  64        u32 ticks;
  65
  66        ticks = 1 + wdt->timeout * dev->clk_rate;
  67        writel(ticks, dev->base + WD_COUNTER);
  68
  69        return 0;
  70}
  71
  72static int tangox_wdt_stop(struct watchdog_device *wdt)
  73{
  74        struct tangox_wdt_device *dev = watchdog_get_drvdata(wdt);
  75
  76        writel(0, dev->base + WD_COUNTER);
  77
  78        return 0;
  79}
  80
  81static unsigned int tangox_wdt_get_timeleft(struct watchdog_device *wdt)
  82{
  83        struct tangox_wdt_device *dev = watchdog_get_drvdata(wdt);
  84        u32 count;
  85
  86        count = readl(dev->base + WD_COUNTER);
  87
  88        if (!count)
  89                return 0;
  90
  91        return (count - 1) / dev->clk_rate;
  92}
  93
  94static const struct watchdog_info tangox_wdt_info = {
  95        .options  = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
  96        .identity = "tangox watchdog",
  97};
  98
  99static const struct watchdog_ops tangox_wdt_ops = {
 100        .start          = tangox_wdt_start,
 101        .stop           = tangox_wdt_stop,
 102        .set_timeout    = tangox_wdt_set_timeout,
 103        .get_timeleft   = tangox_wdt_get_timeleft,
 104};
 105
 106static int tangox_wdt_restart(struct notifier_block *nb, unsigned long action,
 107                              void *data)
 108{
 109        struct tangox_wdt_device *dev =
 110                container_of(nb, struct tangox_wdt_device, restart);
 111
 112        writel(1, dev->base + WD_COUNTER);
 113
 114        return NOTIFY_DONE;
 115}
 116
 117static int tangox_wdt_probe(struct platform_device *pdev)
 118{
 119        struct tangox_wdt_device *dev;
 120        struct resource *res;
 121        u32 config;
 122        int err;
 123
 124        dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL);
 125        if (!dev)
 126                return -ENOMEM;
 127
 128        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 129        dev->base = devm_ioremap_resource(&pdev->dev, res);
 130        if (IS_ERR(dev->base))
 131                return PTR_ERR(dev->base);
 132
 133        dev->clk = devm_clk_get(&pdev->dev, NULL);
 134        if (IS_ERR(dev->clk))
 135                return PTR_ERR(dev->clk);
 136
 137        err = clk_prepare_enable(dev->clk);
 138        if (err)
 139                return err;
 140
 141        dev->clk_rate = clk_get_rate(dev->clk);
 142        if (!dev->clk_rate) {
 143                err = -EINVAL;
 144                goto err;
 145        }
 146
 147        dev->wdt.parent = &pdev->dev;
 148        dev->wdt.info = &tangox_wdt_info;
 149        dev->wdt.ops = &tangox_wdt_ops;
 150        dev->wdt.timeout = DEFAULT_TIMEOUT;
 151        dev->wdt.min_timeout = 1;
 152        dev->wdt.max_hw_heartbeat_ms = (U32_MAX - 1) / dev->clk_rate;
 153
 154        watchdog_init_timeout(&dev->wdt, timeout, &pdev->dev);
 155        watchdog_set_nowayout(&dev->wdt, nowayout);
 156        watchdog_set_drvdata(&dev->wdt, dev);
 157
 158        /*
 159         * Deactivate counter if disable bit is set to avoid
 160         * accidental reset.
 161         */
 162        config = readl(dev->base + WD_CONFIG);
 163        if (config & WD_CONFIG_DISABLE)
 164                writel(0, dev->base + WD_COUNTER);
 165
 166        writel(WD_CONFIG_XTAL_IN, dev->base + WD_CONFIG);
 167
 168        /*
 169         * Mark as active and restart with configured timeout if
 170         * already running.
 171         */
 172        if (readl(dev->base + WD_COUNTER)) {
 173                set_bit(WDOG_HW_RUNNING, &dev->wdt.status);
 174                tangox_wdt_start(&dev->wdt);
 175        }
 176
 177        err = watchdog_register_device(&dev->wdt);
 178        if (err)
 179                goto err;
 180
 181        platform_set_drvdata(pdev, dev);
 182
 183        dev->restart.notifier_call = tangox_wdt_restart;
 184        dev->restart.priority = 128;
 185        err = register_restart_handler(&dev->restart);
 186        if (err)
 187                dev_warn(&pdev->dev, "failed to register restart handler\n");
 188
 189        dev_info(&pdev->dev, "SMP86xx/SMP87xx watchdog registered\n");
 190
 191        return 0;
 192
 193 err:
 194        clk_disable_unprepare(dev->clk);
 195        return err;
 196}
 197
 198static int tangox_wdt_remove(struct platform_device *pdev)
 199{
 200        struct tangox_wdt_device *dev = platform_get_drvdata(pdev);
 201
 202        tangox_wdt_stop(&dev->wdt);
 203        clk_disable_unprepare(dev->clk);
 204
 205        unregister_restart_handler(&dev->restart);
 206        watchdog_unregister_device(&dev->wdt);
 207
 208        return 0;
 209}
 210
 211static const struct of_device_id tangox_wdt_dt_ids[] = {
 212        { .compatible = "sigma,smp8642-wdt" },
 213        { .compatible = "sigma,smp8759-wdt" },
 214        { }
 215};
 216MODULE_DEVICE_TABLE(of, tangox_wdt_dt_ids);
 217
 218static struct platform_driver tangox_wdt_driver = {
 219        .probe  = tangox_wdt_probe,
 220        .remove = tangox_wdt_remove,
 221        .driver = {
 222                .name           = "tangox-wdt",
 223                .of_match_table = tangox_wdt_dt_ids,
 224        },
 225};
 226
 227module_platform_driver(tangox_wdt_driver);
 228
 229MODULE_AUTHOR("Mans Rullgard <mans@mansr.com>");
 230MODULE_DESCRIPTION("SMP86xx/SMP87xx Watchdog driver");
 231MODULE_LICENSE("GPL");
 232