linux/drivers/watchdog/digicolor_wdt.c
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   1// SPDX-License-Identifier: GPL-2.0+
   2/*
   3 * Watchdog driver for Conexant Digicolor
   4 *
   5 * Copyright (C) 2015 Paradox Innovation Ltd.
   6 *
   7 */
   8
   9#include <linux/types.h>
  10#include <linux/module.h>
  11#include <linux/io.h>
  12#include <linux/delay.h>
  13#include <linux/clk.h>
  14#include <linux/watchdog.h>
  15#include <linux/platform_device.h>
  16#include <linux/of_address.h>
  17
  18#define TIMER_A_CONTROL         0
  19#define TIMER_A_COUNT           4
  20
  21#define TIMER_A_ENABLE_COUNT    BIT(0)
  22#define TIMER_A_ENABLE_WATCHDOG BIT(1)
  23
  24struct dc_wdt {
  25        void __iomem            *base;
  26        struct clk              *clk;
  27        spinlock_t              lock;
  28};
  29
  30static unsigned timeout;
  31module_param(timeout, uint, 0);
  32MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds");
  33
  34static void dc_wdt_set(struct dc_wdt *wdt, u32 ticks)
  35{
  36        unsigned long flags;
  37
  38        spin_lock_irqsave(&wdt->lock, flags);
  39
  40        writel_relaxed(0, wdt->base + TIMER_A_CONTROL);
  41        writel_relaxed(ticks, wdt->base + TIMER_A_COUNT);
  42        writel_relaxed(TIMER_A_ENABLE_COUNT | TIMER_A_ENABLE_WATCHDOG,
  43                       wdt->base + TIMER_A_CONTROL);
  44
  45        spin_unlock_irqrestore(&wdt->lock, flags);
  46}
  47
  48static int dc_wdt_restart(struct watchdog_device *wdog, unsigned long action,
  49                          void *data)
  50{
  51        struct dc_wdt *wdt = watchdog_get_drvdata(wdog);
  52
  53        dc_wdt_set(wdt, 1);
  54        /* wait for reset to assert... */
  55        mdelay(500);
  56
  57        return 0;
  58}
  59
  60static int dc_wdt_start(struct watchdog_device *wdog)
  61{
  62        struct dc_wdt *wdt = watchdog_get_drvdata(wdog);
  63
  64        dc_wdt_set(wdt, wdog->timeout * clk_get_rate(wdt->clk));
  65
  66        return 0;
  67}
  68
  69static int dc_wdt_stop(struct watchdog_device *wdog)
  70{
  71        struct dc_wdt *wdt = watchdog_get_drvdata(wdog);
  72
  73        writel_relaxed(0, wdt->base + TIMER_A_CONTROL);
  74
  75        return 0;
  76}
  77
  78static int dc_wdt_set_timeout(struct watchdog_device *wdog, unsigned int t)
  79{
  80        struct dc_wdt *wdt = watchdog_get_drvdata(wdog);
  81
  82        dc_wdt_set(wdt, t * clk_get_rate(wdt->clk));
  83        wdog->timeout = t;
  84
  85        return 0;
  86}
  87
  88static unsigned int dc_wdt_get_timeleft(struct watchdog_device *wdog)
  89{
  90        struct dc_wdt *wdt = watchdog_get_drvdata(wdog);
  91        uint32_t count = readl_relaxed(wdt->base + TIMER_A_COUNT);
  92
  93        return count / clk_get_rate(wdt->clk);
  94}
  95
  96static const struct watchdog_ops dc_wdt_ops = {
  97        .owner          = THIS_MODULE,
  98        .start          = dc_wdt_start,
  99        .stop           = dc_wdt_stop,
 100        .set_timeout    = dc_wdt_set_timeout,
 101        .get_timeleft   = dc_wdt_get_timeleft,
 102        .restart        = dc_wdt_restart,
 103};
 104
 105static const struct watchdog_info dc_wdt_info = {
 106        .options        = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE
 107                        | WDIOF_KEEPALIVEPING,
 108        .identity       = "Conexant Digicolor Watchdog",
 109};
 110
 111static struct watchdog_device dc_wdt_wdd = {
 112        .info           = &dc_wdt_info,
 113        .ops            = &dc_wdt_ops,
 114        .min_timeout    = 1,
 115};
 116
 117static int dc_wdt_probe(struct platform_device *pdev)
 118{
 119        struct resource *res;
 120        struct device *dev = &pdev->dev;
 121        struct dc_wdt *wdt;
 122        int ret;
 123
 124        wdt = devm_kzalloc(dev, sizeof(struct dc_wdt), GFP_KERNEL);
 125        if (!wdt)
 126                return -ENOMEM;
 127
 128        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 129        wdt->base = devm_ioremap_resource(dev, res);
 130        if (IS_ERR(wdt->base))
 131                return PTR_ERR(wdt->base);
 132
 133        wdt->clk = devm_clk_get(dev, NULL);
 134        if (IS_ERR(wdt->clk))
 135                return PTR_ERR(wdt->clk);
 136        dc_wdt_wdd.max_timeout = U32_MAX / clk_get_rate(wdt->clk);
 137        dc_wdt_wdd.timeout = dc_wdt_wdd.max_timeout;
 138        dc_wdt_wdd.parent = dev;
 139
 140        spin_lock_init(&wdt->lock);
 141
 142        watchdog_set_drvdata(&dc_wdt_wdd, wdt);
 143        watchdog_set_restart_priority(&dc_wdt_wdd, 128);
 144        watchdog_init_timeout(&dc_wdt_wdd, timeout, dev);
 145        watchdog_stop_on_reboot(&dc_wdt_wdd);
 146        ret = devm_watchdog_register_device(dev, &dc_wdt_wdd);
 147        if (ret) {
 148                dev_err(dev, "Failed to register watchdog device");
 149                return ret;
 150        }
 151
 152        return 0;
 153}
 154
 155static const struct of_device_id dc_wdt_of_match[] = {
 156        { .compatible = "cnxt,cx92755-wdt", },
 157        {},
 158};
 159MODULE_DEVICE_TABLE(of, dc_wdt_of_match);
 160
 161static struct platform_driver dc_wdt_driver = {
 162        .probe          = dc_wdt_probe,
 163        .driver = {
 164                .name =         "digicolor-wdt",
 165                .of_match_table = dc_wdt_of_match,
 166        },
 167};
 168module_platform_driver(dc_wdt_driver);
 169
 170MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>");
 171MODULE_DESCRIPTION("Driver for Conexant Digicolor watchdog timer");
 172MODULE_LICENSE("GPL");
 173