drivers/watchdog/digicolor_wdt.c

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