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)
  52 {
  53         struct dc_wdt *wdt = watchdog_get_drvdata(wdog);
  54
  55         dc_wdt_set(wdt, 1);
  56         /* wait for reset to assert... */
  57         mdelay(500);
  58
  59         return 0;
  60 }
  61
  62 static int dc_wdt_start(struct watchdog_device *wdog)
  63 {
  64         struct dc_wdt *wdt = watchdog_get_drvdata(wdog);
  65
  66         dc_wdt_set(wdt, wdog->timeout * clk_get_rate(wdt->clk));
  67
  68         return 0;
  69 }
  70
  71 static int dc_wdt_stop(struct watchdog_device *wdog)
  72 {
  73         struct dc_wdt *wdt = watchdog_get_drvdata(wdog);
  74
  75         writel_relaxed(0, wdt->base + TIMER_A_CONTROL);
  76
  77         return 0;
  78 }
  79
  80 static int dc_wdt_set_timeout(struct watchdog_device *wdog, unsigned int t)
  81 {
  82         struct dc_wdt *wdt = watchdog_get_drvdata(wdog);
  83
  84         dc_wdt_set(wdt, t * clk_get_rate(wdt->clk));
  85         wdog->timeout = t;
  86
  87         return 0;
  88 }
  89
  90 static unsigned int dc_wdt_get_timeleft(struct watchdog_device *wdog)
  91 {
  92         struct dc_wdt *wdt = watchdog_get_drvdata(wdog);
  93         uint32_t count = readl_relaxed(wdt->base + TIMER_A_COUNT);
  94
  95         return count / clk_get_rate(wdt->clk);
  96 }
  97
  98 static struct watchdog_ops dc_wdt_ops = {
  99         .owner          = THIS_MODULE,
 100         .start          = dc_wdt_start,
 101         .stop           = dc_wdt_stop,
 102         .set_timeout    = dc_wdt_set_timeout,
 103         .get_timeleft   = dc_wdt_get_timeleft,
 104         .restart        = dc_wdt_restart,
 105 };
 106
 107 static struct watchdog_info dc_wdt_info = {
 108         .options        = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE
 109                         | WDIOF_KEEPALIVEPING,
 110         .identity       = "Conexant Digicolor Watchdog",
 111 };
 112
 113 static struct watchdog_device dc_wdt_wdd = {
 114         .info           = &dc_wdt_info,
 115         .ops            = &dc_wdt_ops,
 116         .min_timeout    = 1,
 117 };
 118
 119 static int dc_wdt_probe(struct platform_device *pdev)
 120 {
 121         struct device *dev = &pdev->dev;
 122         struct device_node *np = dev->of_node;
 123         struct dc_wdt *wdt;
 124         int ret;
 125
 126         wdt = devm_kzalloc(dev, sizeof(struct dc_wdt), GFP_KERNEL);
 127         if (!wdt)
 128                 return -ENOMEM;
 129         platform_set_drvdata(pdev, wdt);
 130
 131         wdt->base = of_iomap(np, 0);
 132         if (!wdt->base) {
 133                 dev_err(dev, "Failed to remap watchdog regs");
 134                 return -ENODEV;
 135         }
 136
 137         wdt->clk = devm_clk_get(&pdev->dev, NULL);
 138         if (IS_ERR(wdt->clk)) {
 139                 ret = PTR_ERR(wdt->clk);
 140                 goto err_iounmap;
 141         }
 142         dc_wdt_wdd.max_timeout = U32_MAX / clk_get_rate(wdt->clk);
 143         dc_wdt_wdd.timeout = dc_wdt_wdd.max_timeout;
 144         dc_wdt_wdd.parent = &pdev->dev;
 145
 146         spin_lock_init(&wdt->lock);
 147
 148         watchdog_set_drvdata(&dc_wdt_wdd, wdt);
 149         watchdog_set_restart_priority(&dc_wdt_wdd, 128);
 150         watchdog_init_timeout(&dc_wdt_wdd, timeout, dev);
 151         ret = watchdog_register_device(&dc_wdt_wdd);
 152         if (ret) {
 153                 dev_err(dev, "Failed to register watchdog device");
 154                 goto err_iounmap;
 155         }
 156
 157         return 0;
 158
 159 err_iounmap:
 160         iounmap(wdt->base);
 161         return ret;
 162 }
 163
 164 static int dc_wdt_remove(struct platform_device *pdev)
 165 {
 166         struct dc_wdt *wdt = platform_get_drvdata(pdev);
 167
 168         watchdog_unregister_device(&dc_wdt_wdd);
 169         iounmap(wdt->base);
 170
 171         return 0;
 172 }
 173
 174 static void dc_wdt_shutdown(struct platform_device *pdev)
 175 {
 176         dc_wdt_stop(&dc_wdt_wdd);
 177 }
 178
 179 static const struct of_device_id dc_wdt_of_match[] = {
 180         { .compatible = "cnxt,cx92755-wdt", },
 181         {},
 182 };
 183 MODULE_DEVICE_TABLE(of, dc_wdt_of_match);
 184
 185 static struct platform_driver dc_wdt_driver = {
 186         .probe          = dc_wdt_probe,
 187         .remove         = dc_wdt_remove,
 188         .shutdown       = dc_wdt_shutdown,
 189         .driver = {
 190                 .name =         "digicolor-wdt",
 191                 .of_match_table = dc_wdt_of_match,
 192         },
 193 };
 194 module_platform_driver(dc_wdt_driver);
 195
 196 MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>");
 197 MODULE_DESCRIPTION("Driver for Conexant Digicolor watchdog timer");
 198 MODULE_LICENSE("GPL");