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/reboot.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/of_address.h>
  21
  22 #define TIMER_A_CONTROL         0
  23 #define TIMER_A_COUNT           4
  24
  25 #define TIMER_A_ENABLE_COUNT    BIT(0)
  26 #define TIMER_A_ENABLE_WATCHDOG BIT(1)
  27
  28 struct dc_wdt {
  29         void __iomem            *base;
  30         struct clk              *clk;
  31         struct notifier_block   restart_handler;
  32         spinlock_t              lock;
  33 };
  34
  35 static unsigned timeout;
  36 module_param(timeout, uint, 0);
  37 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds");
  38
  39 static void dc_wdt_set(struct dc_wdt *wdt, u32 ticks)
  40 {
  41         unsigned long flags;
  42
  43         spin_lock_irqsave(&wdt->lock, flags);
  44
  45         writel_relaxed(0, wdt->base + TIMER_A_CONTROL);
  46         writel_relaxed(ticks, wdt->base + TIMER_A_COUNT);
  47         writel_relaxed(TIMER_A_ENABLE_COUNT | TIMER_A_ENABLE_WATCHDOG,
  48                        wdt->base + TIMER_A_CONTROL);
  49
  50         spin_unlock_irqrestore(&wdt->lock, flags);
  51 }
  52
  53 static int dc_restart_handler(struct notifier_block *this, unsigned long mode,
  54                               void *cmd)
  55 {
  56         struct dc_wdt *wdt = container_of(this, struct dc_wdt, restart_handler);
  57
  58         dc_wdt_set(wdt, 1);
  59         /* wait for reset to assert... */
  60         mdelay(500);
  61
  62         return NOTIFY_DONE;
  63 }
  64
  65 static int dc_wdt_start(struct watchdog_device *wdog)
  66 {
  67         struct dc_wdt *wdt = watchdog_get_drvdata(wdog);
  68
  69         dc_wdt_set(wdt, wdog->timeout * clk_get_rate(wdt->clk));
  70
  71         return 0;
  72 }
  73
  74 static int dc_wdt_stop(struct watchdog_device *wdog)
  75 {
  76         struct dc_wdt *wdt = watchdog_get_drvdata(wdog);
  77
  78         writel_relaxed(0, wdt->base + TIMER_A_CONTROL);
  79
  80         return 0;
  81 }
  82
  83 static int dc_wdt_set_timeout(struct watchdog_device *wdog, unsigned int t)
  84 {
  85         struct dc_wdt *wdt = watchdog_get_drvdata(wdog);
  86
  87         dc_wdt_set(wdt, t * clk_get_rate(wdt->clk));
  88         wdog->timeout = t;
  89
  90         return 0;
  91 }
  92
  93 static unsigned int dc_wdt_get_timeleft(struct watchdog_device *wdog)
  94 {
  95         struct dc_wdt *wdt = watchdog_get_drvdata(wdog);
  96         uint32_t count = readl_relaxed(wdt->base + TIMER_A_COUNT);
  97
  98         return count / clk_get_rate(wdt->clk);
  99 }
 100
 101 static struct watchdog_ops dc_wdt_ops = {
 102         .owner          = THIS_MODULE,
 103         .start          = dc_wdt_start,
 104         .stop           = dc_wdt_stop,
 105         .set_timeout    = dc_wdt_set_timeout,
 106         .get_timeleft   = dc_wdt_get_timeleft,
 107 };
 108
 109 static struct watchdog_info dc_wdt_info = {
 110         .options        = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE
 111                         | WDIOF_KEEPALIVEPING,
 112         .identity       = "Conexant Digicolor Watchdog",
 113 };
 114
 115 static struct watchdog_device dc_wdt_wdd = {
 116         .info           = &dc_wdt_info,
 117         .ops            = &dc_wdt_ops,
 118         .min_timeout    = 1,
 119 };
 120
 121 static int dc_wdt_probe(struct platform_device *pdev)
 122 {
 123         struct device *dev = &pdev->dev;
 124         struct device_node *np = dev->of_node;
 125         struct dc_wdt *wdt;
 126         int ret;
 127
 128         wdt = devm_kzalloc(dev, sizeof(struct dc_wdt), GFP_KERNEL);
 129         if (!wdt)
 130                 return -ENOMEM;
 131         platform_set_drvdata(pdev, wdt);
 132
 133         wdt->base = of_iomap(np, 0);
 134         if (!wdt->base) {
 135                 dev_err(dev, "Failed to remap watchdog regs");
 136                 return -ENODEV;
 137         }
 138
 139         wdt->clk = devm_clk_get(&pdev->dev, NULL);
 140         if (IS_ERR(wdt->clk)) {
 141                 ret = PTR_ERR(wdt->clk);
 142                 goto err_iounmap;
 143         }
 144         dc_wdt_wdd.max_timeout = U32_MAX / clk_get_rate(wdt->clk);
 145         dc_wdt_wdd.timeout = dc_wdt_wdd.max_timeout;
 146         dc_wdt_wdd.parent = &pdev->dev;
 147
 148         spin_lock_init(&wdt->lock);
 149
 150         watchdog_set_drvdata(&dc_wdt_wdd, wdt);
 151         watchdog_init_timeout(&dc_wdt_wdd, timeout, dev);
 152         ret = watchdog_register_device(&dc_wdt_wdd);
 153         if (ret) {
 154                 dev_err(dev, "Failed to register watchdog device");
 155                 goto err_iounmap;
 156         }
 157
 158         wdt->restart_handler.notifier_call = dc_restart_handler;
 159         wdt->restart_handler.priority = 128;
 160         ret = register_restart_handler(&wdt->restart_handler);
 161         if (ret)
 162                 dev_warn(&pdev->dev, "cannot register restart handler\n");
 163
 164         return 0;
 165
 166 err_iounmap:
 167         iounmap(wdt->base);
 168         return ret;
 169 }
 170
 171 static int dc_wdt_remove(struct platform_device *pdev)
 172 {
 173         struct dc_wdt *wdt = platform_get_drvdata(pdev);
 174
 175         unregister_restart_handler(&wdt->restart_handler);
 176         watchdog_unregister_device(&dc_wdt_wdd);
 177         iounmap(wdt->base);
 178
 179         return 0;
 180 }
 181
 182 static void dc_wdt_shutdown(struct platform_device *pdev)
 183 {
 184         dc_wdt_stop(&dc_wdt_wdd);
 185 }
 186
 187 static const struct of_device_id dc_wdt_of_match[] = {
 188         { .compatible = "cnxt,cx92755-wdt", },
 189         {},
 190 };
 191 MODULE_DEVICE_TABLE(of, dc_wdt_of_match);
 192
 193 static struct platform_driver dc_wdt_driver = {
 194         .probe          = dc_wdt_probe,
 195         .remove         = dc_wdt_remove,
 196         .shutdown       = dc_wdt_shutdown,
 197         .driver = {
 198                 .name =         "digicolor-wdt",
 199                 .of_match_table = dc_wdt_of_match,
 200         },
 201 };
 202 module_platform_driver(dc_wdt_driver);
 203
 204 MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>");
 205 MODULE_DESCRIPTION("Driver for Conexant Digicolor watchdog timer");
 206 MODULE_LICENSE("GPL");