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 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 device *dev = &pdev->dev;
 123         struct device_node *np = dev->of_node;
 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         platform_set_drvdata(pdev, wdt);
 131
 132         wdt->base = of_iomap(np, 0);
 133         if (!wdt->base) {
 134                 dev_err(dev, "Failed to remap watchdog regs");
 135                 return -ENODEV;
 136         }
 137
 138         wdt->clk = devm_clk_get(&pdev->dev, NULL);
 139         if (IS_ERR(wdt->clk)) {
 140                 ret = PTR_ERR(wdt->clk);
 141                 goto err_iounmap;
 142         }
 143         dc_wdt_wdd.max_timeout = U32_MAX / clk_get_rate(wdt->clk);
 144         dc_wdt_wdd.timeout = dc_wdt_wdd.max_timeout;
 145         dc_wdt_wdd.parent = &pdev->dev;
 146
 147         spin_lock_init(&wdt->lock);
 148
 149         watchdog_set_drvdata(&dc_wdt_wdd, wdt);
 150         watchdog_set_restart_priority(&dc_wdt_wdd, 128);
 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         return 0;
 159
 160 err_iounmap:
 161         iounmap(wdt->base);
 162         return ret;
 163 }
 164
 165 static int dc_wdt_remove(struct platform_device *pdev)
 166 {
 167         struct dc_wdt *wdt = platform_get_drvdata(pdev);
 168
 169         watchdog_unregister_device(&dc_wdt_wdd);
 170         iounmap(wdt->base);
 171
 172         return 0;
 173 }
 174
 175 static void dc_wdt_shutdown(struct platform_device *pdev)
 176 {
 177         dc_wdt_stop(&dc_wdt_wdd);
 178 }
 179
 180 static const struct of_device_id dc_wdt_of_match[] = {
 181         { .compatible = "cnxt,cx92755-wdt", },
 182         {},
 183 };
 184 MODULE_DEVICE_TABLE(of, dc_wdt_of_match);
 185
 186 static struct platform_driver dc_wdt_driver = {
 187         .probe          = dc_wdt_probe,
 188         .remove         = dc_wdt_remove,
 189         .shutdown       = dc_wdt_shutdown,
 190         .driver = {
 191                 .name =         "digicolor-wdt",
 192                 .of_match_table = dc_wdt_of_match,
 193         },
 194 };
 195 module_platform_driver(dc_wdt_driver);
 196
 197 MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>");
 198 MODULE_DESCRIPTION("Driver for Conexant Digicolor watchdog timer");
 199 MODULE_LICENSE("GPL");