drivers/watchdog/digicolor_wdt.c

   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
  24 struct dc_wdt {
  25         void __iomem            *base;
  26         struct clk              *clk;
  27         spinlock_t              lock;
  28 };
  29
  30 static unsigned timeout;
  31 module_param(timeout, uint, 0);
  32 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds");
  33
  34 static 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
  48 static 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
  60 static 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
  69 static 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
  78 static 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
  88 static 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
  96 static 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
 105 static const struct watchdog_info dc_wdt_info = {
 106         .options        = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE
 107                         | WDIOF_KEEPALIVEPING,
 108         .identity       = "Conexant Digicolor Watchdog",
 109 };
 110
 111 static struct watchdog_device dc_wdt_wdd = {
 112         .info           = &dc_wdt_info,
 113         .ops            = &dc_wdt_ops,
 114         .min_timeout    = 1,
 115 };
 116
 117 static int dc_wdt_probe(struct platform_device *pdev)
 118 {
 119         struct device *dev = &pdev->dev;
 120         struct dc_wdt *wdt;
 121
 122         wdt = devm_kzalloc(dev, sizeof(struct dc_wdt), GFP_KERNEL);
 123         if (!wdt)
 124                 return -ENOMEM;
 125
 126         wdt->base = devm_platform_ioremap_resource(pdev, 0);
 127         if (IS_ERR(wdt->base))
 128                 return PTR_ERR(wdt->base);
 129
 130         wdt->clk = devm_clk_get(dev, NULL);
 131         if (IS_ERR(wdt->clk))
 132                 return PTR_ERR(wdt->clk);
 133         dc_wdt_wdd.max_timeout = U32_MAX / clk_get_rate(wdt->clk);
 134         dc_wdt_wdd.timeout = dc_wdt_wdd.max_timeout;
 135         dc_wdt_wdd.parent = dev;
 136
 137         spin_lock_init(&wdt->lock);
 138
 139         watchdog_set_drvdata(&dc_wdt_wdd, wdt);
 140         watchdog_set_restart_priority(&dc_wdt_wdd, 128);
 141         watchdog_init_timeout(&dc_wdt_wdd, timeout, dev);
 142         watchdog_stop_on_reboot(&dc_wdt_wdd);
 143         return devm_watchdog_register_device(dev, &dc_wdt_wdd);
 144 }
 145
 146 static const struct of_device_id dc_wdt_of_match[] = {
 147         { .compatible = "cnxt,cx92755-wdt", },
 148         {},
 149 };
 150 MODULE_DEVICE_TABLE(of, dc_wdt_of_match);
 151
 152 static struct platform_driver dc_wdt_driver = {
 153         .probe          = dc_wdt_probe,
 154         .driver = {
 155                 .name =         "digicolor-wdt",
 156                 .of_match_table = dc_wdt_of_match,
 157         },
 158 };
 159 module_platform_driver(dc_wdt_driver);
 160
 161 MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>");
 162 MODULE_DESCRIPTION("Driver for Conexant Digicolor watchdog timer");
 163 MODULE_LICENSE("GPL");