drivers/watchdog/tangox_wdt.c

   1 /*
   2  *  Copyright (C) 2015 Mans Rullgard <mans@mansr.com>
   3  *  SMP86xx/SMP87xx Watchdog driver
   4  *
   5  *  This program is free software; you can redistribute it and/or modify it
   6  *  under  the terms of the GNU General  Public License as published by the
   7  *  Free Software Foundation;  either version 2 of the License, or (at your
   8  *  option) any later version.
   9  */
  10
  11 #include <linux/bitops.h>
  12 #include <linux/clk.h>
  13 #include <linux/delay.h>
  14 #include <linux/io.h>
  15 #include <linux/kernel.h>
  16 #include <linux/module.h>
  17 #include <linux/moduleparam.h>
  18 #include <linux/notifier.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/reboot.h>
  21 #include <linux/watchdog.h>
  22
  23 #define DEFAULT_TIMEOUT 30
  24
  25 static bool nowayout = WATCHDOG_NOWAYOUT;
  26 module_param(nowayout, bool, 0);
  27 MODULE_PARM_DESC(nowayout,
  28                  "Watchdog cannot be stopped once started (default="
  29                  __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  30
  31 static unsigned int timeout;
  32 module_param(timeout, int, 0);
  33 MODULE_PARM_DESC(timeout, "Watchdog timeout");
  34
  35 /*
  36  * Counter counts down from programmed value.  Reset asserts when
  37  * the counter reaches 1.
  38  */
  39 #define WD_COUNTER              0
  40
  41 #define WD_CONFIG               4
  42 #define WD_CONFIG_XTAL_IN       BIT(0)
  43 #define WD_CONFIG_DISABLE       BIT(31)
  44
  45 struct tangox_wdt_device {
  46         struct watchdog_device wdt;
  47         void __iomem *base;
  48         unsigned long clk_rate;
  49         struct clk *clk;
  50         struct notifier_block restart;
  51 };
  52
  53 static int tangox_wdt_set_timeout(struct watchdog_device *wdt,
  54                                   unsigned int new_timeout)
  55 {
  56         wdt->timeout = new_timeout;
  57
  58         return 0;
  59 }
  60
  61 static int tangox_wdt_start(struct watchdog_device *wdt)
  62 {
  63         struct tangox_wdt_device *dev = watchdog_get_drvdata(wdt);
  64         u32 ticks;
  65
  66         ticks = 1 + wdt->timeout * dev->clk_rate;
  67         writel(ticks, dev->base + WD_COUNTER);
  68
  69         return 0;
  70 }
  71
  72 static int tangox_wdt_stop(struct watchdog_device *wdt)
  73 {
  74         struct tangox_wdt_device *dev = watchdog_get_drvdata(wdt);
  75
  76         writel(0, dev->base + WD_COUNTER);
  77
  78         return 0;
  79 }
  80
  81 static unsigned int tangox_wdt_get_timeleft(struct watchdog_device *wdt)
  82 {
  83         struct tangox_wdt_device *dev = watchdog_get_drvdata(wdt);
  84         u32 count;
  85
  86         count = readl(dev->base + WD_COUNTER);
  87
  88         if (!count)
  89                 return 0;
  90
  91         return (count - 1) / dev->clk_rate;
  92 }
  93
  94 static const struct watchdog_info tangox_wdt_info = {
  95         .options  = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
  96         .identity = "tangox watchdog",
  97 };
  98
  99 static const struct watchdog_ops tangox_wdt_ops = {
 100         .start          = tangox_wdt_start,
 101         .stop           = tangox_wdt_stop,
 102         .set_timeout    = tangox_wdt_set_timeout,
 103         .get_timeleft   = tangox_wdt_get_timeleft,
 104 };
 105
 106 static int tangox_wdt_restart(struct notifier_block *nb, unsigned long action,
 107                               void *data)
 108 {
 109         struct tangox_wdt_device *dev =
 110                 container_of(nb, struct tangox_wdt_device, restart);
 111
 112         writel(1, dev->base + WD_COUNTER);
 113
 114         return NOTIFY_DONE;
 115 }
 116
 117 static int tangox_wdt_probe(struct platform_device *pdev)
 118 {
 119         struct tangox_wdt_device *dev;
 120         struct resource *res;
 121         u32 config;
 122         int err;
 123
 124         dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL);
 125         if (!dev)
 126                 return -ENOMEM;
 127
 128         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 129         dev->base = devm_ioremap_resource(&pdev->dev, res);
 130         if (IS_ERR(dev->base))
 131                 return PTR_ERR(dev->base);
 132
 133         dev->clk = devm_clk_get(&pdev->dev, NULL);
 134         if (IS_ERR(dev->clk))
 135                 return PTR_ERR(dev->clk);
 136
 137         err = clk_prepare_enable(dev->clk);
 138         if (err)
 139                 return err;
 140
 141         dev->clk_rate = clk_get_rate(dev->clk);
 142         if (!dev->clk_rate) {
 143                 err = -EINVAL;
 144                 goto err;
 145         }
 146
 147         dev->wdt.parent = &pdev->dev;
 148         dev->wdt.info = &tangox_wdt_info;
 149         dev->wdt.ops = &tangox_wdt_ops;
 150         dev->wdt.timeout = DEFAULT_TIMEOUT;
 151         dev->wdt.min_timeout = 1;
 152         dev->wdt.max_timeout = (U32_MAX - 1) / dev->clk_rate;
 153
 154         watchdog_init_timeout(&dev->wdt, timeout, &pdev->dev);
 155         watchdog_set_nowayout(&dev->wdt, nowayout);
 156         watchdog_set_drvdata(&dev->wdt, dev);
 157
 158         /*
 159          * Deactivate counter if disable bit is set to avoid
 160          * accidental reset.
 161          */
 162         config = readl(dev->base + WD_CONFIG);
 163         if (config & WD_CONFIG_DISABLE)
 164                 writel(0, dev->base + WD_COUNTER);
 165
 166         writel(WD_CONFIG_XTAL_IN, dev->base + WD_CONFIG);
 167
 168         /*
 169          * Mark as active and restart with configured timeout if
 170          * already running.
 171          */
 172         if (readl(dev->base + WD_COUNTER)) {
 173                 set_bit(WDOG_ACTIVE, &dev->wdt.status);
 174                 tangox_wdt_start(&dev->wdt);
 175         }
 176
 177         err = watchdog_register_device(&dev->wdt);
 178         if (err)
 179                 goto err;
 180
 181         platform_set_drvdata(pdev, dev);
 182
 183         dev->restart.notifier_call = tangox_wdt_restart;
 184         dev->restart.priority = 128;
 185         err = register_restart_handler(&dev->restart);
 186         if (err)
 187                 dev_warn(&pdev->dev, "failed to register restart handler\n");
 188
 189         dev_info(&pdev->dev, "SMP86xx/SMP87xx watchdog registered\n");
 190
 191         return 0;
 192
 193  err:
 194         clk_disable_unprepare(dev->clk);
 195         return err;
 196 }
 197
 198 static int tangox_wdt_remove(struct platform_device *pdev)
 199 {
 200         struct tangox_wdt_device *dev = platform_get_drvdata(pdev);
 201
 202         tangox_wdt_stop(&dev->wdt);
 203         clk_disable_unprepare(dev->clk);
 204
 205         unregister_restart_handler(&dev->restart);
 206         watchdog_unregister_device(&dev->wdt);
 207
 208         return 0;
 209 }
 210
 211 static const struct of_device_id tangox_wdt_dt_ids[] = {
 212         { .compatible = "sigma,smp8642-wdt" },
 213         { .compatible = "sigma,smp8759-wdt" },
 214         { }
 215 };
 216 MODULE_DEVICE_TABLE(of, tangox_wdt_dt_ids);
 217
 218 static struct platform_driver tangox_wdt_driver = {
 219         .probe  = tangox_wdt_probe,
 220         .remove = tangox_wdt_remove,
 221         .driver = {
 222                 .name           = "tangox-wdt",
 223                 .of_match_table = tangox_wdt_dt_ids,
 224         },
 225 };
 226
 227 module_platform_driver(tangox_wdt_driver);
 228
 229 MODULE_AUTHOR("Mans Rullgard <mans@mansr.com>");
 230 MODULE_DESCRIPTION("SMP86xx/SMP87xx Watchdog driver");
 231 MODULE_LICENSE("GPL");