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