drivers/watchdog/tangox_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  *  Copyright (C) 2015 Mans Rullgard <mans@mansr.com>
   4  *  SMP86xx/SMP87xx Watchdog driver
   5  */
   6
   7 #include <linux/bitops.h>
   8 #include <linux/clk.h>
   9 #include <linux/delay.h>
  10 #include <linux/io.h>
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <linux/moduleparam.h>
  14 #include <linux/mod_devicetable.h>
  15 #include <linux/platform_device.h>
  16 #include <linux/watchdog.h>
  17
  18 #define DEFAULT_TIMEOUT 30
  19
  20 static bool nowayout = WATCHDOG_NOWAYOUT;
  21 module_param(nowayout, bool, 0);
  22 MODULE_PARM_DESC(nowayout,
  23                  "Watchdog cannot be stopped once started (default="
  24                  __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  25
  26 static unsigned int timeout;
  27 module_param(timeout, int, 0);
  28 MODULE_PARM_DESC(timeout, "Watchdog timeout");
  29
  30 /*
  31  * Counter counts down from programmed value.  Reset asserts when
  32  * the counter reaches 1.
  33  */
  34 #define WD_COUNTER              0
  35
  36 #define WD_CONFIG               4
  37 #define WD_CONFIG_XTAL_IN       BIT(0)
  38 #define WD_CONFIG_DISABLE       BIT(31)
  39
  40 struct tangox_wdt_device {
  41         struct watchdog_device wdt;
  42         void __iomem *base;
  43         unsigned long clk_rate;
  44         struct clk *clk;
  45 };
  46
  47 static int tangox_wdt_set_timeout(struct watchdog_device *wdt,
  48                                   unsigned int new_timeout)
  49 {
  50         wdt->timeout = new_timeout;
  51
  52         return 0;
  53 }
  54
  55 static int tangox_wdt_start(struct watchdog_device *wdt)
  56 {
  57         struct tangox_wdt_device *dev = watchdog_get_drvdata(wdt);
  58         u32 ticks;
  59
  60         ticks = 1 + wdt->timeout * dev->clk_rate;
  61         writel(ticks, dev->base + WD_COUNTER);
  62
  63         return 0;
  64 }
  65
  66 static int tangox_wdt_stop(struct watchdog_device *wdt)
  67 {
  68         struct tangox_wdt_device *dev = watchdog_get_drvdata(wdt);
  69
  70         writel(0, dev->base + WD_COUNTER);
  71
  72         return 0;
  73 }
  74
  75 static unsigned int tangox_wdt_get_timeleft(struct watchdog_device *wdt)
  76 {
  77         struct tangox_wdt_device *dev = watchdog_get_drvdata(wdt);
  78         u32 count;
  79
  80         count = readl(dev->base + WD_COUNTER);
  81
  82         if (!count)
  83                 return 0;
  84
  85         return (count - 1) / dev->clk_rate;
  86 }
  87
  88 static const struct watchdog_info tangox_wdt_info = {
  89         .options  = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
  90         .identity = "tangox watchdog",
  91 };
  92
  93 static int tangox_wdt_restart(struct watchdog_device *wdt,
  94                               unsigned long action, void *data)
  95 {
  96         struct tangox_wdt_device *dev = watchdog_get_drvdata(wdt);
  97
  98         writel(1, dev->base + WD_COUNTER);
  99
 100         return 0;
 101 }
 102
 103 static const struct watchdog_ops tangox_wdt_ops = {
 104         .start          = tangox_wdt_start,
 105         .stop           = tangox_wdt_stop,
 106         .set_timeout    = tangox_wdt_set_timeout,
 107         .get_timeleft   = tangox_wdt_get_timeleft,
 108         .restart        = tangox_wdt_restart,
 109 };
 110
 111 static void tangox_clk_disable_unprepare(void *data)
 112 {
 113         clk_disable_unprepare(data);
 114 }
 115
 116 static int tangox_wdt_probe(struct platform_device *pdev)
 117 {
 118         struct tangox_wdt_device *dev;
 119         u32 config;
 120         int err;
 121
 122         dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL);
 123         if (!dev)
 124                 return -ENOMEM;
 125
 126         dev->base = devm_platform_ioremap_resource(pdev, 0);
 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         err = devm_add_action_or_reset(&pdev->dev,
 138                                        tangox_clk_disable_unprepare, dev->clk);
 139         if (err)
 140                 return err;
 141
 142         dev->clk_rate = clk_get_rate(dev->clk);
 143         if (!dev->clk_rate)
 144                 return -EINVAL;
 145
 146         dev->wdt.parent = &pdev->dev;
 147         dev->wdt.info = &tangox_wdt_info;
 148         dev->wdt.ops = &tangox_wdt_ops;
 149         dev->wdt.timeout = DEFAULT_TIMEOUT;
 150         dev->wdt.min_timeout = 1;
 151         dev->wdt.max_hw_heartbeat_ms = (U32_MAX - 1) / dev->clk_rate;
 152
 153         watchdog_init_timeout(&dev->wdt, timeout, &pdev->dev);
 154         watchdog_set_nowayout(&dev->wdt, nowayout);
 155         watchdog_set_drvdata(&dev->wdt, dev);
 156
 157         /*
 158          * Deactivate counter if disable bit is set to avoid
 159          * accidental reset.
 160          */
 161         config = readl(dev->base + WD_CONFIG);
 162         if (config & WD_CONFIG_DISABLE)
 163                 writel(0, dev->base + WD_COUNTER);
 164
 165         writel(WD_CONFIG_XTAL_IN, dev->base + WD_CONFIG);
 166
 167         /*
 168          * Mark as active and restart with configured timeout if
 169          * already running.
 170          */
 171         if (readl(dev->base + WD_COUNTER)) {
 172                 set_bit(WDOG_HW_RUNNING, &dev->wdt.status);
 173                 tangox_wdt_start(&dev->wdt);
 174         }
 175
 176         watchdog_set_restart_priority(&dev->wdt, 128);
 177
 178         watchdog_stop_on_unregister(&dev->wdt);
 179         err = devm_watchdog_register_device(&pdev->dev, &dev->wdt);
 180         if (err)
 181                 return err;
 182
 183         platform_set_drvdata(pdev, dev);
 184
 185         dev_info(&pdev->dev, "SMP86xx/SMP87xx watchdog registered\n");
 186
 187         return 0;
 188 }
 189
 190 static const struct of_device_id tangox_wdt_dt_ids[] = {
 191         { .compatible = "sigma,smp8642-wdt" },
 192         { .compatible = "sigma,smp8759-wdt" },
 193         { }
 194 };
 195 MODULE_DEVICE_TABLE(of, tangox_wdt_dt_ids);
 196
 197 static struct platform_driver tangox_wdt_driver = {
 198         .probe  = tangox_wdt_probe,
 199         .driver = {
 200                 .name           = "tangox-wdt",
 201                 .of_match_table = tangox_wdt_dt_ids,
 202         },
 203 };
 204
 205 module_platform_driver(tangox_wdt_driver);
 206
 207 MODULE_AUTHOR("Mans Rullgard <mans@mansr.com>");
 208 MODULE_DESCRIPTION("SMP86xx/SMP87xx Watchdog driver");
 209 MODULE_LICENSE("GPL");