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