drivers/watchdog/ts4800_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Watchdog driver for TS-4800 based boards
   4  *
   5  * Copyright (c) 2015 - Savoir-faire Linux
   6  *
   7  */
   8
   9 #include <linux/kernel.h>
  10 #include <linux/mfd/syscon.h>
  11 #include <linux/module.h>
  12 #include <linux/of.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/regmap.h>
  15 #include <linux/watchdog.h>
  16
  17 static bool nowayout = WATCHDOG_NOWAYOUT;
  18 module_param(nowayout, bool, 0);
  19 MODULE_PARM_DESC(nowayout,
  20         "Watchdog cannot be stopped once started (default="
  21         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  22
  23 /* possible feed values */
  24 #define TS4800_WDT_FEED_2S       0x1
  25 #define TS4800_WDT_FEED_10S      0x2
  26 #define TS4800_WDT_DISABLE       0x3
  27
  28 struct ts4800_wdt {
  29         struct watchdog_device  wdd;
  30         struct regmap           *regmap;
  31         u32                     feed_offset;
  32         u32                     feed_val;
  33 };
  34
  35 /*
  36  * TS-4800 supports the following timeout values:
  37  *
  38  *   value desc
  39  *   ---------------------
  40  *     0    feed for 338ms
  41  *     1    feed for 2.706s
  42  *     2    feed for 10.824s
  43  *     3    disable watchdog
  44  *
  45  * Keep the regmap/timeout map ordered by timeout
  46  */
  47 static const struct {
  48         const int timeout;
  49         const int regval;
  50 } ts4800_wdt_map[] = {
  51         { 2,  TS4800_WDT_FEED_2S },
  52         { 10, TS4800_WDT_FEED_10S },
  53 };
  54
  55 #define MAX_TIMEOUT_INDEX       (ARRAY_SIZE(ts4800_wdt_map) - 1)
  56
  57 static void ts4800_write_feed(struct ts4800_wdt *wdt, u32 val)
  58 {
  59         regmap_write(wdt->regmap, wdt->feed_offset, val);
  60 }
  61
  62 static int ts4800_wdt_start(struct watchdog_device *wdd)
  63 {
  64         struct ts4800_wdt *wdt = watchdog_get_drvdata(wdd);
  65
  66         ts4800_write_feed(wdt, wdt->feed_val);
  67         return 0;
  68 }
  69
  70 static int ts4800_wdt_stop(struct watchdog_device *wdd)
  71 {
  72         struct ts4800_wdt *wdt = watchdog_get_drvdata(wdd);
  73
  74         ts4800_write_feed(wdt, TS4800_WDT_DISABLE);
  75         return 0;
  76 }
  77
  78 static int ts4800_wdt_set_timeout(struct watchdog_device *wdd,
  79                                   unsigned int timeout)
  80 {
  81         struct ts4800_wdt *wdt = watchdog_get_drvdata(wdd);
  82         int i;
  83
  84         for (i = 0; i < MAX_TIMEOUT_INDEX; i++) {
  85                 if (ts4800_wdt_map[i].timeout >= timeout)
  86                         break;
  87         }
  88
  89         wdd->timeout = ts4800_wdt_map[i].timeout;
  90         wdt->feed_val = ts4800_wdt_map[i].regval;
  91
  92         return 0;
  93 }
  94
  95 static const struct watchdog_ops ts4800_wdt_ops = {
  96         .owner = THIS_MODULE,
  97         .start = ts4800_wdt_start,
  98         .stop = ts4800_wdt_stop,
  99         .set_timeout = ts4800_wdt_set_timeout,
 100 };
 101
 102 static const struct watchdog_info ts4800_wdt_info = {
 103         .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
 104         .identity = "TS-4800 Watchdog",
 105 };
 106
 107 static int ts4800_wdt_probe(struct platform_device *pdev)
 108 {
 109         struct device *dev = &pdev->dev;
 110         struct device_node *np = dev->of_node;
 111         struct device_node *syscon_np;
 112         struct watchdog_device *wdd;
 113         struct ts4800_wdt *wdt;
 114         u32 reg;
 115         int ret;
 116
 117         syscon_np = of_parse_phandle(np, "syscon", 0);
 118         if (!syscon_np) {
 119                 dev_err(dev, "no syscon property\n");
 120                 return -ENODEV;
 121         }
 122
 123         ret = of_property_read_u32_index(np, "syscon", 1, &reg);
 124         if (ret < 0) {
 125                 dev_err(dev, "no offset in syscon\n");
 126                 of_node_put(syscon_np);
 127                 return ret;
 128         }
 129
 130         /* allocate memory for watchdog struct */
 131         wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
 132         if (!wdt) {
 133                 of_node_put(syscon_np);
 134                 return -ENOMEM;
 135         }
 136
 137         /* set regmap and offset to know where to write */
 138         wdt->feed_offset = reg;
 139         wdt->regmap = syscon_node_to_regmap(syscon_np);
 140         of_node_put(syscon_np);
 141         if (IS_ERR(wdt->regmap)) {
 142                 dev_err(dev, "cannot get parent's regmap\n");
 143                 return PTR_ERR(wdt->regmap);
 144         }
 145
 146         /* Initialize struct watchdog_device */
 147         wdd = &wdt->wdd;
 148         wdd->parent = dev;
 149         wdd->info = &ts4800_wdt_info;
 150         wdd->ops = &ts4800_wdt_ops;
 151         wdd->min_timeout = ts4800_wdt_map[0].timeout;
 152         wdd->max_timeout = ts4800_wdt_map[MAX_TIMEOUT_INDEX].timeout;
 153
 154         watchdog_set_drvdata(wdd, wdt);
 155         watchdog_set_nowayout(wdd, nowayout);
 156         watchdog_init_timeout(wdd, 0, dev);
 157
 158         /*
 159          * As this watchdog supports only a few values, ts4800_wdt_set_timeout
 160          * must be called to initialize timeout and feed_val with valid values.
 161          * Default to maximum timeout if none, or an invalid one, is provided in
 162          * device tree.
 163          */
 164         if (!wdd->timeout)
 165                 wdd->timeout = wdd->max_timeout;
 166         ts4800_wdt_set_timeout(wdd, wdd->timeout);
 167
 168         /*
 169          * The feed register is write-only, so it is not possible to determine
 170          * watchdog's state. Disable it to be in a known state.
 171          */
 172         ts4800_wdt_stop(wdd);
 173
 174         ret = devm_watchdog_register_device(dev, wdd);
 175         if (ret)
 176                 return ret;
 177
 178         platform_set_drvdata(pdev, wdt);
 179
 180         dev_info(dev, "initialized (timeout = %d sec, nowayout = %d)\n",
 181                  wdd->timeout, nowayout);
 182
 183         return 0;
 184 }
 185
 186 static const struct of_device_id ts4800_wdt_of_match[] = {
 187         { .compatible = "technologic,ts4800-wdt", },
 188         { },
 189 };
 190 MODULE_DEVICE_TABLE(of, ts4800_wdt_of_match);
 191
 192 static struct platform_driver ts4800_wdt_driver = {
 193         .probe          = ts4800_wdt_probe,
 194         .driver         = {
 195                 .name   = "ts4800_wdt",
 196                 .of_match_table = ts4800_wdt_of_match,
 197         },
 198 };
 199
 200 module_platform_driver(ts4800_wdt_driver);
 201
 202 MODULE_AUTHOR("Damien Riegel <damien.riegel@savoirfairelinux.com>");
 203 MODULE_DESCRIPTION("Watchdog driver for TS-4800 based boards");
 204 MODULE_LICENSE("GPL v2");
 205 MODULE_ALIAS("platform:ts4800_wdt");