drivers/watchdog/jz4740_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  Copyright (C) 2010, Paul Cercueil <paul@crapouillou.net>
   4  *  JZ4740 Watchdog driver
   5  */
   6
   7 #include <linux/mfd/ingenic-tcu.h>
   8 #include <linux/mfd/syscon.h>
   9 #include <linux/module.h>
  10 #include <linux/moduleparam.h>
  11 #include <linux/types.h>
  12 #include <linux/kernel.h>
  13 #include <linux/watchdog.h>
  14 #include <linux/platform_device.h>
  15 #include <linux/io.h>
  16 #include <linux/device.h>
  17 #include <linux/clk.h>
  18 #include <linux/slab.h>
  19 #include <linux/err.h>
  20 #include <linux/of.h>
  21 #include <linux/regmap.h>
  22
  23 #define DEFAULT_HEARTBEAT 5
  24 #define MAX_HEARTBEAT     2048
  25
  26 static bool nowayout = WATCHDOG_NOWAYOUT;
  27 module_param(nowayout, bool, 0);
  28 MODULE_PARM_DESC(nowayout,
  29                  "Watchdog cannot be stopped once started (default="
  30                  __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  31
  32 static unsigned int heartbeat = DEFAULT_HEARTBEAT;
  33 module_param(heartbeat, uint, 0);
  34 MODULE_PARM_DESC(heartbeat,
  35                 "Watchdog heartbeat period in seconds from 1 to "
  36                 __MODULE_STRING(MAX_HEARTBEAT) ", default "
  37                 __MODULE_STRING(DEFAULT_HEARTBEAT));
  38
  39 struct jz4740_wdt_drvdata {
  40         struct watchdog_device wdt;
  41         struct regmap *map;
  42         struct clk *clk;
  43         unsigned long clk_rate;
  44 };
  45
  46 static int jz4740_wdt_ping(struct watchdog_device *wdt_dev)
  47 {
  48         struct jz4740_wdt_drvdata *drvdata = watchdog_get_drvdata(wdt_dev);
  49
  50         regmap_write(drvdata->map, TCU_REG_WDT_TCNT, 0);
  51
  52         return 0;
  53 }
  54
  55 static int jz4740_wdt_set_timeout(struct watchdog_device *wdt_dev,
  56                                     unsigned int new_timeout)
  57 {
  58         struct jz4740_wdt_drvdata *drvdata = watchdog_get_drvdata(wdt_dev);
  59         u16 timeout_value = (u16)(drvdata->clk_rate * new_timeout);
  60         unsigned int tcer;
  61
  62         regmap_read(drvdata->map, TCU_REG_WDT_TCER, &tcer);
  63         regmap_write(drvdata->map, TCU_REG_WDT_TCER, 0);
  64
  65         regmap_write(drvdata->map, TCU_REG_WDT_TDR, timeout_value);
  66         regmap_write(drvdata->map, TCU_REG_WDT_TCNT, 0);
  67
  68         if (tcer & TCU_WDT_TCER_TCEN)
  69                 regmap_write(drvdata->map, TCU_REG_WDT_TCER, TCU_WDT_TCER_TCEN);
  70
  71         wdt_dev->timeout = new_timeout;
  72         return 0;
  73 }
  74
  75 static int jz4740_wdt_start(struct watchdog_device *wdt_dev)
  76 {
  77         struct jz4740_wdt_drvdata *drvdata = watchdog_get_drvdata(wdt_dev);
  78         unsigned int tcer;
  79         int ret;
  80
  81         ret = clk_prepare_enable(drvdata->clk);
  82         if (ret)
  83                 return ret;
  84
  85         regmap_read(drvdata->map, TCU_REG_WDT_TCER, &tcer);
  86
  87         jz4740_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
  88
  89         /* Start watchdog if it wasn't started already */
  90         if (!(tcer & TCU_WDT_TCER_TCEN))
  91                 regmap_write(drvdata->map, TCU_REG_WDT_TCER, TCU_WDT_TCER_TCEN);
  92
  93         return 0;
  94 }
  95
  96 static int jz4740_wdt_stop(struct watchdog_device *wdt_dev)
  97 {
  98         struct jz4740_wdt_drvdata *drvdata = watchdog_get_drvdata(wdt_dev);
  99
 100         regmap_write(drvdata->map, TCU_REG_WDT_TCER, 0);
 101         clk_disable_unprepare(drvdata->clk);
 102
 103         return 0;
 104 }
 105
 106 static int jz4740_wdt_restart(struct watchdog_device *wdt_dev,
 107                               unsigned long action, void *data)
 108 {
 109         wdt_dev->timeout = 0;
 110         jz4740_wdt_start(wdt_dev);
 111         return 0;
 112 }
 113
 114 static const struct watchdog_info jz4740_wdt_info = {
 115         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 116         .identity = "jz4740 Watchdog",
 117 };
 118
 119 static const struct watchdog_ops jz4740_wdt_ops = {
 120         .owner = THIS_MODULE,
 121         .start = jz4740_wdt_start,
 122         .stop = jz4740_wdt_stop,
 123         .ping = jz4740_wdt_ping,
 124         .set_timeout = jz4740_wdt_set_timeout,
 125         .restart = jz4740_wdt_restart,
 126 };
 127
 128 #ifdef CONFIG_OF
 129 static const struct of_device_id jz4740_wdt_of_matches[] = {
 130         { .compatible = "ingenic,jz4740-watchdog", },
 131         { .compatible = "ingenic,jz4780-watchdog", },
 132         { /* sentinel */ }
 133 };
 134 MODULE_DEVICE_TABLE(of, jz4740_wdt_of_matches);
 135 #endif
 136
 137 static int jz4740_wdt_probe(struct platform_device *pdev)
 138 {
 139         struct device *dev = &pdev->dev;
 140         struct jz4740_wdt_drvdata *drvdata;
 141         struct watchdog_device *jz4740_wdt;
 142         long rate;
 143         int ret;
 144
 145         drvdata = devm_kzalloc(dev, sizeof(struct jz4740_wdt_drvdata),
 146                                GFP_KERNEL);
 147         if (!drvdata)
 148                 return -ENOMEM;
 149
 150         drvdata->clk = devm_clk_get(&pdev->dev, "wdt");
 151         if (IS_ERR(drvdata->clk)) {
 152                 dev_err(&pdev->dev, "cannot find WDT clock\n");
 153                 return PTR_ERR(drvdata->clk);
 154         }
 155
 156         /* Set smallest clock possible */
 157         rate = clk_round_rate(drvdata->clk, 1);
 158         if (rate < 0)
 159                 return rate;
 160
 161         ret = clk_set_rate(drvdata->clk, rate);
 162         if (ret)
 163                 return ret;
 164
 165         drvdata->clk_rate = rate;
 166         jz4740_wdt = &drvdata->wdt;
 167         jz4740_wdt->info = &jz4740_wdt_info;
 168         jz4740_wdt->ops = &jz4740_wdt_ops;
 169         jz4740_wdt->min_timeout = 1;
 170         jz4740_wdt->max_timeout = 0xffff / rate;
 171         jz4740_wdt->timeout = clamp(heartbeat,
 172                                     jz4740_wdt->min_timeout,
 173                                     jz4740_wdt->max_timeout);
 174         jz4740_wdt->parent = dev;
 175         watchdog_set_nowayout(jz4740_wdt, nowayout);
 176         watchdog_set_drvdata(jz4740_wdt, drvdata);
 177
 178         drvdata->map = device_node_to_regmap(dev->parent->of_node);
 179         if (IS_ERR(drvdata->map)) {
 180                 dev_err(dev, "regmap not found\n");
 181                 return PTR_ERR(drvdata->map);
 182         }
 183
 184         return devm_watchdog_register_device(dev, &drvdata->wdt);
 185 }
 186
 187 static struct platform_driver jz4740_wdt_driver = {
 188         .probe = jz4740_wdt_probe,
 189         .driver = {
 190                 .name = "jz4740-wdt",
 191                 .of_match_table = of_match_ptr(jz4740_wdt_of_matches),
 192         },
 193 };
 194
 195 module_platform_driver(jz4740_wdt_driver);
 196
 197 MODULE_AUTHOR("Paul Cercueil <paul@crapouillou.net>");
 198 MODULE_DESCRIPTION("jz4740 Watchdog Driver");
 199 MODULE_LICENSE("GPL");
 200 MODULE_ALIAS("platform:jz4740-wdt");