drivers/watchdog/sl28cpld_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * sl28cpld watchdog driver
   4  *
   5  * Copyright 2020 Kontron Europe GmbH
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/mod_devicetable.h>
  10 #include <linux/module.h>
  11 #include <linux/platform_device.h>
  12 #include <linux/property.h>
  13 #include <linux/regmap.h>
  14 #include <linux/watchdog.h>
  15
  16 /*
  17  * Watchdog timer block registers.
  18  */
  19 #define WDT_CTRL                        0x00
  20 #define  WDT_CTRL_EN                    BIT(0)
  21 #define  WDT_CTRL_LOCK                  BIT(2)
  22 #define  WDT_CTRL_ASSERT_SYS_RESET      BIT(6)
  23 #define  WDT_CTRL_ASSERT_WDT_TIMEOUT    BIT(7)
  24 #define WDT_TIMEOUT                     0x01
  25 #define WDT_KICK                        0x02
  26 #define  WDT_KICK_VALUE                 0x6b
  27 #define WDT_COUNT                       0x03
  28
  29 #define WDT_DEFAULT_TIMEOUT             10
  30
  31 static bool nowayout = WATCHDOG_NOWAYOUT;
  32 module_param(nowayout, bool, 0);
  33 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  34                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  35
  36 static int timeout;
  37 module_param(timeout, int, 0);
  38 MODULE_PARM_DESC(timeout, "Initial watchdog timeout in seconds");
  39
  40 struct sl28cpld_wdt {
  41         struct watchdog_device wdd;
  42         struct regmap *regmap;
  43         u32 offset;
  44         bool assert_wdt_timeout;
  45 };
  46
  47 static int sl28cpld_wdt_ping(struct watchdog_device *wdd)
  48 {
  49         struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
  50
  51         return regmap_write(wdt->regmap, wdt->offset + WDT_KICK,
  52                             WDT_KICK_VALUE);
  53 }
  54
  55 static int sl28cpld_wdt_start(struct watchdog_device *wdd)
  56 {
  57         struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
  58         unsigned int val;
  59
  60         val = WDT_CTRL_EN | WDT_CTRL_ASSERT_SYS_RESET;
  61         if (wdt->assert_wdt_timeout)
  62                 val |= WDT_CTRL_ASSERT_WDT_TIMEOUT;
  63         if (nowayout)
  64                 val |= WDT_CTRL_LOCK;
  65
  66         return regmap_update_bits(wdt->regmap, wdt->offset + WDT_CTRL,
  67                                   val, val);
  68 }
  69
  70 static int sl28cpld_wdt_stop(struct watchdog_device *wdd)
  71 {
  72         struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
  73
  74         return regmap_update_bits(wdt->regmap, wdt->offset + WDT_CTRL,
  75                                   WDT_CTRL_EN, 0);
  76 }
  77
  78 static unsigned int sl28cpld_wdt_get_timeleft(struct watchdog_device *wdd)
  79 {
  80         struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
  81         unsigned int val;
  82         int ret;
  83
  84         ret = regmap_read(wdt->regmap, wdt->offset + WDT_COUNT, &val);
  85         if (ret)
  86                 return 0;
  87
  88         return val;
  89 }
  90
  91 static int sl28cpld_wdt_set_timeout(struct watchdog_device *wdd,
  92                                     unsigned int timeout)
  93 {
  94         struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
  95         int ret;
  96
  97         ret = regmap_write(wdt->regmap, wdt->offset + WDT_TIMEOUT, timeout);
  98         if (ret)
  99                 return ret;
 100
 101         wdd->timeout = timeout;
 102
 103         return 0;
 104 }
 105
 106 static const struct watchdog_info sl28cpld_wdt_info = {
 107         .options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 108         .identity = "sl28cpld watchdog",
 109 };
 110
 111 static const struct watchdog_ops sl28cpld_wdt_ops = {
 112         .owner = THIS_MODULE,
 113         .start = sl28cpld_wdt_start,
 114         .stop = sl28cpld_wdt_stop,
 115         .ping = sl28cpld_wdt_ping,
 116         .set_timeout = sl28cpld_wdt_set_timeout,
 117         .get_timeleft = sl28cpld_wdt_get_timeleft,
 118 };
 119
 120 static int sl28cpld_wdt_probe(struct platform_device *pdev)
 121 {
 122         struct watchdog_device *wdd;
 123         struct sl28cpld_wdt *wdt;
 124         unsigned int status;
 125         unsigned int val;
 126         int ret;
 127
 128         if (!pdev->dev.parent)
 129                 return -ENODEV;
 130
 131         wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
 132         if (!wdt)
 133                 return -ENOMEM;
 134
 135         wdt->regmap = dev_get_regmap(pdev->dev.parent, NULL);
 136         if (!wdt->regmap)
 137                 return -ENODEV;
 138
 139         ret = device_property_read_u32(&pdev->dev, "reg", &wdt->offset);
 140         if (ret)
 141                 return -EINVAL;
 142
 143         wdt->assert_wdt_timeout = device_property_read_bool(&pdev->dev,
 144                                                             "kontron,assert-wdt-timeout-pin");
 145
 146         /* initialize struct watchdog_device */
 147         wdd = &wdt->wdd;
 148         wdd->parent = &pdev->dev;
 149         wdd->info = &sl28cpld_wdt_info;
 150         wdd->ops = &sl28cpld_wdt_ops;
 151         wdd->min_timeout = 1;
 152         wdd->max_timeout = 255;
 153
 154         watchdog_set_drvdata(wdd, wdt);
 155         watchdog_stop_on_reboot(wdd);
 156
 157         /*
 158          * Read the status early, in case of an error, we haven't modified the
 159          * hardware.
 160          */
 161         ret = regmap_read(wdt->regmap, wdt->offset + WDT_CTRL, &status);
 162         if (ret)
 163                 return ret;
 164
 165         /*
 166          * Initial timeout value, may be overwritten by device tree or module
 167          * parameter in watchdog_init_timeout().
 168          *
 169          * Reading a zero here means that either the hardware has a default
 170          * value of zero (which is very unlikely and definitely a hardware
 171          * bug) or the bootloader set it to zero. In any case, we handle
 172          * this case gracefully and set out own timeout.
 173          */
 174         ret = regmap_read(wdt->regmap, wdt->offset + WDT_TIMEOUT, &val);
 175         if (ret)
 176                 return ret;
 177
 178         if (val)
 179                 wdd->timeout = val;
 180         else
 181                 wdd->timeout = WDT_DEFAULT_TIMEOUT;
 182
 183         watchdog_init_timeout(wdd, timeout, &pdev->dev);
 184         sl28cpld_wdt_set_timeout(wdd, wdd->timeout);
 185
 186         /* if the watchdog is locked, we set nowayout */
 187         if (status & WDT_CTRL_LOCK)
 188                 nowayout = true;
 189         watchdog_set_nowayout(wdd, nowayout);
 190
 191         /*
 192          * If watchdog is already running, keep it enabled, but make
 193          * sure its mode is set correctly.
 194          */
 195         if (status & WDT_CTRL_EN) {
 196                 sl28cpld_wdt_start(wdd);
 197                 set_bit(WDOG_HW_RUNNING, &wdd->status);
 198         }
 199
 200         ret = devm_watchdog_register_device(&pdev->dev, wdd);
 201         if (ret < 0) {
 202                 dev_err(&pdev->dev, "failed to register watchdog device\n");
 203                 return ret;
 204         }
 205
 206         dev_info(&pdev->dev, "initial timeout %d sec%s\n",
 207                  wdd->timeout, nowayout ? ", nowayout" : "");
 208
 209         return 0;
 210 }
 211
 212 static const struct of_device_id sl28cpld_wdt_of_match[] = {
 213         { .compatible = "kontron,sl28cpld-wdt" },
 214         {}
 215 };
 216 MODULE_DEVICE_TABLE(of, sl28cpld_wdt_of_match);
 217
 218 static struct platform_driver sl28cpld_wdt_driver = {
 219         .probe = sl28cpld_wdt_probe,
 220         .driver = {
 221                 .name = "sl28cpld-wdt",
 222                 .of_match_table = sl28cpld_wdt_of_match,
 223         },
 224 };
 225 module_platform_driver(sl28cpld_wdt_driver);
 226
 227 MODULE_DESCRIPTION("sl28cpld Watchdog Driver");
 228 MODULE_AUTHOR("Michael Walle <michael@walle.cc>");
 229 MODULE_LICENSE("GPL");