drivers/watchdog/mena21_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Watchdog driver for the A21 VME CPU Boards
   4  *
   5  * Copyright (C) 2013 MEN Mikro Elektronik Nuernberg GmbH
   6  *
   7  */
   8 #include <linux/module.h>
   9 #include <linux/moduleparam.h>
  10 #include <linux/types.h>
  11 #include <linux/kernel.h>
  12 #include <linux/slab.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/watchdog.h>
  15 #include <linux/uaccess.h>
  16 #include <linux/gpio/consumer.h>
  17 #include <linux/delay.h>
  18 #include <linux/bitops.h>
  19 #include <linux/of.h>
  20
  21 #define NUM_GPIOS 6
  22
  23 enum a21_wdt_gpios {
  24         GPIO_WD_ENAB,
  25         GPIO_WD_FAST,
  26         GPIO_WD_TRIG,
  27         GPIO_WD_RST0,
  28         GPIO_WD_RST1,
  29         GPIO_WD_RST2,
  30 };
  31
  32 struct a21_wdt_drv {
  33         struct watchdog_device wdt;
  34         struct gpio_desc *gpios[NUM_GPIOS];
  35 };
  36
  37 static bool nowayout = WATCHDOG_NOWAYOUT;
  38 module_param(nowayout, bool, 0);
  39 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  40                             __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  41
  42 static unsigned int a21_wdt_get_bootstatus(struct a21_wdt_drv *drv)
  43 {
  44         int reset = 0;
  45
  46         reset |= gpiod_get_value(drv->gpios[GPIO_WD_RST0]) ? (1 << 0) : 0;
  47         reset |= gpiod_get_value(drv->gpios[GPIO_WD_RST1]) ? (1 << 1) : 0;
  48         reset |= gpiod_get_value(drv->gpios[GPIO_WD_RST2]) ? (1 << 2) : 0;
  49
  50         return reset;
  51 }
  52
  53 static int a21_wdt_start(struct watchdog_device *wdt)
  54 {
  55         struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
  56
  57         gpiod_set_value(drv->gpios[GPIO_WD_ENAB], 1);
  58
  59         return 0;
  60 }
  61
  62 static int a21_wdt_stop(struct watchdog_device *wdt)
  63 {
  64         struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
  65
  66         gpiod_set_value(drv->gpios[GPIO_WD_ENAB], 0);
  67
  68         return 0;
  69 }
  70
  71 static int a21_wdt_ping(struct watchdog_device *wdt)
  72 {
  73         struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
  74
  75         gpiod_set_value(drv->gpios[GPIO_WD_TRIG], 0);
  76         ndelay(10);
  77         gpiod_set_value(drv->gpios[GPIO_WD_TRIG], 1);
  78
  79         return 0;
  80 }
  81
  82 static int a21_wdt_set_timeout(struct watchdog_device *wdt,
  83                                unsigned int timeout)
  84 {
  85         struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
  86
  87         if (timeout != 1 && timeout != 30) {
  88                 dev_err(wdt->parent, "Only 1 and 30 allowed as timeout\n");
  89                 return -EINVAL;
  90         }
  91
  92         if (timeout == 30 && wdt->timeout == 1) {
  93                 dev_err(wdt->parent,
  94                         "Transition from fast to slow mode not allowed\n");
  95                 return -EINVAL;
  96         }
  97
  98         if (timeout == 1)
  99                 gpiod_set_value(drv->gpios[GPIO_WD_FAST], 1);
 100         else
 101                 gpiod_set_value(drv->gpios[GPIO_WD_FAST], 0);
 102
 103         wdt->timeout = timeout;
 104
 105         return 0;
 106 }
 107
 108 static const struct watchdog_info a21_wdt_info = {
 109         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 110         .identity = "MEN A21 Watchdog",
 111 };
 112
 113 static const struct watchdog_ops a21_wdt_ops = {
 114         .owner = THIS_MODULE,
 115         .start = a21_wdt_start,
 116         .stop = a21_wdt_stop,
 117         .ping = a21_wdt_ping,
 118         .set_timeout = a21_wdt_set_timeout,
 119 };
 120
 121 static struct watchdog_device a21_wdt = {
 122         .info = &a21_wdt_info,
 123         .ops = &a21_wdt_ops,
 124         .min_timeout = 1,
 125         .max_timeout = 30,
 126 };
 127
 128 static int a21_wdt_probe(struct platform_device *pdev)
 129 {
 130         struct device *dev = &pdev->dev;
 131         struct a21_wdt_drv *drv;
 132         unsigned int reset = 0;
 133         int num_gpios;
 134         int ret;
 135         int i;
 136
 137         drv = devm_kzalloc(dev, sizeof(struct a21_wdt_drv), GFP_KERNEL);
 138         if (!drv)
 139                 return -ENOMEM;
 140
 141         num_gpios = gpiod_count(dev, NULL);
 142         if (num_gpios != NUM_GPIOS) {
 143                 dev_err(dev, "gpios DT property wrong, got %d want %d",
 144                         num_gpios, NUM_GPIOS);
 145                 return -ENODEV;
 146         }
 147
 148         /* Request the used GPIOs */
 149         for (i = 0; i < num_gpios; i++) {
 150                 enum gpiod_flags gflags;
 151
 152                 if (i < GPIO_WD_RST0)
 153                         gflags = GPIOD_ASIS;
 154                 else
 155                         gflags = GPIOD_IN;
 156                 drv->gpios[i] = devm_gpiod_get_index(dev, NULL, i, gflags);
 157                 if (IS_ERR(drv->gpios[i]))
 158                         return PTR_ERR(drv->gpios[i]);
 159
 160                 gpiod_set_consumer_name(drv->gpios[i], "MEN A21 Watchdog");
 161
 162                 /*
 163                  * Retrieve the initial value from the GPIOs that should be
 164                  * output, then set up the line as output with that value.
 165                  */
 166                 if (i < GPIO_WD_RST0) {
 167                         int val;
 168
 169                         val = gpiod_get_value(drv->gpios[i]);
 170                         gpiod_direction_output(drv->gpios[i], val);
 171                 }
 172         }
 173
 174         watchdog_init_timeout(&a21_wdt, 30, dev);
 175         watchdog_set_nowayout(&a21_wdt, nowayout);
 176         watchdog_set_drvdata(&a21_wdt, drv);
 177         a21_wdt.parent = dev;
 178
 179         reset = a21_wdt_get_bootstatus(drv);
 180         if (reset == 2)
 181                 a21_wdt.bootstatus |= WDIOF_EXTERN1;
 182         else if (reset == 4)
 183                 a21_wdt.bootstatus |= WDIOF_CARDRESET;
 184         else if (reset == 5)
 185                 a21_wdt.bootstatus |= WDIOF_POWERUNDER;
 186         else if (reset == 7)
 187                 a21_wdt.bootstatus |= WDIOF_EXTERN2;
 188
 189         drv->wdt = a21_wdt;
 190         dev_set_drvdata(dev, drv);
 191
 192         ret = devm_watchdog_register_device(dev, &a21_wdt);
 193         if (ret)
 194                 return ret;
 195
 196         dev_info(dev, "MEN A21 watchdog timer driver enabled\n");
 197
 198         return 0;
 199 }
 200
 201 static void a21_wdt_shutdown(struct platform_device *pdev)
 202 {
 203         struct a21_wdt_drv *drv = dev_get_drvdata(&pdev->dev);
 204
 205         gpiod_set_value(drv->gpios[GPIO_WD_ENAB], 0);
 206 }
 207
 208 static const struct of_device_id a21_wdt_ids[] = {
 209         { .compatible = "men,a021-wdt" },
 210         { },
 211 };
 212 MODULE_DEVICE_TABLE(of, a21_wdt_ids);
 213
 214 static struct platform_driver a21_wdt_driver = {
 215         .probe = a21_wdt_probe,
 216         .shutdown = a21_wdt_shutdown,
 217         .driver = {
 218                 .name = "a21-watchdog",
 219                 .of_match_table = a21_wdt_ids,
 220         },
 221 };
 222
 223 module_platform_driver(a21_wdt_driver);
 224
 225 MODULE_AUTHOR("MEN Mikro Elektronik");
 226 MODULE_DESCRIPTION("MEN A21 Watchdog");
 227 MODULE_LICENSE("GPL");
 228 MODULE_ALIAS("platform:a21-watchdog");