drivers/watchdog/mena21_wdt.c

   1 /*
   2  * Watchdog driver for the A21 VME CPU Boards
   3  *
   4  * Copyright (C) 2013 MEN Mikro Elektronik Nuernberg GmbH
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation
   9  */
  10 #include <linux/module.h>
  11 #include <linux/moduleparam.h>
  12 #include <linux/types.h>
  13 #include <linux/kernel.h>
  14 #include <linux/slab.h>
  15 #include <linux/platform_device.h>
  16 #include <linux/watchdog.h>
  17 #include <linux/uaccess.h>
  18 #include <linux/gpio.h>
  19 #include <linux/of_gpio.h>
  20 #include <linux/delay.h>
  21 #include <linux/bitops.h>
  22
  23 #define NUM_GPIOS 6
  24
  25 enum a21_wdt_gpios {
  26         GPIO_WD_ENAB,
  27         GPIO_WD_FAST,
  28         GPIO_WD_TRIG,
  29         GPIO_WD_RST0,
  30         GPIO_WD_RST1,
  31         GPIO_WD_RST2,
  32 };
  33
  34 struct a21_wdt_drv {
  35         struct watchdog_device wdt;
  36         struct mutex lock;
  37         unsigned gpios[NUM_GPIOS];
  38 };
  39
  40 static bool nowayout = WATCHDOG_NOWAYOUT;
  41 module_param(nowayout, bool, 0);
  42 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  43                             __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  44
  45 static unsigned int a21_wdt_get_bootstatus(struct a21_wdt_drv *drv)
  46 {
  47         int reset = 0;
  48
  49         reset |= gpio_get_value(drv->gpios[GPIO_WD_RST0]) ? (1 << 0) : 0;
  50         reset |= gpio_get_value(drv->gpios[GPIO_WD_RST1]) ? (1 << 1) : 0;
  51         reset |= gpio_get_value(drv->gpios[GPIO_WD_RST2]) ? (1 << 2) : 0;
  52
  53         return reset;
  54 }
  55
  56 static int a21_wdt_start(struct watchdog_device *wdt)
  57 {
  58         struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
  59
  60         mutex_lock(&drv->lock);
  61
  62         gpio_set_value(drv->gpios[GPIO_WD_ENAB], 1);
  63
  64         mutex_unlock(&drv->lock);
  65
  66         return 0;
  67 }
  68
  69 static int a21_wdt_stop(struct watchdog_device *wdt)
  70 {
  71         struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
  72
  73         mutex_lock(&drv->lock);
  74
  75         gpio_set_value(drv->gpios[GPIO_WD_ENAB], 0);
  76
  77         mutex_unlock(&drv->lock);
  78
  79         return 0;
  80 }
  81
  82 static int a21_wdt_ping(struct watchdog_device *wdt)
  83 {
  84         struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
  85
  86         mutex_lock(&drv->lock);
  87
  88         gpio_set_value(drv->gpios[GPIO_WD_TRIG], 0);
  89         ndelay(10);
  90         gpio_set_value(drv->gpios[GPIO_WD_TRIG], 1);
  91
  92         mutex_unlock(&drv->lock);
  93
  94         return 0;
  95 }
  96
  97 static int a21_wdt_set_timeout(struct watchdog_device *wdt,
  98                                unsigned int timeout)
  99 {
 100         struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
 101
 102         if (timeout != 1 && timeout != 30) {
 103                 dev_err(wdt->dev, "Only 1 and 30 allowed as timeout\n");
 104                 return -EINVAL;
 105         }
 106
 107         if (timeout == 30 && wdt->timeout == 1) {
 108                 dev_err(wdt->dev,
 109                         "Transition from fast to slow mode not allowed\n");
 110                 return -EINVAL;
 111         }
 112
 113         mutex_lock(&drv->lock);
 114
 115         if (timeout == 1)
 116                 gpio_set_value(drv->gpios[GPIO_WD_FAST], 1);
 117         else
 118                 gpio_set_value(drv->gpios[GPIO_WD_FAST], 0);
 119
 120         wdt->timeout = timeout;
 121
 122         mutex_unlock(&drv->lock);
 123
 124         return 0;
 125 }
 126
 127 static const struct watchdog_info a21_wdt_info = {
 128         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 129         .identity = "MEN A21 Watchdog",
 130 };
 131
 132 static const struct watchdog_ops a21_wdt_ops = {
 133         .owner = THIS_MODULE,
 134         .start = a21_wdt_start,
 135         .stop = a21_wdt_stop,
 136         .ping = a21_wdt_ping,
 137         .set_timeout = a21_wdt_set_timeout,
 138 };
 139
 140 static struct watchdog_device a21_wdt = {
 141         .info = &a21_wdt_info,
 142         .ops = &a21_wdt_ops,
 143         .min_timeout = 1,
 144         .max_timeout = 30,
 145 };
 146
 147 static int a21_wdt_probe(struct platform_device *pdev)
 148 {
 149         struct device_node *node;
 150         struct a21_wdt_drv *drv;
 151         unsigned int reset = 0;
 152         int num_gpios;
 153         int ret;
 154         int i;
 155
 156         drv = devm_kzalloc(&pdev->dev, sizeof(struct a21_wdt_drv), GFP_KERNEL);
 157         if (!drv)
 158                 return -ENOMEM;
 159
 160         /* Fill GPIO pin array */
 161         node = pdev->dev.of_node;
 162
 163         num_gpios = of_gpio_count(node);
 164         if (num_gpios != NUM_GPIOS) {
 165                 dev_err(&pdev->dev, "gpios DT property wrong, got %d want %d",
 166                         num_gpios, NUM_GPIOS);
 167                 return -ENODEV;
 168         }
 169
 170         for (i = 0; i < num_gpios; i++) {
 171                 int val;
 172
 173                 val = of_get_gpio(node, i);
 174                 if (val < 0)
 175                         return val;
 176
 177                 drv->gpios[i] = val;
 178         }
 179
 180         /* Request the used GPIOs */
 181         for (i = 0; i < num_gpios; i++) {
 182                 ret = devm_gpio_request(&pdev->dev, drv->gpios[i],
 183                                         "MEN A21 Watchdog");
 184                 if (ret)
 185                         return ret;
 186
 187                 if (i < GPIO_WD_RST0)
 188                         ret = gpio_direction_output(drv->gpios[i],
 189                                                 gpio_get_value(drv->gpios[i]));
 190                 else            /* GPIO_WD_RST[0..2] are inputs */
 191                         ret = gpio_direction_input(drv->gpios[i]);
 192                 if (ret)
 193                         return ret;
 194         }
 195
 196         mutex_init(&drv->lock);
 197         watchdog_init_timeout(&a21_wdt, 30, &pdev->dev);
 198         watchdog_set_nowayout(&a21_wdt, nowayout);
 199         watchdog_set_drvdata(&a21_wdt, drv);
 200
 201         reset = a21_wdt_get_bootstatus(drv);
 202         if (reset == 2)
 203                 a21_wdt.bootstatus |= WDIOF_EXTERN1;
 204         else if (reset == 4)
 205                 a21_wdt.bootstatus |= WDIOF_CARDRESET;
 206         else if (reset == 5)
 207                 a21_wdt.bootstatus |= WDIOF_POWERUNDER;
 208         else if (reset == 7)
 209                 a21_wdt.bootstatus |= WDIOF_EXTERN2;
 210
 211         drv->wdt = a21_wdt;
 212         dev_set_drvdata(&pdev->dev, drv);
 213
 214         ret = watchdog_register_device(&a21_wdt);
 215         if (ret) {
 216                 dev_err(&pdev->dev, "Cannot register watchdog device\n");
 217                 goto err_register_wd;
 218         }
 219
 220         dev_info(&pdev->dev, "MEN A21 watchdog timer driver enabled\n");
 221
 222         return 0;
 223
 224 err_register_wd:
 225         mutex_destroy(&drv->lock);
 226
 227         return ret;
 228 }
 229
 230 static int a21_wdt_remove(struct platform_device *pdev)
 231 {
 232         struct a21_wdt_drv *drv = dev_get_drvdata(&pdev->dev);
 233
 234         dev_warn(&pdev->dev,
 235                 "Unregistering A21 watchdog driver, board may reboot\n");
 236
 237         watchdog_unregister_device(&drv->wdt);
 238
 239         mutex_destroy(&drv->lock);
 240
 241         return 0;
 242 }
 243
 244 static void a21_wdt_shutdown(struct platform_device *pdev)
 245 {
 246         struct a21_wdt_drv *drv = dev_get_drvdata(&pdev->dev);
 247
 248         gpio_set_value(drv->gpios[GPIO_WD_ENAB], 0);
 249 }
 250
 251 static const struct of_device_id a21_wdt_ids[] = {
 252         { .compatible = "men,a021-wdt" },
 253         { },
 254 };
 255
 256 static struct platform_driver a21_wdt_driver = {
 257         .probe = a21_wdt_probe,
 258         .remove = a21_wdt_remove,
 259         .shutdown = a21_wdt_shutdown,
 260         .driver = {
 261                 .name = "a21-watchdog",
 262                 .of_match_table = a21_wdt_ids,
 263         },
 264 };
 265
 266 module_platform_driver(a21_wdt_driver);
 267
 268 MODULE_AUTHOR("MEN Mikro Elektronik");
 269 MODULE_DESCRIPTION("MEN A21 Watchdog");
 270 MODULE_LICENSE("GPL");
 271 MODULE_ALIAS("platform:a21-watchdog");