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Linux/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         ret = watchdog_register_device(&a21_wdt);
212         if (ret) {
213                 dev_err(&pdev->dev, "Cannot register watchdog device\n");
214                 goto err_register_wd;
215         }
216 
217         dev_set_drvdata(&pdev->dev, drv);
218 
219         dev_info(&pdev->dev, "MEN A21 watchdog timer driver enabled\n");
220 
221         return 0;
222 
223 err_register_wd:
224         mutex_destroy(&drv->lock);
225 
226         return ret;
227 }
228 
229 static int a21_wdt_remove(struct platform_device *pdev)
230 {
231         struct a21_wdt_drv *drv = dev_get_drvdata(&pdev->dev);
232 
233         dev_warn(&pdev->dev,
234                 "Unregistering A21 watchdog driver, board may reboot\n");
235 
236         watchdog_unregister_device(&drv->wdt);
237 
238         mutex_destroy(&drv->lock);
239 
240         return 0;
241 }
242 
243 static void a21_wdt_shutdown(struct platform_device *pdev)
244 {
245         struct a21_wdt_drv *drv = dev_get_drvdata(&pdev->dev);
246 
247         gpio_set_value(drv->gpios[GPIO_WD_ENAB], 0);
248 }
249 
250 static const struct of_device_id a21_wdt_ids[] = {
251         { .compatible = "men,a021-wdt" },
252         { },
253 };
254 
255 static struct platform_driver a21_wdt_driver = {
256         .probe = a21_wdt_probe,
257         .remove = a21_wdt_remove,
258         .shutdown = a21_wdt_shutdown,
259         .driver = {
260                 .name = "a21-watchdog",
261                 .of_match_table = a21_wdt_ids,
262         },
263 };
264 
265 module_platform_driver(a21_wdt_driver);
266 
267 MODULE_AUTHOR("MEN Mikro Elektronik");
268 MODULE_DESCRIPTION("MEN A21 Watchdog");
269 MODULE_LICENSE("GPL");
270 MODULE_ALIAS("platform:a21-watchdog");
271 

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