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Linux/drivers/watchdog/da9055_wdt.c

  1 /*
  2  * System monitoring driver for DA9055 PMICs.
  3  *
  4  * Copyright(c) 2012 Dialog Semiconductor Ltd.
  5  *
  6  * Author: David Dajun Chen <dchen@diasemi.com>
  7  *
  8  * This program is free software; you can redistribute it and/or modify
  9  * it under the terms of the GNU General Public License as published by
 10  * the Free Software Foundation; either version 2 of the License, or
 11  * (at your option) any later version.
 12  *
 13  */
 14 
 15 #include <linux/module.h>
 16 #include <linux/types.h>
 17 #include <linux/kernel.h>
 18 #include <linux/slab.h>
 19 #include <linux/platform_device.h>
 20 #include <linux/watchdog.h>
 21 #include <linux/delay.h>
 22 
 23 #include <linux/mfd/da9055/core.h>
 24 #include <linux/mfd/da9055/reg.h>
 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 #define DA9055_DEF_TIMEOUT      4
 33 #define DA9055_TWDMIN           256
 34 
 35 struct da9055_wdt_data {
 36         struct watchdog_device wdt;
 37         struct da9055 *da9055;
 38         struct kref kref;
 39 };
 40 
 41 static const struct {
 42         u8 reg_val;
 43         int user_time;  /* In seconds */
 44 } da9055_wdt_maps[] = {
 45         { 0, 0 },
 46         { 1, 2 },
 47         { 2, 4 },
 48         { 3, 8 },
 49         { 4, 16 },
 50         { 5, 32 },
 51         { 5, 33 },  /* Actual time  32.768s so included both 32s and 33s */
 52         { 6, 65 },
 53         { 6, 66 },  /* Actual time 65.536s so include both, 65s and 66s */
 54         { 7, 131 },
 55 };
 56 
 57 static int da9055_wdt_set_timeout(struct watchdog_device *wdt_dev,
 58                                   unsigned int timeout)
 59 {
 60         struct da9055_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
 61         struct da9055 *da9055 = driver_data->da9055;
 62         int ret, i;
 63 
 64         for (i = 0; i < ARRAY_SIZE(da9055_wdt_maps); i++)
 65                 if (da9055_wdt_maps[i].user_time == timeout)
 66                         break;
 67 
 68         if (i == ARRAY_SIZE(da9055_wdt_maps))
 69                 ret = -EINVAL;
 70         else
 71                 ret = da9055_reg_update(da9055, DA9055_REG_CONTROL_B,
 72                                         DA9055_TWDSCALE_MASK,
 73                                         da9055_wdt_maps[i].reg_val <<
 74                                         DA9055_TWDSCALE_SHIFT);
 75         if (ret < 0) {
 76                 dev_err(da9055->dev,
 77                         "Failed to update timescale bit, %d\n", ret);
 78                 return ret;
 79         }
 80 
 81         wdt_dev->timeout = timeout;
 82 
 83         return 0;
 84 }
 85 
 86 static int da9055_wdt_ping(struct watchdog_device *wdt_dev)
 87 {
 88         struct da9055_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
 89         struct da9055 *da9055 = driver_data->da9055;
 90 
 91         /*
 92          * We have a minimum time for watchdog window called TWDMIN. A write
 93          * to the watchdog before this elapsed time will cause an error.
 94          */
 95         mdelay(DA9055_TWDMIN);
 96 
 97         /* Reset the watchdog timer */
 98         return da9055_reg_update(da9055, DA9055_REG_CONTROL_E,
 99                                  DA9055_WATCHDOG_MASK, 1);
100 }
101 
102 static void da9055_wdt_release_resources(struct kref *r)
103 {
104 }
105 
106 static void da9055_wdt_ref(struct watchdog_device *wdt_dev)
107 {
108         struct da9055_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
109 
110         kref_get(&driver_data->kref);
111 }
112 
113 static void da9055_wdt_unref(struct watchdog_device *wdt_dev)
114 {
115         struct da9055_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
116 
117         kref_put(&driver_data->kref, da9055_wdt_release_resources);
118 }
119 
120 static int da9055_wdt_start(struct watchdog_device *wdt_dev)
121 {
122         return da9055_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
123 }
124 
125 static int da9055_wdt_stop(struct watchdog_device *wdt_dev)
126 {
127         return da9055_wdt_set_timeout(wdt_dev, 0);
128 }
129 
130 static struct watchdog_info da9055_wdt_info = {
131         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
132         .identity       = "DA9055 Watchdog",
133 };
134 
135 static const struct watchdog_ops da9055_wdt_ops = {
136         .owner = THIS_MODULE,
137         .start = da9055_wdt_start,
138         .stop = da9055_wdt_stop,
139         .ping = da9055_wdt_ping,
140         .set_timeout = da9055_wdt_set_timeout,
141         .ref = da9055_wdt_ref,
142         .unref = da9055_wdt_unref,
143 };
144 
145 static int da9055_wdt_probe(struct platform_device *pdev)
146 {
147         struct da9055 *da9055 = dev_get_drvdata(pdev->dev.parent);
148         struct da9055_wdt_data *driver_data;
149         struct watchdog_device *da9055_wdt;
150         int ret;
151 
152         driver_data = devm_kzalloc(&pdev->dev, sizeof(*driver_data),
153                                    GFP_KERNEL);
154         if (!driver_data)
155                 return -ENOMEM;
156 
157         driver_data->da9055 = da9055;
158 
159         da9055_wdt = &driver_data->wdt;
160 
161         da9055_wdt->timeout = DA9055_DEF_TIMEOUT;
162         da9055_wdt->info = &da9055_wdt_info;
163         da9055_wdt->ops = &da9055_wdt_ops;
164         watchdog_set_nowayout(da9055_wdt, nowayout);
165         watchdog_set_drvdata(da9055_wdt, driver_data);
166 
167         kref_init(&driver_data->kref);
168 
169         ret = da9055_wdt_stop(da9055_wdt);
170         if (ret < 0) {
171                 dev_err(&pdev->dev, "Failed to stop watchdog, %d\n", ret);
172                 goto err;
173         }
174 
175         platform_set_drvdata(pdev, driver_data);
176 
177         ret = watchdog_register_device(&driver_data->wdt);
178         if (ret != 0)
179                 dev_err(da9055->dev, "watchdog_register_device() failed: %d\n",
180                         ret);
181 
182 err:
183         return ret;
184 }
185 
186 static int da9055_wdt_remove(struct platform_device *pdev)
187 {
188         struct da9055_wdt_data *driver_data = platform_get_drvdata(pdev);
189 
190         watchdog_unregister_device(&driver_data->wdt);
191         kref_put(&driver_data->kref, da9055_wdt_release_resources);
192 
193         return 0;
194 }
195 
196 static struct platform_driver da9055_wdt_driver = {
197         .probe = da9055_wdt_probe,
198         .remove = da9055_wdt_remove,
199         .driver = {
200                 .name   = "da9055-watchdog",
201         },
202 };
203 
204 module_platform_driver(da9055_wdt_driver);
205 
206 MODULE_AUTHOR("David Dajun Chen <dchen@diasemi.com>");
207 MODULE_DESCRIPTION("DA9055 watchdog");
208 MODULE_LICENSE("GPL");
209 MODULE_ALIAS("platform:da9055-watchdog");
210 

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