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Linux/drivers/watchdog/da9052_wdt.c

  1 /*
  2  * System monitoring driver for DA9052 PMICs.
  3  *
  4  * Copyright(c) 2012 Dialog Semiconductor Ltd.
  5  *
  6  * Author: Anthony Olech <Anthony.Olech@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/delay.h>
 17 #include <linux/uaccess.h>
 18 #include <linux/platform_device.h>
 19 #include <linux/time.h>
 20 #include <linux/watchdog.h>
 21 #include <linux/types.h>
 22 #include <linux/kernel.h>
 23 #include <linux/jiffies.h>
 24 
 25 #include <linux/mfd/da9052/reg.h>
 26 #include <linux/mfd/da9052/da9052.h>
 27 
 28 #define DA9052_DEF_TIMEOUT      4
 29 #define DA9052_TWDMIN           256
 30 
 31 struct da9052_wdt_data {
 32         struct watchdog_device wdt;
 33         struct da9052 *da9052;
 34         struct kref kref;
 35         unsigned long jpast;
 36 };
 37 
 38 static const struct {
 39         u8 reg_val;
 40         int time;  /* Seconds */
 41 } da9052_wdt_maps[] = {
 42         { 1, 2 },
 43         { 2, 4 },
 44         { 3, 8 },
 45         { 4, 16 },
 46         { 5, 32 },
 47         { 5, 33 },  /* Actual time  32.768s so included both 32s and 33s */
 48         { 6, 65 },
 49         { 6, 66 },  /* Actual time 65.536s so include both, 65s and 66s */
 50         { 7, 131 },
 51 };
 52 
 53 
 54 static void da9052_wdt_release_resources(struct kref *r)
 55 {
 56 }
 57 
 58 static int da9052_wdt_set_timeout(struct watchdog_device *wdt_dev,
 59                                   unsigned int timeout)
 60 {
 61         struct da9052_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
 62         struct da9052 *da9052 = driver_data->da9052;
 63         int ret, i;
 64 
 65         /*
 66          * Disable the Watchdog timer before setting
 67          * new time out.
 68          */
 69         ret = da9052_reg_update(da9052, DA9052_CONTROL_D_REG,
 70                                 DA9052_CONTROLD_TWDSCALE, 0);
 71         if (ret < 0) {
 72                 dev_err(da9052->dev, "Failed to disable watchdog bit, %d\n",
 73                         ret);
 74                 return ret;
 75         }
 76         if (timeout) {
 77                 /*
 78                  * To change the timeout, da9052 needs to
 79                  * be disabled for at least 150 us.
 80                  */
 81                 udelay(150);
 82 
 83                 /* Set the desired timeout */
 84                 for (i = 0; i < ARRAY_SIZE(da9052_wdt_maps); i++)
 85                         if (da9052_wdt_maps[i].time == timeout)
 86                                 break;
 87 
 88                 if (i == ARRAY_SIZE(da9052_wdt_maps))
 89                         ret = -EINVAL;
 90                 else
 91                         ret = da9052_reg_update(da9052, DA9052_CONTROL_D_REG,
 92                                                 DA9052_CONTROLD_TWDSCALE,
 93                                                 da9052_wdt_maps[i].reg_val);
 94                 if (ret < 0) {
 95                         dev_err(da9052->dev,
 96                                 "Failed to update timescale bit, %d\n", ret);
 97                         return ret;
 98                 }
 99 
100                 wdt_dev->timeout = timeout;
101                 driver_data->jpast = jiffies;
102         }
103 
104         return 0;
105 }
106 
107 static void da9052_wdt_ref(struct watchdog_device *wdt_dev)
108 {
109         struct da9052_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
110 
111         kref_get(&driver_data->kref);
112 }
113 
114 static void da9052_wdt_unref(struct watchdog_device *wdt_dev)
115 {
116         struct da9052_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
117 
118         kref_put(&driver_data->kref, da9052_wdt_release_resources);
119 }
120 
121 static int da9052_wdt_start(struct watchdog_device *wdt_dev)
122 {
123         return da9052_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
124 }
125 
126 static int da9052_wdt_stop(struct watchdog_device *wdt_dev)
127 {
128         return da9052_wdt_set_timeout(wdt_dev, 0);
129 }
130 
131 static int da9052_wdt_ping(struct watchdog_device *wdt_dev)
132 {
133         struct da9052_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
134         struct da9052 *da9052 = driver_data->da9052;
135         unsigned long msec, jnow = jiffies;
136         int ret;
137 
138         /*
139          * We have a minimum time for watchdog window called TWDMIN. A write
140          * to the watchdog before this elapsed time should cause an error.
141          */
142         msec = (jnow - driver_data->jpast) * 1000/HZ;
143         if (msec < DA9052_TWDMIN)
144                 mdelay(msec);
145 
146         /* Reset the watchdog timer */
147         ret = da9052_reg_update(da9052, DA9052_CONTROL_D_REG,
148                                 DA9052_CONTROLD_WATCHDOG, 1 << 7);
149         if (ret < 0)
150                 goto err_strobe;
151 
152         /*
153          * FIXME: Reset the watchdog core, in general PMIC
154          * is supposed to do this
155          */
156         ret = da9052_reg_update(da9052, DA9052_CONTROL_D_REG,
157                                 DA9052_CONTROLD_WATCHDOG, 0 << 7);
158 err_strobe:
159         return ret;
160 }
161 
162 static struct watchdog_info da9052_wdt_info = {
163         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
164         .identity       = "DA9052 Watchdog",
165 };
166 
167 static const struct watchdog_ops da9052_wdt_ops = {
168         .owner = THIS_MODULE,
169         .start = da9052_wdt_start,
170         .stop = da9052_wdt_stop,
171         .ping = da9052_wdt_ping,
172         .set_timeout = da9052_wdt_set_timeout,
173         .ref = da9052_wdt_ref,
174         .unref = da9052_wdt_unref,
175 };
176 
177 
178 static int da9052_wdt_probe(struct platform_device *pdev)
179 {
180         struct da9052 *da9052 = dev_get_drvdata(pdev->dev.parent);
181         struct da9052_wdt_data *driver_data;
182         struct watchdog_device *da9052_wdt;
183         int ret;
184 
185         driver_data = devm_kzalloc(&pdev->dev, sizeof(*driver_data),
186                                    GFP_KERNEL);
187         if (!driver_data) {
188                 ret = -ENOMEM;
189                 goto err;
190         }
191         driver_data->da9052 = da9052;
192 
193         da9052_wdt = &driver_data->wdt;
194 
195         da9052_wdt->timeout = DA9052_DEF_TIMEOUT;
196         da9052_wdt->info = &da9052_wdt_info;
197         da9052_wdt->ops = &da9052_wdt_ops;
198         watchdog_set_drvdata(da9052_wdt, driver_data);
199 
200         kref_init(&driver_data->kref);
201 
202         ret = da9052_reg_update(da9052, DA9052_CONTROL_D_REG,
203                                 DA9052_CONTROLD_TWDSCALE, 0);
204         if (ret < 0) {
205                 dev_err(&pdev->dev, "Failed to disable watchdog bits, %d\n",
206                         ret);
207                 goto err;
208         }
209 
210         ret = watchdog_register_device(&driver_data->wdt);
211         if (ret != 0) {
212                 dev_err(da9052->dev, "watchdog_register_device() failed: %d\n",
213                         ret);
214                 goto err;
215         }
216 
217         platform_set_drvdata(pdev, driver_data);
218 err:
219         return ret;
220 }
221 
222 static int da9052_wdt_remove(struct platform_device *pdev)
223 {
224         struct da9052_wdt_data *driver_data = platform_get_drvdata(pdev);
225 
226         watchdog_unregister_device(&driver_data->wdt);
227         kref_put(&driver_data->kref, da9052_wdt_release_resources);
228 
229         return 0;
230 }
231 
232 static struct platform_driver da9052_wdt_driver = {
233         .probe = da9052_wdt_probe,
234         .remove = da9052_wdt_remove,
235         .driver = {
236                 .name   = "da9052-watchdog",
237         },
238 };
239 
240 module_platform_driver(da9052_wdt_driver);
241 
242 MODULE_AUTHOR("Anthony Olech <Anthony.Olech@diasemi.com>");
243 MODULE_DESCRIPTION("DA9052 SM Device Driver");
244 MODULE_LICENSE("GPL");
245 MODULE_ALIAS("platform:da9052-watchdog");
246 

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