xref: /linux/drivers/watchdog/twl4030_wdt.c (revision 0d456bad36d42d16022be045c8a53ddbb59ee478)
1 /*
2  * Copyright (C) Nokia Corporation
3  *
4  * Written by Timo Kokkonen <timo.t.kokkonen at nokia.com>
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation; either version 2 of the License, or
9  * (at your option) any later version.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with this program; if not, write to the Free Software
18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19  */
20 
21 #include <linux/module.h>
22 #include <linux/types.h>
23 #include <linux/slab.h>
24 #include <linux/kernel.h>
25 #include <linux/fs.h>
26 #include <linux/watchdog.h>
27 #include <linux/platform_device.h>
28 #include <linux/miscdevice.h>
29 #include <linux/uaccess.h>
30 #include <linux/i2c/twl.h>
31 
32 #define TWL4030_WATCHDOG_CFG_REG_OFFS	0x3
33 
34 #define TWL4030_WDT_STATE_OPEN		0x1
35 #define TWL4030_WDT_STATE_ACTIVE	0x8
36 
37 static struct platform_device *twl4030_wdt_dev;
38 
39 struct twl4030_wdt {
40 	struct miscdevice	miscdev;
41 	int			timer_margin;
42 	unsigned long		state;
43 };
44 
45 static bool nowayout = WATCHDOG_NOWAYOUT;
46 module_param(nowayout, bool, 0);
47 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
48 	"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
49 
50 static int twl4030_wdt_write(unsigned char val)
51 {
52 	return twl_i2c_write_u8(TWL4030_MODULE_PM_RECEIVER, val,
53 					TWL4030_WATCHDOG_CFG_REG_OFFS);
54 }
55 
56 static int twl4030_wdt_enable(struct twl4030_wdt *wdt)
57 {
58 	return twl4030_wdt_write(wdt->timer_margin + 1);
59 }
60 
61 static int twl4030_wdt_disable(struct twl4030_wdt *wdt)
62 {
63 	return twl4030_wdt_write(0);
64 }
65 
66 static int twl4030_wdt_set_timeout(struct twl4030_wdt *wdt, int timeout)
67 {
68 	if (timeout < 0 || timeout > 30) {
69 		dev_warn(wdt->miscdev.parent,
70 			"Timeout can only be in the range [0-30] seconds");
71 		return -EINVAL;
72 	}
73 	wdt->timer_margin = timeout;
74 	return twl4030_wdt_enable(wdt);
75 }
76 
77 static ssize_t twl4030_wdt_write_fop(struct file *file,
78 		const char __user *data, size_t len, loff_t *ppos)
79 {
80 	struct twl4030_wdt *wdt = file->private_data;
81 
82 	if (len)
83 		twl4030_wdt_enable(wdt);
84 
85 	return len;
86 }
87 
88 static long twl4030_wdt_ioctl(struct file *file,
89 		unsigned int cmd, unsigned long arg)
90 {
91 	void __user *argp = (void __user *)arg;
92 	int __user *p = argp;
93 	int new_margin;
94 	struct twl4030_wdt *wdt = file->private_data;
95 
96 	static const struct watchdog_info twl4030_wd_ident = {
97 		.identity = "TWL4030 Watchdog",
98 		.options = WDIOF_SETTIMEOUT,
99 		.firmware_version = 0,
100 	};
101 
102 	switch (cmd) {
103 	case WDIOC_GETSUPPORT:
104 		return copy_to_user(argp, &twl4030_wd_ident,
105 				sizeof(twl4030_wd_ident)) ? -EFAULT : 0;
106 
107 	case WDIOC_GETSTATUS:
108 	case WDIOC_GETBOOTSTATUS:
109 		return put_user(0, p);
110 
111 	case WDIOC_KEEPALIVE:
112 		twl4030_wdt_enable(wdt);
113 		break;
114 
115 	case WDIOC_SETTIMEOUT:
116 		if (get_user(new_margin, p))
117 			return -EFAULT;
118 		if (twl4030_wdt_set_timeout(wdt, new_margin))
119 			return -EINVAL;
120 		return put_user(wdt->timer_margin, p);
121 
122 	case WDIOC_GETTIMEOUT:
123 		return put_user(wdt->timer_margin, p);
124 
125 	default:
126 		return -ENOTTY;
127 	}
128 
129 	return 0;
130 }
131 
132 static int twl4030_wdt_open(struct inode *inode, struct file *file)
133 {
134 	struct twl4030_wdt *wdt = platform_get_drvdata(twl4030_wdt_dev);
135 
136 	/* /dev/watchdog can only be opened once */
137 	if (test_and_set_bit(0, &wdt->state))
138 		return -EBUSY;
139 
140 	wdt->state |= TWL4030_WDT_STATE_ACTIVE;
141 	file->private_data = (void *) wdt;
142 
143 	twl4030_wdt_enable(wdt);
144 	return nonseekable_open(inode, file);
145 }
146 
147 static int twl4030_wdt_release(struct inode *inode, struct file *file)
148 {
149 	struct twl4030_wdt *wdt = file->private_data;
150 	if (nowayout) {
151 		dev_alert(wdt->miscdev.parent,
152 		       "Unexpected close, watchdog still running!\n");
153 		twl4030_wdt_enable(wdt);
154 	} else {
155 		if (twl4030_wdt_disable(wdt))
156 			return -EFAULT;
157 		wdt->state &= ~TWL4030_WDT_STATE_ACTIVE;
158 	}
159 
160 	clear_bit(0, &wdt->state);
161 	return 0;
162 }
163 
164 static const struct file_operations twl4030_wdt_fops = {
165 	.owner		= THIS_MODULE,
166 	.llseek		= no_llseek,
167 	.open		= twl4030_wdt_open,
168 	.release	= twl4030_wdt_release,
169 	.unlocked_ioctl	= twl4030_wdt_ioctl,
170 	.write		= twl4030_wdt_write_fop,
171 };
172 
173 static int twl4030_wdt_probe(struct platform_device *pdev)
174 {
175 	int ret = 0;
176 	struct twl4030_wdt *wdt;
177 
178 	wdt = kzalloc(sizeof(struct twl4030_wdt), GFP_KERNEL);
179 	if (!wdt)
180 		return -ENOMEM;
181 
182 	wdt->state		= 0;
183 	wdt->timer_margin	= 30;
184 	wdt->miscdev.parent	= &pdev->dev;
185 	wdt->miscdev.fops	= &twl4030_wdt_fops;
186 	wdt->miscdev.minor	= WATCHDOG_MINOR;
187 	wdt->miscdev.name	= "watchdog";
188 
189 	platform_set_drvdata(pdev, wdt);
190 
191 	twl4030_wdt_dev = pdev;
192 
193 	twl4030_wdt_disable(wdt);
194 
195 	ret = misc_register(&wdt->miscdev);
196 	if (ret) {
197 		dev_err(wdt->miscdev.parent,
198 			"Failed to register misc device\n");
199 		platform_set_drvdata(pdev, NULL);
200 		kfree(wdt);
201 		twl4030_wdt_dev = NULL;
202 		return ret;
203 	}
204 	return 0;
205 }
206 
207 static int twl4030_wdt_remove(struct platform_device *pdev)
208 {
209 	struct twl4030_wdt *wdt = platform_get_drvdata(pdev);
210 
211 	if (wdt->state & TWL4030_WDT_STATE_ACTIVE)
212 		if (twl4030_wdt_disable(wdt))
213 			return -EFAULT;
214 
215 	wdt->state &= ~TWL4030_WDT_STATE_ACTIVE;
216 	misc_deregister(&wdt->miscdev);
217 
218 	platform_set_drvdata(pdev, NULL);
219 	kfree(wdt);
220 	twl4030_wdt_dev = NULL;
221 
222 	return 0;
223 }
224 
225 #ifdef CONFIG_PM
226 static int twl4030_wdt_suspend(struct platform_device *pdev, pm_message_t state)
227 {
228 	struct twl4030_wdt *wdt = platform_get_drvdata(pdev);
229 	if (wdt->state & TWL4030_WDT_STATE_ACTIVE)
230 		return twl4030_wdt_disable(wdt);
231 
232 	return 0;
233 }
234 
235 static int twl4030_wdt_resume(struct platform_device *pdev)
236 {
237 	struct twl4030_wdt *wdt = platform_get_drvdata(pdev);
238 	if (wdt->state & TWL4030_WDT_STATE_ACTIVE)
239 		return twl4030_wdt_enable(wdt);
240 
241 	return 0;
242 }
243 #else
244 #define twl4030_wdt_suspend        NULL
245 #define twl4030_wdt_resume         NULL
246 #endif
247 
248 static struct platform_driver twl4030_wdt_driver = {
249 	.probe		= twl4030_wdt_probe,
250 	.remove		= twl4030_wdt_remove,
251 	.suspend	= twl4030_wdt_suspend,
252 	.resume		= twl4030_wdt_resume,
253 	.driver		= {
254 		.owner	= THIS_MODULE,
255 		.name	= "twl4030_wdt",
256 	},
257 };
258 
259 module_platform_driver(twl4030_wdt_driver);
260 
261 MODULE_AUTHOR("Nokia Corporation");
262 MODULE_LICENSE("GPL");
263 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
264 MODULE_ALIAS("platform:twl4030_wdt");
265 
266