xref: /openbmc/linux/drivers/watchdog/txx9wdt.c (revision 4800cd83)
1 /*
2  * txx9wdt: A Hardware Watchdog Driver for TXx9 SoCs
3  *
4  * Copyright (C) 2007 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
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 version 2 as
8  * 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/miscdevice.h>
14 #include <linux/watchdog.h>
15 #include <linux/fs.h>
16 #include <linux/init.h>
17 #include <linux/uaccess.h>
18 #include <linux/platform_device.h>
19 #include <linux/clk.h>
20 #include <linux/err.h>
21 #include <linux/io.h>
22 #include <asm/txx9tmr.h>
23 
24 #define TIMER_MARGIN	60		/* Default is 60 seconds */
25 
26 static int timeout = TIMER_MARGIN;	/* in seconds */
27 module_param(timeout, int, 0);
28 MODULE_PARM_DESC(timeout,
29 	"Watchdog timeout in seconds. "
30 	"(0<timeout<((2^" __MODULE_STRING(TXX9_TIMER_BITS) ")/(IMCLK/256)), "
31 	"default=" __MODULE_STRING(TIMER_MARGIN) ")");
32 
33 static int nowayout = WATCHDOG_NOWAYOUT;
34 module_param(nowayout, int, 0);
35 MODULE_PARM_DESC(nowayout,
36 	"Watchdog cannot be stopped once started "
37 	"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
38 
39 #define WD_TIMER_CCD	7	/* 1/256 */
40 #define WD_TIMER_CLK	(clk_get_rate(txx9_imclk) / (2 << WD_TIMER_CCD))
41 #define WD_MAX_TIMEOUT	((0xffffffff >> (32 - TXX9_TIMER_BITS)) / WD_TIMER_CLK)
42 
43 static unsigned long txx9wdt_alive;
44 static int expect_close;
45 static struct txx9_tmr_reg __iomem *txx9wdt_reg;
46 static struct clk *txx9_imclk;
47 static DEFINE_SPINLOCK(txx9_lock);
48 
49 static void txx9wdt_ping(void)
50 {
51 	spin_lock(&txx9_lock);
52 	__raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr);
53 	spin_unlock(&txx9_lock);
54 }
55 
56 static void txx9wdt_start(void)
57 {
58 	spin_lock(&txx9_lock);
59 	__raw_writel(WD_TIMER_CLK * timeout, &txx9wdt_reg->cpra);
60 	__raw_writel(WD_TIMER_CCD, &txx9wdt_reg->ccdr);
61 	__raw_writel(0, &txx9wdt_reg->tisr);	/* clear pending interrupt */
62 	__raw_writel(TXx9_TMTCR_TCE | TXx9_TMTCR_CCDE | TXx9_TMTCR_TMODE_WDOG,
63 		     &txx9wdt_reg->tcr);
64 	__raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr);
65 	spin_unlock(&txx9_lock);
66 }
67 
68 static void txx9wdt_stop(void)
69 {
70 	spin_lock(&txx9_lock);
71 	__raw_writel(TXx9_TMWTMR_WDIS, &txx9wdt_reg->wtmr);
72 	__raw_writel(__raw_readl(&txx9wdt_reg->tcr) & ~TXx9_TMTCR_TCE,
73 		     &txx9wdt_reg->tcr);
74 	spin_unlock(&txx9_lock);
75 }
76 
77 static int txx9wdt_open(struct inode *inode, struct file *file)
78 {
79 	if (test_and_set_bit(0, &txx9wdt_alive))
80 		return -EBUSY;
81 
82 	if (__raw_readl(&txx9wdt_reg->tcr) & TXx9_TMTCR_TCE) {
83 		clear_bit(0, &txx9wdt_alive);
84 		return -EBUSY;
85 	}
86 
87 	if (nowayout)
88 		__module_get(THIS_MODULE);
89 
90 	txx9wdt_start();
91 	return nonseekable_open(inode, file);
92 }
93 
94 static int txx9wdt_release(struct inode *inode, struct file *file)
95 {
96 	if (expect_close)
97 		txx9wdt_stop();
98 	else {
99 		printk(KERN_CRIT "txx9wdt: "
100 		       "Unexpected close, not stopping watchdog!\n");
101 		txx9wdt_ping();
102 	}
103 	clear_bit(0, &txx9wdt_alive);
104 	expect_close = 0;
105 	return 0;
106 }
107 
108 static ssize_t txx9wdt_write(struct file *file, const char __user *data,
109 			     size_t len, loff_t *ppos)
110 {
111 	if (len) {
112 		if (!nowayout) {
113 			size_t i;
114 
115 			expect_close = 0;
116 			for (i = 0; i != len; i++) {
117 				char c;
118 				if (get_user(c, data + i))
119 					return -EFAULT;
120 				if (c == 'V')
121 					expect_close = 1;
122 			}
123 		}
124 		txx9wdt_ping();
125 	}
126 	return len;
127 }
128 
129 static long txx9wdt_ioctl(struct file *file, unsigned int cmd,
130 							unsigned long arg)
131 {
132 	void __user *argp = (void __user *)arg;
133 	int __user *p = argp;
134 	int new_timeout;
135 	static const struct watchdog_info ident = {
136 		.options =		WDIOF_SETTIMEOUT |
137 					WDIOF_KEEPALIVEPING |
138 					WDIOF_MAGICCLOSE,
139 		.firmware_version =	0,
140 		.identity =		"Hardware Watchdog for TXx9",
141 	};
142 
143 	switch (cmd) {
144 	case WDIOC_GETSUPPORT:
145 		return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
146 	case WDIOC_GETSTATUS:
147 	case WDIOC_GETBOOTSTATUS:
148 		return put_user(0, p);
149 	case WDIOC_KEEPALIVE:
150 		txx9wdt_ping();
151 		return 0;
152 	case WDIOC_SETTIMEOUT:
153 		if (get_user(new_timeout, p))
154 			return -EFAULT;
155 		if (new_timeout < 1 || new_timeout > WD_MAX_TIMEOUT)
156 			return -EINVAL;
157 		timeout = new_timeout;
158 		txx9wdt_stop();
159 		txx9wdt_start();
160 		/* Fall */
161 	case WDIOC_GETTIMEOUT:
162 		return put_user(timeout, p);
163 	default:
164 		return -ENOTTY;
165 	}
166 }
167 
168 static const struct file_operations txx9wdt_fops = {
169 	.owner		=	THIS_MODULE,
170 	.llseek		=	no_llseek,
171 	.write		=	txx9wdt_write,
172 	.unlocked_ioctl =	txx9wdt_ioctl,
173 	.open		=	txx9wdt_open,
174 	.release	=	txx9wdt_release,
175 };
176 
177 static struct miscdevice txx9wdt_miscdev = {
178 	.minor	=	WATCHDOG_MINOR,
179 	.name	=	"watchdog",
180 	.fops	=	&txx9wdt_fops,
181 };
182 
183 static int __init txx9wdt_probe(struct platform_device *dev)
184 {
185 	struct resource *res;
186 	int ret;
187 
188 	txx9_imclk = clk_get(NULL, "imbus_clk");
189 	if (IS_ERR(txx9_imclk)) {
190 		ret = PTR_ERR(txx9_imclk);
191 		txx9_imclk = NULL;
192 		goto exit;
193 	}
194 	ret = clk_enable(txx9_imclk);
195 	if (ret) {
196 		clk_put(txx9_imclk);
197 		txx9_imclk = NULL;
198 		goto exit;
199 	}
200 
201 	res = platform_get_resource(dev, IORESOURCE_MEM, 0);
202 	if (!res)
203 		goto exit_busy;
204 	if (!devm_request_mem_region(&dev->dev, res->start, resource_size(res),
205 				     "txx9wdt"))
206 		goto exit_busy;
207 	txx9wdt_reg = devm_ioremap(&dev->dev, res->start, resource_size(res));
208 	if (!txx9wdt_reg)
209 		goto exit_busy;
210 
211 	ret = misc_register(&txx9wdt_miscdev);
212 	if (ret) {
213 		goto exit;
214 	}
215 
216 	printk(KERN_INFO "Hardware Watchdog Timer for TXx9: "
217 	       "timeout=%d sec (max %ld) (nowayout= %d)\n",
218 	       timeout, WD_MAX_TIMEOUT, nowayout);
219 
220 	return 0;
221 exit_busy:
222 	ret = -EBUSY;
223 exit:
224 	if (txx9_imclk) {
225 		clk_disable(txx9_imclk);
226 		clk_put(txx9_imclk);
227 	}
228 	return ret;
229 }
230 
231 static int __exit txx9wdt_remove(struct platform_device *dev)
232 {
233 	misc_deregister(&txx9wdt_miscdev);
234 	clk_disable(txx9_imclk);
235 	clk_put(txx9_imclk);
236 	return 0;
237 }
238 
239 static void txx9wdt_shutdown(struct platform_device *dev)
240 {
241 	txx9wdt_stop();
242 }
243 
244 static struct platform_driver txx9wdt_driver = {
245 	.remove = __exit_p(txx9wdt_remove),
246 	.shutdown = txx9wdt_shutdown,
247 	.driver = {
248 		.name = "txx9wdt",
249 		.owner = THIS_MODULE,
250 	},
251 };
252 
253 static int __init watchdog_init(void)
254 {
255 	return platform_driver_probe(&txx9wdt_driver, txx9wdt_probe);
256 }
257 
258 static void __exit watchdog_exit(void)
259 {
260 	platform_driver_unregister(&txx9wdt_driver);
261 }
262 
263 module_init(watchdog_init);
264 module_exit(watchdog_exit);
265 
266 MODULE_DESCRIPTION("TXx9 Watchdog Driver");
267 MODULE_LICENSE("GPL");
268 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
269 MODULE_ALIAS("platform:txx9wdt");
270