1 /*
2  * mpc8xxx_wdt.c - MPC8xx/MPC83xx/MPC86xx watchdog userspace interface
3  *
4  * Authors: Dave Updegraff <dave@cray.org>
5  *	    Kumar Gala <galak@kernel.crashing.org>
6  *		Attribution: from 83xx_wst: Florian Schirmer <jolt@tuxbox.org>
7  *				..and from sc520_wdt
8  * Copyright (c) 2008  MontaVista Software, Inc.
9  *                     Anton Vorontsov <avorontsov@ru.mvista.com>
10  *
11  * Note: it appears that you can only actually ENABLE or DISABLE the thing
12  * once after POR. Once enabled, you cannot disable, and vice versa.
13  *
14  * This program is free software; you can redistribute  it and/or modify it
15  * under  the terms of  the GNU General  Public License as published by the
16  * Free Software Foundation;  either version 2 of the  License, or (at your
17  * option) any later version.
18  */
19 
20 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
21 
22 #include <linux/fs.h>
23 #include <linux/init.h>
24 #include <linux/kernel.h>
25 #include <linux/timer.h>
26 #include <linux/miscdevice.h>
27 #include <linux/of_platform.h>
28 #include <linux/module.h>
29 #include <linux/watchdog.h>
30 #include <linux/io.h>
31 #include <linux/uaccess.h>
32 #include <sysdev/fsl_soc.h>
33 
34 struct mpc8xxx_wdt {
35 	__be32 res0;
36 	__be32 swcrr; /* System watchdog control register */
37 #define SWCRR_SWTC 0xFFFF0000 /* Software Watchdog Time Count. */
38 #define SWCRR_SWEN 0x00000004 /* Watchdog Enable bit. */
39 #define SWCRR_SWRI 0x00000002 /* Software Watchdog Reset/Interrupt Select bit.*/
40 #define SWCRR_SWPR 0x00000001 /* Software Watchdog Counter Prescale bit. */
41 	__be32 swcnr; /* System watchdog count register */
42 	u8 res1[2];
43 	__be16 swsrr; /* System watchdog service register */
44 	u8 res2[0xF0];
45 };
46 
47 struct mpc8xxx_wdt_type {
48 	int prescaler;
49 	bool hw_enabled;
50 };
51 
52 static struct mpc8xxx_wdt __iomem *wd_base;
53 static int mpc8xxx_wdt_init_late(void);
54 
55 static u16 timeout = 0xffff;
56 module_param(timeout, ushort, 0);
57 MODULE_PARM_DESC(timeout,
58 	"Watchdog timeout in ticks. (0<timeout<65536, default=65535)");
59 
60 static bool reset = 1;
61 module_param(reset, bool, 0);
62 MODULE_PARM_DESC(reset,
63 	"Watchdog Interrupt/Reset Mode. 0 = interrupt, 1 = reset");
64 
65 static bool nowayout = WATCHDOG_NOWAYOUT;
66 module_param(nowayout, bool, 0);
67 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
68 		 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
69 
70 /*
71  * We always prescale, but if someone really doesn't want to they can set this
72  * to 0
73  */
74 static int prescale = 1;
75 static unsigned int timeout_sec;
76 
77 static unsigned long wdt_is_open;
78 static DEFINE_SPINLOCK(wdt_spinlock);
79 
80 static void mpc8xxx_wdt_keepalive(void)
81 {
82 	/* Ping the WDT */
83 	spin_lock(&wdt_spinlock);
84 	out_be16(&wd_base->swsrr, 0x556c);
85 	out_be16(&wd_base->swsrr, 0xaa39);
86 	spin_unlock(&wdt_spinlock);
87 }
88 
89 static void mpc8xxx_wdt_timer_ping(unsigned long arg);
90 static DEFINE_TIMER(wdt_timer, mpc8xxx_wdt_timer_ping, 0, 0);
91 
92 static void mpc8xxx_wdt_timer_ping(unsigned long arg)
93 {
94 	mpc8xxx_wdt_keepalive();
95 	/* We're pinging it twice faster than needed, just to be sure. */
96 	mod_timer(&wdt_timer, jiffies + HZ * timeout_sec / 2);
97 }
98 
99 static void mpc8xxx_wdt_pr_warn(const char *msg)
100 {
101 	pr_crit("%s, expect the %s soon!\n", msg,
102 		reset ? "reset" : "machine check exception");
103 }
104 
105 static ssize_t mpc8xxx_wdt_write(struct file *file, const char __user *buf,
106 				 size_t count, loff_t *ppos)
107 {
108 	if (count)
109 		mpc8xxx_wdt_keepalive();
110 	return count;
111 }
112 
113 static int mpc8xxx_wdt_open(struct inode *inode, struct file *file)
114 {
115 	u32 tmp = SWCRR_SWEN;
116 	if (test_and_set_bit(0, &wdt_is_open))
117 		return -EBUSY;
118 
119 	/* Once we start the watchdog we can't stop it */
120 	if (nowayout)
121 		__module_get(THIS_MODULE);
122 
123 	/* Good, fire up the show */
124 	if (prescale)
125 		tmp |= SWCRR_SWPR;
126 	if (reset)
127 		tmp |= SWCRR_SWRI;
128 
129 	tmp |= timeout << 16;
130 
131 	out_be32(&wd_base->swcrr, tmp);
132 
133 	del_timer_sync(&wdt_timer);
134 
135 	return nonseekable_open(inode, file);
136 }
137 
138 static int mpc8xxx_wdt_release(struct inode *inode, struct file *file)
139 {
140 	if (!nowayout)
141 		mpc8xxx_wdt_timer_ping(0);
142 	else
143 		mpc8xxx_wdt_pr_warn("watchdog closed");
144 	clear_bit(0, &wdt_is_open);
145 	return 0;
146 }
147 
148 static long mpc8xxx_wdt_ioctl(struct file *file, unsigned int cmd,
149 							unsigned long arg)
150 {
151 	void __user *argp = (void __user *)arg;
152 	int __user *p = argp;
153 	static const struct watchdog_info ident = {
154 		.options = WDIOF_KEEPALIVEPING,
155 		.firmware_version = 1,
156 		.identity = "MPC8xxx",
157 	};
158 
159 	switch (cmd) {
160 	case WDIOC_GETSUPPORT:
161 		return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
162 	case WDIOC_GETSTATUS:
163 	case WDIOC_GETBOOTSTATUS:
164 		return put_user(0, p);
165 	case WDIOC_KEEPALIVE:
166 		mpc8xxx_wdt_keepalive();
167 		return 0;
168 	case WDIOC_GETTIMEOUT:
169 		return put_user(timeout_sec, p);
170 	default:
171 		return -ENOTTY;
172 	}
173 }
174 
175 static const struct file_operations mpc8xxx_wdt_fops = {
176 	.owner		= THIS_MODULE,
177 	.llseek		= no_llseek,
178 	.write		= mpc8xxx_wdt_write,
179 	.unlocked_ioctl	= mpc8xxx_wdt_ioctl,
180 	.open		= mpc8xxx_wdt_open,
181 	.release	= mpc8xxx_wdt_release,
182 };
183 
184 static struct miscdevice mpc8xxx_wdt_miscdev = {
185 	.minor	= WATCHDOG_MINOR,
186 	.name	= "watchdog",
187 	.fops	= &mpc8xxx_wdt_fops,
188 };
189 
190 static const struct of_device_id mpc8xxx_wdt_match[];
191 static int __devinit mpc8xxx_wdt_probe(struct platform_device *ofdev)
192 {
193 	int ret;
194 	const struct of_device_id *match;
195 	struct device_node *np = ofdev->dev.of_node;
196 	const struct mpc8xxx_wdt_type *wdt_type;
197 	u32 freq = fsl_get_sys_freq();
198 	bool enabled;
199 
200 	match = of_match_device(mpc8xxx_wdt_match, &ofdev->dev);
201 	if (!match)
202 		return -EINVAL;
203 	wdt_type = match->data;
204 
205 	if (!freq || freq == -1)
206 		return -EINVAL;
207 
208 	wd_base = of_iomap(np, 0);
209 	if (!wd_base)
210 		return -ENOMEM;
211 
212 	enabled = in_be32(&wd_base->swcrr) & SWCRR_SWEN;
213 	if (!enabled && wdt_type->hw_enabled) {
214 		pr_info("could not be enabled in software\n");
215 		ret = -ENOSYS;
216 		goto err_unmap;
217 	}
218 
219 	/* Calculate the timeout in seconds */
220 	if (prescale)
221 		timeout_sec = (timeout * wdt_type->prescaler) / freq;
222 	else
223 		timeout_sec = timeout / freq;
224 
225 #ifdef MODULE
226 	ret = mpc8xxx_wdt_init_late();
227 	if (ret)
228 		goto err_unmap;
229 #endif
230 
231 	pr_info("WDT driver for MPC8xxx initialized. mode:%s timeout=%d (%d seconds)\n",
232 		reset ? "reset" : "interrupt", timeout, timeout_sec);
233 
234 	/*
235 	 * If the watchdog was previously enabled or we're running on
236 	 * MPC8xxx, we should ping the wdt from the kernel until the
237 	 * userspace handles it.
238 	 */
239 	if (enabled)
240 		mpc8xxx_wdt_timer_ping(0);
241 	return 0;
242 err_unmap:
243 	iounmap(wd_base);
244 	wd_base = NULL;
245 	return ret;
246 }
247 
248 static int __devexit mpc8xxx_wdt_remove(struct platform_device *ofdev)
249 {
250 	mpc8xxx_wdt_pr_warn("watchdog removed");
251 	del_timer_sync(&wdt_timer);
252 	misc_deregister(&mpc8xxx_wdt_miscdev);
253 	iounmap(wd_base);
254 
255 	return 0;
256 }
257 
258 static const struct of_device_id mpc8xxx_wdt_match[] = {
259 	{
260 		.compatible = "mpc83xx_wdt",
261 		.data = &(struct mpc8xxx_wdt_type) {
262 			.prescaler = 0x10000,
263 		},
264 	},
265 	{
266 		.compatible = "fsl,mpc8610-wdt",
267 		.data = &(struct mpc8xxx_wdt_type) {
268 			.prescaler = 0x10000,
269 			.hw_enabled = true,
270 		},
271 	},
272 	{
273 		.compatible = "fsl,mpc823-wdt",
274 		.data = &(struct mpc8xxx_wdt_type) {
275 			.prescaler = 0x800,
276 		},
277 	},
278 	{},
279 };
280 MODULE_DEVICE_TABLE(of, mpc8xxx_wdt_match);
281 
282 static struct platform_driver mpc8xxx_wdt_driver = {
283 	.probe		= mpc8xxx_wdt_probe,
284 	.remove		= __devexit_p(mpc8xxx_wdt_remove),
285 	.driver = {
286 		.name = "mpc8xxx_wdt",
287 		.owner = THIS_MODULE,
288 		.of_match_table = mpc8xxx_wdt_match,
289 	},
290 };
291 
292 /*
293  * We do wdt initialization in two steps: arch_initcall probes the wdt
294  * very early to start pinging the watchdog (misc devices are not yet
295  * available), and later module_init() just registers the misc device.
296  */
297 static int mpc8xxx_wdt_init_late(void)
298 {
299 	int ret;
300 
301 	if (!wd_base)
302 		return -ENODEV;
303 
304 	ret = misc_register(&mpc8xxx_wdt_miscdev);
305 	if (ret) {
306 		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
307 		       WATCHDOG_MINOR, ret);
308 		return ret;
309 	}
310 	return 0;
311 }
312 #ifndef MODULE
313 module_init(mpc8xxx_wdt_init_late);
314 #endif
315 
316 static int __init mpc8xxx_wdt_init(void)
317 {
318 	return platform_driver_register(&mpc8xxx_wdt_driver);
319 }
320 arch_initcall(mpc8xxx_wdt_init);
321 
322 static void __exit mpc8xxx_wdt_exit(void)
323 {
324 	platform_driver_unregister(&mpc8xxx_wdt_driver);
325 }
326 module_exit(mpc8xxx_wdt_exit);
327 
328 MODULE_AUTHOR("Dave Updegraff, Kumar Gala");
329 MODULE_DESCRIPTION("Driver for watchdog timer in MPC8xx/MPC83xx/MPC86xx "
330 		   "uProcessors");
331 MODULE_LICENSE("GPL");
332 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
333