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