1/*
2 * mpc83xx_wdt.c - MPC83xx 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 *
9 * Note: it appears that you can only actually ENABLE or DISABLE the thing
10 * once after POR. Once enabled, you cannot disable, and vice versa.
11 *
12 * This program is free software; you can redistribute  it and/or modify it
13 * under  the terms of  the GNU General  Public License as published by the
14 * Free Software Foundation;  either version 2 of the  License, or (at your
15 * option) any later version.
16 */
17
18#include <linux/fs.h>
19#include <linux/init.h>
20#include <linux/kernel.h>
21#include <linux/miscdevice.h>
22#include <linux/platform_device.h>
23#include <linux/module.h>
24#include <linux/watchdog.h>
25#include <asm/io.h>
26#include <asm/uaccess.h>
27
28struct mpc83xx_wdt {
29	__be32 res0;
30	__be32 swcrr; /* System watchdog control register */
31#define SWCRR_SWTC 0xFFFF0000 /* Software Watchdog Time Count. */
32#define SWCRR_SWEN 0x00000004 /* Watchdog Enable bit. */
33#define SWCRR_SWRI 0x00000002 /* Software Watchdog Reset/Interrupt Select bit.*/
34#define SWCRR_SWPR 0x00000001 /* Software Watchdog Counter Prescale bit. */
35	__be32 swcnr; /* System watchdog count register */
36	u8 res1[2];
37	__be16 swsrr; /* System watchdog service register */
38	u8 res2[0xF0];
39};
40
41static struct mpc83xx_wdt __iomem *wd_base;
42
43static u16 timeout = 0xffff;
44module_param(timeout, ushort, 0);
45MODULE_PARM_DESC(timeout, "Watchdog timeout in ticks. (0<timeout<65536, default=65535");
46
47static int reset = 1;
48module_param(reset, bool, 0);
49MODULE_PARM_DESC(reset, "Watchdog Interrupt/Reset Mode. 0 = interrupt, 1 = reset");
50
51/*
52 * We always prescale, but if someone really doesn't want to they can set this
53 * to 0
54 */
55static int prescale = 1;
56static unsigned int timeout_sec;
57
58static unsigned long wdt_is_open;
59static spinlock_t wdt_spinlock;
60
61static void mpc83xx_wdt_keepalive(void)
62{
63	/* Ping the WDT */
64	spin_lock(&wdt_spinlock);
65	out_be16(&wd_base->swsrr, 0x556c);
66	out_be16(&wd_base->swsrr, 0xaa39);
67	spin_unlock(&wdt_spinlock);
68}
69
70static ssize_t mpc83xx_wdt_write(struct file *file, const char __user *buf,
71				 size_t count, loff_t *ppos)
72{
73	if (count)
74		mpc83xx_wdt_keepalive();
75	return count;
76}
77
78static int mpc83xx_wdt_open(struct inode *inode, struct file *file)
79{
80	u32 tmp = SWCRR_SWEN;
81	if (test_and_set_bit(0, &wdt_is_open))
82		return -EBUSY;
83
84	/* Once we start the watchdog we can't stop it */
85	__module_get(THIS_MODULE);
86
87	/* Good, fire up the show */
88	if (prescale)
89		tmp |= SWCRR_SWPR;
90	if (reset)
91		tmp |= SWCRR_SWRI;
92
93	tmp |= timeout << 16;
94
95	out_be32(&wd_base->swcrr, tmp);
96
97	return nonseekable_open(inode, file);
98}
99
100static int mpc83xx_wdt_release(struct inode *inode, struct file *file)
101{
102	printk(KERN_CRIT "Unexpected close, not stopping watchdog!\n");
103	mpc83xx_wdt_keepalive();
104	clear_bit(0, &wdt_is_open);
105	return 0;
106}
107
108static int mpc83xx_wdt_ioctl(struct inode *inode, struct file *file,
109				unsigned int cmd, unsigned long arg)
110{
111	void __user *argp = (void __user *)arg;
112	int __user *p = argp;
113	static struct watchdog_info ident = {
114		.options = WDIOF_KEEPALIVEPING,
115		.firmware_version = 1,
116		.identity = "MPC83xx",
117	};
118
119	switch (cmd) {
120	case WDIOC_GETSUPPORT:
121		return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
122	case WDIOC_KEEPALIVE:
123		mpc83xx_wdt_keepalive();
124		return 0;
125	case WDIOC_GETTIMEOUT:
126		return put_user(timeout_sec, p);
127	default:
128		return -ENOTTY;
129	}
130}
131
132static const struct file_operations mpc83xx_wdt_fops = {
133	.owner		= THIS_MODULE,
134	.llseek		= no_llseek,
135	.write		= mpc83xx_wdt_write,
136	.ioctl		= mpc83xx_wdt_ioctl,
137	.open		= mpc83xx_wdt_open,
138	.release	= mpc83xx_wdt_release,
139};
140
141static struct miscdevice mpc83xx_wdt_miscdev = {
142	.minor	= WATCHDOG_MINOR,
143	.name	= "watchdog",
144	.fops	= &mpc83xx_wdt_fops,
145};
146
147static int __devinit mpc83xx_wdt_probe(struct platform_device *dev)
148{
149	struct resource *r;
150	int ret;
151	unsigned int *freq = dev->dev.platform_data;
152
153	/* get a pointer to the register memory */
154	r = platform_get_resource(dev, IORESOURCE_MEM, 0);
155
156	if (!r) {
157		ret = -ENODEV;
158		goto err_out;
159	}
160
161	wd_base = ioremap(r->start, sizeof (struct mpc83xx_wdt));
162
163	if (wd_base == NULL) {
164		ret = -ENOMEM;
165		goto err_out;
166	}
167
168	ret = misc_register(&mpc83xx_wdt_miscdev);
169	if (ret) {
170		printk(KERN_ERR "cannot register miscdev on minor=%d "
171				"(err=%d)\n",
172				WATCHDOG_MINOR, ret);
173		goto err_unmap;
174	}
175
176	/* Calculate the timeout in seconds */
177	if (prescale)
178		timeout_sec = (timeout * 0x10000) / (*freq);
179	else
180		timeout_sec = timeout / (*freq);
181
182	printk(KERN_INFO "WDT driver for MPC83xx initialized. "
183		"mode:%s timeout=%d (%d seconds)\n",
184		reset ? "reset":"interrupt", timeout, timeout_sec);
185
186	spin_lock_init(&wdt_spinlock);
187
188	return 0;
189
190err_unmap:
191	iounmap(wd_base);
192err_out:
193	return ret;
194}
195
196static int __devexit mpc83xx_wdt_remove(struct platform_device *dev)
197{
198	misc_deregister(&mpc83xx_wdt_miscdev);
199	iounmap(wd_base);
200
201	return 0;
202}
203
204static struct platform_driver mpc83xx_wdt_driver = {
205	.probe		= mpc83xx_wdt_probe,
206	.remove		= __devexit_p(mpc83xx_wdt_remove),
207	.driver		= {
208		.name	= "mpc83xx_wdt",
209	},
210};
211
212static int __init mpc83xx_wdt_init(void)
213{
214	return platform_driver_register(&mpc83xx_wdt_driver);
215}
216
217static void __exit mpc83xx_wdt_exit(void)
218{
219	platform_driver_unregister(&mpc83xx_wdt_driver);
220}
221
222module_init(mpc83xx_wdt_init);
223module_exit(mpc83xx_wdt_exit);
224
225MODULE_AUTHOR("Dave Updegraff, Kumar Gala");
226MODULE_DESCRIPTION("Driver for watchdog timer in MPC83xx uProcessor");
227MODULE_LICENSE("GPL");
228MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
229