1/*
  2 * drivers/char/watchdog/ixp2000_wdt.c
  3 *
  4 * Watchdog driver for Intel IXP2000 network processors
  5 *
  6 * Adapted from the IXP4xx watchdog driver by Lennert Buytenhek.
  7 * The original version carries these notices:
  8 *
  9 * Author: Deepak Saxena <dsaxena@plexity.net>
 10 *
 11 * Copyright 2004 (c) MontaVista, Software, Inc.
 12 * Based on sa1100 driver, Copyright (C) 2000 Oleg Drokin <green@crimea.edu>
 13 *
 14 * This file is licensed under  the terms of the GNU General Public
 15 * License version 2. This program is licensed "as is" without any
 16 * warranty of any kind, whether express or implied.
 17 */
 18
 19#include <linux/module.h>
 20#include <linux/moduleparam.h>
 21#include <linux/types.h>
 22#include <linux/timer.h>
 23#include <linux/kernel.h>
 24#include <linux/fs.h>
 25#include <linux/miscdevice.h>
 26#include <linux/watchdog.h>
 27#include <linux/init.h>
 28#include <linux/bitops.h>
 29#include <linux/uaccess.h>
 30#include <mach/hardware.h>
 31
 32static int nowayout = WATCHDOG_NOWAYOUT;
 33static unsigned int heartbeat = 60;	/* (secs) Default is 1 minute */
 34static unsigned long wdt_status;
 35static spinlock_t wdt_lock;
 36
 37#define	WDT_IN_USE		0
 38#define	WDT_OK_TO_CLOSE		1
 39
 40static unsigned long wdt_tick_rate;
 41
 42static void wdt_enable(void)
 43{
 44	spin_lock(&wdt_lock);
 45	ixp2000_reg_write(IXP2000_RESET0, *(IXP2000_RESET0) | WDT_RESET_ENABLE);
 46	ixp2000_reg_write(IXP2000_TWDE, WDT_ENABLE);
 47	ixp2000_reg_write(IXP2000_T4_CLD, heartbeat * wdt_tick_rate);
 48	ixp2000_reg_write(IXP2000_T4_CTL, TIMER_DIVIDER_256 | TIMER_ENABLE);
 49	spin_unlock(&wdt_lock);
 50}
 51
 52static void wdt_disable(void)
 53{
 54	spin_lock(&wdt_lock);
 55	ixp2000_reg_write(IXP2000_T4_CTL, 0);
 56	spin_unlock(&wdt_lock);
 57}
 58
 59static void wdt_keepalive(void)
 60{
 61	spin_lock(&wdt_lock);
 62	ixp2000_reg_write(IXP2000_T4_CLD, heartbeat * wdt_tick_rate);
 63	spin_unlock(&wdt_lock);
 64}
 65
 66static int ixp2000_wdt_open(struct inode *inode, struct file *file)
 67{
 68	if (test_and_set_bit(WDT_IN_USE, &wdt_status))
 69		return -EBUSY;
 70
 71	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 72
 73	wdt_enable();
 74
 75	return nonseekable_open(inode, file);
 76}
 77
 78static ssize_t ixp2000_wdt_write(struct file *file, const char *data,
 79						size_t len, loff_t *ppos)
 80{
 81	if (len) {
 82		if (!nowayout) {
 83			size_t i;
 84
 85			clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 86
 87			for (i = 0; i != len; i++) {
 88				char c;
 89
 90				if (get_user(c, data + i))
 91					return -EFAULT;
 92				if (c == 'V')
 93					set_bit(WDT_OK_TO_CLOSE, &wdt_status);
 94			}
 95		}
 96		wdt_keepalive();
 97	}
 98
 99	return len;
100}
101
102
103static const struct watchdog_info ident = {
104	.options	= WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT |
105				WDIOF_KEEPALIVEPING,
106	.identity	= "IXP2000 Watchdog",
107};
108
109static long ixp2000_wdt_ioctl(struct file *file, unsigned int cmd,
110							unsigned long arg)
111{
112	int ret = -ENOTTY;
113	int time;
114
115	switch (cmd) {
116	case WDIOC_GETSUPPORT:
117		ret = copy_to_user((struct watchdog_info *)arg, &ident,
118				   sizeof(ident)) ? -EFAULT : 0;
119		break;
120
121	case WDIOC_GETSTATUS:
122		ret = put_user(0, (int *)arg);
123		break;
124
125	case WDIOC_GETBOOTSTATUS:
126		ret = put_user(0, (int *)arg);
127		break;
128
129	case WDIOC_KEEPALIVE:
130		wdt_enable();
131		ret = 0;
132		break;
133
134	case WDIOC_SETTIMEOUT:
135		ret = get_user(time, (int *)arg);
136		if (ret)
137			break;
138
139		if (time <= 0 || time > 60) {
140			ret = -EINVAL;
141			break;
142		}
143
144		heartbeat = time;
145		wdt_keepalive();
146		/* Fall through */
147
148	case WDIOC_GETTIMEOUT:
149		ret = put_user(heartbeat, (int *)arg);
150		break;
151	}
152
153	return ret;
154}
155
156static int ixp2000_wdt_release(struct inode *inode, struct file *file)
157{
158	if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
159		wdt_disable();
160	else
161		printk(KERN_CRIT "WATCHDOG: Device closed unexpectedly - "
162					"timer will not stop\n");
163	clear_bit(WDT_IN_USE, &wdt_status);
164	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
165
166	return 0;
167}
168
169
170static const struct file_operations ixp2000_wdt_fops = {
171	.owner		= THIS_MODULE,
172	.llseek		= no_llseek,
173	.write		= ixp2000_wdt_write,
174	.unlocked_ioctl	= ixp2000_wdt_ioctl,
175	.open		= ixp2000_wdt_open,
176	.release	= ixp2000_wdt_release,
177};
178
179static struct miscdevice ixp2000_wdt_miscdev = {
180	.minor		= WATCHDOG_MINOR,
181	.name		= "watchdog",
182	.fops		= &ixp2000_wdt_fops,
183};
184
185static int __init ixp2000_wdt_init(void)
186{
187	if ((*IXP2000_PRODUCT_ID & 0x001ffef0) == 0x00000000) {
188		printk(KERN_INFO "Unable to use IXP2000 watchdog due to IXP2800 erratum #25.\n");
189		return -EIO;
190	}
191	wdt_tick_rate = (*IXP2000_T1_CLD * HZ) / 256;
192	spin_lock_init(&wdt_lock);
193	return misc_register(&ixp2000_wdt_miscdev);
194}
195
196static void __exit ixp2000_wdt_exit(void)
197{
198	misc_deregister(&ixp2000_wdt_miscdev);
199}
200
201module_init(ixp2000_wdt_init);
202module_exit(ixp2000_wdt_exit);
203
204MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>");
205MODULE_DESCRIPTION("IXP2000 Network Processor Watchdog");
206
207module_param(heartbeat, int, 0);
208MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default 60s)");
209
210module_param(nowayout, int, 0);
211MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
212
213MODULE_LICENSE("GPL");
214MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
215