1/*
2 * drivers/char/watchdog/iop_wdt.c
3 *
4 * WDT driver for Intel I/O Processors
5 * Copyright (C) 2005, Intel Corporation.
6 *
7 * Based on ixp4xx driver, Copyright 2004 (c) MontaVista, Software, Inc.
8 *
9 * This program is free software; you can redistribute it and/or modify it
10 * under the terms and conditions of the GNU General Public License,
11 * version 2, as published by the Free Software Foundation.
12 *
13 * This program is distributed in the hope it will be useful, but WITHOUT
14 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
16 * more details.
17 *
18 * You should have received a copy of the GNU General Public License along with
19 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
20 * Place - Suite 330, Boston, MA 02111-1307 USA.
21 *
22 *	Curt E Bruns <curt.e.bruns@intel.com>
23 *	Peter Milne <peter.milne@d-tacq.com>
24 *	Dan Williams <dan.j.williams@intel.com>
25 */
26
27#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
28
29#include <linux/module.h>
30#include <linux/kernel.h>
31#include <linux/fs.h>
32#include <linux/init.h>
33#include <linux/device.h>
34#include <linux/miscdevice.h>
35#include <linux/watchdog.h>
36#include <linux/uaccess.h>
37#include <mach/hardware.h>
38
39static bool nowayout = WATCHDOG_NOWAYOUT;
40static unsigned long wdt_status;
41static unsigned long boot_status;
42static DEFINE_SPINLOCK(wdt_lock);
43
44#define WDT_IN_USE		0
45#define WDT_OK_TO_CLOSE		1
46#define WDT_ENABLED		2
47
48static unsigned long iop_watchdog_timeout(void)
49{
50	return (0xffffffffUL / get_iop_tick_rate());
51}
52
53/**
54 * wdt_supports_disable - determine if we are accessing a iop13xx watchdog
55 * or iop3xx by whether it has a disable command
56 */
57static int wdt_supports_disable(void)
58{
59	int can_disable;
60
61	if (IOP_WDTCR_EN_ARM != IOP_WDTCR_DIS_ARM)
62		can_disable = 1;
63	else
64		can_disable = 0;
65
66	return can_disable;
67}
68
69static void wdt_enable(void)
70{
71	/* Arm and enable the Timer to starting counting down from 0xFFFF.FFFF
72	 * Takes approx. 10.7s to timeout
73	 */
74	spin_lock(&wdt_lock);
75	write_wdtcr(IOP_WDTCR_EN_ARM);
76	write_wdtcr(IOP_WDTCR_EN);
77	spin_unlock(&wdt_lock);
78}
79
80/* returns 0 if the timer was successfully disabled */
81static int wdt_disable(void)
82{
83	/* Stop Counting */
84	if (wdt_supports_disable()) {
85		spin_lock(&wdt_lock);
86		write_wdtcr(IOP_WDTCR_DIS_ARM);
87		write_wdtcr(IOP_WDTCR_DIS);
88		clear_bit(WDT_ENABLED, &wdt_status);
89		spin_unlock(&wdt_lock);
90		pr_info("Disabled\n");
91		return 0;
92	} else
93		return 1;
94}
95
96static int iop_wdt_open(struct inode *inode, struct file *file)
97{
98	if (test_and_set_bit(WDT_IN_USE, &wdt_status))
99		return -EBUSY;
100
101	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
102	wdt_enable();
103	set_bit(WDT_ENABLED, &wdt_status);
104	return nonseekable_open(inode, file);
105}
106
107static ssize_t iop_wdt_write(struct file *file, const char *data, size_t len,
108		  loff_t *ppos)
109{
110	if (len) {
111		if (!nowayout) {
112			size_t i;
113
114			clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
115
116			for (i = 0; i != len; i++) {
117				char c;
118
119				if (get_user(c, data + i))
120					return -EFAULT;
121				if (c == 'V')
122					set_bit(WDT_OK_TO_CLOSE, &wdt_status);
123			}
124		}
125		wdt_enable();
126	}
127	return len;
128}
129
130static const struct watchdog_info ident = {
131	.options = WDIOF_CARDRESET | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
132	.identity = "iop watchdog",
133};
134
135static long iop_wdt_ioctl(struct file *file,
136				unsigned int cmd, unsigned long arg)
137{
138	int options;
139	int ret = -ENOTTY;
140	int __user *argp = (int __user *)arg;
141
142	switch (cmd) {
143	case WDIOC_GETSUPPORT:
144		if (copy_to_user(argp, &ident, sizeof(ident)))
145			ret = -EFAULT;
146		else
147			ret = 0;
148		break;
149
150	case WDIOC_GETSTATUS:
151		ret = put_user(0, argp);
152		break;
153
154	case WDIOC_GETBOOTSTATUS:
155		ret = put_user(boot_status, argp);
156		break;
157
158	case WDIOC_SETOPTIONS:
159		if (get_user(options, (int *)arg))
160			return -EFAULT;
161
162		if (options & WDIOS_DISABLECARD) {
163			if (!nowayout) {
164				if (wdt_disable() == 0) {
165					set_bit(WDT_OK_TO_CLOSE, &wdt_status);
166					ret = 0;
167				} else
168					ret = -ENXIO;
169			} else
170				ret = 0;
171		}
172		if (options & WDIOS_ENABLECARD) {
173			wdt_enable();
174			ret = 0;
175		}
176		break;
177
178	case WDIOC_KEEPALIVE:
179		wdt_enable();
180		ret = 0;
181		break;
182
183	case WDIOC_GETTIMEOUT:
184		ret = put_user(iop_watchdog_timeout(), argp);
185		break;
186	}
187	return ret;
188}
189
190static int iop_wdt_release(struct inode *inode, struct file *file)
191{
192	int state = 1;
193	if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
194		if (test_bit(WDT_ENABLED, &wdt_status))
195			state = wdt_disable();
196
197	/* if the timer is not disabled reload and notify that we are still
198	 * going down
199	 */
200	if (state != 0) {
201		wdt_enable();
202		pr_crit("Device closed unexpectedly - reset in %lu seconds\n",
203			iop_watchdog_timeout());
204	}
205
206	clear_bit(WDT_IN_USE, &wdt_status);
207	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
208
209	return 0;
210}
211
212static const struct file_operations iop_wdt_fops = {
213	.owner = THIS_MODULE,
214	.llseek = no_llseek,
215	.write = iop_wdt_write,
216	.unlocked_ioctl = iop_wdt_ioctl,
217	.open = iop_wdt_open,
218	.release = iop_wdt_release,
219};
220
221static struct miscdevice iop_wdt_miscdev = {
222	.minor = WATCHDOG_MINOR,
223	.name = "watchdog",
224	.fops = &iop_wdt_fops,
225};
226
227static int __init iop_wdt_init(void)
228{
229	int ret;
230
231	/* check if the reset was caused by the watchdog timer */
232	boot_status = (read_rcsr() & IOP_RCSR_WDT) ? WDIOF_CARDRESET : 0;
233
234	/* Configure Watchdog Timeout to cause an Internal Bus (IB) Reset
235	 * NOTE: An IB Reset will Reset both cores in the IOP342
236	 */
237	write_wdtsr(IOP13XX_WDTCR_IB_RESET);
238
239	/* Register after we have the device set up so we cannot race
240	   with an open */
241	ret = misc_register(&iop_wdt_miscdev);
242	if (ret == 0)
243		pr_info("timeout %lu sec\n", iop_watchdog_timeout());
244
245	return ret;
246}
247
248static void __exit iop_wdt_exit(void)
249{
250	misc_deregister(&iop_wdt_miscdev);
251}
252
253module_init(iop_wdt_init);
254module_exit(iop_wdt_exit);
255
256module_param(nowayout, bool, 0);
257MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
258
259MODULE_AUTHOR("Curt E Bruns <curt.e.bruns@intel.com>");
260MODULE_DESCRIPTION("iop watchdog timer driver");
261MODULE_LICENSE("GPL");
262