1/*
2 *  PNX833x Hardware Watchdog Driver
3 *  Copyright 2008 NXP Semiconductors
4 *  Daniel Laird <daniel.j.laird@nxp.com>
5 *  Andre McCurdy <andre.mccurdy@nxp.com>
6 *
7 *  Heavily based upon - IndyDog	0.3
8 *  A Hardware Watchdog Device for SGI IP22
9 *
10 * (c) Copyright 2002 Guido Guenther <agx@sigxcpu.org>, All Rights Reserved.
11 *
12 * This program is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU General Public License
14 * as published by the Free Software Foundation; either version
15 * 2 of the License, or (at your option) any later version.
16 *
17 * based on softdog.c by Alan Cox <alan@redhat.com>
18 */
19
20#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
21
22#include <linux/module.h>
23#include <linux/moduleparam.h>
24#include <linux/types.h>
25#include <linux/kernel.h>
26#include <linux/fs.h>
27#include <linux/mm.h>
28#include <linux/miscdevice.h>
29#include <linux/watchdog.h>
30#include <linux/notifier.h>
31#include <linux/reboot.h>
32#include <linux/init.h>
33#include <asm/mach-pnx833x/pnx833x.h>
34
35#define WATCHDOG_TIMEOUT 30		/* 30 sec Maximum timeout */
36#define WATCHDOG_COUNT_FREQUENCY 68000000U /* Watchdog counts at 68MHZ. */
37#define	PNX_WATCHDOG_TIMEOUT	(WATCHDOG_TIMEOUT * WATCHDOG_COUNT_FREQUENCY)
38#define PNX_TIMEOUT_VALUE	2040000000U
39
40/** CONFIG block */
41#define PNX833X_CONFIG                      (0x07000U)
42#define PNX833X_CONFIG_CPU_WATCHDOG         (0x54)
43#define PNX833X_CONFIG_CPU_WATCHDOG_COMPARE (0x58)
44#define PNX833X_CONFIG_CPU_COUNTERS_CONTROL (0x1c)
45
46/** RESET block */
47#define PNX833X_RESET                       (0x08000U)
48#define PNX833X_RESET_CONFIG                (0x08)
49
50static int pnx833x_wdt_alive;
51
52/* Set default timeout in MHZ.*/
53static int pnx833x_wdt_timeout = PNX_WATCHDOG_TIMEOUT;
54module_param(pnx833x_wdt_timeout, int, 0);
55MODULE_PARM_DESC(timeout, "Watchdog timeout in Mhz. (68Mhz clock), default="
56			__MODULE_STRING(PNX_TIMEOUT_VALUE) "(30 seconds).");
57
58static bool nowayout = WATCHDOG_NOWAYOUT;
59module_param(nowayout, bool, 0);
60MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
61					__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
62
63#define START_DEFAULT	1
64static int start_enabled = START_DEFAULT;
65module_param(start_enabled, int, 0);
66MODULE_PARM_DESC(start_enabled, "Watchdog is started on module insertion "
67				"(default=" __MODULE_STRING(START_DEFAULT) ")");
68
69static void pnx833x_wdt_start(void)
70{
71	/* Enable watchdog causing reset. */
72	PNX833X_REG(PNX833X_RESET + PNX833X_RESET_CONFIG) |= 0x1;
73	/* Set timeout.*/
74	PNX833X_REG(PNX833X_CONFIG +
75		PNX833X_CONFIG_CPU_WATCHDOG_COMPARE) = pnx833x_wdt_timeout;
76	/* Enable watchdog. */
77	PNX833X_REG(PNX833X_CONFIG +
78				PNX833X_CONFIG_CPU_COUNTERS_CONTROL) |= 0x1;
79
80	pr_info("Started watchdog timer\n");
81}
82
83static void pnx833x_wdt_stop(void)
84{
85	/* Disable watchdog causing reset. */
86	PNX833X_REG(PNX833X_RESET + PNX833X_CONFIG) &= 0xFFFFFFFE;
87	/* Disable watchdog.*/
88	PNX833X_REG(PNX833X_CONFIG +
89			PNX833X_CONFIG_CPU_COUNTERS_CONTROL) &= 0xFFFFFFFE;
90
91	pr_info("Stopped watchdog timer\n");
92}
93
94static void pnx833x_wdt_ping(void)
95{
96	PNX833X_REG(PNX833X_CONFIG +
97		PNX833X_CONFIG_CPU_WATCHDOG_COMPARE) = pnx833x_wdt_timeout;
98}
99
100/*
101 *	Allow only one person to hold it open
102 */
103static int pnx833x_wdt_open(struct inode *inode, struct file *file)
104{
105	if (test_and_set_bit(0, &pnx833x_wdt_alive))
106		return -EBUSY;
107
108	if (nowayout)
109		__module_get(THIS_MODULE);
110
111	/* Activate timer */
112	if (!start_enabled)
113		pnx833x_wdt_start();
114
115	pnx833x_wdt_ping();
116
117	pr_info("Started watchdog timer\n");
118
119	return nonseekable_open(inode, file);
120}
121
122static int pnx833x_wdt_release(struct inode *inode, struct file *file)
123{
124	/* Shut off the timer.
125	 * Lock it in if it's a module and we defined ...NOWAYOUT */
126	if (!nowayout)
127		pnx833x_wdt_stop(); /* Turn the WDT off */
128
129	clear_bit(0, &pnx833x_wdt_alive);
130	return 0;
131}
132
133static ssize_t pnx833x_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
134{
135	/* Refresh the timer. */
136	if (len)
137		pnx833x_wdt_ping();
138
139	return len;
140}
141
142static long pnx833x_wdt_ioctl(struct file *file, unsigned int cmd,
143							unsigned long arg)
144{
145	int options, new_timeout = 0;
146	uint32_t timeout, timeout_left = 0;
147
148	static const struct watchdog_info ident = {
149		.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
150		.firmware_version = 0,
151		.identity = "Hardware Watchdog for PNX833x",
152	};
153
154	switch (cmd) {
155	default:
156		return -ENOTTY;
157
158	case WDIOC_GETSUPPORT:
159		if (copy_to_user((struct watchdog_info *)arg,
160				 &ident, sizeof(ident)))
161			return -EFAULT;
162		return 0;
163
164	case WDIOC_GETSTATUS:
165	case WDIOC_GETBOOTSTATUS:
166		return put_user(0, (int *)arg);
167
168	case WDIOC_SETOPTIONS:
169		if (get_user(options, (int *)arg))
170			return -EFAULT;
171
172		if (options & WDIOS_DISABLECARD)
173			pnx833x_wdt_stop();
174
175		if (options & WDIOS_ENABLECARD)
176			pnx833x_wdt_start();
177
178		return 0;
179
180	case WDIOC_KEEPALIVE:
181		pnx833x_wdt_ping();
182		return 0;
183
184	case WDIOC_SETTIMEOUT:
185	{
186		if (get_user(new_timeout, (int *)arg))
187			return -EFAULT;
188
189		pnx833x_wdt_timeout = new_timeout;
190		PNX833X_REG(PNX833X_CONFIG +
191			PNX833X_CONFIG_CPU_WATCHDOG_COMPARE) = new_timeout;
192		return put_user(new_timeout, (int *)arg);
193	}
194
195	case WDIOC_GETTIMEOUT:
196		timeout = PNX833X_REG(PNX833X_CONFIG +
197					PNX833X_CONFIG_CPU_WATCHDOG_COMPARE);
198		return put_user(timeout, (int *)arg);
199
200	case WDIOC_GETTIMELEFT:
201		timeout_left = PNX833X_REG(PNX833X_CONFIG +
202						PNX833X_CONFIG_CPU_WATCHDOG);
203		return put_user(timeout_left, (int *)arg);
204
205	}
206}
207
208static int pnx833x_wdt_notify_sys(struct notifier_block *this,
209					unsigned long code, void *unused)
210{
211	if (code == SYS_DOWN || code == SYS_HALT)
212		pnx833x_wdt_stop(); /* Turn the WDT off */
213
214	return NOTIFY_DONE;
215}
216
217static const struct file_operations pnx833x_wdt_fops = {
218	.owner		= THIS_MODULE,
219	.llseek		= no_llseek,
220	.write		= pnx833x_wdt_write,
221	.unlocked_ioctl	= pnx833x_wdt_ioctl,
222	.open		= pnx833x_wdt_open,
223	.release	= pnx833x_wdt_release,
224};
225
226static struct miscdevice pnx833x_wdt_miscdev = {
227	.minor		= WATCHDOG_MINOR,
228	.name		= "watchdog",
229	.fops		= &pnx833x_wdt_fops,
230};
231
232static struct notifier_block pnx833x_wdt_notifier = {
233	.notifier_call = pnx833x_wdt_notify_sys,
234};
235
236static int __init watchdog_init(void)
237{
238	int ret, cause;
239
240	/* Lets check the reason for the reset.*/
241	cause = PNX833X_REG(PNX833X_RESET);
242	/*If bit 31 is set then watchdog was cause of reset.*/
243	if (cause & 0x80000000) {
244		pr_info("The system was previously reset due to the watchdog firing - please investigate...\n");
245	}
246
247	ret = register_reboot_notifier(&pnx833x_wdt_notifier);
248	if (ret) {
249		pr_err("cannot register reboot notifier (err=%d)\n", ret);
250		return ret;
251	}
252
253	ret = misc_register(&pnx833x_wdt_miscdev);
254	if (ret) {
255		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
256		       WATCHDOG_MINOR, ret);
257		unregister_reboot_notifier(&pnx833x_wdt_notifier);
258		return ret;
259	}
260
261	pr_info("Hardware Watchdog Timer for PNX833x: Version 0.1\n");
262
263	if (start_enabled)
264		pnx833x_wdt_start();
265
266	return 0;
267}
268
269static void __exit watchdog_exit(void)
270{
271	misc_deregister(&pnx833x_wdt_miscdev);
272	unregister_reboot_notifier(&pnx833x_wdt_notifier);
273}
274
275module_init(watchdog_init);
276module_exit(watchdog_exit);
277
278MODULE_AUTHOR("Daniel Laird/Andre McCurdy");
279MODULE_DESCRIPTION("Hardware Watchdog Device for PNX833x");
280MODULE_LICENSE("GPL");
281