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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
21
22#include <linux/fs.h>
23#include <linux/init.h>
24#include <linux/kernel.h>
25#include <linux/timer.h>
26#include <linux/miscdevice.h>
27#include <linux/of_address.h>
28#include <linux/of_platform.h>
29#include <linux/module.h>
30#include <linux/watchdog.h>
31#include <linux/io.h>
32#include <linux/uaccess.h>
33#include <sysdev/fsl_soc.h>
34
35struct mpc8xxx_wdt {
36	__be32 res0;
37	__be32 swcrr; /* System watchdog control register */
38#define SWCRR_SWTC 0xFFFF0000 /* Software Watchdog Time Count. */
39#define SWCRR_SWEN 0x00000004 /* Watchdog Enable bit. */
40#define SWCRR_SWRI 0x00000002 /* Software Watchdog Reset/Interrupt Select bit.*/
41#define SWCRR_SWPR 0x00000001 /* Software Watchdog Counter Prescale bit. */
42	__be32 swcnr; /* System watchdog count register */
43	u8 res1[2];
44	__be16 swsrr; /* System watchdog service register */
45	u8 res2[0xF0];
46};
47
48struct mpc8xxx_wdt_type {
49	int prescaler;
50	bool hw_enabled;
51};
52
53static struct mpc8xxx_wdt __iomem *wd_base;
54static int mpc8xxx_wdt_init_late(void);
55
56static u16 timeout = 0xffff;
57module_param(timeout, ushort, 0);
58MODULE_PARM_DESC(timeout,
59	"Watchdog timeout in ticks. (0<timeout<65536, default=65535)");
60
61static bool reset = 1;
62module_param(reset, bool, 0);
63MODULE_PARM_DESC(reset,
64	"Watchdog Interrupt/Reset Mode. 0 = interrupt, 1 = reset");
65
66static bool nowayout = WATCHDOG_NOWAYOUT;
67module_param(nowayout, bool, 0);
68MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
69		 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
70
71/*
72 * We always prescale, but if someone really doesn't want to they can set this
73 * to 0
74 */
75static int prescale = 1;
76
77static DEFINE_SPINLOCK(wdt_spinlock);
78
79static void mpc8xxx_wdt_keepalive(void)
80{
81	/* Ping the WDT */
82	spin_lock(&wdt_spinlock);
83	out_be16(&wd_base->swsrr, 0x556c);
84	out_be16(&wd_base->swsrr, 0xaa39);
85	spin_unlock(&wdt_spinlock);
86}
87
88static struct watchdog_device mpc8xxx_wdt_dev;
89static void mpc8xxx_wdt_timer_ping(unsigned long arg);
90static DEFINE_TIMER(wdt_timer, mpc8xxx_wdt_timer_ping, 0,
91		(unsigned long)&mpc8xxx_wdt_dev);
92
93static void mpc8xxx_wdt_timer_ping(unsigned long arg)
94{
95	struct watchdog_device *w = (struct watchdog_device *)arg;
96
97	mpc8xxx_wdt_keepalive();
98	/* We're pinging it twice faster than needed, just to be sure. */
99	mod_timer(&wdt_timer, jiffies + HZ * w->timeout / 2);
100}
101
102static int mpc8xxx_wdt_start(struct watchdog_device *w)
103{
104	u32 tmp = SWCRR_SWEN;
105
106	/* Good, fire up the show */
107	if (prescale)
108		tmp |= SWCRR_SWPR;
109	if (reset)
110		tmp |= SWCRR_SWRI;
111
112	tmp |= timeout << 16;
113
114	out_be32(&wd_base->swcrr, tmp);
115
116	del_timer_sync(&wdt_timer);
117
118	return 0;
119}
120
121static int mpc8xxx_wdt_ping(struct watchdog_device *w)
122{
123	mpc8xxx_wdt_keepalive();
124	return 0;
125}
126
127static int mpc8xxx_wdt_stop(struct watchdog_device *w)
128{
129	mod_timer(&wdt_timer, jiffies);
130	return 0;
131}
132
133static struct watchdog_info mpc8xxx_wdt_info = {
134	.options = WDIOF_KEEPALIVEPING,
135	.firmware_version = 1,
136	.identity = "MPC8xxx",
137};
138
139static struct watchdog_ops mpc8xxx_wdt_ops = {
140	.owner = THIS_MODULE,
141	.start = mpc8xxx_wdt_start,
142	.ping = mpc8xxx_wdt_ping,
143	.stop = mpc8xxx_wdt_stop,
144};
145
146static struct watchdog_device mpc8xxx_wdt_dev = {
147	.info = &mpc8xxx_wdt_info,
148	.ops = &mpc8xxx_wdt_ops,
149};
150
151static const struct of_device_id mpc8xxx_wdt_match[];
152static int mpc8xxx_wdt_probe(struct platform_device *ofdev)
153{
154	int ret;
155	const struct of_device_id *match;
156	struct device_node *np = ofdev->dev.of_node;
157	const struct mpc8xxx_wdt_type *wdt_type;
158	u32 freq = fsl_get_sys_freq();
159	bool enabled;
160	unsigned int timeout_sec;
161
162	match = of_match_device(mpc8xxx_wdt_match, &ofdev->dev);
163	if (!match)
164		return -EINVAL;
165	wdt_type = match->data;
166
167	if (!freq || freq == -1)
168		return -EINVAL;
169
170	wd_base = of_iomap(np, 0);
171	if (!wd_base)
172		return -ENOMEM;
173
174	enabled = in_be32(&wd_base->swcrr) & SWCRR_SWEN;
175	if (!enabled && wdt_type->hw_enabled) {
176		pr_info("could not be enabled in software\n");
177		ret = -ENOSYS;
178		goto err_unmap;
179	}
180
181	/* Calculate the timeout in seconds */
182	if (prescale)
183		timeout_sec = (timeout * wdt_type->prescaler) / freq;
184	else
185		timeout_sec = timeout / freq;
186
187	mpc8xxx_wdt_dev.timeout = timeout_sec;
188#ifdef MODULE
189	ret = mpc8xxx_wdt_init_late();
190	if (ret)
191		goto err_unmap;
192#endif
193
194	pr_info("WDT driver for MPC8xxx initialized. mode:%s timeout=%d (%d seconds)\n",
195		reset ? "reset" : "interrupt", timeout, timeout_sec);
196
197	/*
198	 * If the watchdog was previously enabled or we're running on
199	 * MPC8xxx, we should ping the wdt from the kernel until the
200	 * userspace handles it.
201	 */
202	if (enabled)
203		mod_timer(&wdt_timer, jiffies);
204	return 0;
205err_unmap:
206	iounmap(wd_base);
207	wd_base = NULL;
208	return ret;
209}
210
211static int mpc8xxx_wdt_remove(struct platform_device *ofdev)
212{
213	pr_crit("Watchdog removed, expect the %s soon!\n",
214		reset ? "reset" : "machine check exception");
215	del_timer_sync(&wdt_timer);
216	watchdog_unregister_device(&mpc8xxx_wdt_dev);
217	iounmap(wd_base);
218
219	return 0;
220}
221
222static const struct of_device_id mpc8xxx_wdt_match[] = {
223	{
224		.compatible = "mpc83xx_wdt",
225		.data = &(struct mpc8xxx_wdt_type) {
226			.prescaler = 0x10000,
227		},
228	},
229	{
230		.compatible = "fsl,mpc8610-wdt",
231		.data = &(struct mpc8xxx_wdt_type) {
232			.prescaler = 0x10000,
233			.hw_enabled = true,
234		},
235	},
236	{
237		.compatible = "fsl,mpc823-wdt",
238		.data = &(struct mpc8xxx_wdt_type) {
239			.prescaler = 0x800,
240			.hw_enabled = true,
241		},
242	},
243	{},
244};
245MODULE_DEVICE_TABLE(of, mpc8xxx_wdt_match);
246
247static struct platform_driver mpc8xxx_wdt_driver = {
248	.probe		= mpc8xxx_wdt_probe,
249	.remove		= mpc8xxx_wdt_remove,
250	.driver = {
251		.name = "mpc8xxx_wdt",
252		.of_match_table = mpc8xxx_wdt_match,
253	},
254};
255
256/*
257 * We do wdt initialization in two steps: arch_initcall probes the wdt
258 * very early to start pinging the watchdog (misc devices are not yet
259 * available), and later module_init() just registers the misc device.
260 */
261static int mpc8xxx_wdt_init_late(void)
262{
263	int ret;
264
265	if (!wd_base)
266		return -ENODEV;
267
268	watchdog_set_nowayout(&mpc8xxx_wdt_dev, nowayout);
269
270	ret = watchdog_register_device(&mpc8xxx_wdt_dev);
271	if (ret) {
272		pr_err("cannot register watchdog device (err=%d)\n", ret);
273		return ret;
274	}
275	return 0;
276}
277#ifndef MODULE
278module_init(mpc8xxx_wdt_init_late);
279#endif
280
281static int __init mpc8xxx_wdt_init(void)
282{
283	return platform_driver_register(&mpc8xxx_wdt_driver);
284}
285arch_initcall(mpc8xxx_wdt_init);
286
287static void __exit mpc8xxx_wdt_exit(void)
288{
289	platform_driver_unregister(&mpc8xxx_wdt_driver);
290}
291module_exit(mpc8xxx_wdt_exit);
292
293MODULE_AUTHOR("Dave Updegraff, Kumar Gala");
294MODULE_DESCRIPTION("Driver for watchdog timer in MPC8xx/MPC83xx/MPC86xx "
295		   "uProcessors");
296MODULE_LICENSE("GPL");
297