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/of_address.h>
27 #include <linux/of_platform.h>
28 #include <linux/module.h>
29 #include <linux/watchdog.h>
30 #include <linux/io.h>
31 #include <linux/uaccess.h>
32 #include <sysdev/fsl_soc.h>
33 
34 struct mpc8xxx_wdt {
35 	__be32 res0;
36 	__be32 swcrr; /* System watchdog control register */
37 #define SWCRR_SWTC 0xFFFF0000 /* Software Watchdog Time Count. */
38 #define SWCRR_SWEN 0x00000004 /* Watchdog Enable bit. */
39 #define SWCRR_SWRI 0x00000002 /* Software Watchdog Reset/Interrupt Select bit.*/
40 #define SWCRR_SWPR 0x00000001 /* Software Watchdog Counter Prescale bit. */
41 	__be32 swcnr; /* System watchdog count register */
42 	u8 res1[2];
43 	__be16 swsrr; /* System watchdog service register */
44 	u8 res2[0xF0];
45 };
46 
47 struct mpc8xxx_wdt_type {
48 	int prescaler;
49 	bool hw_enabled;
50 };
51 
52 struct mpc8xxx_wdt_ddata {
53 	struct mpc8xxx_wdt __iomem *base;
54 	struct watchdog_device wdd;
55 	struct timer_list timer;
56 	spinlock_t lock;
57 };
58 
59 static u16 timeout = 0xffff;
60 module_param(timeout, ushort, 0);
61 MODULE_PARM_DESC(timeout,
62 	"Watchdog timeout in ticks. (0<timeout<65536, default=65535)");
63 
64 static bool reset = 1;
65 module_param(reset, bool, 0);
66 MODULE_PARM_DESC(reset,
67 	"Watchdog Interrupt/Reset Mode. 0 = interrupt, 1 = reset");
68 
69 static bool nowayout = WATCHDOG_NOWAYOUT;
70 module_param(nowayout, bool, 0);
71 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
72 		 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
73 
74 static void mpc8xxx_wdt_keepalive(struct mpc8xxx_wdt_ddata *ddata)
75 {
76 	/* Ping the WDT */
77 	spin_lock(&ddata->lock);
78 	out_be16(&ddata->base->swsrr, 0x556c);
79 	out_be16(&ddata->base->swsrr, 0xaa39);
80 	spin_unlock(&ddata->lock);
81 }
82 
83 static void mpc8xxx_wdt_timer_ping(unsigned long arg)
84 {
85 	struct mpc8xxx_wdt_ddata *ddata = (void *)arg;
86 
87 	mpc8xxx_wdt_keepalive(ddata);
88 	/* We're pinging it twice faster than needed, just to be sure. */
89 	mod_timer(&ddata->timer, jiffies + HZ * ddata->wdd.timeout / 2);
90 }
91 
92 static int mpc8xxx_wdt_start(struct watchdog_device *w)
93 {
94 	struct mpc8xxx_wdt_ddata *ddata =
95 		container_of(w, struct mpc8xxx_wdt_ddata, wdd);
96 
97 	u32 tmp = SWCRR_SWEN | SWCRR_SWPR;
98 
99 	/* Good, fire up the show */
100 	if (reset)
101 		tmp |= SWCRR_SWRI;
102 
103 	tmp |= timeout << 16;
104 
105 	out_be32(&ddata->base->swcrr, tmp);
106 
107 	del_timer_sync(&ddata->timer);
108 
109 	return 0;
110 }
111 
112 static int mpc8xxx_wdt_ping(struct watchdog_device *w)
113 {
114 	struct mpc8xxx_wdt_ddata *ddata =
115 		container_of(w, struct mpc8xxx_wdt_ddata, wdd);
116 
117 	mpc8xxx_wdt_keepalive(ddata);
118 	return 0;
119 }
120 
121 static int mpc8xxx_wdt_stop(struct watchdog_device *w)
122 {
123 	struct mpc8xxx_wdt_ddata *ddata =
124 		container_of(w, struct mpc8xxx_wdt_ddata, wdd);
125 
126 	mod_timer(&ddata->timer, jiffies);
127 	return 0;
128 }
129 
130 static struct watchdog_info mpc8xxx_wdt_info = {
131 	.options = WDIOF_KEEPALIVEPING,
132 	.firmware_version = 1,
133 	.identity = "MPC8xxx",
134 };
135 
136 static struct watchdog_ops mpc8xxx_wdt_ops = {
137 	.owner = THIS_MODULE,
138 	.start = mpc8xxx_wdt_start,
139 	.ping = mpc8xxx_wdt_ping,
140 	.stop = mpc8xxx_wdt_stop,
141 };
142 
143 static int mpc8xxx_wdt_probe(struct platform_device *ofdev)
144 {
145 	int ret;
146 	struct resource *res;
147 	const struct mpc8xxx_wdt_type *wdt_type;
148 	struct mpc8xxx_wdt_ddata *ddata;
149 	u32 freq = fsl_get_sys_freq();
150 	bool enabled;
151 	unsigned int timeout_sec;
152 
153 	wdt_type = of_device_get_match_data(&ofdev->dev);
154 	if (!wdt_type)
155 		return -EINVAL;
156 
157 	if (!freq || freq == -1)
158 		return -EINVAL;
159 
160 	ddata = devm_kzalloc(&ofdev->dev, sizeof(*ddata), GFP_KERNEL);
161 	if (!ddata)
162 		return -ENOMEM;
163 
164 	res = platform_get_resource(ofdev, IORESOURCE_MEM, 0);
165 	ddata->base = devm_ioremap_resource(&ofdev->dev, res);
166 	if (IS_ERR(ddata->base))
167 		return PTR_ERR(ddata->base);
168 
169 	enabled = in_be32(&ddata->base->swcrr) & SWCRR_SWEN;
170 	if (!enabled && wdt_type->hw_enabled) {
171 		pr_info("could not be enabled in software\n");
172 		return -ENODEV;
173 	}
174 
175 	spin_lock_init(&ddata->lock);
176 	setup_timer(&ddata->timer, mpc8xxx_wdt_timer_ping,
177 		    (unsigned long)ddata);
178 
179 	ddata->wdd.info = &mpc8xxx_wdt_info,
180 	ddata->wdd.ops = &mpc8xxx_wdt_ops,
181 
182 	/* Calculate the timeout in seconds */
183 	timeout_sec = (timeout * wdt_type->prescaler) / freq;
184 
185 	ddata->wdd.timeout = timeout_sec;
186 
187 	watchdog_set_nowayout(&ddata->wdd, nowayout);
188 
189 	ret = watchdog_register_device(&ddata->wdd);
190 	if (ret) {
191 		pr_err("cannot register watchdog device (err=%d)\n", ret);
192 		return ret;
193 	}
194 
195 	pr_info("WDT driver for MPC8xxx initialized. mode:%s timeout=%d (%d seconds)\n",
196 		reset ? "reset" : "interrupt", timeout, timeout_sec);
197 
198 	/*
199 	 * If the watchdog was previously enabled or we're running on
200 	 * MPC8xxx, we should ping the wdt from the kernel until the
201 	 * userspace handles it.
202 	 */
203 	if (enabled)
204 		mod_timer(&ddata->timer, jiffies);
205 
206 	platform_set_drvdata(ofdev, ddata);
207 	return 0;
208 }
209 
210 static int mpc8xxx_wdt_remove(struct platform_device *ofdev)
211 {
212 	struct mpc8xxx_wdt_ddata *ddata = platform_get_drvdata(ofdev);
213 
214 	pr_crit("Watchdog removed, expect the %s soon!\n",
215 		reset ? "reset" : "machine check exception");
216 	del_timer_sync(&ddata->timer);
217 	watchdog_unregister_device(&ddata->wdd);
218 
219 	return 0;
220 }
221 
222 static 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 };
245 MODULE_DEVICE_TABLE(of, mpc8xxx_wdt_match);
246 
247 static 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 static int __init mpc8xxx_wdt_init(void)
257 {
258 	return platform_driver_register(&mpc8xxx_wdt_driver);
259 }
260 arch_initcall(mpc8xxx_wdt_init);
261 
262 static void __exit mpc8xxx_wdt_exit(void)
263 {
264 	platform_driver_unregister(&mpc8xxx_wdt_driver);
265 }
266 module_exit(mpc8xxx_wdt_exit);
267 
268 MODULE_AUTHOR("Dave Updegraff, Kumar Gala");
269 MODULE_DESCRIPTION("Driver for watchdog timer in MPC8xx/MPC83xx/MPC86xx "
270 		   "uProcessors");
271 MODULE_LICENSE("GPL");
272