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Linux/drivers/watchdog/mpc8xxx_wdt.c

  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 
 35 struct 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 
 48 struct mpc8xxx_wdt_type {
 49         int prescaler;
 50         bool hw_enabled;
 51 };
 52 
 53 static struct mpc8xxx_wdt __iomem *wd_base;
 54 static int mpc8xxx_wdt_init_late(void);
 55 
 56 static u16 timeout = 0xffff;
 57 module_param(timeout, ushort, 0);
 58 MODULE_PARM_DESC(timeout,
 59         "Watchdog timeout in ticks. (0<timeout<65536, default=65535)");
 60 
 61 static bool reset = 1;
 62 module_param(reset, bool, 0);
 63 MODULE_PARM_DESC(reset,
 64         "Watchdog Interrupt/Reset Mode. 0 = interrupt, 1 = reset");
 65 
 66 static bool nowayout = WATCHDOG_NOWAYOUT;
 67 module_param(nowayout, bool, 0);
 68 MODULE_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  */
 75 static int prescale = 1;
 76 
 77 static DEFINE_SPINLOCK(wdt_spinlock);
 78 
 79 static 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 
 88 static struct watchdog_device mpc8xxx_wdt_dev;
 89 static void mpc8xxx_wdt_timer_ping(unsigned long arg);
 90 static DEFINE_TIMER(wdt_timer, mpc8xxx_wdt_timer_ping, 0,
 91                 (unsigned long)&mpc8xxx_wdt_dev);
 92 
 93 static 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 
102 static 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 
121 static int mpc8xxx_wdt_ping(struct watchdog_device *w)
122 {
123         mpc8xxx_wdt_keepalive();
124         return 0;
125 }
126 
127 static int mpc8xxx_wdt_stop(struct watchdog_device *w)
128 {
129         mod_timer(&wdt_timer, jiffies);
130         return 0;
131 }
132 
133 static struct watchdog_info mpc8xxx_wdt_info = {
134         .options = WDIOF_KEEPALIVEPING,
135         .firmware_version = 1,
136         .identity = "MPC8xxx",
137 };
138 
139 static 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 
146 static struct watchdog_device mpc8xxx_wdt_dev = {
147         .info = &mpc8xxx_wdt_info,
148         .ops = &mpc8xxx_wdt_ops,
149 };
150 
151 static const struct of_device_id mpc8xxx_wdt_match[];
152 static 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;
205 err_unmap:
206         iounmap(wd_base);
207         wd_base = NULL;
208         return ret;
209 }
210 
211 static 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 
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                 .owner = THIS_MODULE,
253                 .of_match_table = mpc8xxx_wdt_match,
254         },
255 };
256 
257 /*
258  * We do wdt initialization in two steps: arch_initcall probes the wdt
259  * very early to start pinging the watchdog (misc devices are not yet
260  * available), and later module_init() just registers the misc device.
261  */
262 static int mpc8xxx_wdt_init_late(void)
263 {
264         int ret;
265 
266         if (!wd_base)
267                 return -ENODEV;
268 
269         watchdog_set_nowayout(&mpc8xxx_wdt_dev, nowayout);
270 
271         ret = watchdog_register_device(&mpc8xxx_wdt_dev);
272         if (ret) {
273                 pr_err("cannot register watchdog device (err=%d)\n", ret);
274                 return ret;
275         }
276         return 0;
277 }
278 #ifndef MODULE
279 module_init(mpc8xxx_wdt_init_late);
280 #endif
281 
282 static int __init mpc8xxx_wdt_init(void)
283 {
284         return platform_driver_register(&mpc8xxx_wdt_driver);
285 }
286 arch_initcall(mpc8xxx_wdt_init);
287 
288 static void __exit mpc8xxx_wdt_exit(void)
289 {
290         platform_driver_unregister(&mpc8xxx_wdt_driver);
291 }
292 module_exit(mpc8xxx_wdt_exit);
293 
294 MODULE_AUTHOR("Dave Updegraff, Kumar Gala");
295 MODULE_DESCRIPTION("Driver for watchdog timer in MPC8xx/MPC83xx/MPC86xx "
296                    "uProcessors");
297 MODULE_LICENSE("GPL");
298 

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