tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * Watchdog timer for PowerPC Book-E systems
3 *
4 * Author: Matthew McClintock
5 * Maintainer: Kumar Gala <galak@kernel.crashing.org>
6 *
7 * Copyright 2005, 2008, 2010-2011 Freescale Semiconductor Inc.
8 *
9 * This program is free software; you can redistribute it and/or modify it
10 * under the terms of the GNU General Public License as published by the
11 * Free Software Foundation; either version 2 of the License, or (at your
12 * option) any later version.
13 */
14
15#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
16
17#include <linux/module.h>
18#include <linux/smp.h>
19#include <linux/watchdog.h>
20
21#include <asm/reg_booke.h>
22#include <asm/time.h>
23#include <asm/div64.h>
24
25/* If the kernel parameter wdt=1, the watchdog will be enabled at boot.
26 * Also, the wdt_period sets the watchdog timer period timeout.
27 * For E500 cpus the wdt_period sets which bit changing from 0->1 will
28 * trigger a watchog timeout. This watchdog timeout will occur 3 times, the
29 * first time nothing will happen, the second time a watchdog exception will
30 * occur, and the final time the board will reset.
31 */
32
33u32 booke_wdt_enabled;
34u32 booke_wdt_period = CONFIG_BOOKE_WDT_DEFAULT_TIMEOUT;
35
36#ifdef CONFIG_PPC_FSL_BOOK3E
37#define WDTP(x) ((((x)&0x3)<<30)|(((x)&0x3c)<<15))
38#define WDTP_MASK (WDTP(0x3f))
39#else
40#define WDTP(x) (TCR_WP(x))
41#define WDTP_MASK (TCR_WP_MASK)
42#endif
43
44#ifdef CONFIG_PPC_FSL_BOOK3E
45
46/* For the specified period, determine the number of seconds
47 * corresponding to the reset time. There will be a watchdog
48 * exception at approximately 3/5 of this time.
49 *
50 * The formula to calculate this is given by:
51 * 2.5 * (2^(63-period+1)) / timebase_freq
52 *
53 * In order to simplify things, we assume that period is
54 * at least 1. This will still result in a very long timeout.
55 */
56static unsigned long long period_to_sec(unsigned int period)
57{
58 unsigned long long tmp = 1ULL << (64 - period);
59 unsigned long tmp2 = ppc_tb_freq;
60
61 /* tmp may be a very large number and we don't want to overflow,
62 * so divide the timebase freq instead of multiplying tmp
63 */
64 tmp2 = tmp2 / 5 * 2;
65
66 do_div(tmp, tmp2);
67 return tmp;
68}
69
70/*
71 * This procedure will find the highest period which will give a timeout
72 * greater than the one required. e.g. for a bus speed of 66666666 and
73 * and a parameter of 2 secs, then this procedure will return a value of 38.
74 */
75static unsigned int sec_to_period(unsigned int secs)
76{
77 unsigned int period;
78 for (period = 63; period > 0; period--) {
79 if (period_to_sec(period) >= secs)
80 return period;
81 }
82 return 0;
83}
84
85#define MAX_WDT_TIMEOUT period_to_sec(1)
86
87#else /* CONFIG_PPC_FSL_BOOK3E */
88
89static unsigned long long period_to_sec(unsigned int period)
90{
91 return period;
92}
93
94static unsigned int sec_to_period(unsigned int secs)
95{
96 return secs;
97}
98
99#define MAX_WDT_TIMEOUT 3 /* from Kconfig */
100
101#endif /* !CONFIG_PPC_FSL_BOOK3E */
102
103static void __booke_wdt_set(void *data)
104{
105 u32 val;
106
107 val = mfspr(SPRN_TCR);
108 val &= ~WDTP_MASK;
109 val |= WDTP(booke_wdt_period);
110
111 mtspr(SPRN_TCR, val);
112}
113
114static void booke_wdt_set(void)
115{
116 on_each_cpu(__booke_wdt_set, NULL, 0);
117}
118
119static void __booke_wdt_ping(void *data)
120{
121 mtspr(SPRN_TSR, TSR_ENW|TSR_WIS);
122}
123
124static int booke_wdt_ping(struct watchdog_device *wdog)
125{
126 on_each_cpu(__booke_wdt_ping, NULL, 0);
127
128 return 0;
129}
130
131static void __booke_wdt_enable(void *data)
132{
133 u32 val;
134
135 /* clear status before enabling watchdog */
136 __booke_wdt_ping(NULL);
137 val = mfspr(SPRN_TCR);
138 val &= ~WDTP_MASK;
139 val |= (TCR_WIE|TCR_WRC(WRC_CHIP)|WDTP(booke_wdt_period));
140
141 mtspr(SPRN_TCR, val);
142}
143
144/**
145 * booke_wdt_disable - disable the watchdog on the given CPU
146 *
147 * This function is called on each CPU. It disables the watchdog on that CPU.
148 *
149 * TCR[WRC] cannot be changed once it has been set to non-zero, but we can
150 * effectively disable the watchdog by setting its period to the maximum value.
151 */
152static void __booke_wdt_disable(void *data)
153{
154 u32 val;
155
156 val = mfspr(SPRN_TCR);
157 val &= ~(TCR_WIE | WDTP_MASK);
158 mtspr(SPRN_TCR, val);
159
160 /* clear status to make sure nothing is pending */
161 __booke_wdt_ping(NULL);
162
163}
164
165static void __booke_wdt_start(struct watchdog_device *wdog)
166{
167 on_each_cpu(__booke_wdt_enable, NULL, 0);
168 pr_debug("watchdog enabled (timeout = %u sec)\n", wdog->timeout);
169}
170
171static int booke_wdt_start(struct watchdog_device *wdog)
172{
173 if (booke_wdt_enabled == 0) {
174 booke_wdt_enabled = 1;
175 __booke_wdt_start(wdog);
176 }
177 return 0;
178}
179
180static int booke_wdt_stop(struct watchdog_device *wdog)
181{
182 on_each_cpu(__booke_wdt_disable, NULL, 0);
183 booke_wdt_enabled = 0;
184 pr_debug("watchdog disabled\n");
185
186 return 0;
187}
188
189static int booke_wdt_set_timeout(struct watchdog_device *wdt_dev,
190 unsigned int timeout)
191{
192 if (timeout > MAX_WDT_TIMEOUT)
193 return -EINVAL;
194 booke_wdt_period = sec_to_period(timeout);
195 wdt_dev->timeout = timeout;
196 booke_wdt_set();
197
198 return 0;
199}
200
201static struct watchdog_info booke_wdt_info = {
202 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
203 .identity = "PowerPC Book-E Watchdog",
204};
205
206static struct watchdog_ops booke_wdt_ops = {
207 .owner = THIS_MODULE,
208 .start = booke_wdt_start,
209 .stop = booke_wdt_stop,
210 .ping = booke_wdt_ping,
211 .set_timeout = booke_wdt_set_timeout,
212};
213
214static struct watchdog_device booke_wdt_dev = {
215 .info = &booke_wdt_info,
216 .ops = &booke_wdt_ops,
217 .min_timeout = 1,
218 .max_timeout = 0xFFFF
219};
220
221static void __exit booke_wdt_exit(void)
222{
223 watchdog_unregister_device(&booke_wdt_dev);
224}
225
226static int __init booke_wdt_init(void)
227{
228 int ret = 0;
229 bool nowayout = WATCHDOG_NOWAYOUT;
230
231 pr_info("powerpc book-e watchdog driver loaded\n");
232 booke_wdt_info.firmware_version = cur_cpu_spec->pvr_value;
233 booke_wdt_set_timeout(&booke_wdt_dev,
234 period_to_sec(CONFIG_BOOKE_WDT_DEFAULT_TIMEOUT));
235 watchdog_set_nowayout(&booke_wdt_dev, nowayout);
236 if (booke_wdt_enabled)
237 __booke_wdt_start(&booke_wdt_dev);
238
239 ret = watchdog_register_device(&booke_wdt_dev);
240
241 return ret;
242}
243
244module_init(booke_wdt_init);
245module_exit(booke_wdt_exit);
246
247MODULE_DESCRIPTION("PowerPC Book-E watchdog driver");
248MODULE_LICENSE("GPL");