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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Watchdog timer for PowerPC Book-E systems
4 *
5 * Author: Matthew McClintock
6 * Maintainer: Kumar Gala <galak@kernel.crashing.org>
7 *
8 * Copyright 2005, 2008, 2010-2011 Freescale Semiconductor Inc.
9 */
10
11#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12
13#include <linux/module.h>
14#include <linux/smp.h>
15#include <linux/watchdog.h>
16
17#include <asm/reg_booke.h>
18#include <asm/time.h>
19#include <asm/div64.h>
20
21/* If the kernel parameter wdt=1, the watchdog will be enabled at boot.
22 * Also, the wdt_period sets the watchdog timer period timeout.
23 * For E500 cpus the wdt_period sets which bit changing from 0->1 will
24 * trigger a watchdog timeout. This watchdog timeout will occur 3 times, the
25 * first time nothing will happen, the second time a watchdog exception will
26 * occur, and the final time the board will reset.
27 */
28
29
30#ifdef CONFIG_PPC_E500
31#define WDTP(x) ((((x)&0x3)<<30)|(((x)&0x3c)<<15))
32#define WDTP_MASK (WDTP(0x3f))
33#else
34#define WDTP(x) (TCR_WP(x))
35#define WDTP_MASK (TCR_WP_MASK)
36#endif
37
38static bool booke_wdt_enabled;
39module_param(booke_wdt_enabled, bool, 0);
40static int booke_wdt_period = CONFIG_BOOKE_WDT_DEFAULT_TIMEOUT;
41module_param(booke_wdt_period, int, 0);
42static bool nowayout = WATCHDOG_NOWAYOUT;
43module_param(nowayout, bool, 0);
44MODULE_PARM_DESC(nowayout,
45 "Watchdog cannot be stopped once started (default="
46 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
47
48#ifdef CONFIG_PPC_E500
49
50/* For the specified period, determine the number of seconds
51 * corresponding to the reset time. There will be a watchdog
52 * exception at approximately 3/5 of this time.
53 *
54 * The formula to calculate this is given by:
55 * 2.5 * (2^(63-period+1)) / timebase_freq
56 *
57 * In order to simplify things, we assume that period is
58 * at least 1. This will still result in a very long timeout.
59 */
60static unsigned long long period_to_sec(unsigned int period)
61{
62 unsigned long long tmp = 1ULL << (64 - period);
63 unsigned long tmp2 = ppc_tb_freq;
64
65 /* tmp may be a very large number and we don't want to overflow,
66 * so divide the timebase freq instead of multiplying tmp
67 */
68 tmp2 = tmp2 / 5 * 2;
69
70 do_div(tmp, tmp2);
71 return tmp;
72}
73
74/*
75 * This procedure will find the highest period which will give a timeout
76 * greater than the one required. e.g. for a bus speed of 66666666 and
77 * a parameter of 2 secs, then this procedure will return a value of 38.
78 */
79static unsigned int sec_to_period(unsigned int secs)
80{
81 unsigned int period;
82 for (period = 63; period > 0; period--) {
83 if (period_to_sec(period) >= secs)
84 return period;
85 }
86 return 0;
87}
88
89#define MAX_WDT_TIMEOUT period_to_sec(1)
90
91#else /* CONFIG_PPC_E500 */
92
93static unsigned long long period_to_sec(unsigned int period)
94{
95 return period;
96}
97
98static unsigned int sec_to_period(unsigned int secs)
99{
100 return secs;
101}
102
103#define MAX_WDT_TIMEOUT 3 /* from Kconfig */
104
105#endif /* !CONFIG_PPC_E500 */
106
107static void __booke_wdt_set(void *data)
108{
109 u32 val;
110 struct watchdog_device *wdog = data;
111
112 val = mfspr(SPRN_TCR);
113 val &= ~WDTP_MASK;
114 val |= WDTP(sec_to_period(wdog->timeout));
115
116 mtspr(SPRN_TCR, val);
117}
118
119static void booke_wdt_set(void *data)
120{
121 on_each_cpu(__booke_wdt_set, data, 0);
122}
123
124static void __booke_wdt_ping(void *data)
125{
126 mtspr(SPRN_TSR, TSR_ENW|TSR_WIS);
127}
128
129static int booke_wdt_ping(struct watchdog_device *wdog)
130{
131 on_each_cpu(__booke_wdt_ping, NULL, 0);
132
133 return 0;
134}
135
136static void __booke_wdt_enable(void *data)
137{
138 u32 val;
139 struct watchdog_device *wdog = data;
140
141 /* clear status before enabling watchdog */
142 __booke_wdt_ping(NULL);
143 val = mfspr(SPRN_TCR);
144 val &= ~WDTP_MASK;
145 val |= (TCR_WIE|TCR_WRC(WRC_CHIP)|WDTP(sec_to_period(wdog->timeout)));
146
147 mtspr(SPRN_TCR, val);
148}
149
150/**
151 * __booke_wdt_disable - disable the watchdog on the given CPU
152 *
153 * This function is called on each CPU. It disables the watchdog on that CPU.
154 *
155 * TCR[WRC] cannot be changed once it has been set to non-zero, but we can
156 * effectively disable the watchdog by setting its period to the maximum value.
157 */
158static void __booke_wdt_disable(void *data)
159{
160 u32 val;
161
162 val = mfspr(SPRN_TCR);
163 val &= ~(TCR_WIE | WDTP_MASK);
164 mtspr(SPRN_TCR, val);
165
166 /* clear status to make sure nothing is pending */
167 __booke_wdt_ping(NULL);
168
169}
170
171static int booke_wdt_start(struct watchdog_device *wdog)
172{
173 on_each_cpu(__booke_wdt_enable, wdog, 0);
174 pr_debug("watchdog enabled (timeout = %u sec)\n", wdog->timeout);
175
176 return 0;
177}
178
179static int booke_wdt_stop(struct watchdog_device *wdog)
180{
181 on_each_cpu(__booke_wdt_disable, NULL, 0);
182 pr_debug("watchdog disabled\n");
183
184 return 0;
185}
186
187static int booke_wdt_set_timeout(struct watchdog_device *wdt_dev,
188 unsigned int timeout)
189{
190 wdt_dev->timeout = timeout;
191 booke_wdt_set(wdt_dev);
192
193 return 0;
194}
195
196static struct watchdog_info booke_wdt_info __ro_after_init = {
197 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
198 .identity = "PowerPC Book-E Watchdog",
199};
200
201static const struct watchdog_ops booke_wdt_ops = {
202 .owner = THIS_MODULE,
203 .start = booke_wdt_start,
204 .stop = booke_wdt_stop,
205 .ping = booke_wdt_ping,
206 .set_timeout = booke_wdt_set_timeout,
207};
208
209static struct watchdog_device booke_wdt_dev = {
210 .info = &booke_wdt_info,
211 .ops = &booke_wdt_ops,
212 .min_timeout = 1,
213};
214
215static void __exit booke_wdt_exit(void)
216{
217 watchdog_unregister_device(&booke_wdt_dev);
218}
219
220static int __init booke_wdt_init(void)
221{
222 int ret = 0;
223
224 pr_info("powerpc book-e watchdog driver loaded\n");
225 booke_wdt_info.firmware_version = cur_cpu_spec->pvr_value;
226 booke_wdt_set_timeout(&booke_wdt_dev,
227 period_to_sec(booke_wdt_period));
228 watchdog_set_nowayout(&booke_wdt_dev, nowayout);
229 booke_wdt_dev.max_timeout = MAX_WDT_TIMEOUT;
230 if (booke_wdt_enabled)
231 booke_wdt_start(&booke_wdt_dev);
232
233 ret = watchdog_register_device(&booke_wdt_dev);
234
235 return ret;
236}
237
238module_init(booke_wdt_init);
239module_exit(booke_wdt_exit);
240
241MODULE_ALIAS("booke_wdt");
242MODULE_DESCRIPTION("PowerPC Book-E watchdog driver");
243MODULE_LICENSE("GPL");
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
33
34#ifdef CONFIG_PPC_FSL_BOOK3E
35#define WDTP(x) ((((x)&0x3)<<30)|(((x)&0x3c)<<15))
36#define WDTP_MASK (WDTP(0x3f))
37#else
38#define WDTP(x) (TCR_WP(x))
39#define WDTP_MASK (TCR_WP_MASK)
40#endif
41
42static bool booke_wdt_enabled;
43module_param(booke_wdt_enabled, bool, 0);
44static int booke_wdt_period = CONFIG_BOOKE_WDT_DEFAULT_TIMEOUT;
45module_param(booke_wdt_period, int, 0);
46
47#ifdef CONFIG_PPC_FSL_BOOK3E
48
49/* For the specified period, determine the number of seconds
50 * corresponding to the reset time. There will be a watchdog
51 * exception at approximately 3/5 of this time.
52 *
53 * The formula to calculate this is given by:
54 * 2.5 * (2^(63-period+1)) / timebase_freq
55 *
56 * In order to simplify things, we assume that period is
57 * at least 1. This will still result in a very long timeout.
58 */
59static unsigned long long period_to_sec(unsigned int period)
60{
61 unsigned long long tmp = 1ULL << (64 - period);
62 unsigned long tmp2 = ppc_tb_freq;
63
64 /* tmp may be a very large number and we don't want to overflow,
65 * so divide the timebase freq instead of multiplying tmp
66 */
67 tmp2 = tmp2 / 5 * 2;
68
69 do_div(tmp, tmp2);
70 return tmp;
71}
72
73/*
74 * This procedure will find the highest period which will give a timeout
75 * greater than the one required. e.g. for a bus speed of 66666666 and
76 * and a parameter of 2 secs, then this procedure will return a value of 38.
77 */
78static unsigned int sec_to_period(unsigned int secs)
79{
80 unsigned int period;
81 for (period = 63; period > 0; period--) {
82 if (period_to_sec(period) >= secs)
83 return period;
84 }
85 return 0;
86}
87
88#define MAX_WDT_TIMEOUT period_to_sec(1)
89
90#else /* CONFIG_PPC_FSL_BOOK3E */
91
92static unsigned long long period_to_sec(unsigned int period)
93{
94 return period;
95}
96
97static unsigned int sec_to_period(unsigned int secs)
98{
99 return secs;
100}
101
102#define MAX_WDT_TIMEOUT 3 /* from Kconfig */
103
104#endif /* !CONFIG_PPC_FSL_BOOK3E */
105
106static void __booke_wdt_set(void *data)
107{
108 u32 val;
109 struct watchdog_device *wdog = data;
110
111 val = mfspr(SPRN_TCR);
112 val &= ~WDTP_MASK;
113 val |= WDTP(sec_to_period(wdog->timeout));
114
115 mtspr(SPRN_TCR, val);
116}
117
118static void booke_wdt_set(void *data)
119{
120 on_each_cpu(__booke_wdt_set, data, 0);
121}
122
123static void __booke_wdt_ping(void *data)
124{
125 mtspr(SPRN_TSR, TSR_ENW|TSR_WIS);
126}
127
128static int booke_wdt_ping(struct watchdog_device *wdog)
129{
130 on_each_cpu(__booke_wdt_ping, NULL, 0);
131
132 return 0;
133}
134
135static void __booke_wdt_enable(void *data)
136{
137 u32 val;
138 struct watchdog_device *wdog = data;
139
140 /* clear status before enabling watchdog */
141 __booke_wdt_ping(NULL);
142 val = mfspr(SPRN_TCR);
143 val &= ~WDTP_MASK;
144 val |= (TCR_WIE|TCR_WRC(WRC_CHIP)|WDTP(sec_to_period(wdog->timeout)));
145
146 mtspr(SPRN_TCR, val);
147}
148
149/**
150 * booke_wdt_disable - disable the watchdog on the given CPU
151 *
152 * This function is called on each CPU. It disables the watchdog on that CPU.
153 *
154 * TCR[WRC] cannot be changed once it has been set to non-zero, but we can
155 * effectively disable the watchdog by setting its period to the maximum value.
156 */
157static void __booke_wdt_disable(void *data)
158{
159 u32 val;
160
161 val = mfspr(SPRN_TCR);
162 val &= ~(TCR_WIE | WDTP_MASK);
163 mtspr(SPRN_TCR, val);
164
165 /* clear status to make sure nothing is pending */
166 __booke_wdt_ping(NULL);
167
168}
169
170static int booke_wdt_start(struct watchdog_device *wdog)
171{
172 on_each_cpu(__booke_wdt_enable, wdog, 0);
173 pr_debug("watchdog enabled (timeout = %u sec)\n", wdog->timeout);
174
175 return 0;
176}
177
178static int booke_wdt_stop(struct watchdog_device *wdog)
179{
180 on_each_cpu(__booke_wdt_disable, NULL, 0);
181 pr_debug("watchdog disabled\n");
182
183 return 0;
184}
185
186static int booke_wdt_set_timeout(struct watchdog_device *wdt_dev,
187 unsigned int timeout)
188{
189 wdt_dev->timeout = timeout;
190 booke_wdt_set(wdt_dev);
191
192 return 0;
193}
194
195static struct watchdog_info booke_wdt_info = {
196 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
197 .identity = "PowerPC Book-E Watchdog",
198};
199
200static struct watchdog_ops booke_wdt_ops = {
201 .owner = THIS_MODULE,
202 .start = booke_wdt_start,
203 .stop = booke_wdt_stop,
204 .ping = booke_wdt_ping,
205 .set_timeout = booke_wdt_set_timeout,
206};
207
208static struct watchdog_device booke_wdt_dev = {
209 .info = &booke_wdt_info,
210 .ops = &booke_wdt_ops,
211 .min_timeout = 1,
212};
213
214static void __exit booke_wdt_exit(void)
215{
216 watchdog_unregister_device(&booke_wdt_dev);
217}
218
219static int __init booke_wdt_init(void)
220{
221 int ret = 0;
222 bool nowayout = WATCHDOG_NOWAYOUT;
223
224 pr_info("powerpc book-e watchdog driver loaded\n");
225 booke_wdt_info.firmware_version = cur_cpu_spec->pvr_value;
226 booke_wdt_set_timeout(&booke_wdt_dev,
227 period_to_sec(booke_wdt_period));
228 watchdog_set_nowayout(&booke_wdt_dev, nowayout);
229 booke_wdt_dev.max_timeout = MAX_WDT_TIMEOUT;
230 if (booke_wdt_enabled)
231 booke_wdt_start(&booke_wdt_dev);
232
233 ret = watchdog_register_device(&booke_wdt_dev);
234
235 return ret;
236}
237
238module_init(booke_wdt_init);
239module_exit(booke_wdt_exit);
240
241MODULE_ALIAS("booke_wdt");
242MODULE_DESCRIPTION("PowerPC Book-E watchdog driver");
243MODULE_LICENSE("GPL");