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Lubomir Rintel938d0a82013-06-18 19:44:48 +02001/*
2 * Watchdog driver for Broadcom BCM2835
3 *
4 * "bcm2708_wdog" driver written by Luke Diamand that was obtained from
5 * branch "rpi-3.6.y" of git://github.com/raspberrypi/linux.git was used
6 * as a hardware reference for the Broadcom BCM2835 watchdog timer.
7 *
8 * Copyright (C) 2013 Lubomir Rintel <lkundrak@v3.sk>
9 *
10 * This program is free software; you can redistribute it and/or modify it
11 * under the terms of the GNU General Public License as published by the
12 * Free Software Foundation; either version 2 of the License, or (at your
13 * option) any later version.
14 */
15
Eric Anholt33a9f5b2015-04-24 12:08:54 -070016#include <linux/delay.h>
17#include <linux/reboot.h>
Lubomir Rintel938d0a82013-06-18 19:44:48 +020018#include <linux/types.h>
19#include <linux/module.h>
20#include <linux/io.h>
21#include <linux/watchdog.h>
22#include <linux/platform_device.h>
23#include <linux/of_address.h>
Eric Anholt33a9f5b2015-04-24 12:08:54 -070024#include <linux/of_platform.h>
Lubomir Rintel938d0a82013-06-18 19:44:48 +020025
26#define PM_RSTC 0x1c
Eric Anholt33a9f5b2015-04-24 12:08:54 -070027#define PM_RSTS 0x20
Lubomir Rintel938d0a82013-06-18 19:44:48 +020028#define PM_WDOG 0x24
29
30#define PM_PASSWORD 0x5a000000
31
32#define PM_WDOG_TIME_SET 0x000fffff
33#define PM_RSTC_WRCFG_CLR 0xffffffcf
Eric Anholt33a9f5b2015-04-24 12:08:54 -070034#define PM_RSTS_HADWRH_SET 0x00000040
Lubomir Rintel938d0a82013-06-18 19:44:48 +020035#define PM_RSTC_WRCFG_SET 0x00000030
36#define PM_RSTC_WRCFG_FULL_RESET 0x00000020
37#define PM_RSTC_RESET 0x00000102
38
39#define SECS_TO_WDOG_TICKS(x) ((x) << 16)
40#define WDOG_TICKS_TO_SECS(x) ((x) >> 16)
41
42struct bcm2835_wdt {
43 void __iomem *base;
44 spinlock_t lock;
Eric Anholt33a9f5b2015-04-24 12:08:54 -070045 struct notifier_block restart_handler;
Lubomir Rintel938d0a82013-06-18 19:44:48 +020046};
47
48static unsigned int heartbeat;
49static bool nowayout = WATCHDOG_NOWAYOUT;
50
51static int bcm2835_wdt_start(struct watchdog_device *wdog)
52{
53 struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
54 uint32_t cur;
55 unsigned long flags;
56
57 spin_lock_irqsave(&wdt->lock, flags);
58
59 writel_relaxed(PM_PASSWORD | (SECS_TO_WDOG_TICKS(wdog->timeout) &
60 PM_WDOG_TIME_SET), wdt->base + PM_WDOG);
61 cur = readl_relaxed(wdt->base + PM_RSTC);
62 writel_relaxed(PM_PASSWORD | (cur & PM_RSTC_WRCFG_CLR) |
63 PM_RSTC_WRCFG_FULL_RESET, wdt->base + PM_RSTC);
64
65 spin_unlock_irqrestore(&wdt->lock, flags);
66
67 return 0;
68}
69
70static int bcm2835_wdt_stop(struct watchdog_device *wdog)
71{
72 struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
73
74 writel_relaxed(PM_PASSWORD | PM_RSTC_RESET, wdt->base + PM_RSTC);
75 dev_info(wdog->dev, "Watchdog timer stopped");
76 return 0;
77}
78
79static int bcm2835_wdt_set_timeout(struct watchdog_device *wdog, unsigned int t)
80{
81 wdog->timeout = t;
82 return 0;
83}
84
85static unsigned int bcm2835_wdt_get_timeleft(struct watchdog_device *wdog)
86{
87 struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
88
89 uint32_t ret = readl_relaxed(wdt->base + PM_WDOG);
90 return WDOG_TICKS_TO_SECS(ret & PM_WDOG_TIME_SET);
91}
92
93static struct watchdog_ops bcm2835_wdt_ops = {
94 .owner = THIS_MODULE,
95 .start = bcm2835_wdt_start,
96 .stop = bcm2835_wdt_stop,
97 .set_timeout = bcm2835_wdt_set_timeout,
98 .get_timeleft = bcm2835_wdt_get_timeleft,
99};
100
101static struct watchdog_info bcm2835_wdt_info = {
102 .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
103 WDIOF_KEEPALIVEPING,
104 .identity = "Broadcom BCM2835 Watchdog timer",
105};
106
107static struct watchdog_device bcm2835_wdt_wdd = {
108 .info = &bcm2835_wdt_info,
109 .ops = &bcm2835_wdt_ops,
110 .min_timeout = 1,
111 .max_timeout = WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
112 .timeout = WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
113};
114
Eric Anholt33a9f5b2015-04-24 12:08:54 -0700115static int
116bcm2835_restart(struct notifier_block *this, unsigned long mode, void *cmd)
117{
118 struct bcm2835_wdt *wdt = container_of(this, struct bcm2835_wdt,
119 restart_handler);
120 u32 val;
121
122 /* use a timeout of 10 ticks (~150us) */
123 writel_relaxed(10 | PM_PASSWORD, wdt->base + PM_WDOG);
124 val = readl_relaxed(wdt->base + PM_RSTC);
125 val &= PM_RSTC_WRCFG_CLR;
126 val |= PM_PASSWORD | PM_RSTC_WRCFG_FULL_RESET;
127 writel_relaxed(val, wdt->base + PM_RSTC);
128
129 /* No sleeping, possibly atomic. */
130 mdelay(1);
131
132 return 0;
133}
134
135/*
136 * We can't really power off, but if we do the normal reset scheme, and
137 * indicate to bootcode.bin not to reboot, then most of the chip will be
138 * powered off.
139 */
140static void bcm2835_power_off(void)
141{
142 struct device_node *np =
143 of_find_compatible_node(NULL, NULL, "brcm,bcm2835-pm-wdt");
144 struct platform_device *pdev = of_find_device_by_node(np);
145 struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
146 u32 val;
147
148 /*
149 * We set the watchdog hard reset bit here to distinguish this reset
150 * from the normal (full) reset. bootcode.bin will not reboot after a
151 * hard reset.
152 */
153 val = readl_relaxed(wdt->base + PM_RSTS);
154 val &= PM_RSTC_WRCFG_CLR;
155 val |= PM_PASSWORD | PM_RSTS_HADWRH_SET;
156 writel_relaxed(val, wdt->base + PM_RSTS);
157
158 /* Continue with normal reset mechanism */
159 bcm2835_restart(&wdt->restart_handler, REBOOT_HARD, NULL);
160}
161
Lubomir Rintel938d0a82013-06-18 19:44:48 +0200162static int bcm2835_wdt_probe(struct platform_device *pdev)
163{
164 struct device *dev = &pdev->dev;
165 struct device_node *np = dev->of_node;
166 struct bcm2835_wdt *wdt;
167 int err;
168
169 wdt = devm_kzalloc(dev, sizeof(struct bcm2835_wdt), GFP_KERNEL);
Jingoo Han8deea832014-02-11 15:46:43 +0900170 if (!wdt)
Lubomir Rintel938d0a82013-06-18 19:44:48 +0200171 return -ENOMEM;
Lubomir Rintel938d0a82013-06-18 19:44:48 +0200172 platform_set_drvdata(pdev, wdt);
173
174 spin_lock_init(&wdt->lock);
175
176 wdt->base = of_iomap(np, 0);
177 if (!wdt->base) {
178 dev_err(dev, "Failed to remap watchdog regs");
179 return -ENODEV;
180 }
181
182 watchdog_set_drvdata(&bcm2835_wdt_wdd, wdt);
183 watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev);
184 watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout);
185 err = watchdog_register_device(&bcm2835_wdt_wdd);
186 if (err) {
187 dev_err(dev, "Failed to register watchdog device");
188 iounmap(wdt->base);
189 return err;
190 }
191
Eric Anholt33a9f5b2015-04-24 12:08:54 -0700192 wdt->restart_handler.notifier_call = bcm2835_restart;
193 wdt->restart_handler.priority = 128;
194 register_restart_handler(&wdt->restart_handler);
195 if (pm_power_off == NULL)
196 pm_power_off = bcm2835_power_off;
197
Lubomir Rintel938d0a82013-06-18 19:44:48 +0200198 dev_info(dev, "Broadcom BCM2835 watchdog timer");
199 return 0;
200}
201
202static int bcm2835_wdt_remove(struct platform_device *pdev)
203{
204 struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
205
Eric Anholt33a9f5b2015-04-24 12:08:54 -0700206 unregister_restart_handler(&wdt->restart_handler);
207 if (pm_power_off == bcm2835_power_off)
208 pm_power_off = NULL;
Lubomir Rintel938d0a82013-06-18 19:44:48 +0200209 watchdog_unregister_device(&bcm2835_wdt_wdd);
210 iounmap(wdt->base);
211
212 return 0;
213}
214
215static void bcm2835_wdt_shutdown(struct platform_device *pdev)
216{
217 bcm2835_wdt_stop(&bcm2835_wdt_wdd);
218}
219
220static const struct of_device_id bcm2835_wdt_of_match[] = {
221 { .compatible = "brcm,bcm2835-pm-wdt", },
222 {},
223};
224MODULE_DEVICE_TABLE(of, bcm2835_wdt_of_match);
225
226static struct platform_driver bcm2835_wdt_driver = {
227 .probe = bcm2835_wdt_probe,
228 .remove = bcm2835_wdt_remove,
229 .shutdown = bcm2835_wdt_shutdown,
230 .driver = {
231 .name = "bcm2835-wdt",
Lubomir Rintel938d0a82013-06-18 19:44:48 +0200232 .of_match_table = bcm2835_wdt_of_match,
233 },
234};
235module_platform_driver(bcm2835_wdt_driver);
236
237module_param(heartbeat, uint, 0);
238MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds");
239
240module_param(nowayout, bool, 0);
241MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
242 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
243
244MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
245MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer");
246MODULE_LICENSE("GPL");