1/*
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
16#include <linux/delay.h>
17#include <linux/reboot.h>
18#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>
24#include <linux/of_platform.h>
25
26#define PM_RSTC				0x1c
27#define PM_RSTS				0x20
28#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
34#define PM_RSTS_HADWRH_SET		0x00000040
35#define PM_RSTC_WRCFG_SET		0x00000030
36#define PM_RSTC_WRCFG_FULL_RESET	0x00000020
37#define PM_RSTC_RESET			0x00000102
38
39/*
40 * The Raspberry Pi firmware uses the RSTS register to know which partiton
41 * to boot from. The partiton value is spread into bits 0, 2, 4, 6, 8, 10.
42 * Partiton 63 is a special partition used by the firmware to indicate halt.
43 */
44#define PM_RSTS_RASPBERRYPI_HALT	0x555
45
46#define SECS_TO_WDOG_TICKS(x) ((x) << 16)
47#define WDOG_TICKS_TO_SECS(x) ((x) >> 16)
48
49struct bcm2835_wdt {
50	void __iomem		*base;
51	spinlock_t		lock;
52	struct notifier_block	restart_handler;
53};
54
55static unsigned int heartbeat;
56static bool nowayout = WATCHDOG_NOWAYOUT;
57
58static int bcm2835_wdt_start(struct watchdog_device *wdog)
59{
60	struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
61	uint32_t cur;
62	unsigned long flags;
63
64	spin_lock_irqsave(&wdt->lock, flags);
65
66	writel_relaxed(PM_PASSWORD | (SECS_TO_WDOG_TICKS(wdog->timeout) &
67				PM_WDOG_TIME_SET), wdt->base + PM_WDOG);
68	cur = readl_relaxed(wdt->base + PM_RSTC);
69	writel_relaxed(PM_PASSWORD | (cur & PM_RSTC_WRCFG_CLR) |
70		  PM_RSTC_WRCFG_FULL_RESET, wdt->base + PM_RSTC);
71
72	spin_unlock_irqrestore(&wdt->lock, flags);
73
74	return 0;
75}
76
77static int bcm2835_wdt_stop(struct watchdog_device *wdog)
78{
79	struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
80
81	writel_relaxed(PM_PASSWORD | PM_RSTC_RESET, wdt->base + PM_RSTC);
82	dev_info(wdog->dev, "Watchdog timer stopped");
83	return 0;
84}
85
86static int bcm2835_wdt_set_timeout(struct watchdog_device *wdog, unsigned int t)
87{
88	wdog->timeout = t;
89	return 0;
90}
91
92static unsigned int bcm2835_wdt_get_timeleft(struct watchdog_device *wdog)
93{
94	struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
95
96	uint32_t ret = readl_relaxed(wdt->base + PM_WDOG);
97	return WDOG_TICKS_TO_SECS(ret & PM_WDOG_TIME_SET);
98}
99
100static struct watchdog_ops bcm2835_wdt_ops = {
101	.owner =	THIS_MODULE,
102	.start =	bcm2835_wdt_start,
103	.stop =		bcm2835_wdt_stop,
104	.set_timeout =	bcm2835_wdt_set_timeout,
105	.get_timeleft =	bcm2835_wdt_get_timeleft,
106};
107
108static struct watchdog_info bcm2835_wdt_info = {
109	.options =	WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
110			WDIOF_KEEPALIVEPING,
111	.identity =	"Broadcom BCM2835 Watchdog timer",
112};
113
114static struct watchdog_device bcm2835_wdt_wdd = {
115	.info =		&bcm2835_wdt_info,
116	.ops =		&bcm2835_wdt_ops,
117	.min_timeout =	1,
118	.max_timeout =	WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
119	.timeout =	WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
120};
121
122static int
123bcm2835_restart(struct notifier_block *this, unsigned long mode, void *cmd)
124{
125	struct bcm2835_wdt *wdt = container_of(this, struct bcm2835_wdt,
126					       restart_handler);
127	u32 val;
128
129	/* use a timeout of 10 ticks (~150us) */
130	writel_relaxed(10 | PM_PASSWORD, wdt->base + PM_WDOG);
131	val = readl_relaxed(wdt->base + PM_RSTC);
132	val &= PM_RSTC_WRCFG_CLR;
133	val |= PM_PASSWORD | PM_RSTC_WRCFG_FULL_RESET;
134	writel_relaxed(val, wdt->base + PM_RSTC);
135
136	/* No sleeping, possibly atomic. */
137	mdelay(1);
138
139	return 0;
140}
141
142/*
143 * We can't really power off, but if we do the normal reset scheme, and
144 * indicate to bootcode.bin not to reboot, then most of the chip will be
145 * powered off.
146 */
147static void bcm2835_power_off(void)
148{
149	struct device_node *np =
150		of_find_compatible_node(NULL, NULL, "brcm,bcm2835-pm-wdt");
151	struct platform_device *pdev = of_find_device_by_node(np);
152	struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
153	u32 val;
154
155	/*
156	 * We set the watchdog hard reset bit here to distinguish this reset
157	 * from the normal (full) reset. bootcode.bin will not reboot after a
158	 * hard reset.
159	 */
160	val = readl_relaxed(wdt->base + PM_RSTS);
161	val |= PM_PASSWORD | PM_RSTS_RASPBERRYPI_HALT;
162	writel_relaxed(val, wdt->base + PM_RSTS);
163
164	/* Continue with normal reset mechanism */
165	bcm2835_restart(&wdt->restart_handler, REBOOT_HARD, NULL);
166}
167
168static int bcm2835_wdt_probe(struct platform_device *pdev)
169{
170	struct device *dev = &pdev->dev;
171	struct device_node *np = dev->of_node;
172	struct bcm2835_wdt *wdt;
173	int err;
174
175	wdt = devm_kzalloc(dev, sizeof(struct bcm2835_wdt), GFP_KERNEL);
176	if (!wdt)
177		return -ENOMEM;
178	platform_set_drvdata(pdev, wdt);
179
180	spin_lock_init(&wdt->lock);
181
182	wdt->base = of_iomap(np, 0);
183	if (!wdt->base) {
184		dev_err(dev, "Failed to remap watchdog regs");
185		return -ENODEV;
186	}
187
188	watchdog_set_drvdata(&bcm2835_wdt_wdd, wdt);
189	watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev);
190	watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout);
191	bcm2835_wdt_wdd.parent = &pdev->dev;
192	err = watchdog_register_device(&bcm2835_wdt_wdd);
193	if (err) {
194		dev_err(dev, "Failed to register watchdog device");
195		iounmap(wdt->base);
196		return err;
197	}
198
199	wdt->restart_handler.notifier_call = bcm2835_restart;
200	wdt->restart_handler.priority = 128;
201	register_restart_handler(&wdt->restart_handler);
202	if (pm_power_off == NULL)
203		pm_power_off = bcm2835_power_off;
204
205	dev_info(dev, "Broadcom BCM2835 watchdog timer");
206	return 0;
207}
208
209static int bcm2835_wdt_remove(struct platform_device *pdev)
210{
211	struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
212
213	unregister_restart_handler(&wdt->restart_handler);
214	if (pm_power_off == bcm2835_power_off)
215		pm_power_off = NULL;
216	watchdog_unregister_device(&bcm2835_wdt_wdd);
217	iounmap(wdt->base);
218
219	return 0;
220}
221
222static void bcm2835_wdt_shutdown(struct platform_device *pdev)
223{
224	bcm2835_wdt_stop(&bcm2835_wdt_wdd);
225}
226
227static const struct of_device_id bcm2835_wdt_of_match[] = {
228	{ .compatible = "brcm,bcm2835-pm-wdt", },
229	{},
230};
231MODULE_DEVICE_TABLE(of, bcm2835_wdt_of_match);
232
233static struct platform_driver bcm2835_wdt_driver = {
234	.probe		= bcm2835_wdt_probe,
235	.remove		= bcm2835_wdt_remove,
236	.shutdown	= bcm2835_wdt_shutdown,
237	.driver = {
238		.name =		"bcm2835-wdt",
239		.of_match_table = bcm2835_wdt_of_match,
240	},
241};
242module_platform_driver(bcm2835_wdt_driver);
243
244module_param(heartbeat, uint, 0);
245MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds");
246
247module_param(nowayout, bool, 0);
248MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
249				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
250
251MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
252MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer");
253MODULE_LICENSE("GPL");
254