1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Watchdog driver for Broadcom BCM2835
4 *
5 * "bcm2708_wdog" driver written by Luke Diamand that was obtained from
6 * branch "rpi-3.6.y" of git://github.com/raspberrypi/linux.git was used
7 * as a hardware reference for the Broadcom BCM2835 watchdog timer.
8 *
9 * Copyright (C) 2013 Lubomir Rintel <lkundrak@v3.sk>
10 *
11 */
12
13#include <linux/delay.h>
14#include <linux/types.h>
15#include <linux/mfd/bcm2835-pm.h>
16#include <linux/module.h>
17#include <linux/io.h>
18#include <linux/watchdog.h>
19#include <linux/platform_device.h>
20#include <linux/of_address.h>
21#include <linux/of_platform.h>
22
23#define PM_RSTC				0x1c
24#define PM_RSTS				0x20
25#define PM_WDOG				0x24
26
27#define PM_PASSWORD			0x5a000000
28
29#define PM_WDOG_TIME_SET		0x000fffff
30#define PM_RSTC_WRCFG_CLR		0xffffffcf
31#define PM_RSTS_HADWRH_SET		0x00000040
32#define PM_RSTC_WRCFG_SET		0x00000030
33#define PM_RSTC_WRCFG_FULL_RESET	0x00000020
34#define PM_RSTC_RESET			0x00000102
35
36/*
37 * The Raspberry Pi firmware uses the RSTS register to know which partition
38 * to boot from. The partition value is spread into bits 0, 2, 4, 6, 8, 10.
39 * Partition 63 is a special partition used by the firmware to indicate halt.
40 */
41#define PM_RSTS_RASPBERRYPI_HALT	0x555
42
43#define SECS_TO_WDOG_TICKS(x) ((x) << 16)
44#define WDOG_TICKS_TO_SECS(x) ((x) >> 16)
45#define WDOG_TICKS_TO_MSECS(x) ((x) * 1000 >> 16)
46
47struct bcm2835_wdt {
48	void __iomem		*base;
49	spinlock_t		lock;
50};
51
52static struct bcm2835_wdt *bcm2835_power_off_wdt;
53
54static unsigned int heartbeat;
55static bool nowayout = WATCHDOG_NOWAYOUT;
56
57static bool bcm2835_wdt_is_running(struct bcm2835_wdt *wdt)
58{
59	uint32_t cur;
60
61	cur = readl(wdt->base + PM_RSTC);
62
63	return !!(cur & PM_RSTC_WRCFG_FULL_RESET);
64}
65
66static int bcm2835_wdt_start(struct watchdog_device *wdog)
67{
68	struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
69	uint32_t cur;
70	unsigned long flags;
71
72	spin_lock_irqsave(&wdt->lock, flags);
73
74	writel_relaxed(PM_PASSWORD | (SECS_TO_WDOG_TICKS(wdog->timeout) &
75				PM_WDOG_TIME_SET), wdt->base + PM_WDOG);
76	cur = readl_relaxed(wdt->base + PM_RSTC);
77	writel_relaxed(PM_PASSWORD | (cur & PM_RSTC_WRCFG_CLR) |
78		  PM_RSTC_WRCFG_FULL_RESET, wdt->base + PM_RSTC);
79
80	spin_unlock_irqrestore(&wdt->lock, flags);
81
82	return 0;
83}
84
85static int bcm2835_wdt_stop(struct watchdog_device *wdog)
86{
87	struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
88
89	writel_relaxed(PM_PASSWORD | PM_RSTC_RESET, wdt->base + PM_RSTC);
90	return 0;
91}
92
93static unsigned int bcm2835_wdt_get_timeleft(struct watchdog_device *wdog)
94{
95	struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
96
97	uint32_t ret = readl_relaxed(wdt->base + PM_WDOG);
98	return WDOG_TICKS_TO_SECS(ret & PM_WDOG_TIME_SET);
99}
100
101static void __bcm2835_restart(struct bcm2835_wdt *wdt)
102{
103	u32 val;
104
105	/* use a timeout of 10 ticks (~150us) */
106	writel_relaxed(10 | PM_PASSWORD, wdt->base + PM_WDOG);
107	val = readl_relaxed(wdt->base + PM_RSTC);
108	val &= PM_RSTC_WRCFG_CLR;
109	val |= PM_PASSWORD | PM_RSTC_WRCFG_FULL_RESET;
110	writel_relaxed(val, wdt->base + PM_RSTC);
111
112	/* No sleeping, possibly atomic. */
113	mdelay(1);
114}
115
116static int bcm2835_restart(struct watchdog_device *wdog,
117			   unsigned long action, void *data)
118{
119	struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
120
121	__bcm2835_restart(wdt);
122
123	return 0;
124}
125
126static const struct watchdog_ops bcm2835_wdt_ops = {
127	.owner =	THIS_MODULE,
128	.start =	bcm2835_wdt_start,
129	.stop =		bcm2835_wdt_stop,
130	.get_timeleft =	bcm2835_wdt_get_timeleft,
131	.restart =	bcm2835_restart,
132};
133
134static const struct watchdog_info bcm2835_wdt_info = {
135	.options =	WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
136			WDIOF_KEEPALIVEPING,
137	.identity =	"Broadcom BCM2835 Watchdog timer",
138};
139
140static struct watchdog_device bcm2835_wdt_wdd = {
141	.info =		&bcm2835_wdt_info,
142	.ops =		&bcm2835_wdt_ops,
143	.min_timeout =	1,
144	.max_hw_heartbeat_ms =	WDOG_TICKS_TO_MSECS(PM_WDOG_TIME_SET),
145	.timeout =	WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
146};
147
148/*
149 * We can't really power off, but if we do the normal reset scheme, and
150 * indicate to bootcode.bin not to reboot, then most of the chip will be
151 * powered off.
152 */
153static void bcm2835_power_off(void)
154{
155	struct bcm2835_wdt *wdt = bcm2835_power_off_wdt;
156	u32 val;
157
158	/*
159	 * We set the watchdog hard reset bit here to distinguish this reset
160	 * from the normal (full) reset. bootcode.bin will not reboot after a
161	 * hard reset.
162	 */
163	val = readl_relaxed(wdt->base + PM_RSTS);
164	val |= PM_PASSWORD | PM_RSTS_RASPBERRYPI_HALT;
165	writel_relaxed(val, wdt->base + PM_RSTS);
166
167	/* Continue with normal reset mechanism */
168	__bcm2835_restart(wdt);
169}
170
171static int bcm2835_wdt_probe(struct platform_device *pdev)
172{
173	struct bcm2835_pm *pm = dev_get_drvdata(pdev->dev.parent);
174	struct device *dev = &pdev->dev;
175	struct bcm2835_wdt *wdt;
176	int err;
177
178	wdt = devm_kzalloc(dev, sizeof(struct bcm2835_wdt), GFP_KERNEL);
179	if (!wdt)
180		return -ENOMEM;
181
182	spin_lock_init(&wdt->lock);
183
184	wdt->base = pm->base;
185
186	watchdog_set_drvdata(&bcm2835_wdt_wdd, wdt);
187	watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev);
188	watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout);
189	bcm2835_wdt_wdd.parent = dev;
190	if (bcm2835_wdt_is_running(wdt)) {
191		/*
192		 * The currently active timeout value (set by the
193		 * bootloader) may be different from the module
194		 * heartbeat parameter or the value in device
195		 * tree. But we just need to set WDOG_HW_RUNNING,
196		 * because then the framework will "immediately" ping
197		 * the device, updating the timeout.
198		 */
199		set_bit(WDOG_HW_RUNNING, &bcm2835_wdt_wdd.status);
200	}
201
202	watchdog_set_restart_priority(&bcm2835_wdt_wdd, 128);
203
204	watchdog_stop_on_reboot(&bcm2835_wdt_wdd);
205	err = devm_watchdog_register_device(dev, &bcm2835_wdt_wdd);
206	if (err)
207		return err;
208
209	if (of_device_is_system_power_controller(pdev->dev.parent->of_node)) {
210		if (!pm_power_off) {
211			pm_power_off = bcm2835_power_off;
212			bcm2835_power_off_wdt = wdt;
213		} else {
214			dev_info(dev, "Poweroff handler already present!\n");
215		}
216	}
217
218	dev_info(dev, "Broadcom BCM2835 watchdog timer");
219	return 0;
220}
221
222static void bcm2835_wdt_remove(struct platform_device *pdev)
223{
224	if (pm_power_off == bcm2835_power_off)
225		pm_power_off = NULL;
226}
227
228static struct platform_driver bcm2835_wdt_driver = {
229	.probe		= bcm2835_wdt_probe,
230	.remove_new	= bcm2835_wdt_remove,
231	.driver = {
232		.name =		"bcm2835-wdt",
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_ALIAS("platform:bcm2835-wdt");
245MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
246MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer");
247MODULE_LICENSE("GPL");
248