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/types.h>
 17#include <linux/module.h>
 18#include <linux/io.h>
 19#include <linux/watchdog.h>
 20#include <linux/platform_device.h>
 21#include <linux/of_address.h>
 22
 23#define PM_RSTC				0x1c
 24#define PM_WDOG				0x24
 25
 26#define PM_PASSWORD			0x5a000000
 27
 28#define PM_WDOG_TIME_SET		0x000fffff
 29#define PM_RSTC_WRCFG_CLR		0xffffffcf
 30#define PM_RSTC_WRCFG_SET		0x00000030
 31#define PM_RSTC_WRCFG_FULL_RESET	0x00000020
 32#define PM_RSTC_RESET			0x00000102
 33
 34#define SECS_TO_WDOG_TICKS(x) ((x) << 16)
 35#define WDOG_TICKS_TO_SECS(x) ((x) >> 16)
 36
 37struct bcm2835_wdt {
 38	void __iomem		*base;
 39	spinlock_t		lock;
 40};
 41
 42static unsigned int heartbeat;
 43static bool nowayout = WATCHDOG_NOWAYOUT;
 44
 45static int bcm2835_wdt_start(struct watchdog_device *wdog)
 46{
 47	struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
 48	uint32_t cur;
 49	unsigned long flags;
 50
 51	spin_lock_irqsave(&wdt->lock, flags);
 52
 53	writel_relaxed(PM_PASSWORD | (SECS_TO_WDOG_TICKS(wdog->timeout) &
 54				PM_WDOG_TIME_SET), wdt->base + PM_WDOG);
 55	cur = readl_relaxed(wdt->base + PM_RSTC);
 56	writel_relaxed(PM_PASSWORD | (cur & PM_RSTC_WRCFG_CLR) |
 57		  PM_RSTC_WRCFG_FULL_RESET, wdt->base + PM_RSTC);
 58
 59	spin_unlock_irqrestore(&wdt->lock, flags);
 60
 61	return 0;
 62}
 63
 64static int bcm2835_wdt_stop(struct watchdog_device *wdog)
 65{
 66	struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
 67
 68	writel_relaxed(PM_PASSWORD | PM_RSTC_RESET, wdt->base + PM_RSTC);
 69	dev_info(wdog->dev, "Watchdog timer stopped");
 70	return 0;
 71}
 72
 73static int bcm2835_wdt_set_timeout(struct watchdog_device *wdog, unsigned int t)
 74{
 75	wdog->timeout = t;
 76	return 0;
 77}
 78
 79static unsigned int bcm2835_wdt_get_timeleft(struct watchdog_device *wdog)
 80{
 81	struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
 82
 83	uint32_t ret = readl_relaxed(wdt->base + PM_WDOG);
 84	return WDOG_TICKS_TO_SECS(ret & PM_WDOG_TIME_SET);
 85}
 86
 87static struct watchdog_ops bcm2835_wdt_ops = {
 88	.owner =	THIS_MODULE,
 89	.start =	bcm2835_wdt_start,
 90	.stop =		bcm2835_wdt_stop,
 91	.set_timeout =	bcm2835_wdt_set_timeout,
 92	.get_timeleft =	bcm2835_wdt_get_timeleft,
 93};
 94
 95static struct watchdog_info bcm2835_wdt_info = {
 96	.options =	WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
 97			WDIOF_KEEPALIVEPING,
 98	.identity =	"Broadcom BCM2835 Watchdog timer",
 99};
100
101static struct watchdog_device bcm2835_wdt_wdd = {
102	.info =		&bcm2835_wdt_info,
103	.ops =		&bcm2835_wdt_ops,
104	.min_timeout =	1,
105	.max_timeout =	WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
106	.timeout =	WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
107};
108
109static int bcm2835_wdt_probe(struct platform_device *pdev)
110{
111	struct device *dev = &pdev->dev;
112	struct device_node *np = dev->of_node;
113	struct bcm2835_wdt *wdt;
114	int err;
115
116	wdt = devm_kzalloc(dev, sizeof(struct bcm2835_wdt), GFP_KERNEL);
117	if (!wdt)
118		return -ENOMEM;
119	platform_set_drvdata(pdev, wdt);
120
121	spin_lock_init(&wdt->lock);
122
123	wdt->base = of_iomap(np, 0);
124	if (!wdt->base) {
125		dev_err(dev, "Failed to remap watchdog regs");
126		return -ENODEV;
127	}
128
129	watchdog_set_drvdata(&bcm2835_wdt_wdd, wdt);
130	watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev);
131	watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout);
132	err = watchdog_register_device(&bcm2835_wdt_wdd);
133	if (err) {
134		dev_err(dev, "Failed to register watchdog device");
135		iounmap(wdt->base);
136		return err;
137	}
138
139	dev_info(dev, "Broadcom BCM2835 watchdog timer");
140	return 0;
141}
142
143static int bcm2835_wdt_remove(struct platform_device *pdev)
144{
145	struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
146
147	watchdog_unregister_device(&bcm2835_wdt_wdd);
148	iounmap(wdt->base);
149
150	return 0;
151}
152
153static void bcm2835_wdt_shutdown(struct platform_device *pdev)
154{
155	bcm2835_wdt_stop(&bcm2835_wdt_wdd);
156}
157
158static const struct of_device_id bcm2835_wdt_of_match[] = {
159	{ .compatible = "brcm,bcm2835-pm-wdt", },
160	{},
161};
162MODULE_DEVICE_TABLE(of, bcm2835_wdt_of_match);
163
164static struct platform_driver bcm2835_wdt_driver = {
165	.probe		= bcm2835_wdt_probe,
166	.remove		= bcm2835_wdt_remove,
167	.shutdown	= bcm2835_wdt_shutdown,
168	.driver = {
169		.name =		"bcm2835-wdt",
170		.owner =	THIS_MODULE,
171		.of_match_table = bcm2835_wdt_of_match,
172	},
173};
174module_platform_driver(bcm2835_wdt_driver);
175
176module_param(heartbeat, uint, 0);
177MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds");
178
179module_param(nowayout, bool, 0);
180MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
181				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
182
183MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
184MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer");
185MODULE_LICENSE("GPL");