summaryrefslogtreecommitdiff
path: root/drivers/watchdog/bcm7038_wdt.c
blob: 979caa18d3c88f5393a66d39cca7f6e6db98b1c9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright (C) 2015 Broadcom Corporation
 *
 */

#include <linux/clk.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pm.h>
#include <linux/watchdog.h>

#define WDT_START_1		0xff00
#define WDT_START_2		0x00ff
#define WDT_STOP_1		0xee00
#define WDT_STOP_2		0x00ee

#define WDT_TIMEOUT_REG		0x0
#define WDT_CMD_REG		0x4

#define WDT_MIN_TIMEOUT		1 /* seconds */
#define WDT_DEFAULT_TIMEOUT	30 /* seconds */
#define WDT_DEFAULT_RATE	27000000

struct bcm7038_watchdog {
	void __iomem		*base;
	struct watchdog_device	wdd;
	u32			rate;
	struct clk		*clk;
};

static bool nowayout = WATCHDOG_NOWAYOUT;

static void bcm7038_wdt_set_timeout_reg(struct watchdog_device *wdog)
{
	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
	u32 timeout;

	timeout = wdt->rate * wdog->timeout;

	writel(timeout, wdt->base + WDT_TIMEOUT_REG);
}

static int bcm7038_wdt_ping(struct watchdog_device *wdog)
{
	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);

	writel(WDT_START_1, wdt->base + WDT_CMD_REG);
	writel(WDT_START_2, wdt->base + WDT_CMD_REG);

	return 0;
}

static int bcm7038_wdt_start(struct watchdog_device *wdog)
{
	bcm7038_wdt_set_timeout_reg(wdog);
	bcm7038_wdt_ping(wdog);

	return 0;
}

static int bcm7038_wdt_stop(struct watchdog_device *wdog)
{
	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);

	writel(WDT_STOP_1, wdt->base + WDT_CMD_REG);
	writel(WDT_STOP_2, wdt->base + WDT_CMD_REG);

	return 0;
}

static int bcm7038_wdt_set_timeout(struct watchdog_device *wdog,
				   unsigned int t)
{
	/* Can't modify timeout value if watchdog timer is running */
	bcm7038_wdt_stop(wdog);
	wdog->timeout = t;
	bcm7038_wdt_start(wdog);

	return 0;
}

static unsigned int bcm7038_wdt_get_timeleft(struct watchdog_device *wdog)
{
	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
	u32 time_left;

	time_left = readl(wdt->base + WDT_CMD_REG);

	return time_left / wdt->rate;
}

static const struct watchdog_info bcm7038_wdt_info = {
	.identity	= "Broadcom BCM7038 Watchdog Timer",
	.options	= WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
				WDIOF_MAGICCLOSE
};

static const struct watchdog_ops bcm7038_wdt_ops = {
	.owner		= THIS_MODULE,
	.start		= bcm7038_wdt_start,
	.stop		= bcm7038_wdt_stop,
	.set_timeout	= bcm7038_wdt_set_timeout,
	.get_timeleft	= bcm7038_wdt_get_timeleft,
};

static void bcm7038_clk_disable_unprepare(void *data)
{
	clk_disable_unprepare(data);
}

static int bcm7038_wdt_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct bcm7038_watchdog *wdt;
	int err;

	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
	if (!wdt)
		return -ENOMEM;

	platform_set_drvdata(pdev, wdt);

	wdt->base = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(wdt->base))
		return PTR_ERR(wdt->base);

	wdt->clk = devm_clk_get(dev, NULL);
	/* If unable to get clock, use default frequency */
	if (!IS_ERR(wdt->clk)) {
		err = clk_prepare_enable(wdt->clk);
		if (err)
			return err;
		err = devm_add_action_or_reset(dev,
					       bcm7038_clk_disable_unprepare,
					       wdt->clk);
		if (err)
			return err;
		wdt->rate = clk_get_rate(wdt->clk);
		/* Prevent divide-by-zero exception */
		if (!wdt->rate)
			wdt->rate = WDT_DEFAULT_RATE;
	} else {
		wdt->rate = WDT_DEFAULT_RATE;
		wdt->clk = NULL;
	}

	wdt->wdd.info		= &bcm7038_wdt_info;
	wdt->wdd.ops		= &bcm7038_wdt_ops;
	wdt->wdd.min_timeout	= WDT_MIN_TIMEOUT;
	wdt->wdd.timeout	= WDT_DEFAULT_TIMEOUT;
	wdt->wdd.max_timeout	= 0xffffffff / wdt->rate;
	wdt->wdd.parent		= dev;
	watchdog_set_drvdata(&wdt->wdd, wdt);

	watchdog_stop_on_reboot(&wdt->wdd);
	watchdog_stop_on_unregister(&wdt->wdd);
	err = devm_watchdog_register_device(dev, &wdt->wdd);
	if (err)
		return err;

	dev_info(dev, "Registered BCM7038 Watchdog\n");

	return 0;
}

#ifdef CONFIG_PM_SLEEP
static int bcm7038_wdt_suspend(struct device *dev)
{
	struct bcm7038_watchdog *wdt = dev_get_drvdata(dev);

	if (watchdog_active(&wdt->wdd))
		return bcm7038_wdt_stop(&wdt->wdd);

	return 0;
}

static int bcm7038_wdt_resume(struct device *dev)
{
	struct bcm7038_watchdog *wdt = dev_get_drvdata(dev);

	if (watchdog_active(&wdt->wdd))
		return bcm7038_wdt_start(&wdt->wdd);

	return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(bcm7038_wdt_pm_ops, bcm7038_wdt_suspend,
			 bcm7038_wdt_resume);

static const struct of_device_id bcm7038_wdt_match[] = {
	{ .compatible = "brcm,bcm7038-wdt" },
	{},
};
MODULE_DEVICE_TABLE(of, bcm7038_wdt_match);

static struct platform_driver bcm7038_wdt_driver = {
	.probe		= bcm7038_wdt_probe,
	.driver		= {
		.name		= "bcm7038-wdt",
		.of_match_table	= bcm7038_wdt_match,
		.pm		= &bcm7038_wdt_pm_ops,
	}
};
module_platform_driver(bcm7038_wdt_driver);

module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Driver for Broadcom 7038 SoCs Watchdog");
MODULE_AUTHOR("Justin Chen");