1/* arch/arm/plat-samsung/watchdog-reset.c
2 *
3 * Copyright (c) 2008 Simtec Electronics
4 *	Ben Dooks <ben@simtec.co.uk>
5 *
6 * Coyright (c) 2013 Tomasz Figa <tomasz.figa@gmail.com>
7 *
8 * Watchdog reset support for Samsung SoCs.
9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License version 2 as
12 * published by the Free Software Foundation.
13*/
14
15#include <linux/clk.h>
16#include <linux/err.h>
17#include <linux/io.h>
18#include <linux/delay.h>
19#include <linux/of.h>
20#include <linux/of_address.h>
21
22#define S3C2410_WTCON			0x00
23#define S3C2410_WTDAT			0x04
24#define S3C2410_WTCNT			0x08
25
26#define S3C2410_WTCON_ENABLE		(1 << 5)
27#define S3C2410_WTCON_DIV16		(0 << 3)
28#define S3C2410_WTCON_RSTEN		(1 << 0)
29#define S3C2410_WTCON_PRESCALE(x)	((x) << 8)
30
31static void __iomem *wdt_base;
32static struct clk *wdt_clock;
33
34void samsung_wdt_reset(void)
35{
36	if (!wdt_base) {
37		pr_err("%s: wdt reset not initialized\n", __func__);
38		/* delay to allow the serial port to show the message */
39		mdelay(50);
40		return;
41	}
42
43	if (!IS_ERR(wdt_clock))
44		clk_prepare_enable(wdt_clock);
45
46	/* disable watchdog, to be safe  */
47	__raw_writel(0, wdt_base + S3C2410_WTCON);
48
49	/* put initial values into count and data */
50	__raw_writel(0x80, wdt_base + S3C2410_WTCNT);
51	__raw_writel(0x80, wdt_base + S3C2410_WTDAT);
52
53	/* set the watchdog to go and reset... */
54	__raw_writel(S3C2410_WTCON_ENABLE | S3C2410_WTCON_DIV16 |
55			S3C2410_WTCON_RSTEN | S3C2410_WTCON_PRESCALE(0x20),
56			wdt_base + S3C2410_WTCON);
57
58	/* wait for reset to assert... */
59	mdelay(500);
60
61	pr_err("Watchdog reset failed to assert reset\n");
62
63	/* delay to allow the serial port to show the message */
64	mdelay(50);
65}
66
67#ifdef CONFIG_OF
68static const struct of_device_id s3c2410_wdt_match[] = {
69	{ .compatible = "samsung,s3c2410-wdt" },
70	{},
71};
72
73void __init samsung_wdt_reset_of_init(void)
74{
75	struct device_node *np;
76
77	np = of_find_matching_node(NULL, s3c2410_wdt_match);
78	if (!np) {
79		pr_err("%s: failed to find watchdog node\n", __func__);
80		return;
81	}
82
83	wdt_base = of_iomap(np, 0);
84	if (!wdt_base) {
85		pr_err("%s: failed to map watchdog registers\n", __func__);
86		return;
87	}
88
89	wdt_clock = of_clk_get(np, 0);
90}
91#endif
92
93void __init samsung_wdt_reset_init(void __iomem *base)
94{
95	wdt_base = base;
96	wdt_clock = clk_get(NULL, "watchdog");
97}
98