1 /* arch/arm/plat-samsung/watchdog-reset.c
2 *
3 * Copyright (c) 2008 Simtec Electronics
4 * Ben Dooks <ben@simtec.co.uk>
5 *
6 * Copyright (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
31 static void __iomem *wdt_base;
32 static struct clk *wdt_clock;
33
samsung_wdt_reset(void)34 void 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
68 static const struct of_device_id s3c2410_wdt_match[] = {
69 { .compatible = "samsung,s3c2410-wdt" },
70 { .compatible = "samsung,s3c6410-wdt" },
71 {},
72 };
73
samsung_wdt_reset_of_init(void)74 void __init samsung_wdt_reset_of_init(void)
75 {
76 struct device_node *np;
77
78 np = of_find_matching_node(NULL, s3c2410_wdt_match);
79 if (!np) {
80 pr_err("%s: failed to find watchdog node\n", __func__);
81 return;
82 }
83
84 wdt_base = of_iomap(np, 0);
85 if (!wdt_base) {
86 pr_err("%s: failed to map watchdog registers\n", __func__);
87 return;
88 }
89
90 wdt_clock = of_clk_get(np, 0);
91 }
92 #endif
93
samsung_wdt_reset_init(void __iomem * base)94 void __init samsung_wdt_reset_init(void __iomem *base)
95 {
96 wdt_base = base;
97 wdt_clock = clk_get(NULL, "watchdog");
98 }
99