1 // SPDX-License-Identifier: GPL-2.0
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 #include <linux/clk.h>
11 #include <linux/err.h>
12 #include <linux/io.h>
13 #include <linux/delay.h>
14 #include <linux/of.h>
15 #include <linux/of_address.h>
16
17 #define S3C2410_WTCON 0x00
18 #define S3C2410_WTDAT 0x04
19 #define S3C2410_WTCNT 0x08
20
21 #define S3C2410_WTCON_ENABLE (1 << 5)
22 #define S3C2410_WTCON_DIV16 (0 << 3)
23 #define S3C2410_WTCON_RSTEN (1 << 0)
24 #define S3C2410_WTCON_PRESCALE(x) ((x) << 8)
25
26 static void __iomem *wdt_base;
27 static struct clk *wdt_clock;
28
samsung_wdt_reset(void)29 void samsung_wdt_reset(void)
30 {
31 if (!wdt_base) {
32 pr_err("%s: wdt reset not initialized\n", __func__);
33 /* delay to allow the serial port to show the message */
34 mdelay(50);
35 return;
36 }
37
38 if (!IS_ERR(wdt_clock))
39 clk_prepare_enable(wdt_clock);
40
41 /* disable watchdog, to be safe */
42 __raw_writel(0, wdt_base + S3C2410_WTCON);
43
44 /* put initial values into count and data */
45 __raw_writel(0x80, wdt_base + S3C2410_WTCNT);
46 __raw_writel(0x80, wdt_base + S3C2410_WTDAT);
47
48 /* set the watchdog to go and reset... */
49 __raw_writel(S3C2410_WTCON_ENABLE | S3C2410_WTCON_DIV16 |
50 S3C2410_WTCON_RSTEN | S3C2410_WTCON_PRESCALE(0x20),
51 wdt_base + S3C2410_WTCON);
52
53 /* wait for reset to assert... */
54 mdelay(500);
55
56 pr_err("Watchdog reset failed to assert reset\n");
57
58 /* delay to allow the serial port to show the message */
59 mdelay(50);
60 }
61
62 #ifdef CONFIG_OF
63 static const struct of_device_id s3c2410_wdt_match[] = {
64 { .compatible = "samsung,s3c2410-wdt" },
65 { .compatible = "samsung,s3c6410-wdt" },
66 {},
67 };
68
samsung_wdt_reset_of_init(void)69 void __init samsung_wdt_reset_of_init(void)
70 {
71 struct device_node *np;
72
73 np = of_find_matching_node(NULL, s3c2410_wdt_match);
74 if (!np) {
75 pr_err("%s: failed to find watchdog node\n", __func__);
76 return;
77 }
78
79 wdt_base = of_iomap(np, 0);
80 if (!wdt_base) {
81 pr_err("%s: failed to map watchdog registers\n", __func__);
82 return;
83 }
84
85 wdt_clock = of_clk_get(np, 0);
86 }
87 #endif
88
samsung_wdt_reset_init(void __iomem * base)89 void __init samsung_wdt_reset_init(void __iomem *base)
90 {
91 wdt_base = base;
92 wdt_clock = clk_get(NULL, "watchdog");
93 }
94