arch/arm/plat-samsung/watchdog-reset.c

   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
  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         {},
  71 };
  72
  73 void __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
  93 void __init samsung_wdt_reset_init(void __iomem *base)
  94 {
  95         wdt_base = base;
  96         wdt_clock = clk_get(NULL, "watchdog");
  97 }