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

   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
  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         {},
  66 };
  67
  68 void __init samsung_wdt_reset_of_init(void)
  69 {
  70         struct device_node *np;
  71
  72         np = of_find_matching_node(NULL, s3c2410_wdt_match);
  73         if (!np) {
  74                 pr_err("%s: failed to find watchdog node\n", __func__);
  75                 return;
  76         }
  77
  78         wdt_base = of_iomap(np, 0);
  79         if (!wdt_base) {
  80                 pr_err("%s: failed to map watchdog registers\n", __func__);
  81                 return;
  82         }
  83
  84         wdt_clock = of_clk_get(np, 0);
  85 }
  86 #endif
  87
  88 void __init samsung_wdt_reset_init(void __iomem *base)
  89 {
  90         wdt_base = base;
  91         wdt_clock = clk_get(NULL, "watchdog");
  92 }