arch/arm/mach-omap2/wd_timer.c

   1 /*
   2  * OMAP2+ MPU WD_TIMER-specific code
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  */
   9
  10 #include <linux/kernel.h>
  11 #include <linux/io.h>
  12 #include <linux/err.h>
  13
  14 #include <plat/omap_hwmod.h>
  15
  16 #include "wd_timer.h"
  17
  18 /*
  19  * In order to avoid any assumptions from bootloader regarding WDT
  20  * settings, WDT module is reset during init. This enables the watchdog
  21  * timer. Hence it is required to disable the watchdog after the WDT reset
  22  * during init. Otherwise the system would reboot as per the default
  23  * watchdog timer registers settings.
  24  */
  25 #define OMAP_WDT_WPS            0x34
  26 #define OMAP_WDT_SPR            0x48
  27
  28
  29 int omap2_wd_timer_disable(struct omap_hwmod *oh)
  30 {
  31         void __iomem *base;
  32
  33         if (!oh) {
  34                 pr_err("%s: Could not look up wdtimer_hwmod\n", __func__);
  35                 return -EINVAL;
  36         }
  37
  38         base = omap_hwmod_get_mpu_rt_va(oh);
  39         if (!base) {
  40                 pr_err("%s: Could not get the base address for %s\n",
  41                                 oh->name, __func__);
  42                 return -EINVAL;
  43         }
  44
  45         /* sequence required to disable watchdog */
  46         __raw_writel(0xAAAA, base + OMAP_WDT_SPR);
  47         while (__raw_readl(base + OMAP_WDT_WPS) & 0x10)
  48                 cpu_relax();
  49
  50         __raw_writel(0x5555, base + OMAP_WDT_SPR);
  51         while (__raw_readl(base + OMAP_WDT_WPS) & 0x10)
  52                 cpu_relax();
  53
  54         return 0;
  55 }
  56