/* Copyright 2019 The Chromium OS Authors. All rights reserved. * Use of this source code is governed by a BSD-style license that can be * found in the LICENSE file. * * Watchdog Timer * * In ISH, there is a watchdog timer available from the hardware. It is * controlled by a few registers: * * - WDT_CONTROL (consists of enable bit, T1, and T2 values): When T1 * reaches 0, a warning is fired. After T2 then reaches 0, the system * will reset. * - WDT_RELOAD: Pet the watchdog by setting to 1 * - WDT_VALUES: Gives software access to T1 and T2 if needed * * For ISH implementation, we wish to reset only the ISH. Waiting until * T2 expires will kill the whole system. The functionality of T2 is * ignored, and we simply call system_reset when T1 expires. T2 will * only be used if the system cannot reset when T1 expires. */ #include "common.h" #include "ec_commands.h" #include "hooks.h" #include "ish_persistent_data.h" #include "task.h" #include "registers.h" #include "system.h" #include "watchdog.h" /* Units are hundreds of milliseconds */ #define WDT_T1_PERIOD (100) /* 10 seconds */ #define WDT_T2_PERIOD (10) /* 1 second */ int watchdog_init(void) { /* * Put reset counter back at zero if last reset was not caused * by watchdog */ if ((system_get_reset_flags() & EC_RESET_FLAG_WATCHDOG) == 0) ish_persistent_data.watchdog_counter = 0; /* Initialize WDT clock divider */ CCU_WDT_CD = WDT_CLOCK_HZ / 10; /* 10 Hz => 100 ms period */ /* Enable the watchdog timer and set initial T1/T2 values */ WDT_CONTROL = WDT_CONTROL_ENABLE_BIT | (WDT_T2_PERIOD << 8) | WDT_T1_PERIOD; task_enable_irq(ISH_WDT_IRQ); return EC_SUCCESS; } void watchdog_reload(void) { /* * ISH Supplemental Registers Info, 1.2.6.2: * "When firmware writes a 1 to this bit, hardware reloads * the values in WDT_T1 and WDT_T2..." */ WDT_RELOAD = 1; } DECLARE_HOOK(HOOK_TICK, watchdog_reload, HOOK_PRIO_DEFAULT);