OpenCellular/chip/npcx/watchdog.c

/* Copyright (c) 2014 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 driver */

#include "clock.h"
#include "common.h"
#include "console.h"
#include "registers.h"
#include "hwtimer_chip.h"
#include "gpio.h"
#include "hooks.h"
#include "timer.h"
#include "task.h"
#include "util.h"
#include "system_chip.h"
#include "watchdog.h"

/* WDCNT value for watchdog period */
#define WDCNT_VALUE   ((CONFIG_WATCHDOG_PERIOD_MS*INT_32K_CLOCK) / (1024*1000))
/* Delay time for warning timer to print watchdog info through UART */
#define WDCNT_DELAY   WDCNT_VALUE

void watchdog_init_warning_timer(void)
{
	/* init watchdog timer first */
	init_hw_timer(ITIM_WDG_NO, ITIM_SOURCE_CLOCK_32K);

	/*
	 * prescaler to TIMER_TICK
	 * Ttick_unit = (PRE_8+1) * T32k
	 * PRE_8 = (Ttick_unit/T32K) - 1
	 * Unit: 1 msec
	 */
	NPCX_ITPRE(ITIM_WDG_NO)  = DIV_ROUND_NEAREST(1000*INT_32K_CLOCK,
							 SECOND) - 1;

	/* ITIM count down : event expired*/
	NPCX_ITCNT16(ITIM_WDG_NO) = CONFIG_AUX_TIMER_PERIOD_MS - 1;
	/* Event module enable */
	SET_BIT(NPCX_ITCTS(ITIM_WDG_NO), NPCX_ITCTS_ITEN);
	/* Enable interrupt of ITIM */
	task_enable_irq(ITIM16_INT(ITIM_WDG_NO));
}

static uint8_t watchdog_count(void)
{
	uint8_t cnt;
	/* Wait for two consecutive equal values are read */
	do {
		cnt = NPCX_TWMWD;
	} while (cnt != NPCX_TWMWD);

	return cnt;
}

void __keep watchdog_check(uint32_t excep_lr, uint32_t excep_sp)
{
	int  wd_cnt;

	/* Clear timeout status for event */
	SET_BIT(NPCX_ITCTS(ITIM_WDG_NO), NPCX_ITCTS_TO_STS);

	/* Read watchdog counter from TWMWD */
	wd_cnt = watchdog_count();
#if DEBUG_WDG
	panic_printf("WD (%d)\r\n", wd_cnt);
#endif
	if (wd_cnt <= WDCNT_DELAY) {
		/*
		 * Touch watchdog to let UART have enough time
		 * to print panic info
		 */
		NPCX_WDSDM = 0x5C;
		/* Print panic info */
		watchdog_trace(excep_lr, excep_sp);
		cflush();

		/* Trigger watchdog immediately */
		system_watchdog_reset();
	}
}

/* ISR for watchdog warning naked will keep SP & LR */
void IRQ_HANDLER(ITIM16_INT(ITIM_WDG_NO))(void) __attribute__((naked));
void IRQ_HANDLER(ITIM16_INT(ITIM_WDG_NO))(void)
{
	/* Naked call so we can extract raw LR and SP */
	asm volatile("mov r0, lr\n"
			"mov r1, sp\n"
			/* Must push registers in pairs to keep 64-bit aligned
			 * stack for ARM EABI.  This also conveninently saves
			 * R0=LR so we can pass it to task_resched_if_needed. */
			"push {r0, lr}\n"
			"bl watchdog_check\n"
			"pop {r0, lr}\n"
			"b task_resched_if_needed\n");
}
const struct irq_priority __keep IRQ_PRIORITY(ITIM16_INT(ITIM_WDG_NO))
__attribute__((section(".rodata.irqprio")))
= {ITIM16_INT(ITIM_WDG_NO), 0};
/* put the watchdog at the highest priority */

void watchdog_reload(void)
{
	/* Disable watchdog interrupt */
	task_disable_irq(ITIM16_INT(ITIM_WDG_NO));

#if 1 /* mark this for testing watchdog */
	/* Touch watchdog & reset software counter */
	NPCX_WDSDM = 0x5C;
#endif

	/* Enable watchdog interrupt */
	task_enable_irq(ITIM16_INT(ITIM_WDG_NO));
}
DECLARE_HOOK(HOOK_TICK, watchdog_reload, HOOK_PRIO_DEFAULT);

int watchdog_init(void)
{
#if SUPPORT_WDG
	/* Keep prescaler ratio timer0 clock to 1:1024 */
	NPCX_TWCP = 0x0A;
	/* Keep prescaler ratio watchdog clock to 1:1 */
	NPCX_WDCP = 0;

	/* Clear watchdog reset status initially*/
	SET_BIT(NPCX_T0CSR, NPCX_T0CSR_WDRST_STS);

	/* Reset TWCFG */
	NPCX_TWCFG = 0;
	/* Watchdog touch by writing 5Ch to WDSDM */
	SET_BIT(NPCX_TWCFG, NPCX_TWCFG_WDSDME);
	/* Select T0IN clock as watchdog prescaler clock */
	SET_BIT(NPCX_TWCFG, NPCX_TWCFG_WDCT0I);
	/* Disable early touch functionality */
	SET_BIT(NPCX_T0CSR, NPCX_T0CSR_TESDIS);

	/*
	 * Set WDCNT initial reload value and T0OUT timeout period
	 * 1. Watchdog clock source is 32768/1024 Hz and disable T0OUT.
	 * 2. ITIM16 will be issued to check WDCNT is under WDCNT_DELAY or not
	 * 3. Set RST to upload TWDT0 & WDCNT
	 */
	/* Set WDCNT --> WDCNT=0 will generate watchdog reset */
	NPCX_WDCNT = WDCNT_VALUE + WDCNT_DELAY;

	/* Disable interrupt */
	interrupt_disable();
	/* Reload TWDT0/WDCNT */
	SET_BIT(NPCX_T0CSR, NPCX_T0CSR_RST);
	/* Wait for timer is loaded and restart */
	while (IS_BIT_SET(NPCX_T0CSR, NPCX_T0CSR_RST))
		;
	/* Enable interrupt */
	interrupt_enable();

	/* Init watchdog warning timer */
	watchdog_init_warning_timer();
#endif
	return EC_SUCCESS;
}