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* ARM CMSDK APB watchdog emulation
* Copyright (c) 2018 Linaro Limited
* Written by Peter Maydell
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 or
* (at your option) any later version.
* This is a model of the "APB watchdog" which is part of the Cortex-M
* System Design Kit (CMSDK) and documented in the Cortex-M System
* Design Kit Technical Reference Manual (ARM DDI0479C):
* QEMU interface:
* + QOM property "wdogclk-frq": frequency at which the watchdog is clocked
* + sysbus MMIO region 0: the register bank
* + sysbus IRQ 0: watchdog interrupt
* In real hardware the watchdog's reset output is just a GPIO line
* which can then be masked by the board or treated as a simple interrupt.
* (For instance the IoTKit does this with the non-secure watchdog, so that
* secure code can control whether non-secure code can perform a system
* reset via its watchdog.) In QEMU, we just wire up the watchdog reset
* to watchdog_perform_action(), at least for the moment.
#include "hw/sysbus.h"
#include "hw/ptimer.h"
#define TYPE_CMSDK_APB_WATCHDOG "cmsdk-apb-watchdog"
typedef struct CMSDKAPBWatchdog {
/*< private >*/
SysBusDevice parent_obj;
/*< public >*/
MemoryRegion iomem;
qemu_irq wdogint;
uint32_t wdogclk_frq;
struct ptimer_state *timer;
uint32_t control;
uint32_t intstatus;
uint32_t lock;
uint32_t itcr;
uint32_t itop;
uint32_t resetstatus;
} CMSDKAPBWatchdog;