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/*
* ARMv7M SysTick timer
*
* Copyright (c) 2006-2007 CodeSourcery.
* Written by Paul Brook
* Copyright (c) 2017 Linaro Ltd
* Written by Peter Maydell
*
* This code is licensed under the GPL (version 2 or later).
*/
#ifndef HW_TIMER_ARMV7M_SYSTICK_H
#define HW_TIMER_ARMV7M_SYSTICK_H
#include "hw/sysbus.h"
#include "qom/object.h"
#include "hw/ptimer.h"
#include "hw/clock.h"
#define TYPE_SYSTICK "armv7m_systick"
OBJECT_DECLARE_SIMPLE_TYPE(SysTickState, SYSTICK)
/*
* QEMU interface:
* + sysbus MMIO region 0 is the register interface (covering
* the registers which are mapped at address 0xE000E010)
* + sysbus IRQ 0 is the interrupt line to the NVIC
* + Clock input "refclk" is the external reference clock
* (used when SYST_CSR.CLKSOURCE == 0)
* + Clock input "cpuclk" is the main CPU clock
* (used when SYST_CSR.CLKSOURCE == 1)
*/
struct SysTickState {
/*< private >*/
SysBusDevice parent_obj;
/*< public >*/
uint32_t control;
uint32_t reload;
int64_t tick;
ptimer_state *ptimer;
MemoryRegion iomem;
qemu_irq irq;
Clock *refclk;
Clock *cpuclk;
};
/*
* Multiplication factor to convert from system clock ticks to qemu timer
* ticks. This should be set (by board code, usually) to a value
* equal to NANOSECONDS_PER_SECOND / frq, where frq is the clock frequency
* in Hz of the CPU.
*
* This value is used by the systick device when it is running in
* its "use the CPU clock" mode (ie when SYST_CSR.CLKSOURCE == 1) to
* set how fast the timer should tick.
*
* TODO: we should refactor this so that rather than using a global
* we use a device property or something similar. This is complicated
* because (a) the property would need to be plumbed through from the
* board code down through various layers to the systick device
* and (b) the property needs to be modifiable after realize, because
* the stellaris board uses this to implement the behaviour where the
* guest can reprogram the PLL registers to downclock the CPU, and the
* systick device needs to react accordingly. Possibly this should
* be deferred until we have a good API for modelling clock trees.
*/
extern int system_clock_scale;
#endif
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