1 /* 2 * ARMv7M SysTick timer 3 * 4 * Copyright (c) 2006-2007 CodeSourcery. 5 * Written by Paul Brook 6 * Copyright (c) 2017 Linaro Ltd 7 * Written by Peter Maydell 8 * 9 * This code is licensed under the GPL (version 2 or later). 10 */ 11 12 #ifndef HW_TIMER_ARMV7M_SYSTICK_H 13 #define HW_TIMER_ARMV7M_SYSTICK_H 14 15 #include "hw/sysbus.h" 16 17 #define TYPE_SYSTICK "armv7m_systick" 18 19 #define SYSTICK(obj) OBJECT_CHECK(SysTickState, (obj), TYPE_SYSTICK) 20 21 typedef struct SysTickState { 22 /*< private >*/ 23 SysBusDevice parent_obj; 24 /*< public >*/ 25 26 uint32_t control; 27 uint32_t reload; 28 int64_t tick; 29 QEMUTimer *timer; 30 MemoryRegion iomem; 31 qemu_irq irq; 32 } SysTickState; 33 34 /* 35 * Multiplication factor to convert from system clock ticks to qemu timer 36 * ticks. This should be set (by board code, usually) to a value 37 * equal to NANOSECONDS_PER_SECOND / frq, where frq is the clock frequency 38 * in Hz of the CPU. 39 * 40 * This value is used by the systick device when it is running in 41 * its "use the CPU clock" mode (ie when SYST_CSR.CLKSOURCE == 1) to 42 * set how fast the timer should tick. 43 * 44 * TODO: we should refactor this so that rather than using a global 45 * we use a device property or something similar. This is complicated 46 * because (a) the property would need to be plumbed through from the 47 * board code down through various layers to the systick device 48 * and (b) the property needs to be modifiable after realize, because 49 * the stellaris board uses this to implement the behaviour where the 50 * guest can reprogram the PLL registers to downclock the CPU, and the 51 * systick device needs to react accordingly. Possibly this should 52 * be deferred until we have a good API for modelling clock trees. 53 */ 54 extern int system_clock_scale; 55 56 #endif 57