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 #include "qom/object.h" 17 #include "hw/ptimer.h" 18 19 #define TYPE_SYSTICK "armv7m_systick" 20 21 OBJECT_DECLARE_SIMPLE_TYPE(SysTickState, SYSTICK) 22 23 struct SysTickState { 24 /*< private >*/ 25 SysBusDevice parent_obj; 26 /*< public >*/ 27 28 uint32_t control; 29 uint32_t reload; 30 int64_t tick; 31 ptimer_state *ptimer; 32 MemoryRegion iomem; 33 qemu_irq irq; 34 }; 35 36 /* 37 * Multiplication factor to convert from system clock ticks to qemu timer 38 * ticks. This should be set (by board code, usually) to a value 39 * equal to NANOSECONDS_PER_SECOND / frq, where frq is the clock frequency 40 * in Hz of the CPU. 41 * 42 * This value is used by the systick device when it is running in 43 * its "use the CPU clock" mode (ie when SYST_CSR.CLKSOURCE == 1) to 44 * set how fast the timer should tick. 45 * 46 * TODO: we should refactor this so that rather than using a global 47 * we use a device property or something similar. This is complicated 48 * because (a) the property would need to be plumbed through from the 49 * board code down through various layers to the systick device 50 * and (b) the property needs to be modifiable after realize, because 51 * the stellaris board uses this to implement the behaviour where the 52 * guest can reprogram the PLL registers to downclock the CPU, and the 53 * systick device needs to react accordingly. Possibly this should 54 * be deferred until we have a good API for modelling clock trees. 55 */ 56 extern int system_clock_scale; 57 58 #endif 59