hw/timer/armv7m_systick.c - third_party/qemu - Git at Google

 /*
  * 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).
  */

 #include "qemu/osdep.h"
 #include "hw/timer/armv7m_systick.h"
 #include "migration/vmstate.h"
 #include "hw/irq.h"
 #include "hw/sysbus.h"
 #include "qemu/timer.h"
 #include "qemu/log.h"
 #include "qemu/module.h"
 #include "trace.h"

 /* qemu timers run at 1GHz.   We want something closer to 1MHz.  */
 #define SYSTICK_SCALE 1000ULL

 #define SYSTICK_ENABLE    (1 << 0)
 #define SYSTICK_TICKINT   (1 << 1)
 #define SYSTICK_CLKSOURCE (1 << 2)
 #define SYSTICK_COUNTFLAG (1 << 16)

 int system_clock_scale;

 /* Conversion factor from qemu timer to SysTick frequencies.  */
 static inline int64_t systick_scale(SysTickState *s)
 {
     if (s->control & SYSTICK_CLKSOURCE) {
         return system_clock_scale;
     } else {
         return 1000;
     }
 }

 static void systick_reload(SysTickState *s, int reset)
 {
     /* The Cortex-M3 Devices Generic User Guide says that "When the
      * ENABLE bit is set to 1, the counter loads the RELOAD value from the
      * SYST RVR register and then counts down". So, we need to check the
      * ENABLE bit before reloading the value.
      */
     trace_systick_reload();

     if ((s->control & SYSTICK_ENABLE) == 0) {
         return;
     }

     if (reset) {
         s->tick = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
     }
     s->tick += (s->reload + 1) * systick_scale(s);
     timer_mod(s->timer, s->tick);
 }

 static void systick_timer_tick(void *opaque)
 {
     SysTickState *s = (SysTickState *)opaque;

     trace_systick_timer_tick();

     s->control |= SYSTICK_COUNTFLAG;
     if (s->control & SYSTICK_TICKINT) {
         /* Tell the NVIC to pend the SysTick exception */
         qemu_irq_pulse(s->irq);
     }
     if (s->reload == 0) {
         s->control &= ~SYSTICK_ENABLE;
     } else {
         systick_reload(s, 0);
     }
 }

 static MemTxResult systick_read(void *opaque, hwaddr addr, uint64_t *data,
                                 unsigned size, MemTxAttrs attrs)
 {
     SysTickState *s = opaque;
     uint32_t val;

     if (attrs.user) {
         /* Generate BusFault for unprivileged accesses */
         return MEMTX_ERROR;
     }

     switch (addr) {
     case 0x0: /* SysTick Control and Status.  */
         val = s->control;
         s->control &= ~SYSTICK_COUNTFLAG;
         break;
     case 0x4: /* SysTick Reload Value.  */
         val = s->reload;
         break;
     case 0x8: /* SysTick Current Value.  */
     {
         int64_t t;

         if ((s->control & SYSTICK_ENABLE) == 0) {
             val = 0;
             break;
         }
         t = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
         if (t >= s->tick) {
             val = 0;
             break;
         }
         val = ((s->tick - (t + 1)) / systick_scale(s)) + 1;
         /* The interrupt in triggered when the timer reaches zero.
            However the counter is not reloaded until the next clock
            tick.  This is a hack to return zero during the first tick.  */
         if (val > s->reload) {
             val = 0;
         }
         break;
     }
     case 0xc: /* SysTick Calibration Value.  */
         val = 10000;
         break;
     default:
         val = 0;
         qemu_log_mask(LOG_GUEST_ERROR,
                       "SysTick: Bad read offset 0x%" HWADDR_PRIx "\n", addr);
         break;
     }

     trace_systick_read(addr, val, size);
     *data = val;
     return MEMTX_OK;
 }

 static MemTxResult systick_write(void *opaque, hwaddr addr,
                                  uint64_t value, unsigned size,
                                  MemTxAttrs attrs)
 {
     SysTickState *s = opaque;

     if (attrs.user) {
         /* Generate BusFault for unprivileged accesses */
         return MEMTX_ERROR;
     }

     trace_systick_write(addr, value, size);

     switch (addr) {
     case 0x0: /* SysTick Control and Status.  */
     {
         uint32_t oldval = s->control;

         s->control &= 0xfffffff8;
         s->control |= value & 7;
         if ((oldval ^ value) & SYSTICK_ENABLE) {
             int64_t now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
             if (value & SYSTICK_ENABLE) {
                 if (s->tick) {
                     s->tick += now;
                     timer_mod(s->timer, s->tick);
                 } else {
                     systick_reload(s, 1);
                 }
             } else {
                 timer_del(s->timer);
                 s->tick -= now;
                 if (s->tick < 0) {
                     s->tick = 0;
                 }
             }
         } else if ((oldval ^ value) & SYSTICK_CLKSOURCE) {
             /* This is a hack. Force the timer to be reloaded
                when the reference clock is changed.  */
             systick_reload(s, 1);
         }
         break;
     }
     case 0x4: /* SysTick Reload Value.  */
         s->reload = value;
         break;
     case 0x8: /* SysTick Current Value.  Writes reload the timer.  */
         systick_reload(s, 1);
         s->control &= ~SYSTICK_COUNTFLAG;
         break;
     default:
         qemu_log_mask(LOG_GUEST_ERROR,
                       "SysTick: Bad write offset 0x%" HWADDR_PRIx "\n", addr);
     }
     return MEMTX_OK;
 }

 static const MemoryRegionOps systick_ops = {
     .read_with_attrs = systick_read,
     .write_with_attrs = systick_write,
     .endianness = DEVICE_NATIVE_ENDIAN,
     .valid.min_access_size = 4,
     .valid.max_access_size = 4,
 };

 static void systick_reset(DeviceState *dev)
 {
     SysTickState *s = SYSTICK(dev);

     s->control = 0;
     s->reload = 0;
     s->tick = 0;
     timer_del(s->timer);
 }

 static void systick_instance_init(Object *obj)
 {
     SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
     SysTickState *s = SYSTICK(obj);

     memory_region_init_io(&s->iomem, obj, &systick_ops, s, "systick", 0xe0);
     sysbus_init_mmio(sbd, &s->iomem);
     sysbus_init_irq(sbd, &s->irq);
 }

 static void systick_realize(DeviceState *dev, Error **errp)
 {
     SysTickState *s = SYSTICK(dev);
     s->timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, systick_timer_tick, s);
 }

 static const VMStateDescription vmstate_systick = {
     .name = "armv7m_systick",
     .version_id = 1,
     .minimum_version_id = 1,
     .fields = (VMStateField[]) {
         VMSTATE_UINT32(control, SysTickState),
         VMSTATE_UINT32(reload, SysTickState),
         VMSTATE_INT64(tick, SysTickState),
         VMSTATE_TIMER_PTR(timer, SysTickState),
         VMSTATE_END_OF_LIST()
     }
 };

 static void systick_class_init(ObjectClass *klass, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(klass);

     dc->vmsd = &vmstate_systick;
     dc->reset = systick_reset;
     dc->realize = systick_realize;
 }

 static const TypeInfo armv7m_systick_info = {
     .name = TYPE_SYSTICK,
     .parent = TYPE_SYS_BUS_DEVICE,
     .instance_init = systick_instance_init,
     .instance_size = sizeof(SysTickState),
     .class_init = systick_class_init,
 };

 static void armv7m_systick_register_types(void)
 {
     type_register_static(&armv7m_systick_info);
 }

 type_init(armv7m_systick_register_types)
	/*
	* 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).
	*/

	#include "qemu/osdep.h"
	#include "hw/timer/armv7m_systick.h"
	#include "migration/vmstate.h"
	#include "hw/irq.h"
	#include "hw/sysbus.h"
	#include "qemu/timer.h"
	#include "qemu/log.h"
	#include "qemu/module.h"
	#include "trace.h"

	/* qemu timers run at 1GHz. We want something closer to 1MHz. */
	#define SYSTICK_SCALE 1000ULL

	#define SYSTICK_ENABLE (1 << 0)
	#define SYSTICK_TICKINT (1 << 1)
	#define SYSTICK_CLKSOURCE (1 << 2)
	#define SYSTICK_COUNTFLAG (1 << 16)

	int system_clock_scale;

	/* Conversion factor from qemu timer to SysTick frequencies. */
	static inline int64_t systick_scale(SysTickState *s)
	{
	if (s->control & SYSTICK_CLKSOURCE) {
	return system_clock_scale;
	} else {
	return 1000;
	}
	}

	static void systick_reload(SysTickState *s, int reset)
	{
	/* The Cortex-M3 Devices Generic User Guide says that "When the
	* ENABLE bit is set to 1, the counter loads the RELOAD value from the
	* SYST RVR register and then counts down". So, we need to check the
	* ENABLE bit before reloading the value.
	*/
	trace_systick_reload();

	if ((s->control & SYSTICK_ENABLE) == 0) {
	return;
	}

	if (reset) {
	s->tick = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
	}
	s->tick += (s->reload + 1) * systick_scale(s);
	timer_mod(s->timer, s->tick);
	}

	static void systick_timer_tick(void *opaque)
	{
	SysTickState s = (SysTickState )opaque;

	trace_systick_timer_tick();

	s->control \|= SYSTICK_COUNTFLAG;
	if (s->control & SYSTICK_TICKINT) {
	/* Tell the NVIC to pend the SysTick exception */
	qemu_irq_pulse(s->irq);
	}
	if (s->reload == 0) {
	s->control &= ~SYSTICK_ENABLE;
	} else {
	systick_reload(s, 0);
	}
	}

	static MemTxResult systick_read(void opaque, hwaddr addr, uint64_t data,
	unsigned size, MemTxAttrs attrs)
	{
	SysTickState *s = opaque;
	uint32_t val;

	if (attrs.user) {
	/* Generate BusFault for unprivileged accesses */
	return MEMTX_ERROR;
	}

	switch (addr) {
	case 0x0: /* SysTick Control and Status. */
	val = s->control;
	s->control &= ~SYSTICK_COUNTFLAG;
	break;
	case 0x4: /* SysTick Reload Value. */
	val = s->reload;
	break;
	case 0x8: /* SysTick Current Value. */
	{
	int64_t t;

	if ((s->control & SYSTICK_ENABLE) == 0) {
	val = 0;
	break;
	}
	t = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
	if (t >= s->tick) {
	val = 0;
	break;
	}
	val = ((s->tick - (t + 1)) / systick_scale(s)) + 1;
	/* The interrupt in triggered when the timer reaches zero.
	However the counter is not reloaded until the next clock
	tick. This is a hack to return zero during the first tick. */
	if (val > s->reload) {
	val = 0;
	}
	break;
	}
	case 0xc: /* SysTick Calibration Value. */
	val = 10000;
	break;
	default:
	val = 0;
	qemu_log_mask(LOG_GUEST_ERROR,
	"SysTick: Bad read offset 0x%" HWADDR_PRIx "\n", addr);
	break;
	}

	trace_systick_read(addr, val, size);
	*data = val;
	return MEMTX_OK;
	}

	static MemTxResult systick_write(void *opaque, hwaddr addr,
	uint64_t value, unsigned size,
	MemTxAttrs attrs)
	{
	SysTickState *s = opaque;

	if (attrs.user) {
	/* Generate BusFault for unprivileged accesses */
	return MEMTX_ERROR;
	}

	trace_systick_write(addr, value, size);

	switch (addr) {
	case 0x0: /* SysTick Control and Status. */
	{
	uint32_t oldval = s->control;

	s->control &= 0xfffffff8;
	s->control \|= value & 7;
	if ((oldval ^ value) & SYSTICK_ENABLE) {
	int64_t now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
	if (value & SYSTICK_ENABLE) {
	if (s->tick) {
	s->tick += now;
	timer_mod(s->timer, s->tick);
	} else {
	systick_reload(s, 1);
	}
	} else {
	timer_del(s->timer);
	s->tick -= now;
	if (s->tick < 0) {
	s->tick = 0;
	}
	}
	} else if ((oldval ^ value) & SYSTICK_CLKSOURCE) {
	/* This is a hack. Force the timer to be reloaded
	when the reference clock is changed. */
	systick_reload(s, 1);
	}
	break;
	}
	case 0x4: /* SysTick Reload Value. */
	s->reload = value;
	break;
	case 0x8: /* SysTick Current Value. Writes reload the timer. */
	systick_reload(s, 1);
	s->control &= ~SYSTICK_COUNTFLAG;
	break;
	default:
	qemu_log_mask(LOG_GUEST_ERROR,
	"SysTick: Bad write offset 0x%" HWADDR_PRIx "\n", addr);
	}
	return MEMTX_OK;
	}

	static const MemoryRegionOps systick_ops = {
	.read_with_attrs = systick_read,
	.write_with_attrs = systick_write,
	.endianness = DEVICE_NATIVE_ENDIAN,
	.valid.min_access_size = 4,
	.valid.max_access_size = 4,
	};

	static void systick_reset(DeviceState *dev)
	{
	SysTickState *s = SYSTICK(dev);

	s->control = 0;
	s->reload = 0;
	s->tick = 0;
	timer_del(s->timer);
	}

	static void systick_instance_init(Object *obj)
	{
	SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
	SysTickState *s = SYSTICK(obj);

	memory_region_init_io(&s->iomem, obj, &systick_ops, s, "systick", 0xe0);
	sysbus_init_mmio(sbd, &s->iomem);
	sysbus_init_irq(sbd, &s->irq);
	}

	static void systick_realize(DeviceState dev, Error *errp)
	{
	SysTickState *s = SYSTICK(dev);
	s->timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, systick_timer_tick, s);
	}

	static const VMStateDescription vmstate_systick = {
	.name = "armv7m_systick",
	.version_id = 1,
	.minimum_version_id = 1,
	.fields = (VMStateField[]) {
	VMSTATE_UINT32(control, SysTickState),
	VMSTATE_UINT32(reload, SysTickState),
	VMSTATE_INT64(tick, SysTickState),
	VMSTATE_TIMER_PTR(timer, SysTickState),
	VMSTATE_END_OF_LIST()
	}
	};

	static void systick_class_init(ObjectClass klass, void data)
	{
	DeviceClass *dc = DEVICE_CLASS(klass);

	dc->vmsd = &vmstate_systick;
	dc->reset = systick_reset;
	dc->realize = systick_realize;
	}

	static const TypeInfo armv7m_systick_info = {
	.name = TYPE_SYSTICK,
	.parent = TYPE_SYS_BUS_DEVICE,
	.instance_init = systick_instance_init,
	.instance_size = sizeof(SysTickState),
	.class_init = systick_class_init,
	};

	static void armv7m_systick_register_types(void)
	{
	type_register_static(&armv7m_systick_info);
	}

	type_init(armv7m_systick_register_types)