qemu/hw/pl031.c

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/*
* ARM AMBA PrimeCell PL031 RTC
*
* Copyright (c) 2007 CodeSourcery
*
* This file is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* Contributions after 2012-01-13 are licensed under the terms of the
* GNU GPL, version 2 or (at your option) any later version.
*/
#include "sysbus.h"
#include "qemu/timer.h"
#include "sysemu/sysemu.h"
//#define DEBUG_PL031
#ifdef DEBUG_PL031
#define DPRINTF(fmt, ...) \
do { printf("pl031: " fmt , ## __VA_ARGS__); } while (0)
#else
#define DPRINTF(fmt, ...) do {} while(0)
#endif
#define RTC_DR 0x00 /* Data read register */
#define RTC_MR 0x04 /* Match register */
#define RTC_LR 0x08 /* Data load register */
#define RTC_CR 0x0c /* Control register */
#define RTC_IMSC 0x10 /* Interrupt mask and set register */
#define RTC_RIS 0x14 /* Raw interrupt status register */
#define RTC_MIS 0x18 /* Masked interrupt status register */
#define RTC_ICR 0x1c /* Interrupt clear register */
typedef struct {
SysBusDevice busdev;
MemoryRegion iomem;
QEMUTimer *timer;
qemu_irq irq;
/* Needed to preserve the tick_count across migration, even if the
* absolute value of the rtc_clock is different on the source and
* destination.
*/
uint32_t tick_offset_vmstate;
uint32_t tick_offset;
uint32_t mr;
uint32_t lr;
uint32_t cr;
uint32_t im;
uint32_t is;
} pl031_state;
static const unsigned char pl031_id[] = {
0x31, 0x10, 0x14, 0x00, /* Device ID */
0x0d, 0xf0, 0x05, 0xb1 /* Cell ID */
};
static void pl031_update(pl031_state *s)
{
qemu_set_irq(s->irq, s->is & s->im);
}
static void pl031_interrupt(void * opaque)
{
pl031_state *s = (pl031_state *)opaque;
s->is = 1;
DPRINTF("Alarm raised\n");
pl031_update(s);
}
static uint32_t pl031_get_count(pl031_state *s)
{
int64_t now = qemu_get_clock_ns(rtc_clock);
return s->tick_offset + now / get_ticks_per_sec();
}
static void pl031_set_alarm(pl031_state *s)
{
uint32_t ticks;
/* The timer wraps around. This subtraction also wraps in the same way,
and gives correct results when alarm < now_ticks. */
ticks = s->mr - pl031_get_count(s);
DPRINTF("Alarm set in %ud ticks\n", ticks);
if (ticks == 0) {
qemu_del_timer(s->timer);
pl031_interrupt(s);
} else {
int64_t now = qemu_get_clock_ns(rtc_clock);
qemu_mod_timer(s->timer, now + (int64_t)ticks * get_ticks_per_sec());
}
}
static uint64_t pl031_read(void *opaque, hwaddr offset,
unsigned size)
{
pl031_state *s = (pl031_state *)opaque;
if (offset >= 0xfe0 && offset < 0x1000)
return pl031_id[(offset - 0xfe0) >> 2];
switch (offset) {
case RTC_DR:
return pl031_get_count(s);
case RTC_MR:
return s->mr;
case RTC_IMSC:
return s->im;
case RTC_RIS:
return s->is;
case RTC_LR:
return s->lr;
case RTC_CR:
/* RTC is permanently enabled. */
return 1;
case RTC_MIS:
return s->is & s->im;
case RTC_ICR:
qemu_log_mask(LOG_GUEST_ERROR,
"pl031: read of write-only register at offset 0x%x\n",
(int)offset);
break;
default:
qemu_log_mask(LOG_GUEST_ERROR,
"pl031_read: Bad offset 0x%x\n", (int)offset);
break;
}
return 0;
}
static void pl031_write(void * opaque, hwaddr offset,
uint64_t value, unsigned size)
{
pl031_state *s = (pl031_state *)opaque;
switch (offset) {
case RTC_LR:
s->tick_offset += value - pl031_get_count(s);
pl031_set_alarm(s);
break;
case RTC_MR:
s->mr = value;
pl031_set_alarm(s);
break;
case RTC_IMSC:
s->im = value & 1;
DPRINTF("Interrupt mask %d\n", s->im);
pl031_update(s);
break;
case RTC_ICR:
/* The PL031 documentation (DDI0224B) states that the interrupt is
cleared when bit 0 of the written value is set. However the
arm926e documentation (DDI0287B) states that the interrupt is
cleared when any value is written. */
DPRINTF("Interrupt cleared");
s->is = 0;
pl031_update(s);
break;
case RTC_CR:
/* Written value is ignored. */
break;
case RTC_DR:
case RTC_MIS:
case RTC_RIS:
qemu_log_mask(LOG_GUEST_ERROR,
"pl031: write to read-only register at offset 0x%x\n",
(int)offset);
break;
default:
qemu_log_mask(LOG_GUEST_ERROR,
"pl031_write: Bad offset 0x%x\n", (int)offset);
break;
}
}
static const MemoryRegionOps pl031_ops = {
.read = pl031_read,
.write = pl031_write,
.endianness = DEVICE_NATIVE_ENDIAN,
};
static int pl031_init(SysBusDevice *dev)
{
pl031_state *s = FROM_SYSBUS(pl031_state, dev);
struct tm tm;
memory_region_init_io(&s->iomem, &pl031_ops, s, "pl031", 0x1000);
sysbus_init_mmio(dev, &s->iomem);
sysbus_init_irq(dev, &s->irq);
qemu_get_timedate(&tm, 0);
s->tick_offset = mktimegm(&tm) - qemu_get_clock_ns(rtc_clock) / get_ticks_per_sec();
s->timer = qemu_new_timer_ns(rtc_clock, pl031_interrupt, s);
return 0;
}
static void pl031_pre_save(void *opaque)
{
pl031_state *s = opaque;
/* tick_offset is base_time - rtc_clock base time. Instead, we want to
* store the base time relative to the vm_clock for backwards-compatibility. */
int64_t delta = qemu_get_clock_ns(rtc_clock) - qemu_get_clock_ns(vm_clock);
s->tick_offset_vmstate = s->tick_offset + delta / get_ticks_per_sec();
}
static int pl031_post_load(void *opaque, int version_id)
{
pl031_state *s = opaque;
int64_t delta = qemu_get_clock_ns(rtc_clock) - qemu_get_clock_ns(vm_clock);
s->tick_offset = s->tick_offset_vmstate - delta / get_ticks_per_sec();
pl031_set_alarm(s);
return 0;
}
static const VMStateDescription vmstate_pl031 = {
.name = "pl031",
.version_id = 1,
.minimum_version_id = 1,
.pre_save = pl031_pre_save,
.post_load = pl031_post_load,
.fields = (VMStateField[]) {
VMSTATE_UINT32(tick_offset_vmstate, pl031_state),
VMSTATE_UINT32(mr, pl031_state),
VMSTATE_UINT32(lr, pl031_state),
VMSTATE_UINT32(cr, pl031_state),
VMSTATE_UINT32(im, pl031_state),
VMSTATE_UINT32(is, pl031_state),
VMSTATE_END_OF_LIST()
}
};
static void pl031_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
SysBusDeviceClass *k = SYS_BUS_DEVICE_CLASS(klass);
k->init = pl031_init;
dc->no_user = 1;
dc->vmsd = &vmstate_pl031;
}
static const TypeInfo pl031_info = {
.name = "pl031",
.parent = TYPE_SYS_BUS_DEVICE,
.instance_size = sizeof(pl031_state),
.class_init = pl031_class_init,
};
static void pl031_register_types(void)
{
type_register_static(&pl031_info);
}
type_init(pl031_register_types)