blob: 801d1dba7410849dd675b4eaa52664d295c6f84d [file] [log] [blame]
/*
* ARM CMSDK APB timer emulation
*
* Copyright (c) 2017 Linaro Limited
* Written by Peter Maydell
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 or
* (at your option) any later version.
*/
/* This is a model of the "APB timer" which is part of the Cortex-M
* System Design Kit (CMSDK) and documented in the Cortex-M System
* Design Kit Technical Reference Manual (ARM DDI0479C):
* https://developer.arm.com/products/system-design/system-design-kits/cortex-m-system-design-kit
*
* The hardware has an EXTIN input wire, which can be configured
* by the guest to act either as a 'timer enable' (timer does not run
* when EXTIN is low), or as a 'timer clock' (timer runs at frequency
* of EXTIN clock, not PCLK frequency). We don't model this.
*
* The documentation is not very clear about the exact behaviour;
* we choose to implement that the interrupt is triggered when
* the counter goes from 1 to 0, that the counter then holds at 0
* for one clock cycle before reloading from the RELOAD register,
* and that if the RELOAD register is 0 this does not cause an
* interrupt (as there is no further 1->0 transition).
*/
#include "qemu/osdep.h"
#include "qemu/log.h"
#include "qemu/main-loop.h"
#include "qapi/error.h"
#include "trace.h"
#include "hw/sysbus.h"
#include "hw/registerfields.h"
#include "hw/timer/cmsdk-apb-timer.h"
REG32(CTRL, 0)
FIELD(CTRL, EN, 0, 1)
FIELD(CTRL, SELEXTEN, 1, 1)
FIELD(CTRL, SELEXTCLK, 2, 1)
FIELD(CTRL, IRQEN, 3, 1)
REG32(VALUE, 4)
REG32(RELOAD, 8)
REG32(INTSTATUS, 0xc)
FIELD(INTSTATUS, IRQ, 0, 1)
REG32(PID4, 0xFD0)
REG32(PID5, 0xFD4)
REG32(PID6, 0xFD8)
REG32(PID7, 0xFDC)
REG32(PID0, 0xFE0)
REG32(PID1, 0xFE4)
REG32(PID2, 0xFE8)
REG32(PID3, 0xFEC)
REG32(CID0, 0xFF0)
REG32(CID1, 0xFF4)
REG32(CID2, 0xFF8)
REG32(CID3, 0xFFC)
/* PID/CID values */
static const int timer_id[] = {
0x04, 0x00, 0x00, 0x00, /* PID4..PID7 */
0x22, 0xb8, 0x1b, 0x00, /* PID0..PID3 */
0x0d, 0xf0, 0x05, 0xb1, /* CID0..CID3 */
};
static void cmsdk_apb_timer_update(CMSDKAPBTIMER *s)
{
qemu_set_irq(s->timerint, !!(s->intstatus & R_INTSTATUS_IRQ_MASK));
}
static uint64_t cmsdk_apb_timer_read(void *opaque, hwaddr offset, unsigned size)
{
CMSDKAPBTIMER *s = CMSDK_APB_TIMER(opaque);
uint64_t r;
switch (offset) {
case A_CTRL:
r = s->ctrl;
break;
case A_VALUE:
r = ptimer_get_count(s->timer);
break;
case A_RELOAD:
r = ptimer_get_limit(s->timer);
break;
case A_INTSTATUS:
r = s->intstatus;
break;
case A_PID4 ... A_CID3:
r = timer_id[(offset - A_PID4) / 4];
break;
default:
qemu_log_mask(LOG_GUEST_ERROR,
"CMSDK APB timer read: bad offset %x\n", (int) offset);
r = 0;
break;
}
trace_cmsdk_apb_timer_read(offset, r, size);
return r;
}
static void cmsdk_apb_timer_write(void *opaque, hwaddr offset, uint64_t value,
unsigned size)
{
CMSDKAPBTIMER *s = CMSDK_APB_TIMER(opaque);
trace_cmsdk_apb_timer_write(offset, value, size);
switch (offset) {
case A_CTRL:
if (value & 6) {
/* Bits [1] and [2] enable using EXTIN as either clock or
* an enable line. We don't model this.
*/
qemu_log_mask(LOG_UNIMP,
"CMSDK APB timer: EXTIN input not supported\n");
}
s->ctrl = value & 0xf;
if (s->ctrl & R_CTRL_EN_MASK) {
ptimer_run(s->timer, ptimer_get_limit(s->timer) == 0);
} else {
ptimer_stop(s->timer);
}
break;
case A_RELOAD:
/* Writing to reload also sets the current timer value */
if (!value) {
ptimer_stop(s->timer);
}
ptimer_set_limit(s->timer, value, 1);
if (value && (s->ctrl & R_CTRL_EN_MASK)) {
/*
* Make sure timer is running (it might have stopped if this
* was an expired one-shot timer)
*/
ptimer_run(s->timer, 0);
}
break;
case A_VALUE:
if (!value && !ptimer_get_limit(s->timer)) {
ptimer_stop(s->timer);
}
ptimer_set_count(s->timer, value);
if (value && (s->ctrl & R_CTRL_EN_MASK)) {
ptimer_run(s->timer, ptimer_get_limit(s->timer) == 0);
}
break;
case A_INTSTATUS:
/* Just one bit, which is W1C. */
value &= 1;
s->intstatus &= ~value;
cmsdk_apb_timer_update(s);
break;
case A_PID4 ... A_CID3:
qemu_log_mask(LOG_GUEST_ERROR,
"CMSDK APB timer write: write to RO offset 0x%x\n",
(int)offset);
break;
default:
qemu_log_mask(LOG_GUEST_ERROR,
"CMSDK APB timer write: bad offset 0x%x\n", (int) offset);
break;
}
}
static const MemoryRegionOps cmsdk_apb_timer_ops = {
.read = cmsdk_apb_timer_read,
.write = cmsdk_apb_timer_write,
.endianness = DEVICE_LITTLE_ENDIAN,
};
static void cmsdk_apb_timer_tick(void *opaque)
{
CMSDKAPBTIMER *s = CMSDK_APB_TIMER(opaque);
if (s->ctrl & R_CTRL_IRQEN_MASK) {
s->intstatus |= R_INTSTATUS_IRQ_MASK;
cmsdk_apb_timer_update(s);
}
}
static void cmsdk_apb_timer_reset(DeviceState *dev)
{
CMSDKAPBTIMER *s = CMSDK_APB_TIMER(dev);
trace_cmsdk_apb_timer_reset();
s->ctrl = 0;
s->intstatus = 0;
ptimer_stop(s->timer);
/* Set the limit and the count */
ptimer_set_limit(s->timer, 0, 1);
}
static void cmsdk_apb_timer_init(Object *obj)
{
SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
CMSDKAPBTIMER *s = CMSDK_APB_TIMER(obj);
memory_region_init_io(&s->iomem, obj, &cmsdk_apb_timer_ops,
s, "cmsdk-apb-timer", 0x1000);
sysbus_init_mmio(sbd, &s->iomem);
sysbus_init_irq(sbd, &s->timerint);
}
static void cmsdk_apb_timer_realize(DeviceState *dev, Error **errp)
{
CMSDKAPBTIMER *s = CMSDK_APB_TIMER(dev);
QEMUBH *bh;
if (s->pclk_frq == 0) {
error_setg(errp, "CMSDK APB timer: pclk-frq property must be set");
return;
}
bh = qemu_bh_new(cmsdk_apb_timer_tick, s);
s->timer = ptimer_init(bh,
PTIMER_POLICY_WRAP_AFTER_ONE_PERIOD |
PTIMER_POLICY_TRIGGER_ONLY_ON_DECREMENT |
PTIMER_POLICY_NO_IMMEDIATE_RELOAD |
PTIMER_POLICY_NO_COUNTER_ROUND_DOWN);
ptimer_set_freq(s->timer, s->pclk_frq);
}
static const VMStateDescription cmsdk_apb_timer_vmstate = {
.name = "cmsdk-apb-timer",
.version_id = 1,
.minimum_version_id = 1,
.fields = (VMStateField[]) {
VMSTATE_PTIMER(timer, CMSDKAPBTIMER),
VMSTATE_UINT32(ctrl, CMSDKAPBTIMER),
VMSTATE_UINT32(value, CMSDKAPBTIMER),
VMSTATE_UINT32(reload, CMSDKAPBTIMER),
VMSTATE_UINT32(intstatus, CMSDKAPBTIMER),
VMSTATE_END_OF_LIST()
}
};
static Property cmsdk_apb_timer_properties[] = {
DEFINE_PROP_UINT32("pclk-frq", CMSDKAPBTIMER, pclk_frq, 0),
DEFINE_PROP_END_OF_LIST(),
};
static void cmsdk_apb_timer_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
dc->realize = cmsdk_apb_timer_realize;
dc->vmsd = &cmsdk_apb_timer_vmstate;
dc->reset = cmsdk_apb_timer_reset;
dc->props = cmsdk_apb_timer_properties;
}
static const TypeInfo cmsdk_apb_timer_info = {
.name = TYPE_CMSDK_APB_TIMER,
.parent = TYPE_SYS_BUS_DEVICE,
.instance_size = sizeof(CMSDKAPBTIMER),
.instance_init = cmsdk_apb_timer_init,
.class_init = cmsdk_apb_timer_class_init,
};
static void cmsdk_apb_timer_register_types(void)
{
type_register_static(&cmsdk_apb_timer_info);
}
type_init(cmsdk_apb_timer_register_types);