/*
* Arm SSE Subsystem System Timer
*
* Copyright (c) 2020 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 "System timer" which is documented in
* the Arm SSE-123 Example Subsystem Technical Reference Manual:
* https://developer.arm.com/documentation/101370/latest/
*
* The timer is based around a simple 64-bit incrementing counter
* (readable from CNTPCT_HI/LO). The timer fires when
* Counter - CompareValue >= 0.
* The CompareValue is guest-writable, via CNTP_CVAL_HI/LO.
* CNTP_TVAL is an alternative view of the CompareValue defined by
* TimerValue = CompareValue[31:0] - Counter[31:0]
* which can be both read and written.
* This part is similar to the generic timer in an Arm A-class CPU.
*
* The timer also has a separate auto-increment timer. When this
* timer is enabled, then the AutoIncrValue is set to:
* AutoIncrValue = Reload + Counter
* and this timer fires when
* Counter - AutoIncrValue >= 0
* at which point, an interrupt is generated and the new AutoIncrValue
* is calculated.
* When the auto-increment timer is enabled, interrupt generation
* via the compare/timervalue registers is disabled.
*/
#include "qemu/osdep.h"
#include "qemu/log.h"
#include "qemu/timer.h"
#include "qapi/error.h"
#include "trace.h"
#include "hw/timer/sse-timer.h"
#include "hw/timer/sse-counter.h"
#include "hw/sysbus.h"
#include "hw/irq.h"
#include "hw/registerfields.h"
#include "hw/clock.h"
#include "hw/qdev-clock.h"
#include "hw/qdev-properties.h"
#include "migration/vmstate.h"
REG32(CNTPCT_LO, 0x0)
REG32(CNTPCT_HI, 0x4)
REG32(CNTFRQ, 0x10)
REG32(CNTP_CVAL_LO, 0x20)
REG32(CNTP_CVAL_HI, 0x24)
REG32(CNTP_TVAL, 0x28)
REG32(CNTP_CTL, 0x2c)
FIELD(CNTP_CTL, ENABLE, 0, 1)
FIELD(CNTP_CTL, IMASK, 1, 1)
FIELD(CNTP_CTL, ISTATUS, 2, 1)
REG32(CNTP_AIVAL_LO, 0x40)
REG32(CNTP_AIVAL_HI, 0x44)
REG32(CNTP_AIVAL_RELOAD, 0x48)
REG32(CNTP_AIVAL_CTL, 0x4c)
FIELD(CNTP_AIVAL_CTL, EN, 0, 1)
FIELD(CNTP_AIVAL_CTL, CLR, 1, 1)
REG32(CNTP_CFG, 0x50)
FIELD(CNTP_CFG, AIVAL, 0, 4)
#define R_CNTP_CFG_AIVAL_IMPLEMENTED 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 */
0xb7, 0xb0, 0x0b, 0x00, /* PID0..PID3 */
0x0d, 0xf0, 0x05, 0xb1, /* CID0..CID3 */
};
static bool sse_is_autoinc(SSETimer *s)
{
return (s->cntp_aival_ctl & R_CNTP_AIVAL_CTL_EN_MASK) != 0;
}
static bool sse_enabled(SSETimer *s)
{
return (s->cntp_ctl & R_CNTP_CTL_ENABLE_MASK) != 0;
}
static uint64_t sse_cntpct(SSETimer *s)
{
/* Return the CNTPCT value for the current time */
return sse_counter_for_timestamp(s->counter,
qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL));
}
static bool sse_timer_status(SSETimer *s)
{
/*
* Return true if timer condition is met. This is used for both
* the CNTP_CTL.ISTATUS bit and for whether (unless masked) we
* assert our IRQ.
* The documentation is unclear about the behaviour of ISTATUS when
* in autoincrement mode; we assume that it follows CNTP_AIVAL_CTL.CLR
* (ie whether the autoincrement timer is asserting the interrupt).
*/
if (!sse_enabled(s)) {
return false;
}
if (sse_is_autoinc(s)) {
return s->cntp_aival_ctl & R_CNTP_AIVAL_CTL_CLR_MASK;
} else {
return sse_cntpct(s) >= s->cntp_cval;
}
}
static void sse_update_irq(SSETimer *s)
{
bool irqstate = (!(s->cntp_ctl & R_CNTP_CTL_IMASK_MASK) &&
sse_timer_status(s));
qemu_set_irq(s->irq, irqstate);
}
static void sse_set_timer(SSETimer *s, uint64_t nexttick)
{
/* Set the timer to expire at nexttick */
uint64_t expiry = sse_counter_tick_to_time(s->counter, nexttick);
if (expiry <= INT64_MAX) {
timer_mod_ns(&s->timer, expiry);
} else {
/*
* nexttick is so far in the future that it would overflow the
* signed 64-bit range of a QEMUTimer. Since timer_mod_ns()
* expiry times are absolute, not relative, we are never going
* to be able to set the timer to this value, so we must just
* assume that guest execution can never run so long that it
* reaches the theoretical point when the timer fires.
* This is also the code path for "counter is not running",
* which is signalled by expiry == UINT64_MAX.
*/
timer_del(&s->timer);
}
}
static void sse_recalc_timer(SSETimer *s)
{
/* Recalculate the normal timer */
uint64_t count, nexttick;
if (sse_is_autoinc(s)) {
return;
}
if (!sse_enabled(s)) {
timer_del(&s->timer);
return;
}
count = sse_cntpct(s);
if (count >= s->cntp_cval) {
/*
* Timer condition already met. In theory we have a transition when
* the count rolls back over to 0, but that is so far in the future
* that it is not representable as a timer_mod() expiry, so in
* fact sse_set_timer() will always just delete the timer.
*/
nexttick = UINT64_MAX;
} else {
/* Next transition is when count hits cval */
nexttick = s->cntp_cval;
}
sse_set_timer(s, nexttick);
sse_update_irq(s);
}
static void sse_autoinc(SSETimer *s)
{
/* Auto-increment the AIVAL, and set the timer accordingly */
s->cntp_aival = sse_cntpct(s) + s->cntp_aival_reload;
sse_set_timer(s, s->cntp_aival);
}
static void sse_timer_cb(void *opaque)
{
SSETimer *s = SSE_TIMER(opaque);
if (sse_is_autoinc(s)) {
uint64_t count = sse_cntpct(s);
if (count >= s->cntp_aival) {
/* Timer condition met, set CLR and do another autoinc */
s->cntp_aival_ctl |= R_CNTP_AIVAL_CTL_CLR_MASK;
s->cntp_aival = count + s->cntp_aival_reload;
}
sse_set_timer(s, s->cntp_aival);
sse_update_irq(s);
} else {
sse_recalc_timer(s);
}
}
static uint64_t sse_timer_read(void *opaque, hwaddr offset, unsigned size)
{
SSETimer *s = SSE_TIMER(opaque);
uint64_t r;
switch (offset) {
case A_CNTPCT_LO:
r = extract64(sse_cntpct(s), 0, 32);
break;
case A_CNTPCT_HI:
r = extract64(sse_cntpct(s), 32, 32);
break;
case A_CNTFRQ:
r = s->cntfrq;
break;
case A_CNTP_CVAL_LO:
r = extract64(s->cntp_cval, 0, 32);
break;
case A_CNTP_CVAL_HI:
r = extract64(s->cntp_cval, 32, 32);
break;
case A_CNTP_TVAL:
r = extract64(s->cntp_cval - sse_cntpct(s), 0, 32);
break;
case A_CNTP_CTL:
r = s->cntp_ctl;
if (sse_timer_status(s)) {
r |= R_CNTP_CTL_ISTATUS_MASK;
}
break;
case A_CNTP_AIVAL_LO:
r = extract64(s->cntp_aival, 0, 32);
break;
case A_CNTP_AIVAL_HI:
r = extract64(s->cntp_aival, 32, 32);
break;
case A_CNTP_AIVAL_RELOAD:
r = s->cntp_aival_reload;
break;
case A_CNTP_AIVAL_CTL:
/*
* All the bits of AIVAL_CTL are documented as WO, but this is probably
* a documentation error. We implement them as readable.
*/
r = s->cntp_aival_ctl;
break;
case A_CNTP_CFG:
r = R_CNTP_CFG_AIVAL_IMPLEMENTED << R_CNTP_CFG_AIVAL_SHIFT;
break;
case A_PID4 ... A_CID3:
r = timer_id[(offset - A_PID4) / 4];
break;
default:
qemu_log_mask(LOG_GUEST_ERROR,
"SSE System Timer read: bad offset 0x%x",
(unsigned) offset);
r = 0;
break;
}
trace_sse_timer_read(offset, r, size);
return r;
}
static void sse_timer_write(void *opaque, hwaddr offset, uint64_t value,
unsigned size)
{
SSETimer *s = SSE_TIMER(opaque);
trace_sse_timer_write(offset, value, size);
switch (offset) {
case A_CNTFRQ:
s->cntfrq = value;
break;
case A_CNTP_CVAL_LO:
s->cntp_cval = deposit64(s->cntp_cval, 0, 32, value);
sse_recalc_timer(s);
break;
case A_CNTP_CVAL_HI:
s->cntp_cval = deposit64(s->cntp_cval, 32, 32, value);
sse_recalc_timer(s);
break;
case A_CNTP_TVAL:
s->cntp_cval = sse_cntpct(s) + sextract64(value, 0, 32);
sse_recalc_timer(s);
break;
case A_CNTP_CTL:
{
uint32_t old_ctl = s->cntp_ctl;
value &= R_CNTP_CTL_ENABLE_MASK | R_CNTP_CTL_IMASK_MASK;
s->cntp_ctl = value;
if ((old_ctl ^ s->cntp_ctl) & R_CNTP_CTL_ENABLE_MASK) {
if (sse_enabled(s)) {
if (sse_is_autoinc(s)) {
sse_autoinc(s);
} else {
sse_recalc_timer(s);
}
}
}
sse_update_irq(s);
break;
}
case A_CNTP_AIVAL_RELOAD:
s->cntp_aival_reload = value;
break;
case A_CNTP_AIVAL_CTL:
{
uint32_t old_ctl = s->cntp_aival_ctl;
/* EN bit is writable; CLR bit is write-0-to-clear, write-1-ignored */
s->cntp_aival_ctl &= ~R_CNTP_AIVAL_CTL_EN_MASK;
s->cntp_aival_ctl |= value & R_CNTP_AIVAL_CTL_EN_MASK;
if (!(value & R_CNTP_AIVAL_CTL_CLR_MASK)) {
s->cntp_aival_ctl &= ~R_CNTP_AIVAL_CTL_CLR_MASK;
}
if ((old_ctl ^ s->cntp_aival_ctl) & R_CNTP_AIVAL_CTL_EN_MASK) {
/* Auto-increment toggled on/off */
if (sse_enabled(s)) {
if (sse_is_autoinc(s)) {
sse_autoinc(s);
} else {
sse_recalc_timer(s);
}
}
}
sse_update_irq(s);
break;
}
case A_CNTPCT_LO:
case A_CNTPCT_HI:
case A_CNTP_CFG:
case A_CNTP_AIVAL_LO:
case A_CNTP_AIVAL_HI:
case A_PID4 ... A_CID3:
qemu_log_mask(LOG_GUEST_ERROR,
"SSE System Timer write: write to RO offset 0x%x\n",
(unsigned)offset);
break;
default:
qemu_log_mask(LOG_GUEST_ERROR,
"SSE System Timer write: bad offset 0x%x\n",
(unsigned)offset);
break;
}
}
static const MemoryRegionOps sse_timer_ops = {
.read = sse_timer_read,
.write = sse_timer_write,
.endianness = DEVICE_LITTLE_ENDIAN,
.valid.min_access_size = 4,
.valid.max_access_size = 4,
};
static void sse_timer_reset(DeviceState *dev)
{
SSETimer *s = SSE_TIMER(dev);
trace_sse_timer_reset();
timer_del(&s->timer);
s->cntfrq = 0;
s->cntp_ctl = 0;
s->cntp_cval = 0;
s->cntp_aival = 0;
s->cntp_aival_ctl = 0;
s->cntp_aival_reload = 0;
}
static void sse_timer_counter_callback(Notifier *notifier, void *data)
{
SSETimer *s = container_of(notifier, SSETimer, counter_notifier);
/* System counter told us we need to recalculate */
if (sse_enabled(s)) {
if (sse_is_autoinc(s)) {
sse_set_timer(s, s->cntp_aival);
} else {
sse_recalc_timer(s);
}
}
}
static void sse_timer_init(Object *obj)
{
SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
SSETimer *s = SSE_TIMER(obj);
memory_region_init_io(&s->iomem, obj, &sse_timer_ops,
s, "sse-timer", 0x1000);
sysbus_init_mmio(sbd, &s->iomem);
sysbus_init_irq(sbd, &s->irq);
}
static void sse_timer_realize(DeviceState *dev, Error **errp)
{
SSETimer *s = SSE_TIMER(dev);
if (!s->counter) {
error_setg(errp, "counter property was not set");
return;
}
s->counter_notifier.notify = sse_timer_counter_callback;
sse_counter_register_consumer(s->counter, &s->counter_notifier);
timer_init_ns(&s->timer, QEMU_CLOCK_VIRTUAL, sse_timer_cb, s);
}
static const VMStateDescription sse_timer_vmstate = {
.name = "sse-timer",
.version_id = 1,
.minimum_version_id = 1,
.fields = (VMStateField[]) {
VMSTATE_TIMER(timer, SSETimer),
VMSTATE_UINT32(cntfrq, SSETimer),
VMSTATE_UINT32(cntp_ctl, SSETimer),
VMSTATE_UINT64(cntp_cval, SSETimer),
VMSTATE_UINT64(cntp_aival, SSETimer),
VMSTATE_UINT32(cntp_aival_ctl, SSETimer),
VMSTATE_UINT32(cntp_aival_reload, SSETimer),
VMSTATE_END_OF_LIST()
}
};
static Property sse_timer_properties[] = {
DEFINE_PROP_LINK("counter", SSETimer, counter, TYPE_SSE_COUNTER, SSECounter *),
DEFINE_PROP_END_OF_LIST(),
};
static void sse_timer_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
dc->realize = sse_timer_realize;
dc->vmsd = &sse_timer_vmstate;
dc->reset = sse_timer_reset;
device_class_set_props(dc, sse_timer_properties);
}
static const TypeInfo sse_timer_info = {
.name = TYPE_SSE_TIMER,
.parent = TYPE_SYS_BUS_DEVICE,
.instance_size = sizeof(SSETimer),
.instance_init = sse_timer_init,
.class_init = sse_timer_class_init,
};
static void sse_timer_register_types(void)
{
type_register_static(&sse_timer_info);
}
type_init(sse_timer_register_types);
