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qemu/hw/timer/imx_epit.c
Axel Heider 7719419deb target/imx: reload cmp timer outside of the reload ptimer transaction 
When running seL4 tests (https://docs.sel4.systems/projects/sel4test)
on the sabrelight platform, the timer tests fail. The arm/imx6 EPIT
timer interrupt does not fire properly, instead of a e.g. second in
can take up to a minute to finally see the interrupt.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1263

Signed-off-by: Axel Heider <axel.heider@hensoldt.net>
Message-id: 166663118138.13362.1229967229046092876-0@git.sr.ht
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2022-10-27 10:27:23 +01:00

383 lines
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/*
* IMX EPIT Timer
*
* Copyright (c) 2008 OK Labs
* Copyright (c) 2011 NICTA Pty Ltd
* Originally written by Hans Jiang
* Updated by Peter Chubb
* Updated by Jean-Christophe Dubois <jcd@tribudubois.net>
*
* This code is licensed under GPL version 2 or later. See
* the COPYING file in the top-level directory.
*
*/
#include "qemu/osdep.h"
#include "hw/timer/imx_epit.h"
#include "migration/vmstate.h"
#include "hw/irq.h"
#include "hw/misc/imx_ccm.h"
#include "qemu/module.h"
#include "qemu/log.h"
#ifndef DEBUG_IMX_EPIT
#define DEBUG_IMX_EPIT 0
#endif
#define DPRINTF(fmt, args...) \
do { \
if (DEBUG_IMX_EPIT) { \
fprintf(stderr, "[%s]%s: " fmt , TYPE_IMX_EPIT, \
__func__, ##args); \
} \
} while (0)
static const char *imx_epit_reg_name(uint32_t reg)
{
switch (reg) {
case 0:
return "CR";
case 1:
return "SR";
case 2:
return "LR";
case 3:
return "CMP";
case 4:
return "CNT";
default:
return "[?]";
}
}
/*
* Exact clock frequencies vary from board to board.
* These are typical.
*/
static const IMXClk imx_epit_clocks[] = {
CLK_NONE, /* 00 disabled */
CLK_IPG, /* 01 ipg_clk, ~532MHz */
CLK_IPG_HIGH, /* 10 ipg_clk_highfreq */
CLK_32k, /* 11 ipg_clk_32k -- ~32kHz */
};
/*
* Update interrupt status
*/
static void imx_epit_update_int(IMXEPITState *s)
{
if (s->sr && (s->cr & CR_OCIEN) && (s->cr & CR_EN)) {
qemu_irq_raise(s->irq);
} else {
qemu_irq_lower(s->irq);
}
}
/*
* Must be called from within a ptimer_transaction_begin/commit block
* for both s->timer_cmp and s->timer_reload.
*/
static void imx_epit_set_freq(IMXEPITState *s)
{
uint32_t clksrc;
uint32_t prescaler;
clksrc = extract32(s->cr, CR_CLKSRC_SHIFT, 2);
prescaler = 1 + extract32(s->cr, CR_PRESCALE_SHIFT, 12);
s->freq = imx_ccm_get_clock_frequency(s->ccm,
imx_epit_clocks[clksrc]) / prescaler;
DPRINTF("Setting ptimer frequency to %u\n", s->freq);
if (s->freq) {
ptimer_set_freq(s->timer_reload, s->freq);
ptimer_set_freq(s->timer_cmp, s->freq);
}
}
static void imx_epit_reset(DeviceState *dev)
{
IMXEPITState *s = IMX_EPIT(dev);
/*
* Soft reset doesn't touch some bits; hard reset clears them
*/
s->cr &= (CR_EN|CR_ENMOD|CR_STOPEN|CR_DOZEN|CR_WAITEN|CR_DBGEN);
s->sr = 0;
s->lr = EPIT_TIMER_MAX;
s->cmp = 0;
s->cnt = 0;
ptimer_transaction_begin(s->timer_cmp);
ptimer_transaction_begin(s->timer_reload);
/* stop both timers */
ptimer_stop(s->timer_cmp);
ptimer_stop(s->timer_reload);
/* compute new frequency */
imx_epit_set_freq(s);
/* init both timers to EPIT_TIMER_MAX */
ptimer_set_limit(s->timer_cmp, EPIT_TIMER_MAX, 1);
ptimer_set_limit(s->timer_reload, EPIT_TIMER_MAX, 1);
if (s->freq && (s->cr & CR_EN)) {
/* if the timer is still enabled, restart it */
ptimer_run(s->timer_reload, 0);
}
ptimer_transaction_commit(s->timer_cmp);
ptimer_transaction_commit(s->timer_reload);
}
static uint32_t imx_epit_update_count(IMXEPITState *s)
{
s->cnt = ptimer_get_count(s->timer_reload);
return s->cnt;
}
static uint64_t imx_epit_read(void *opaque, hwaddr offset, unsigned size)
{
IMXEPITState *s = IMX_EPIT(opaque);
uint32_t reg_value = 0;
switch (offset >> 2) {
case 0: /* Control Register */
reg_value = s->cr;
break;
case 1: /* Status Register */
reg_value = s->sr;
break;
case 2: /* LR - ticks*/
reg_value = s->lr;
break;
case 3: /* CMP */
reg_value = s->cmp;
break;
case 4: /* CNT */
imx_epit_update_count(s);
reg_value = s->cnt;
break;
default:
qemu_log_mask(LOG_GUEST_ERROR, "[%s]%s: Bad register at offset 0x%"
HWADDR_PRIx "\n", TYPE_IMX_EPIT, __func__, offset);
break;
}
DPRINTF("(%s) = 0x%08x\n", imx_epit_reg_name(offset >> 2), reg_value);
return reg_value;
}
/* Must be called from ptimer_transaction_begin/commit block for s->timer_cmp */
static void imx_epit_reload_compare_timer(IMXEPITState *s)
{
if ((s->cr & (CR_EN | CR_OCIEN)) == (CR_EN | CR_OCIEN)) {
/* if the compare feature is on and timers are running */
uint32_t tmp = imx_epit_update_count(s);
uint64_t next;
if (tmp > s->cmp) {
/* It'll fire in this round of the timer */
next = tmp - s->cmp;
} else { /* catch it next time around */
next = tmp - s->cmp + ((s->cr & CR_RLD) ? EPIT_TIMER_MAX : s->lr);
}
ptimer_set_count(s->timer_cmp, next);
}
}
static void imx_epit_write(void *opaque, hwaddr offset, uint64_t value,
unsigned size)
{
IMXEPITState *s = IMX_EPIT(opaque);
uint64_t oldcr;
DPRINTF("(%s, value = 0x%08x)\n", imx_epit_reg_name(offset >> 2),
(uint32_t)value);
switch (offset >> 2) {
case 0: /* CR */
oldcr = s->cr;
s->cr = value & 0x03ffffff;
if (s->cr & CR_SWR) {
/* handle the reset */
imx_epit_reset(DEVICE(s));
/*
* TODO: could we 'break' here? following operations appear
* to duplicate the work imx_epit_reset() already did.
*/
}
ptimer_transaction_begin(s->timer_cmp);
ptimer_transaction_begin(s->timer_reload);
if (!(s->cr & CR_SWR)) {
imx_epit_set_freq(s);
}
if (s->freq && (s->cr & CR_EN) && !(oldcr & CR_EN)) {
if (s->cr & CR_ENMOD) {
if (s->cr & CR_RLD) {
ptimer_set_limit(s->timer_reload, s->lr, 1);
ptimer_set_limit(s->timer_cmp, s->lr, 1);
} else {
ptimer_set_limit(s->timer_reload, EPIT_TIMER_MAX, 1);
ptimer_set_limit(s->timer_cmp, EPIT_TIMER_MAX, 1);
}
}
imx_epit_reload_compare_timer(s);
ptimer_run(s->timer_reload, 0);
if (s->cr & CR_OCIEN) {
ptimer_run(s->timer_cmp, 0);
} else {
ptimer_stop(s->timer_cmp);
}
} else if (!(s->cr & CR_EN)) {
/* stop both timers */
ptimer_stop(s->timer_reload);
ptimer_stop(s->timer_cmp);
} else if (s->cr & CR_OCIEN) {
if (!(oldcr & CR_OCIEN)) {
imx_epit_reload_compare_timer(s);
ptimer_run(s->timer_cmp, 0);
}
} else {
ptimer_stop(s->timer_cmp);
}
ptimer_transaction_commit(s->timer_cmp);
ptimer_transaction_commit(s->timer_reload);
break;
case 1: /* SR - ACK*/
/* writing 1 to OCIF clear the OCIF bit */
if (value & 0x01) {
s->sr = 0;
imx_epit_update_int(s);
}
break;
case 2: /* LR - set ticks */
s->lr = value;
ptimer_transaction_begin(s->timer_cmp);
ptimer_transaction_begin(s->timer_reload);
if (s->cr & CR_RLD) {
/* Also set the limit if the LRD bit is set */
/* If IOVW bit is set then set the timer value */
ptimer_set_limit(s->timer_reload, s->lr, s->cr & CR_IOVW);
ptimer_set_limit(s->timer_cmp, s->lr, 0);
} else if (s->cr & CR_IOVW) {
/* If IOVW bit is set then set the timer value */
ptimer_set_count(s->timer_reload, s->lr);
}
/*
* Commit the change to s->timer_reload, so it can propagate. Otherwise
* the timer interrupt may not fire properly. The commit must happen
* before calling imx_epit_reload_compare_timer(), which reads
* s->timer_reload internally again.
*/
ptimer_transaction_commit(s->timer_reload);
imx_epit_reload_compare_timer(s);
ptimer_transaction_commit(s->timer_cmp);
break;
case 3: /* CMP */
s->cmp = value;
ptimer_transaction_begin(s->timer_cmp);
imx_epit_reload_compare_timer(s);
ptimer_transaction_commit(s->timer_cmp);
break;
default:
qemu_log_mask(LOG_GUEST_ERROR, "[%s]%s: Bad register at offset 0x%"
HWADDR_PRIx "\n", TYPE_IMX_EPIT, __func__, offset);
break;
}
}
static void imx_epit_cmp(void *opaque)
{
IMXEPITState *s = IMX_EPIT(opaque);
DPRINTF("sr was %d\n", s->sr);
s->sr = 1;
imx_epit_update_int(s);
}
static void imx_epit_reload(void *opaque)
{
/* No action required on rollover of timer_reload */
}
static const MemoryRegionOps imx_epit_ops = {
.read = imx_epit_read,
.write = imx_epit_write,
.endianness = DEVICE_NATIVE_ENDIAN,
};
static const VMStateDescription vmstate_imx_timer_epit = {
.name = TYPE_IMX_EPIT,
.version_id = 2,
.minimum_version_id = 2,
.fields = (VMStateField[]) {
VMSTATE_UINT32(cr, IMXEPITState),
VMSTATE_UINT32(sr, IMXEPITState),
VMSTATE_UINT32(lr, IMXEPITState),
VMSTATE_UINT32(cmp, IMXEPITState),
VMSTATE_UINT32(cnt, IMXEPITState),
VMSTATE_UINT32(freq, IMXEPITState),
VMSTATE_PTIMER(timer_reload, IMXEPITState),
VMSTATE_PTIMER(timer_cmp, IMXEPITState),
VMSTATE_END_OF_LIST()
}
};
static void imx_epit_realize(DeviceState *dev, Error **errp)
{
IMXEPITState *s = IMX_EPIT(dev);
SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
DPRINTF("\n");
sysbus_init_irq(sbd, &s->irq);
memory_region_init_io(&s->iomem, OBJECT(s), &imx_epit_ops, s, TYPE_IMX_EPIT,
0x00001000);
sysbus_init_mmio(sbd, &s->iomem);
s->timer_reload = ptimer_init(imx_epit_reload, s, PTIMER_POLICY_LEGACY);
s->timer_cmp = ptimer_init(imx_epit_cmp, s, PTIMER_POLICY_LEGACY);
}
static void imx_epit_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
dc->realize = imx_epit_realize;
dc->reset = imx_epit_reset;
dc->vmsd = &vmstate_imx_timer_epit;
dc->desc = "i.MX periodic timer";
}
static const TypeInfo imx_epit_info = {
.name = TYPE_IMX_EPIT,
.parent = TYPE_SYS_BUS_DEVICE,
.instance_size = sizeof(IMXEPITState),
.class_init = imx_epit_class_init,
};
static void imx_epit_register_types(void)
{
type_register_static(&imx_epit_info);
}
type_init(imx_epit_register_types)
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