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hw/watchdog: Implement full i.MX watchdog support
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Implement full support for the watchdog in i.MX systems.
Pretimeout support is optional because the watchdog hardware
on i.MX31 does not support pretimeouts.

Signed-off-by: Guenter Roeck <[email protected]>
Message-id: [email protected]
Signed-off-by: Peter Maydell <[email protected]>
[PMM: added Property array terminator entry]
Reviewed-by: Peter Maydell <[email protected]>
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@groeck @pm215
groeck authored and pm215 committed May 21, 2020
1 parent 37f9595 commit daca13d
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Showing 2 changed files with 285 additions and 14 deletions.
238 changes: 226 additions & 12 deletions hw/watchdog/wdt_imx2.c
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Original file line number Diff line number Diff line change
Expand Up @@ -13,24 +13,189 @@
#include "qemu/bitops.h"
#include "qemu/module.h"
#include "sysemu/watchdog.h"
#include "migration/vmstate.h"
#include "hw/qdev-properties.h"

#include "hw/watchdog/wdt_imx2.h"

#define IMX2_WDT_WCR_WDA BIT(5) /* -> External Reset WDOG_B */
#define IMX2_WDT_WCR_SRS BIT(4) /* -> Software Reset Signal */
static void imx2_wdt_interrupt(void *opaque)
{
IMX2WdtState *s = IMX2_WDT(opaque);

s->wicr |= IMX2_WDT_WICR_WTIS;
qemu_set_irq(s->irq, 1);
}

static void imx2_wdt_expired(void *opaque)
{
IMX2WdtState *s = IMX2_WDT(opaque);

s->wrsr = IMX2_WDT_WRSR_TOUT;

/* Perform watchdog action if watchdog is enabled */
if (s->wcr & IMX2_WDT_WCR_WDE) {
s->wrsr = IMX2_WDT_WRSR_TOUT;
watchdog_perform_action();
}
}

static void imx2_wdt_reset(DeviceState *dev)
{
IMX2WdtState *s = IMX2_WDT(dev);

ptimer_transaction_begin(s->timer);
ptimer_stop(s->timer);
ptimer_transaction_commit(s->timer);

if (s->pretimeout_support) {
ptimer_transaction_begin(s->itimer);
ptimer_stop(s->itimer);
ptimer_transaction_commit(s->itimer);
}

s->wicr_locked = false;
s->wcr_locked = false;
s->wcr_wde_locked = false;

s->wcr = IMX2_WDT_WCR_WDA | IMX2_WDT_WCR_SRS;
s->wsr = 0;
s->wrsr &= ~(IMX2_WDT_WRSR_TOUT | IMX2_WDT_WRSR_SFTW);
s->wicr = IMX2_WDT_WICR_WICT_DEF;
s->wmcr = IMX2_WDT_WMCR_PDE;
}

static uint64_t imx2_wdt_read(void *opaque, hwaddr addr,
unsigned int size)
static uint64_t imx2_wdt_read(void *opaque, hwaddr addr, unsigned int size)
{
IMX2WdtState *s = IMX2_WDT(opaque);

switch (addr) {
case IMX2_WDT_WCR:
return s->wcr;
case IMX2_WDT_WSR:
return s->wsr;
case IMX2_WDT_WRSR:
return s->wrsr;
case IMX2_WDT_WICR:
return s->wicr;
case IMX2_WDT_WMCR:
return s->wmcr;
}
return 0;
}

static void imx_wdt2_update_itimer(IMX2WdtState *s, bool start)
{
bool running = (s->wcr & IMX2_WDT_WCR_WDE) && (s->wcr & IMX2_WDT_WCR_WT);
bool enabled = s->wicr & IMX2_WDT_WICR_WIE;

ptimer_transaction_begin(s->itimer);
if (start || !enabled) {
ptimer_stop(s->itimer);
}
if (running && enabled) {
int count = ptimer_get_count(s->timer);
int pretimeout = s->wicr & IMX2_WDT_WICR_WICT;

/*
* Only (re-)start pretimeout timer if its counter value is larger
* than 0. Otherwise it will fire right away and we'll get an
* interrupt loop.
*/
if (count > pretimeout) {
ptimer_set_count(s->itimer, count - pretimeout);
if (start) {
ptimer_run(s->itimer, 1);
}
}
}
ptimer_transaction_commit(s->itimer);
}

static void imx_wdt2_update_timer(IMX2WdtState *s, bool start)
{
ptimer_transaction_begin(s->timer);
if (start) {
ptimer_stop(s->timer);
}
if ((s->wcr & IMX2_WDT_WCR_WDE) && (s->wcr & IMX2_WDT_WCR_WT)) {
int count = (s->wcr & IMX2_WDT_WCR_WT) >> 8;

/* A value of 0 reflects one period (0.5s). */
ptimer_set_count(s->timer, count + 1);
if (start) {
ptimer_run(s->timer, 1);
}
}
ptimer_transaction_commit(s->timer);
if (s->pretimeout_support) {
imx_wdt2_update_itimer(s, start);
}
}

static void imx2_wdt_write(void *opaque, hwaddr addr,
uint64_t value, unsigned int size)
{
if (addr == IMX2_WDT_WCR &&
(~value & (IMX2_WDT_WCR_WDA | IMX2_WDT_WCR_SRS))) {
watchdog_perform_action();
IMX2WdtState *s = IMX2_WDT(opaque);

switch (addr) {
case IMX2_WDT_WCR:
if (s->wcr_locked) {
value &= ~IMX2_WDT_WCR_LOCK_MASK;
value |= (s->wicr & IMX2_WDT_WCR_LOCK_MASK);
}
s->wcr_locked = true;
if (s->wcr_wde_locked) {
value &= ~IMX2_WDT_WCR_WDE;
value |= (s->wicr & ~IMX2_WDT_WCR_WDE);
} else if (value & IMX2_WDT_WCR_WDE) {
s->wcr_wde_locked = true;
}
if (s->wcr_wdt_locked) {
value &= ~IMX2_WDT_WCR_WDT;
value |= (s->wicr & ~IMX2_WDT_WCR_WDT);
} else if (value & IMX2_WDT_WCR_WDT) {
s->wcr_wdt_locked = true;
}

s->wcr = value;
if (!(value & IMX2_WDT_WCR_SRS)) {
s->wrsr = IMX2_WDT_WRSR_SFTW;
}
if (!(value & (IMX2_WDT_WCR_WDA | IMX2_WDT_WCR_SRS)) ||
(!(value & IMX2_WDT_WCR_WT) && (value & IMX2_WDT_WCR_WDE))) {
watchdog_perform_action();
}
s->wcr |= IMX2_WDT_WCR_SRS;
imx_wdt2_update_timer(s, true);
break;
case IMX2_WDT_WSR:
if (s->wsr == IMX2_WDT_SEQ1 && value == IMX2_WDT_SEQ2) {
imx_wdt2_update_timer(s, false);
}
s->wsr = value;
break;
case IMX2_WDT_WRSR:
break;
case IMX2_WDT_WICR:
if (!s->pretimeout_support) {
return;
}
value &= IMX2_WDT_WICR_LOCK_MASK | IMX2_WDT_WICR_WTIS;
if (s->wicr_locked) {
value &= IMX2_WDT_WICR_WTIS;
value |= (s->wicr & IMX2_WDT_WICR_LOCK_MASK);
}
s->wicr = value | (s->wicr & IMX2_WDT_WICR_WTIS);
if (value & IMX2_WDT_WICR_WTIS) {
s->wicr &= ~IMX2_WDT_WICR_WTIS;
qemu_set_irq(s->irq, 0);
}
imx_wdt2_update_itimer(s, true);
s->wicr_locked = true;
break;
case IMX2_WDT_WMCR:
s->wmcr = value & IMX2_WDT_WMCR_PDE;
break;
}
}

Expand All @@ -45,28 +210,77 @@ static const MemoryRegionOps imx2_wdt_ops = {
* real device but in practice there is no reason for a guest
* to access this device unaligned.
*/
.min_access_size = 4,
.max_access_size = 4,
.min_access_size = 2,
.max_access_size = 2,
.unaligned = false,
},
};

static const VMStateDescription vmstate_imx2_wdt = {
.name = "imx2.wdt",
.fields = (VMStateField[]) {
VMSTATE_PTIMER(timer, IMX2WdtState),
VMSTATE_PTIMER(itimer, IMX2WdtState),
VMSTATE_BOOL(wicr_locked, IMX2WdtState),
VMSTATE_BOOL(wcr_locked, IMX2WdtState),
VMSTATE_BOOL(wcr_wde_locked, IMX2WdtState),
VMSTATE_BOOL(wcr_wdt_locked, IMX2WdtState),
VMSTATE_UINT16(wcr, IMX2WdtState),
VMSTATE_UINT16(wsr, IMX2WdtState),
VMSTATE_UINT16(wrsr, IMX2WdtState),
VMSTATE_UINT16(wmcr, IMX2WdtState),
VMSTATE_UINT16(wicr, IMX2WdtState),
VMSTATE_END_OF_LIST()
}
};

static void imx2_wdt_realize(DeviceState *dev, Error **errp)
{
IMX2WdtState *s = IMX2_WDT(dev);
SysBusDevice *sbd = SYS_BUS_DEVICE(dev);

memory_region_init_io(&s->mmio, OBJECT(dev),
&imx2_wdt_ops, s,
TYPE_IMX2_WDT".mmio",
IMX2_WDT_REG_NUM * sizeof(uint16_t));
sysbus_init_mmio(SYS_BUS_DEVICE(dev), &s->mmio);
TYPE_IMX2_WDT,
IMX2_WDT_MMIO_SIZE);
sysbus_init_mmio(sbd, &s->mmio);
sysbus_init_irq(sbd, &s->irq);

s->timer = ptimer_init(imx2_wdt_expired, s,
PTIMER_POLICY_NO_IMMEDIATE_TRIGGER |
PTIMER_POLICY_NO_IMMEDIATE_RELOAD |
PTIMER_POLICY_NO_COUNTER_ROUND_DOWN);
ptimer_transaction_begin(s->timer);
ptimer_set_freq(s->timer, 2);
ptimer_set_limit(s->timer, 0xff, 1);
ptimer_transaction_commit(s->timer);
if (s->pretimeout_support) {
s->itimer = ptimer_init(imx2_wdt_interrupt, s,
PTIMER_POLICY_NO_IMMEDIATE_TRIGGER |
PTIMER_POLICY_NO_IMMEDIATE_RELOAD |
PTIMER_POLICY_NO_COUNTER_ROUND_DOWN);
ptimer_transaction_begin(s->itimer);
ptimer_set_freq(s->itimer, 2);
ptimer_set_limit(s->itimer, 0xff, 1);
ptimer_transaction_commit(s->itimer);
}
}

static Property imx2_wdt_properties[] = {
DEFINE_PROP_BOOL("pretimeout-support", IMX2WdtState, pretimeout_support,
false),
DEFINE_PROP_END_OF_LIST()
};

static void imx2_wdt_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);

device_class_set_props(dc, imx2_wdt_properties);
dc->realize = imx2_wdt_realize;
dc->reset = imx2_wdt_reset;
dc->vmsd = &vmstate_imx2_wdt;
dc->desc = "i.MX watchdog timer";
set_bit(DEVICE_CATEGORY_MISC, dc->categories);
}

Expand Down
61 changes: 59 additions & 2 deletions include/hw/watchdog/wdt_imx2.h
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Original file line number Diff line number Diff line change
Expand Up @@ -12,22 +12,79 @@
#ifndef IMX2_WDT_H
#define IMX2_WDT_H

#include "qemu/bitops.h"
#include "hw/sysbus.h"
#include "hw/irq.h"
#include "hw/ptimer.h"

#define TYPE_IMX2_WDT "imx2.wdt"
#define IMX2_WDT(obj) OBJECT_CHECK(IMX2WdtState, (obj), TYPE_IMX2_WDT)

enum IMX2WdtRegisters {
IMX2_WDT_WCR = 0x0000,
IMX2_WDT_REG_NUM = 0x0008 / sizeof(uint16_t) + 1,
IMX2_WDT_WCR = 0x0000, /* Control Register */
IMX2_WDT_WSR = 0x0002, /* Service Register */
IMX2_WDT_WRSR = 0x0004, /* Reset Status Register */
IMX2_WDT_WICR = 0x0006, /* Interrupt Control Register */
IMX2_WDT_WMCR = 0x0008, /* Misc Register */
};

#define IMX2_WDT_MMIO_SIZE 0x000a

/* Control Register definitions */
#define IMX2_WDT_WCR_WT (0xFF << 8) /* Watchdog Timeout Field */
#define IMX2_WDT_WCR_WDW BIT(7) /* WDOG Disable for Wait */
#define IMX2_WDT_WCR_WDA BIT(5) /* WDOG Assertion */
#define IMX2_WDT_WCR_SRS BIT(4) /* Software Reset Signal */
#define IMX2_WDT_WCR_WDT BIT(3) /* WDOG Timeout Assertion */
#define IMX2_WDT_WCR_WDE BIT(2) /* Watchdog Enable */
#define IMX2_WDT_WCR_WDBG BIT(1) /* Watchdog Debug Enable */
#define IMX2_WDT_WCR_WDZST BIT(0) /* Watchdog Timer Suspend */

#define IMX2_WDT_WCR_LOCK_MASK (IMX2_WDT_WCR_WDZST | IMX2_WDT_WCR_WDBG \
| IMX2_WDT_WCR_WDW)

/* Service Register definitions */
#define IMX2_WDT_SEQ1 0x5555 /* service sequence 1 */
#define IMX2_WDT_SEQ2 0xAAAA /* service sequence 2 */

/* Reset Status Register definitions */
#define IMX2_WDT_WRSR_TOUT BIT(1) /* Reset due to Timeout */
#define IMX2_WDT_WRSR_SFTW BIT(0) /* Reset due to software reset */

/* Interrupt Control Register definitions */
#define IMX2_WDT_WICR_WIE BIT(15) /* Interrupt Enable */
#define IMX2_WDT_WICR_WTIS BIT(14) /* Interrupt Status */
#define IMX2_WDT_WICR_WICT 0xff /* Interrupt Timeout */
#define IMX2_WDT_WICR_WICT_DEF 0x04 /* Default interrupt timeout (2s) */

#define IMX2_WDT_WICR_LOCK_MASK (IMX2_WDT_WICR_WIE | IMX2_WDT_WICR_WICT)

/* Misc Control Register definitions */
#define IMX2_WDT_WMCR_PDE BIT(0) /* Power-Down Enable */

typedef struct IMX2WdtState {
/* <private> */
SysBusDevice parent_obj;

/*< public >*/
MemoryRegion mmio;
qemu_irq irq;

struct ptimer_state *timer;
struct ptimer_state *itimer;

bool pretimeout_support;
bool wicr_locked;

uint16_t wcr;
uint16_t wsr;
uint16_t wrsr;
uint16_t wicr;
uint16_t wmcr;

bool wcr_locked; /* affects WDZST, WDBG, and WDW */
bool wcr_wde_locked; /* affects WDE */
bool wcr_wdt_locked; /* affects WDT (never cleared) */
} IMX2WdtState;

#endif /* IMX2_WDT_H */

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