| Message ID | 20200921035257.434532-5-f4bug@amsat.org |
|---|---|
| State | Superseded |
| Headers | show |
| Series | hw/arm/raspi: Fix SYS_timer to unbrick Linux kernels v3.7+ | expand |
Hi Phil, On 9/21/20 5:52 AM, Philippe Mathieu-Daudé wrote: > This peripheral has 1 free-running timer and 4 compare registers. > > Only the free-running timer is implemented. Add support the > COMPARE registers (each register is wired to an IRQ). > > Reference: "BCM2835 ARM Peripherals" datasheet [*] > chapter 12 "System Timer": > > The System Timer peripheral provides four 32-bit timer channels > and a single 64-bit free running counter. Each channel has an > output compare register, which is compared against the 32 least > significant bits of the free running counter values. When the > two values match, the system timer peripheral generates a signal > to indicate a match for the appropriate channel. The match signal > is then fed into the interrupt controller. > > This peripheral is used since Linux 3.7, commit ee4af5696720 > ("ARM: bcm2835: add system timer"). > > [*] https://www.raspberrypi.org/app/uploads/2012/02/BCM2835-ARM-Peripherals.pdf > > Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org> > --- > include/hw/timer/bcm2835_systmr.h | 11 +++++++-- > hw/timer/bcm2835_systmr.c | 41 +++++++++++++++++++------------ > hw/timer/trace-events | 4 ++- > 3 files changed, 37 insertions(+), 19 deletions(-) > > diff --git a/include/hw/timer/bcm2835_systmr.h b/include/hw/timer/bcm2835_systmr.h > index e0db9e9e12b..17fdd9d67b2 100644 > --- a/include/hw/timer/bcm2835_systmr.h > +++ b/include/hw/timer/bcm2835_systmr.h > @@ -11,6 +11,7 @@ > > #include "hw/sysbus.h" > #include "hw/irq.h" > +#include "qemu/timer.h" > #include "qom/object.h" > > #define TYPE_BCM2835_SYSTIMER "bcm2835-sys-timer" > @@ -20,18 +21,24 @@ DECLARE_INSTANCE_CHECKER(BCM2835SystemTimerState, BCM2835_SYSTIMER, > > #define BCM2835_SYSTIMER_COUNT 4 > > +typedef struct { > + unsigned id; > + QEMUTimer timer; > + qemu_irq irq; > + BCM2835SystemTimerState *state; > +} BCM2835SystemTimerCompare; > + > struct BCM2835SystemTimerState { > /*< private >*/ > SysBusDevice parent_obj; > > /*< public >*/ > MemoryRegion iomem; > - qemu_irq irq; > - > struct { > uint32_t ctrl_status; > uint32_t compare[BCM2835_SYSTIMER_COUNT]; > } reg; > + BCM2835SystemTimerCompare tmr[BCM2835_SYSTIMER_COUNT]; > }; > > #endif > diff --git a/hw/timer/bcm2835_systmr.c b/hw/timer/bcm2835_systmr.c > index b234e83824f..43e644f5e45 100644 > --- a/hw/timer/bcm2835_systmr.c > +++ b/hw/timer/bcm2835_systmr.c > @@ -28,20 +28,13 @@ REG32(COMPARE1, 0x10) > REG32(COMPARE2, 0x14) > REG32(COMPARE3, 0x18) > > -static void bcm2835_systmr_update_irq(BCM2835SystemTimerState *s) > +static void bcm2835_systmr_timer_expire(void *opaque) > { > - bool enable = !!s->reg.ctrl_status; > + BCM2835SystemTimerCompare *tmr = opaque; > > - trace_bcm2835_systmr_irq(enable); > - qemu_set_irq(s->irq, enable); > -} > - > -static void bcm2835_systmr_update_compare(BCM2835SystemTimerState *s, > - unsigned timer_index) > -{ > - /* TODO fow now, since neither Linux nor U-boot use these timers. */ > - qemu_log_mask(LOG_UNIMP, "COMPARE register %u not implemented\n", > - timer_index); > + trace_bcm2835_systmr_timer_expired(tmr->id); > + tmr->state->reg.ctrl_status |= 1 << tmr->id; > + qemu_set_irq(tmr->irq, 1); > } > > static uint64_t bcm2835_systmr_read(void *opaque, hwaddr offset, > @@ -78,16 +71,25 @@ static void bcm2835_systmr_write(void *opaque, hwaddr offset, > uint64_t value, unsigned size) > { > BCM2835SystemTimerState *s = BCM2835_SYSTIMER(opaque); > + int index; > > trace_bcm2835_systmr_write(offset, value); > switch (offset) { > case A_CTRL_STATUS: > s->reg.ctrl_status &= ~value; /* Ack */ > - bcm2835_systmr_update_irq(s); > + for (index = 0; index < ARRAY_SIZE(s->tmr); index++) { > + if (extract32(value, index, 1)) { > + trace_bcm2835_systmr_irq_ack(index); > + qemu_set_irq(s->tmr[index].irq, 0); > + } > + } > break; > case A_COMPARE0 ... A_COMPARE3: > - s->reg.compare[(offset - A_COMPARE0) >> 2] = value; > - bcm2835_systmr_update_compare(s, (offset - A_COMPARE0) >> 2); > + index = (offset - A_COMPARE0) >> 2; > + s->reg.compare[index] = value; > + timer_mod(&s->tmr[index].timer, value); I think "value" is wrong here. timer_mod takes an absolute time value. Here "value" is a 32 bits truncated view of "current_time + some_time". > + trace_bcm2835_systmr_run(index, > + value - qemu_clock_get_us(QEMU_CLOCK_VIRTUAL)); Here also. I think you can do something like (untested): { uint64_t now, triggers_at; uint32_t clo, triggers_in; index = (offset - A_COMPARE0) >> 2; s->reg.compare[index] = value; /* get the current clock and its truncated 32 bits view */ now = qemu_clock_get_us(QEMU_CLOCK_VIRTUAL); clo = now; /* will overflow in case clo > value. We still get the correct value on 32 bits (which is "UINT32_MAX - (clo - value)") */ triggers_in = value - clo; /* timer_mod takes an absolute time value, go back to 64 bits values */ triggers_at = now + triggers_in; timer_mod(&s->tmr[index].timer, triggers_at); trace_bcm2835_systmr_run(index, triggers_in); } The rest is OK to me.
On 9/21/20 9:39 PM, Luc Michel wrote: > Hi Phil, > > On 9/21/20 5:52 AM, Philippe Mathieu-Daudé wrote: >> This peripheral has 1 free-running timer and 4 compare registers. >> >> Only the free-running timer is implemented. Add support the >> COMPARE registers (each register is wired to an IRQ). >> >> Reference: "BCM2835 ARM Peripherals" datasheet [*] >> chapter 12 "System Timer": >> >> The System Timer peripheral provides four 32-bit timer channels >> and a single 64-bit free running counter. Each channel has an >> output compare register, which is compared against the 32 least >> significant bits of the free running counter values. When the >> two values match, the system timer peripheral generates a signal >> to indicate a match for the appropriate channel. The match signal >> is then fed into the interrupt controller. >> >> This peripheral is used since Linux 3.7, commit ee4af5696720 >> ("ARM: bcm2835: add system timer"). >> >> [*] >> https://www.raspberrypi.org/app/uploads/2012/02/BCM2835-ARM-Peripherals.pdf >> >> >> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org> >> --- >> include/hw/timer/bcm2835_systmr.h | 11 +++++++-- >> hw/timer/bcm2835_systmr.c | 41 +++++++++++++++++++------------ >> hw/timer/trace-events | 4 ++- >> 3 files changed, 37 insertions(+), 19 deletions(-) >> >> diff --git a/include/hw/timer/bcm2835_systmr.h >> b/include/hw/timer/bcm2835_systmr.h >> index e0db9e9e12b..17fdd9d67b2 100644 >> --- a/include/hw/timer/bcm2835_systmr.h >> +++ b/include/hw/timer/bcm2835_systmr.h >> @@ -11,6 +11,7 @@ >> #include "hw/sysbus.h" >> #include "hw/irq.h" >> +#include "qemu/timer.h" >> #include "qom/object.h" >> #define TYPE_BCM2835_SYSTIMER "bcm2835-sys-timer" >> @@ -20,18 +21,24 @@ DECLARE_INSTANCE_CHECKER(BCM2835SystemTimerState, >> BCM2835_SYSTIMER, >> #define BCM2835_SYSTIMER_COUNT 4 >> +typedef struct { >> + unsigned id; >> + QEMUTimer timer; >> + qemu_irq irq; >> + BCM2835SystemTimerState *state; >> +} BCM2835SystemTimerCompare; >> + >> struct BCM2835SystemTimerState { >> /*< private >*/ >> SysBusDevice parent_obj; >> /*< public >*/ >> MemoryRegion iomem; >> - qemu_irq irq; >> - >> struct { >> uint32_t ctrl_status; >> uint32_t compare[BCM2835_SYSTIMER_COUNT]; >> } reg; >> + BCM2835SystemTimerCompare tmr[BCM2835_SYSTIMER_COUNT]; >> }; >> #endif >> diff --git a/hw/timer/bcm2835_systmr.c b/hw/timer/bcm2835_systmr.c >> index b234e83824f..43e644f5e45 100644 >> --- a/hw/timer/bcm2835_systmr.c >> +++ b/hw/timer/bcm2835_systmr.c >> @@ -28,20 +28,13 @@ REG32(COMPARE1, 0x10) >> REG32(COMPARE2, 0x14) >> REG32(COMPARE3, 0x18) >> -static void bcm2835_systmr_update_irq(BCM2835SystemTimerState *s) >> +static void bcm2835_systmr_timer_expire(void *opaque) >> { >> - bool enable = !!s->reg.ctrl_status; >> + BCM2835SystemTimerCompare *tmr = opaque; >> - trace_bcm2835_systmr_irq(enable); >> - qemu_set_irq(s->irq, enable); >> -} >> - >> -static void bcm2835_systmr_update_compare(BCM2835SystemTimerState *s, >> - unsigned timer_index) >> -{ >> - /* TODO fow now, since neither Linux nor U-boot use these timers. */ >> - qemu_log_mask(LOG_UNIMP, "COMPARE register %u not implemented\n", >> - timer_index); >> + trace_bcm2835_systmr_timer_expired(tmr->id); >> + tmr->state->reg.ctrl_status |= 1 << tmr->id; >> + qemu_set_irq(tmr->irq, 1); >> } >> static uint64_t bcm2835_systmr_read(void *opaque, hwaddr offset, >> @@ -78,16 +71,25 @@ static void bcm2835_systmr_write(void *opaque, >> hwaddr offset, >> uint64_t value, unsigned size) >> { >> BCM2835SystemTimerState *s = BCM2835_SYSTIMER(opaque); >> + int index; >> trace_bcm2835_systmr_write(offset, value); >> switch (offset) { >> case A_CTRL_STATUS: >> s->reg.ctrl_status &= ~value; /* Ack */ >> - bcm2835_systmr_update_irq(s); >> + for (index = 0; index < ARRAY_SIZE(s->tmr); index++) { >> + if (extract32(value, index, 1)) { >> + trace_bcm2835_systmr_irq_ack(index); >> + qemu_set_irq(s->tmr[index].irq, 0); >> + } >> + } >> break; >> case A_COMPARE0 ... A_COMPARE3: >> - s->reg.compare[(offset - A_COMPARE0) >> 2] = value; >> - bcm2835_systmr_update_compare(s, (offset - A_COMPARE0) >> 2); >> + index = (offset - A_COMPARE0) >> 2; >> + s->reg.compare[index] = value; >> + timer_mod(&s->tmr[index].timer, value); > > I think "value" is wrong here. timer_mod takes an absolute time value. > Here "value" is a 32 bits truncated view of "current_time + some_time". Yes, you are correct. The reduced datasheet is not easy to understand. >> + trace_bcm2835_systmr_run(index, >> + value - >> qemu_clock_get_us(QEMU_CLOCK_VIRTUAL)); > Here also. > > I think you can do something like (untested): > { > uint64_t now, triggers_at; > uint32_t clo, triggers_in; > > index = (offset - A_COMPARE0) >> 2; > s->reg.compare[index] = value; > > /* get the current clock and its truncated 32 bits view */ > now = qemu_clock_get_us(QEMU_CLOCK_VIRTUAL); > clo = now; > > /* will overflow in case clo > value. We still get the > correct value on 32 bits (which is "UINT32_MAX - (clo - value)") */ > triggers_in = value - clo; > > /* timer_mod takes an absolute time value, go back to 64 > bits values */ > triggers_at = now + triggers_in; > timer_mod(&s->tmr[index].timer, triggers_at); > > trace_bcm2835_systmr_run(index, triggers_in); This matches the datasheet description, thanks! > } > > > The rest is OK to me. >
diff --git a/include/hw/timer/bcm2835_systmr.h b/include/hw/timer/bcm2835_systmr.h index e0db9e9e12b..17fdd9d67b2 100644 --- a/include/hw/timer/bcm2835_systmr.h +++ b/include/hw/timer/bcm2835_systmr.h @@ -11,6 +11,7 @@ #include "hw/sysbus.h" #include "hw/irq.h" +#include "qemu/timer.h" #include "qom/object.h" #define TYPE_BCM2835_SYSTIMER "bcm2835-sys-timer" @@ -20,18 +21,24 @@ DECLARE_INSTANCE_CHECKER(BCM2835SystemTimerState, BCM2835_SYSTIMER, #define BCM2835_SYSTIMER_COUNT 4 +typedef struct { + unsigned id; + QEMUTimer timer; + qemu_irq irq; + BCM2835SystemTimerState *state; +} BCM2835SystemTimerCompare; + struct BCM2835SystemTimerState { /*< private >*/ SysBusDevice parent_obj; /*< public >*/ MemoryRegion iomem; - qemu_irq irq; - struct { uint32_t ctrl_status; uint32_t compare[BCM2835_SYSTIMER_COUNT]; } reg; + BCM2835SystemTimerCompare tmr[BCM2835_SYSTIMER_COUNT]; }; #endif diff --git a/hw/timer/bcm2835_systmr.c b/hw/timer/bcm2835_systmr.c index b234e83824f..43e644f5e45 100644 --- a/hw/timer/bcm2835_systmr.c +++ b/hw/timer/bcm2835_systmr.c @@ -28,20 +28,13 @@ REG32(COMPARE1, 0x10) REG32(COMPARE2, 0x14) REG32(COMPARE3, 0x18) -static void bcm2835_systmr_update_irq(BCM2835SystemTimerState *s) +static void bcm2835_systmr_timer_expire(void *opaque) { - bool enable = !!s->reg.ctrl_status; + BCM2835SystemTimerCompare *tmr = opaque; - trace_bcm2835_systmr_irq(enable); - qemu_set_irq(s->irq, enable); -} - -static void bcm2835_systmr_update_compare(BCM2835SystemTimerState *s, - unsigned timer_index) -{ - /* TODO fow now, since neither Linux nor U-boot use these timers. */ - qemu_log_mask(LOG_UNIMP, "COMPARE register %u not implemented\n", - timer_index); + trace_bcm2835_systmr_timer_expired(tmr->id); + tmr->state->reg.ctrl_status |= 1 << tmr->id; + qemu_set_irq(tmr->irq, 1); } static uint64_t bcm2835_systmr_read(void *opaque, hwaddr offset, @@ -78,16 +71,25 @@ static void bcm2835_systmr_write(void *opaque, hwaddr offset, uint64_t value, unsigned size) { BCM2835SystemTimerState *s = BCM2835_SYSTIMER(opaque); + int index; trace_bcm2835_systmr_write(offset, value); switch (offset) { case A_CTRL_STATUS: s->reg.ctrl_status &= ~value; /* Ack */ - bcm2835_systmr_update_irq(s); + for (index = 0; index < ARRAY_SIZE(s->tmr); index++) { + if (extract32(value, index, 1)) { + trace_bcm2835_systmr_irq_ack(index); + qemu_set_irq(s->tmr[index].irq, 0); + } + } break; case A_COMPARE0 ... A_COMPARE3: - s->reg.compare[(offset - A_COMPARE0) >> 2] = value; - bcm2835_systmr_update_compare(s, (offset - A_COMPARE0) >> 2); + index = (offset - A_COMPARE0) >> 2; + s->reg.compare[index] = value; + timer_mod(&s->tmr[index].timer, value); + trace_bcm2835_systmr_run(index, + value - qemu_clock_get_us(QEMU_CLOCK_VIRTUAL)); break; case A_COUNTER_LOW: case A_COUNTER_HIGH: @@ -125,7 +127,14 @@ static void bcm2835_systmr_realize(DeviceState *dev, Error **errp) memory_region_init_io(&s->iomem, OBJECT(dev), &bcm2835_systmr_ops, s, "bcm2835-sys-timer", 0x20); sysbus_init_mmio(SYS_BUS_DEVICE(dev), &s->iomem); - sysbus_init_irq(SYS_BUS_DEVICE(dev), &s->irq); + + for (size_t i = 0; i < ARRAY_SIZE(s->tmr); i++) { + s->tmr[i].id = i; + s->tmr[i].state = s; + sysbus_init_irq(SYS_BUS_DEVICE(dev), &s->tmr[i].irq); + timer_init_us(&s->tmr[i].timer, QEMU_CLOCK_VIRTUAL, + bcm2835_systmr_timer_expire, &s->tmr[i]); + } } static const VMStateDescription bcm2835_systmr_vmstate = { diff --git a/hw/timer/trace-events b/hw/timer/trace-events index b996d992000..f4ca31d4951 100644 --- a/hw/timer/trace-events +++ b/hw/timer/trace-events @@ -77,9 +77,11 @@ nrf51_timer_write(uint8_t timer_id, uint64_t addr, uint32_t value, unsigned size nrf51_timer_set_count(uint8_t timer_id, uint8_t counter_id, uint32_t value) "timer %u counter %u count 0x%" PRIx32 # bcm2835_systmr.c -bcm2835_systmr_irq(bool enable) "timer irq state %u" +bcm2835_systmr_timer_expired(unsigned id) "timer #%u expired" +bcm2835_systmr_irq_ack(unsigned id) "timer #%u acked" bcm2835_systmr_read(uint64_t offset, uint64_t data) "timer read: offset 0x%" PRIx64 " data 0x%" PRIx64 bcm2835_systmr_write(uint64_t offset, uint64_t data) "timer write: offset 0x%" PRIx64 " data 0x%" PRIx64 +bcm2835_systmr_run(unsigned id, uint64_t delay_us) "timer #%u expiring in %"PRIu64" us" # avr_timer16.c avr_timer16_read(uint8_t addr, uint8_t value) "timer16 read addr:%u value:%u"
This peripheral has 1 free-running timer and 4 compare registers. Only the free-running timer is implemented. Add support the COMPARE registers (each register is wired to an IRQ). Reference: "BCM2835 ARM Peripherals" datasheet [*] chapter 12 "System Timer": The System Timer peripheral provides four 32-bit timer channels and a single 64-bit free running counter. Each channel has an output compare register, which is compared against the 32 least significant bits of the free running counter values. When the two values match, the system timer peripheral generates a signal to indicate a match for the appropriate channel. The match signal is then fed into the interrupt controller. This peripheral is used since Linux 3.7, commit ee4af5696720 ("ARM: bcm2835: add system timer"). [*] https://www.raspberrypi.org/app/uploads/2012/02/BCM2835-ARM-Peripherals.pdf Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org> --- include/hw/timer/bcm2835_systmr.h | 11 +++++++-- hw/timer/bcm2835_systmr.c | 41 +++++++++++++++++++------------ hw/timer/trace-events | 4 ++- 3 files changed, 37 insertions(+), 19 deletions(-)