diff options
Diffstat (limited to 'hw/timer/armv7m_systick.c')
| -rw-r--r-- | hw/timer/armv7m_systick.c | 124 |
1 files changed, 52 insertions, 72 deletions
diff --git a/hw/timer/armv7m_systick.c b/hw/timer/armv7m_systick.c index a8cec7eb56..2f192011eb 100644 --- a/hw/timer/armv7m_systick.c +++ b/hw/timer/armv7m_systick.c @@ -39,26 +39,6 @@ static inline int64_t systick_scale(SysTickState *s) } } -static void systick_reload(SysTickState *s, int reset) -{ - /* The Cortex-M3 Devices Generic User Guide says that "When the - * ENABLE bit is set to 1, the counter loads the RELOAD value from the - * SYST RVR register and then counts down". So, we need to check the - * ENABLE bit before reloading the value. - */ - trace_systick_reload(); - - if ((s->control & SYSTICK_ENABLE) == 0) { - return; - } - - if (reset) { - s->tick = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); - } - s->tick += (s->reload + 1) * systick_scale(s); - timer_mod(s->timer, s->tick); -} - static void systick_timer_tick(void *opaque) { SysTickState *s = (SysTickState *)opaque; @@ -70,10 +50,12 @@ static void systick_timer_tick(void *opaque) /* Tell the NVIC to pend the SysTick exception */ qemu_irq_pulse(s->irq); } - if (s->reload == 0) { - s->control &= ~SYSTICK_ENABLE; - } else { - systick_reload(s, 0); + if (ptimer_get_limit(s->ptimer) == 0) { + /* + * Timer expiry with SYST_RVR zero disables the timer + * (but doesn't clear SYST_CSR.ENABLE) + */ + ptimer_stop(s->ptimer); } } @@ -94,30 +76,11 @@ static MemTxResult systick_read(void *opaque, hwaddr addr, uint64_t *data, s->control &= ~SYSTICK_COUNTFLAG; break; case 0x4: /* SysTick Reload Value. */ - val = s->reload; + val = ptimer_get_limit(s->ptimer); break; case 0x8: /* SysTick Current Value. */ - { - int64_t t; - - if ((s->control & SYSTICK_ENABLE) == 0) { - val = 0; - break; - } - t = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); - if (t >= s->tick) { - val = 0; - break; - } - val = ((s->tick - (t + 1)) / systick_scale(s)) + 1; - /* The interrupt in triggered when the timer reaches zero. - However the counter is not reloaded until the next clock - tick. This is a hack to return zero during the first tick. */ - if (val > s->reload) { - val = 0; - } + val = ptimer_get_count(s->ptimer); break; - } case 0xc: /* SysTick Calibration Value. */ val = 10000; break; @@ -149,39 +112,50 @@ static MemTxResult systick_write(void *opaque, hwaddr addr, switch (addr) { case 0x0: /* SysTick Control and Status. */ { - uint32_t oldval = s->control; + uint32_t oldval; + ptimer_transaction_begin(s->ptimer); + oldval = s->control; s->control &= 0xfffffff8; s->control |= value & 7; + if ((oldval ^ value) & SYSTICK_ENABLE) { - int64_t now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); if (value & SYSTICK_ENABLE) { - if (s->tick) { - s->tick += now; - timer_mod(s->timer, s->tick); - } else { - systick_reload(s, 1); - } + /* + * Always reload the period in case board code has + * changed system_clock_scale. If we ever replace that + * global with a more sensible API then we might be able + * to set the period only when it actually changes. + */ + ptimer_set_period(s->ptimer, systick_scale(s)); + ptimer_run(s->ptimer, 0); } else { - timer_del(s->timer); - s->tick -= now; - if (s->tick < 0) { - s->tick = 0; - } + ptimer_stop(s->ptimer); } } else if ((oldval ^ value) & SYSTICK_CLKSOURCE) { - /* This is a hack. Force the timer to be reloaded - when the reference clock is changed. */ - systick_reload(s, 1); + ptimer_set_period(s->ptimer, systick_scale(s)); } + ptimer_transaction_commit(s->ptimer); break; } case 0x4: /* SysTick Reload Value. */ - s->reload = value; + ptimer_transaction_begin(s->ptimer); + ptimer_set_limit(s->ptimer, value & 0xffffff, 0); + ptimer_transaction_commit(s->ptimer); break; - case 0x8: /* SysTick Current Value. Writes reload the timer. */ - systick_reload(s, 1); + case 0x8: /* SysTick Current Value. */ + /* + * Writing any value clears SYST_CVR to zero and clears + * SYST_CSR.COUNTFLAG. The counter will then reload from SYST_RVR + * on the next clock edge unless SYST_RVR is zero. + */ + ptimer_transaction_begin(s->ptimer); + if (ptimer_get_limit(s->ptimer) == 0) { + ptimer_stop(s->ptimer); + } + ptimer_set_count(s->ptimer, 0); s->control &= ~SYSTICK_COUNTFLAG; + ptimer_transaction_commit(s->ptimer); break; default: qemu_log_mask(LOG_GUEST_ERROR, @@ -210,10 +184,13 @@ static void systick_reset(DeviceState *dev) */ assert(system_clock_scale != 0); + ptimer_transaction_begin(s->ptimer); s->control = 0; - s->reload = 0; - s->tick = 0; - timer_del(s->timer); + ptimer_stop(s->ptimer); + ptimer_set_count(s->ptimer, 0); + ptimer_set_limit(s->ptimer, 0, 0); + ptimer_set_period(s->ptimer, systick_scale(s)); + ptimer_transaction_commit(s->ptimer); } static void systick_instance_init(Object *obj) @@ -229,18 +206,21 @@ static void systick_instance_init(Object *obj) static void systick_realize(DeviceState *dev, Error **errp) { SysTickState *s = SYSTICK(dev); - s->timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, systick_timer_tick, s); + s->ptimer = ptimer_init(systick_timer_tick, s, + PTIMER_POLICY_WRAP_AFTER_ONE_PERIOD | + PTIMER_POLICY_NO_COUNTER_ROUND_DOWN | + PTIMER_POLICY_NO_IMMEDIATE_RELOAD | + PTIMER_POLICY_TRIGGER_ONLY_ON_DECREMENT); } static const VMStateDescription vmstate_systick = { .name = "armv7m_systick", - .version_id = 1, - .minimum_version_id = 1, + .version_id = 2, + .minimum_version_id = 2, .fields = (VMStateField[]) { VMSTATE_UINT32(control, SysTickState), - VMSTATE_UINT32(reload, SysTickState), VMSTATE_INT64(tick, SysTickState), - VMSTATE_TIMER_PTR(timer, SysTickState), + VMSTATE_PTIMER(ptimer, SysTickState), VMSTATE_END_OF_LIST() } }; |