On 7/9/20 2:36 AM, Havard Skinnemoen wrote: > The NPCM730 and NPCM750 SoCs have three timer modules each holding five > timers and some shared registers (e.g. interrupt status). > > Each timer runs at 25 MHz divided by a prescaler, and counts down from a > configurable initial value to zero. When zero is reached, the interrupt > flag for the timer is set, and the timer is disabled (one-shot mode) or > reloaded from its initial value (periodic mode). > > This implementation is sufficient to boot a Linux kernel configured for > NPCM750. Note that the kernel does not seem to actually turn on the > interrupts. > > Reviewed-by: Tyrone Ting <kft...@nuvoton.com> > Reviewed-by: Joel Stanley <j...@jms.id.au> > Signed-off-by: Havard Skinnemoen <hskinnem...@google.com> > --- > include/hw/timer/npcm7xx_timer.h | 96 +++++++ > hw/timer/npcm7xx_timer.c | 468 +++++++++++++++++++++++++++++++ > hw/timer/Makefile.objs | 1 + > hw/timer/trace-events | 5 + > 4 files changed, 570 insertions(+) > create mode 100644 include/hw/timer/npcm7xx_timer.h > create mode 100644 hw/timer/npcm7xx_timer.c > ...
> +/* The reference clock frequency is always 25 MHz. */ > +#define NPCM7XX_TIMER_REF_HZ (25000000) > + > +/* Return the value by which to divide the reference clock rate. */ > +static uint32_t npcm7xx_timer_prescaler(const NPCM7xxTimer *t) > +{ > + return extract32(t->tcsr, NPCM7XX_TCSR_PRESCALE_START, > + NPCM7XX_TCSR_PRESCALE_LEN) + 1; > +} > + > +/* Convert a timer cycle count to a time interval in nanoseconds. */ > +static int64_t npcm7xx_timer_count_to_ns(NPCM7xxTimer *t, uint32_t count) > +{ > + int64_t ns = count; > + > + ns *= NANOSECONDS_PER_SECOND / NPCM7XX_TIMER_REF_HZ; > + ns *= npcm7xx_timer_prescaler(t); > + > + return ns; > +} > + > +/* Convert a time interval in nanoseconds to a timer cycle count. */ > +static uint32_t npcm7xx_timer_ns_to_count(NPCM7xxTimer *t, int64_t ns) > +{ > + int64_t count; > + > + count = ns / (NANOSECONDS_PER_SECOND / NPCM7XX_TIMER_REF_HZ); > + count /= npcm7xx_timer_prescaler(t); > + > + return count; > +} > + > +/* > + * Raise the interrupt line if there's a pending interrupt and interrupts are > + * enabled for this timer. If not, lower it. > + */ > +static void npcm7xx_timer_check_interrupt(NPCM7xxTimer *t) > +{ > + NPCM7xxTimerCtrlState *tc = t->ctrl; > + /* Find the array index of this timer. */ > + int index = t - tc->timer; As you suggested in another device in this series, using a getter here is clearer. > + > + g_assert(index >= 0 && index < NPCM7XX_TIMERS_PER_CTRL); > + > + if ((t->tcsr & NPCM7XX_TCSR_IE) && (tc->tisr & BIT(index))) { > + qemu_irq_raise(t->irq); > + trace_npcm7xx_timer_irq(DEVICE(tc)->canonical_path, index, 1); > + } else { > + qemu_irq_lower(t->irq); > + trace_npcm7xx_timer_irq(DEVICE(tc)->canonical_path, index, 0); > + } > +} > + > +/* Start or resume the timer. */ > +static void npcm7xx_timer_start(NPCM7xxTimer *t) > +{ > + int64_t now; > + > + now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); > + t->expires_ns = now + t->remaining_ns; > + timer_mod(&t->qtimer, t->expires_ns); > +} > + > +/* > + * Called when the counter reaches zero. Sets the interrupt flag, and either > + * restarts or disables the timer. > + */ > +static void npcm7xx_timer_reached_zero(NPCM7xxTimer *t) > +{ > + NPCM7xxTimerCtrlState *tc = t->ctrl; > + int index = t - tc->timer; > + > + g_assert(index >= 0 && index < NPCM7XX_TIMERS_PER_CTRL); > + > + tc->tisr |= BIT(index); > + > + if (t->tcsr & NPCM7XX_TCSR_PERIODIC) { > + t->remaining_ns = npcm7xx_timer_count_to_ns(t, t->ticr); > + if (t->tcsr & NPCM7XX_TCSR_CEN) { > + npcm7xx_timer_start(t); > + } > + } else { > + t->tcsr &= ~(NPCM7XX_TCSR_CEN | NPCM7XX_TCSR_CACT); > + } > + > + npcm7xx_timer_check_interrupt(t); > +} > + > +/* Stop counting. Record the time remaining so we can continue later. */ > +static void npcm7xx_timer_pause(NPCM7xxTimer *t) > +{ > + int64_t now; > + > + timer_del(&t->qtimer); > + now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); > + t->remaining_ns = t->expires_ns - now; > + if (t->remaining_ns <= 0) { Can this happen? Shouldn't we get npcm7xx_timer_expired() before? > + npcm7xx_timer_reached_zero(t); > + } > +} > + > +/* > + * Restart the timer from its initial value. If the timer was enabled and > stays > + * enabled, adjust the QEMU timer according to the new count. If the timer is > + * transitioning from disabled to enabled, the caller is expected to start > the > + * timer later. > + */ > +static void npcm7xx_timer_restart(NPCM7xxTimer *t, uint32_t old_tcsr) > +{ > + t->remaining_ns = npcm7xx_timer_count_to_ns(t, t->ticr); > + > + if (old_tcsr & t->tcsr & NPCM7XX_TCSR_CEN) { > + npcm7xx_timer_start(t); > + } > +} > + > +/* Register read and write handlers */ > + > +static void npcm7xx_timer_write_tcsr(NPCM7xxTimer *t, uint32_t new_tcsr) > +{ > + uint32_t old_tcsr = t->tcsr; > + > + if (new_tcsr & NPCM7XX_TCSR_RSVD) { > + qemu_log_mask(LOG_GUEST_ERROR, "%s: reserved bits in 0x%08x > ignored\n", > + __func__, new_tcsr); > + new_tcsr &= ~NPCM7XX_TCSR_RSVD; > + } > + if (new_tcsr & NPCM7XX_TCSR_CACT) { > + qemu_log_mask(LOG_GUEST_ERROR, "%s: read-only bits in 0x%08x > ignored\n", > + __func__, new_tcsr); > + new_tcsr &= ~NPCM7XX_TCSR_CACT; > + } > + > + t->tcsr = (t->tcsr & NPCM7XX_TCSR_CACT) | new_tcsr; > + > + if ((old_tcsr ^ new_tcsr) & NPCM7XX_TCSR_IE) { > + npcm7xx_timer_check_interrupt(t); > + } > + if (new_tcsr & NPCM7XX_TCSR_CRST) { > + npcm7xx_timer_restart(t, old_tcsr); > + t->tcsr &= ~NPCM7XX_TCSR_CRST; > + } > + if ((old_tcsr ^ new_tcsr) & NPCM7XX_TCSR_CEN) { > + if (new_tcsr & NPCM7XX_TCSR_CEN) { > + npcm7xx_timer_start(t); > + } else { > + npcm7xx_timer_pause(t); > + } > + } > +} > + > +static void npcm7xx_timer_write_ticr(NPCM7xxTimer *t, uint32_t new_ticr) > +{ > + t->ticr = new_ticr; > + > + npcm7xx_timer_restart(t, t->tcsr); > +} > + > +static uint32_t npcm7xx_timer_read_tdr(NPCM7xxTimer *t) > +{ > + if (t->tcsr & NPCM7XX_TCSR_CEN) { > + int64_t now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); > + > + return npcm7xx_timer_ns_to_count(t, t->expires_ns - now); > + } > + > + return npcm7xx_timer_ns_to_count(t, t->remaining_ns); > +} > + > +static uint64_t npcm7xx_timer_read(void *opaque, hwaddr offset, unsigned > size) > +{ > + NPCM7xxTimerCtrlState *s = opaque; > + uint64_t value = 0; > + hwaddr reg; > + > + reg = offset / sizeof(uint32_t); > + switch (reg) { > + case NPCM7XX_TIMER_TCSR0: > + value = s->timer[0].tcsr; > + break; > + case NPCM7XX_TIMER_TCSR1: > + value = s->timer[1].tcsr; Maybe add: static hwaddr timer_index(hwaddr reg) { return reg - NPCM7XX_TIMER_TCSR0; } And use shorter: case NPCM7XX_TIMER_TCSR0: case NPCM7XX_TIMER_TCSR1: case NPCM7XX_TIMER_TCSR2: case NPCM7XX_TIMER_TCSR3: case NPCM7XX_TIMER_TCSR4: value = s->timer[timer_index(reg)].tcsr; break; Similarly with NPCM7XX_TIMER_TDRx and in npcm7xx_timer_write(). > + break; > + case NPCM7XX_TIMER_TCSR2: > + value = s->timer[2].tcsr; > + break; > + case NPCM7XX_TIMER_TCSR3: > + value = s->timer[3].tcsr; > + break; > + case NPCM7XX_TIMER_TCSR4: > + value = s->timer[4].tcsr; > + break; > + > + case NPCM7XX_TIMER_TICR0: > + value = s->timer[0].ticr; > + break; > + case NPCM7XX_TIMER_TICR1: > + value = s->timer[1].ticr; > + break; > + case NPCM7XX_TIMER_TICR2: > + value = s->timer[2].ticr; > + break; > + case NPCM7XX_TIMER_TICR3: > + value = s->timer[3].ticr; > + break; > + case NPCM7XX_TIMER_TICR4: > + value = s->timer[4].ticr; > + break; > + > + case NPCM7XX_TIMER_TDR0: > + value = npcm7xx_timer_read_tdr(&s->timer[0]); > + break; > + case NPCM7XX_TIMER_TDR1: > + value = npcm7xx_timer_read_tdr(&s->timer[1]); > + break; > + case NPCM7XX_TIMER_TDR2: > + value = npcm7xx_timer_read_tdr(&s->timer[2]); > + break; > + case NPCM7XX_TIMER_TDR3: > + value = npcm7xx_timer_read_tdr(&s->timer[3]); > + break; > + case NPCM7XX_TIMER_TDR4: > + value = npcm7xx_timer_read_tdr(&s->timer[4]); > + break; > + > + case NPCM7XX_TIMER_TISR: > + value = s->tisr; > + break; > + > + case NPCM7XX_TIMER_WTCR: > + value = s->wtcr; > + break; > + > + default: > + qemu_log_mask(LOG_GUEST_ERROR, "%s: invalid offset 0x%04x\n", > + __func__, (unsigned int)offset); > + break; > + } > + > + trace_npcm7xx_timer_read(DEVICE(s)->canonical_path, offset, value); > + > + return value; > +} > + > +static void npcm7xx_timer_write(void *opaque, hwaddr offset, > + uint64_t v, unsigned size) > +{ > + uint32_t reg = offset / sizeof(uint32_t); > + NPCM7xxTimerCtrlState *s = opaque; > + uint32_t value = v; > + > + trace_npcm7xx_timer_write(DEVICE(s)->canonical_path, offset, value); > + > + switch (reg) { > + case NPCM7XX_TIMER_TCSR0: > + npcm7xx_timer_write_tcsr(&s->timer[0], value); > + return; > + case NPCM7XX_TIMER_TCSR1: > + npcm7xx_timer_write_tcsr(&s->timer[1], value); > + return; > + case NPCM7XX_TIMER_TCSR2: > + npcm7xx_timer_write_tcsr(&s->timer[2], value); > + return; > + case NPCM7XX_TIMER_TCSR3: > + npcm7xx_timer_write_tcsr(&s->timer[3], value); > + return; > + case NPCM7XX_TIMER_TCSR4: > + npcm7xx_timer_write_tcsr(&s->timer[4], value); > + return; > + > + case NPCM7XX_TIMER_TICR0: > + npcm7xx_timer_write_ticr(&s->timer[0], value); > + return; > + case NPCM7XX_TIMER_TICR1: > + npcm7xx_timer_write_ticr(&s->timer[1], value); > + return; > + case NPCM7XX_TIMER_TICR2: > + npcm7xx_timer_write_ticr(&s->timer[2], value); > + return; > + case NPCM7XX_TIMER_TICR3: > + npcm7xx_timer_write_ticr(&s->timer[3], value); > + return; > + case NPCM7XX_TIMER_TICR4: > + npcm7xx_timer_write_ticr(&s->timer[4], value); > + return; > + > + case NPCM7XX_TIMER_TDR0: > + case NPCM7XX_TIMER_TDR1: > + case NPCM7XX_TIMER_TDR2: > + case NPCM7XX_TIMER_TDR3: > + case NPCM7XX_TIMER_TDR4: > + qemu_log_mask(LOG_GUEST_ERROR, "%s: register @ 0x%04x is > read-only\n", > + __func__, (unsigned int)offset); > + return; > + > + case NPCM7XX_TIMER_TISR: > + s->tisr &= ~value; > + return; > + > + case NPCM7XX_TIMER_WTCR: > + qemu_log_mask(LOG_UNIMP, "%s: WTCR write not implemented: 0x%08x\n", > + __func__, value); > + return; > + } > + > + qemu_log_mask(LOG_GUEST_ERROR, "%s: invalid offset 0x%04x\n", > + __func__, (unsigned int)offset); > +} > + > +static const struct MemoryRegionOps npcm7xx_timer_ops = { > + .read = npcm7xx_timer_read, > + .write = npcm7xx_timer_write, > + .endianness = DEVICE_LITTLE_ENDIAN, > + .valid = { > + .min_access_size = 4, > + .max_access_size = 4, > + .unaligned = false, > + }, > +}; > + > +/* Called when the QEMU timer expires. */ > +static void npcm7xx_timer_expired(void *opaque) > +{ > + NPCM7xxTimer *t = opaque; > + > + if (t->tcsr & NPCM7XX_TCSR_CEN) { > + npcm7xx_timer_reached_zero(t); > + } > +} ...