diff options
Diffstat (limited to 'hw/timer/imx_epit.c')
| -rw-r--r-- | hw/timer/imx_epit.c | 370 |
1 files changed, 220 insertions, 150 deletions
diff --git a/hw/timer/imx_epit.c b/hw/timer/imx_epit.c index ec0fa440d7..3a869782bc 100644 --- a/hw/timer/imx_epit.c +++ b/hw/timer/imx_epit.c @@ -6,6 +6,7 @@ * Originally written by Hans Jiang * Updated by Peter Chubb * Updated by Jean-Christophe Dubois <jcd@tribudubois.net> + * Updated by Axel Heider * * This code is licensed under GPL version 2 or later. See * the COPYING file in the top-level directory. @@ -66,73 +67,54 @@ static const IMXClk imx_epit_clocks[] = { */ static void imx_epit_update_int(IMXEPITState *s) { - if (s->sr && (s->cr & CR_OCIEN) && (s->cr & CR_EN)) { + if ((s->sr & SR_OCIF) && (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) +static uint32_t imx_epit_get_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); - } + uint32_t clksrc = extract32(s->cr, CR_CLKSRC_SHIFT, CR_CLKSRC_BITS); + uint32_t prescaler = 1 + extract32(s->cr, CR_PRESCALE_SHIFT, CR_PRESCALE_BITS); + uint32_t f_in = imx_ccm_get_clock_frequency(s->ccm, imx_epit_clocks[clksrc]); + uint32_t freq = f_in / prescaler; + DPRINTF("ptimer frequency is %u\n", freq); + return freq; } -static void imx_epit_reset(DeviceState *dev) +/* + * This is called both on hardware (device) reset and software reset. + */ +static void imx_epit_reset(IMXEPITState *s, bool is_hard_reset) { - 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); + /* Soft reset doesn't touch some bits; hard reset clears them */ + if (is_hard_reset) { + s->cr = 0; + } else { + 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 */ + + /* + * The reset switches off the input clock, so even if the CR.EN is still + * set, the timers are no longer running. + */ + assert(imx_epit_get_freq(s) == 0); 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); @@ -156,8 +138,7 @@ static uint64_t imx_epit_read(void *opaque, hwaddr offset, unsigned size) break; case 4: /* CNT */ - imx_epit_update_count(s); - reg_value = s->cnt; + reg_value = ptimer_get_count(s->timer_reload); break; default: @@ -171,144 +152,219 @@ static uint64_t imx_epit_read(void *opaque, hwaddr offset, unsigned size) 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) +/* + * Must be called from a ptimer_transaction_begin/commit block for + * s->timer_cmp, but outside of a transaction block of s->timer_reload, + * so the proper counter value is read. + */ +static void imx_epit_update_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); + uint64_t counter = 0; + bool is_oneshot = false; + /* + * The compare timer only has to run if the timer peripheral is active + * and there is an input clock, Otherwise it can be switched off. + */ + bool is_active = (s->cr & CR_EN) && imx_epit_get_freq(s); + if (is_active) { + /* + * Calculate next timeout for compare timer. Reading the reload + * counter returns proper results only if pending transactions + * on it are committed here. Otherwise stale values are be read. + */ + counter = ptimer_get_count(s->timer_reload); + uint64_t limit = ptimer_get_limit(s->timer_cmp); + /* + * The compare timer is a periodic timer if the limit is at least + * the compare value. Otherwise it may fire at most once in the + * current round. + */ + bool is_oneshot = (limit >= s->cmp); + if (counter >= s->cmp) { + /* The compare timer fires in the current round. */ + counter -= s->cmp; + } else if (!is_oneshot) { + /* + * The compare timer fires after a reload, as it is below the + * compare value already in this round. Note that the counter + * value calculated below can be above the 32-bit limit, which + * is legal here because the compare timer is an internal + * helper ptimer only. + */ + counter += limit - s->cmp; + } else { + /* + * The compare timer won't fire in this round, and the limit is + * set to a value below the compare value. This practically means + * it will never fire, so it can be switched off. + */ + is_active = false; } - ptimer_set_count(s->timer_cmp, next); } + + /* + * Set the compare timer and let it run, or stop it. This is agnostic + * of CR.OCIEN bit, as this bit affects interrupt generation only. The + * compare timer needs to run even if no interrupts are to be generated, + * because the SR.OCIF bit must be updated also. + * Note that the timer might already be stopped or be running with + * counter values. However, finding out when an update is needed and + * when not is not trivial. It's much easier applying the setting again, + * as this does not harm either and the overhead is negligible. + */ + if (is_active) { + ptimer_set_count(s->timer_cmp, counter); + ptimer_run(s->timer_cmp, is_oneshot ? 1 : 0); + } else { + ptimer_stop(s->timer_cmp); + } + } -static void imx_epit_write(void *opaque, hwaddr offset, uint64_t value, - unsigned size) +static void imx_epit_write_cr(IMXEPITState *s, uint32_t value) { - IMXEPITState *s = IMX_EPIT(opaque); - uint64_t oldcr; + uint32_t oldcr = s->cr; - DPRINTF("(%s, value = 0x%08x)\n", imx_epit_reg_name(offset >> 2), - (uint32_t)value); - - switch (offset >> 2) { - case 0: /* CR */ + s->cr = value & 0x03ffffff; - 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. - */ - } + if (s->cr & CR_SWR) { + /* + * Reset clears CR.SWR again. It does not touch CR.EN, but the timers + * are still stopped because the input clock is disabled. + */ + imx_epit_reset(s, false); + } else { + uint32_t freq; + uint32_t toggled_cr_bits = oldcr ^ s->cr; + /* re-initialize the limits if CR.RLD has changed */ + bool set_limit = toggled_cr_bits & CR_RLD; + /* set the counter if the timer got just enabled and CR.ENMOD is set */ + bool is_switched_on = (toggled_cr_bits & s->cr) & CR_EN; + bool set_counter = is_switched_on && (s->cr & CR_ENMOD); ptimer_transaction_begin(s->timer_cmp); ptimer_transaction_begin(s->timer_reload); - - if (!(s->cr & CR_SWR)) { - imx_epit_set_freq(s); + freq = imx_epit_get_freq(s); + if (freq) { + ptimer_set_freq(s->timer_reload, freq); + ptimer_set_freq(s->timer_cmp, freq); } - 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); - } + if (set_limit || set_counter) { + uint64_t limit = (s->cr & CR_RLD) ? s->lr : EPIT_TIMER_MAX; + ptimer_set_limit(s->timer_reload, limit, set_counter ? 1 : 0); + if (set_limit) { + ptimer_set_limit(s->timer_cmp, limit, 0); } - - imx_epit_reload_compare_timer(s); + } + /* + * If there is an input clock and the peripheral is enabled, then + * ensure the wall clock timer is ticking. Otherwise stop the timers. + * The compare timer will be updated later. + */ + if (freq && (s->cr & CR_EN)) { 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_stop(s->timer_reload); } - - ptimer_transaction_commit(s->timer_cmp); + /* Commit changes to reload timer, so they can propagate. */ ptimer_transaction_commit(s->timer_reload); - break; + /* Update compare timer based on the committed reload timer value. */ + imx_epit_update_compare_timer(s); + ptimer_transaction_commit(s->timer_cmp); + } - case 1: /* SR - ACK*/ - /* writing 1 to OCIF clear the OCIF bit */ - if (value & 0x01) { - s->sr = 0; - imx_epit_update_int(s); - } - break; + /* + * The interrupt state can change due to: + * - reset clears both SR.OCIF and CR.OCIE + * - write to CR.EN or CR.OCIE + */ + imx_epit_update_int(s); +} - case 2: /* LR - set ticks */ - s->lr = value; +static void imx_epit_write_sr(IMXEPITState *s, uint32_t value) +{ + /* writing 1 to SR.OCIF clears this bit and turns the interrupt off */ + if (value & SR_OCIF) { + s->sr = 0; /* SR.OCIF is the only bit in this register anyway */ + imx_epit_update_int(s); + } +} - 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); +static void imx_epit_write_lr(IMXEPITState *s, uint32_t value) +{ + 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 changes to s->timer_reload, so they can propagate. */ + ptimer_transaction_commit(s->timer_reload); + /* Update the compare timer based on the committed reload timer value. */ + imx_epit_update_compare_timer(s); + ptimer_transaction_commit(s->timer_cmp); +} + +static void imx_epit_write_cmp(IMXEPITState *s, uint32_t value) +{ + s->cmp = value; + + /* Update the compare timer based on the committed reload timer value. */ + ptimer_transaction_begin(s->timer_cmp); + imx_epit_update_compare_timer(s); + ptimer_transaction_commit(s->timer_cmp); +} + +static void imx_epit_write(void *opaque, hwaddr offset, uint64_t value, + unsigned size) +{ + IMXEPITState *s = IMX_EPIT(opaque); + + DPRINTF("(%s, value = 0x%08x)\n", imx_epit_reg_name(offset >> 2), + (uint32_t)value); + + switch (offset >> 2) { + case 0: /* CR */ + imx_epit_write_cr(s, (uint32_t)value); break; - case 3: /* CMP */ - s->cmp = value; + case 1: /* SR */ + imx_epit_write_sr(s, (uint32_t)value); + break; - ptimer_transaction_begin(s->timer_cmp); - imx_epit_reload_compare_timer(s); - ptimer_transaction_commit(s->timer_cmp); + case 2: /* LR */ + imx_epit_write_lr(s, (uint32_t)value); + break; + case 3: /* CMP */ + imx_epit_write_cmp(s, (uint32_t)value); 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); + /* The cmp ptimer can't be running when the peripheral is disabled */ + assert(s->cr & CR_EN); - s->sr = 1; + DPRINTF("sr was %d\n", s->sr); + /* Set interrupt status bit SR.OCIF and update the interrupt state */ + s->sr |= SR_OCIF; imx_epit_update_int(s); } @@ -325,15 +381,13 @@ static const MemoryRegionOps imx_epit_ops = { static const VMStateDescription vmstate_imx_timer_epit = { .name = TYPE_IMX_EPIT, - .version_id = 2, - .minimum_version_id = 2, + .version_id = 3, + .minimum_version_id = 3, .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() @@ -352,17 +406,33 @@ static void imx_epit_realize(DeviceState *dev, Error **errp) 0x00001000); sysbus_init_mmio(sbd, &s->iomem); + /* + * The reload timer keeps running when the peripheral is enabled. It is a + * kind of wall clock that does not generate any interrupts. The callback + * needs to be provided, but it does nothing as the ptimer already supports + * all necessary reloading functionality. + */ s->timer_reload = ptimer_init(imx_epit_reload, s, PTIMER_POLICY_LEGACY); + /* + * The compare timer is running only when the peripheral configuration is + * in a state that will generate compare interrupts. + */ s->timer_cmp = ptimer_init(imx_epit_cmp, s, PTIMER_POLICY_LEGACY); } +static void imx_epit_dev_reset(DeviceState *dev) +{ + IMXEPITState *s = IMX_EPIT(dev); + imx_epit_reset(s, true); +} + 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->reset = imx_epit_dev_reset; dc->vmsd = &vmstate_imx_timer_epit; dc->desc = "i.MX periodic timer"; } |