diff options
| -rw-r--r-- | hw/core/ptimer.c | 152 | ||||
| -rw-r--r-- | include/hw/ptimer.h | 72 |
2 files changed, 209 insertions, 15 deletions
diff --git a/hw/core/ptimer.c b/hw/core/ptimer.c index f0d3ce1139..7239b8227c 100644 --- a/hw/core/ptimer.c +++ b/hw/core/ptimer.c @@ -31,6 +31,16 @@ struct ptimer_state uint8_t policy_mask; QEMUBH *bh; QEMUTimer *timer; + ptimer_cb callback; + void *callback_opaque; + /* + * These track whether we're in a transaction block, and if we + * need to do a timer reload when the block finishes. They don't + * need to be migrated because migration can never happen in the + * middle of a transaction block. + */ + bool in_transaction; + bool need_reload; }; /* Use a bottom-half routine to avoid reentrancy issues. */ @@ -39,13 +49,16 @@ static void ptimer_trigger(ptimer_state *s) if (s->bh) { replay_bh_schedule_event(s->bh); } + if (s->callback) { + s->callback(s->callback_opaque); + } } static void ptimer_reload(ptimer_state *s, int delta_adjust) { - uint32_t period_frac = s->period_frac; - uint64_t period = s->period; - uint64_t delta = s->delta; + uint32_t period_frac; + uint64_t period; + uint64_t delta; bool suppress_trigger = false; /* @@ -58,11 +71,20 @@ static void ptimer_reload(ptimer_state *s, int delta_adjust) (s->policy_mask & PTIMER_POLICY_TRIGGER_ONLY_ON_DECREMENT)) { suppress_trigger = true; } - if (delta == 0 && !(s->policy_mask & PTIMER_POLICY_NO_IMMEDIATE_TRIGGER) + if (s->delta == 0 && !(s->policy_mask & PTIMER_POLICY_NO_IMMEDIATE_TRIGGER) && !suppress_trigger) { ptimer_trigger(s); } + /* + * Note that ptimer_trigger() might call the device callback function, + * which can then modify timer state, so we must not cache any fields + * from ptimer_state until after we have called it. + */ + delta = s->delta; + period = s->period; + period_frac = s->period_frac; + if (delta == 0 && !(s->policy_mask & PTIMER_POLICY_NO_IMMEDIATE_RELOAD)) { delta = s->delta = s->limit; } @@ -136,6 +158,15 @@ static void ptimer_tick(void *opaque) ptimer_state *s = (ptimer_state *)opaque; bool trigger = true; + /* + * We perform all the tick actions within a begin/commit block + * because the callback function that ptimer_trigger() calls + * might make calls into the ptimer APIs that provoke another + * trigger, and we want that to cause the callback function + * to be called iteratively, not recursively. + */ + ptimer_transaction_begin(s); + if (s->enabled == 2) { s->delta = 0; s->enabled = 0; @@ -164,6 +195,8 @@ static void ptimer_tick(void *opaque) if (trigger) { ptimer_trigger(s); } + + ptimer_transaction_commit(s); } uint64_t ptimer_get_count(ptimer_state *s) @@ -263,10 +296,15 @@ uint64_t ptimer_get_count(ptimer_state *s) void ptimer_set_count(ptimer_state *s, uint64_t count) { + assert(s->in_transaction || !s->callback); s->delta = count; if (s->enabled) { - s->next_event = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); - ptimer_reload(s, 0); + if (!s->callback) { + s->next_event = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); + ptimer_reload(s, 0); + } else { + s->need_reload = true; + } } } @@ -274,6 +312,8 @@ void ptimer_run(ptimer_state *s, int oneshot) { bool was_disabled = !s->enabled; + assert(s->in_transaction || !s->callback); + if (was_disabled && s->period == 0) { if (!qtest_enabled()) { fprintf(stderr, "Timer with period zero, disabling\n"); @@ -282,8 +322,12 @@ void ptimer_run(ptimer_state *s, int oneshot) } s->enabled = oneshot ? 2 : 1; if (was_disabled) { - s->next_event = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); - ptimer_reload(s, 0); + if (!s->callback) { + s->next_event = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); + ptimer_reload(s, 0); + } else { + s->need_reload = true; + } } } @@ -291,35 +335,50 @@ void ptimer_run(ptimer_state *s, int oneshot) is immediately restarted. */ void ptimer_stop(ptimer_state *s) { + assert(s->in_transaction || !s->callback); + if (!s->enabled) return; s->delta = ptimer_get_count(s); timer_del(s->timer); s->enabled = 0; + if (s->callback) { + s->need_reload = false; + } } /* Set counter increment interval in nanoseconds. */ void ptimer_set_period(ptimer_state *s, int64_t period) { + assert(s->in_transaction || !s->callback); s->delta = ptimer_get_count(s); s->period = period; s->period_frac = 0; if (s->enabled) { - s->next_event = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); - ptimer_reload(s, 0); + if (!s->callback) { + s->next_event = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); + ptimer_reload(s, 0); + } else { + s->need_reload = true; + } } } /* Set counter frequency in Hz. */ void ptimer_set_freq(ptimer_state *s, uint32_t freq) { + assert(s->in_transaction || !s->callback); s->delta = ptimer_get_count(s); s->period = 1000000000ll / freq; s->period_frac = (1000000000ll << 32) / freq; if (s->enabled) { - s->next_event = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); - ptimer_reload(s, 0); + if (!s->callback) { + s->next_event = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); + ptimer_reload(s, 0); + } else { + s->need_reload = true; + } } } @@ -327,12 +386,17 @@ void ptimer_set_freq(ptimer_state *s, uint32_t freq) count = limit. */ void ptimer_set_limit(ptimer_state *s, uint64_t limit, int reload) { + assert(s->in_transaction || !s->callback); s->limit = limit; if (reload) s->delta = limit; if (s->enabled && reload) { - s->next_event = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); - ptimer_reload(s, 0); + if (!s->callback) { + s->next_event = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); + ptimer_reload(s, 0); + } else { + s->need_reload = true; + } } } @@ -341,6 +405,32 @@ uint64_t ptimer_get_limit(ptimer_state *s) return s->limit; } +void ptimer_transaction_begin(ptimer_state *s) +{ + assert(!s->in_transaction || !s->callback); + s->in_transaction = true; + s->need_reload = false; +} + +void ptimer_transaction_commit(ptimer_state *s) +{ + assert(s->in_transaction); + /* + * We must loop here because ptimer_reload() can call the callback + * function, which might then update ptimer state in a way that + * means we need to do another reload and possibly another callback. + * A disabled timer never needs reloading (and if we don't check + * this then we loop forever if ptimer_reload() disables the timer). + */ + while (s->need_reload && s->enabled) { + s->need_reload = false; + s->next_event = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); + ptimer_reload(s, 0); + } + /* Now we've finished reload we can leave the transaction block. */ + s->in_transaction = false; +} + const VMStateDescription vmstate_ptimer = { .name = "ptimer", .version_id = 1, @@ -377,9 +467,41 @@ ptimer_state *ptimer_init_with_bh(QEMUBH *bh, uint8_t policy_mask) return s; } +ptimer_state *ptimer_init(ptimer_cb callback, void *callback_opaque, + uint8_t policy_mask) +{ + ptimer_state *s; + + /* + * The callback function is mandatory; so we use it to distinguish + * old-style QEMUBH ptimers from new transaction API ptimers. + * (ptimer_init_with_bh() allows a NULL bh pointer and at least + * one device (digic-timer) passes NULL, so it's not the case + * that either s->bh != NULL or s->callback != NULL.) + */ + assert(callback); + + s = g_new0(ptimer_state, 1); + s->timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, ptimer_tick, s); + s->policy_mask = policy_mask; + s->callback = callback; + s->callback_opaque = callback_opaque; + + /* + * These two policies are incompatible -- trigger-on-decrement implies + * a timer trigger when the count becomes 0, but no-immediate-trigger + * implies a trigger when the count stops being 0. + */ + assert(!((policy_mask & PTIMER_POLICY_TRIGGER_ONLY_ON_DECREMENT) && + (policy_mask & PTIMER_POLICY_NO_IMMEDIATE_TRIGGER))); + return s; +} + void ptimer_free(ptimer_state *s) { - qemu_bh_delete(s->bh); + if (s->bh) { + qemu_bh_delete(s->bh); + } timer_free(s->timer); g_free(s); } diff --git a/include/hw/ptimer.h b/include/hw/ptimer.h index 2fb9ba1915..4c321f65dc 100644 --- a/include/hw/ptimer.h +++ b/include/hw/ptimer.h @@ -92,6 +92,38 @@ typedef void (*ptimer_cb)(void *opaque); ptimer_state *ptimer_init_with_bh(QEMUBH *bh, uint8_t policy_mask); /** + * ptimer_init - Allocate and return a new ptimer + * @callback: function to call on ptimer expiry + * @callback_opaque: opaque pointer passed to @callback + * @policy: PTIMER_POLICY_* bits specifying behaviour + * + * The ptimer returned must be freed using ptimer_free(). + * + * If a ptimer is created using this API then will use the + * transaction-based API for modifying ptimer state: all calls + * to functions which modify ptimer state: + * - ptimer_set_period() + * - ptimer_set_freq() + * - ptimer_set_limit() + * - ptimer_set_count() + * - ptimer_run() + * - ptimer_stop() + * must be between matched calls to ptimer_transaction_begin() + * and ptimer_transaction_commit(). When ptimer_transaction_commit() + * is called it will evaluate the state of the timer after all the + * changes in the transaction, and call the callback if necessary. + * + * The callback function is always called from within a transaction + * begin/commit block, so the callback should not call the + * ptimer_transaction_begin() function itself. If the callback changes + * the ptimer state such that another ptimer expiry is triggered, then + * the callback will be called a second time after the first call returns. + */ +ptimer_state *ptimer_init(ptimer_cb callback, + void *callback_opaque, + uint8_t policy_mask); + +/** * ptimer_free - Free a ptimer * @s: timer to free * @@ -101,6 +133,28 @@ ptimer_state *ptimer_init_with_bh(QEMUBH *bh, uint8_t policy_mask); void ptimer_free(ptimer_state *s); /** + * ptimer_transaction_begin() - Start a ptimer modification transaction + * + * This function must be called before making any calls to functions + * which modify the ptimer's state (see the ptimer_init() documentation + * for a list of these), and must always have a matched call to + * ptimer_transaction_commit(). + * It is an error to call this function for a BH-based ptimer; + * attempting to do this will trigger an assert. + */ +void ptimer_transaction_begin(ptimer_state *s); + +/** + * ptimer_transaction_commit() - Commit a ptimer modification transaction + * + * This function must be called after calls to functions which modify + * the ptimer's state, and completes the update of the ptimer. If the + * ptimer state now means that we should trigger the timer expiry + * callback, it will be called directly. + */ +void ptimer_transaction_commit(ptimer_state *s); + +/** * ptimer_set_period - Set counter increment interval in nanoseconds * @s: ptimer to configure * @period: period of the counter in nanoseconds @@ -108,6 +162,9 @@ void ptimer_free(ptimer_state *s); * Note that if your counter behaviour is specified as having a * particular frequency rather than a period then ptimer_set_freq() * may be more appropriate. + * + * This function will assert if it is called outside a + * ptimer_transaction_begin/commit block, unless this is a bottom-half ptimer. */ void ptimer_set_period(ptimer_state *s, int64_t period); @@ -121,6 +178,9 @@ void ptimer_set_period(ptimer_state *s, int64_t period); * as setting the frequency then this function is more appropriate, * because it allows specifying an effective period which is * precise to fractions of a nanosecond, avoiding rounding errors. + * + * This function will assert if it is called outside a + * ptimer_transaction_begin/commit block, unless this is a bottom-half ptimer. */ void ptimer_set_freq(ptimer_state *s, uint32_t freq); @@ -148,6 +208,9 @@ uint64_t ptimer_get_limit(ptimer_state *s); * Set the limit value of the down-counter. The @reload flag can * be used to emulate the behaviour of timers which immediately * reload the counter when their reload register is written to. + * + * This function will assert if it is called outside a + * ptimer_transaction_begin/commit block, unless this is a bottom-half ptimer. */ void ptimer_set_limit(ptimer_state *s, uint64_t limit, int reload); @@ -169,6 +232,9 @@ uint64_t ptimer_get_count(ptimer_state *s); * Set the value of the down-counter. If the counter is currently * enabled this will arrange for a timer callback at the appropriate * point in the future. + * + * This function will assert if it is called outside a + * ptimer_transaction_begin/commit block, unless this is a bottom-half ptimer. */ void ptimer_set_count(ptimer_state *s, uint64_t count); @@ -183,6 +249,9 @@ void ptimer_set_count(ptimer_state *s, uint64_t count); * the counter value will then be reloaded from the limit and it will * start counting down again. If @oneshot is non-zero, then the counter * will disable itself when it reaches zero. + * + * This function will assert if it is called outside a + * ptimer_transaction_begin/commit block, unless this is a bottom-half ptimer. */ void ptimer_run(ptimer_state *s, int oneshot); @@ -195,6 +264,9 @@ void ptimer_run(ptimer_state *s, int oneshot); * * Note that this can cause it to "lose" time, even if it is immediately * restarted. + * + * This function will assert if it is called outside a + * ptimer_transaction_begin/commit block, unless this is a bottom-half ptimer. */ void ptimer_stop(ptimer_state *s); |