mirror of https://github.com/xemu-project/xemu.git
78b6eaa6f3
Provide the new transaction-based API. If a ptimer is created using ptimer_init() rather than ptimer_init_with_bh(), then instead of providing a QEMUBH, it provides a pointer to the callback function directly, and has opted into the transaction API. 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. In the old API the individual update functions generally would call ptimer_trigger() immediately, which would schedule the QEMUBH. In the new API the update functions will instead defer the "set s->next_event and call ptimer_reload()" work to ptimer_transaction_commit(). Because ptimer_trigger() can now immediately call into the device code which may then call other ptimer functions that update ptimer_state fields, we must be more careful in ptimer_reload() not to cache fields from ptimer_state across the ptimer_trigger() call. (This was harmless with the QEMUBH mechanism as the BH would not be invoked until much later.) We use assertions to check that: * the functions modifying ptimer state are not called outside a transaction block * ptimer_transaction_begin() and _commit() calls are paired * the transaction API is not used with a QEMUBH ptimer There is some slight repetition of code: * most of the set functions have similar looking "if s->bh call ptimer_reload, otherwise set s->need_reload" code * ptimer_init() and ptimer_init_with_bh() have similar code We deliberately don't try to avoid this repetition, because it will all be deleted when the QEMUBH version of the API is removed. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Message-id: 20191008171740.9679-3-peter.maydell@linaro.org |
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| cris | ||
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| timer | ||
| tpm | ||
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| watchdog | ||
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| Kconfig | ||
| Makefile.objs | ||