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lib: sbi_timer: Added a conditional wait function which can timeout

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Motivation: Suppose a peripheral needs to be configured to transmit
data. There is an SFR bit which indicates that the peripheral is ready
to transmit. The firmware should check the bit and will only transmit
data when the peripheral is ready. When the firmware starts polling the
SFR, the peripheral could be busy transmitting/receiving other data so
the firmware must wait till that completes. Assuming that there is no
other way, the firmware shouldn't wait indefinitely.

The function sbi_timer_waitms_until() will constantly check whether a
certain condition is satisfied, or timeout occurs. It can be used for
the cases when a timeout is required.

Signed-off-by: Adnan Rahman Chowdhury <adnan.chowdhury@sifive.com>
Reviewed-by: Xiang W <wxjstz@126.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
This commit is contained in:
Adnan Rahman Chowdhury
2022-06-30 10:46:35 +01:00
committed by Anup Patel
parent 4489876e93
commit 994c8cfb29
2 changed files with 31 additions and 0 deletions
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13
lib/sbi/sbi_timer.c
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@@ -76,6 +76,19 @@ void sbi_timer_delay_loop(ulong units, u64 unit_freq,
delay_fn(opaque);
}
bool sbi_timer_waitms_until(bool (*predicate)(void *), void *arg,
uint64_t timeout_ms)
{
uint64_t start_time = sbi_timer_value();
uint64_t ticks =
(sbi_timer_get_device()->timer_freq / 1000) *
timeout_ms;
while(!predicate(arg))
if (sbi_timer_value() - start_time >= ticks)
return false;
return true;
}
u64 sbi_timer_value(void)
{
if (get_time_val)