github/sparrow-kata-full
1
0
Fork 0
mirror of https://github.com/AmbiML/sparrow-kata-full.git synced 2025-09-18 08:06:22 +00:00
Code Issues Projects Releases Wiki Activity

processmanager: use rx_fifo_level in OpenTitanUARTDriver

Browse Source 
Use RX_FIFO_LEVEL additionally to RX_EMPTY. This improves
performance a bit, as RX_EMPTY register and circular buffer
status don't have to be read for every byte.

Change-Id: Ib56b4c6a0dc5689b63941b449f476f3555421abb
GitOrigin-RevId: f7a46154afaf5be28feab173687cebd8b584e8f4
This commit is contained in:
Marcin Witkowski
2022-01-27 13:10:04 +01:00
committed by Sam Leffler
parent 8961c75d25
commit 18474970dc
1 changed files with 12 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
apps/system/components/OpenTitanUARTDriver/src/driver.c
View File

@@ -76,6 +76,11 @@ static uint32_t tx_fifo_level() {
return SHIFT_DOWN_AND_MASK(REG(FIFO_STATUS), FIFO_STATUS, TXLVL);
}
// Gets the number of unread bytes in the RX FIFO from hardware MMIO.
static uint32_t rx_fifo_level() {
return SHIFT_DOWN_AND_MASK(REG(FIFO_STATUS), FIFO_STATUS, RXLVL);
}
// Gets whether the receive FIFO empty status bit is set.
//
// Prefer this to FIFO_STATUS.RXLVL, which the simulation has sometimes reported
@@ -276,7 +281,8 @@ void tx_watermark_handle(void) {
void rx_watermark_handle(void) {
LOCK(rx_mutex);
while (!rx_empty()) {
if (circular_buffer_remaining(&rx_buf) == 0) {
size_t buffer_remaining = circular_buffer_remaining(&rx_buf);
if (buffer_remaining == 0) {
// The buffer is full.
//
// We want to stay in this invocation of the interrupt handler until the
@@ -289,7 +295,11 @@ void rx_watermark_handle(void) {
LOCK(rx_mutex);
continue;
}
KATA_ASSERT(circular_buffer_push_back(&rx_buf, uart_getchar()));
size_t to_read = rx_fifo_level();
to_read = to_read > buffer_remaining ? buffer_remaining : to_read;
while(to_read--) {
KATA_ASSERT(circular_buffer_push_back(&rx_buf, uart_getchar()));
}
}
KATA_ASSERT(rx_nonempty_semaphore_post() == 0);
UNLOCK(rx_mutex);