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| author | Randall Spangler <rspangler@chromium.org> | 2013-09-10 10:25:18 -0700 |
|---|---|---|
| committer | chrome-internal-fetch <chrome-internal-fetch@google.com> | 2013-09-11 22:41:22 +0000 |
| commit | af12f2f58c001dfa999591c29b055b7ba95379ba (patch) | |
| tree | 48867e99e48a62ae818b177cd45b1519d6ceaf5b /include/uart.h | |
| parent | 6b1dace9f456d5b1b160402866045c3659e665e0 (diff) | |
| download | chrome-ec-af12f2f58c001dfa999591c29b055b7ba95379ba.tar.gz | |
stm32: Support DMA-based UART output
This reduces the number of UART interrupts by a factor of 12, and
reduces the overall interrupt rate on STM32 by a factor of 2.
BUG=chrome-os-partner:20485
BRANCH=none (not required for pit branch)
TEST=Boot pit. Ctrl+Q pauses debug output; Ctrl+S resumes it.
'crash divzero' still prints a full crash dump.
And util/makeall.sh passes builds all platforms and passes tests.
Change-Id: I86993e14b436150298dcb2c6d29086cc3c9db418
Signed-off-by: Randall Spangler <rspangler@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/168814
Diffstat (limited to 'include/uart.h')
| -rw-r--r-- | include/uart.h | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/include/uart.h b/include/uart.h index fa50645270..fec3fd47ec 100644 --- a/include/uart.h +++ b/include/uart.h @@ -127,6 +127,19 @@ void uart_tx_flush(void); int uart_tx_ready(void); /** + * Return non-zero if UART is ready to start a DMA transfer. + */ +int uart_tx_dma_ready(void); + +/** + * Start a UART transmit DMA transfer + * + * @param src Pointer to data to send + * @param len Length of transfer in bytes + */ +void uart_tx_dma_start(const char *src, int len); + +/** * Return non-zero if the UART has a character available to read. */ int uart_rx_available(void); |