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spi: Introduce one new field to set word delay 

For some SPI controllers, after each word size (specified by bits_per_word)
transimission, the hardware need some delay to make sure the slave has enough
time to receive the whole data.

So introducing one new 'word_delay' field of struct spi_tansfer for slave
devices to set this inter word delay time.

Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
hifive-unleashed-5.1
Baolin Wang 2018-08-16 20:54:49 +08:00 committed by Mark Brown
parent 864822235f
commit eeaceb8b7d
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1 changed files with 3 additions and 0 deletions
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include/linux/spi/spi.h
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@ -711,6 +711,8 @@ extern void spi_res_release(struct spi_controller *ctlr,
* @delay_usecs: microseconds to delay after this transfer before
* (optionally) changing the chipselect status, then starting
* the next transfer or completing this @spi_message.
* @word_delay: clock cycles to inter word delay after each word size
* (set by bits_per_word) transmission.
* @transfer_list: transfers are sequenced through @spi_message.transfers
* @tx_sg: Scatterlist for transmit, currently not for client use
* @rx_sg: Scatterlist for receive, currently not for client use
@ -793,6 +795,7 @@ struct spi_transfer {
u8 bits_per_word;
u16 delay_usecs;
u32 speed_hz;
u16 word_delay;
struct list_head transfer_list;
};