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spi: core,atmel: convert word_delay_usecs -> word_delay for spi_device

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This change does a conversion from the `word_delay_usecs` -> `word_delay`
for the `spi_device` struct.

This allows users to specify inter-word delays in other unit types
(nano-seconds or clock cycles), depending on how users want.

The Atmel SPI driver is the only current user of the `word_delay_usecs`
field (from the `spi_device` struct).
So, it needed a slight conversion to use the `word_delay` as an `spi_delay`
struct.

In SPI core, the only required mechanism is to update the `word_delay`
information per `spi_transfer`. This requires a bit more logic than before,
because it needs that both delays be converted to a common unit
(nano-seconds) for comparison.

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20190926105147.7839-8-alexandru.ardelean@analog.com
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Alexandru Ardelean
2019-09-26 13:51:35 +03:00
committed by Mark Brown
parent ec3fa72fa8
commit 6c613f68aa
3 changed files with 48 additions and 9 deletions
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7
include/linux/spi/spi.h
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@@ -139,7 +139,7 @@ extern int spi_delay_exec(struct spi_delay *_delay, struct spi_transfer *xfer);
* the spi_master.
* @cs_gpiod: gpio descriptor of the chipselect line (optional, NULL when
* not using a GPIO line)
* @word_delay_usecs: microsecond delay to be inserted between consecutive
* @word_delay: delay to be inserted between consecutive
* words of a transfer
*
* @statistics: statistics for the spi_device
@@ -189,7 +189,7 @@ struct spi_device {
const char *driver_override;
int cs_gpio; /* LEGACY: chip select gpio */
struct gpio_desc *cs_gpiod; /* chip select gpio desc */
uint8_t word_delay_usecs; /* inter-word delay */
struct spi_delay word_delay; /* inter-word delay */
/* the statistics */
struct spi_statistics statistics;
@@ -781,8 +781,6 @@ 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_usecs: microseconds to inter word delay after each word size
* (set by bits_per_word) transmission.
* @word_delay: inter word delay to be introduced after each word size
* (set by bits_per_word) transmission.
* @effective_speed_hz: the effective SCK-speed that was used to
@@ -897,7 +895,6 @@ struct spi_transfer {
#define SPI_NBITS_DUAL 0x02 /* 2bits transfer */
#define SPI_NBITS_QUAD 0x04 /* 4bits transfer */
u8 bits_per_word;
u8 word_delay_usecs;
u16 delay_usecs;
struct spi_delay cs_change_delay;
struct spi_delay word_delay;