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spi: Introduce spi-cs-setup-ns property

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SPI NOR flashes have specific cs-setup time requirements without which
they can't work at frequencies close to their maximum supported frequency,
as they miss the first bits of the instruction command. Unrecognized
commands are ignored, thus the flash will be unresponsive. Introduce the
spi-cs-setup-ns property to allow spi devices to specify their cs setup
time.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Link: https://lore.kernel.org/r/20221117105249.115649-3-tudor.ambarus@microchip.com
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Tudor Ambarus 2022-11-17 12:52:43 +02:00 committed by Mark Brown
parent f6c911f330
commit 33a2fde5f7
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1 changed files with 6 additions and 0 deletions
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6
drivers/spi/spi.c
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@ -2224,6 +2224,7 @@ static int of_spi_parse_dt(struct spi_controller *ctlr, struct spi_device *spi,
struct device_node *nc) struct device_node *nc)
{ {
u32 value; u32 value;
u16 cs_setup;
int rc; int rc;
/* Mode (clock phase/polarity/etc.) */ /* Mode (clock phase/polarity/etc.) */
@ -2309,6 +2310,11 @@ static int of_spi_parse_dt(struct spi_controller *ctlr, struct spi_device *spi,
if (!of_property_read_u32(nc, "spi-max-frequency", &value)) if (!of_property_read_u32(nc, "spi-max-frequency", &value))
spi->max_speed_hz = value; spi->max_speed_hz = value;
if (!of_property_read_u16(nc, "spi-cs-setup-ns", &cs_setup)) {
spi->cs_setup.value = cs_setup;
spi->cs_setup.unit = SPI_DELAY_UNIT_NSECS;
}
return 0; return 0;
} }