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spi: imx: Implement support for CS_WORD

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This only works when the native chipselect is in use. On a board with a
Ti ADS7950 8 channel ADC. This patch reduces the time to read out all
channels once from 280 us to 20 us.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20210727124226.5571-1-u.kleine-koenig@pengutronix.de
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Uwe Kleine-König 2021-07-27 14:42:26 +02:00 committed by Mark Brown
parent e3aa9acc71
commit 6e95b23a5b
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1 changed files with 10 additions and 0 deletions
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10
drivers/spi/spi-imx.c
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@ -1176,6 +1176,7 @@ static int spi_imx_setupxfer(struct spi_device *spi,
* dynamic_burst in that case.
*/
if (spi_imx->devtype_data->dynamic_burst && !spi_imx->slave_mode &&
!(spi->mode & SPI_CS_WORD) &&
(spi_imx->bits_per_word == 8 ||
spi_imx->bits_per_word == 16 ||
spi_imx->bits_per_word == 32)) {
@ -1611,6 +1612,15 @@ static int spi_imx_probe(struct platform_device *pdev)
is_imx53_ecspi(spi_imx))
spi_imx->bitbang.master->mode_bits |= SPI_LOOP | SPI_READY;
if (is_imx51_ecspi(spi_imx) &&
device_property_read_u32(&pdev->dev, "cs-gpios", NULL))
/*
* When using HW-CS implementing SPI_CS_WORD can be done by just
* setting the burst length to the word size. This is
* considerably faster than manually controlling the CS.
*/
spi_imx->bitbang.master->mode_bits |= SPI_CS_WORD;
spi_imx->spi_drctl = spi_drctl;
init_completion(&spi_imx->xfer_done);