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spi: a3700: Set frequency limits at startup 

Armada 3700 SPI controller has an internal clock divider which can
divide the parent clock frequency by up to 30.

This patch sets the limits in the spi_controller fields so that we can
detect when a non-supported frequency is requested by a device for a
transfer.

Signed-off-by: Maxime Chevallier <maxime.chevallier@smile.fr>
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Maxime Chevallier 2018-01-17 17:15:26 +01:00 committed by Mark Brown
parent 44a5f423e7
commit abf3a49e50
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1 changed files with 7 additions and 0 deletions
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7
drivers/spi/spi-armada-3700.c
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@ -27,6 +27,8 @@
#define DRIVER_NAME "armada_3700_spi"
#define A3700_SPI_MAX_SPEED_HZ 100000000
#define A3700_SPI_MAX_PRESCALE 30
#define A3700_SPI_TIMEOUT 10
/* SPI Register Offest */
@ -815,6 +817,11 @@ static int a3700_spi_probe(struct platform_device *pdev)
goto error;
}
master->max_speed_hz = min_t(unsigned long, A3700_SPI_MAX_SPEED_HZ,
clk_get_rate(spi->clk));
master->min_speed_hz = DIV_ROUND_UP(clk_get_rate(spi->clk),
A3700_SPI_MAX_PRESCALE);
ret = a3700_spi_init(spi);
if (ret)
goto error_clk;