Commit a92e7c3d authored by Andi Shyti's avatar Andi Shyti Committed by Mark Brown
Browse files

spi: s3c64xx: consider the case when the CS line is not connected 



When the CS line is not connected, it is not needed to enable or
disable the chip selection functionality from the s3c64xx
devices in order to perform a transfer.
Set the CS controller logically always enabled already during
initialization (by writing '0' in the S3C64XX_SPI_SLAVE_SEL
register) and never disable it.

Signed-off-by: default avatarAndi Shyti <andi.shyti@samsung.com>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent aa4964c4

Documentation/devicetree/bindings/spi/spi-samsung.txt

+3 −0
Original line number Diff line number Diff line
@@ -40,6 +40,9 @@ Optional Board Specific Properties: 


- cs-gpios: should specify GPIOs used for chipselects (see spi-bus.txt)



- no-cs-readback: the CS line is disconnected, therefore the device should not

  operate based on CS signalling.



SPI Controller specific data in SPI slave nodes:



- The spi slave nodes should provide the following information which is required

drivers/spi/spi-s3c64xx.c

+8 −1
Original line number Diff line number Diff line
@@ -315,6 +315,9 @@ static void s3c64xx_spi_set_cs(struct spi_device *spi, bool enable) 
	struct s3c64xx_spi_driver_data *sdd =

					spi_master_get_devdata(spi->master);



	if (sdd->cntrlr_info->no_cs)

		return;



	if (enable) {

		if (!(sdd->port_conf->quirks & S3C64XX_SPI_QUIRK_CS_AUTO)) {

			writel(0, sdd->regs + S3C64XX_SPI_SLAVE_SEL);
@@ -960,7 +963,9 @@ static void s3c64xx_spi_hwinit(struct s3c64xx_spi_driver_data *sdd, int channel) 


	sdd->cur_speed = 0;



	if (!(sdd->port_conf->quirks & S3C64XX_SPI_QUIRK_CS_AUTO))

	if (sci->no_cs)

		writel(0, sdd->regs + S3C64XX_SPI_SLAVE_SEL);

	else if (!(sdd->port_conf->quirks & S3C64XX_SPI_QUIRK_CS_AUTO))

		writel(S3C64XX_SPI_SLAVE_SIG_INACT, sdd->regs + S3C64XX_SPI_SLAVE_SEL);



	/* Disable Interrupts - we use Polling if not DMA mode */
@@ -1015,6 +1020,8 @@ static struct s3c64xx_spi_info *s3c64xx_spi_parse_dt(struct device *dev) 
		sci->num_cs = temp;

	}



	sci->no_cs = of_property_read_bool(dev->of_node, "broken-cs");



	return sci;

}

#else

include/linux/platform_data/spi-s3c64xx.h

+1 −0
Original line number Diff line number Diff line
@@ -38,6 +38,7 @@ struct s3c64xx_spi_csinfo { 
struct s3c64xx_spi_info {

	int src_clk_nr;

	int num_cs;

	bool no_cs;

	int (*cfg_gpio)(void);

	dma_filter_fn filter;

	void *dma_tx;

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