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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: Andi Shyti <andi.shyti@samsung.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
hifive-unleashed-5.1
Andi Shyti 2016-06-28 11:41:12 +09:00 committed by Mark Brown
parent aa4964c4eb
commit a92e7c3d82
3 changed files with 12 additions and 1 deletions
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3
Documentation/devicetree/bindings/spi/spi-samsung.txt
View File

@ -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

9
drivers/spi/spi-s3c64xx.c
View File

@ -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

1
include/linux/platform_data/spi-s3c64xx.h
View File

@ -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;