From a92e7c3d82a1313ab1954e5cdfd8f04efdb4ca78 Mon Sep 17 00:00:00 2001 From: Andi Shyti Date: Tue, 28 Jun 2016 11:41:12 +0900 Subject: [PATCH] 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 Signed-off-by: Mark Brown --- Documentation/devicetree/bindings/spi/spi-samsung.txt | 3 +++ drivers/spi/spi-s3c64xx.c | 9 ++++++++- include/linux/platform_data/spi-s3c64xx.h | 1 + 3 files changed, 12 insertions(+), 1 deletion(-) diff --git a/Documentation/devicetree/bindings/spi/spi-samsung.txt b/Documentation/devicetree/bindings/spi/spi-samsung.txt index 6dbdeb3c361a..930bc7349271 100644 --- a/Documentation/devicetree/bindings/spi/spi-samsung.txt +++ b/Documentation/devicetree/bindings/spi/spi-samsung.txt @@ -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 diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c index 972367d5c7f2..14269b07804c 100644 --- a/drivers/spi/spi-s3c64xx.c +++ b/drivers/spi/spi-s3c64xx.c @@ -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 diff --git a/include/linux/platform_data/spi-s3c64xx.h b/include/linux/platform_data/spi-s3c64xx.h index fb5625bcca9a..5c1e21c87270 100644 --- a/include/linux/platform_data/spi-s3c64xx.h +++ b/include/linux/platform_data/spi-s3c64xx.h @@ -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; -- 2.39.5