diff mbox

Applied "spi: s3c64xx: consider the case when the CS line is not connected" to the spi tree

Message ID E1bIasr-0001EN-6Z@finisterre (mailing list archive)
State Not Applicable
Headers show

Commit Message

Mark Brown June 30, 2016, 12:15 p.m. UTC
The patch

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

has been applied to the spi tree at


All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

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From a92e7c3d82a1313ab1954e5cdfd8f04efdb4ca78 Mon Sep 17 00:00:00 2001
From: Andi Shyti <andi.shyti@samsung.com>
Date: Tue, 28 Jun 2016 11:41:12 +0900
Subject: [PATCH] spi: s3c64xx: consider the case when the CS line is not

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>
 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 mbox


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 =
+	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;
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;