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

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Message-Id: <E1bIasr-0001EN-6Z@finisterre>
Date:	Thu, 30 Jun 2016 13:15:53 +0100
From:	Mark Brown <broonie@...nel.org>
To:	Andi Shyti <andi.shyti@...sung.com>
Cc:	Mark Brown <broonie@...nel.org>, Kukjin Kim <kgene@...nel.org>,
	Krzysztof Kozlowski <k.kozlowski@...sung.com>,
	Mark Brown <broonie@...nel.org>,
	Jaehoon Chung <jh80.chung@...sung.com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-samsung-soc@...r.kernel.org, linux-spi@...r.kernel.org,
	linux-kernel@...r.kernel.org, Andi Shyti <andi@...zian.org>
Subject: Applied "spi: s3c64xx: consider the case when the CS line is not connected" to the spi tree

The patch

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

has been applied to the spi tree at

   git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git 

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.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

>From a92e7c3d82a1313ab1954e5cdfd8f04efdb4ca78 Mon Sep 17 00:00:00 2001
From: Andi Shyti <andi.shyti@...sung.com>
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 <andi.shyti@...sung.com>
Signed-off-by: Mark Brown <broonie@...nel.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 --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;
-- 
2.8.1