[PATCH 0/4] spi: sh-msiof: Multi-slave enhancements

[PATCH 0/4] spi: sh-msiof: Multi-slave enhancements

[Geert Uytterhoeven]

	Hi Mark², Rob,

This patch series enhances the Renesas MSIOF SPI controller driver for
multiple SPI slave devices.

The first patch fixes the classical pitfall of writing to configuration
registers from the spi_master.setup() callback, where possible.
The second patch extends support from 1 to 3 native chip selects,
The third patch fixes the use of GPIOs as chip selects on modern
platform using DT instead of board code.
The last patch documents hardware limitations related to chip selects,
to guide board designers and DTS writers.

This has been tested with:
  - Three 25LC040 SPI EEPROMs, using GPIO chip selects due to MSIOF
    hardware limitations (verified with a logic analyzer),
  - Multiple 74HC595 shift registers feeding lots of blinkenlights,
    using only native chipselects, only GPIO chip selects, and a healthy
    mix of both.

Thanks for your comments!

Geert Uytterhoeven (4):
  spi: sh-msiof: Avoid writing to registers from spi_master.setup()
  spi: sh-msiof: Extend support to 3 native chip selects
  spi: sh-msiof: Implement cs-gpios configuration
  spi: sh-msiof: Document hardware limitations related to chip selects

 Documentation/devicetree/bindings/spi/sh-msiof.txt |  16 ++-
 drivers/spi/spi-sh-msiof.c                         | 111 +++++++++++++++++----
 2 files changed, 107 insertions(+), 20 deletions(-)

-- 
2.7.4

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert-Td1EMuHUCqxL1ZNQvxDV9g@public.gmane.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds
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[PATCH 1/4] spi: sh-msiof: Avoid writing to registers from spi_master.setup()

[Geert Uytterhoeven]

The spi_master.setup() callback must not change configuration registers,
as that could corrupt I/O that is in progress for other SPI slaves.

The only exception is the configuration of the native chip select
polarity in SPI master mode, as a wrong chip select polarity will cause
havoc during all future transfers to any other SPI slave.

Hence stop writing to registers in sh_msiof_spi_setup(), unless it is
the first call for a controller using a native chip select, or unless
native chip select polarity has changed (note that you'll loose anyway
if I/O is in progress).  Even then, only do what is strictly necessary,
instead of calling sh_msiof_spi_set_pin_regs().

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
 drivers/spi/spi-sh-msiof.c | 35 ++++++++++++++++++++++++-----------
 1 file changed, 24 insertions(+), 11 deletions(-)

diff --git a/drivers/spi/spi-sh-msiof.c b/drivers/spi/spi-sh-msiof.c
index 81a9144f5442cdb4..2704abb11ea41fd0 100644
--- a/drivers/spi/spi-sh-msiof.c
+++ b/drivers/spi/spi-sh-msiof.c
@@ -55,6 +55,8 @@ struct sh_msiof_spi_priv {
 	void *rx_dma_page;
 	dma_addr_t tx_dma_addr;
 	dma_addr_t rx_dma_addr;
+	bool native_cs_inited;
+	bool native_cs_high;
 	bool slave_aborted;
 };
 
@@ -528,8 +530,7 @@ static int sh_msiof_spi_setup(struct spi_device *spi)
 {
 	struct device_node	*np = spi->master->dev.of_node;
 	struct sh_msiof_spi_priv *p = spi_master_get_devdata(spi->master);
-
-	pm_runtime_get_sync(&p->pdev->dev);
+	u32 clr, set, tmp;
 
 	if (!np) {
 		/*
@@ -539,19 +540,31 @@ static int sh_msiof_spi_setup(struct spi_device *spi)
 		spi->cs_gpio = (uintptr_t)spi->controller_data;
 	}
 
-	/* Configure pins before deasserting CS */
-	sh_msiof_spi_set_pin_regs(p, !!(spi->mode & SPI_CPOL),
-				  !!(spi->mode & SPI_CPHA),
-				  !!(spi->mode & SPI_3WIRE),
-				  !!(spi->mode & SPI_LSB_FIRST),
-				  !!(spi->mode & SPI_CS_HIGH));
-
-	if (spi->cs_gpio >= 0)
+	if (spi->cs_gpio >= 0) {
 		gpio_set_value(spi->cs_gpio, !(spi->mode & SPI_CS_HIGH));
+		return 0;
+	}
 
+	if (spi_controller_is_slave(p->master))
+		return 0;
 
-	pm_runtime_put(&p->pdev->dev);
+	if (p->native_cs_inited &&
+	    (p->native_cs_high == !!(spi->mode & SPI_CS_HIGH)))
+		return 0;
 
+	/* Configure native chip select mode/polarity early */
+	clr = MDR1_SYNCMD_MASK;
+	set = MDR1_TRMD | TMDR1_PCON | MDR1_SYNCMD_SPI;
+	if (spi->mode & SPI_CS_HIGH)
+		clr |= BIT(MDR1_SYNCAC_SHIFT);
+	else
+		set |= BIT(MDR1_SYNCAC_SHIFT);
+	pm_runtime_get_sync(&p->pdev->dev);
+	tmp = sh_msiof_read(p, TMDR1) & ~clr;
+	sh_msiof_write(p, TMDR1, tmp | set);
+	pm_runtime_put(&p->pdev->dev);
+	p->native_cs_high = spi->mode & SPI_CS_HIGH;
+	p->native_cs_inited = true;
 	return 0;
 }
 
-- 
2.7.4

Applied "spi: sh-msiof: Avoid writing to registers from spi_master.setup()" to the spi tree

[Mark Brown]

The patch

   spi: sh-msiof: Avoid writing to registers from spi_master.setup()

has been applied to the spi tree at

   https://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 7ff0b53c4051145d1cf992d2f60987e6447eed4f Mon Sep 17 00:00:00 2001
From: Geert Uytterhoeven <geert+renesas@glider.be>
Date: Wed, 13 Dec 2017 20:05:10 +0100
Subject: [PATCH] spi: sh-msiof: Avoid writing to registers from
 spi_master.setup()

The spi_master.setup() callback must not change configuration registers,
as that could corrupt I/O that is in progress for other SPI slaves.

The only exception is the configuration of the native chip select
polarity in SPI master mode, as a wrong chip select polarity will cause
havoc during all future transfers to any other SPI slave.

Hence stop writing to registers in sh_msiof_spi_setup(), unless it is
the first call for a controller using a native chip select, or unless
native chip select polarity has changed (note that you'll loose anyway
if I/O is in progress).  Even then, only do what is strictly necessary,
instead of calling sh_msiof_spi_set_pin_regs().

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
 drivers/spi/spi-sh-msiof.c | 35 ++++++++++++++++++++++++-----------
 1 file changed, 24 insertions(+), 11 deletions(-)

diff --git a/drivers/spi/spi-sh-msiof.c b/drivers/spi/spi-sh-msiof.c
index 81a9144f5442..2704abb11ea4 100644
--- a/drivers/spi/spi-sh-msiof.c
+++ b/drivers/spi/spi-sh-msiof.c
@@ -55,6 +55,8 @@ struct sh_msiof_spi_priv {
 	void *rx_dma_page;
 	dma_addr_t tx_dma_addr;
 	dma_addr_t rx_dma_addr;
+	bool native_cs_inited;
+	bool native_cs_high;
 	bool slave_aborted;
 };
 
@@ -528,8 +530,7 @@ static int sh_msiof_spi_setup(struct spi_device *spi)
 {
 	struct device_node	*np = spi->master->dev.of_node;
 	struct sh_msiof_spi_priv *p = spi_master_get_devdata(spi->master);
-
-	pm_runtime_get_sync(&p->pdev->dev);
+	u32 clr, set, tmp;
 
 	if (!np) {
 		/*
@@ -539,19 +540,31 @@ static int sh_msiof_spi_setup(struct spi_device *spi)
 		spi->cs_gpio = (uintptr_t)spi->controller_data;
 	}
 
-	/* Configure pins before deasserting CS */
-	sh_msiof_spi_set_pin_regs(p, !!(spi->mode & SPI_CPOL),
-				  !!(spi->mode & SPI_CPHA),
-				  !!(spi->mode & SPI_3WIRE),
-				  !!(spi->mode & SPI_LSB_FIRST),
-				  !!(spi->mode & SPI_CS_HIGH));
-
-	if (spi->cs_gpio >= 0)
+	if (spi->cs_gpio >= 0) {
 		gpio_set_value(spi->cs_gpio, !(spi->mode & SPI_CS_HIGH));
+		return 0;
+	}
 
+	if (spi_controller_is_slave(p->master))
+		return 0;
 
-	pm_runtime_put(&p->pdev->dev);
+	if (p->native_cs_inited &&
+	    (p->native_cs_high == !!(spi->mode & SPI_CS_HIGH)))
+		return 0;
 
+	/* Configure native chip select mode/polarity early */
+	clr = MDR1_SYNCMD_MASK;
+	set = MDR1_TRMD | TMDR1_PCON | MDR1_SYNCMD_SPI;
+	if (spi->mode & SPI_CS_HIGH)
+		clr |= BIT(MDR1_SYNCAC_SHIFT);
+	else
+		set |= BIT(MDR1_SYNCAC_SHIFT);
+	pm_runtime_get_sync(&p->pdev->dev);
+	tmp = sh_msiof_read(p, TMDR1) & ~clr;
+	sh_msiof_write(p, TMDR1, tmp | set);
+	pm_runtime_put(&p->pdev->dev);
+	p->native_cs_high = spi->mode & SPI_CS_HIGH;
+	p->native_cs_inited = true;
 	return 0;
 }
 
-- 
2.15.1

[PATCH 2/4] spi: sh-msiof: Extend support to 3 native chip selects

[Geert Uytterhoeven]

Currently only the MSIOF_SYNC signal can be used as a native chip
select.  Extend support to up to 3 native chipselects using the
MSIOF_SS1 and MSIOF_SS2 signals.

Inspired by a patch in the BSP by Hiromitsu Yamasaki.

Signed-off-by: Geert Uytterhoeven <geert+renesas-gXvu3+zWzMSzQB+pC5nmwQ@public.gmane.org>
---
 Documentation/devicetree/bindings/spi/sh-msiof.txt |  6 +++++-
 drivers/spi/spi-sh-msiof.c                         | 18 +++++++++++++-----
 2 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/Documentation/devicetree/bindings/spi/sh-msiof.txt b/Documentation/devicetree/bindings/spi/sh-msiof.txt
index bdd83959019c7883..bc8c16a6cfc82685 100644
--- a/Documentation/devicetree/bindings/spi/sh-msiof.txt
+++ b/Documentation/devicetree/bindings/spi/sh-msiof.txt
@@ -36,7 +36,11 @@ Required properties:
 
 Optional properties:
 - clocks               : Must contain a reference to the functional clock.
-- num-cs               : Total number of chip-selects (default is 1)
+- num-cs               : Total number of chip selects (default is 1).
+			 Up to 3 native chip selects are supported:
+			   0: MSIOF_SYNC
+			   1: MSIOF_SS1
+			   2: MSIOF_SS2
 - dmas                 : Must contain a list of two references to DMA
 			 specifiers, one for transmission, and one for
 			 reception.
diff --git a/drivers/spi/spi-sh-msiof.c b/drivers/spi/spi-sh-msiof.c
index 2704abb11ea41fd0..9bdc292aa050cb16 100644
--- a/drivers/spi/spi-sh-msiof.c
+++ b/drivers/spi/spi-sh-msiof.c
@@ -60,6 +60,8 @@ struct sh_msiof_spi_priv {
 	bool slave_aborted;
 };
 
+#define MAX_SS	3	/* Maximum number of native chip selects */
+
 #define TMDR1	0x00	/* Transmit Mode Register 1 */
 #define TMDR2	0x04	/* Transmit Mode Register 2 */
 #define TMDR3	0x08	/* Transmit Mode Register 3 */
@@ -93,6 +95,8 @@ struct sh_msiof_spi_priv {
 #define MDR1_XXSTP	 0x00000001 /* Transmission/Reception Stop on FIFO */
 /* TMDR1 */
 #define TMDR1_PCON	 0x40000000 /* Transfer Signal Connection */
+#define TMDR1_SYNCCH_MASK 0xc000000 /* Synchronization Signal Channel Select */
+#define TMDR1_SYNCCH_SHIFT	 26 /* 0=MSIOF_SYNC, 1=MSIOF_SS1, 2=MSIOF_SS2 */
 
 /* TMDR2 and RMDR2 */
 #define MDR2_BITLEN1(i)	(((i) - 1) << 24) /* Data Size (8-32 bits) */
@@ -326,7 +330,7 @@ static u32 sh_msiof_spi_get_dtdl_and_syncdl(struct sh_msiof_spi_priv *p)
 	return val;
 }
 
-static void sh_msiof_spi_set_pin_regs(struct sh_msiof_spi_priv *p,
+static void sh_msiof_spi_set_pin_regs(struct sh_msiof_spi_priv *p, u32 ss,
 				      u32 cpol, u32 cpha,
 				      u32 tx_hi_z, u32 lsb_first, u32 cs_high)
 {
@@ -344,10 +348,13 @@ static void sh_msiof_spi_set_pin_regs(struct sh_msiof_spi_priv *p,
 	tmp |= !cs_high << MDR1_SYNCAC_SHIFT;
 	tmp |= lsb_first << MDR1_BITLSB_SHIFT;
 	tmp |= sh_msiof_spi_get_dtdl_and_syncdl(p);
-	if (spi_controller_is_slave(p->master))
+	if (spi_controller_is_slave(p->master)) {
 		sh_msiof_write(p, TMDR1, tmp | TMDR1_PCON);
-	else
-		sh_msiof_write(p, TMDR1, tmp | MDR1_TRMD | TMDR1_PCON);
+	} else {
+		sh_msiof_write(p, TMDR1,
+			       tmp | MDR1_TRMD | TMDR1_PCON |
+			       (ss < MAX_SS ? ss : 0) << TMDR1_SYNCCH_SHIFT);
+	}
 	if (p->master->flags & SPI_MASTER_MUST_TX) {
 		/* These bits are reserved if RX needs TX */
 		tmp &= ~0x0000ffff;
@@ -575,7 +582,8 @@ static int sh_msiof_prepare_message(struct spi_master *master,
 	const struct spi_device *spi = msg->spi;
 
 	/* Configure pins before asserting CS */
-	sh_msiof_spi_set_pin_regs(p, !!(spi->mode & SPI_CPOL),
+	sh_msiof_spi_set_pin_regs(p, spi->chip_select,
+				  !!(spi->mode & SPI_CPOL),
 				  !!(spi->mode & SPI_CPHA),
 				  !!(spi->mode & SPI_3WIRE),
 				  !!(spi->mode & SPI_LSB_FIRST),
-- 
2.7.4

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Applied "spi: sh-msiof: Extend support to 3 native chip selects" to the spi tree

[Mark Brown]

The patch

   spi: sh-msiof: Extend support to 3 native chip selects

has been applied to the spi tree at

   https://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 9cce882bedd2768dc251b73f2ad86a9bfcfd9fc7 Mon Sep 17 00:00:00 2001
From: Geert Uytterhoeven <geert+renesas@glider.be>
Date: Wed, 13 Dec 2017 20:05:11 +0100
Subject: [PATCH] spi: sh-msiof: Extend support to 3 native chip selects

Currently only the MSIOF_SYNC signal can be used as a native chip
select.  Extend support to up to 3 native chipselects using the
MSIOF_SS1 and MSIOF_SS2 signals.

Inspired by a patch in the BSP by Hiromitsu Yamasaki.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
 Documentation/devicetree/bindings/spi/sh-msiof.txt |  6 +++++-
 drivers/spi/spi-sh-msiof.c                         | 18 +++++++++++++-----
 2 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/Documentation/devicetree/bindings/spi/sh-msiof.txt b/Documentation/devicetree/bindings/spi/sh-msiof.txt
index bdd83959019c..bc8c16a6cfc8 100644
--- a/Documentation/devicetree/bindings/spi/sh-msiof.txt
+++ b/Documentation/devicetree/bindings/spi/sh-msiof.txt
@@ -36,7 +36,11 @@ Required properties:
 
 Optional properties:
 - clocks               : Must contain a reference to the functional clock.
-- num-cs               : Total number of chip-selects (default is 1)
+- num-cs               : Total number of chip selects (default is 1).
+			 Up to 3 native chip selects are supported:
+			   0: MSIOF_SYNC
+			   1: MSIOF_SS1
+			   2: MSIOF_SS2
 - dmas                 : Must contain a list of two references to DMA
 			 specifiers, one for transmission, and one for
 			 reception.
diff --git a/drivers/spi/spi-sh-msiof.c b/drivers/spi/spi-sh-msiof.c
index 2704abb11ea4..9bdc292aa050 100644
--- a/drivers/spi/spi-sh-msiof.c
+++ b/drivers/spi/spi-sh-msiof.c
@@ -60,6 +60,8 @@ struct sh_msiof_spi_priv {
 	bool slave_aborted;
 };
 
+#define MAX_SS	3	/* Maximum number of native chip selects */
+
 #define TMDR1	0x00	/* Transmit Mode Register 1 */
 #define TMDR2	0x04	/* Transmit Mode Register 2 */
 #define TMDR3	0x08	/* Transmit Mode Register 3 */
@@ -93,6 +95,8 @@ struct sh_msiof_spi_priv {
 #define MDR1_XXSTP	 0x00000001 /* Transmission/Reception Stop on FIFO */
 /* TMDR1 */
 #define TMDR1_PCON	 0x40000000 /* Transfer Signal Connection */
+#define TMDR1_SYNCCH_MASK 0xc000000 /* Synchronization Signal Channel Select */
+#define TMDR1_SYNCCH_SHIFT	 26 /* 0=MSIOF_SYNC, 1=MSIOF_SS1, 2=MSIOF_SS2 */
 
 /* TMDR2 and RMDR2 */
 #define MDR2_BITLEN1(i)	(((i) - 1) << 24) /* Data Size (8-32 bits) */
@@ -326,7 +330,7 @@ static u32 sh_msiof_spi_get_dtdl_and_syncdl(struct sh_msiof_spi_priv *p)
 	return val;
 }
 
-static void sh_msiof_spi_set_pin_regs(struct sh_msiof_spi_priv *p,
+static void sh_msiof_spi_set_pin_regs(struct sh_msiof_spi_priv *p, u32 ss,
 				      u32 cpol, u32 cpha,
 				      u32 tx_hi_z, u32 lsb_first, u32 cs_high)
 {
@@ -344,10 +348,13 @@ static void sh_msiof_spi_set_pin_regs(struct sh_msiof_spi_priv *p,
 	tmp |= !cs_high << MDR1_SYNCAC_SHIFT;
 	tmp |= lsb_first << MDR1_BITLSB_SHIFT;
 	tmp |= sh_msiof_spi_get_dtdl_and_syncdl(p);
-	if (spi_controller_is_slave(p->master))
+	if (spi_controller_is_slave(p->master)) {
 		sh_msiof_write(p, TMDR1, tmp | TMDR1_PCON);
-	else
-		sh_msiof_write(p, TMDR1, tmp | MDR1_TRMD | TMDR1_PCON);
+	} else {
+		sh_msiof_write(p, TMDR1,
+			       tmp | MDR1_TRMD | TMDR1_PCON |
+			       (ss < MAX_SS ? ss : 0) << TMDR1_SYNCCH_SHIFT);
+	}
 	if (p->master->flags & SPI_MASTER_MUST_TX) {
 		/* These bits are reserved if RX needs TX */
 		tmp &= ~0x0000ffff;
@@ -575,7 +582,8 @@ static int sh_msiof_prepare_message(struct spi_master *master,
 	const struct spi_device *spi = msg->spi;
 
 	/* Configure pins before asserting CS */
-	sh_msiof_spi_set_pin_regs(p, !!(spi->mode & SPI_CPOL),
+	sh_msiof_spi_set_pin_regs(p, spi->chip_select,
+				  !!(spi->mode & SPI_CPOL),
 				  !!(spi->mode & SPI_CPHA),
 				  !!(spi->mode & SPI_3WIRE),
 				  !!(spi->mode & SPI_LSB_FIRST),
-- 
2.15.1

[PATCH 3/4] spi: sh-msiof: Implement cs-gpios configuration

[Geert Uytterhoeven]

The current support for GPIO chip selects assumes the GPIOs have been
configured by platform code or the boot loader.  This includes pinmux
setup and GPIO direction.  Hence it does not work as expected when just
described in DT using the "cs-gpios" property.

Fix this by:
  1. using devm_gpiod_get_index() to request the GPIO, and thus
     configure pinmux, if needed,
  2. configuring the GPIO direction is the spi_master.setup() callback.

Use gpio_is_valid() instead of a check on positive numbers.

Note that when using GPIO chip selects, at least one native chip select
must be left unused, as that native chip select will be driven anyway,
and (global) native chip select polarity must be taken into account.

Signed-off-by: Geert Uytterhoeven <geert+renesas-gXvu3+zWzMSzQB+pC5nmwQ@public.gmane.org>
---
 drivers/spi/spi-sh-msiof.c | 66 +++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 59 insertions(+), 7 deletions(-)

diff --git a/drivers/spi/spi-sh-msiof.c b/drivers/spi/spi-sh-msiof.c
index 9bdc292aa050cb16..8aa5c7b910d9ca93 100644
--- a/drivers/spi/spi-sh-msiof.c
+++ b/drivers/spi/spi-sh-msiof.c
@@ -19,6 +19,7 @@
 #include <linux/dmaengine.h>
 #include <linux/err.h>
 #include <linux/gpio.h>
+#include <linux/gpio/consumer.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/kernel.h>
@@ -55,6 +56,7 @@ struct sh_msiof_spi_priv {
 	void *rx_dma_page;
 	dma_addr_t tx_dma_addr;
 	dma_addr_t rx_dma_addr;
+	unsigned short unused_ss;
 	bool native_cs_inited;
 	bool native_cs_high;
 	bool slave_aborted;
@@ -547,8 +549,8 @@ static int sh_msiof_spi_setup(struct spi_device *spi)
 		spi->cs_gpio = (uintptr_t)spi->controller_data;
 	}
 
-	if (spi->cs_gpio >= 0) {
-		gpio_set_value(spi->cs_gpio, !(spi->mode & SPI_CS_HIGH));
+	if (gpio_is_valid(spi->cs_gpio)) {
+		gpio_direction_output(spi->cs_gpio, !(spi->mode & SPI_CS_HIGH));
 		return 0;
 	}
 
@@ -580,14 +582,20 @@ static int sh_msiof_prepare_message(struct spi_master *master,
 {
 	struct sh_msiof_spi_priv *p = spi_master_get_devdata(master);
 	const struct spi_device *spi = msg->spi;
+	u32 ss, cs_high;
 
 	/* Configure pins before asserting CS */
-	sh_msiof_spi_set_pin_regs(p, spi->chip_select,
-				  !!(spi->mode & SPI_CPOL),
+	if (gpio_is_valid(spi->cs_gpio)) {
+		ss = p->unused_ss;
+		cs_high = p->native_cs_high;
+	} else {
+		ss = spi->chip_select;
+		cs_high = !!(spi->mode & SPI_CS_HIGH);
+	}
+	sh_msiof_spi_set_pin_regs(p, ss, !!(spi->mode & SPI_CPOL),
 				  !!(spi->mode & SPI_CPHA),
 				  !!(spi->mode & SPI_3WIRE),
-				  !!(spi->mode & SPI_LSB_FIRST),
-				  !!(spi->mode & SPI_CS_HIGH));
+				  !!(spi->mode & SPI_LSB_FIRST), cs_high);
 	return 0;
 }
 
@@ -1091,6 +1099,45 @@ static struct sh_msiof_spi_info *sh_msiof_spi_parse_dt(struct device *dev)
 }
 #endif
 
+static int sh_msiof_get_cs_gpios(struct sh_msiof_spi_priv *p)
+{
+	struct device *dev = &p->pdev->dev;
+	unsigned int used_ss_mask = 0;
+	unsigned int cs_gpios = 0;
+	unsigned int num_cs, i;
+	int ret;
+
+	ret = gpiod_count(dev, "cs");
+	if (ret <= 0)
+		return 0;
+
+	num_cs = max_t(unsigned int, ret, p->master->num_chipselect);
+	for (i = 0; i < num_cs; i++) {
+		struct gpio_desc *gpiod;
+
+		gpiod = devm_gpiod_get_index(dev, "cs", i, GPIOD_ASIS);
+		if (!IS_ERR(gpiod)) {
+			cs_gpios++;
+			continue;
+		}
+
+		if (PTR_ERR(gpiod) != -ENOENT)
+			return PTR_ERR(gpiod);
+
+		if (i >= MAX_SS) {
+			dev_err(dev, "Invalid native chip select %d\n", i);
+			return -EINVAL;
+		}
+		used_ss_mask |= BIT(i);
+	}
+	p->unused_ss = ffz(used_ss_mask);
+	if (cs_gpios && p->unused_ss >= MAX_SS) {
+		dev_err(dev, "No unused native chip select available\n");
+		return -EINVAL;
+	}
+	return 0;
+}
+
 static struct dma_chan *sh_msiof_request_dma_chan(struct device *dev,
 	enum dma_transfer_direction dir, unsigned int id, dma_addr_t port_addr)
 {
@@ -1304,13 +1351,18 @@ static int sh_msiof_spi_probe(struct platform_device *pdev)
 	if (p->info->rx_fifo_override)
 		p->rx_fifo_size = p->info->rx_fifo_override;
 
+	/* Setup GPIO chip selects */
+	master->num_chipselect = p->info->num_chipselect;
+	ret = sh_msiof_get_cs_gpios(p);
+	if (ret)
+		goto err1;
+
 	/* init master code */
 	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
 	master->mode_bits |= SPI_LSB_FIRST | SPI_3WIRE;
 	master->flags = chipdata->master_flags;
 	master->bus_num = pdev->id;
 	master->dev.of_node = pdev->dev.of_node;
-	master->num_chipselect = p->info->num_chipselect;
 	master->setup = sh_msiof_spi_setup;
 	master->prepare_message = sh_msiof_prepare_message;
 	master->slave_abort = sh_msiof_slave_abort;
-- 
2.7.4

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Applied "spi: sh-msiof: Implement cs-gpios configuration" to the spi tree

[Mark Brown]

The patch

   spi: sh-msiof: Implement cs-gpios configuration

has been applied to the spi tree at

   https://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 b8761434bdec32fa46a644c26a12d16a9b0f58d8 Mon Sep 17 00:00:00 2001
From: Geert Uytterhoeven <geert+renesas@glider.be>
Date: Wed, 13 Dec 2017 20:05:12 +0100
Subject: [PATCH] spi: sh-msiof: Implement cs-gpios configuration

The current support for GPIO chip selects assumes the GPIOs have been
configured by platform code or the boot loader.  This includes pinmux
setup and GPIO direction.  Hence it does not work as expected when just
described in DT using the "cs-gpios" property.

Fix this by:
  1. using devm_gpiod_get_index() to request the GPIO, and thus
     configure pinmux, if needed,
  2. configuring the GPIO direction is the spi_master.setup() callback.

Use gpio_is_valid() instead of a check on positive numbers.

Note that when using GPIO chip selects, at least one native chip select
must be left unused, as that native chip select will be driven anyway,
and (global) native chip select polarity must be taken into account.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
 drivers/spi/spi-sh-msiof.c | 66 +++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 59 insertions(+), 7 deletions(-)

diff --git a/drivers/spi/spi-sh-msiof.c b/drivers/spi/spi-sh-msiof.c
index 9bdc292aa050..8aa5c7b910d9 100644
--- a/drivers/spi/spi-sh-msiof.c
+++ b/drivers/spi/spi-sh-msiof.c
@@ -19,6 +19,7 @@
 #include <linux/dmaengine.h>
 #include <linux/err.h>
 #include <linux/gpio.h>
+#include <linux/gpio/consumer.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/kernel.h>
@@ -55,6 +56,7 @@ struct sh_msiof_spi_priv {
 	void *rx_dma_page;
 	dma_addr_t tx_dma_addr;
 	dma_addr_t rx_dma_addr;
+	unsigned short unused_ss;
 	bool native_cs_inited;
 	bool native_cs_high;
 	bool slave_aborted;
@@ -547,8 +549,8 @@ static int sh_msiof_spi_setup(struct spi_device *spi)
 		spi->cs_gpio = (uintptr_t)spi->controller_data;
 	}
 
-	if (spi->cs_gpio >= 0) {
-		gpio_set_value(spi->cs_gpio, !(spi->mode & SPI_CS_HIGH));
+	if (gpio_is_valid(spi->cs_gpio)) {
+		gpio_direction_output(spi->cs_gpio, !(spi->mode & SPI_CS_HIGH));
 		return 0;
 	}
 
@@ -580,14 +582,20 @@ static int sh_msiof_prepare_message(struct spi_master *master,
 {
 	struct sh_msiof_spi_priv *p = spi_master_get_devdata(master);
 	const struct spi_device *spi = msg->spi;
+	u32 ss, cs_high;
 
 	/* Configure pins before asserting CS */
-	sh_msiof_spi_set_pin_regs(p, spi->chip_select,
-				  !!(spi->mode & SPI_CPOL),
+	if (gpio_is_valid(spi->cs_gpio)) {
+		ss = p->unused_ss;
+		cs_high = p->native_cs_high;
+	} else {
+		ss = spi->chip_select;
+		cs_high = !!(spi->mode & SPI_CS_HIGH);
+	}
+	sh_msiof_spi_set_pin_regs(p, ss, !!(spi->mode & SPI_CPOL),
 				  !!(spi->mode & SPI_CPHA),
 				  !!(spi->mode & SPI_3WIRE),
-				  !!(spi->mode & SPI_LSB_FIRST),
-				  !!(spi->mode & SPI_CS_HIGH));
+				  !!(spi->mode & SPI_LSB_FIRST), cs_high);
 	return 0;
 }
 
@@ -1091,6 +1099,45 @@ static struct sh_msiof_spi_info *sh_msiof_spi_parse_dt(struct device *dev)
 }
 #endif
 
+static int sh_msiof_get_cs_gpios(struct sh_msiof_spi_priv *p)
+{
+	struct device *dev = &p->pdev->dev;
+	unsigned int used_ss_mask = 0;
+	unsigned int cs_gpios = 0;
+	unsigned int num_cs, i;
+	int ret;
+
+	ret = gpiod_count(dev, "cs");
+	if (ret <= 0)
+		return 0;
+
+	num_cs = max_t(unsigned int, ret, p->master->num_chipselect);
+	for (i = 0; i < num_cs; i++) {
+		struct gpio_desc *gpiod;
+
+		gpiod = devm_gpiod_get_index(dev, "cs", i, GPIOD_ASIS);
+		if (!IS_ERR(gpiod)) {
+			cs_gpios++;
+			continue;
+		}
+
+		if (PTR_ERR(gpiod) != -ENOENT)
+			return PTR_ERR(gpiod);
+
+		if (i >= MAX_SS) {
+			dev_err(dev, "Invalid native chip select %d\n", i);
+			return -EINVAL;
+		}
+		used_ss_mask |= BIT(i);
+	}
+	p->unused_ss = ffz(used_ss_mask);
+	if (cs_gpios && p->unused_ss >= MAX_SS) {
+		dev_err(dev, "No unused native chip select available\n");
+		return -EINVAL;
+	}
+	return 0;
+}
+
 static struct dma_chan *sh_msiof_request_dma_chan(struct device *dev,
 	enum dma_transfer_direction dir, unsigned int id, dma_addr_t port_addr)
 {
@@ -1304,13 +1351,18 @@ static int sh_msiof_spi_probe(struct platform_device *pdev)
 	if (p->info->rx_fifo_override)
 		p->rx_fifo_size = p->info->rx_fifo_override;
 
+	/* Setup GPIO chip selects */
+	master->num_chipselect = p->info->num_chipselect;
+	ret = sh_msiof_get_cs_gpios(p);
+	if (ret)
+		goto err1;
+
 	/* init master code */
 	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
 	master->mode_bits |= SPI_LSB_FIRST | SPI_3WIRE;
 	master->flags = chipdata->master_flags;
 	master->bus_num = pdev->id;
 	master->dev.of_node = pdev->dev.of_node;
-	master->num_chipselect = p->info->num_chipselect;
 	master->setup = sh_msiof_spi_setup;
 	master->prepare_message = sh_msiof_prepare_message;
 	master->slave_abort = sh_msiof_slave_abort;
-- 
2.15.1

[PATCH 4/4] spi: sh-msiof: Document hardware limitations related to chip selects

[Geert Uytterhoeven]

Guide users to maintain the proper balance between native and GPIO chip
selects.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
 Documentation/devicetree/bindings/spi/sh-msiof.txt | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/Documentation/devicetree/bindings/spi/sh-msiof.txt b/Documentation/devicetree/bindings/spi/sh-msiof.txt
index bc8c16a6cfc82685..80710f0f04489174 100644
--- a/Documentation/devicetree/bindings/spi/sh-msiof.txt
+++ b/Documentation/devicetree/bindings/spi/sh-msiof.txt
@@ -41,6 +41,16 @@ Optional properties:
 			   0: MSIOF_SYNC
 			   1: MSIOF_SS1
 			   2: MSIOF_SS2
+			 Hardware limitations related to chip selects:
+			   - Native chip selects are always deasserted in
+			     between transfers that are part of the same
+			     message.  Use cs-gpios to work around this.
+			   - All slaves using native chip selects must use the
+			     same spi-cs-high configuration.  Use cs-gpios to
+			     work around this.
+			   - When using GPIO chip selects, at least one native
+			     chip select must be left unused, as it will be
+			     driven anyway.
 - dmas                 : Must contain a list of two references to DMA
 			 specifiers, one for transmission, and one for
 			 reception.
-- 
2.7.4

Re: [PATCH 4/4] spi: sh-msiof: Document hardware limitations related to chip selects

[Mark Brown]

[-- Attachment #1: Type: text/plain, Size: 375 bytes --]

On Wed, Dec 13, 2017 at 08:05:13PM +0100, Geert Uytterhoeven wrote:

> +			 Hardware limitations related to chip selects:
> +			   - Native chip selects are always deasserted in
> +			     between transfers that are part of the same
> +			     message.  Use cs-gpios to work around this.

Ideally the driver would be generating an error when it sees
multi-transfer messages.

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]

Applied "spi: sh-msiof: Document hardware limitations related to chip selects" to the spi tree

[Mark Brown]

The patch

   spi: sh-msiof: Document hardware limitations related to chip selects

has been applied to the spi tree at

   https://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 c99182f73cce7926c623b5c1c0ff0b7954ac8d81 Mon Sep 17 00:00:00 2001
From: Geert Uytterhoeven <geert+renesas@glider.be>
Date: Wed, 13 Dec 2017 20:05:13 +0100
Subject: [PATCH] spi: sh-msiof: Document hardware limitations related to chip
 selects

Guide users to maintain the proper balance between native and GPIO chip
selects.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
 Documentation/devicetree/bindings/spi/sh-msiof.txt | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/Documentation/devicetree/bindings/spi/sh-msiof.txt b/Documentation/devicetree/bindings/spi/sh-msiof.txt
index bc8c16a6cfc8..80710f0f0448 100644
--- a/Documentation/devicetree/bindings/spi/sh-msiof.txt
+++ b/Documentation/devicetree/bindings/spi/sh-msiof.txt
@@ -41,6 +41,16 @@ Optional properties:
 			   0: MSIOF_SYNC
 			   1: MSIOF_SS1
 			   2: MSIOF_SS2
+			 Hardware limitations related to chip selects:
+			   - Native chip selects are always deasserted in
+			     between transfers that are part of the same
+			     message.  Use cs-gpios to work around this.
+			   - All slaves using native chip selects must use the
+			     same spi-cs-high configuration.  Use cs-gpios to
+			     work around this.
+			   - When using GPIO chip selects, at least one native
+			     chip select must be left unused, as it will be
+			     driven anyway.
 - dmas                 : Must contain a list of two references to DMA
 			 specifiers, one for transmission, and one for
 			 reception.
-- 
2.15.1