[PATCH 0/2] spi: dw: Reintroduce optional 16 bit data register I/O

[PATCH 0/2] spi: dw: Reintroduce optional 16 bit data register I/O

[Michael van der Westhuizen]

The commit dd11444327ce ("spi: dw-spi: Convert 16bit accesses to 32bit
accesses") globally changed all register access in the dw_apb_ssi driver
to 32 bit access, which breaks data register (FIFO) access on picoXcell
platforms.

This series introduces a boolean to the core spi-dw driver to indicate
to the core that 16 bit data register access is appropriate, implements
the code that respects that flag and updates the dw-spi-mmio driver to
allow setting this boolean from the device tree.

A binding documentation fix is included in this series.

Prior to applying this change the following error presents on
a picoCell pc3x3 platform:
  spi_master spi32766: interrupt_transfer: fifo overrun/underrun
  m25p80 spi32766.0: error -5 reading 9f
  m25p80: probe of spi32766.0 failed with error -5

With this series applied:
  m25p80 spi32766.0: m25p40 (512 Kbytes)

Michael van der Westhuizen (2):
  dt: snps,dw-apb-ssi: Describe 16 bit data register usage limitations
  spi: dw: Allow interface drivers to limit data I/O to word sizes

 Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt |  3 +++
 drivers/spi/spi-dw-mmio.c                                 |  5 +++++
 drivers/spi/spi-dw.c                                      | 13 +++++++++++--
 drivers/spi/spi-dw.h                                      | 11 +++++++++++
 4 files changed, 30 insertions(+), 2 deletions(-)

-- 
2.1.4

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[PATCH 0/2] spi: dw: Reintroduce optional 16 bit data register I/O

[Michael van der Westhuizen]

The commit dd11444327ce ("spi: dw-spi: Convert 16bit accesses to 32bit
accesses") globally changed all register access in the dw_apb_ssi driver
to 32 bit access, which breaks data register (FIFO) access on picoXcell
platforms.

This series introduces a boolean to the core spi-dw driver to indicate
to the core that 16 bit data register access is appropriate, implements
the code that respects that flag and updates the dw-spi-mmio driver to
allow setting this boolean from the device tree.

A binding documentation fix is included in this series.

Prior to applying this change the following error presents on
a picoCell pc3x3 platform:
  spi_master spi32766: interrupt_transfer: fifo overrun/underrun
  m25p80 spi32766.0: error -5 reading 9f
  m25p80: probe of spi32766.0 failed with error -5

With this series applied:
  m25p80 spi32766.0: m25p40 (512 Kbytes)

Michael van der Westhuizen (2):
  dt: snps,dw-apb-ssi: Describe 16 bit data register usage limitations
  spi: dw: Allow interface drivers to limit data I/O to word sizes

 Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt |  3 +++
 drivers/spi/spi-dw-mmio.c                                 |  5 +++++
 drivers/spi/spi-dw.c                                      | 13 +++++++++++--
 drivers/spi/spi-dw.h                                      | 11 +++++++++++
 4 files changed, 30 insertions(+), 2 deletions(-)

-- 
2.1.4

[PATCH 2/2] dt: snps,dw-apb-ssi: Describe 16 bit data register usage limitations

[Michael van der Westhuizen]

This change documents a new property for the snps,dw-apb-ssi device,
allowing an implementer to interact with the SPI controller data
register in 16 bit mode only.  This supports a change that unbreaks
this driver on picoXcell platforms.

Signed-off-by: Michael van der Westhuizen <michael-XrNoQAPr3WXM9gW82pYGhQ@public.gmane.org>
---
 Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt b/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt
index bd99193..3b2a86f 100644
--- a/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt
+++ b/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt
@@ -10,6 +10,9 @@ Required properties:
 Optional properties:
 - cs-gpios : Specifies the gpio pis to be used for chipselects.
 - num-cs : The number of chipselects. If omitted, this will default to 4.
+- snps,data-io-16bit : A boolean property that, when present, causes
+  the driver to interact with the data register using 16 bit I/O instead
+  of the default 32 bit I/O.
 
 Child nodes as per the generic SPI binding.
 
-- 
2.1.4

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[PATCH 2/2] dt: snps, dw-apb-ssi: Describe 16 bit data register usage limitations

[Michael van der Westhuizen]

This change documents a new property for the snps,dw-apb-ssi device,
allowing an implementer to interact with the SPI controller data
register in 16 bit mode only.  This supports a change that unbreaks
this driver on picoXcell platforms.

Signed-off-by: Michael van der Westhuizen <michael@smart-africa.com>
---
 Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt b/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt
index bd99193..3b2a86f 100644
--- a/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt
+++ b/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt
@@ -10,6 +10,9 @@ Required properties:
 Optional properties:
 - cs-gpios : Specifies the gpio pis to be used for chipselects.
 - num-cs : The number of chipselects. If omitted, this will default to 4.
+- snps,data-io-16bit : A boolean property that, when present, causes
+  the driver to interact with the data register using 16 bit I/O instead
+  of the default 32 bit I/O.
 
 Child nodes as per the generic SPI binding.
 
-- 
2.1.4

[PATCH 1/2] spi: dw: Allow interface drivers to limit data I/O to word sizes

[Michael van der Westhuizen]

The commit dd11444327ce ("spi: dw-spi: Convert 16bit accesses to 32bit
accesses") changed all 16bit accesses in the DW_apb_ssi driver to 32bit.
This, unfortunately, breaks data register access on picoXcell, where the
DW IP needs data register accesses to be word accesses (all other
accesses appear to be OK).

This change introduces a new master variable to allow interface drivers
to specify that 16bit data transfer I/O is required.  This change also
introduces the ability to set this variable via device tree bindings in
the MMIO interface driver.

Before this change, on a picoXcell pc3x3:
 spi_master spi32766: interrupt_transfer: fifo overrun/underrun
 m25p80 spi32766.0: error -5 reading 9f
 m25p80: probe of spi32766.0 failed with error -5

After this change:
 m25p80 spi32766.0: m25p40 (512 Kbytes)

Signed-off-by: Michael van der Westhuizen <michael-XrNoQAPr3WXM9gW82pYGhQ@public.gmane.org>
---
 drivers/spi/spi-dw-mmio.c |  5 +++++
 drivers/spi/spi-dw.c      | 13 +++++++++++--
 drivers/spi/spi-dw.h      | 11 +++++++++++
 3 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c
index eb03e12..1397424 100644
--- a/drivers/spi/spi-dw-mmio.c
+++ b/drivers/spi/spi-dw-mmio.c
@@ -74,6 +74,11 @@ static int dw_spi_mmio_probe(struct platform_device *pdev)
 
 	dws->max_freq = clk_get_rate(dwsmmio->clk);
 
+	if (pdev->dev.of_node)
+		dws->data_io_16bit =
+			of_property_read_bool(pdev->dev.of_node,
+					      "snps,data-io-16bit");
+
 	num_cs = 4;
 
 	if (pdev->dev.of_node)
diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
index 8d67d03..862b001 100644
--- a/drivers/spi/spi-dw.c
+++ b/drivers/spi/spi-dw.c
@@ -194,7 +194,12 @@ static void dw_writer(struct dw_spi *dws)
 			else
 				txw = *(u16 *)(dws->tx);
 		}
-		dw_writel(dws, DW_SPI_DR, txw);
+
+		if (dws->data_io_16bit)
+			dw_writew(dws, DW_SPI_DR, txw);
+		else
+			dw_writel(dws, DW_SPI_DR, txw);
+
 		dws->tx += dws->n_bytes;
 	}
 }
@@ -205,7 +210,11 @@ static void dw_reader(struct dw_spi *dws)
 	u16 rxw;
 
 	while (max--) {
-		rxw = dw_readl(dws, DW_SPI_DR);
+		if (dws->data_io_16bit)
+			rxw = dw_readw(dws, DW_SPI_DR);
+		else
+			rxw = dw_readl(dws, DW_SPI_DR);
+
 		/* Care rx only if the transfer's original "rx" is not null */
 		if (dws->rx_end - dws->len) {
 			if (dws->n_bytes == 1)
diff --git a/drivers/spi/spi-dw.h b/drivers/spi/spi-dw.h
index 6c91391..ced276a 100644
--- a/drivers/spi/spi-dw.h
+++ b/drivers/spi/spi-dw.h
@@ -109,6 +109,7 @@ struct dw_spi {
 	u32			fifo_len;	/* depth of the FIFO buffer */
 	u32			max_freq;	/* max bus freq supported */
 
+	bool			data_io_16bit;	/* DR is only 16 bits wide */
 	u16			bus_num;
 	u16			num_cs;		/* supported slave numbers */
 
@@ -145,11 +146,21 @@ static inline u32 dw_readl(struct dw_spi *dws, u32 offset)
 	return __raw_readl(dws->regs + offset);
 }
 
+static inline u16 dw_readw(struct dw_spi *dws, u32 offset)
+{
+	return __raw_readw(dws->regs + offset);
+}
+
 static inline void dw_writel(struct dw_spi *dws, u32 offset, u32 val)
 {
 	__raw_writel(val, dws->regs + offset);
 }
 
+static inline void dw_writew(struct dw_spi *dws, u32 offset, u16 val)
+{
+	__raw_writew(val, dws->regs + offset);
+}
+
 static inline void spi_enable_chip(struct dw_spi *dws, int enable)
 {
 	dw_writel(dws, DW_SPI_SSIENR, (enable ? 1 : 0));
-- 
2.1.4

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[PATCH 1/2] spi: dw: Allow interface drivers to limit data I/O to word sizes

[Michael van der Westhuizen]

The commit dd11444327ce ("spi: dw-spi: Convert 16bit accesses to 32bit
accesses") changed all 16bit accesses in the DW_apb_ssi driver to 32bit.
This, unfortunately, breaks data register access on picoXcell, where the
DW IP needs data register accesses to be word accesses (all other
accesses appear to be OK).

This change introduces a new master variable to allow interface drivers
to specify that 16bit data transfer I/O is required.  This change also
introduces the ability to set this variable via device tree bindings in
the MMIO interface driver.

Before this change, on a picoXcell pc3x3:
 spi_master spi32766: interrupt_transfer: fifo overrun/underrun
 m25p80 spi32766.0: error -5 reading 9f
 m25p80: probe of spi32766.0 failed with error -5

After this change:
 m25p80 spi32766.0: m25p40 (512 Kbytes)

Signed-off-by: Michael van der Westhuizen <michael@smart-africa.com>
---
 drivers/spi/spi-dw-mmio.c |  5 +++++
 drivers/spi/spi-dw.c      | 13 +++++++++++--
 drivers/spi/spi-dw.h      | 11 +++++++++++
 3 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c
index eb03e12..1397424 100644
--- a/drivers/spi/spi-dw-mmio.c
+++ b/drivers/spi/spi-dw-mmio.c
@@ -74,6 +74,11 @@ static int dw_spi_mmio_probe(struct platform_device *pdev)
 
 	dws->max_freq = clk_get_rate(dwsmmio->clk);
 
+	if (pdev->dev.of_node)
+		dws->data_io_16bit =
+			of_property_read_bool(pdev->dev.of_node,
+					      "snps,data-io-16bit");
+
 	num_cs = 4;
 
 	if (pdev->dev.of_node)
diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
index 8d67d03..862b001 100644
--- a/drivers/spi/spi-dw.c
+++ b/drivers/spi/spi-dw.c
@@ -194,7 +194,12 @@ static void dw_writer(struct dw_spi *dws)
 			else
 				txw = *(u16 *)(dws->tx);
 		}
-		dw_writel(dws, DW_SPI_DR, txw);
+
+		if (dws->data_io_16bit)
+			dw_writew(dws, DW_SPI_DR, txw);
+		else
+			dw_writel(dws, DW_SPI_DR, txw);
+
 		dws->tx += dws->n_bytes;
 	}
 }
@@ -205,7 +210,11 @@ static void dw_reader(struct dw_spi *dws)
 	u16 rxw;
 
 	while (max--) {
-		rxw = dw_readl(dws, DW_SPI_DR);
+		if (dws->data_io_16bit)
+			rxw = dw_readw(dws, DW_SPI_DR);
+		else
+			rxw = dw_readl(dws, DW_SPI_DR);
+
 		/* Care rx only if the transfer's original "rx" is not null */
 		if (dws->rx_end - dws->len) {
 			if (dws->n_bytes == 1)
diff --git a/drivers/spi/spi-dw.h b/drivers/spi/spi-dw.h
index 6c91391..ced276a 100644
--- a/drivers/spi/spi-dw.h
+++ b/drivers/spi/spi-dw.h
@@ -109,6 +109,7 @@ struct dw_spi {
 	u32			fifo_len;	/* depth of the FIFO buffer */
 	u32			max_freq;	/* max bus freq supported */
 
+	bool			data_io_16bit;	/* DR is only 16 bits wide */
 	u16			bus_num;
 	u16			num_cs;		/* supported slave numbers */
 
@@ -145,11 +146,21 @@ static inline u32 dw_readl(struct dw_spi *dws, u32 offset)
 	return __raw_readl(dws->regs + offset);
 }
 
+static inline u16 dw_readw(struct dw_spi *dws, u32 offset)
+{
+	return __raw_readw(dws->regs + offset);
+}
+
 static inline void dw_writel(struct dw_spi *dws, u32 offset, u32 val)
 {
 	__raw_writel(val, dws->regs + offset);
 }
 
+static inline void dw_writew(struct dw_spi *dws, u32 offset, u16 val)
+{
+	__raw_writew(val, dws->regs + offset);
+}
+
 static inline void spi_enable_chip(struct dw_spi *dws, int enable)
 {
 	dw_writel(dws, DW_SPI_SSIENR, (enable ? 1 : 0));
-- 
2.1.4

Re: [PATCH 1/2] spi: dw: Allow interface drivers to limit data I/O to word sizes

[Andy Shevchenko]

On Fri, 2015-06-19 at 10:43 +0200, Michael van der Westhuizen wrote:
> The commit dd11444327ce ("spi: dw-spi: Convert 16bit accesses to 
> 32bit
> accesses") changed all 16bit accesses in the DW_apb_ssi driver to 
> 32bit.
> This, unfortunately, breaks data register access on picoXcell, where 
> the
> DW IP needs data register accesses to be word accesses (all other
> accesses appear to be OK).

Thanks for the patch. My comments below.

> 
> This change introduces a new master variable to allow interface 
> drivers
> to specify that 16bit data transfer I/O is required.  This change 
> also
> introduces the ability to set this variable via device tree bindings 
> in
> the MMIO interface driver.
> 
> Before this change, on a picoXcell pc3x3:
>  spi_master spi32766: interrupt_transfer: fifo overrun/underrun
>  m25p80 spi32766.0: error -5 reading 9f
>  m25p80: probe of spi32766.0 failed with error -5
> 
> After this change:
>  m25p80 spi32766.0: m25p40 (512 Kbytes)
> 

Please, add Fixes: tag as well.

> Signed-off-by: Michael van der Westhuizen <michael-XrNoQAPr3WXM9gW82pYGhQ@public.gmane.org>
> ---
>  drivers/spi/spi-dw-mmio.c |  5 +++++
>  drivers/spi/spi-dw.c      | 13 +++++++++++--
>  drivers/spi/spi-dw.h      | 11 +++++++++++
>  3 files changed, 27 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c
> index eb03e12..1397424 100644
> --- a/drivers/spi/spi-dw-mmio.c
> +++ b/drivers/spi/spi-dw-mmio.c
> @@ -74,6 +74,11 @@ static int dw_spi_mmio_probe(struct 
> platform_device *pdev)
>  
>  	dws->max_freq = clk_get_rate(dwsmmio->clk);
>  
> +	if (pdev->dev.of_node)
> +		dws->data_io_16bit =

I don't like "flexibility" in the  DeviceTree data base and thus I
would prefer to see what we already have in naming there, i.e.
reg-io-width = 2 or 4.

> +			of_property_read_bool(pdev->dev.of_node,
> +					      "snps,data-io-16bit");
> +
>  	num_cs = 4;
>  
>  	if (pdev->dev.of_node)
> diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
> index 8d67d03..862b001 100644
> --- a/drivers/spi/spi-dw.c
> +++ b/drivers/spi/spi-dw.c
> @@ -194,7 +194,12 @@ static void dw_writer(struct dw_spi *dws)
>  			else
>  				txw = *(u16 *)(dws->tx);
>  		}
> -		dw_writel(dws, DW_SPI_DR, txw);
> +
> +		if (dws->data_io_16bit)
> +			dw_writew(dws, DW_SPI_DR, txw);
> +		else
> +			dw_writel(dws, DW_SPI_DR, txw);
> +
>  		dws->tx += dws->n_bytes;
>  	}
>  }
> @@ -205,7 +210,11 @@ static void dw_reader(struct dw_spi *dws)
>  	u16 rxw;
>  
>  	while (max--) {
> -		rxw = dw_readl(dws, DW_SPI_DR);
> +		if (dws->data_io_16bit)
> +			rxw = dw_readw(dws, DW_SPI_DR);
> +		else
> +			rxw = dw_readl(dws, DW_SPI_DR);
> +
>  		/* Care rx only if the transfer's original "rx" is 
> not null */
>  		if (dws->rx_end - dws->len) {
>  			if (dws->n_bytes == 1)
> diff --git a/drivers/spi/spi-dw.h b/drivers/spi/spi-dw.h
> index 6c91391..ced276a 100644
> --- a/drivers/spi/spi-dw.h
> +++ b/drivers/spi/spi-dw.h
> @@ -109,6 +109,7 @@ struct dw_spi {
>  	u32			fifo_len;	/* depth of the FIFO 
> buffer */
>  	u32			max_freq;	/* max bus freq 
> supported */
>  
> +	bool			data_io_16bit;	/* DR is only 16 
> bits wide */
>  	u16			bus_num;
>  	u16			num_cs;		/* supported 
> slave numbers */
>  
> @@ -145,11 +146,21 @@ static inline u32 dw_readl(struct dw_spi *dws, 
> u32 offset)
>  	return __raw_readl(dws->regs + offset);
>  }
>  
> +static inline u16 dw_readw(struct dw_spi *dws, u32 offset)
> +{
> +	return __raw_readw(dws->regs + offset);
> +}
> +
>  static inline void dw_writel(struct dw_spi *dws, u32 offset, u32 
> val)
>  {
>  	__raw_writel(val, dws->regs + offset);
>  }
>  
> +static inline void dw_writew(struct dw_spi *dws, u32 offset, u16 
> val)
> +{
> +	__raw_writew(val, dws->regs + offset);
> +}
> +
>  static inline void spi_enable_chip(struct dw_spi *dws, int enable)
>  {
>  	dw_writel(dws, DW_SPI_SSIENR, (enable ? 1 : 0));

Regarding to above comment what about something like

static inline u32 dw_read_reg(dws, offset)
{
 switch (reg_io_width)
 case 2:
  return dw_readw();
 case 4:
 default:
  return dw_readl();
}


-- 
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Intel Finland Oy
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[PATCH 1/2] spi: dw: Allow interface drivers to limit data I/O to word sizes

[Andy Shevchenko]

On Fri, 2015-06-19 at 10:43 +0200, Michael van der Westhuizen wrote:
> The commit dd11444327ce ("spi: dw-spi: Convert 16bit accesses to 
> 32bit
> accesses") changed all 16bit accesses in the DW_apb_ssi driver to 
> 32bit.
> This, unfortunately, breaks data register access on picoXcell, where 
> the
> DW IP needs data register accesses to be word accesses (all other
> accesses appear to be OK).

Thanks for the patch. My comments below.

> 
> This change introduces a new master variable to allow interface 
> drivers
> to specify that 16bit data transfer I/O is required.  This change 
> also
> introduces the ability to set this variable via device tree bindings 
> in
> the MMIO interface driver.
> 
> Before this change, on a picoXcell pc3x3:
>  spi_master spi32766: interrupt_transfer: fifo overrun/underrun
>  m25p80 spi32766.0: error -5 reading 9f
>  m25p80: probe of spi32766.0 failed with error -5
> 
> After this change:
>  m25p80 spi32766.0: m25p40 (512 Kbytes)
> 

Please, add Fixes: tag as well.

> Signed-off-by: Michael van der Westhuizen <michael@smart-africa.com>
> ---
>  drivers/spi/spi-dw-mmio.c |  5 +++++
>  drivers/spi/spi-dw.c      | 13 +++++++++++--
>  drivers/spi/spi-dw.h      | 11 +++++++++++
>  3 files changed, 27 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c
> index eb03e12..1397424 100644
> --- a/drivers/spi/spi-dw-mmio.c
> +++ b/drivers/spi/spi-dw-mmio.c
> @@ -74,6 +74,11 @@ static int dw_spi_mmio_probe(struct 
> platform_device *pdev)
>  
>  	dws->max_freq = clk_get_rate(dwsmmio->clk);
>  
> +	if (pdev->dev.of_node)
> +		dws->data_io_16bit =

I don't like "flexibility" in the  DeviceTree data base and thus I
would prefer to see what we already have in naming there, i.e.
reg-io-width = 2 or 4.

> +			of_property_read_bool(pdev->dev.of_node,
> +					      "snps,data-io-16bit");
> +
>  	num_cs = 4;
>  
>  	if (pdev->dev.of_node)
> diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
> index 8d67d03..862b001 100644
> --- a/drivers/spi/spi-dw.c
> +++ b/drivers/spi/spi-dw.c
> @@ -194,7 +194,12 @@ static void dw_writer(struct dw_spi *dws)
>  			else
>  				txw = *(u16 *)(dws->tx);
>  		}
> -		dw_writel(dws, DW_SPI_DR, txw);
> +
> +		if (dws->data_io_16bit)
> +			dw_writew(dws, DW_SPI_DR, txw);
> +		else
> +			dw_writel(dws, DW_SPI_DR, txw);
> +
>  		dws->tx += dws->n_bytes;
>  	}
>  }
> @@ -205,7 +210,11 @@ static void dw_reader(struct dw_spi *dws)
>  	u16 rxw;
>  
>  	while (max--) {
> -		rxw = dw_readl(dws, DW_SPI_DR);
> +		if (dws->data_io_16bit)
> +			rxw = dw_readw(dws, DW_SPI_DR);
> +		else
> +			rxw = dw_readl(dws, DW_SPI_DR);
> +
>  		/* Care rx only if the transfer's original "rx" is 
> not null */
>  		if (dws->rx_end - dws->len) {
>  			if (dws->n_bytes == 1)
> diff --git a/drivers/spi/spi-dw.h b/drivers/spi/spi-dw.h
> index 6c91391..ced276a 100644
> --- a/drivers/spi/spi-dw.h
> +++ b/drivers/spi/spi-dw.h
> @@ -109,6 +109,7 @@ struct dw_spi {
>  	u32			fifo_len;	/* depth of the FIFO 
> buffer */
>  	u32			max_freq;	/* max bus freq 
> supported */
>  
> +	bool			data_io_16bit;	/* DR is only 16 
> bits wide */
>  	u16			bus_num;
>  	u16			num_cs;		/* supported 
> slave numbers */
>  
> @@ -145,11 +146,21 @@ static inline u32 dw_readl(struct dw_spi *dws, 
> u32 offset)
>  	return __raw_readl(dws->regs + offset);
>  }
>  
> +static inline u16 dw_readw(struct dw_spi *dws, u32 offset)
> +{
> +	return __raw_readw(dws->regs + offset);
> +}
> +
>  static inline void dw_writel(struct dw_spi *dws, u32 offset, u32 
> val)
>  {
>  	__raw_writel(val, dws->regs + offset);
>  }
>  
> +static inline void dw_writew(struct dw_spi *dws, u32 offset, u16 
> val)
> +{
> +	__raw_writew(val, dws->regs + offset);
> +}
> +
>  static inline void spi_enable_chip(struct dw_spi *dws, int enable)
>  {
>  	dw_writel(dws, DW_SPI_SSIENR, (enable ? 1 : 0));

Regarding to above comment what about something like

static inline u32 dw_read_reg(dws, offset)
{
 switch (reg_io_width)
 case 2:
  return dw_readw();
 case 4:
 default:
  return dw_readl();
}


-- 
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy

Re: [PATCH 1/2] spi: dw: Allow interface drivers to limit data I/O to word sizes

[Michael van der Westhuizen]

[-- Attachment #1: Type: text/plain, Size: 3150 bytes --]


> On 24 Jun 2015, at 1:57 PM, Andy Shevchenko <andriy.shevchenko@linux.intel.com> wrote:
> 
> On Fri, 2015-06-19 at 10:43 +0200, Michael van der Westhuizen wrote:
>> The commit dd11444327ce ("spi: dw-spi: Convert 16bit accesses to 
>> 32bit
>> accesses") changed all 16bit accesses in the DW_apb_ssi driver to 
>> 32bit.
>> This, unfortunately, breaks data register access on picoXcell, where 
>> the
>> DW IP needs data register accesses to be word accesses (all other
>> accesses appear to be OK).
> 
> Thanks for the patch. My comments below.
> 
>> 
>> This change introduces a new master variable to allow interface 
>> drivers
>> to specify that 16bit data transfer I/O is required.  This change 
>> also
>> introduces the ability to set this variable via device tree bindings 
>> in
>> the MMIO interface driver.
>> 
>> Before this change, on a picoXcell pc3x3:
>> spi_master spi32766: interrupt_transfer: fifo overrun/underrun
>> m25p80 spi32766.0: error -5 reading 9f
>> m25p80: probe of spi32766.0 failed with error -5
>> 
>> After this change:
>> m25p80 spi32766.0: m25p40 (512 Kbytes)
>> 
> 
> Please, add Fixes: tag as well.

OK.

> 
>> Signed-off-by: Michael van der Westhuizen <michael@smart-africa.com>
>> ---
>> drivers/spi/spi-dw-mmio.c |  5 +++++
>> drivers/spi/spi-dw.c      | 13 +++++++++++--
>> drivers/spi/spi-dw.h      | 11 +++++++++++
>> 3 files changed, 27 insertions(+), 2 deletions(-)
>> 
>> diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c
>> index eb03e12..1397424 100644
>> --- a/drivers/spi/spi-dw-mmio.c
>> +++ b/drivers/spi/spi-dw-mmio.c
>> @@ -74,6 +74,11 @@ static int dw_spi_mmio_probe(struct 
>> platform_device *pdev)
>> 
>> 	dws->max_freq = clk_get_rate(dwsmmio->clk);
>> 
>> +	if (pdev->dev.of_node)
>> +		dws->data_io_16bit =
> 
> I don't like "flexibility" in the  DeviceTree data base and thus I
> would prefer to see what we already have in naming there, i.e.
> reg-io-width = 2 or 4.

Will update.

<snip>

>> @@ -145,11 +146,21 @@ static inline u32 dw_readl(struct dw_spi *dws, 
>> u32 offset)
>> 	return __raw_readl(dws->regs + offset);
>> }
>> 
>> +static inline u16 dw_readw(struct dw_spi *dws, u32 offset)
>> +{
>> +	return __raw_readw(dws->regs + offset);
>> +}
>> +
>> static inline void dw_writel(struct dw_spi *dws, u32 offset, u32 
>> val)
>> {
>> 	__raw_writel(val, dws->regs + offset);
>> }
>> 
>> +static inline void dw_writew(struct dw_spi *dws, u32 offset, u16 
>> val)
>> +{
>> +	__raw_writew(val, dws->regs + offset);
>> +}
>> +
>> static inline void spi_enable_chip(struct dw_spi *dws, int enable)
>> {
>> 	dw_writel(dws, DW_SPI_SSIENR, (enable ? 1 : 0));
> 
> Regarding to above comment what about something like
> 
> static inline u32 dw_read_reg(dws, offset)
> {
> switch (reg_io_width)
> case 2:
>  return dw_readw();
> case 4:
> default:
>  return dw_readl();
> }

Yes, that would be better.  Note that this will only be used for data
register access, as the other registers seem fine with 32 bit access.

I’ll update the series and resend.

Michael


[-- Attachment #2: Type: text/html, Size: 20765 bytes --]

[PATCH v2 0/2] spi: dw: Reintroduce optional 16 bit data register I/O

[Michael van der Westhuizen]

The commit dd11444327ce ("spi: dw-spi: Convert 16bit accesses to 32bit
accesses") globally changed all register access in the dw_apb_ssi driver
to 32 bit access, which breaks data register (FIFO) access on picoXcell
platforms.

This series introduces a boolean to the core spi-dw driver to indicate
to the core that 16 bit data register access is appropriate, implements
the code that respects that flag and updates the dw-spi-mmio driver to
allow setting this boolean from the device tree.

A binding documentation fix is included in this series.

Prior to applying this change the following error presents on
a picoCell pc3x3 platform:
  spi_master spi32766: interrupt_transfer: fifo overrun/underrun
  m25p80 spi32766.0: error -5 reading 9f
  m25p80: probe of spi32766.0 failed with error -5

With this series applied:
  m25p80 spi32766.0: m25p40 (512 Kbytes)

Changes in v2:
  - Incorporate review feedback from Andy Shevchenko, reworking the
    bindings to reflect common practice and adjusting the driver
    to suit.
  - Add a wrapper inline function for accessing the data register
    using the configured with.

Michael van der Westhuizen (2):
  dt: snps,dw-apb-ssi: Document new I/O data register width property
  spi: dw: Allow interface drivers to limit data I/O to word sizes

 drivers/spi/spi-dw-mmio.c |  4 ++++
 drivers/spi/spi-dw.c      |  4 ++--
 drivers/spi/spi-dw.h      | 35 +++++++++++++++++++++++++++++++++++
 3 files changed, 41 insertions(+), 2 deletions(-)

-- 
2.1.4

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[PATCH v2 0/2] spi: dw: Reintroduce optional 16 bit data register I/O

[Michael van der Westhuizen]

The commit dd11444327ce ("spi: dw-spi: Convert 16bit accesses to 32bit
accesses") globally changed all register access in the dw_apb_ssi driver
to 32 bit access, which breaks data register (FIFO) access on picoXcell
platforms.

This series introduces a boolean to the core spi-dw driver to indicate
to the core that 16 bit data register access is appropriate, implements
the code that respects that flag and updates the dw-spi-mmio driver to
allow setting this boolean from the device tree.

A binding documentation fix is included in this series.

Prior to applying this change the following error presents on
a picoCell pc3x3 platform:
  spi_master spi32766: interrupt_transfer: fifo overrun/underrun
  m25p80 spi32766.0: error -5 reading 9f
  m25p80: probe of spi32766.0 failed with error -5

With this series applied:
  m25p80 spi32766.0: m25p40 (512 Kbytes)

Changes in v2:
  - Incorporate review feedback from Andy Shevchenko, reworking the
    bindings to reflect common practice and adjusting the driver
    to suit.
  - Add a wrapper inline function for accessing the data register
    using the configured with.

Michael van der Westhuizen (2):
  dt: snps,dw-apb-ssi: Document new I/O data register width property
  spi: dw: Allow interface drivers to limit data I/O to word sizes

 drivers/spi/spi-dw-mmio.c |  4 ++++
 drivers/spi/spi-dw.c      |  4 ++--
 drivers/spi/spi-dw.h      | 35 +++++++++++++++++++++++++++++++++++
 3 files changed, 41 insertions(+), 2 deletions(-)

-- 
2.1.4

[PATCH v2 1/2] dt: snps,dw-apb-ssi: Document new I/O data register width property

[Michael van der Westhuizen]

This change documents a new property for the snps,dw-apb-ssi device,
allowing an implementer to specify either four byte or two bytes
access to the SPI controller data register.

This supports a change that unbreaks this driver on picoXcell
platforms.

Signed-off-by: Michael van der Westhuizen <michael-XrNoQAPr3WXM9gW82pYGhQ@public.gmane.org>
---

Changes in v2:
  - Incorporate review feedback from Andy Shevchenko, reworking the
    bindings to reflect common practice.

 Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt b/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt
index bd99193..b4f1086 100644
--- a/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt
+++ b/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt
@@ -10,6 +10,8 @@ Required properties:
 Optional properties:
 - cs-gpios : Specifies the gpio pis to be used for chipselects.
 - num-cs : The number of chipselects. If omitted, this will default to 4.
+- snps,reg-io-width : The I/O register width (in bytes) implemented by
+  this device.  Supported values are 2 or 4 (the default).
 
 Child nodes as per the generic SPI binding.
 
-- 
2.1.4

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[PATCH v2 1/2] dt: snps, dw-apb-ssi: Document new I/O data register width property

[Michael van der Westhuizen]

This change documents a new property for the snps,dw-apb-ssi device,
allowing an implementer to specify either four byte or two bytes
access to the SPI controller data register.

This supports a change that unbreaks this driver on picoXcell
platforms.

Signed-off-by: Michael van der Westhuizen <michael@smart-africa.com>
---

Changes in v2:
  - Incorporate review feedback from Andy Shevchenko, reworking the
    bindings to reflect common practice.

 Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt b/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt
index bd99193..b4f1086 100644
--- a/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt
+++ b/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt
@@ -10,6 +10,8 @@ Required properties:
 Optional properties:
 - cs-gpios : Specifies the gpio pis to be used for chipselects.
 - num-cs : The number of chipselects. If omitted, this will default to 4.
+- snps,reg-io-width : The I/O register width (in bytes) implemented by
+  this device.  Supported values are 2 or 4 (the default).
 
 Child nodes as per the generic SPI binding.
 
-- 
2.1.4

[PATCH v2 2/2] spi: dw: Allow interface drivers to limit data I/O to word sizes

[Michael van der Westhuizen]

The commit dd11444327ce ("spi: dw-spi: Convert 16bit accesses to 32bit
accesses") changed all 16bit accesses in the DW_apb_ssi driver to 32bit.
This, unfortunately, breaks data register access on picoXcell, where the
DW IP needs data register accesses to be word accesses (all other
accesses appear to be OK).

This change introduces a new master variable to allow interface drivers
to specify that 16bit data transfer I/O is required.  This change also
introduces the ability to set this variable via device tree bindings in
the MMIO interface driver.

Before this change, on a picoXcell pc3x3:
 spi_master spi32766: interrupt_transfer: fifo overrun/underrun
 m25p80 spi32766.0: error -5 reading 9f
 m25p80: probe of spi32766.0 failed with error -5

After this change:
 m25p80 spi32766.0: m25p40 (512 Kbytes)

Fixes: dd11444327ce ("spi: dw-spi: Convert 16bit accesses to 32bit accesses")
Signed-off-by: Michael van der Westhuizen <michael-XrNoQAPr3WXM9gW82pYGhQ@public.gmane.org>
---

Changes in v2:
  - Incorporate review feedback from Andy Shevchenko
    - Rework the DT bindings to accept an I/O register width as a
      number of bytes rather than using a boolean spefifying the
      width preference to be 16 bits.
    - Add data register access wrapper functions and use them when
      reading and writing the data register.

 drivers/spi/spi-dw-mmio.c |  4 ++++
 drivers/spi/spi-dw.c      |  4 ++--
 drivers/spi/spi-dw.h      | 35 +++++++++++++++++++++++++++++++++++
 3 files changed, 41 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c
index eb03e12..e76bf72 100644
--- a/drivers/spi/spi-dw-mmio.c
+++ b/drivers/spi/spi-dw-mmio.c
@@ -74,6 +74,10 @@ static int dw_spi_mmio_probe(struct platform_device *pdev)
 
 	dws->max_freq = clk_get_rate(dwsmmio->clk);
 
+	if (pdev->dev.of_node)
+		of_property_read_u32(pdev->dev.of_node, "snps,reg-io-width",
+				     &dws->reg_io_width);
+
 	num_cs = 4;
 
 	if (pdev->dev.of_node)
diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
index 8d67d03..4fbfcdc 100644
--- a/drivers/spi/spi-dw.c
+++ b/drivers/spi/spi-dw.c
@@ -194,7 +194,7 @@ static void dw_writer(struct dw_spi *dws)
 			else
 				txw = *(u16 *)(dws->tx);
 		}
-		dw_writel(dws, DW_SPI_DR, txw);
+		dw_write_io_reg(dws, DW_SPI_DR, txw);
 		dws->tx += dws->n_bytes;
 	}
 }
@@ -205,7 +205,7 @@ static void dw_reader(struct dw_spi *dws)
 	u16 rxw;
 
 	while (max--) {
-		rxw = dw_readl(dws, DW_SPI_DR);
+		rxw = dw_read_io_reg(dws, DW_SPI_DR);
 		/* Care rx only if the transfer's original "rx" is not null */
 		if (dws->rx_end - dws->len) {
 			if (dws->n_bytes == 1)
diff --git a/drivers/spi/spi-dw.h b/drivers/spi/spi-dw.h
index 6c91391..b75ed32 100644
--- a/drivers/spi/spi-dw.h
+++ b/drivers/spi/spi-dw.h
@@ -109,6 +109,7 @@ struct dw_spi {
 	u32			fifo_len;	/* depth of the FIFO buffer */
 	u32			max_freq;	/* max bus freq supported */
 
+	u32			reg_io_width;	/* DR I/O width in bytes */
 	u16			bus_num;
 	u16			num_cs;		/* supported slave numbers */
 
@@ -145,11 +146,45 @@ static inline u32 dw_readl(struct dw_spi *dws, u32 offset)
 	return __raw_readl(dws->regs + offset);
 }
 
+static inline u16 dw_readw(struct dw_spi *dws, u32 offset)
+{
+	return __raw_readw(dws->regs + offset);
+}
+
 static inline void dw_writel(struct dw_spi *dws, u32 offset, u32 val)
 {
 	__raw_writel(val, dws->regs + offset);
 }
 
+static inline void dw_writew(struct dw_spi *dws, u32 offset, u16 val)
+{
+	__raw_writew(val, dws->regs + offset);
+}
+
+static inline u32 dw_read_io_reg(struct dw_spi *dws, u32 offset)
+{
+	switch (dws->reg_io_width) {
+	case 2:
+		return dw_readw(dws, offset);
+	case 4:
+	default:
+		return dw_readl(dws, offset);
+	}
+}
+
+static inline void dw_write_io_reg(struct dw_spi *dws, u32 offset, u32 val)
+{
+	switch (dws->reg_io_width) {
+	case 2:
+		dw_writew(dws, offset, val);
+		break;
+	case 4:
+	default:
+		dw_writel(dws, offset, val);
+		break;
+	}
+}
+
 static inline void spi_enable_chip(struct dw_spi *dws, int enable)
 {
 	dw_writel(dws, DW_SPI_SSIENR, (enable ? 1 : 0));
-- 
2.1.4

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[PATCH v2 2/2] spi: dw: Allow interface drivers to limit data I/O to word sizes

[Michael van der Westhuizen]

The commit dd11444327ce ("spi: dw-spi: Convert 16bit accesses to 32bit
accesses") changed all 16bit accesses in the DW_apb_ssi driver to 32bit.
This, unfortunately, breaks data register access on picoXcell, where the
DW IP needs data register accesses to be word accesses (all other
accesses appear to be OK).

This change introduces a new master variable to allow interface drivers
to specify that 16bit data transfer I/O is required.  This change also
introduces the ability to set this variable via device tree bindings in
the MMIO interface driver.

Before this change, on a picoXcell pc3x3:
 spi_master spi32766: interrupt_transfer: fifo overrun/underrun
 m25p80 spi32766.0: error -5 reading 9f
 m25p80: probe of spi32766.0 failed with error -5

After this change:
 m25p80 spi32766.0: m25p40 (512 Kbytes)

Fixes: dd11444327ce ("spi: dw-spi: Convert 16bit accesses to 32bit accesses")
Signed-off-by: Michael van der Westhuizen <michael@smart-africa.com>
---

Changes in v2:
  - Incorporate review feedback from Andy Shevchenko
    - Rework the DT bindings to accept an I/O register width as a
      number of bytes rather than using a boolean spefifying the
      width preference to be 16 bits.
    - Add data register access wrapper functions and use them when
      reading and writing the data register.

 drivers/spi/spi-dw-mmio.c |  4 ++++
 drivers/spi/spi-dw.c      |  4 ++--
 drivers/spi/spi-dw.h      | 35 +++++++++++++++++++++++++++++++++++
 3 files changed, 41 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c
index eb03e12..e76bf72 100644
--- a/drivers/spi/spi-dw-mmio.c
+++ b/drivers/spi/spi-dw-mmio.c
@@ -74,6 +74,10 @@ static int dw_spi_mmio_probe(struct platform_device *pdev)
 
 	dws->max_freq = clk_get_rate(dwsmmio->clk);
 
+	if (pdev->dev.of_node)
+		of_property_read_u32(pdev->dev.of_node, "snps,reg-io-width",
+				     &dws->reg_io_width);
+
 	num_cs = 4;
 
 	if (pdev->dev.of_node)
diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
index 8d67d03..4fbfcdc 100644
--- a/drivers/spi/spi-dw.c
+++ b/drivers/spi/spi-dw.c
@@ -194,7 +194,7 @@ static void dw_writer(struct dw_spi *dws)
 			else
 				txw = *(u16 *)(dws->tx);
 		}
-		dw_writel(dws, DW_SPI_DR, txw);
+		dw_write_io_reg(dws, DW_SPI_DR, txw);
 		dws->tx += dws->n_bytes;
 	}
 }
@@ -205,7 +205,7 @@ static void dw_reader(struct dw_spi *dws)
 	u16 rxw;
 
 	while (max--) {
-		rxw = dw_readl(dws, DW_SPI_DR);
+		rxw = dw_read_io_reg(dws, DW_SPI_DR);
 		/* Care rx only if the transfer's original "rx" is not null */
 		if (dws->rx_end - dws->len) {
 			if (dws->n_bytes == 1)
diff --git a/drivers/spi/spi-dw.h b/drivers/spi/spi-dw.h
index 6c91391..b75ed32 100644
--- a/drivers/spi/spi-dw.h
+++ b/drivers/spi/spi-dw.h
@@ -109,6 +109,7 @@ struct dw_spi {
 	u32			fifo_len;	/* depth of the FIFO buffer */
 	u32			max_freq;	/* max bus freq supported */
 
+	u32			reg_io_width;	/* DR I/O width in bytes */
 	u16			bus_num;
 	u16			num_cs;		/* supported slave numbers */
 
@@ -145,11 +146,45 @@ static inline u32 dw_readl(struct dw_spi *dws, u32 offset)
 	return __raw_readl(dws->regs + offset);
 }
 
+static inline u16 dw_readw(struct dw_spi *dws, u32 offset)
+{
+	return __raw_readw(dws->regs + offset);
+}
+
 static inline void dw_writel(struct dw_spi *dws, u32 offset, u32 val)
 {
 	__raw_writel(val, dws->regs + offset);
 }
 
+static inline void dw_writew(struct dw_spi *dws, u32 offset, u16 val)
+{
+	__raw_writew(val, dws->regs + offset);
+}
+
+static inline u32 dw_read_io_reg(struct dw_spi *dws, u32 offset)
+{
+	switch (dws->reg_io_width) {
+	case 2:
+		return dw_readw(dws, offset);
+	case 4:
+	default:
+		return dw_readl(dws, offset);
+	}
+}
+
+static inline void dw_write_io_reg(struct dw_spi *dws, u32 offset, u32 val)
+{
+	switch (dws->reg_io_width) {
+	case 2:
+		dw_writew(dws, offset, val);
+		break;
+	case 4:
+	default:
+		dw_writel(dws, offset, val);
+		break;
+	}
+}
+
 static inline void spi_enable_chip(struct dw_spi *dws, int enable)
 {
 	dw_writel(dws, DW_SPI_SSIENR, (enable ? 1 : 0));
-- 
2.1.4

Re: [PATCH v2 2/2] spi: dw: Allow interface drivers to limit data I/O to word sizes

[Andy Shevchenko]

On Wed, 2015-06-24 at 18:34 +0200, Michael van der Westhuizen wrote:
> The commit dd11444327ce ("spi: dw-spi: Convert 16bit accesses to 
> 32bit
> accesses") changed all 16bit accesses in the DW_apb_ssi driver to 
> 32bit.
> This, unfortunately, breaks data register access on picoXcell, where 
> the
> DW IP needs data register accesses to be word accesses (all other
> accesses appear to be OK).
> 
> This change introduces a new master variable to allow interface 
> drivers
> to specify that 16bit data transfer I/O is required.  This change 
> also
> introduces the ability to set this variable via device tree bindings 
> in
> the MMIO interface driver.
> 
> Before this change, on a picoXcell pc3x3:
>  spi_master spi32766: interrupt_transfer: fifo overrun/underrun
>  m25p80 spi32766.0: error -5 reading 9f
>  m25p80: probe of spi32766.0 failed with error -5
> 
> After this change:
>  m25p80 spi32766.0: m25p40 (512 Kbytes)

Reviewed-by: Andy Shevchenko <andriy.shevchenko-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>

> 
> Fixes: dd11444327ce ("spi: dw-spi: Convert 16bit accesses to 32bit 
> accesses")
> Signed-off-by: Michael van der Westhuizen <michael-XrNoQAPr3WXM9gW82pYGhQ@public.gmane.org>
> ---
> 
> Changes in v2:
>   - Incorporate review feedback from Andy Shevchenko
>     - Rework the DT bindings to accept an I/O register width as a
>       number of bytes rather than using a boolean spefifying the
>       width preference to be 16 bits.
>     - Add data register access wrapper functions and use them when
>       reading and writing the data register.
> 
>  drivers/spi/spi-dw-mmio.c |  4 ++++
>  drivers/spi/spi-dw.c      |  4 ++--
>  drivers/spi/spi-dw.h      | 35 +++++++++++++++++++++++++++++++++++
>  3 files changed, 41 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c
> index eb03e12..e76bf72 100644
> --- a/drivers/spi/spi-dw-mmio.c
> +++ b/drivers/spi/spi-dw-mmio.c
> @@ -74,6 +74,10 @@ static int dw_spi_mmio_probe(struct 
> platform_device *pdev)
>  
>  	dws->max_freq = clk_get_rate(dwsmmio->clk);
>  
> +	if (pdev->dev.of_node)
> +		of_property_read_u32(pdev->dev.of_node, "snps,reg-io
> -width",
> +				     &dws->reg_io_width);
> +
>  	num_cs = 4;
>  
>  	if (pdev->dev.of_node)
> diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
> index 8d67d03..4fbfcdc 100644
> --- a/drivers/spi/spi-dw.c
> +++ b/drivers/spi/spi-dw.c
> @@ -194,7 +194,7 @@ static void dw_writer(struct dw_spi *dws)
>  			else
>  				txw = *(u16 *)(dws->tx);
>  		}
> -		dw_writel(dws, DW_SPI_DR, txw);
> +		dw_write_io_reg(dws, DW_SPI_DR, txw);
>  		dws->tx += dws->n_bytes;
>  	}
>  }
> @@ -205,7 +205,7 @@ static void dw_reader(struct dw_spi *dws)
>  	u16 rxw;
>  
>  	while (max--) {
> -		rxw = dw_readl(dws, DW_SPI_DR);
> +		rxw = dw_read_io_reg(dws, DW_SPI_DR);
>  		/* Care rx only if the transfer's original "rx" is 
> not null */
>  		if (dws->rx_end - dws->len) {
>  			if (dws->n_bytes == 1)
> diff --git a/drivers/spi/spi-dw.h b/drivers/spi/spi-dw.h
> index 6c91391..b75ed32 100644
> --- a/drivers/spi/spi-dw.h
> +++ b/drivers/spi/spi-dw.h
> @@ -109,6 +109,7 @@ struct dw_spi {
>  	u32			fifo_len;	/* depth of the FIFO 
> buffer */
>  	u32			max_freq;	/* max bus freq 
> supported */
>  
> +	u32			reg_io_width;	/* DR I/O width in 
> bytes */
>  	u16			bus_num;
>  	u16			num_cs;		/* supported 
> slave numbers */
>  
> @@ -145,11 +146,45 @@ static inline u32 dw_readl(struct dw_spi *dws, 
> u32 offset)
>  	return __raw_readl(dws->regs + offset);
>  }
>  
> +static inline u16 dw_readw(struct dw_spi *dws, u32 offset)
> +{
> +	return __raw_readw(dws->regs + offset);
> +}
> +
>  static inline void dw_writel(struct dw_spi *dws, u32 offset, u32 
> val)
>  {
>  	__raw_writel(val, dws->regs + offset);
>  }
>  
> +static inline void dw_writew(struct dw_spi *dws, u32 offset, u16 
> val)
> +{
> +	__raw_writew(val, dws->regs + offset);
> +}
> +
> +static inline u32 dw_read_io_reg(struct dw_spi *dws, u32 offset)
> +{
> +	switch (dws->reg_io_width) {
> +	case 2:
> +		return dw_readw(dws, offset);
> +	case 4:
> +	default:
> +		return dw_readl(dws, offset);
> +	}
> +}
> +
> +static inline void dw_write_io_reg(struct dw_spi *dws, u32 offset, 
> u32 val)
> +{
> +	switch (dws->reg_io_width) {
> +	case 2:
> +		dw_writew(dws, offset, val);
> +		break;
> +	case 4:
> +	default:
> +		dw_writel(dws, offset, val);
> +		break;
> +	}
> +}
> +
>  static inline void spi_enable_chip(struct dw_spi *dws, int enable)
>  {
>  	dw_writel(dws, DW_SPI_SSIENR, (enable ? 1 : 0));

-- 
Andy Shevchenko <andriy.shevchenko-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
Intel Finland Oy
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[PATCH v2 2/2] spi: dw: Allow interface drivers to limit data I/O to word sizes

[Andy Shevchenko]

On Wed, 2015-06-24 at 18:34 +0200, Michael van der Westhuizen wrote:
> The commit dd11444327ce ("spi: dw-spi: Convert 16bit accesses to 
> 32bit
> accesses") changed all 16bit accesses in the DW_apb_ssi driver to 
> 32bit.
> This, unfortunately, breaks data register access on picoXcell, where 
> the
> DW IP needs data register accesses to be word accesses (all other
> accesses appear to be OK).
> 
> This change introduces a new master variable to allow interface 
> drivers
> to specify that 16bit data transfer I/O is required.  This change 
> also
> introduces the ability to set this variable via device tree bindings 
> in
> the MMIO interface driver.
> 
> Before this change, on a picoXcell pc3x3:
>  spi_master spi32766: interrupt_transfer: fifo overrun/underrun
>  m25p80 spi32766.0: error -5 reading 9f
>  m25p80: probe of spi32766.0 failed with error -5
> 
> After this change:
>  m25p80 spi32766.0: m25p40 (512 Kbytes)

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

> 
> Fixes: dd11444327ce ("spi: dw-spi: Convert 16bit accesses to 32bit 
> accesses")
> Signed-off-by: Michael van der Westhuizen <michael@smart-africa.com>
> ---
> 
> Changes in v2:
>   - Incorporate review feedback from Andy Shevchenko
>     - Rework the DT bindings to accept an I/O register width as a
>       number of bytes rather than using a boolean spefifying the
>       width preference to be 16 bits.
>     - Add data register access wrapper functions and use them when
>       reading and writing the data register.
> 
>  drivers/spi/spi-dw-mmio.c |  4 ++++
>  drivers/spi/spi-dw.c      |  4 ++--
>  drivers/spi/spi-dw.h      | 35 +++++++++++++++++++++++++++++++++++
>  3 files changed, 41 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c
> index eb03e12..e76bf72 100644
> --- a/drivers/spi/spi-dw-mmio.c
> +++ b/drivers/spi/spi-dw-mmio.c
> @@ -74,6 +74,10 @@ static int dw_spi_mmio_probe(struct 
> platform_device *pdev)
>  
>  	dws->max_freq = clk_get_rate(dwsmmio->clk);
>  
> +	if (pdev->dev.of_node)
> +		of_property_read_u32(pdev->dev.of_node, "snps,reg-io
> -width",
> +				     &dws->reg_io_width);
> +
>  	num_cs = 4;
>  
>  	if (pdev->dev.of_node)
> diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
> index 8d67d03..4fbfcdc 100644
> --- a/drivers/spi/spi-dw.c
> +++ b/drivers/spi/spi-dw.c
> @@ -194,7 +194,7 @@ static void dw_writer(struct dw_spi *dws)
>  			else
>  				txw = *(u16 *)(dws->tx);
>  		}
> -		dw_writel(dws, DW_SPI_DR, txw);
> +		dw_write_io_reg(dws, DW_SPI_DR, txw);
>  		dws->tx += dws->n_bytes;
>  	}
>  }
> @@ -205,7 +205,7 @@ static void dw_reader(struct dw_spi *dws)
>  	u16 rxw;
>  
>  	while (max--) {
> -		rxw = dw_readl(dws, DW_SPI_DR);
> +		rxw = dw_read_io_reg(dws, DW_SPI_DR);
>  		/* Care rx only if the transfer's original "rx" is 
> not null */
>  		if (dws->rx_end - dws->len) {
>  			if (dws->n_bytes == 1)
> diff --git a/drivers/spi/spi-dw.h b/drivers/spi/spi-dw.h
> index 6c91391..b75ed32 100644
> --- a/drivers/spi/spi-dw.h
> +++ b/drivers/spi/spi-dw.h
> @@ -109,6 +109,7 @@ struct dw_spi {
>  	u32			fifo_len;	/* depth of the FIFO 
> buffer */
>  	u32			max_freq;	/* max bus freq 
> supported */
>  
> +	u32			reg_io_width;	/* DR I/O width in 
> bytes */
>  	u16			bus_num;
>  	u16			num_cs;		/* supported 
> slave numbers */
>  
> @@ -145,11 +146,45 @@ static inline u32 dw_readl(struct dw_spi *dws, 
> u32 offset)
>  	return __raw_readl(dws->regs + offset);
>  }
>  
> +static inline u16 dw_readw(struct dw_spi *dws, u32 offset)
> +{
> +	return __raw_readw(dws->regs + offset);
> +}
> +
>  static inline void dw_writel(struct dw_spi *dws, u32 offset, u32 
> val)
>  {
>  	__raw_writel(val, dws->regs + offset);
>  }
>  
> +static inline void dw_writew(struct dw_spi *dws, u32 offset, u16 
> val)
> +{
> +	__raw_writew(val, dws->regs + offset);
> +}
> +
> +static inline u32 dw_read_io_reg(struct dw_spi *dws, u32 offset)
> +{
> +	switch (dws->reg_io_width) {
> +	case 2:
> +		return dw_readw(dws, offset);
> +	case 4:
> +	default:
> +		return dw_readl(dws, offset);
> +	}
> +}
> +
> +static inline void dw_write_io_reg(struct dw_spi *dws, u32 offset, 
> u32 val)
> +{
> +	switch (dws->reg_io_width) {
> +	case 2:
> +		dw_writew(dws, offset, val);
> +		break;
> +	case 4:
> +	default:
> +		dw_writel(dws, offset, val);
> +		break;
> +	}
> +}
> +
>  static inline void spi_enable_chip(struct dw_spi *dws, int enable)
>  {
>  	dw_writel(dws, DW_SPI_SSIENR, (enable ? 1 : 0));

-- 
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy

Re: [PATCH v2 0/2] spi: dw: Reintroduce optional 16 bit data register I/O

[Andy Shevchenko]

On Wed, 2015-06-24 at 18:34 +0200, Michael van der Westhuizen wrote:
> The commit dd11444327ce ("spi: dw-spi: Convert 16bit accesses to 
> 32bit
> accesses") globally changed all register access in the dw_apb_ssi 
> driver
> to 32 bit access, which breaks data register (FIFO) access on 
> picoXcell
> platforms.
> 
> This series introduces a boolean to the core spi-dw driver to 
> indicate
> to the core that 16 bit data register access is appropriate, 
> implements
> the code that respects that flag and updates the dw-spi-mmio driver 
> to
> allow setting this boolean from the device tree.
> 
> A binding documentation fix is included in this series.
> 
> Prior to applying this change the following error presents on
> a picoCell pc3x3 platform:
>   spi_master spi32766: interrupt_transfer: fifo overrun/underrun
>   m25p80 spi32766.0: error -5 reading 9f
>   m25p80: probe of spi32766.0 failed with error -5
> 
> With this series applied:
>   m25p80 spi32766.0: m25p40 (512 Kbytes)

Mark, what do you think about this? For me it looks okay.

> 
> Changes in v2:
>   - Incorporate review feedback from Andy Shevchenko, reworking the
>     bindings to reflect common practice and adjusting the driver
>     to suit.
>   - Add a wrapper inline function for accessing the data register
>     using the configured with.
> 
> Michael van der Westhuizen (2):
>   dt: snps,dw-apb-ssi: Document new I/O data register width property
>   spi: dw: Allow interface drivers to limit data I/O to word sizes
> 
>  drivers/spi/spi-dw-mmio.c |  4 ++++
>  drivers/spi/spi-dw.c      |  4 ++--
>  drivers/spi/spi-dw.h      | 35 +++++++++++++++++++++++++++++++++++
>  3 files changed, 41 insertions(+), 2 deletions(-)
> 

-- 
Andy Shevchenko <andriy.shevchenko-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
Intel Finland Oy
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
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[PATCH v2 0/2] spi: dw: Reintroduce optional 16 bit data register I/O

[Andy Shevchenko]

On Wed, 2015-06-24 at 18:34 +0200, Michael van der Westhuizen wrote:
> The commit dd11444327ce ("spi: dw-spi: Convert 16bit accesses to 
> 32bit
> accesses") globally changed all register access in the dw_apb_ssi 
> driver
> to 32 bit access, which breaks data register (FIFO) access on 
> picoXcell
> platforms.
> 
> This series introduces a boolean to the core spi-dw driver to 
> indicate
> to the core that 16 bit data register access is appropriate, 
> implements
> the code that respects that flag and updates the dw-spi-mmio driver 
> to
> allow setting this boolean from the device tree.
> 
> A binding documentation fix is included in this series.
> 
> Prior to applying this change the following error presents on
> a picoCell pc3x3 platform:
>   spi_master spi32766: interrupt_transfer: fifo overrun/underrun
>   m25p80 spi32766.0: error -5 reading 9f
>   m25p80: probe of spi32766.0 failed with error -5
> 
> With this series applied:
>   m25p80 spi32766.0: m25p40 (512 Kbytes)

Mark, what do you think about this? For me it looks okay.

> 
> Changes in v2:
>   - Incorporate review feedback from Andy Shevchenko, reworking the
>     bindings to reflect common practice and adjusting the driver
>     to suit.
>   - Add a wrapper inline function for accessing the data register
>     using the configured with.
> 
> Michael van der Westhuizen (2):
>   dt: snps,dw-apb-ssi: Document new I/O data register width property
>   spi: dw: Allow interface drivers to limit data I/O to word sizes
> 
>  drivers/spi/spi-dw-mmio.c |  4 ++++
>  drivers/spi/spi-dw.c      |  4 ++--
>  drivers/spi/spi-dw.h      | 35 +++++++++++++++++++++++++++++++++++
>  3 files changed, 41 insertions(+), 2 deletions(-)
> 

-- 
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy

Re: [PATCH v2 0/2] spi: dw: Reintroduce optional 16 bit data register I/O

[Mark Brown]

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On Fri, Jul 24, 2015 at 06:30:12PM +0300, Andy Shevchenko wrote:
> On Wed, 2015-06-24 at 18:34 +0200, Michael van der Westhuizen wrote:

> > With this series applied:
> >   m25p80 spi32766.0: m25p40 (512 Kbytes)

> Mark, what do you think about this? For me it looks okay.

Please don't send content free pings, if you want me to review a patch
please send me the patch.

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[PATCH v2 0/2] spi: dw: Reintroduce optional 16 bit data register I/O

[Mark Brown]

On Fri, Jul 24, 2015 at 06:30:12PM +0300, Andy Shevchenko wrote:
> On Wed, 2015-06-24 at 18:34 +0200, Michael van der Westhuizen wrote:

> > With this series applied:
> >   m25p80 spi32766.0: m25p40 (512 Kbytes)

> Mark, what do you think about this? For me it looks okay.

Please don't send content free pings, if you want me to review a patch
please send me the patch.
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Re: [PATCH v2 0/2] spi: dw: Reintroduce optional 16 bit data register I/O

[Andy Shevchenko]

On Fri, 2015-07-24 at 16:37 +0100, Mark Brown wrote:
> On Fri, Jul 24, 2015 at 06:30:12PM +0300, Andy Shevchenko wrote:
> > On Wed, 2015-06-24 at 18:34 +0200, Michael van der Westhuizen 
> > wrote:
> 
> > > With this series applied:
> > >   m25p80 spi32766.0: m25p40 (512 Kbytes)
> 
> > Mark, what do you think about this? For me it looks okay.
> 
> Please don't send content free pings, if you want me to review a 
> patch
> please send me the patch.

Hmm… It's strange since patch series was sent to mailing list (Cc'ed to
you) on 24.06 [1].

[1] 
https://www.mail-archive.com/linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org/msg05530.html

P.S. It has not mine authorship, though I can resend the series if
needed.

-- 
Andy Shevchenko <andriy.shevchenko-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
Intel Finland Oy
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
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[PATCH v2 0/2] spi: dw: Reintroduce optional 16 bit data register I/O

[Andy Shevchenko]

On Fri, 2015-07-24 at 16:37 +0100, Mark Brown wrote:
> On Fri, Jul 24, 2015 at 06:30:12PM +0300, Andy Shevchenko wrote:
> > On Wed, 2015-06-24 at 18:34 +0200, Michael van der Westhuizen 
> > wrote:
> 
> > > With this series applied:
> > >   m25p80 spi32766.0: m25p40 (512 Kbytes)
> 
> > Mark, what do you think about this? For me it looks okay.
> 
> Please don't send content free pings, if you want me to review a 
> patch
> please send me the patch.

Hmm? It's strange since patch series was sent to mailing list (Cc'ed to
you) on 24.06 [1].

[1] 
https://www.mail-archive.com/linux-spi at vger.kernel.org/msg05530.html

P.S. It has not mine authorship, though I can resend the series if
needed.

-- 
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy

Re: [PATCH v2 0/2] spi: dw: Reintroduce optional 16 bit data register I/O

[Mark Brown]

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On Mon, Jul 27, 2015 at 01:58:11PM +0300, Andy Shevchenko wrote:
> On Fri, 2015-07-24 at 16:37 +0100, Mark Brown wrote:

> > Please don't send content free pings, if you want me to review a 
> > patch
> > please send me the patch.

> Hmm… It's strange since patch series was sent to mailing list (Cc'ed to
> you) on 24.06 [1].

> [1] 
> https://www.mail-archive.com/linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org/msg05530.html

> P.S. It has not mine authorship, though I can resend the series if
> needed.

It's possible there was some discussion of the patch that made
it look it needed a resubmit, or that it was buried as reply in the
middle of discussion of some other patches (eg, a previous version).
Either way to repeat what I said if you want me to review a patch please
send me the patch.

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[PATCH v2 0/2] spi: dw: Reintroduce optional 16 bit data register I/O

[Mark Brown]

On Mon, Jul 27, 2015 at 01:58:11PM +0300, Andy Shevchenko wrote:
> On Fri, 2015-07-24 at 16:37 +0100, Mark Brown wrote:

> > Please don't send content free pings, if you want me to review a 
> > patch
> > please send me the patch.

> Hmm? It's strange since patch series was sent to mailing list (Cc'ed to
> you) on 24.06 [1].

> [1] 
> https://www.mail-archive.com/linux-spi at vger.kernel.org/msg05530.html

> P.S. It has not mine authorship, though I can resend the series if
> needed.

It's possible there was some discussion of the patch that made
it look it needed a resubmit, or that it was buried as reply in the
middle of discussion of some other patches (eg, a previous version).
Either way to repeat what I said if you want me to review a patch please
send me the patch.
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[RESEND PATCH v2 0/2] spi: dw: Reintroduce optional 16 bit data register I/O

[Michael van der Westhuizen]

The commit dd11444327ce ("spi: dw-spi: Convert 16bit accesses to 32bit
accesses") globally changed all register access in the dw_apb_ssi driver
to 32 bit access, which breaks data register (FIFO) access on picoXcell
platforms.

This series introduces a boolean to the core spi-dw driver to indicate
to the core that 16 bit data register access is appropriate, implements
the code that respects that flag and updates the dw-spi-mmio driver to
allow setting this boolean from the device tree.

A binding documentation fix is included in this series.

Prior to applying this change the following error presents on
a picoCell pc3x3 platform:
  spi_master spi32766: interrupt_transfer: fifo overrun/underrun
  m25p80 spi32766.0: error -5 reading 9f
  m25p80: probe of spi32766.0 failed with error -5

With this series applied:
  m25p80 spi32766.0: m25p40 (512 Kbytes)

(Resend requested by Mark Brown)

Changes in v2:
  - Incorporate review feedback from Andy Shevchenko, reworking the
    bindings to reflect common practice and adjusting the driver
    to suit.
  - Add a wrapper inline function for accessing the data register
    using the configured with.

Michael van der Westhuizen (2):
  dt: snps,dw-apb-ssi: Document new I/O data register width property
  spi: dw: Allow interface drivers to limit data I/O to word sizes

 drivers/spi/spi-dw-mmio.c |  4 ++++
 drivers/spi/spi-dw.c      |  4 ++--
 drivers/spi/spi-dw.h      | 35 +++++++++++++++++++++++++++++++++++
 3 files changed, 41 insertions(+), 2 deletions(-)

-- 
2.1.4

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[RESEND PATCH v2 0/2] spi: dw: Reintroduce optional 16 bit data register I/O

[Michael van der Westhuizen]

The commit dd11444327ce ("spi: dw-spi: Convert 16bit accesses to 32bit
accesses") globally changed all register access in the dw_apb_ssi driver
to 32 bit access, which breaks data register (FIFO) access on picoXcell
platforms.

This series introduces a boolean to the core spi-dw driver to indicate
to the core that 16 bit data register access is appropriate, implements
the code that respects that flag and updates the dw-spi-mmio driver to
allow setting this boolean from the device tree.

A binding documentation fix is included in this series.

Prior to applying this change the following error presents on
a picoCell pc3x3 platform:
  spi_master spi32766: interrupt_transfer: fifo overrun/underrun
  m25p80 spi32766.0: error -5 reading 9f
  m25p80: probe of spi32766.0 failed with error -5

With this series applied:
  m25p80 spi32766.0: m25p40 (512 Kbytes)

(Resend requested by Mark Brown)

Changes in v2:
  - Incorporate review feedback from Andy Shevchenko, reworking the
    bindings to reflect common practice and adjusting the driver
    to suit.
  - Add a wrapper inline function for accessing the data register
    using the configured with.

Michael van der Westhuizen (2):
  dt: snps,dw-apb-ssi: Document new I/O data register width property
  spi: dw: Allow interface drivers to limit data I/O to word sizes

 drivers/spi/spi-dw-mmio.c |  4 ++++
 drivers/spi/spi-dw.c      |  4 ++--
 drivers/spi/spi-dw.h      | 35 +++++++++++++++++++++++++++++++++++
 3 files changed, 41 insertions(+), 2 deletions(-)

-- 
2.1.4

[RESEND PATCH v2 1/2] dt: snps,dw-apb-ssi: Document new I/O data register width property

[Michael van der Westhuizen]

This change documents a new property for the snps,dw-apb-ssi device,
allowing an implementer to specify either four byte or two bytes
access to the SPI controller data register.

This supports a change that unbreaks this driver on picoXcell
platforms.

Signed-off-by: Michael van der Westhuizen <michael-XrNoQAPr3WXM9gW82pYGhQ@public.gmane.org>
---

Changes in v2:
  - Incorporate review feedback from Andy Shevchenko, reworking the
    bindings to reflect common practice.

 Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt b/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt
index bd99193..b4f1086 100644
--- a/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt
+++ b/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt
@@ -10,6 +10,8 @@ Required properties:
 Optional properties:
 - cs-gpios : Specifies the gpio pis to be used for chipselects.
 - num-cs : The number of chipselects. If omitted, this will default to 4.
+- snps,reg-io-width : The I/O register width (in bytes) implemented by
+  this device.  Supported values are 2 or 4 (the default).
 
 Child nodes as per the generic SPI binding.
 
-- 
2.1.4

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[RESEND PATCH v2 1/2] dt: snps, dw-apb-ssi: Document new I/O data register width property

[Michael van der Westhuizen]

This change documents a new property for the snps,dw-apb-ssi device,
allowing an implementer to specify either four byte or two bytes
access to the SPI controller data register.

This supports a change that unbreaks this driver on picoXcell
platforms.

Signed-off-by: Michael van der Westhuizen <michael@smart-africa.com>
---

Changes in v2:
  - Incorporate review feedback from Andy Shevchenko, reworking the
    bindings to reflect common practice.

 Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt b/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt
index bd99193..b4f1086 100644
--- a/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt
+++ b/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt
@@ -10,6 +10,8 @@ Required properties:
 Optional properties:
 - cs-gpios : Specifies the gpio pis to be used for chipselects.
 - num-cs : The number of chipselects. If omitted, this will default to 4.
+- snps,reg-io-width : The I/O register width (in bytes) implemented by
+  this device.  Supported values are 2 or 4 (the default).
 
 Child nodes as per the generic SPI binding.
 
-- 
2.1.4

[RESEND PATCH v2 2/2] spi: dw: Allow interface drivers to limit data I/O to word sizes

[Michael van der Westhuizen]

The commit dd11444327ce ("spi: dw-spi: Convert 16bit accesses to 32bit
accesses") changed all 16bit accesses in the DW_apb_ssi driver to 32bit.
This, unfortunately, breaks data register access on picoXcell, where the
DW IP needs data register accesses to be word accesses (all other
accesses appear to be OK).

This change introduces a new master variable to allow interface drivers
to specify that 16bit data transfer I/O is required.  This change also
introduces the ability to set this variable via device tree bindings in
the MMIO interface driver.

Before this change, on a picoXcell pc3x3:
 spi_master spi32766: interrupt_transfer: fifo overrun/underrun
 m25p80 spi32766.0: error -5 reading 9f
 m25p80: probe of spi32766.0 failed with error -5

After this change:
 m25p80 spi32766.0: m25p40 (512 Kbytes)

Fixes: dd11444327ce ("spi: dw-spi: Convert 16bit accesses to 32bit accesses")
Signed-off-by: Michael van der Westhuizen <michael-XrNoQAPr3WXM9gW82pYGhQ@public.gmane.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
---

Changes in v2:
  - Incorporate review feedback from Andy Shevchenko
    - Rework the DT bindings to accept an I/O register width as a
      number of bytes rather than using a boolean spefifying the
      width preference to be 16 bits.
    - Add data register access wrapper functions and use them when
      reading and writing the data register.

 drivers/spi/spi-dw-mmio.c |  4 ++++
 drivers/spi/spi-dw.c      |  4 ++--
 drivers/spi/spi-dw.h      | 35 +++++++++++++++++++++++++++++++++++
 3 files changed, 41 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c
index eb03e12..e76bf72 100644
--- a/drivers/spi/spi-dw-mmio.c
+++ b/drivers/spi/spi-dw-mmio.c
@@ -74,6 +74,10 @@ static int dw_spi_mmio_probe(struct platform_device *pdev)
 
 	dws->max_freq = clk_get_rate(dwsmmio->clk);
 
+	if (pdev->dev.of_node)
+		of_property_read_u32(pdev->dev.of_node, "snps,reg-io-width",
+				     &dws->reg_io_width);
+
 	num_cs = 4;
 
 	if (pdev->dev.of_node)
diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
index 8d67d03..4fbfcdc 100644
--- a/drivers/spi/spi-dw.c
+++ b/drivers/spi/spi-dw.c
@@ -194,7 +194,7 @@ static void dw_writer(struct dw_spi *dws)
 			else
 				txw = *(u16 *)(dws->tx);
 		}
-		dw_writel(dws, DW_SPI_DR, txw);
+		dw_write_io_reg(dws, DW_SPI_DR, txw);
 		dws->tx += dws->n_bytes;
 	}
 }
@@ -205,7 +205,7 @@ static void dw_reader(struct dw_spi *dws)
 	u16 rxw;
 
 	while (max--) {
-		rxw = dw_readl(dws, DW_SPI_DR);
+		rxw = dw_read_io_reg(dws, DW_SPI_DR);
 		/* Care rx only if the transfer's original "rx" is not null */
 		if (dws->rx_end - dws->len) {
 			if (dws->n_bytes == 1)
diff --git a/drivers/spi/spi-dw.h b/drivers/spi/spi-dw.h
index 6c91391..b75ed32 100644
--- a/drivers/spi/spi-dw.h
+++ b/drivers/spi/spi-dw.h
@@ -109,6 +109,7 @@ struct dw_spi {
 	u32			fifo_len;	/* depth of the FIFO buffer */
 	u32			max_freq;	/* max bus freq supported */
 
+	u32			reg_io_width;	/* DR I/O width in bytes */
 	u16			bus_num;
 	u16			num_cs;		/* supported slave numbers */
 
@@ -145,11 +146,45 @@ static inline u32 dw_readl(struct dw_spi *dws, u32 offset)
 	return __raw_readl(dws->regs + offset);
 }
 
+static inline u16 dw_readw(struct dw_spi *dws, u32 offset)
+{
+	return __raw_readw(dws->regs + offset);
+}
+
 static inline void dw_writel(struct dw_spi *dws, u32 offset, u32 val)
 {
 	__raw_writel(val, dws->regs + offset);
 }
 
+static inline void dw_writew(struct dw_spi *dws, u32 offset, u16 val)
+{
+	__raw_writew(val, dws->regs + offset);
+}
+
+static inline u32 dw_read_io_reg(struct dw_spi *dws, u32 offset)
+{
+	switch (dws->reg_io_width) {
+	case 2:
+		return dw_readw(dws, offset);
+	case 4:
+	default:
+		return dw_readl(dws, offset);
+	}
+}
+
+static inline void dw_write_io_reg(struct dw_spi *dws, u32 offset, u32 val)
+{
+	switch (dws->reg_io_width) {
+	case 2:
+		dw_writew(dws, offset, val);
+		break;
+	case 4:
+	default:
+		dw_writel(dws, offset, val);
+		break;
+	}
+}
+
 static inline void spi_enable_chip(struct dw_spi *dws, int enable)
 {
 	dw_writel(dws, DW_SPI_SSIENR, (enable ? 1 : 0));
-- 
2.1.4

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[RESEND PATCH v2 2/2] spi: dw: Allow interface drivers to limit data I/O to word sizes

[Michael van der Westhuizen]

The commit dd11444327ce ("spi: dw-spi: Convert 16bit accesses to 32bit
accesses") changed all 16bit accesses in the DW_apb_ssi driver to 32bit.
This, unfortunately, breaks data register access on picoXcell, where the
DW IP needs data register accesses to be word accesses (all other
accesses appear to be OK).

This change introduces a new master variable to allow interface drivers
to specify that 16bit data transfer I/O is required.  This change also
introduces the ability to set this variable via device tree bindings in
the MMIO interface driver.

Before this change, on a picoXcell pc3x3:
 spi_master spi32766: interrupt_transfer: fifo overrun/underrun
 m25p80 spi32766.0: error -5 reading 9f
 m25p80: probe of spi32766.0 failed with error -5

After this change:
 m25p80 spi32766.0: m25p40 (512 Kbytes)

Fixes: dd11444327ce ("spi: dw-spi: Convert 16bit accesses to 32bit accesses")
Signed-off-by: Michael van der Westhuizen <michael@smart-africa.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---

Changes in v2:
  - Incorporate review feedback from Andy Shevchenko
    - Rework the DT bindings to accept an I/O register width as a
      number of bytes rather than using a boolean spefifying the
      width preference to be 16 bits.
    - Add data register access wrapper functions and use them when
      reading and writing the data register.

 drivers/spi/spi-dw-mmio.c |  4 ++++
 drivers/spi/spi-dw.c      |  4 ++--
 drivers/spi/spi-dw.h      | 35 +++++++++++++++++++++++++++++++++++
 3 files changed, 41 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c
index eb03e12..e76bf72 100644
--- a/drivers/spi/spi-dw-mmio.c
+++ b/drivers/spi/spi-dw-mmio.c
@@ -74,6 +74,10 @@ static int dw_spi_mmio_probe(struct platform_device *pdev)
 
 	dws->max_freq = clk_get_rate(dwsmmio->clk);
 
+	if (pdev->dev.of_node)
+		of_property_read_u32(pdev->dev.of_node, "snps,reg-io-width",
+				     &dws->reg_io_width);
+
 	num_cs = 4;
 
 	if (pdev->dev.of_node)
diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
index 8d67d03..4fbfcdc 100644
--- a/drivers/spi/spi-dw.c
+++ b/drivers/spi/spi-dw.c
@@ -194,7 +194,7 @@ static void dw_writer(struct dw_spi *dws)
 			else
 				txw = *(u16 *)(dws->tx);
 		}
-		dw_writel(dws, DW_SPI_DR, txw);
+		dw_write_io_reg(dws, DW_SPI_DR, txw);
 		dws->tx += dws->n_bytes;
 	}
 }
@@ -205,7 +205,7 @@ static void dw_reader(struct dw_spi *dws)
 	u16 rxw;
 
 	while (max--) {
-		rxw = dw_readl(dws, DW_SPI_DR);
+		rxw = dw_read_io_reg(dws, DW_SPI_DR);
 		/* Care rx only if the transfer's original "rx" is not null */
 		if (dws->rx_end - dws->len) {
 			if (dws->n_bytes == 1)
diff --git a/drivers/spi/spi-dw.h b/drivers/spi/spi-dw.h
index 6c91391..b75ed32 100644
--- a/drivers/spi/spi-dw.h
+++ b/drivers/spi/spi-dw.h
@@ -109,6 +109,7 @@ struct dw_spi {
 	u32			fifo_len;	/* depth of the FIFO buffer */
 	u32			max_freq;	/* max bus freq supported */
 
+	u32			reg_io_width;	/* DR I/O width in bytes */
 	u16			bus_num;
 	u16			num_cs;		/* supported slave numbers */
 
@@ -145,11 +146,45 @@ static inline u32 dw_readl(struct dw_spi *dws, u32 offset)
 	return __raw_readl(dws->regs + offset);
 }
 
+static inline u16 dw_readw(struct dw_spi *dws, u32 offset)
+{
+	return __raw_readw(dws->regs + offset);
+}
+
 static inline void dw_writel(struct dw_spi *dws, u32 offset, u32 val)
 {
 	__raw_writel(val, dws->regs + offset);
 }
 
+static inline void dw_writew(struct dw_spi *dws, u32 offset, u16 val)
+{
+	__raw_writew(val, dws->regs + offset);
+}
+
+static inline u32 dw_read_io_reg(struct dw_spi *dws, u32 offset)
+{
+	switch (dws->reg_io_width) {
+	case 2:
+		return dw_readw(dws, offset);
+	case 4:
+	default:
+		return dw_readl(dws, offset);
+	}
+}
+
+static inline void dw_write_io_reg(struct dw_spi *dws, u32 offset, u32 val)
+{
+	switch (dws->reg_io_width) {
+	case 2:
+		dw_writew(dws, offset, val);
+		break;
+	case 4:
+	default:
+		dw_writel(dws, offset, val);
+		break;
+	}
+}
+
 static inline void spi_enable_chip(struct dw_spi *dws, int enable)
 {
 	dw_writel(dws, DW_SPI_SSIENR, (enable ? 1 : 0));
-- 
2.1.4

Re: [PATCH v2 0/2] spi: dw: Reintroduce optional 16 bit data register I/O

[Michael van der Westhuizen]

Hi Mark,

> On 27 Jul 2015, at 1:19 PM, Mark Brown <broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> wrote:
> 
> On Mon, Jul 27, 2015 at 01:58:11PM +0300, Andy Shevchenko wrote:
>> On Fri, 2015-07-24 at 16:37 +0100, Mark Brown wrote:
> 
>>> Please don't send content free pings, if you want me to review a 
>>> patch
>>> please send me the patch.
> 
>> Hmm… It's strange since patch series was sent to mailing list (Cc'ed to
>> you) on 24.06 [1].
> 
>> [1] 
>> https://www.mail-archive.com/linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org/msg05530.html
> 
>> P.S. It has not mine authorship, though I can resend the series if
>> needed.
> 
> It's possible there was some discussion of the patch that made
> it look it needed a resubmit, or that it was buried as reply in the
> middle of discussion of some other patches (eg, a previous version).
> Either way to repeat what I said if you want me to review a patch please
> send me the patch.

I’ve just resent the series.

Michael

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[PATCH v2 0/2] spi: dw: Reintroduce optional 16 bit data register I/O

[Michael van der Westhuizen]

Hi Mark,

> On 27 Jul 2015, at 1:19 PM, Mark Brown <broonie@kernel.org> wrote:
> 
> On Mon, Jul 27, 2015 at 01:58:11PM +0300, Andy Shevchenko wrote:
>> On Fri, 2015-07-24 at 16:37 +0100, Mark Brown wrote:
> 
>>> Please don't send content free pings, if you want me to review a 
>>> patch
>>> please send me the patch.
> 
>> Hmm? It's strange since patch series was sent to mailing list (Cc'ed to
>> you) on 24.06 [1].
> 
>> [1] 
>> https://www.mail-archive.com/linux-spi at vger.kernel.org/msg05530.html
> 
>> P.S. It has not mine authorship, though I can resend the series if
>> needed.
> 
> It's possible there was some discussion of the patch that made
> it look it needed a resubmit, or that it was buried as reply in the
> middle of discussion of some other patches (eg, a previous version).
> Either way to repeat what I said if you want me to review a patch please
> send me the patch.

I?ve just resent the series.

Michael

Re: [RESEND PATCH v2 1/2] dt: snps,dw-apb-ssi: Document new I/O data register width property

[Rob Herring]

On Mon, Jul 27, 2015 at 6:37 AM, Michael van der Westhuizen
<michael-XrNoQAPr3WXM9gW82pYGhQ@public.gmane.org> wrote:
> This change documents a new property for the snps,dw-apb-ssi device,
> allowing an implementer to specify either four byte or two bytes
> access to the SPI controller data register.
>
> This supports a change that unbreaks this driver on picoXcell
> platforms.
>
> Signed-off-by: Michael van der Westhuizen <michael-XrNoQAPr3WXM9gW82pYGhQ@public.gmane.org>
> ---
>
> Changes in v2:
>   - Incorporate review feedback from Andy Shevchenko, reworking the
>     bindings to reflect common practice.
>
>  Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt b/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt
> index bd99193..b4f1086 100644
> --- a/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt
> +++ b/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt
> @@ -10,6 +10,8 @@ Required properties:
>  Optional properties:
>  - cs-gpios : Specifies the gpio pis to be used for chipselects.
>  - num-cs : The number of chipselects. If omitted, this will default to 4.
> +- snps,reg-io-width : The I/O register width (in bytes) implemented by
> +  this device.  Supported values are 2 or 4 (the default).

Drop the snps as this is already a common property (at least for UARTs).

Rob
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[RESEND PATCH v2 1/2] dt: snps, dw-apb-ssi: Document new I/O data register width property

[Rob Herring]

On Mon, Jul 27, 2015 at 6:37 AM, Michael van der Westhuizen
<michael@smart-africa.com> wrote:
> This change documents a new property for the snps,dw-apb-ssi device,
> allowing an implementer to specify either four byte or two bytes
> access to the SPI controller data register.
>
> This supports a change that unbreaks this driver on picoXcell
> platforms.
>
> Signed-off-by: Michael van der Westhuizen <michael@smart-africa.com>
> ---
>
> Changes in v2:
>   - Incorporate review feedback from Andy Shevchenko, reworking the
>     bindings to reflect common practice.
>
>  Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt b/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt
> index bd99193..b4f1086 100644
> --- a/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt
> +++ b/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt
> @@ -10,6 +10,8 @@ Required properties:
>  Optional properties:
>  - cs-gpios : Specifies the gpio pis to be used for chipselects.
>  - num-cs : The number of chipselects. If omitted, this will default to 4.
> +- snps,reg-io-width : The I/O register width (in bytes) implemented by
> +  this device.  Supported values are 2 or 4 (the default).

Drop the snps as this is already a common property (at least for UARTs).

Rob

Re: [PATCH v2 0/2] spi: dw: Reintroduce optional 16 bit data register I/O

[Mark Brown]

[-- Attachment #1: Type: text/plain, Size: 819 bytes --]

On Mon, Jul 27, 2015 at 01:38:57PM +0200, Michael van der Westhuizen wrote:

> > It's possible there was some discussion of the patch that made
> > it look it needed a resubmit, or that it was buried as reply in the
> > middle of discussion of some other patches (eg, a previous version).
> > Either way to repeat what I said if you want me to review a patch please
> > send me the patch.

> I’ve just resent the series.

You've sent them as a reply in the middle of another thread which is
something I just indicated above was a bad idea in the message you're
replying to here (it's a great way to either make it hard to figure out
what the current version of the code is or get your message deleted
along with the rest of the thread) and you've decided to label them as
[RESEND instead of [PATCH :(

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 473 bytes --]

[PATCH v2 0/2] spi: dw: Reintroduce optional 16 bit data register I/O

[Mark Brown]

On Mon, Jul 27, 2015 at 01:38:57PM +0200, Michael van der Westhuizen wrote:

> > It's possible there was some discussion of the patch that made
> > it look it needed a resubmit, or that it was buried as reply in the
> > middle of discussion of some other patches (eg, a previous version).
> > Either way to repeat what I said if you want me to review a patch please
> > send me the patch.

> I?ve just resent the series.

You've sent them as a reply in the middle of another thread which is
something I just indicated above was a bad idea in the message you're
replying to here (it's a great way to either make it hard to figure out
what the current version of the code is or get your message deleted
along with the rest of the thread) and you've decided to label them as
[RESEND instead of [PATCH :(
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Re: [PATCH v2 0/2] spi: dw: Reintroduce optional 16 bit data register I/O

[Andy Shevchenko]

On Mon, Jul 27, 2015 at 4:59 PM, Mark Brown <broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> wrote:
> On Mon, Jul 27, 2015 at 01:38:57PM +0200, Michael van der Westhuizen wrote:
>
>> > It's possible there was some discussion of the patch that made
>> > it look it needed a resubmit, or that it was buried as reply in the
>> > middle of discussion of some other patches (eg, a previous version).
>> > Either way to repeat what I said if you want me to review a patch please
>> > send me the patch.
>
>> I’ve just resent the series.
>
> You've sent them as a reply in the middle of another thread which is
> something I just indicated above was a bad idea in the message you're
> replying to here (it's a great way to either make it hard to figure out
> what the current version of the code is or get your message deleted
> along with the rest of the thread) and you've decided to label them as
> [RESEND instead of [PATCH :(

Michael, I believe you need to resend as a v3 in a separate thread if
you aware of this code.
(Though it seems already late for v4.3)

-- 
With Best Regards,
Andy Shevchenko
--
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[PATCH v2 0/2] spi: dw: Reintroduce optional 16 bit data register I/O

[Andy Shevchenko]

On Mon, Jul 27, 2015 at 4:59 PM, Mark Brown <broonie@kernel.org> wrote:
> On Mon, Jul 27, 2015 at 01:38:57PM +0200, Michael van der Westhuizen wrote:
>
>> > It's possible there was some discussion of the patch that made
>> > it look it needed a resubmit, or that it was buried as reply in the
>> > middle of discussion of some other patches (eg, a previous version).
>> > Either way to repeat what I said if you want me to review a patch please
>> > send me the patch.
>
>> I?ve just resent the series.
>
> You've sent them as a reply in the middle of another thread which is
> something I just indicated above was a bad idea in the message you're
> replying to here (it's a great way to either make it hard to figure out
> what the current version of the code is or get your message deleted
> along with the rest of the thread) and you've decided to label them as
> [RESEND instead of [PATCH :(

Michael, I believe you need to resend as a v3 in a separate thread if
you aware of this code.
(Though it seems already late for v4.3)

-- 
With Best Regards,
Andy Shevchenko

Re: [RESEND PATCH v2 2/2] spi: dw: Allow interface drivers to limit data I/O to word sizes

[Andy Shevchenko]

On Mon, Jul 27, 2015 at 2:37 PM, Michael van der Westhuizen
<michael-XrNoQAPr3WXM9gW82pYGhQ@public.gmane.org> wrote:
> The commit dd11444327ce ("spi: dw-spi: Convert 16bit accesses to 32bit
> accesses") changed all 16bit accesses in the DW_apb_ssi driver to 32bit.
> This, unfortunately, breaks data register access on picoXcell, where the
> DW IP needs data register accesses to be word accesses (all other
> accesses appear to be OK).
>
> This change introduces a new master variable to allow interface drivers
> to specify that 16bit data transfer I/O is required.  This change also
> introduces the ability to set this variable via device tree bindings in
> the MMIO interface driver.
>
> Before this change, on a picoXcell pc3x3:
>  spi_master spi32766: interrupt_transfer: fifo overrun/underrun
>  m25p80 spi32766.0: error -5 reading 9f
>  m25p80: probe of spi32766.0 failed with error -5
>
> After this change:
>  m25p80 spi32766.0: m25p40 (512 Kbytes)
>
> Fixes: dd11444327ce ("spi: dw-spi: Convert 16bit accesses to 32bit accesses")
> Signed-off-by: Michael van der Westhuizen <michael-XrNoQAPr3WXM9gW82pYGhQ@public.gmane.org>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>

One minor comment below.

> ---
>
> Changes in v2:
>   - Incorporate review feedback from Andy Shevchenko
>     - Rework the DT bindings to accept an I/O register width as a
>       number of bytes rather than using a boolean spefifying the
>       width preference to be 16 bits.
>     - Add data register access wrapper functions and use them when
>       reading and writing the data register.
>
>  drivers/spi/spi-dw-mmio.c |  4 ++++
>  drivers/spi/spi-dw.c      |  4 ++--
>  drivers/spi/spi-dw.h      | 35 +++++++++++++++++++++++++++++++++++
>  3 files changed, 41 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c
> index eb03e12..e76bf72 100644
> --- a/drivers/spi/spi-dw-mmio.c
> +++ b/drivers/spi/spi-dw-mmio.c
> @@ -74,6 +74,10 @@ static int dw_spi_mmio_probe(struct platform_device *pdev)
>
>         dws->max_freq = clk_get_rate(dwsmmio->clk);
>
> +       if (pdev->dev.of_node)

of_property_read_u32() is NULL-aware. Since the option is optional we
may drop the condition.

> +               of_property_read_u32(pdev->dev.of_node, "snps,reg-io-width",

Like Rob said, drop 'snps,' prefix as it is a generic property name.

> +                                    &dws->reg_io_width);
> +
>         num_cs = 4;
>
>         if (pdev->dev.of_node)
> diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
> index 8d67d03..4fbfcdc 100644
> --- a/drivers/spi/spi-dw.c
> +++ b/drivers/spi/spi-dw.c
> @@ -194,7 +194,7 @@ static void dw_writer(struct dw_spi *dws)
>                         else
>                                 txw = *(u16 *)(dws->tx);
>                 }
> -               dw_writel(dws, DW_SPI_DR, txw);
> +               dw_write_io_reg(dws, DW_SPI_DR, txw);
>                 dws->tx += dws->n_bytes;
>         }
>  }
> @@ -205,7 +205,7 @@ static void dw_reader(struct dw_spi *dws)
>         u16 rxw;
>
>         while (max--) {
> -               rxw = dw_readl(dws, DW_SPI_DR);
> +               rxw = dw_read_io_reg(dws, DW_SPI_DR);
>                 /* Care rx only if the transfer's original "rx" is not null */
>                 if (dws->rx_end - dws->len) {
>                         if (dws->n_bytes == 1)
> diff --git a/drivers/spi/spi-dw.h b/drivers/spi/spi-dw.h
> index 6c91391..b75ed32 100644
> --- a/drivers/spi/spi-dw.h
> +++ b/drivers/spi/spi-dw.h
> @@ -109,6 +109,7 @@ struct dw_spi {
>         u32                     fifo_len;       /* depth of the FIFO buffer */
>         u32                     max_freq;       /* max bus freq supported */
>
> +       u32                     reg_io_width;   /* DR I/O width in bytes */
>         u16                     bus_num;
>         u16                     num_cs;         /* supported slave numbers */
>
> @@ -145,11 +146,45 @@ static inline u32 dw_readl(struct dw_spi *dws, u32 offset)
>         return __raw_readl(dws->regs + offset);
>  }
>
> +static inline u16 dw_readw(struct dw_spi *dws, u32 offset)
> +{
> +       return __raw_readw(dws->regs + offset);
> +}
> +
>  static inline void dw_writel(struct dw_spi *dws, u32 offset, u32 val)
>  {
>         __raw_writel(val, dws->regs + offset);
>  }
>
> +static inline void dw_writew(struct dw_spi *dws, u32 offset, u16 val)
> +{
> +       __raw_writew(val, dws->regs + offset);
> +}
> +
> +static inline u32 dw_read_io_reg(struct dw_spi *dws, u32 offset)
> +{
> +       switch (dws->reg_io_width) {
> +       case 2:
> +               return dw_readw(dws, offset);
> +       case 4:
> +       default:
> +               return dw_readl(dws, offset);
> +       }
> +}
> +
> +static inline void dw_write_io_reg(struct dw_spi *dws, u32 offset, u32 val)
> +{
> +       switch (dws->reg_io_width) {
> +       case 2:
> +               dw_writew(dws, offset, val);
> +               break;
> +       case 4:
> +       default:
> +               dw_writel(dws, offset, val);
> +               break;
> +       }
> +}
> +
>  static inline void spi_enable_chip(struct dw_spi *dws, int enable)
>  {
>         dw_writel(dws, DW_SPI_SSIENR, (enable ? 1 : 0));
> --
> 2.1.4
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-spi" in
> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html



-- 
With Best Regards,
Andy Shevchenko
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
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[RESEND PATCH v2 2/2] spi: dw: Allow interface drivers to limit data I/O to word sizes

[Andy Shevchenko]

On Mon, Jul 27, 2015 at 2:37 PM, Michael van der Westhuizen
<michael@smart-africa.com> wrote:
> The commit dd11444327ce ("spi: dw-spi: Convert 16bit accesses to 32bit
> accesses") changed all 16bit accesses in the DW_apb_ssi driver to 32bit.
> This, unfortunately, breaks data register access on picoXcell, where the
> DW IP needs data register accesses to be word accesses (all other
> accesses appear to be OK).
>
> This change introduces a new master variable to allow interface drivers
> to specify that 16bit data transfer I/O is required.  This change also
> introduces the ability to set this variable via device tree bindings in
> the MMIO interface driver.
>
> Before this change, on a picoXcell pc3x3:
>  spi_master spi32766: interrupt_transfer: fifo overrun/underrun
>  m25p80 spi32766.0: error -5 reading 9f
>  m25p80: probe of spi32766.0 failed with error -5
>
> After this change:
>  m25p80 spi32766.0: m25p40 (512 Kbytes)
>
> Fixes: dd11444327ce ("spi: dw-spi: Convert 16bit accesses to 32bit accesses")
> Signed-off-by: Michael van der Westhuizen <michael@smart-africa.com>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

One minor comment below.

> ---
>
> Changes in v2:
>   - Incorporate review feedback from Andy Shevchenko
>     - Rework the DT bindings to accept an I/O register width as a
>       number of bytes rather than using a boolean spefifying the
>       width preference to be 16 bits.
>     - Add data register access wrapper functions and use them when
>       reading and writing the data register.
>
>  drivers/spi/spi-dw-mmio.c |  4 ++++
>  drivers/spi/spi-dw.c      |  4 ++--
>  drivers/spi/spi-dw.h      | 35 +++++++++++++++++++++++++++++++++++
>  3 files changed, 41 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c
> index eb03e12..e76bf72 100644
> --- a/drivers/spi/spi-dw-mmio.c
> +++ b/drivers/spi/spi-dw-mmio.c
> @@ -74,6 +74,10 @@ static int dw_spi_mmio_probe(struct platform_device *pdev)
>
>         dws->max_freq = clk_get_rate(dwsmmio->clk);
>
> +       if (pdev->dev.of_node)

of_property_read_u32() is NULL-aware. Since the option is optional we
may drop the condition.

> +               of_property_read_u32(pdev->dev.of_node, "snps,reg-io-width",

Like Rob said, drop 'snps,' prefix as it is a generic property name.

> +                                    &dws->reg_io_width);
> +
>         num_cs = 4;
>
>         if (pdev->dev.of_node)
> diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
> index 8d67d03..4fbfcdc 100644
> --- a/drivers/spi/spi-dw.c
> +++ b/drivers/spi/spi-dw.c
> @@ -194,7 +194,7 @@ static void dw_writer(struct dw_spi *dws)
>                         else
>                                 txw = *(u16 *)(dws->tx);
>                 }
> -               dw_writel(dws, DW_SPI_DR, txw);
> +               dw_write_io_reg(dws, DW_SPI_DR, txw);
>                 dws->tx += dws->n_bytes;
>         }
>  }
> @@ -205,7 +205,7 @@ static void dw_reader(struct dw_spi *dws)
>         u16 rxw;
>
>         while (max--) {
> -               rxw = dw_readl(dws, DW_SPI_DR);
> +               rxw = dw_read_io_reg(dws, DW_SPI_DR);
>                 /* Care rx only if the transfer's original "rx" is not null */
>                 if (dws->rx_end - dws->len) {
>                         if (dws->n_bytes == 1)
> diff --git a/drivers/spi/spi-dw.h b/drivers/spi/spi-dw.h
> index 6c91391..b75ed32 100644
> --- a/drivers/spi/spi-dw.h
> +++ b/drivers/spi/spi-dw.h
> @@ -109,6 +109,7 @@ struct dw_spi {
>         u32                     fifo_len;       /* depth of the FIFO buffer */
>         u32                     max_freq;       /* max bus freq supported */
>
> +       u32                     reg_io_width;   /* DR I/O width in bytes */
>         u16                     bus_num;
>         u16                     num_cs;         /* supported slave numbers */
>
> @@ -145,11 +146,45 @@ static inline u32 dw_readl(struct dw_spi *dws, u32 offset)
>         return __raw_readl(dws->regs + offset);
>  }
>
> +static inline u16 dw_readw(struct dw_spi *dws, u32 offset)
> +{
> +       return __raw_readw(dws->regs + offset);
> +}
> +
>  static inline void dw_writel(struct dw_spi *dws, u32 offset, u32 val)
>  {
>         __raw_writel(val, dws->regs + offset);
>  }
>
> +static inline void dw_writew(struct dw_spi *dws, u32 offset, u16 val)
> +{
> +       __raw_writew(val, dws->regs + offset);
> +}
> +
> +static inline u32 dw_read_io_reg(struct dw_spi *dws, u32 offset)
> +{
> +       switch (dws->reg_io_width) {
> +       case 2:
> +               return dw_readw(dws, offset);
> +       case 4:
> +       default:
> +               return dw_readl(dws, offset);
> +       }
> +}
> +
> +static inline void dw_write_io_reg(struct dw_spi *dws, u32 offset, u32 val)
> +{
> +       switch (dws->reg_io_width) {
> +       case 2:
> +               dw_writew(dws, offset, val);
> +               break;
> +       case 4:
> +       default:
> +               dw_writel(dws, offset, val);
> +               break;
> +       }
> +}
> +
>  static inline void spi_enable_chip(struct dw_spi *dws, int enable)
>  {
>         dw_writel(dws, DW_SPI_SSIENR, (enable ? 1 : 0));
> --
> 2.1.4
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-spi" in
> the body of a message to majordomo at vger.kernel.org
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-- 
With Best Regards,
Andy Shevchenko