[PATCH v2 1/6] spi: sh-msiof: Improve bindings

[PATCH v2 1/6] spi: sh-msiof: Improve bindings

[Geert Uytterhoeven]

From: Geert Uytterhoeven <geert+renesas-Td1EMuHUCqxL1ZNQvxDV9g@public.gmane.org>

Documentation:
  - Add missing "interrupt-parent", "#address-cells", "#size-cells", and
    "clocks" properties,
  - Add missing default values for "num-cs", "renesas,tx-fifo-size" and
    "renesas,rx-fifo-size",
  - Add a reference to the pinctrl documentation.

Implementation:
  - As "num-cs" is marked optional, provide a sensible default.

Signed-off-by: Geert Uytterhoeven <geert+renesas-Td1EMuHUCqxL1ZNQvxDV9g@public.gmane.org>
Cc: devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
---
v2:
  - As num-cs is marked optional, provide a sensible default

 Documentation/devicetree/bindings/spi/sh-msiof.txt |   24 ++++++++++++++------
 drivers/spi/spi-sh-msiof.c                         |    2 +-
 2 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/Documentation/devicetree/bindings/spi/sh-msiof.txt b/Documentation/devicetree/bindings/spi/sh-msiof.txt
index e6222106ca36..eae3c8c9300e 100644
--- a/Documentation/devicetree/bindings/spi/sh-msiof.txt
+++ b/Documentation/devicetree/bindings/spi/sh-msiof.txt
@@ -1,12 +1,22 @@
 Renesas MSIOF spi controller
 
 Required properties:
-- compatible : 	"renesas,sh-msiof" for SuperH or
-		"renesas,sh-mobile-msiof" for SH Mobile series
-- reg : Offset and length of the register set for the device
-- interrupts : interrupt line used by MSIOF
+- compatible           : "renesas,sh-msiof" for SuperH, or
+			 "renesas,sh-mobile-msiof" for SH Mobile series.
+- reg                  : Offset and length of the register set for the device
+- interrupt-parent     : The phandle for the interrupt controller that
+			 services interrupts for this device
+- interrupts           : Interrupt specifier
+- #address-cells       : Must be <1>
+- #size-cells          : Must be <0>
 
 Optional properties:
-- num-cs		: total number of chip-selects
-- renesas,tx-fifo-size	: Overrides the default tx fifo size given in words
-- renesas,rx-fifo-size	: Overrides the default rx fifo size given in words
+- clocks               : Must contain a reference to the functional clock.
+- num-cs               : Total number of chip-selects (default is 1)
+- renesas,tx-fifo-size : Overrides the default tx fifo size given in words
+			 (default is 64)
+- renesas,rx-fifo-size : Overrides the default rx fifo size given in words
+			 (default is 64)
+
+Pinctrl properties might be needed, too.  See
+Documentation/devicetree/bindings/pinctrl/renesas,*.
diff --git a/drivers/spi/spi-sh-msiof.c b/drivers/spi/spi-sh-msiof.c
index 92515c1ececa..bbe963018e1a 100644
--- a/drivers/spi/spi-sh-msiof.c
+++ b/drivers/spi/spi-sh-msiof.c
@@ -663,7 +663,7 @@ static struct sh_msiof_spi_info *sh_msiof_spi_parse_dt(struct device *dev)
 {
 	struct sh_msiof_spi_info *info;
 	struct device_node *np = dev->of_node;
-	u32 num_cs = 0;
+	u32 num_cs = 1;
 
 	info = devm_kzalloc(dev, sizeof(struct sh_msiof_spi_info), GFP_KERNEL);
 	if (!info) {
-- 
1.7.9.5

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[PATCH v2 3/6] spi: sh-msiof: Add support for R-Car H2 and M2

[Geert Uytterhoeven]

From: Geert Uytterhoeven <geert+renesas@linux-m68k.org>

Add support for the MSIOF variant in the R-Car H2 (r8a7790) and M2
(r8a7791) SoCs.

Binding documentation:
  - Add future-proof "renesas,msiof-<soctype>" compatible values,
  - The default for "renesas,rx-fifo-size" is 256 on R-Car H2 and M2,
  - "renesas,tx-fifo-size" and "renesas,rx-fifo-size" are deprecated for
    soctype-specific bindings,
  - Add example bindings.

Implementation:
  - MSIOF on R-Car H2 and M2 requires the transmission of dummy data if
    data is being received only (cfr. "Set SICTR.TSCKE to 1" and "Write
    dummy transmission data to SITFDR" in paragraph "Transmit and Receive
    Procedures" of the Hardware User's Manual).
  - As RX depends on TX, MSIOF on R-Car H2 and M2 also lacks the RSCR
    register (Receive Clock Select Register), and some bits in the RMDR1
    (Receive Mode Register 1) and TMDR2 (Transmit Mode Register 2)
    registers.
  - Use the recently introduced SPI_MASTER_MUST_TX flag to enable support
    for dummy transmission in the SPI core, and to differentiate from other
    MSIOF implementations in code paths that need this.
  - New DT compatible values ("renesas,msiof-r8a7790" and
    "renesas,msiof-r8a7791") are added, as well as new platform device
    names ("spi_r8a7790_msiof" and "spi_r8a7791_msiof").
  - The default RX FIFO size is 256 words on R-Car H2 and M2.

This is loosely based on a set of patches from Takashi Yoshii
<takasi-y@ops.dti.ne.jp>.

Signed-off-by: Geert Uytterhoeven <geert+renesas@linux-m68k.org>
Cc: Takashi Yoshii <takasi-y@ops.dti.ne.jp>
Cc: devicetree@vger.kernel.org
---
v2:
  - Rebased on top of new "spi: sh-msiof: Move default FIFO sizes to device
    ID data",
  - The default RX FIFO size is 256 words on R-Car H2 and M2,
  - Deprecated overriding the FIFO size,
  - Synced DT example with node from real DTS.

 Documentation/devicetree/bindings/spi/sh-msiof.txt |   23 ++++++++++++++++++--
 drivers/spi/spi-sh-msiof.c                         |   23 +++++++++++++++++---
 2 files changed, 41 insertions(+), 5 deletions(-)

diff --git a/Documentation/devicetree/bindings/spi/sh-msiof.txt b/Documentation/devicetree/bindings/spi/sh-msiof.txt
index eae3c8c9300e..1f0cb33763a1 100644
--- a/Documentation/devicetree/bindings/spi/sh-msiof.txt
+++ b/Documentation/devicetree/bindings/spi/sh-msiof.txt
@@ -1,8 +1,13 @@
 Renesas MSIOF spi controller
 
 Required properties:
-- compatible           : "renesas,sh-msiof" for SuperH, or
+- compatible           : "renesas,msiof-<soctype>" for SoCs,
+			 "renesas,sh-msiof" for SuperH, or
 			 "renesas,sh-mobile-msiof" for SH Mobile series.
+			 Examples with soctypes are:
+			 "renesas,msiof-sh7724" (SH)
+			 "renesas,msiof-r8a7790" (R-Car H2)
+			 "renesas,msiof-r8a7791" (R-Car M2)
 - reg                  : Offset and length of the register set for the device
 - interrupt-parent     : The phandle for the interrupt controller that
 			 services interrupts for this device
@@ -13,10 +18,24 @@ Required properties:
 Optional properties:
 - clocks               : Must contain a reference to the functional clock.
 - num-cs               : Total number of chip-selects (default is 1)
+
+Optional properties, deprecated for soctype-specific bindings:
 - renesas,tx-fifo-size : Overrides the default tx fifo size given in words
 			 (default is 64)
 - renesas,rx-fifo-size : Overrides the default rx fifo size given in words
-			 (default is 64)
+			 (default is 64, or 256 on R-Car H2 and M2)
 
 Pinctrl properties might be needed, too.  See
 Documentation/devicetree/bindings/pinctrl/renesas,*.
+
+Example:
+
+	msiof0: spi@e6e20000 {
+		compatible = "renesas,msiof-r8a7791";
+		reg = <0 0xe6e20000 0 0x0064>;
+		interrupts = <0 156 IRQ_TYPE_LEVEL_HIGH>;
+		clocks = <&mstp0_clks R8A7791_CLK_MSIOF0>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+		status = "disabled";
+	};
diff --git a/drivers/spi/spi-sh-msiof.c b/drivers/spi/spi-sh-msiof.c
index bf389184924d..3baef2bacaed 100644
--- a/drivers/spi/spi-sh-msiof.c
+++ b/drivers/spi/spi-sh-msiof.c
@@ -34,6 +34,7 @@
 struct sh_msiof_chipdata {
 	u16 tx_fifo_size;
 	u16 rx_fifo_size;
+	u16 master_flags;
 };
 
 struct sh_msiof_spi_priv {
@@ -214,7 +215,8 @@ static void sh_msiof_spi_set_clk_regs(struct sh_msiof_spi_priv *p,
 	k = min_t(int, k, ARRAY_SIZE(sh_msiof_spi_clk_table) - 1);
 
 	sh_msiof_write(p, TSCR, sh_msiof_spi_clk_table[k].scr);
-	sh_msiof_write(p, RSCR, sh_msiof_spi_clk_table[k].scr);
+	if (!(p->chipdata->master_flags & SPI_MASTER_MUST_TX))
+		sh_msiof_write(p, RSCR, sh_msiof_spi_clk_table[k].scr);
 }
 
 static void sh_msiof_spi_set_pin_regs(struct sh_msiof_spi_priv *p,
@@ -237,6 +239,10 @@ static void sh_msiof_spi_set_pin_regs(struct sh_msiof_spi_priv *p,
 	tmp |= !cs_high << MDR1_SYNCAC_SHIFT;
 	tmp |= lsb_first << MDR1_BITLSB_SHIFT;
 	sh_msiof_write(p, TMDR1, tmp | MDR1_TRMD | TMDR1_PCON);
+	if (p->chipdata->master_flags & SPI_MASTER_MUST_TX) {
+		/* These bits are reserved if RX needs TX */
+		tmp &= ~0x0000ffff;
+	}
 	sh_msiof_write(p, RMDR1, tmp);
 
 	tmp = 0;
@@ -257,7 +263,7 @@ static void sh_msiof_spi_set_mode_regs(struct sh_msiof_spi_priv *p,
 {
 	u32 dr2 = MDR2_BITLEN1(bits) | MDR2_WDLEN1(words);
 
-	if (tx_buf)
+	if (tx_buf || (p->chipdata->master_flags & SPI_MASTER_MUST_TX))
 		sh_msiof_write(p, TMDR2, dr2);
 	else
 		sh_msiof_write(p, TMDR2, dr2 | MDR2_GRPMASK1);
@@ -666,11 +672,20 @@ static u32 sh_msiof_spi_txrx_word(struct spi_device *spi, unsigned nsecs,
 static const struct sh_msiof_chipdata sh_data = {
 	.tx_fifo_size = 64,
 	.rx_fifo_size = 64,
+	.master_flags = 0,
+};
+
+static const struct sh_msiof_chipdata r8a779x_data = {
+	.tx_fifo_size = 64,
+	.rx_fifo_size = 256,
+	.master_flags = SPI_MASTER_MUST_TX,
 };
 
 static const struct of_device_id sh_msiof_match[] = {
 	{ .compatible = "renesas,sh-msiof",        .data = &sh_data },
 	{ .compatible = "renesas,sh-mobile-msiof", .data = &sh_data },
+	{ .compatible = "renesas,msiof-r8a7790",   .data = &r8a779x_data },
+	{ .compatible = "renesas,msiof-r8a7791",   .data = &r8a779x_data },
 	{},
 };
 MODULE_DEVICE_TABLE(of, sh_msiof_match);
@@ -789,7 +804,7 @@ static int sh_msiof_spi_probe(struct platform_device *pdev)
 	/* init master and bitbang code */
 	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
 	master->mode_bits |= SPI_LSB_FIRST | SPI_3WIRE;
-	master->flags = 0;
+	master->flags = p->chipdata->master_flags;
 	master->bus_num = pdev->id;
 	master->dev.of_node = pdev->dev.of_node;
 	master->num_chipselect = p->info->num_chipselect;
@@ -832,6 +847,8 @@ static int sh_msiof_spi_remove(struct platform_device *pdev)
 
 static struct platform_device_id spi_driver_ids[] = {
 	{ "spi_sh_msiof",	(kernel_ulong_t)&sh_data },
+	{ "spi_r8a7790_msiof",	(kernel_ulong_t)&r8a779x_data },
+	{ "spi_r8a7791_msiof",	(kernel_ulong_t)&r8a779x_data },
 	{},
 };
 MODULE_DEVICE_TABLE(platform, spi_driver_ids);
-- 
1.7.9.5

Re: [PATCH v2 3/6] spi: sh-msiof: Add support for R-Car H2 and M2

[Laurent Pinchart]

Hi Geert,

Thank you for the patch.

Overall the series is great. I ran some time ago into issues with CCF due to 
the driver use of spi-bitbang, I'm happy to see this being fixed, thanks a 
lot. I have one small comment below though.

On Tuesday 25 February 2014 11:21:10 Geert Uytterhoeven wrote:
> From: Geert Uytterhoeven <geert+renesas@linux-m68k.org>
> 
> Add support for the MSIOF variant in the R-Car H2 (r8a7790) and M2
> (r8a7791) SoCs.
> 
> Binding documentation:
>   - Add future-proof "renesas,msiof-<soctype>" compatible values,
>   - The default for "renesas,rx-fifo-size" is 256 on R-Car H2 and M2,
>   - "renesas,tx-fifo-size" and "renesas,rx-fifo-size" are deprecated for
>     soctype-specific bindings,
>   - Add example bindings.
> 
> Implementation:
>   - MSIOF on R-Car H2 and M2 requires the transmission of dummy data if
>     data is being received only (cfr. "Set SICTR.TSCKE to 1" and "Write
>     dummy transmission data to SITFDR" in paragraph "Transmit and Receive
>     Procedures" of the Hardware User's Manual).
>   - As RX depends on TX, MSIOF on R-Car H2 and M2 also lacks the RSCR
>     register (Receive Clock Select Register), and some bits in the RMDR1
>     (Receive Mode Register 1) and TMDR2 (Transmit Mode Register 2)
>     registers.
>   - Use the recently introduced SPI_MASTER_MUST_TX flag to enable support
>     for dummy transmission in the SPI core, and to differentiate from other
>     MSIOF implementations in code paths that need this.
>   - New DT compatible values ("renesas,msiof-r8a7790" and
>     "renesas,msiof-r8a7791") are added, as well as new platform device
>     names ("spi_r8a7790_msiof" and "spi_r8a7791_msiof").
>   - The default RX FIFO size is 256 words on R-Car H2 and M2.
> 
> This is loosely based on a set of patches from Takashi Yoshii
> <takasi-y@ops.dti.ne.jp>.
> 
> Signed-off-by: Geert Uytterhoeven <geert+renesas@linux-m68k.org>
> Cc: Takashi Yoshii <takasi-y@ops.dti.ne.jp>
> Cc: devicetree@vger.kernel.org
> ---
> v2:
>   - Rebased on top of new "spi: sh-msiof: Move default FIFO sizes to device
>     ID data",
>   - The default RX FIFO size is 256 words on R-Car H2 and M2,
>   - Deprecated overriding the FIFO size,
>   - Synced DT example with node from real DTS.
> 
>  Documentation/devicetree/bindings/spi/sh-msiof.txt |   23 +++++++++++++++--
>  drivers/spi/spi-sh-msiof.c                         |   23 ++++++++++++++---
>  2 files changed, 41 insertions(+), 5 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/spi/sh-msiof.txt
> b/Documentation/devicetree/bindings/spi/sh-msiof.txt index
> eae3c8c9300e..1f0cb33763a1 100644
> --- a/Documentation/devicetree/bindings/spi/sh-msiof.txt
> +++ b/Documentation/devicetree/bindings/spi/sh-msiof.txt
> @@ -1,8 +1,13 @@
>  Renesas MSIOF spi controller
> 
>  Required properties:
> -- compatible           : "renesas,sh-msiof" for SuperH, or
> +- compatible           : "renesas,msiof-<soctype>" for SoCs,
> +			 "renesas,sh-msiof" for SuperH, or
>  			 "renesas,sh-mobile-msiof" for SH Mobile series.
> +			 Examples with soctypes are:
> +			 "renesas,msiof-sh7724" (SH)

Given that the driver doesn't handle the "renesas,msiof-sh7724" compatible 
string this might not be a good example. Furthermore SuperH doesn't have DT 
support. I would thus drop the "renesas,sh-msiof" compatible string from patch 
1/6 and wouldn't mention sh7724 here. I very much doubt that someone would 
have developed DT support for SuperH on the side and shipped products that 
would be broken by this change :-)

> +			 "renesas,msiof-r8a7790" (R-Car H2)
> +			 "renesas,msiof-r8a7791" (R-Car M2)
>  - reg                  : Offset and length of the register set for the
> device - interrupt-parent     : The phandle for the interrupt controller
> that services interrupts for this device
> @@ -13,10 +18,24 @@ Required properties:
>  Optional properties:
>  - clocks               : Must contain a reference to the functional clock.
>  - num-cs               : Total number of chip-selects (default is 1)
> +
> +Optional properties, deprecated for soctype-specific bindings:
>  - renesas,tx-fifo-size : Overrides the default tx fifo size given in words
>  			 (default is 64)
>  - renesas,rx-fifo-size : Overrides the default rx fifo size given in words
> -			 (default is 64)
> +			 (default is 64, or 256 on R-Car H2 and M2)
> 
>  Pinctrl properties might be needed, too.  See
>  Documentation/devicetree/bindings/pinctrl/renesas,*.
> +
> +Example:
> +
> +	msiof0: spi@e6e20000 {
> +		compatible = "renesas,msiof-r8a7791";
> +		reg = <0 0xe6e20000 0 0x0064>;
> +		interrupts = <0 156 IRQ_TYPE_LEVEL_HIGH>;
> +		clocks = <&mstp0_clks R8A7791_CLK_MSIOF0>;
> +		#address-cells = <1>;
> +		#size-cells = <0>;
> +		status = "disabled";
> +	};
> diff --git a/drivers/spi/spi-sh-msiof.c b/drivers/spi/spi-sh-msiof.c
> index bf389184924d..3baef2bacaed 100644
> --- a/drivers/spi/spi-sh-msiof.c
> +++ b/drivers/spi/spi-sh-msiof.c
> @@ -34,6 +34,7 @@
>  struct sh_msiof_chipdata {
>  	u16 tx_fifo_size;
>  	u16 rx_fifo_size;
> +	u16 master_flags;
>  };
> 
>  struct sh_msiof_spi_priv {
> @@ -214,7 +215,8 @@ static void sh_msiof_spi_set_clk_regs(struct
> sh_msiof_spi_priv *p, k = min_t(int, k, ARRAY_SIZE(sh_msiof_spi_clk_table)
> - 1);
> 
>  	sh_msiof_write(p, TSCR, sh_msiof_spi_clk_table[k].scr);
> -	sh_msiof_write(p, RSCR, sh_msiof_spi_clk_table[k].scr);
> +	if (!(p->chipdata->master_flags & SPI_MASTER_MUST_TX))
> +		sh_msiof_write(p, RSCR, sh_msiof_spi_clk_table[k].scr);
>  }
> 
>  static void sh_msiof_spi_set_pin_regs(struct sh_msiof_spi_priv *p,
> @@ -237,6 +239,10 @@ static void sh_msiof_spi_set_pin_regs(struct
> sh_msiof_spi_priv *p, tmp |= !cs_high << MDR1_SYNCAC_SHIFT;
>  	tmp |= lsb_first << MDR1_BITLSB_SHIFT;
>  	sh_msiof_write(p, TMDR1, tmp | MDR1_TRMD | TMDR1_PCON);
> +	if (p->chipdata->master_flags & SPI_MASTER_MUST_TX) {
> +		/* These bits are reserved if RX needs TX */
> +		tmp &= ~0x0000ffff;
> +	}
>  	sh_msiof_write(p, RMDR1, tmp);
> 
>  	tmp = 0;
> @@ -257,7 +263,7 @@ static void sh_msiof_spi_set_mode_regs(struct
> sh_msiof_spi_priv *p, {
>  	u32 dr2 = MDR2_BITLEN1(bits) | MDR2_WDLEN1(words);
> 
> -	if (tx_buf)
> +	if (tx_buf || (p->chipdata->master_flags & SPI_MASTER_MUST_TX))
>  		sh_msiof_write(p, TMDR2, dr2);
>  	else
>  		sh_msiof_write(p, TMDR2, dr2 | MDR2_GRPMASK1);
> @@ -666,11 +672,20 @@ static u32 sh_msiof_spi_txrx_word(struct spi_device
> *spi, unsigned nsecs, static const struct sh_msiof_chipdata sh_data = {
>  	.tx_fifo_size = 64,
>  	.rx_fifo_size = 64,
> +	.master_flags = 0,
> +};
> +
> +static const struct sh_msiof_chipdata r8a779x_data = {
> +	.tx_fifo_size = 64,
> +	.rx_fifo_size = 256,
> +	.master_flags = SPI_MASTER_MUST_TX,
>  };
> 
>  static const struct of_device_id sh_msiof_match[] = {
>  	{ .compatible = "renesas,sh-msiof",        .data = &sh_data },
>  	{ .compatible = "renesas,sh-mobile-msiof", .data = &sh_data },
> +	{ .compatible = "renesas,msiof-r8a7790",   .data = &r8a779x_data },
> +	{ .compatible = "renesas,msiof-r8a7791",   .data = &r8a779x_data },
>  	{},
>  };
>  MODULE_DEVICE_TABLE(of, sh_msiof_match);
> @@ -789,7 +804,7 @@ static int sh_msiof_spi_probe(struct platform_device
> *pdev) /* init master and bitbang code */
>  	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
>  	master->mode_bits |= SPI_LSB_FIRST | SPI_3WIRE;
> -	master->flags = 0;
> +	master->flags = p->chipdata->master_flags;
>  	master->bus_num = pdev->id;
>  	master->dev.of_node = pdev->dev.of_node;
>  	master->num_chipselect = p->info->num_chipselect;
> @@ -832,6 +847,8 @@ static int sh_msiof_spi_remove(struct platform_device
> *pdev)
> 
>  static struct platform_device_id spi_driver_ids[] = {
>  	{ "spi_sh_msiof",	(kernel_ulong_t)&sh_data },
> +	{ "spi_r8a7790_msiof",	(kernel_ulong_t)&r8a779x_data },
> +	{ "spi_r8a7791_msiof",	(kernel_ulong_t)&r8a779x_data },
>  	{},
>  };
>  MODULE_DEVICE_TABLE(platform, spi_driver_ids);

-- 
Regards,

Laurent Pinchart

Re: [PATCH v2 3/6] spi: sh-msiof: Add support for R-Car H2 and M2

[Geert Uytterhoeven]

Hi Laurent,

On Wed, Feb 26, 2014 at 11:16 PM, Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
>> diff --git a/Documentation/devicetree/bindings/spi/sh-msiof.txt
>> b/Documentation/devicetree/bindings/spi/sh-msiof.txt index
>> eae3c8c9300e..1f0cb33763a1 100644
>> --- a/Documentation/devicetree/bindings/spi/sh-msiof.txt
>> +++ b/Documentation/devicetree/bindings/spi/sh-msiof.txt
>> @@ -1,8 +1,13 @@
>>  Renesas MSIOF spi controller
>>
>>  Required properties:
>> -- compatible           : "renesas,sh-msiof" for SuperH, or
>> +- compatible           : "renesas,msiof-<soctype>" for SoCs,
>> +                      "renesas,sh-msiof" for SuperH, or
>>                        "renesas,sh-mobile-msiof" for SH Mobile series.
>> +                      Examples with soctypes are:
>> +                      "renesas,msiof-sh7724" (SH)
>
> Given that the driver doesn't handle the "renesas,msiof-sh7724" compatible
> string this might not be a good example. Furthermore SuperH doesn't have DT
> support. I would thus drop the "renesas,sh-msiof" compatible string from patch
> 1/6 and wouldn't mention sh7724 here. I very much doubt that someone would
> have developed DT support for SuperH on the side and shipped products that
> would be broken by this change :-)

Right. Originally I had 'or "renesas,sh-msiof" as fallback', but the fallbacks
have been dropped, so it indeed won't work with just "renesas,msiof-sh7724".
I'll fix that.

Thanks for your review!

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH v2 3/6] spi: sh-msiof: Add support for R-Car H2 and M2

[Geert Uytterhoeven]

On Wed, Feb 26, 2014 at 11:16 PM, Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
>> diff --git a/Documentation/devicetree/bindings/spi/sh-msiof.txt
>> b/Documentation/devicetree/bindings/spi/sh-msiof.txt index
>> eae3c8c9300e..1f0cb33763a1 100644
>> --- a/Documentation/devicetree/bindings/spi/sh-msiof.txt
>> +++ b/Documentation/devicetree/bindings/spi/sh-msiof.txt
>> @@ -1,8 +1,13 @@
>>  Renesas MSIOF spi controller
>>
>>  Required properties:
>> -- compatible           : "renesas,sh-msiof" for SuperH, or
>> +- compatible           : "renesas,msiof-<soctype>" for SoCs,
>> +                      "renesas,sh-msiof" for SuperH, or
>>                        "renesas,sh-mobile-msiof" for SH Mobile series.
>> +                      Examples with soctypes are:
>> +                      "renesas,msiof-sh7724" (SH)
>
> Given that the driver doesn't handle the "renesas,msiof-sh7724" compatible
> string this might not be a good example. Furthermore SuperH doesn't have DT
> support. I would thus drop the "renesas,sh-msiof" compatible string from patch
> 1/6 and wouldn't mention sh7724 here. I very much doubt that someone would
> have developed DT support for SuperH on the side and shipped products that
> would be broken by this change :-)

Upon reading your comment again: do you suggest to also remove the plain
"renesas,sh-msiof"? That one was present before, since DT support was added
to the driver in

commit cf9c86efecf9510e62388fd174cf607671c59fa3
Author: Bastian Hecht <hechtb@gmail.com>
Date:   Wed Dec 12 12:54:48 2012 +0100

    spi/sh-msiof: Add device tree parsing to driver

    This adds the capability to retrieve setup data from the device tree
    node. The usage of platform data is still available.

    Signed-off-by: Bastian Hecht <hechtb+renesas@gmail.com>
    Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

So I prefer not to remove any pre-existing compatible values.
Do you agree?

Thanks!

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH v2 3/6] spi: sh-msiof: Add support for R-Car H2 and M2

[Laurent Pinchart]

Hi Geert,

On Thursday 27 February 2014 09:39:54 Geert Uytterhoeven wrote:
> On Wed, Feb 26, 2014 at 11:16 PM, Laurent Pinchart wrote:
> >> diff --git a/Documentation/devicetree/bindings/spi/sh-msiof.txt
> >> b/Documentation/devicetree/bindings/spi/sh-msiof.txt index
> >> eae3c8c9300e..1f0cb33763a1 100644
> >> --- a/Documentation/devicetree/bindings/spi/sh-msiof.txt
> >> +++ b/Documentation/devicetree/bindings/spi/sh-msiof.txt
> >> @@ -1,8 +1,13 @@
> >> 
> >>  Renesas MSIOF spi controller
> >> 
> >>  Required properties:
> >> -- compatible           : "renesas,sh-msiof" for SuperH, or
> >> +- compatible           : "renesas,msiof-<soctype>" for SoCs,
> >> +                      "renesas,sh-msiof" for SuperH, or
> >>                        "renesas,sh-mobile-msiof" for SH Mobile series.
> >> +                      Examples with soctypes are:
> >> +                      "renesas,msiof-sh7724" (SH)
> > 
> > Given that the driver doesn't handle the "renesas,msiof-sh7724" compatible
> > string this might not be a good example. Furthermore SuperH doesn't have
> > DT support. I would thus drop the "renesas,sh-msiof" compatible string
> > from patch 1/6 and wouldn't mention sh7724 here. I very much doubt that
> > someone would have developed DT support for SuperH on the side and
> > shipped products that would be broken by this change :-)
> 
> Upon reading your comment again: do you suggest to also remove the plain
> "renesas,sh-msiof"? That one was present before, since DT support was added
> to the driver in
> 
> commit cf9c86efecf9510e62388fd174cf607671c59fa3
> Author: Bastian Hecht <hechtb-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> Date:   Wed Dec 12 12:54:48 2012 +0100
> 
>     spi/sh-msiof: Add device tree parsing to driver
> 
>     This adds the capability to retrieve setup data from the device tree
>     node. The usage of platform data is still available.
> 
>     Signed-off-by: Bastian Hecht <hechtb+renesas-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>     Signed-off-by: Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>
> 
> So I prefer not to remove any pre-existing compatible values.
> Do you agree?

I'd like to remove it (in a separate patch) if we can. The reason is that 
keeping the DT ABI both forward- and backward-compatible is pretty painful 
enough without having to care about compatibility strings that have no user. 
I'd rather work on adding DT support for SuperH MSIOF later when we'll have a 
platform we can test it on, instead of trying to guess now what the needs will 
be, get users later and realize even later on that we made a mistake that we 
can't fix because those users will have DT binaries in the wild. Every 
unneeded bit of DT bindings that we keep in the kernel is one potential 
problem for future binary compatibility.

-- 
Regards,

Laurent Pinchart

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Re: [PATCH v2 3/6] spi: sh-msiof: Add support for R-Car H2 and M2

[Geert Uytterhoeven]

On Thu, Feb 27, 2014 at 11:41 AM, Laurent Pinchart
<laurent.pinchart-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org> wrote:
>> >> -- compatible           : "renesas,sh-msiof" for SuperH, or
>> >> +- compatible           : "renesas,msiof-<soctype>" for SoCs,
>> >> +                      "renesas,sh-msiof" for SuperH, or
>> >>                        "renesas,sh-mobile-msiof" for SH Mobile series.
>> >> +                      Examples with soctypes are:
>> >> +                      "renesas,msiof-sh7724" (SH)
>> >
>> > Given that the driver doesn't handle the "renesas,msiof-sh7724" compatible
>> > string this might not be a good example. Furthermore SuperH doesn't have
>> > DT support. I would thus drop the "renesas,sh-msiof" compatible string
>> > from patch 1/6 and wouldn't mention sh7724 here. I very much doubt that
>> > someone would have developed DT support for SuperH on the side and
>> > shipped products that would be broken by this change :-)
>>
>> Upon reading your comment again: do you suggest to also remove the plain
>> "renesas,sh-msiof"? That one was present before, since DT support was added
>> to the driver in
>>
>> commit cf9c86efecf9510e62388fd174cf607671c59fa3
>> Author: Bastian Hecht <hechtb-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>> Date:   Wed Dec 12 12:54:48 2012 +0100
>>
>>     spi/sh-msiof: Add device tree parsing to driver
>>
>>     This adds the capability to retrieve setup data from the device tree
>>     node. The usage of platform data is still available.
>>
>>     Signed-off-by: Bastian Hecht <hechtb+renesas-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>>     Signed-off-by: Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>
>>
>> So I prefer not to remove any pre-existing compatible values.
>> Do you agree?
>
> I'd like to remove it (in a separate patch) if we can. The reason is that
> keeping the DT ABI both forward- and backward-compatible is pretty painful
> enough without having to care about compatibility strings that have no user.
> I'd rather work on adding DT support for SuperH MSIOF later when we'll have a
> platform we can test it on, instead of trying to guess now what the needs will
> be, get users later and realize even later on that we made a mistake that we
> can't fix because those users will have DT binaries in the wild. Every
> unneeded bit of DT bindings that we keep in the kernel is one potential
> problem for future binary compatibility.

I agree about the complexity of keeping the DT ABI forward- and
backward-compatible.

However, in this case I don't think it hurts that much to just keep it:
  - DT compatible values and platform device names are kept in sync
    through a pointer to the same struct sh_msiof_chipdata, so there's
    not much maintenance needed.
  - DT compatible "renesas,sh-msiof" means exactly the same as
    the "spi_sh_msiof" platform device name, which is currently in use.

So even if SuperH never moves to DT, we have to keep support for that
specific MSIOF implementation, unless we drop the platform device version,
too (Hmm, maybe that's what you're alluding to ;-)

And if we remove "renesas,sh-msiof", we should probably remove
"renesas,sh-mobile-msiof", too, as there are no current users, and it also
assumes the same MSIOF implementation?

Bastian: What was your real plan with "renesas,sh-msiof" and
"renesas,sh-mobile-msiof"?

Gr{oetje,eeting}s,

                        Geert

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

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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Re: [PATCH v2 3/6] spi: sh-msiof: Add support for R-Car H2 and M2

[Laurent Pinchart]

Hi Geert,

On Thursday 27 February 2014 12:09:52 Geert Uytterhoeven wrote:
> On Thu, Feb 27, 2014 at 11:41 AM, Laurent Pinchart wrote:
> >> >> -- compatible           : "renesas,sh-msiof" for SuperH, or
> >> >> +- compatible           : "renesas,msiof-<soctype>" for SoCs,
> >> >> +                      "renesas,sh-msiof" for SuperH, or
> >> >>                        "renesas,sh-mobile-msiof" for SH Mobile series.
> >> >> +                      Examples with soctypes are:
> >> >> +                      "renesas,msiof-sh7724" (SH)
> >> > 
> >> > Given that the driver doesn't handle the "renesas,msiof-sh7724"
> >> > compatible string this might not be a good example. Furthermore SuperH
> >> > doesn't have DT support. I would thus drop the "renesas,sh-msiof"
> >> > compatible string from patch 1/6 and wouldn't mention sh7724 here. I
> >> > very much doubt that someone would have developed DT support for SuperH
> >> > on the side and shipped products that would be broken by this change
> >> > :-)
> >> 
> >> Upon reading your comment again: do you suggest to also remove the plain
> >> "renesas,sh-msiof"? That one was present before, since DT support was
> >> added to the driver in
> >> 
> >> commit cf9c86efecf9510e62388fd174cf607671c59fa3
> >> Author: Bastian Hecht <hechtb-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> >> Date:   Wed Dec 12 12:54:48 2012 +0100
> >> 
> >>     spi/sh-msiof: Add device tree parsing to driver
> >>     
> >>     This adds the capability to retrieve setup data from the device tree
> >>     node. The usage of platform data is still available.
> >>     
> >>     Signed-off-by: Bastian Hecht <hechtb+renesas-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> >>     Signed-off-by: Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>
> >> 
> >> So I prefer not to remove any pre-existing compatible values.
> >> Do you agree?
> > 
> > I'd like to remove it (in a separate patch) if we can. The reason is that
> > keeping the DT ABI both forward- and backward-compatible is pretty painful
> > enough without having to care about compatibility strings that have no
> > user. I'd rather work on adding DT support for SuperH MSIOF later when
> > we'll have a platform we can test it on, instead of trying to guess now
> > what the needs will be, get users later and realize even later on that we
> > made a mistake that we can't fix because those users will have DT
> > binaries in the wild. Every unneeded bit of DT bindings that we keep in
> > the kernel is one potential problem for future binary compatibility.
> 
> I agree about the complexity of keeping the DT ABI forward- and
> backward-compatible.
> 
> However, in this case I don't think it hurts that much to just keep it:
>   - DT compatible values and platform device names are kept in sync
>     through a pointer to the same struct sh_msiof_chipdata, so there's
>     not much maintenance needed.
>   - DT compatible "renesas,sh-msiof" means exactly the same as
>     the "spi_sh_msiof" platform device name, which is currently in use.
> 
> So even if SuperH never moves to DT, we have to keep support for that
> specific MSIOF implementation, unless we drop the platform device version,
> too (Hmm, maybe that's what you're alluding to ;-)

Of course, I'm not trying to get support for SuperH dropped, I'm sure someone 
would realize and complain before the end of the century ;-)

> And if we remove "renesas,sh-msiof", we should probably remove
> "renesas,sh-mobile-msiof", too, as there are no current users, and it also
> assumes the same MSIOF implementation?

I'm not too familiar with the MSIOF hardware, can "renesas,sh-mobile-msiof" be 
used as a fallback for the currently support ARM SoCs ?

> Bastian: What was your real plan with "renesas,sh-msiof" and
> "renesas,sh-mobile-msiof"?

-- 
Regards,

Laurent Pinchart

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Re: [PATCH v2 3/6] spi: sh-msiof: Add support for R-Car H2 and M2

[Geert Uytterhoeven]

Hi Laurent,

On Fri, Feb 28, 2014 at 12:02 AM, Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
>> And if we remove "renesas,sh-msiof", we should probably remove
>> "renesas,sh-mobile-msiof", too, as there are no current users, and it also
>> assumes the same MSIOF implementation?
>
> I'm not too familiar with the MSIOF hardware, can "renesas,sh-mobile-msiof" be
> used as a fallback for the currently support ARM SoCs ?

r8a73a4/APE6: No
r8a7740/A1: Maybe (not 100% clear to me from the datasheet)
r8a7790/R-Car H2: No
r8a7791/R-Car M2: No
sh7372/AP4: No information
sh73a0/AG5: No information

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds