[PATCH v5 0/2] i2c: designware: Add support for a bus clock

[PATCH v5 0/2] i2c: designware: Add support for a bus clock

[Gareth Williams]

The Synopsys I2C Controller has an interface clock that some SoCs 
require to access the registers. This series also details the new clock
property in the bindings documentation.

v5:
 - Code comments and commit messages updated to reference "interface clock"
   instead of "peripheral clock".

v4:
 - Code comments and commit messages updated to reference "peripheral 
   clock"
   instead of "bus clock".

v3:
 - busclk renamed to pclk.
 - Added comment with dw_i2c_dev struct definition describing pclk.
 - Added enable rollback of first clock if second fails to enable.
 - Changed clocks and clock-names sections to use term "peripheral clock"
   (pclk) instead of "bus clock" (busclk) in dt-bindings documentation.

v2:
 - Use new devm_clk_get_optional() function as it simplifies handling when
   the optional clock is not present.

Phil Edworthy (2):
  dt: snps,designware-i2c: Add clock bindings documentation
  i2c: designware: Add support for an interface clock

 .../devicetree/bindings/i2c/i2c-designware.txt         |  9 +++++++++
 drivers/i2c/busses/i2c-designware-common.c             | 18 ++++++++++++++++--
 drivers/i2c/busses/i2c-designware-core.h               |  2 ++
 drivers/i2c/busses/i2c-designware-platdrv.c            |  5 +++++
 4 files changed, 32 insertions(+), 2 deletions(-)

-- 
2.7.4

[PATCH v5 1/2] dt: snps,designware-i2c: Add clock bindings documentation

[Gareth Williams]

From: Phil Edworthy <phil.edworthy@renesas.com>

The driver requires an undocumented clock property, so detail it.
Add documentation for a separate, optional, interface clock.

Signed-off-by: Phil Edworthy <phil.edworthy@renesas.com>
Signed-off-by: Gareth Williams <gareth.williams.jx@renesas.com>
Acked-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Rob Herring <robh@kernel.org>
---
v5:
 - Changed clocks and clock-names sections to use term "interface
   clock" instead of "peripheral clock".
 - Updated commit message to reference "interface clock" instead of
   "peripheral clock".
v4:
 - Updated commit message to reference "peripheral clock" instead of
   "bus clock".
v3:
 - Changed clocks and clock-names sections to use term "peripheral clock"
   (pclk) instead of "bus clock" (busclk).
v2:
 - No changes.
v1:
 - Reviewed-by: Rob Herring <robh@kernel.org>
---
 Documentation/devicetree/bindings/i2c/i2c-designware.txt | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/Documentation/devicetree/bindings/i2c/i2c-designware.txt b/Documentation/devicetree/bindings/i2c/i2c-designware.txt
index 3e4bcc2..aa2c106 100644
--- a/Documentation/devicetree/bindings/i2c/i2c-designware.txt
+++ b/Documentation/devicetree/bindings/i2c/i2c-designware.txt
@@ -6,12 +6,21 @@ Required properties :
                 or "mscc,ocelot-i2c" with "snps,designware-i2c" for fallback
  - reg : Offset and length of the register set for the device
  - interrupts : <IRQ> where IRQ is the interrupt number.
+ - clocks : phandles for the clocks, see the description of clock-names below.
+   The phandle for the "ic_clk" clock is required. The phandle for the "pclk"
+   clock is optional. If a single clock is specified but no clock-name, it is
+   the "ic_clk" clock. If both clocks are listed, the "ic_clk" must be first.
 
 Recommended properties :
 
  - clock-frequency : desired I2C bus clock frequency in Hz.
 
 Optional properties :
+
+ - clock-names : Contains the names of the clocks:
+    "ic_clk", for the core clock used to generate the external I2C clock.
+    "pclk", the interface clock, required for register access.
+
  - reg : for "mscc,ocelot-i2c", a second register set to configure the SDA hold
    time, named ICPU_CFG:TWI_DELAY in the datasheet.
 
-- 
2.7.4

[PATCH v5 2/2] i2c: designware: Add support for an interface clock

[Gareth Williams]

From: Phil Edworthy <phil.edworthy@renesas.com>

The Synopsys I2C Controller has an interface clock, but most SoCs hide
this away. However, on some SoCs you need to explicitly enable the
interface clock in order to access the registers. Therefore, add 
support for an optional interface clock.

Signed-off-by: Phil Edworthy <phil.edworthy@renesas.com>
Signed-off-by: Gareth Williams <gareth.williams.jx@renesas.com>
Acked-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---
v5:
 - Updated comments to reference "interface clock" instead of
   "peripheral clock".
 - Corrected spelling in commit message, changing "explicity" to
   "explicitly".
v4:
 - Updated comments to reference "peripheral clock"
   instead of "bus clock".
 - Added Wolfram's Acked-by
v3:
 - busclk renamed to pclk.
 - Added comment with dw_i2c_dev struct definition describing pclk.
 - Added enable rollback of first clock if second fails to enable.
v2:
 - Use new devm_clk_get_optional() function as it simplifies handling when
   the optional clock is not present.
---
 drivers/i2c/busses/i2c-designware-common.c  | 18 ++++++++++++++++--
 drivers/i2c/busses/i2c-designware-core.h    |  2 ++
 drivers/i2c/busses/i2c-designware-platdrv.c |  5 +++++
 3 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-designware-common.c b/drivers/i2c/busses/i2c-designware-common.c
index a473011..2de7452 100644
--- a/drivers/i2c/busses/i2c-designware-common.c
+++ b/drivers/i2c/busses/i2c-designware-common.c
@@ -251,13 +251,27 @@ unsigned long i2c_dw_clk_rate(struct dw_i2c_dev *dev)
 
 int i2c_dw_prepare_clk(struct dw_i2c_dev *dev, bool prepare)
 {
+	int ret;
+
 	if (IS_ERR(dev->clk))
 		return PTR_ERR(dev->clk);
 
-	if (prepare)
-		return clk_prepare_enable(dev->clk);
+	if (prepare) {
+		/* Optional interface clock */
+		ret = clk_prepare_enable(dev->pclk);
+		if (ret)
+			return ret;
+
+		ret = clk_prepare_enable(dev->clk);
+		if (ret)
+			clk_disable_unprepare(dev->pclk);
+
+		return ret;
+	}
 
 	clk_disable_unprepare(dev->clk);
+	clk_disable_unprepare(dev->pclk);
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(i2c_dw_prepare_clk);
diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
index b4a0b2b..e88c711 100644
--- a/drivers/i2c/busses/i2c-designware-core.h
+++ b/drivers/i2c/busses/i2c-designware-core.h
@@ -177,6 +177,7 @@
  * @base: IO registers pointer
  * @cmd_complete: tx completion indicator
  * @clk: input reference clock
+ * @pclk: clock required to access the registers
  * @slave: represent an I2C slave device
  * @cmd_err: run time hadware error code
  * @msgs: points to an array of messages currently being transferred
@@ -226,6 +227,7 @@ struct dw_i2c_dev {
 	void __iomem		*ext;
 	struct completion	cmd_complete;
 	struct clk		*clk;
+	struct clk		*pclk;
 	struct reset_control	*rst;
 	struct i2c_client		*slave;
 	u32			(*get_clk_rate_khz) (struct dw_i2c_dev *dev);
diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index 9eaac3b..97129f5 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -346,6 +346,11 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
 	else
 		i2c_dw_configure_master(dev);
 
+	/* Optional interface clock */
+	dev->pclk = devm_clk_get_optional(&pdev->dev, "pclk");
+	if (IS_ERR(dev->pclk))
+		return PTR_ERR(dev->pclk);
+
 	dev->clk = devm_clk_get(&pdev->dev, NULL);
 	if (!i2c_dw_prepare_clk(dev, true)) {
 		u64 clk_khz;
-- 
2.7.4

Re: [PATCH v5 2/2] i2c: designware: Add support for an interface clock

[Jarkko Nikula]

On 2/28/19 3:52 PM, Gareth Williams wrote:
> From: Phil Edworthy <phil.edworthy@renesas.com>
> 
> The Synopsys I2C Controller has an interface clock, but most SoCs hide
> this away. However, on some SoCs you need to explicitly enable the
> interface clock in order to access the registers. Therefore, add
> support for an optional interface clock.
> 
> Signed-off-by: Phil Edworthy <phil.edworthy@renesas.com>
> Signed-off-by: Gareth Williams <gareth.williams.jx@renesas.com>
> Acked-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
> ---
> v5:
>   - Updated comments to reference "interface clock" instead of
>     "peripheral clock".
>   - Corrected spelling in commit message, changing "explicity" to
>     "explicitly".
> v4:
>   - Updated comments to reference "peripheral clock"
>     instead of "bus clock".
>   - Added Wolfram's Acked-by
> v3:
>   - busclk renamed to pclk.
>   - Added comment with dw_i2c_dev struct definition describing pclk.
>   - Added enable rollback of first clock if second fails to enable.
> v2:
>   - Use new devm_clk_get_optional() function as it simplifies handling when
>     the optional clock is not present.
> ---
>   drivers/i2c/busses/i2c-designware-common.c  | 18 ++++++++++++++++--
>   drivers/i2c/busses/i2c-designware-core.h    |  2 ++
>   drivers/i2c/busses/i2c-designware-platdrv.c |  5 +++++
>   3 files changed, 23 insertions(+), 2 deletions(-)
> 
Build & boot tested on linux-next that has the required commit
60b8f0ddf1a9 ("clk: Add (devm_)clk_get_optional() functions").

Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Tested-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>

Re: [PATCH v5 1/2] dt: snps,designware-i2c: Add clock bindings documentation

[Jarkko Nikula]

On 2/28/19 3:52 PM, Gareth Williams wrote:
> From: Phil Edworthy <phil.edworthy@renesas.com>
> 
> The driver requires an undocumented clock property, so detail it.
> Add documentation for a separate, optional, interface clock.
> 
> Signed-off-by: Phil Edworthy <phil.edworthy@renesas.com>
> Signed-off-by: Gareth Williams <gareth.williams.jx@renesas.com>
> Acked-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
> Reviewed-by: Rob Herring <robh@kernel.org>
> ---
> v5:
>   - Changed clocks and clock-names sections to use term "interface
>     clock" instead of "peripheral clock".
>   - Updated commit message to reference "interface clock" instead of
>     "peripheral clock".
> v4:
>   - Updated commit message to reference "peripheral clock" instead of
>     "bus clock".
> v3:
>   - Changed clocks and clock-names sections to use term "peripheral clock"
>     (pclk) instead of "bus clock" (busclk).
> v2:
>   - No changes.
> v1:
>   - Reviewed-by: Rob Herring <robh@kernel.org>
> ---
>   Documentation/devicetree/bindings/i2c/i2c-designware.txt | 9 +++++++++
>   1 file changed, 9 insertions(+)
> 
Reviewed-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>

Re: [PATCH v5 1/2] dt: snps,designware-i2c: Add clock bindings documentation

[Wolfram Sang]

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On Thu, Feb 28, 2019 at 01:52:09PM +0000, Gareth Williams wrote:
> From: Phil Edworthy <phil.edworthy@renesas.com>
> 
> The driver requires an undocumented clock property, so detail it.
> Add documentation for a separate, optional, interface clock.
> 
> Signed-off-by: Phil Edworthy <phil.edworthy@renesas.com>
> Signed-off-by: Gareth Williams <gareth.williams.jx@renesas.com>
> Acked-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
> Reviewed-by: Rob Herring <robh@kernel.org>

Applied to for-next, thanks!


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Re: [PATCH v5 2/2] i2c: designware: Add support for an interface clock

[Wolfram Sang]

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On Thu, Feb 28, 2019 at 01:52:10PM +0000, Gareth Williams wrote:
> From: Phil Edworthy <phil.edworthy@renesas.com>
> 
> The Synopsys I2C Controller has an interface clock, but most SoCs hide
> this away. However, on some SoCs you need to explicitly enable the
> interface clock in order to access the registers. Therefore, add 
> support for an optional interface clock.
> 
> Signed-off-by: Phil Edworthy <phil.edworthy@renesas.com>
> Signed-off-by: Gareth Williams <gareth.williams.jx@renesas.com>
> Acked-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

Applied to for-next, thanks!


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