[PATCH 1/2] i2c: designware: device tree bindings for i2c speed mode

[PATCH 1/2] i2c: designware: device tree bindings for i2c speed mode

[atull]

From: Alan Tull <atull@opensource.altera.com>

Add "speed-mode" Device Tree property to select between
standard and fast i2c mode.  Previously, driver was hardwired
as fast mode.  Default to fast mode if property is not
present.

Signed-off-by: Alan Tull <atull@opensource.altera.com>
---
 .../devicetree/bindings/i2c/i2c-designware.txt     |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/devicetree/bindings/i2c/i2c-designware.txt b/Documentation/devicetree/bindings/i2c/i2c-designware.txt
index 5199b0c..0e4cd21 100644
--- a/Documentation/devicetree/bindings/i2c/i2c-designware.txt
+++ b/Documentation/devicetree/bindings/i2c/i2c-designware.txt
@@ -9,6 +9,8 @@ Required properties :
 Recommended properties :
 
  - clock-frequency : desired I2C bus clock frequency in Hz.
+ - speed-mode      : 0 = standard (0 - 100Kb/s)
+                   : 1 = fast (<= 400Kb/s) <== default
 
 Optional properties :
  - i2c-sda-hold-time-ns : should contain the SDA hold time in nanoseconds.
@@ -29,6 +31,7 @@ Example :
 		reg = <0xf0000 0x1000>;
 		interrupts = <11>;
 		clock-frequency = <400000>;
+		speed-mode = <0>;
 	};
 
 	i2c@1120000 {
-- 
1.7.9.5

[PATCH 2/2] i2c: designware: add speed mode device tree setting

[atull]

From: Alan Tull <atull@opensource.altera.com>

Add "speed-mode" Device Tree property to select between
standard and fast i2c mode.  Previously, driver was hardwired
as fast mode.  Default to fast mode if property is not
present.

Signed-off-by: Alan Tull <atull@opensource.altera.com>
---
 drivers/i2c/busses/i2c-designware-platdrv.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index bc87733..3fdc775 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -122,7 +122,7 @@ static int dw_i2c_probe(struct platform_device *pdev)
 	struct dw_i2c_dev *dev;
 	struct i2c_adapter *adap;
 	struct resource *mem;
-	int irq, r;
+	int irq, r, speed_prop, ret, speed = DW_IC_CON_SPEED_FAST;
 
 	irq = platform_get_irq(pdev, 0);
 	if (irq < 0) {
@@ -167,6 +167,11 @@ static int dw_i2c_probe(struct platform_device *pdev)
 		of_property_read_u32(pdev->dev.of_node,
 				     "i2c-scl-falling-time-ns",
 				     &dev->scl_falling_time);
+
+		ret = of_property_read_u32(pdev->dev.of_node,
+					   "speed-mode", &speed_prop);
+		if (!ret && (speed_prop == 0))
+			speed = DW_IC_CON_SPEED_STD;
 	}
 
 	dev->functionality =
@@ -177,7 +182,7 @@ static int dw_i2c_probe(struct platform_device *pdev)
 		I2C_FUNC_SMBUS_WORD_DATA |
 		I2C_FUNC_SMBUS_I2C_BLOCK;
 	dev->master_cfg =  DW_IC_CON_MASTER | DW_IC_CON_SLAVE_DISABLE |
-		DW_IC_CON_RESTART_EN | DW_IC_CON_SPEED_FAST;
+		DW_IC_CON_RESTART_EN | speed;
 
 	/* Try first if we can configure the device from ACPI */
 	r = dw_i2c_acpi_configure(pdev);
-- 
1.7.9.5

Re: [PATCH 1/2] i2c: designware: device tree bindings for i2c speed mode

[Wolfram Sang]

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On Tue, Aug 19, 2014 at 01:34:35PM -0500, atull@opensource.altera.com wrote:
> From: Alan Tull <atull@opensource.altera.com>
> 
> Add "speed-mode" Device Tree property to select between
> standard and fast i2c mode.  Previously, driver was hardwired
> as fast mode.  Default to fast mode if property is not
> present.

NACK. This should be deduced from the clock-frequency setting...

> 
> Signed-off-by: Alan Tull <atull@opensource.altera.com>
> ---
>  .../devicetree/bindings/i2c/i2c-designware.txt     |    3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/i2c/i2c-designware.txt b/Documentation/devicetree/bindings/i2c/i2c-designware.txt
> index 5199b0c..0e4cd21 100644
> --- a/Documentation/devicetree/bindings/i2c/i2c-designware.txt
> +++ b/Documentation/devicetree/bindings/i2c/i2c-designware.txt
> @@ -9,6 +9,8 @@ Required properties :
>  Recommended properties :
>  
>   - clock-frequency : desired I2C bus clock frequency in Hz.

... which is described here, but surprisingly not supported in the
driver yet :(

Check i2c-riic for an example.

> + - speed-mode      : 0 = standard (0 - 100Kb/s)
> +                   : 1 = fast (<= 400Kb/s) <== default
>  
>  Optional properties :
>   - i2c-sda-hold-time-ns : should contain the SDA hold time in nanoseconds.
> @@ -29,6 +31,7 @@ Example :
>  		reg = <0xf0000 0x1000>;
>  		interrupts = <11>;
>  		clock-frequency = <400000>;
> +		speed-mode = <0>;
>  	};
>  
>  	i2c@1120000 {
> -- 
> 1.7.9.5
> 

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Re: [PATCH 1/2] i2c: designware: device tree bindings for i2c speed mode

[atull]

On Tue, 19 Aug 2014, Wolfram Sang wrote:

> On Tue, Aug 19, 2014 at 01:34:35PM -0500, atull@opensource.altera.com wrote:
> > From: Alan Tull <atull@opensource.altera.com>
> > 
> > Add "speed-mode" Device Tree property to select between
> > standard and fast i2c mode.  Previously, driver was hardwired
> > as fast mode.  Default to fast mode if property is not
> > present.
> 
> NACK. This should be deduced from the clock-frequency setting...

I just sent out a new patch that looks at the clock-frequency setting.

Alan

Re: [PATCH 1/2] i2c: designware: device tree bindings for i2c speed mode

[Mark Rutland]

On Tue, Aug 19, 2014 at 07:34:35PM +0100, atull@opensource.altera.com wrote:
> From: Alan Tull <atull@opensource.altera.com>
> 
> Add "speed-mode" Device Tree property to select between
> standard and fast i2c mode.  Previously, driver was hardwired
> as fast mode.  Default to fast mode if property is not
> present.
> 
> Signed-off-by: Alan Tull <atull@opensource.altera.com>
> ---
>  .../devicetree/bindings/i2c/i2c-designware.txt     |    3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/i2c/i2c-designware.txt b/Documentation/devicetree/bindings/i2c/i2c-designware.txt
> index 5199b0c..0e4cd21 100644
> --- a/Documentation/devicetree/bindings/i2c/i2c-designware.txt
> +++ b/Documentation/devicetree/bindings/i2c/i2c-designware.txt
> @@ -9,6 +9,8 @@ Required properties :
>  Recommended properties :
>  
>   - clock-frequency : desired I2C bus clock frequency in Hz.
> + - speed-mode      : 0 = standard (0 - 100Kb/s)
> +                   : 1 = fast (<= 400Kb/s) <== default

This is a bit opaque.

Is this a limit on the max bit-rate the device should operate at?

Why not just have an optional boolean property to limit to standard
speed?

Thanks,
Mark.

>  
>  Optional properties :
>   - i2c-sda-hold-time-ns : should contain the SDA hold time in nanoseconds.
> @@ -29,6 +31,7 @@ Example :
>  		reg = <0xf0000 0x1000>;
>  		interrupts = <11>;
>  		clock-frequency = <400000>;
> +		speed-mode = <0>;
>  	};
>  
>  	i2c@1120000 {
> -- 
> 1.7.9.5
> 
> --
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Re: [PATCH 1/2] i2c: designware: device tree bindings for i2c speed mode

[Mark Rutland]

On Wed, Aug 20, 2014 at 10:34:59AM +0100, Mark Rutland wrote:
> On Tue, Aug 19, 2014 at 07:34:35PM +0100, atull@opensource.altera.com wrote:
> > From: Alan Tull <atull@opensource.altera.com>
> > 
> > Add "speed-mode" Device Tree property to select between
> > standard and fast i2c mode.  Previously, driver was hardwired
> > as fast mode.  Default to fast mode if property is not
> > present.
> > 
> > Signed-off-by: Alan Tull <atull@opensource.altera.com>
> > ---
> >  .../devicetree/bindings/i2c/i2c-designware.txt     |    3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/i2c/i2c-designware.txt b/Documentation/devicetree/bindings/i2c/i2c-designware.txt
> > index 5199b0c..0e4cd21 100644
> > --- a/Documentation/devicetree/bindings/i2c/i2c-designware.txt
> > +++ b/Documentation/devicetree/bindings/i2c/i2c-designware.txt
> > @@ -9,6 +9,8 @@ Required properties :
> >  Recommended properties :
> >  
> >   - clock-frequency : desired I2C bus clock frequency in Hz.
> > + - speed-mode      : 0 = standard (0 - 100Kb/s)
> > +                   : 1 = fast (<= 400Kb/s) <== default
> 
> This is a bit opaque.
> 
> Is this a limit on the max bit-rate the device should operate at?
> 
> Why not just have an optional boolean property to limit to standard
> speed?

I see there's a new patch doing this based on clock-frequency, so feel
free to ignore this.

Mark.