[PATCH 0/7] devicetree cleanup for i2c muxes/arbs/gates

[PATCH 0/7] devicetree cleanup for i2c muxes/arbs/gates

[Peter Rosin]

Hi!

The nxp pca9541 chip does not have any devicetree bindings.
When trying to write such bindings matching the implementation,
I stumbled upon something which I did not like. I had to
give the node holding the i2c child bus a 'reg' property that
is left unused and is really odd to explain from a devicetree
point of view. It really is a leftover from the fact that linux
implements i2c arbitrators (and i2c gates) using the i2c mux
code. See this thread for history [1].

This series resolves the issues, and maintains backwards compat
with old device trees (well, one could, in theory, create a
device tree that would break with these changes, but my guess
is that the odds for that happening inadvertedly are high...)

This should also help Crestez Dan Leonard with the mpu6050
series containing the changes for its auxiliary i2c master [2],
especially if you also consider the recent (very similar) changes
from Jon Hunter that adds an optional 'i2c-bus' subnode [3].

If this is ok, I will follow up with patches for other drivers
so that they inform the i2c mux core if they are muxes, arbs or
gates. As stated, they will continue to work with these changes,
so there is no huge rush.

The mux core does not really need to differentiate between
arbitrators and gates. Should they be folded? What to call them
in that case?

Cheers,
Peter

[1] https://lkml.org/lkml/2016/6/27/203
[2] https://lkml.org/lkml/2016/5/18/355
[3] https://patchwork.ozlabs.org/patch/641934/

Peter Rosin (7):
  dt-bindings: i2c: add support for 'i2c-mux' subnode
  dt-bindings: i2c: add support for 'i2c-arb' subnode
  dt-bindings: i2c: add support for 'i2c-gate' subnode
  dt-bindings: i2c: add bindings for nxp,pca9541
  i2c: mux: add support for 'i2c-mux', 'i2c-arb' and 'i2c-gate' DT
    subnodes
  i2c: pca9541: add device tree binding
  i2c: pca954x: add device tree binding

 .../bindings/i2c/i2c-arb-gpio-challenge.txt        |  8 +---
 Documentation/devicetree/bindings/i2c/i2c-arb.txt  | 35 ++++++++++++++++
 Documentation/devicetree/bindings/i2c/i2c-gate.txt | 35 ++++++++++++++++
 Documentation/devicetree/bindings/i2c/i2c-mux.txt  | 23 ++++++++---
 .../devicetree/bindings/i2c/nxp,pca9541.txt        | 29 ++++++++++++++
 MAINTAINERS                                        |  2 +
 drivers/i2c/i2c-mux.c                              | 44 +++++++++++++++++----
 drivers/i2c/muxes/i2c-mux-pca9541.c                |  8 ++++
 drivers/i2c/muxes/i2c-mux-pca954x.c                | 46 ++++++++++++++++------
 include/linux/i2c-mux.h                            |  8 +++-
 10 files changed, 205 insertions(+), 33 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/i2c/i2c-arb.txt
 create mode 100644 Documentation/devicetree/bindings/i2c/i2c-gate.txt
 create mode 100644 Documentation/devicetree/bindings/i2c/nxp,pca9541.txt

-- 
2.1.4

[PATCH 1/7] dt-bindings: i2c: add support for 'i2c-mux' subnode

[Peter Rosin]

Similar to the new optional 'i2c-bus' subnode from Jon Hunter, this
adds an optional 'i2c-mux' subnode, for similar reasons. I.e. it is
bad of the i2c mux core to assume that any subnode of an i2c mux device
is a potential (when the 'reg' property matches) i2c-mux child bus,
given that i2c mux devices might do more than mux i2c traffic.

So, if an 'i2c-mux' subnode is present, dictate that all i2c-mux child
buses exist beneath that subnode.

Signed-off-by: Peter Rosin <peda@axentia.se>
---
 Documentation/devicetree/bindings/i2c/i2c-mux.txt | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/Documentation/devicetree/bindings/i2c/i2c-mux.txt b/Documentation/devicetree/bindings/i2c/i2c-mux.txt
index af84cce5cd7b..212e6779dc5c 100644
--- a/Documentation/devicetree/bindings/i2c/i2c-mux.txt
+++ b/Documentation/devicetree/bindings/i2c/i2c-mux.txt
@@ -2,19 +2,32 @@ Common i2c bus multiplexer/switch properties.
 
 An i2c bus multiplexer/switch will have several child busses that are
 numbered uniquely in a device dependent manner.  The nodes for an i2c bus
-multiplexer/switch will have one child node for each child
-bus.
+multiplexer/switch will have one child node for each child bus.
 
-Required properties:
+Optional properties:
+- #address-cells = <1>;
+   This property is required is the i2c-mux child node does not exist.
+
+- #size-cells = <0>;
+   This property is required is the i2c-mux child node does not exist.
+
+- i2c-mux
+   For i2c multiplexers/switches that have child nodes that are a mixture
+   of both i2c child busses and other child nodes, the 'i2c-mux' subnode
+   can be used for populating the i2c child busses.  If an 'i2c-mux'
+   subnode is present, only subnodes of this will be considered as i2c
+   child busses.
+
+Required properties for the i2c-mux child node:
 - #address-cells = <1>;
 - #size-cells = <0>;
 
-Required properties for child nodes:
+Required properties for i2c child bus nodes:
 - #address-cells = <1>;
 - #size-cells = <0>;
 - reg : The sub-bus number.
 
-Optional properties for child nodes:
+Optional properties for i2c child bus nodes:
 - Other properties specific to the multiplexer/switch hardware.
 - Child nodes conforming to i2c bus binding
 
-- 
2.1.4

Re: [PATCH 1/7] dt-bindings: i2c: add support for 'i2c-mux' subnode

[Rob Herring]

On Wed, Jul 27, 2016 at 10:43:24AM +0200, Peter Rosin wrote:
> Similar to the new optional 'i2c-bus' subnode from Jon Hunter, this
> adds an optional 'i2c-mux' subnode, for similar reasons. I.e. it is
> bad of the i2c mux core to assume that any subnode of an i2c mux device
> is a potential (when the 'reg' property matches) i2c-mux child bus,
> given that i2c mux devices might do more than mux i2c traffic.
> 
> So, if an 'i2c-mux' subnode is present, dictate that all i2c-mux child
> buses exist beneath that subnode.
> 
> Signed-off-by: Peter Rosin <peda@axentia.se>
> ---
>  Documentation/devicetree/bindings/i2c/i2c-mux.txt | 23 ++++++++++++++++++-----
>  1 file changed, 18 insertions(+), 5 deletions(-)

Acked-by: Rob Herring <robh@kernel.org>

[PATCH 2/7] dt-bindings: i2c: add support for 'i2c-arb' subnode

[Peter Rosin]

This gets rid of the need for a pointless 'reg' property for i2c
arbitrators.

I.e. this new and more compact style

	some-arbitrator {
		i2c-mux {
			#address-cells = <1>;
			#size-cells = <0>;

			some-i2c-device@50 {
				reg = <0x50>;
			};
		};
	};

instead of the old

	some-arbitrator {
		#address-cells = <1>;
		#size-cells = <0>;

		i2c@0 {
			reg = <0>;

			#address-cells = <1>;
			#size-cells = <0>;

			some-i2c-device@50 {
				reg = <0x50>;
			};
		};
	};

Signed-off-by: Peter Rosin <peda@axentia.se>
---
 .../bindings/i2c/i2c-arb-gpio-challenge.txt        |  8 ++---
 Documentation/devicetree/bindings/i2c/i2c-arb.txt  | 35 ++++++++++++++++++++++
 MAINTAINERS                                        |  1 +
 3 files changed, 38 insertions(+), 6 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/i2c/i2c-arb.txt

diff --git a/Documentation/devicetree/bindings/i2c/i2c-arb-gpio-challenge.txt b/Documentation/devicetree/bindings/i2c/i2c-arb-gpio-challenge.txt
index 71191ff0e781..248a155414c2 100644
--- a/Documentation/devicetree/bindings/i2c/i2c-arb-gpio-challenge.txt
+++ b/Documentation/devicetree/bindings/i2c/i2c-arb-gpio-challenge.txt
@@ -44,8 +44,7 @@ Required properties:
 - our-claim-gpio: The GPIO that we use to claim the bus.
 - their-claim-gpios: The GPIOs that the other sides use to claim the bus.
   Note that some implementations may only support a single other master.
-- Standard I2C mux properties. See i2c-mux.txt in this directory.
-- Single I2C child bus node at reg 0. See i2c-mux.txt in this directory.
+- I2C arbitration bus node. See i2c-arb.txt in this directory.
 
 Optional properties:
 - slew-delay-us: microseconds to wait for a GPIO to go high. Default is 10 us.
@@ -63,8 +62,6 @@ Example:
 
 	i2c-arbitrator {
 		compatible = "i2c-arb-gpio-challenge";
-		#address-cells = <1>;
-		#size-cells = <0>;
 
 		i2c-parent = <&{/i2c@12CA0000}>;
 
@@ -74,8 +71,7 @@ Example:
 		wait-retry-us = <3000>;
 		wait-free-us = <50000>;
 
-		i2c@0 {
-			reg = <0>;
+		i2c-arb {
 			#address-cells = <1>;
 			#size-cells = <0>;
 
diff --git a/Documentation/devicetree/bindings/i2c/i2c-arb.txt b/Documentation/devicetree/bindings/i2c/i2c-arb.txt
new file mode 100644
index 000000000000..59abf9277bdc
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/i2c-arb.txt
@@ -0,0 +1,35 @@
+Common i2c arbitration bus properties.
+
+- i2c-arb child node
+
+Required properties for the i2c-arb child node:
+- #address-cells = <1>;
+- #size-cells = <0>;
+
+Optional properties for i2c-arb child node:
+- Child nodes conforming to i2c bus binding
+
+
+Example :
+
+	/*
+	   An NXP pca9541 I2C bus master selector at address 0x74
+	   with a NXP pca8574 GPIO expander attached.
+	 */
+
+	arb@74 {
+		compatible = "nxp,pca9541";
+		reg = <0x74>;
+
+		i2c-arb {
+			#address-cells = <1>;
+			#size-cells = <0>;
+
+			gpio@38 {
+				compatible = "nxp,pca8574";
+				reg = <0x38>;
+				#gpio-cells = <2>;
+				gpio-controller;
+			};
+		};
+	};
diff --git a/MAINTAINERS b/MAINTAINERS
index 8c20323d1277..543052305a09 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5524,6 +5524,7 @@ S:	Maintained
 F:	Documentation/i2c/i2c-topology
 F:	Documentation/i2c/muxes/
 F:	Documentation/devicetree/bindings/i2c/i2c-mux*
+F:	Documentation/devicetree/bindings/i2c/i2c-arb*
 F:	drivers/i2c/i2c-mux.c
 F:	drivers/i2c/muxes/
 F:	include/linux/i2c-mux.h
-- 
2.1.4

Re: [PATCH 2/7] dt-bindings: i2c: add support for 'i2c-arb' subnode

[Rob Herring]

On Wed, Jul 27, 2016 at 10:43:25AM +0200, Peter Rosin wrote:
> This gets rid of the need for a pointless 'reg' property for i2c
> arbitrators.
> 
> I.e. this new and more compact style
> 
> 	some-arbitrator {
> 		i2c-mux {

You mean i2c-arb here?

> 			#address-cells = <1>;
> 			#size-cells = <0>;
> 
> 			some-i2c-device@50 {
> 				reg = <0x50>;
> 			};
> 		};
> 	};
> 
> instead of the old
> 
> 	some-arbitrator {
> 		#address-cells = <1>;
> 		#size-cells = <0>;
> 
> 		i2c@0 {
> 			reg = <0>;
> 
> 			#address-cells = <1>;
> 			#size-cells = <0>;
> 
> 			some-i2c-device@50 {
> 				reg = <0x50>;
> 			};
> 		};
> 	};
> 
> Signed-off-by: Peter Rosin <peda@axentia.se>
> ---
>  .../bindings/i2c/i2c-arb-gpio-challenge.txt        |  8 ++---
>  Documentation/devicetree/bindings/i2c/i2c-arb.txt  | 35 ++++++++++++++++++++++
>  MAINTAINERS                                        |  1 +
>  3 files changed, 38 insertions(+), 6 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/i2c/i2c-arb.txt

Otherwise,

Acked-by: Rob Herring <robh@kernel.org>

[PATCH 3/7] dt-bindings: i2c: add support for 'i2c-gate' subnode

[Peter Rosin]

Handle i2c gates similarly to how i2c arbitrators are handled.
This gets rid of a pointless 'reg' property for i2c gates.

I.e. this new and more compact style

        some-gate {
                i2c-gate {
                        #address-cells = <1>;
                        #size-cells = <0>;

                        some-i2c-device@50 {
                                reg = <0x50>;
                        };
                };
        };

instead of the old

        some-gate {
                #address-cells = <1>;
                #size-cells = <0>;

                i2c@0 {
                        reg = <0>;

                        #address-cells = <1>;
                        #size-cells = <0>;

                        some-i2c-device@50 {
                                reg = <0x50>;
                        };
                };
        };

Signed-off-by: Peter Rosin <peda@axentia.se>
---
 Documentation/devicetree/bindings/i2c/i2c-gate.txt | 35 ++++++++++++++++++++++
 MAINTAINERS                                        |  1 +
 2 files changed, 36 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/i2c/i2c-gate.txt

diff --git a/Documentation/devicetree/bindings/i2c/i2c-gate.txt b/Documentation/devicetree/bindings/i2c/i2c-gate.txt
new file mode 100644
index 000000000000..78f17892dfc6
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/i2c-gate.txt
@@ -0,0 +1,35 @@
+Common i2c gate properties.
+
+- i2c-gate child node
+
+Required properties for the i2c-gate child node:
+- #address-cells = <1>;
+- #size-cells = <0>;
+
+Optional properties for i2c-gate child node:
+- Child nodes conforming to i2c bus binding
+
+
+Example :
+
+	/*
+	   An Invensense mpu9150 at address 0x68 featuring an on-chip Asahi
+	   Kasei ak8975 compass behind a gate.
+	 */
+
+	mpu9150@68 {
+		compatible = "invensense,mpu9150";
+		reg = <0x68>;
+		interrupt-parent = <&gpio1>;
+		interrupts = <18 1>;
+
+		i2c-gate {
+			#address-cells = <1>;
+			#size-cells = <0>;
+
+			ax8975@0c {
+				compatible = "ak,ak8975";
+				reg = <0x0c>;
+			};
+		};
+	};
diff --git a/MAINTAINERS b/MAINTAINERS
index 543052305a09..0e6cc071c480 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5525,6 +5525,7 @@ F:	Documentation/i2c/i2c-topology
 F:	Documentation/i2c/muxes/
 F:	Documentation/devicetree/bindings/i2c/i2c-mux*
 F:	Documentation/devicetree/bindings/i2c/i2c-arb*
+F:	Documentation/devicetree/bindings/i2c/i2c-gate*
 F:	drivers/i2c/i2c-mux.c
 F:	drivers/i2c/muxes/
 F:	include/linux/i2c-mux.h
-- 
2.1.4

Re: [PATCH 3/7] dt-bindings: i2c: add support for 'i2c-gate' subnode

[Rob Herring]

On Wed, Jul 27, 2016 at 10:43:26AM +0200, Peter Rosin wrote:
> Handle i2c gates similarly to how i2c arbitrators are handled.
> This gets rid of a pointless 'reg' property for i2c gates.
> 
> I.e. this new and more compact style
> 
>         some-gate {
>                 i2c-gate {
>                         #address-cells = <1>;
>                         #size-cells = <0>;
> 
>                         some-i2c-device@50 {
>                                 reg = <0x50>;
>                         };
>                 };
>         };
> 
> instead of the old
> 
>         some-gate {
>                 #address-cells = <1>;
>                 #size-cells = <0>;
> 
>                 i2c@0 {
>                         reg = <0>;
> 
>                         #address-cells = <1>;
>                         #size-cells = <0>;
> 
>                         some-i2c-device@50 {
>                                 reg = <0x50>;
>                         };
>                 };
>         };
> 
> Signed-off-by: Peter Rosin <peda@axentia.se>
> ---
>  Documentation/devicetree/bindings/i2c/i2c-gate.txt | 35 ++++++++++++++++++++++
>  MAINTAINERS                                        |  1 +
>  2 files changed, 36 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/i2c/i2c-gate.txt
> 
> diff --git a/Documentation/devicetree/bindings/i2c/i2c-gate.txt b/Documentation/devicetree/bindings/i2c/i2c-gate.txt
> new file mode 100644
> index 000000000000..78f17892dfc6
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/i2c/i2c-gate.txt
> @@ -0,0 +1,35 @@
> +Common i2c gate properties.

Perhaps define what a gate is.

> +
> +- i2c-gate child node
> +
> +Required properties for the i2c-gate child node:
> +- #address-cells = <1>;
> +- #size-cells = <0>;
> +
> +Optional properties for i2c-gate child node:
> +- Child nodes conforming to i2c bus binding
> +
> +
> +Example :
> +
> +	/*
> +	   An Invensense mpu9150 at address 0x68 featuring an on-chip Asahi
> +	   Kasei ak8975 compass behind a gate.
> +	 */
> +
> +	mpu9150@68 {
> +		compatible = "invensense,mpu9150";
> +		reg = <0x68>;
> +		interrupt-parent = <&gpio1>;
> +		interrupts = <18 1>;
> +
> +		i2c-gate {
> +			#address-cells = <1>;
> +			#size-cells = <0>;
> +
> +			ax8975@0c {
> +				compatible = "ak,ak8975";
> +				reg = <0x0c>;
> +			};
> +		};
> +	};
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 543052305a09..0e6cc071c480 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -5525,6 +5525,7 @@ F:	Documentation/i2c/i2c-topology
>  F:	Documentation/i2c/muxes/
>  F:	Documentation/devicetree/bindings/i2c/i2c-mux*
>  F:	Documentation/devicetree/bindings/i2c/i2c-arb*
> +F:	Documentation/devicetree/bindings/i2c/i2c-gate*
>  F:	drivers/i2c/i2c-mux.c
>  F:	drivers/i2c/muxes/
>  F:	include/linux/i2c-mux.h
> -- 
> 2.1.4
> 

Re: [PATCH 3/7] dt-bindings: i2c: add support for 'i2c-gate' subnode

[Peter Rosin]

On 2016-07-29 23:25, Rob Herring wrote:
> On Wed, Jul 27, 2016 at 10:43:26AM +0200, Peter Rosin wrote:
>> Handle i2c gates similarly to how i2c arbitrators are handled.
>> This gets rid of a pointless 'reg' property for i2c gates.
>>
>> I.e. this new and more compact style
>>
>>         some-gate {
>>                 i2c-gate {
>>                         #address-cells = <1>;
>>                         #size-cells = <0>;
>>
>>                         some-i2c-device@50 {
>>                                 reg = <0x50>;
>>                         };
>>                 };
>>         };
>>
>> instead of the old
>>
>>         some-gate {
>>                 #address-cells = <1>;
>>                 #size-cells = <0>;
>>
>>                 i2c@0 {
>>                         reg = <0>;
>>
>>                         #address-cells = <1>;
>>                         #size-cells = <0>;
>>
>>                         some-i2c-device@50 {
>>                                 reg = <0x50>;
>>                         };
>>                 };
>>         };
>>
>> Signed-off-by: Peter Rosin <peda@axentia.se>
>> ---
>>  Documentation/devicetree/bindings/i2c/i2c-gate.txt | 35 ++++++++++++++++++++++
>>  MAINTAINERS                                        |  1 +
>>  2 files changed, 36 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/i2c/i2c-gate.txt
>>
>> diff --git a/Documentation/devicetree/bindings/i2c/i2c-gate.txt b/Documentation/devicetree/bindings/i2c/i2c-gate.txt
>> new file mode 100644
>> index 000000000000..78f17892dfc6
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/i2c/i2c-gate.txt
>> @@ -0,0 +1,35 @@
>> +Common i2c gate properties.
> 
> Perhaps define what a gate is.

How about the following paragraph at the very top of the file?

An i2c gate is useful to e.g. reduce the digital noise for RF tuners connected
to the i2c bus. Gates are similar to arbitrators in that you need to perform
some kind of operation to access the i2c bus past the arbitrator/gate, but
there are no competing masters to consider for gates and therefore there is
no arbitration happening for gates.

>> +
>> +- i2c-gate child node
>> +
>> +Required properties for the i2c-gate child node:
>> +- #address-cells = <1>;
>> +- #size-cells = <0>;
>> +
>> +Optional properties for i2c-gate child node:
>> +- Child nodes conforming to i2c bus binding
>> +
>> +
>> +Example :
>> +
>> +	/*
>> +	   An Invensense mpu9150 at address 0x68 featuring an on-chip Asahi
>> +	   Kasei ak8975 compass behind a gate.
>> +	 */
>> +
>> +	mpu9150@68 {
>> +		compatible = "invensense,mpu9150";
>> +		reg = <0x68>;
>> +		interrupt-parent = <&gpio1>;
>> +		interrupts = <18 1>;
>> +
>> +		i2c-gate {
>> +			#address-cells = <1>;
>> +			#size-cells = <0>;
>> +
>> +			ax8975@0c {
>> +				compatible = "ak,ak8975";
>> +				reg = <0x0c>;
>> +			};
>> +		};
>> +	};
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index 543052305a09..0e6cc071c480 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -5525,6 +5525,7 @@ F:	Documentation/i2c/i2c-topology
>>  F:	Documentation/i2c/muxes/
>>  F:	Documentation/devicetree/bindings/i2c/i2c-mux*
>>  F:	Documentation/devicetree/bindings/i2c/i2c-arb*
>> +F:	Documentation/devicetree/bindings/i2c/i2c-gate*
>>  F:	drivers/i2c/i2c-mux.c
>>  F:	drivers/i2c/muxes/
>>  F:	include/linux/i2c-mux.h
>> -- 
>> 2.1.4
>>

[PATCH 4/7] dt-bindings: i2c: add bindings for nxp,pca9541

[Peter Rosin]

Fill the gap for this pre-existing driver.

Signed-off-by: Peter Rosin <peda@axentia.se>
---
 .../devicetree/bindings/i2c/nxp,pca9541.txt        | 29 ++++++++++++++++++++++
 1 file changed, 29 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/i2c/nxp,pca9541.txt

diff --git a/Documentation/devicetree/bindings/i2c/nxp,pca9541.txt b/Documentation/devicetree/bindings/i2c/nxp,pca9541.txt
new file mode 100644
index 000000000000..0fbbc6970ec5
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/nxp,pca9541.txt
@@ -0,0 +1,29 @@
+* NXP PCA9541 I2C bus master selector
+
+Required Properties:
+
+  - compatible: Must be "nxp,pca9541"
+
+  - reg: The I2C address of the device.
+
+  The following required properties are defined externally:
+
+  - I2C arbitration bus node. See i2c-arb.txt in this directory.
+
+
+Example:
+
+	i2c-arbitrator@74 {
+		compatible = "nxp,pca9541";
+		reg = <0x74>;
+
+		i2c-arb {
+			#address-cells = <1>;
+			#size-cells = <0>;
+
+			eeprom@54 {
+				compatible = "at,24c08";
+				reg = <0x54>;
+			};
+		};
+	};
-- 
2.1.4

Re: [PATCH 4/7] dt-bindings: i2c: add bindings for nxp,pca9541

[Rob Herring]

On Wed, Jul 27, 2016 at 10:43:27AM +0200, Peter Rosin wrote:
> Fill the gap for this pre-existing driver.
> 
> Signed-off-by: Peter Rosin <peda@axentia.se>
> ---
>  .../devicetree/bindings/i2c/nxp,pca9541.txt        | 29 ++++++++++++++++++++++
>  1 file changed, 29 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/i2c/nxp,pca9541.txt

Acked-by: Rob Herring <robh@kernel.org>

[PATCH 5/7] i2c: mux: add support for 'i2c-mux', 'i2c-arb' and 'i2c-gate' DT subnodes

[Peter Rosin]

Backwards compatibility is preserved; the subnodes are in practice
optional.

However, the mux core needs to know what subnode it should examine, so add
a couple of new flags for i2c_mux_alloc for this purpose.

The rule is that if the mux core finds a 'reg' property in the appropriate
subnode, e.g. if 'reg' exists in the 'i2c-mux' subnode, then the mux core
will assume that this is an old style entry and not an i2c-mux subnode
(correspondingly for arbitrators and gates with 'i2c-arb' and 'i2c-gate').

Signed-off-by: Peter Rosin <peda@axentia.se>
---
 drivers/i2c/i2c-mux.c   | 44 ++++++++++++++++++++++++++++++++++++--------
 include/linux/i2c-mux.h |  8 ++++++--
 2 files changed, 42 insertions(+), 10 deletions(-)

diff --git a/drivers/i2c/i2c-mux.c b/drivers/i2c/i2c-mux.c
index 8eee98634cda..c1ae719d1a7a 100644
--- a/drivers/i2c/i2c-mux.c
+++ b/drivers/i2c/i2c-mux.c
@@ -255,6 +255,10 @@ struct i2c_mux_core *i2c_mux_alloc(struct i2c_adapter *parent,
 	muxc->dev = dev;
 	if (flags & I2C_MUX_LOCKED)
 		muxc->mux_locked = true;
+	if (flags & I2C_MUX_ARBITRATOR)
+		muxc->arbitrator = true;
+	if (flags & I2C_MUX_GATE)
+		muxc->gate = true;
 	muxc->select = select;
 	muxc->deselect = deselect;
 	muxc->max_adapters = max_adapters;
@@ -335,18 +339,42 @@ int i2c_mux_add_adapter(struct i2c_mux_core *muxc,
 	 * nothing if !CONFIG_OF.
 	 */
 	if (muxc->dev->of_node) {
-		struct device_node *child;
+		struct device_node *dev_node = muxc->dev->of_node;
+		struct device_node *mux_node, *child = NULL;
 		u32 reg;
 
-		for_each_child_of_node(muxc->dev->of_node, child) {
-			ret = of_property_read_u32(child, "reg", &reg);
-			if (ret)
-				continue;
-			if (chan_id == reg) {
-				priv->adap.dev.of_node = child;
-				break;
+		if (muxc->arbitrator)
+			mux_node = of_get_child_by_name(dev_node, "i2c-arb");
+		else if (muxc->gate)
+			mux_node = of_get_child_by_name(dev_node, "i2c-gate");
+		else
+			mux_node = of_get_child_by_name(dev_node, "i2c-mux");
+
+		if (mux_node) {
+			/* A "reg" property indicates an old-style DT entry */
+			if (!of_property_read_u32(mux_node, "reg", &reg)) {
+				of_node_put(mux_node);
+				mux_node = NULL;
+			}
+		}
+
+		if (!mux_node)
+			mux_node = of_node_get(dev_node);
+		else if (muxc->arbitrator || muxc->gate)
+			child = of_node_get(mux_node);
+
+		if (!child) {
+			for_each_child_of_node(mux_node, child) {
+				ret = of_property_read_u32(child, "reg", &reg);
+				if (ret)
+					continue;
+				if (chan_id == reg)
+					break;
 			}
 		}
+
+		priv->adap.dev.of_node = child;
+		of_node_put(mux_node);
 	}
 
 	/*
diff --git a/include/linux/i2c-mux.h b/include/linux/i2c-mux.h
index d4c1d12f900d..bd74d5706f3b 100644
--- a/include/linux/i2c-mux.h
+++ b/include/linux/i2c-mux.h
@@ -32,7 +32,9 @@
 struct i2c_mux_core {
 	struct i2c_adapter *parent;
 	struct device *dev;
-	bool mux_locked;
+	unsigned int mux_locked:1;
+	unsigned int arbitrator:1;
+	unsigned int gate:1;
 
 	void *priv;
 
@@ -51,7 +53,9 @@ struct i2c_mux_core *i2c_mux_alloc(struct i2c_adapter *parent,
 				   int (*deselect)(struct i2c_mux_core *, u32));
 
 /* flags for i2c_mux_alloc */
-#define I2C_MUX_LOCKED BIT(0)
+#define I2C_MUX_LOCKED     BIT(0)
+#define I2C_MUX_ARBITRATOR BIT(1)
+#define I2C_MUX_GATE       BIT(2)
 
 static inline void *i2c_mux_priv(struct i2c_mux_core *muxc)
 {
-- 
2.1.4

[PATCH 6/7] i2c: pca9541: add device tree binding

[Peter Rosin]

Signed-off-by: Peter Rosin <peda@axentia.se>
---
 drivers/i2c/muxes/i2c-mux-pca9541.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/i2c/muxes/i2c-mux-pca9541.c b/drivers/i2c/muxes/i2c-mux-pca9541.c
index 3cb8af635db5..40e137ae242e 100644
--- a/drivers/i2c/muxes/i2c-mux-pca9541.c
+++ b/drivers/i2c/muxes/i2c-mux-pca9541.c
@@ -85,6 +85,13 @@ static const struct i2c_device_id pca9541_id[] = {
 
 MODULE_DEVICE_TABLE(i2c, pca9541_id);
 
+#ifdef CONFIG_OF
+static const struct of_device_id pca9541_of_match[] = {
+	{ .compatible = "nxp,pca9541" },
+	{}
+};
+#endif
+
 /*
  * Write to chip register. Don't use i2c_transfer()/i2c_smbus_xfer()
  * as they will try to lock the adapter a second time.
@@ -382,6 +389,7 @@ static int pca9541_remove(struct i2c_client *client)
 static struct i2c_driver pca9541_driver = {
 	.driver = {
 		   .name = "pca9541",
+		   .of_match_table = of_match_ptr(pca9541_of_match),
 		   },
 	.probe = pca9541_probe,
 	.remove = pca9541_remove,
-- 
2.1.4

[PATCH 7/7] i2c: pca954x: add device tree binding

[Peter Rosin]

Signed-off-by: Peter Rosin <peda@axentia.se>
---
 drivers/i2c/muxes/i2c-mux-pca954x.c | 46 +++++++++++++++++++++++++++----------
 1 file changed, 34 insertions(+), 12 deletions(-)

diff --git a/drivers/i2c/muxes/i2c-mux-pca954x.c b/drivers/i2c/muxes/i2c-mux-pca954x.c
index 528e755c468f..6dfd31ba29a0 100644
--- a/drivers/i2c/muxes/i2c-mux-pca954x.c
+++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
@@ -42,6 +42,7 @@
 #include <linux/i2c/pca954x.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/of_device.h>
 #include <linux/pm.h>
 #include <linux/slab.h>
 
@@ -58,14 +59,6 @@ enum pca_type {
 	pca_9548,
 };
 
-struct pca954x {
-	enum pca_type type;
-
-	u8 last_chan;		/* last register value */
-	u8 deselect;
-	struct i2c_client *client;
-};
-
 struct chip_desc {
 	u8 nchans;
 	u8 enable;	/* used for muxes only */
@@ -75,6 +68,14 @@ struct chip_desc {
 	} muxtype;
 };
 
+struct pca954x {
+	const struct chip_desc *chip;
+
+	u8 last_chan;		/* last register value */
+	u8 deselect;
+	struct i2c_client *client;
+};
+
 /* Provide specs for the PCA954x types we know about */
 static const struct chip_desc chips[] = {
 	[pca_9540] = {
@@ -119,6 +120,20 @@ static const struct i2c_device_id pca954x_id[] = {
 };
 MODULE_DEVICE_TABLE(i2c, pca954x_id);
 
+#ifdef CONFIG_OF
+static const struct of_device_id pca954x_of_match[] = {
+	{ .compatible = "nxp,pca9540", .data = &chips[pca_9540] },
+	{ .compatible = "nxp,pca9542", .data = &chips[pca_9542] },
+	{ .compatible = "nxp,pca9543", .data = &chips[pca_9543] },
+	{ .compatible = "nxp,pca9544", .data = &chips[pca_9544] },
+	{ .compatible = "nxp,pca9545", .data = &chips[pca_9545] },
+	{ .compatible = "nxp,pca9546", .data = &chips[pca_9546] },
+	{ .compatible = "nxp,pca9547", .data = &chips[pca_9547] },
+	{ .compatible = "nxp,pca9548", .data = &chips[pca_9548] },
+	{}
+};
+#endif
+
 /* Write to mux register. Don't use i2c_transfer()/i2c_smbus_xfer()
    for this as they will try to lock adapter a second time */
 static int pca954x_reg_write(struct i2c_adapter *adap,
@@ -151,7 +166,7 @@ static int pca954x_select_chan(struct i2c_mux_core *muxc, u32 chan)
 {
 	struct pca954x *data = i2c_mux_priv(muxc);
 	struct i2c_client *client = data->client;
-	const struct chip_desc *chip = &chips[data->type];
+	const struct chip_desc *chip = data->chip;
 	u8 regval;
 	int ret = 0;
 
@@ -197,6 +212,7 @@ static int pca954x_probe(struct i2c_client *client,
 	int num, force, class;
 	struct i2c_mux_core *muxc;
 	struct pca954x *data;
+	const struct of_device_id *match;
 	int ret;
 
 	if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE))
@@ -226,14 +242,19 @@ static int pca954x_probe(struct i2c_client *client,
 		return -ENODEV;
 	}
 
-	data->type = id->driver_data;
+	match = of_match_device(of_match_ptr(pca954x_of_match), &client->dev);
+	if (match)
+		data->chip = of_device_get_match_data(&client->dev);
+	else
+		data->chip = &chips[id->driver_data];
+
 	data->last_chan = 0;		   /* force the first selection */
 
 	idle_disconnect_dt = of_node &&
 		of_property_read_bool(of_node, "i2c-mux-idle-disconnect");
 
 	/* Now create an adapter for each channel */
-	for (num = 0; num < chips[data->type].nchans; num++) {
+	for (num = 0; num < data->chip->nchans; num++) {
 		bool idle_disconnect_pd = false;
 
 		force = 0;			  /* dynamic adap number */
@@ -263,7 +284,7 @@ static int pca954x_probe(struct i2c_client *client,
 
 	dev_info(&client->dev,
 		 "registered %d multiplexed busses for I2C %s %s\n",
-		 num, chips[data->type].muxtype == pca954x_ismux
+		 num, data->chip->muxtype == pca954x_ismux
 				? "mux" : "switch", client->name);
 
 	return 0;
@@ -299,6 +320,7 @@ static struct i2c_driver pca954x_driver = {
 	.driver		= {
 		.name	= "pca954x",
 		.pm	= &pca954x_pm,
+		.of_match_table = of_match_ptr(pca954x_of_match),
 	},
 	.probe		= pca954x_probe,
 	.remove		= pca954x_remove,
-- 
2.1.4