[PATCH 01/17] Documentation: i2c: describe devicetree method for instantiating devices

[PATCH 01/17] Documentation: i2c: describe devicetree method for instantiating devices

[Wolfram Sang]

Signed-off-by: Wolfram Sang <wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org>
Cc: devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Cc: linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
---

 Documentation/i2c/instantiating-devices | 34 +++++++++++++++++++++++++++++++--
 1 file changed, 32 insertions(+), 2 deletions(-)

diff --git a/Documentation/i2c/instantiating-devices b/Documentation/i2c/instantiating-devices
index c70e7a7..6df095a 100644
--- a/Documentation/i2c/instantiating-devices
+++ b/Documentation/i2c/instantiating-devices
@@ -8,8 +8,8 @@ reason, the kernel code must instantiate I2C devices explicitly. There are
 several ways to achieve this, depending on the context and requirements.
 
 
-Method 1: Declare the I2C devices by bus number
------------------------------------------------
+Method 1a: Declare the I2C devices by bus number
+------------------------------------------------
 
 This method is appropriate when the I2C bus is a system bus as is the case
 for many embedded systems. On such systems, each I2C bus has a number
@@ -51,6 +51,36 @@ The devices will be automatically unbound and destroyed when the I2C bus
 they sit on goes away (if ever.)
 
 
+Method 1b: Declare the I2C devices via devicetree
+-------------------------------------------------
+
+This method has the same implications as method 1a. The declaration of I2C
+devices is here done via devicetree as subnodes of the master controller.
+
+Example:
+
+	i2c1: i2c@400a0000 {
+		/* ... master properties skipped ... */
+		clock-frequency = <100000>;
+
+		flash@50 {
+			compatible = "atmel,24c256";
+			reg = <0x50>;
+		};
+
+		pca9532: gpio@60 {
+			compatible = "nxp,pca9532";
+			gpio-controller;
+			#gpio-cells = <2>;
+			reg = <0x60>;
+		};
+	};
+
+Here, two devices are attached to the bus using a speed of 100kHz. For
+additional properties which might be needed to set up the device, please refer
+to its devicetree documentation in Documentation/devicetree/bindings/.
+
+
 Method 2: Instantiate the devices explicitly
 --------------------------------------------
 
-- 
1.8.5.1

Re: [PATCH 01/17] Documentation: i2c: describe devicetree method for instantiating devices

[linux]

Quoting Wolfram Sang <wsa@the-dreams.de>:

> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
> Cc: devicetree@vger.kernel.org
> Cc: linux-arm-kernel@lists.infradead.org
> ---
>
>  Documentation/i2c/instantiating-devices | 34  
> +++++++++++++++++++++++++++++++--
>  1 file changed, 32 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/i2c/instantiating-devices  
> b/Documentation/i2c/instantiating-devices
> index c70e7a7..6df095a 100644
> --- a/Documentation/i2c/instantiating-devices
> +++ b/Documentation/i2c/instantiating-devices
> @@ -8,8 +8,8 @@ reason, the kernel code must instantiate I2C devices  
> explicitly. There are
>  several ways to achieve this, depending on the context and requirements.
>
>
> -Method 1: Declare the I2C devices by bus number
> ------------------------------------------------
> +Method 1a: Declare the I2C devices by bus number
> +------------------------------------------------
>
>  This method is appropriate when the I2C bus is a system bus as is the case
>  for many embedded systems. On such systems, each I2C bus has a number
> @@ -51,6 +51,36 @@ The devices will be automatically unbound and  
> destroyed when the I2C bus
>  they sit on goes away (if ever.)
>
>
> +Method 1b: Declare the I2C devices via devicetree
> +-------------------------------------------------
> +

Hi Wolfram,

There is now also a means to instantiate I2C devices through
ACPI. This is documented in Documentation/acpi/enumeration.txt.

Might be worthwhile to reference it from instantiating-devices.
I guess that would be a separate patch though.

Thanks,
Guenter

Re: [PATCH 01/17] Documentation: i2c: describe devicetree method for instantiating devices

[Wolfram Sang]

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> There is now also a means to instantiate I2C devices through
> ACPI. This is documented in Documentation/acpi/enumeration.txt.
> 
> Might be worthwhile to reference it from instantiating-devices.
> I guess that would be a separate patch though.

Yes, it would. Thanks for the pointer!


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Re: [PATCH 01/17] Documentation: i2c: describe devicetree method for instantiating devices

[Wolfram Sang]

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On Mon, Feb 10, 2014 at 11:03:55AM +0100, Wolfram Sang wrote:
> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
> Cc: devicetree@vger.kernel.org
> Cc: linux-arm-kernel@lists.infradead.org

Applied to for-current, thanks!


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