| Message ID | 1392026654-5343-2-git-send-email-wsa@the-dreams.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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
> 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!
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!
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 --------------------------------------------
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(-)