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author | Wolfram Sang <wsa@the-dreams.de> | 2014-02-10 11:03:55 +0100 |
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committer | Wolfram Sang <wsa@the-dreams.de> | 2014-02-15 19:46:29 +0100 |
commit | aeca0fe62ac19217cb8158a0c5f6f74e3b8d304b (patch) | |
tree | 273a11bf3c94901c8fbc751f14e3893237adad0a /Documentation/i2c | |
parent | 79970db213344b4a4034645db5ebfc31571f3fa3 (diff) | |
download | linux-aeca0fe62ac19217cb8158a0c5f6f74e3b8d304b.tar.gz linux-aeca0fe62ac19217cb8158a0c5f6f74e3b8d304b.tar.bz2 linux-aeca0fe62ac19217cb8158a0c5f6f74e3b8d304b.zip |
Documentation: i2c: describe devicetree method for instantiating devices
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'Documentation/i2c')
-rw-r--r-- | Documentation/i2c/instantiating-devices | 34 |
1 files changed, 32 insertions, 2 deletions
diff --git a/Documentation/i2c/instantiating-devices b/Documentation/i2c/instantiating-devices index c70e7a7638d1..6df095a6071e 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 -------------------------------------------- |