summaryrefslogtreecommitdiff
path: root/Documentation/i2c/instantiating-devices
diff options
context:
space:
mode:
authorGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-02-18 21:27:12 +0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-02-18 21:27:12 +0400
commit9d265649a86c6c0e4bae164a4c5ce806f0f12fc8 (patch)
treea782d3ffe0a171e540fdda19764ab81e11cb1a4c /Documentation/i2c/instantiating-devices
parent6d36b6f313738e99fc8b903697f8ecf06add29aa (diff)
parent6d0abeca3242a88cab8232e4acd7e2bf088f3bc2 (diff)
downloadlinux-9d265649a86c6c0e4bae164a4c5ce806f0f12fc8.tar.xz
Merge 3.14-rc3 into usb-next
We want the fixes in this branch as well. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation/i2c/instantiating-devices')
-rw-r--r--Documentation/i2c/instantiating-devices41
1 files changed, 39 insertions, 2 deletions
diff --git a/Documentation/i2c/instantiating-devices b/Documentation/i2c/instantiating-devices
index c70e7a7638d1..0d85ac1935b7 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 +51,43 @@ 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 1c: Declare the I2C devices via ACPI
+-------------------------------------------
+
+ACPI can also describe I2C devices. There is special documentation for this
+which is currently located at Documentation/acpi/enumeration.txt.
+
+
Method 2: Instantiate the devices explicitly
--------------------------------------------