On Sunday 09 August 2015 02:03 AM, Wolfram Sang wrote:
From: Wolfram Sang <wsa+rene...@sang-engineering.com>

Start a new file which describes the generic bindings used for I2C with
device tree. So we have a central place to look for them, increase
visibility of them, and hopefully reduce the amount of custom properties
introduced.

Signed-off-by: Wolfram Sang <wsa+rene...@sang-engineering.com>
---
  Documentation/devicetree/bindings/i2c/i2c.txt | 33 +++++++++++++++++++++++++++
  1 file changed, 33 insertions(+)
  create mode 100644 Documentation/devicetree/bindings/i2c/i2c.txt

diff --git a/Documentation/devicetree/bindings/i2c/i2c.txt 
b/Documentation/devicetree/bindings/i2c/i2c.txt
new file mode 100644
index 00000000000000..1175efed4a41b5
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/i2c.txt
@@ -0,0 +1,33 @@
+Generic device tree bindings for I2C busses
+===========================================
+
+This document describes generic bindings which can be used to describe I2C
+busses in a device tree.
+
+Required properties
+-------------------
+
+- #address-cells  - should be <1>. Read more about addresses below.
+- #size-cells     - should be <0>.
+- compatible      - name of I2C bus controller following generic names
+                   recommended practice.
+
+For other required properties e.g. to describe register sets, interrupts,
+clocks, etc. check the binding documentation of the specific driver.
+
+The cells properties above define that an address of children of an I2C bus
+are described by a single value. This is usually a 7 bit address. However,
+flags can be attached to the address. I2C_TEN_BIT_ADDRESS is used to mark a 10
+bit address. It is needed to avoid the ambiguity between e.g. a 7 bit address
+of 0x50 and a 10 bit address of 0x050 which, in theory, can be on the same bus.
+Another flag is I2C_OWN_SLAVE_ADDRESS to mark addresses on which we listen to
+be devices ourselves.
+
+Optional properties
+-------------------
+
+These properties may not be supported by all drivers. However, if a driver
+wants to support one of the below features, it should adapt the bindings below.
+
+- clock-frequency      - frequency of bus clock in Hz
+- wakeup-source                - device can be used as a wakeup source.


Thanks for the patch and it looks good to me.

Shouldn't we also update/add other generic optional properties?
For example,

 - i2c-sclk-low-time-ns
 - i2c-sclk-high-time-ns
 - etc...


We need to consolidate all such generic properties in here.

Thanks,
Vaibhav
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