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| author | Max Filippov <jcmvbkbc@gmail.com> | 2015-02-02 16:28:12 +0100 |
|---|---|---|
| committer | Wolfram Sang <wsa@the-dreams.de> | 2015-02-05 22:29:15 +0100 |
| commit | 3a33a85401ecdb0e2c01ea86d9e36a5711ce01d4 (patch) | |
| tree | f94aad5c7f9ee69d07a81db4e3fcaa1214202eb8 /Documentation | |
| parent | i2c: tegra: Maintain CPU endianness (diff) | |
| download | linux-3a33a85401ecdb0e2c01ea86d9e36a5711ce01d4.tar.xz linux-3a33a85401ecdb0e2c01ea86d9e36a5711ce01d4.zip | |
i2c: ocores: fix clock-frequency binding usage
clock-frequency property is meant to control the bus frequency for i2c bus
drivers, but it was incorrectly used to specify i2c controller input clock
frequency.
Introduce new attribute, opencores,ip-clock-frequency, that specifies i2c
controller clock frequency and make clock-frequency attribute compatible
with other i2c drivers. Maintain backwards compatibility in case
opencores,ip-clock-frequency attribute is missing.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/devicetree/bindings/i2c/i2c-ocores.txt | 18 |
1 files changed, 16 insertions, 2 deletions
diff --git a/Documentation/devicetree/bindings/i2c/i2c-ocores.txt b/Documentation/devicetree/bindings/i2c/i2c-ocores.txt index 1637c298a1b3..5bef3adf2c35 100644 --- a/Documentation/devicetree/bindings/i2c/i2c-ocores.txt +++ b/Documentation/devicetree/bindings/i2c/i2c-ocores.txt @@ -4,15 +4,29 @@ Required properties: - compatible : "opencores,i2c-ocores" or "aeroflexgaisler,i2cmst" - reg : bus address start and address range size of device - interrupts : interrupt number -- clock-frequency : frequency of bus clock in Hz +- opencores,ip-clock-frequency: frequency of the controller clock in Hz; + see the note below - #address-cells : should be <1> - #size-cells : should be <0> Optional properties: +- clock-frequency : frequency of bus clock in Hz; see the note below. + Defaults to 100 KHz when the property is not specified - reg-shift : device register offsets are shifted by this value - reg-io-width : io register width in bytes (1, 2 or 4) - regstep : deprecated, use reg-shift above +Note +clock-frequency property is meant to control the bus frequency for i2c bus +drivers, but it was incorrectly used to specify i2c controller input clock +frequency. So the following rules are set to fix this situation: +- if clock-frequency is present and opencores,ip-clock-frequency is not, + then clock-frequency specifies i2c controller clock frequency. This is + to keep backwards compatibility with setups using old DTB. i2c bus + frequency is fixed at 100 KHz. +- if opencores,ip-clock-frequency is present it specifies i2c controller + clock frequency. clock-frequency property specifies i2c bus frequency. + Example: i2c0: ocores@a0000000 { @@ -21,7 +35,7 @@ Example: compatible = "opencores,i2c-ocores"; reg = <0xa0000000 0x8>; interrupts = <10>; - clock-frequency = <20000000>; + opencores,ip-clock-frequency = <20000000>; reg-shift = <0>; /* 8 bit registers */ reg-io-width = <1>; /* 8 bit read/write */ |