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author | Wolfram Sang <wolfram@the-dreams.de> | 2012-11-13 21:16:43 +0400 |
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committer | Grant Likely <grant.likely@secretlab.ca> | 2012-11-15 19:57:07 +0400 |
commit | 16c4c52435cf8bb6e5986c14d36d93a0dd4c98df (patch) | |
tree | 5a70d9d8c31df5f20e86e9c1960e1205fe0fb9b5 /Documentation/devicetree/bindings/i2c/i2c-pxa-pci-ce4100.txt | |
parent | da63d20bfb12827dd7747a841ea27348af3abc0a (diff) | |
download | linux-16c4c52435cf8bb6e5986c14d36d93a0dd4c98df.tar.xz |
bindings: i2c: use consistent naming for i2c binding descriptions
Filenames of devictree binding documentation seems to be arbitrary and
for me it is unneeded hazzle to find the corresponding documentation for
a specific driver.
Naming the description the same as the driver is a lot easier and makes
sense to me since the driver defines the binding it understands.
Also, remove a reference in one source to the binding documentation, since path
information easily gets stale.
Signed-off-by: Wolfram Sang <wolfram@the-dreams.de>
Cc: Rob Herring <robherring2@gmail.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Diffstat (limited to 'Documentation/devicetree/bindings/i2c/i2c-pxa-pci-ce4100.txt')
-rw-r--r-- | Documentation/devicetree/bindings/i2c/i2c-pxa-pci-ce4100.txt | 93 |
1 files changed, 93 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/i2c/i2c-pxa-pci-ce4100.txt b/Documentation/devicetree/bindings/i2c/i2c-pxa-pci-ce4100.txt new file mode 100644 index 000000000000..569b16248514 --- /dev/null +++ b/Documentation/devicetree/bindings/i2c/i2c-pxa-pci-ce4100.txt @@ -0,0 +1,93 @@ +CE4100 I2C +---------- + +CE4100 has one PCI device which is described as the I2C-Controller. This +PCI device has three PCI-bars, each bar contains a complete I2C +controller. So we have a total of three independent I2C-Controllers +which share only an interrupt line. +The driver is probed via the PCI-ID and is gathering the information of +attached devices from the devices tree. +Grant Likely recommended to use the ranges property to map the PCI-Bar +number to its physical address and to use this to find the child nodes +of the specific I2C controller. This were his exact words: + + Here's where the magic happens. Each entry in + ranges describes how the parent pci address space + (middle group of 3) is translated to the local + address space (first group of 2) and the size of + each range (last cell). In this particular case, + the first cell of the local address is chosen to be + 1:1 mapped to the BARs, and the second is the + offset from be base of the BAR (which would be + non-zero if you had 2 or more devices mapped off + the same BAR) + + ranges allows the address mapping to be described + in a way that the OS can interpret without + requiring custom device driver code. + +This is an example which is used on FalconFalls: +------------------------------------------------ + i2c-controller@b,2 { + #address-cells = <2>; + #size-cells = <1>; + compatible = "pci8086,2e68.2", + "pci8086,2e68", + "pciclass,ff0000", + "pciclass,ff00"; + + reg = <0x15a00 0x0 0x0 0x0 0x0>; + interrupts = <16 1>; + + /* as described by Grant, the first number in the group of + * three is the bar number followed by the 64bit bar address + * followed by size of the mapping. The bar address + * requires also a valid translation in parents ranges + * property. + */ + ranges = <0 0 0x02000000 0 0xdffe0500 0x100 + 1 0 0x02000000 0 0xdffe0600 0x100 + 2 0 0x02000000 0 0xdffe0700 0x100>; + + i2c@0 { + #address-cells = <1>; + #size-cells = <0>; + compatible = "intel,ce4100-i2c-controller"; + + /* The first number in the reg property is the + * number of the bar + */ + reg = <0 0 0x100>; + + /* This I2C controller has no devices */ + }; + + i2c@1 { + #address-cells = <1>; + #size-cells = <0>; + compatible = "intel,ce4100-i2c-controller"; + reg = <1 0 0x100>; + + /* This I2C controller has one gpio controller */ + gpio@26 { + #gpio-cells = <2>; + compatible = "ti,pcf8575"; + reg = <0x26>; + gpio-controller; + }; + }; + + i2c@2 { + #address-cells = <1>; + #size-cells = <0>; + compatible = "intel,ce4100-i2c-controller"; + reg = <2 0 0x100>; + + gpio@26 { + #gpio-cells = <2>; + compatible = "ti,pcf8575"; + reg = <0x26>; + gpio-controller; + }; + }; + }; |