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dm: i2c: dts: Support an offset-len device tree property

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Since U-Boot can support different offset lengths (0-4 bytes), add a device
tree property to specify this. This avoids hard-coding it in the driver.

Signed-off-by: Simon Glass <sjg@chromium.org>
This commit is contained in:
Simon Glass 2015-01-26 20:29:37 -07:00
parent 189d80166b
commit 7132b9fd68
2 changed files with 30 additions and 1 deletions
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28
doc/device-tree-bindings/i2c/i2c.txt Normal file
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@ -0,0 +1,28 @@
U-Boot I2C
----------
U-Boot's I2C model has the concept of an offset within a chip (I2C target
device). The offset can be up to 4 bytes long, but is normally 1 byte,
meaning that offsets from 0 to 255 are supported by the chip. This often
corresponds to register numbers.
Apart from the controller-specific I2C bindings, U-Boot supports a special
property which allows the chip offset length to be selected.
Optional properties:
- u-boot,i2c-offset-len - length of chip offset in bytes. If omitted the
default value of 1 is used.
Example
-------
i2c4: i2c@12ca0000 {
cros-ec@1e {
reg = <0x1e>;
compatible = "google,cros-ec";
i2c-max-frequency = <100000>;
u-boot,i2c-offset-len = <0>;
ec-interrupt = <&gpx1 6 GPIO_ACTIVE_LOW>;
};
};

3
drivers/i2c/i2c-uclass.c
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@ -420,7 +420,8 @@ int i2c_deblock(struct udevice *bus)
int i2c_chip_ofdata_to_platdata(const void *blob, int node,
struct dm_i2c_chip *chip)
{
chip->offset_len = 1; /* default */
chip->offset_len = fdtdec_get_int(gd->fdt_blob, node,
"u-boot,i2c-offset-len", 1);
chip->flags = 0;
chip->chip_addr = fdtdec_get_int(gd->fdt_blob, node, "reg", -1);
if (chip->chip_addr == -1) {