[U-Boot] [PATCH 3/3] Kconfig: i2c: add entry for driver-model software i2c
Masahiro Yamada
yamada.masahiro at socionext.com
Wed Mar 25 04:35:07 CET 2015
Hi.
2015-03-10 19:30 GMT+09:00 Przemyslaw Marczak <p.marczak at samsung.com>:
> Signed-off-by: Przemyslaw Marczak <p.marczak at samsung.com>
> Cc: Masahiro Yamada <yamada.m at jp.panasonic.com>
I am no longer working for Panasonic.
The old email address will get unavailable at the end of March.
Going forward, please use my new address, yamada.masahiro at socionext.com
>
> diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig
> index 0a52ed9..dd7eb3c 100644
> --- a/drivers/i2c/Kconfig
> +++ b/drivers/i2c/Kconfig
> @@ -13,6 +13,49 @@ config DM_I2C_COMPAT
> to convert all code for a board in a single commit. It should not
> be enabled for any board in an official release.
>
> +config DM_I2C_SOFT
> + bool "Enable Driver Model for Software I2C Driver"
> + depends on DM_I2C
> + help
> + Enable the i2c bus driver emulation by using GPIO.
Very nice!
> + The bus configuration is given by the device-tree, like below.
> +
> + /* First, define the alias number to have continuous bus numbering */
> + aliases {
> + [...]
> + i2c5 = "/i2c at 13500000";
> + i2c6 = "/soft-i2c at 1";
> + [...]
> + }
This description is not specific to this CONFIG option.
The relation between the aliases node and the sequence number
is well-documented in doc/driver-model/README.txt.
Should we repeat it here?
> + /* And next define the basic bus attributes */
> + soft-i2c at 1 {
> + #address-cells = <1>;
> + #size-cells = <0>;
> + compatible = "soft-i2c";
> + clock-frequency = <50000>;
> + /* Define the proper GPIO pins */
> + clock-pin = <&gpa0 0 GPIO_ACTIVE_HIGH>;
> + data-pin = <&gpa0 1 GPIO_ACTIVE_HIGH>;
> +
> + /* Optionally, define some driver node (bus child) */
> + somedev at 0x44 {
> + compatible = "somedev";
> + reg = <0x44>;
> + [...]
> + };
> + }
This is binding information, right?
Stuff like that is usually documented in a separate text file.
In Linux, Documentation/devicetree/bindings/i2c/
In U-boot, doc/device-tree-bindings/i2c/
> + The device can be accessed by the i2c command:
> + # i2c dev 8 (bus number set by alias)
> + # i2c probe <0x44> (address is optionally)
> + # i2c md 0x44 0x0 (dump dev registers at address 0x0)
> + # Valid chip addresses: 0x44 (success!)
> + ...
This is the usage of "i2c" command.
It is not specific to this option, either.
> + Driving the bus lines is done by dm gpio calls in the preprocessor
> + macros. Each, can be redefined by the user.
> +
> config SYS_I2C_UNIPHIER
> bool "UniPhier I2C driver"
> depends on ARCH_UNIPHIER && DM_I2C
> --
> 1.9.1
>
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--
Best Regards
Masahiro Yamada
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