[U-Boot] [PATCH 6/6] dm: Add timeline and guide for porting I2C drivers

[Heiko Schocher]

Hello Simon,

Am 23.11.2016 um 14:34 schrieb Simon Glass:
> Add a README with a brief guide to porting i2c drivers over to use driver
> model.
>
> Add a timeline also. All I2C drivers should be converted by the end
> of June 2017.
>
> Signed-off-by: Simon Glass <sjg at chromium.org>
> ---
>
>   doc/driver-model/i2c-howto.txt | 56 ++++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 56 insertions(+)
>   create mode 100644 doc/driver-model/i2c-howto.txt

Thanks!

Acked-by: Heiko Schocher <hs at denx.de>

bye,
Heiko
>
> diff --git a/doc/driver-model/i2c-howto.txt b/doc/driver-model/i2c-howto.txt
> new file mode 100644
> index 0000000..605d3ef
> --- /dev/null
> +++ b/doc/driver-model/i2c-howto.txt
> @@ -0,0 +1,56 @@
> +How to port a serial driver to driver model
> +===========================================
> +
> +Over half of the I2C drivers have been converted as at November 2016. These
> +ones remain:
> +
> +   adi_i2c
> +   davinci_i2c
> +   fti2c010
> +   ihs_i2c
> +   kona_i2c
> +   lpc32xx_i2c
> +   pca9564_i2c
> +   ppc4xx_i2c
> +   rcar_i2c
> +   sh_i2c
> +   sh_sh7734_i2c
> +   soft_i2c
> +   tsi108_i2c
> +   zynq_i2c
> +
> +The deadline for this work is the end of June 2017. If no one steps
> +forward to convert these, at some point there may come a patch to remove them!
> +
> +Here is a suggested approach for converting your I2C driver over to driver
> +model. Please feel free to update this file with your ideas and suggestions.
> +
> +- #ifdef out all your own I2C driver code (#ifndef CONFIG_DM_I2C)
> +- Define CONFIG_DM_I2C for your board, vendor or architecture
> +- If the board does not already use driver model, you need CONFIG_DM also
> +- Your board should then build, but will not work fully since there will be
> +    no I2C driver
> +- Add the U_BOOT_DRIVER piece at the end (e.g. copy tegra_i2c.c for example)
> +- Add a private struct for the driver data - avoid using static variables
> +- Implement each of the driver methods, perhaps by calling your old methods
> +- You may need to adjust the function parameters so that the old and new
> +    implementations can share most of the existing code
> +- If you convert all existing users of the driver, remove the pre-driver-model
> +    code
> +
> +In terms of patches a conversion series typically has these patches:
> +- clean up / prepare the driver for conversion
> +- add driver model code
> +- convert at least one existing board to use driver model serial
> +- (if no boards remain that don't use driver model) remove the old code
> +
> +This may be a good time to move your board to use device tree also. Mostly
> +this involves these steps:
> +
> +- define CONFIG_OF_CONTROL and CONFIG_OF_SEPARATE
> +- add your device tree files to arch/<arch>/dts
> +- update the Makefile there
> +- Add stdout-path to your /chosen device tree node if it is not already there
> +- build and get u-boot-dtb.bin so you can test it
> +- Your drivers can now use device tree
> +- For device tree in SPL, define CONFIG_SPL_OF_CONTROL
>

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