How to port an I2C 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

soft_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