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- 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
- 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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