1 How to port a serial driver to driver model
2 ===========================================
4 Over half of the I2C drivers have been converted as at November 2016. These
20 The deadline for this work is the end of June 2017. If no one steps
21 forward to convert these, at some point there may come a patch to remove them!
23 Here is a suggested approach for converting your I2C driver over to driver
24 model. Please feel free to update this file with your ideas and suggestions.
26 - #ifdef out all your own I2C driver code (#ifndef CONFIG_DM_I2C)
27 - Define CONFIG_DM_I2C for your board, vendor or architecture
28 - If the board does not already use driver model, you need CONFIG_DM also
29 - Your board should then build, but will not work fully since there will be
31 - Add the U_BOOT_DRIVER piece at the end (e.g. copy tegra_i2c.c for example)
32 - Add a private struct for the driver data - avoid using static variables
33 - Implement each of the driver methods, perhaps by calling your old methods
34 - You may need to adjust the function parameters so that the old and new
35 implementations can share most of the existing code
36 - If you convert all existing users of the driver, remove the pre-driver-model
39 In terms of patches a conversion series typically has these patches:
40 - clean up / prepare the driver for conversion
41 - add driver model code
42 - convert at least one existing board to use driver model serial
43 - (if no boards remain that don't use driver model) remove the old code
45 This may be a good time to move your board to use device tree also. Mostly
46 this involves these steps:
48 - define CONFIG_OF_CONTROL and CONFIG_OF_SEPARATE
49 - add your device tree files to arch/<arch>/dts
50 - update the Makefile there
51 - Add stdout-path to your /chosen device tree node if it is not already there
52 - build and get u-boot-dtb.bin so you can test it
53 - Your drivers can now use device tree
54 - For device tree in SPL, define CONFIG_SPL_OF_CONTROL