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