serial-howto.rst 2.0 KB

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  1. .. SPDX-License-Identifier: GPL-2.0+
  2. How to port a serial driver to driver model
  3. ===========================================
  4. Almost all of the serial drivers have been converted as at January 2016. These
  5. ones remain:
  6. * serial_bfin.c
  7. * serial_pxa.c
  8. The deadline for this work was the end of January 2016. If no one steps
  9. forward to convert these, at some point there may come a patch to remove them!
  10. Here is a suggested approach for converting your serial driver over to driver
  11. model. Please feel free to update this file with your ideas and suggestions.
  12. - #ifdef out all your own serial driver code (#ifndef CONFIG_DM_SERIAL)
  13. - Define CONFIG_DM_SERIAL for your board, vendor or architecture
  14. - If the board does not already use driver model, you need CONFIG_DM also
  15. - Your board should then build, but will not boot since there will be no serial
  16. driver
  17. - Add the U_BOOT_DRIVER piece at the end (e.g. copy serial_s5p.c for example)
  18. - Add a private struct for the driver data - avoid using static variables
  19. - Implement each of the driver methods, perhaps by calling your old methods
  20. - You may need to adjust the function parameters so that the old and new
  21. implementations can share most of the existing code
  22. - If you convert all existing users of the driver, remove the pre-driver-model
  23. code
  24. In terms of patches a conversion series typically has these patches:
  25. - clean up / prepare the driver for conversion
  26. - add driver model code
  27. - convert at least one existing board to use driver model serial
  28. - (if no boards remain that don't use driver model) remove the old code
  29. This may be a good time to move your board to use device tree also. Mostly
  30. this involves these steps:
  31. - define CONFIG_OF_CONTROL and CONFIG_OF_SEPARATE
  32. - add your device tree files to arch/<arch>/dts
  33. - update the Makefile there
  34. - Add stdout-path to your /chosen device tree node if it is not already there
  35. - build and get u-boot-dtb.bin so you can test it
  36. - Your drivers can now use device tree
  37. - For device tree in SPL, define CONFIG_SPL_OF_CONTROL