doc/driver-model/serial-howto.txt

   1 How to port a serial driver to driver model
   2 ===========================================
   3
   4 Almost all of the serial drivers have been converted as at January 2016. These
   5 ones remain:
   6
   7    arm_dcc.c
   8    mcfuart.c
   9    serial_bfin.c
  10    serial_pxa.c
  11    serial_s3c24x0.c
  12
  13 The deadline for this work was the end of January 2016. If no one steps
  14 forward to convert these, at some point there may come a patch to remove them!
  15
  16 Here is a suggested approach for converting your serial driver over to driver
  17 model. Please feel free to update this file with your ideas and suggestions.
  18
  19 - #ifdef out all your own serial driver code (#ifndef CONFIG_DM_SERIAL)
  20 - Define CONFIG_DM_SERIAL for your board, vendor or architecture
  21 - If the board does not already use driver model, you need CONFIG_DM also
  22 - Your board should then build, but will not boot since there will be no serial
  23     driver
  24 - Add the U_BOOT_DRIVER piece at the end (e.g. copy serial_s5p.c for example)
  25 - Add a private struct for the driver data - avoid using static variables
  26 - Implement each of the driver methods, perhaps by calling your old methods
  27 - You may need to adjust the function parameters so that the old and new
  28     implementations can share most of the existing code
  29 - If you convert all existing users of the driver, remove the pre-driver-model
  30     code
  31
  32 In terms of patches a conversion series typically has these patches:
  33 - clean up / prepare the driver for conversion
  34 - add driver model code
  35 - convert at least one existing board to use driver model serial
  36 - (if no boards remain that don't use driver model) remove the old code
  37
  38 This may be a good time to move your board to use device tree also. Mostly
  39 this involves these steps:
  40
  41 - define CONFIG_OF_CONTROL and CONFIG_OF_SEPARATE
  42 - add your device tree files to arch/<arch>/dts
  43 - update the Makefile there
  44 - Add stdout-path to your /chosen device tree node if it is not already there
  45 - build and get u-boot-dtb.bin so you can test it
  46 - Your drivers can now use device tree
  47 - For device tree in SPL, define CONFIG_SPL_OF_CONTROL