1How to port a serial driver to driver model
2===========================================
3
4Almost all of the serial drivers have been converted as at January 2016. These
5ones remain:
6
7   arm_dcc.c
8   mcfuart.c
9   serial_bfin.c
10   serial_pxa.c
11   serial_s3c24x0.c
12
13The deadline for this work was the end of January 2016. If no one steps
14forward to convert these, at some point there may come a patch to remove them!
15
16Here is a suggested approach for converting your serial driver over to driver
17model. 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
32In 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
38This may be a good time to move your board to use device tree also. Mostly
39this 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
48