1How to port a serial driver to driver model
2===========================================
3
4About 16 of 33 serial drivers have been converted as at September 2015. It
5is time for maintainers to start converting over the remaining serial drivers:
6
7   arm_dcc.c
8   lpc32xx_hsuart.c
9   mcfuart.c
10   mxs_auart.c
11   opencores_yanu.c
12   serial_bfin.c
13   serial_imx.c
14   serial_max3100.c
15   serial_pxa.c
16   serial_s3c24x0.c
17   serial_sa1100.c
18   serial_xuartlite.c
19   usbtty.c
20
21You should complete this by the end of January 2016.
22
23Here is a suggested approach for converting your serial driver over to driver
24model. Please feel free to update this file with your ideas and suggestions.
25
26- #ifdef out all your own serial driver code (#ifndef CONFIG_DM_SERIAL)
27- Define CONFIG_DM_SERIAL 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 boot since there will be no serial
30    driver
31- Add the U_BOOT_DRIVER piece at the end (e.g. copy serial_s5p.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
37    code
38
39In 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
44
45This may be a good time to move your board to use device tree also. Mostly
46this involves these steps:
47
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
55