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_lpuart.c
15   serial_max3100.c
16   serial_pxa.c
17   serial_s3c24x0.c
18   serial_sa1100.c
19   serial_xuartlite.c
20   usbtty.c
21
22You should complete this by the end of January 2016.
23
24Here is a suggested approach for converting your serial driver over to driver
25model. Please feel free to update this file with your ideas and suggestions.
26
27- #ifdef out all your own serial driver code (#ifndef CONFIG_DM_SERIAL)
28- Define CONFIG_DM_SERIAL 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 boot since there will be no serial
31    driver
32- Add the U_BOOT_DRIVER piece at the end (e.g. copy serial_s5p.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
38    code
39
40In 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
45
46This may be a good time to move your board to use device tree also. Mostly
47this involves these steps:
48
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
56