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   altera_jtag_uart.c
8   altera_uart.c
9   arm_dcc.c
10   lpc32xx_hsuart.c
11   mcfuart.c
12   mxs_auart.c
13   opencores_yanu.c
14   serial_bfin.c
15   serial_imx.c
16   serial_lpuart.c
17   serial_max3100.c
18   serial_pxa.c
19   serial_s3c24x0.c
20   serial_sa1100.c
21   serial_xuartlite.c
22   usbtty.c
23
24You should complete this by the end of January 2016.
25
26Here is a suggested approach for converting your serial driver over to driver
27model. Please feel free to update this file with your ideas and suggestions.
28
29- #ifdef out all your own serial driver code (#ifndef CONFIG_DM_SERIAL)
30- Define CONFIG_DM_SERIAL for your board, vendor or architecture
31- If the board does not already use driver model, you need CONFIG_DM also
32- Your board should then build, but will not boot since there will be no serial
33    driver
34- Add the U_BOOT_DRIVER piece at the end (e.g. copy serial_s5p.c for example)
35- Add a private struct for the driver data - avoid using static variables
36- Implement each of the driver methods, perhaps by calling your old methods
37- You may need to adjust the function parameters so that the old and new
38    implementations can share most of the existing code
39- If you convert all existing users of the driver, remove the pre-driver-model
40    code
41
42In terms of patches a conversion series typically has these patches:
43- clean up / prepare the driver for conversion
44- add driver model code
45- convert at least one existing board to use driver model serial
46- (if no boards remain that don't use driver model) remove the old code
47
48This may be a good time to move your board to use device tree also. Mostly
49this involves these steps:
50
51- define CONFIG_OF_CONTROL and CONFIG_OF_SEPARATE
52- add your device tree files to arch/<arch>/dts
53- update the Makefile there
54- Add stdout-path to your /chosen device tree node if it is not already there
55- build and get u-boot-dtb.bin so you can test it
56- Your drivers can now use device tree
57- For device tree in SPL, define CONFIG_SPL_OF_CONTROL
58