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1d149edd SG |
1 | How to port a serial driver to driver model |
2 | =========================================== | |
3 | ||
92d05e50 SG |
4 | Almost all of the serial drivers have been converted as at January 2016. These |
5 | ones remain: | |
1d149edd | 6 | |
1d149edd | 7 | arm_dcc.c |
1d149edd | 8 | mcfuart.c |
1d149edd | 9 | serial_bfin.c |
1d149edd SG |
10 | serial_pxa.c |
11 | serial_s3c24x0.c | |
1d149edd | 12 | |
92d05e50 SG |
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! | |
1d149edd SG |
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 |