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Simon Glass12c420c2015-11-20 10:48:47 -07001How to port a serial driver to driver model
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Simon Glass90f437f2016-01-31 09:16:17 -07004Almost all of the serial drivers have been converted as at January 2016. These
5ones remain:
Simon Glass12c420c2015-11-20 10:48:47 -07006
Simon Glass12c420c2015-11-20 10:48:47 -07007 serial_bfin.c
Simon Glass12c420c2015-11-20 10:48:47 -07008 serial_pxa.c
Simon Glass12c420c2015-11-20 10:48:47 -07009
Simon Glass90f437f2016-01-31 09:16:17 -070010The deadline for this work was the end of January 2016. If no one steps
11forward to convert these, at some point there may come a patch to remove them!
Simon Glass12c420c2015-11-20 10:48:47 -070012
13Here is a suggested approach for converting your serial driver over to driver
14model. Please feel free to update this file with your ideas and suggestions.
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16- #ifdef out all your own serial driver code (#ifndef CONFIG_DM_SERIAL)
17- Define CONFIG_DM_SERIAL for your board, vendor or architecture
18- If the board does not already use driver model, you need CONFIG_DM also
19- Your board should then build, but will not boot since there will be no serial
20 driver
21- Add the U_BOOT_DRIVER piece at the end (e.g. copy serial_s5p.c for example)
22- Add a private struct for the driver data - avoid using static variables
23- Implement each of the driver methods, perhaps by calling your old methods
24- You may need to adjust the function parameters so that the old and new
25 implementations can share most of the existing code
26- If you convert all existing users of the driver, remove the pre-driver-model
27 code
28
29In terms of patches a conversion series typically has these patches:
30- clean up / prepare the driver for conversion
31- add driver model code
32- convert at least one existing board to use driver model serial
33- (if no boards remain that don't use driver model) remove the old code
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35This may be a good time to move your board to use device tree also. Mostly
36this involves these steps:
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38- define CONFIG_OF_CONTROL and CONFIG_OF_SEPARATE
39- add your device tree files to arch/<arch>/dts
40- update the Makefile there
41- Add stdout-path to your /chosen device tree node if it is not already there
42- build and get u-boot-dtb.bin so you can test it
43- Your drivers can now use device tree
44- For device tree in SPL, define CONFIG_SPL_OF_CONTROL