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diff --git a/doc/driver-model/serial-howto.rst b/doc/driver-model/serial-howto.rst new file mode 100644 index 0000000000..1469131124 --- /dev/null +++ b/doc/driver-model/serial-howto.rst @@ -0,0 +1,46 @@ +.. SPDX-License-Identifier: GPL-2.0+ + +How to port a serial driver to driver model +=========================================== + +Almost all of the serial drivers have been converted as at January 2016. These +ones remain: + + * serial_bfin.c + * serial_pxa.c + +The deadline for this work was the end of January 2016. If no one steps +forward to convert these, at some point there may come a patch to remove them! + +Here is a suggested approach for converting your serial driver over to driver +model. Please feel free to update this file with your ideas and suggestions. + +- #ifdef out all your own serial driver code (#ifndef CONFIG_DM_SERIAL) +- Define CONFIG_DM_SERIAL for your board, vendor or architecture +- If the board does not already use driver model, you need CONFIG_DM also +- Your board should then build, but will not boot since there will be no serial + driver +- Add the U_BOOT_DRIVER piece at the end (e.g. copy serial_s5p.c for example) +- Add a private struct for the driver data - avoid using static variables +- Implement each of the driver methods, perhaps by calling your old methods +- You may need to adjust the function parameters so that the old and new + implementations can share most of the existing code +- If you convert all existing users of the driver, remove the pre-driver-model + code + +In terms of patches a conversion series typically has these patches: +- clean up / prepare the driver for conversion +- add driver model code +- convert at least one existing board to use driver model serial +- (if no boards remain that don't use driver model) remove the old code + +This may be a good time to move your board to use device tree also. Mostly +this involves these steps: + +- define CONFIG_OF_CONTROL and CONFIG_OF_SEPARATE +- add your device tree files to arch/<arch>/dts +- update the Makefile there +- Add stdout-path to your /chosen device tree node if it is not already there +- build and get u-boot-dtb.bin so you can test it +- Your drivers can now use device tree +- For device tree in SPL, define CONFIG_SPL_OF_CONTROL |