| .. 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 |