Add a README with a brief guide to porting i2c drivers over to use driver model. Add a timeline also. All I2C drivers should be converted by the end of June 2017. Signed-off-by: Simon Glass <sjg@chromium.org> Acked-by: Heiko Schocher <hs@denx.de>master
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How to port a serial driver to driver model |
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Over half of the I2C drivers have been converted as at November 2016. These |
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ones remain: |
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adi_i2c |
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davinci_i2c |
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fti2c010 |
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ihs_i2c |
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kona_i2c |
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lpc32xx_i2c |
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pca9564_i2c |
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ppc4xx_i2c |
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rcar_i2c |
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sh_i2c |
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sh_sh7734_i2c |
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soft_i2c |
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tsi108_i2c |
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zynq_i2c |
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The deadline for this work is the end of June 2017. If no one steps |
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forward to convert these, at some point there may come a patch to remove them! |
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Here is a suggested approach for converting your I2C driver over to driver |
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model. Please feel free to update this file with your ideas and suggestions. |
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- #ifdef out all your own I2C driver code (#ifndef CONFIG_DM_I2C) |
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- Define CONFIG_DM_I2C for your board, vendor or architecture |
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- If the board does not already use driver model, you need CONFIG_DM also |
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- Your board should then build, but will not work fully since there will be |
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no I2C driver |
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- Add the U_BOOT_DRIVER piece at the end (e.g. copy tegra_i2c.c for example) |
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- Add a private struct for the driver data - avoid using static variables |
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- Implement each of the driver methods, perhaps by calling your old methods |
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- You may need to adjust the function parameters so that the old and new |
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implementations can share most of the existing code |
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- If you convert all existing users of the driver, remove the pre-driver-model |
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code |
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In terms of patches a conversion series typically has these patches: |
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- clean up / prepare the driver for conversion |
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- add driver model code |
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- convert at least one existing board to use driver model serial |
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- (if no boards remain that don't use driver model) remove the old code |
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This may be a good time to move your board to use device tree also. Mostly |
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this involves these steps: |
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- define CONFIG_OF_CONTROL and CONFIG_OF_SEPARATE |
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- add your device tree files to arch/<arch>/dts |
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- update the Makefile there |
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- Add stdout-path to your /chosen device tree node if it is not already there |
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- build and get u-boot-dtb.bin so you can test it |
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- Your drivers can now use device tree |
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- For device tree in SPL, define CONFIG_SPL_OF_CONTROL |
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