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serial-howto.txt

serial-howto.txt 2.1 KB
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  1. How to port a serial driver to driver model
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  2. ===========================================
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  3. 

  4. About 16 of 33 serial drivers have been converted as at September 2015. It
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  5. is time for maintainers to start converting over the remaining serial drivers:
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  6. 

  7.    arm_dcc.c
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  8.    lpc32xx_hsuart.c
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  9.    mcfuart.c
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  10.    mxs_auart.c
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  11.    opencores_yanu.c
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  12.    serial_bfin.c
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  13.    serial_imx.c
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  14.    serial_lpuart.c
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  15.    serial_max3100.c
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  16.    serial_pxa.c
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  17.    serial_s3c24x0.c
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  18.    serial_sa1100.c
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  19.    serial_xuartlite.c
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  20.    usbtty.c
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  21. 

  22. You should complete this by the end of January 2016.
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  23. 

  24. Here is a suggested approach for converting your serial driver over to driver
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  25. model. Please feel free to update this file with your ideas and suggestions.
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  26. 

  27. - #ifdef out all your own serial driver code (#ifndef CONFIG_DM_SERIAL)
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  28. - Define CONFIG_DM_SERIAL for your board, vendor or architecture
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  29. - If the board does not already use driver model, you need CONFIG_DM also
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  30. - Your board should then build, but will not boot since there will be no serial
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  31.     driver
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  32. - Add the U_BOOT_DRIVER piece at the end (e.g. copy serial_s5p.c for example)
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  33. - Add a private struct for the driver data - avoid using static variables
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  34. - Implement each of the driver methods, perhaps by calling your old methods
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  35. - You may need to adjust the function parameters so that the old and new
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  36.     implementations can share most of the existing code
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  37. - If you convert all existing users of the driver, remove the pre-driver-model
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  38.     code
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  39. 

  40. In terms of patches a conversion series typically has these patches:
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  41. - clean up / prepare the driver for conversion
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  42. - add driver model code
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  43. - convert at least one existing board to use driver model serial
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  44. - (if no boards remain that don't use driver model) remove the old code
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  45. 

  46. This may be a good time to move your board to use device tree also. Mostly
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  47. this involves these steps:
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  48. 

  49. - define CONFIG_OF_CONTROL and CONFIG_OF_SEPARATE
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  50. - add your device tree files to arch/<arch>/dts
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  51. - update the Makefile there
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  52. - Add stdout-path to your /chosen device tree node if it is not already there
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  53. - build and get u-boot-dtb.bin so you can test it
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  54. - Your drivers can now use device tree
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  55. - For device tree in SPL, define CONFIG_SPL_OF_CONTROL
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