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Diffstat (limited to 'doc/driver-model/README.txt')
| -rw-r--r-- | doc/driver-model/README.txt | 44 |
1 files changed, 34 insertions, 10 deletions
diff --git a/doc/driver-model/README.txt b/doc/driver-model/README.txt index 0278dda4d7..3e2f622657 100644 --- a/doc/driver-model/README.txt +++ b/doc/driver-model/README.txt @@ -750,19 +750,43 @@ device pointers, but this is not currently implemented (the root device pointer is saved but not made available through the driver model API). -Things to punt for later ------------------------- +SPL Support +----------- + +Driver model can operate in SPL. Its efficient implementation and small code +size provide for a small overhead which is acceptable for all but the most +constrained systems. + +To enable driver model in SPL, define CONFIG_SPL_DM. You might want to +consider the following option also. See the main README for more details. + + - CONFIG_SYS_MALLOC_SIMPLE + - CONFIG_DM_WARN + - CONFIG_DM_DEVICE_REMOVE + - CONFIG_DM_STDIO -- SPL support - this will have to be present before many drivers can be -converted, but it seems like we can add it once we are happy with the -core implementation. -That is not to say that no thinking has gone into this - in fact there -is quite a lot there. However, getting these right is non-trivial and -there is a high cost associated with going down the wrong path. +Enabling Driver Model +--------------------- -For SPL, it may be possible to fit in a simplified driver model with only -bind and probe methods, to reduce size. +Driver model is being brought into U-Boot gradually. As each subsystems gets +support, a uclass is created and a CONFIG to enable use of driver model for +that subsystem. + +For example CONFIG_DM_SERIAL enables driver model for serial. With that +defined, the old serial support is not enabled, and your serial driver must +conform to driver model. With that undefined, the old serial support is +enabled and driver model is not available for serial. This means that when +you convert a driver, you must either convert all its boards, or provide for +the driver to be compiled both with and without driver model (generally this +is not very hard). + +See the main README for full details of the available driver model CONFIG +options. + + +Things to punt for later +------------------------ Uclasses are statically numbered at compile time. It would be possible to change this to dynamic numbering, but then we would require some sort of |