|
@@ -64,17 +64,24 @@ strictly necessary. Notable problems include:
|
|
|
normally also supports device tree it must use #ifdef to separate
|
|
|
out this code, since the structures are only available in SPL.
|
|
|
|
|
|
+ - Correct relations between nodes are not implemented. This means that
|
|
|
+ parent/child relations (like bus device iteration) do not work yet.
|
|
|
+ Some phandles (those that are recognised as such) are converted into
|
|
|
+ a pointer to platform data. This pointer can potentially be used to
|
|
|
+ access the referenced device (by searching for the pointer value).
|
|
|
+ This feature is not yet implemented, however.
|
|
|
+
|
|
|
|
|
|
How it works
|
|
|
------------
|
|
|
|
|
|
-The feature is enabled by CONFIG SPL_OF_PLATDATA. This is only available
|
|
|
-in SPL and should be tested with:
|
|
|
+The feature is enabled by CONFIG OF_PLATDATA. This is only available in
|
|
|
+SPL/TPL and should be tested with:
|
|
|
|
|
|
- #if CONFIG_IS_ENABLED(SPL_OF_PLATDATA)
|
|
|
+ #if CONFIG_IS_ENABLED(OF_PLATDATA)
|
|
|
|
|
|
A new tool called 'dtoc' converts a device tree file either into a set of
|
|
|
-struct declarations, one for each compatible node, or a set of
|
|
|
+struct declarations, one for each compatible node, and a set of
|
|
|
U_BOOT_DEVICE() declarations along with the actual platform data for each
|
|
|
device. As an example, consider this MMC node:
|
|
|
|
|
@@ -156,6 +163,13 @@ This avoids the code overhead of converting the device tree data to
|
|
|
platform data in the driver. The ofdata_to_platdata() method should
|
|
|
therefore do nothing in such a driver.
|
|
|
|
|
|
+Note that for the platform data to be matched with a driver, the 'name'
|
|
|
+property of the U_BOOT_DEVICE() declaration has to match a driver declared
|
|
|
+via U_BOOT_DRIVER(). This effectively means that a U_BOOT_DRIVER() with a
|
|
|
+'name' corresponding to the devicetree 'compatible' string (after converting
|
|
|
+it to a valid name for C) is needed, so a dedicated driver is required for
|
|
|
+each 'compatible' string.
|
|
|
+
|
|
|
Where a node has multiple compatible strings, a #define is used to make them
|
|
|
equivalent, e.g.:
|
|
|
|
|
@@ -165,8 +179,8 @@ equivalent, e.g.:
|
|
|
Converting of-platdata to a useful form
|
|
|
---------------------------------------
|
|
|
|
|
|
-Of course it would be possible use the of-platdata directly in your driver
|
|
|
-whenever configuration information is required. However this meands that the
|
|
|
+Of course it would be possible to use the of-platdata directly in your driver
|
|
|
+whenever configuration information is required. However this means that the
|
|
|
driver will not be able to support device tree, since the of-platdata
|
|
|
structure is not available when device tree is used. It would make no sense
|
|
|
to use this structure if device tree were available, since the structure has
|
|
@@ -282,11 +296,6 @@ prevents them being used inadvertently. All usage must be bracketed with
|
|
|
The dt-platdata.c file contains the device declarations and is is built in
|
|
|
spl/dt-platdata.c.
|
|
|
|
|
|
-Some phandles (thsoe that are recognised as such) are converted into
|
|
|
-points to platform data. This pointer can potentially be used to access the
|
|
|
-referenced device (by searching for the pointer value). This feature is not
|
|
|
-yet implemented, however.
|
|
|
-
|
|
|
The beginnings of a libfdt Python module are provided. So far this only
|
|
|
implements a subset of the features.
|
|
|
|