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fdtdec: Implement carveout support functions

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The fdtdec_get_carveout() and fdtdec_set_carveout() function can be used
to read a carveout from a given node or add a carveout to a given node
using the standard device tree bindings (involving reserved-memory nodes
and the memory-region property).

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>
This commit is contained in:
Thierry Reding
2019-03-21 19:10:03 +01:00
committed by Simon Glass
parent c9222a08b3
commit 16523ac790
2 changed files with 168 additions and 0 deletions
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81
include/fdtdec.h
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@@ -1069,6 +1069,8 @@ int fdtdec_set_phandle(void *blob, int node, uint32_t phandle);
* The phandle returned from the function call can be used to reference this
* reserved memory region from other nodes.
*
* See fdtdec_set_carveout() for a more elaborate example.
*
* @param blob FDT blob
* @param basename base name of the node to create
* @param carveout information about the carveout region
@@ -1079,6 +1081,85 @@ int fdtdec_add_reserved_memory(void *blob, const char *basename,
const struct fdt_memory *carveout,
uint32_t *phandlep);
/**
* fdtdec_get_carveout() - reads a carveout from an FDT
*
* Reads information about a carveout region from an FDT. The carveout is a
* referenced by its phandle that is read from a given property in a given
* node.
*
* @param blob FDT blob
* @param node name of a node
* @param name name of the property in the given node that contains
* the phandle for the carveout
* @param index index of the phandle for which to read the carveout
* @param carveout return location for the carveout information
* @return 0 on success or a negative error code on failure
*/
int fdtdec_get_carveout(const void *blob, const char *node, const char *name,
unsigned int index, struct fdt_memory *carveout);
/**
* fdtdec_set_carveout() - sets a carveout region for a given node
*
* Sets a carveout region for a given node. If a reserved-memory node already
* exists for the carveout, the phandle for that node will be reused. If no
* such node exists, a new one will be created and a phandle to it stored in
* a specified property of the given node.
*
* As an example, consider the following code snippet:
*
* const char *node = "/host1x@50000000/dc@54240000";
* struct fdt_memory fb = {
* .start = 0x92cb3000,
* .end = 0x934b2fff,
* };
*
* fdtdec_set_carveout(fdt, node, "memory-region", 0, "framebuffer", &fb);
*
* dc@54200000 is a display controller and was set up by the bootloader to
* scan out the framebuffer specified by "fb". This would cause the following
* reserved memory region to be added:
*
* reserved-memory {
* #address-cells = <0x00000002>;
* #size-cells = <0x00000002>;
* ranges;
*
* framebuffer@92cb3000 {
* reg = <0x00000000 0x92cb3000 0x00000000 0x00800000>;
* phandle = <0x0000004d>;
* };
* };
*
* A "memory-region" property will also be added to the node referenced by the
* offset parameter.
*
* host1x@50000000 {
* ...
*
* dc@54240000 {
* ...
* memory-region = <0x0000004d>;
* ...
* };
*
* ...
* };
*
* @param blob FDT blob
* @param node name of the node to add the carveout to
* @param prop_name name of the property in which to store the phandle of
* the carveout
* @param index index of the phandle to store
* @param name base name of the reserved-memory node to create
* @param carveout information about the carveout to add
* @return 0 on success or a negative error code on failure
*/
int fdtdec_set_carveout(void *blob, const char *node, const char *prop_name,
unsigned int index, const char *name,
const struct fdt_memory *carveout);
/**
* Set up the device tree ready for use
*/