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feat(fdt-wrappers): add CPU enumeration utility function 

This change adds a new utility function - `fdtw_for_each_cpu` - to
invoke a callback for every CPU node listed in a flattened device tree
(FDT) with the node identifier and the MPIDR of the core it describes.

Signed-off-by: Chris Kay <chris.kay@arm.com>
Change-Id: Iabb5c0f0c9d11928a4a7a41cdc7d1e09aadeb2bc
This commit is contained in:
Chris Kay 2021-09-28 16:06:25 +01:00
parent 1fa05dab07
commit 2d9ea36035
2 changed files with 47 additions and 0 deletions
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44
common/fdt_wrappers.c
View File

@ -572,3 +572,47 @@ uint64_t fdtw_translate_address(const void *dtb, int node,
/* Translate the local device address recursively */
return fdtw_translate_address(dtb, local_bus_node, global_address);
}
/*
* For every CPU node (`/cpus/cpu@n`) in an FDT, execute a callback passing a
* pointer to the FDT and the offset of the CPU node. If the return value of the
* callback is negative, it is treated as an error and the loop is aborted. In
* this situation, the value of the callback is returned from the function.
*
* Returns `0` on success, or a negative integer representing an error code.
*/
int fdtw_for_each_cpu(const void *dtb,
int (*callback)(const void *dtb, int node, uintptr_t mpidr))
{
int ret = 0;
int parent, node = 0;
parent = fdt_path_offset(dtb, "/cpus");
if (parent < 0) {
return parent;
}
fdt_for_each_subnode(node, dtb, parent) {
const char *name;
int len;
uintptr_t mpidr = 0U;
name = fdt_get_name(dtb, node, &len);
if (strncmp(name, "cpu@", 4) != 0) {
continue;
}
ret = fdt_get_reg_props_by_index(dtb, node, 0, &mpidr, NULL);
if (ret < 0) {
break;
}
ret = callback(dtb, node, mpidr);
if (ret < 0) {
break;
}
}
return ret;
}

3
include/common/fdt_wrappers.h
View File

@ -41,6 +41,9 @@ int fdt_get_stdout_node_offset(const void *dtb);
uint64_t fdtw_translate_address(const void *dtb, int bus_node,
uint64_t base_address);
int fdtw_for_each_cpu(const void *fdt,
int (*callback)(const void *dtb, int node, uintptr_t mpidr));
static inline uint32_t fdt_blob_size(const void *dtb)
{
const uint32_t *dtb_header = dtb;