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[fdt] Generalise access to "reg" property

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The "reg" property is also used by non-device nodes, such as the nodes
describing the system memory map.

Provide generalised functionality for parsing the "#address-cells",
"#size-cells", and "reg" properties.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown
2025-05-09 16:26:41 +01:00
parent 3027864f13
commit f988ec09e0
4 changed files with 141 additions and 26 deletions
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105
src/core/fdt.c
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@@ -563,6 +563,111 @@ int fdt_u32 ( struct fdt *fdt, unsigned int offset, const char *name,
return 0;
}
/**
* Get region cell size specification
*
* @v fdt Device tree
* @v offset Starting (parent) node offset
* @v regs Region cell size specification to fill in
*
* Note that #address-cells and #size-cells are defined on the
* immediate parent node, rather than on the node with the "reg"
* property itself.
*/
void fdt_reg_cells ( struct fdt *fdt, unsigned int offset,
struct fdt_reg_cells *regs ) {
int rc;
/* Read #address-cells, if present */
if ( ( rc = fdt_u32 ( fdt, offset, "#address-cells",
&regs->address_cells ) ) != 0 ) {
regs->address_cells = FDT_DEFAULT_ADDRESS_CELLS;
}
/* Read #size-cells, if present */
if ( ( rc = fdt_u32 ( fdt, offset, "#size-cells",
&regs->size_cells ) ) != 0 ) {
regs->size_cells = FDT_DEFAULT_SIZE_CELLS;
}
/* Calculate stride */
regs->stride = ( regs->address_cells + regs->size_cells );
}
/**
* Get number of regions
*
* @v fdt Device tree
* @v offset Starting node offset
* @v regs Region cell size specification
* @ret count Number of regions, or negative error
*/
int fdt_reg_count ( struct fdt *fdt, unsigned int offset,
struct fdt_reg_cells *regs ) {
struct fdt_descriptor desc;
const uint32_t *cell;
unsigned int count;
int rc;
/* Find property */
if ( ( rc = fdt_property ( fdt, offset, "reg", &desc ) ) != 0 )
return rc;
/* Determine number of regions */
count = ( desc.len / ( regs->stride * sizeof ( *cell ) ) );
return count;
}
/**
* Get region address
*
* @v fdt Device tree
* @v offset Starting node offset
* @v regs Region cell size specification
* @v index Region index
* @v address Region starting address to fill in
* @ret rc Return status code
*/
int fdt_reg_address ( struct fdt *fdt, unsigned int offset,
struct fdt_reg_cells *regs, unsigned int index,
uint64_t *address ) {
unsigned int cell = ( index * regs->stride );
int rc;
/* Read relevant portion of region array */
if ( ( rc = fdt_cells ( fdt, offset, "reg", cell, regs->address_cells,
address ) ) != 0 ) {
return rc;
}
return 0;
}
/**
* Get region size
*
* @v fdt Device tree
* @v offset Starting node offset
* @v regs Region cell size specification
* @v index Region index
* @v size Region size to fill in
* @ret rc Return status code
*/
int fdt_reg_size ( struct fdt *fdt, unsigned int offset,
struct fdt_reg_cells *regs, unsigned int index,
uint64_t *size ) {
unsigned int cell = ( ( index * regs->stride ) + regs->address_cells );
int rc;
/* Read relevant portion of region array */
if ( ( rc = fdt_cells ( fdt, offset, "reg", cell, regs->size_cells,
size ) ) != 0 ) {
return rc;
}
return 0;
}
/**
* Get MAC address from property
*