Commit ddf67f71 authored by Maxime Ripard's avatar Maxime Ripard Committed by Tom Rini

libfdt: Add overlay application function

The device tree overlays are a good way to deal with user-modifyable
boards or boards with some kind of an expansion mechanism where we can
easily plug new board in (like the BBB, the Raspberry Pi or the CHIP).

Add a new function to merge overlays with a base device tree.
Signed-off-by: 's avatarMaxime Ripard <maxime.ripard@free-electrons.com>
parent ea7b1a21
......@@ -1740,6 +1740,36 @@ int fdt_add_subnode(void *fdt, int parentoffset, const char *name);
*/
int fdt_del_node(void *fdt, int nodeoffset);
/**
* fdt_overlay_apply - Applies a DT overlay on a base DT
* @fdt: pointer to the base device tree blob
* @fdto: pointer to the device tree overlay blob
*
* fdt_overlay_apply() will apply the given device tree overlay on the
* given base device tree.
*
* Expect the base device tree to be modified, even if the function
* returns an error.
*
* returns:
* 0, on success
* -FDT_ERR_NOSPACE, there's not enough space in the base device tree
* -FDT_ERR_NOTFOUND, the overlay points to some inexistant nodes or
* properties in the base DT
* -FDT_ERR_BADPHANDLE, the phandles in the overlay do not have the right
* magic
* -FDT_ERR_INTERNAL,
* -FDT_ERR_BADLAYOUT,
* -FDT_ERR_BADMAGIC,
* -FDT_ERR_BADOFFSET,
* -FDT_ERR_BADPATH,
* -FDT_ERR_BADVERSION,
* -FDT_ERR_BADSTRUCTURE,
* -FDT_ERR_BADSTATE,
* -FDT_ERR_TRUNCATED, standard meanings
*/
int fdt_overlay_apply(void *fdt, void *fdto);
/**********************************************************************/
/* Debugging / informational functions */
/**********************************************************************/
......
......@@ -139,6 +139,11 @@ config OF_LIBFDT
particular compatible nodes. The library operates on a flattened
version of the device tree.
config OF_LIBFDT_OVERLAY
bool "Enable the FDT library overlay support"
help
This enables the FDT library (libfdt) overlay support.
config SPL_OF_LIBFDT
bool "Enable the FDT library for SPL"
default y if SPL_OF_CONTROL
......
......@@ -15,3 +15,5 @@ obj-y += \
fdt_empty_tree.o \
fdt_addresses.o \
fdt_region.o
obj-$(CONFIG_OF_LIBFDT_OVERLAY) += fdt_overlay.o
#include "libfdt_env.h"
#include <fdt.h>
#include <libfdt.h>
#include "libfdt_internal.h"
static uint32_t overlay_get_target_phandle(const void *fdto, int fragment)
{
const uint32_t *val;
int len;
val = fdt_getprop(fdto, fragment, "target", &len);
if (!val)
return 0;
if ((*val == 0xffffffff) || (len != sizeof(*val)))
return 0xffffffff;
return fdt32_to_cpu(*val);
}
static int overlay_get_target(const void *fdt, const void *fdto,
int fragment)
{
uint32_t phandle;
const char *path;
/* Try first to do a phandle based lookup */
phandle = overlay_get_target_phandle(fdto, fragment);
if (phandle == -1)
return -FDT_ERR_BADPHANDLE;
if (phandle)
return fdt_node_offset_by_phandle(fdt, phandle);
/* And then a path based lookup */
path = fdt_getprop(fdto, fragment, "target-path", NULL);
if (!path)
return -FDT_ERR_NOTFOUND;
return fdt_path_offset(fdt, path);
}
static int overlay_phandle_add_offset(void *fdt, int node,
const char *name, uint32_t delta)
{
const uint32_t *val;
uint32_t adj_val;
int len;
val = fdt_getprop(fdt, node, name, &len);
if (!val)
return len;
if (len != sizeof(*val))
return -FDT_ERR_BADSTRUCTURE;
adj_val = fdt32_to_cpu(*val);
if ((adj_val + delta) < adj_val)
return -FDT_ERR_BADPHANDLE;
adj_val += delta;
return fdt_setprop_inplace_u32(fdt, node, name, adj_val);
}
static int overlay_adjust_node_phandles(void *fdto, int node,
uint32_t delta)
{
bool found = false;
int child;
int ret;
ret = overlay_phandle_add_offset(fdto, node, "phandle", delta);
if (ret && ret != -FDT_ERR_NOTFOUND)
return ret;
if (!ret)
found = true;
ret = overlay_phandle_add_offset(fdto, node, "linux,phandle", delta);
if (ret && ret != -FDT_ERR_NOTFOUND)
return ret;
/*
* If neither phandle nor linux,phandle have been found return
* an error.
*/
if (!found && !ret)
return ret;
fdt_for_each_subnode(fdto, child, node)
overlay_adjust_node_phandles(fdto, child, delta);
return 0;
}
static int overlay_adjust_local_phandles(void *fdto, uint32_t delta)
{
/*
* Start adjusting the phandles from the overlay root
*/
return overlay_adjust_node_phandles(fdto, 0, delta);
}
static int overlay_update_local_node_references(void *fdto,
int tree_node,
int fixup_node,
uint32_t delta)
{
int fixup_prop;
int fixup_child;
int ret;
fdt_for_each_property_offset(fixup_prop, fdto, fixup_node) {
const uint32_t *val = NULL;
uint32_t adj_val, index;
const char *name;
int fixup_len;
int tree_len;
val = fdt_getprop_by_offset(fdto, fixup_prop,
&name, &fixup_len);
if (!val)
return fixup_len;
index = fdt32_to_cpu(*val);
val = fdt_getprop(fdto, tree_node, name, &tree_len);
if (!val)
return tree_len;
/*
* The index can be unaligned.
*
* Use a memcpy for the architectures that do not
* support unaligned accesses.
*/
memcpy(&adj_val, (unsigned char *)val + index,
sizeof(uint32_t));
adj_val = fdt32_to_cpu(adj_val);
adj_val += delta;
adj_val = cpu_to_fdt32(adj_val);
ret = fdt_setprop_inplace_namelen_by_index(fdto, tree_node,
name, strlen(name),
index, &adj_val,
sizeof(adj_val));
if (ret)
return ret;
}
fdt_for_each_subnode(fdto, fixup_child, fixup_node) {
const char *fixup_child_name = fdt_get_name(fdto, fixup_child,
NULL);
int tree_child;
tree_child = fdt_subnode_offset(fdto, tree_node,
fixup_child_name);
if (tree_child < 0)
return tree_child;
ret = overlay_update_local_node_references(fdto,
tree_child,
fixup_child,
delta);
if (ret)
return ret;
}
return 0;
}
static int overlay_update_local_references(void *dto, uint32_t delta)
{
int fixups;
fixups = fdt_path_offset(dto, "/__local_fixups__");
if (fixups < 0) {
/* There's no local phandles to adjust, bail out */
if (fixups == -FDT_ERR_NOTFOUND)
return 0;
return fixups;
}
/*
* Update our local references from the root of the tree
*/
return overlay_update_local_node_references(dto, 0, fixups,
delta);
}
static int overlay_fixup_one_phandle(void *fdt, void *fdto,
int symbols_off,
const char *path, uint32_t path_len,
const char *name, uint32_t name_len,
int index, const char *label)
{
const char *symbol_path;
uint32_t phandle;
int symbol_off, fixup_off;
int prop_len;
symbol_path = fdt_getprop(fdt, symbols_off, label,
&prop_len);
if (!symbol_path)
return -FDT_ERR_NOTFOUND;
symbol_off = fdt_path_offset(fdt, symbol_path);
if (symbol_off < 0)
return symbol_off;
phandle = fdt_get_phandle(fdt, symbol_off);
if (!phandle)
return -FDT_ERR_NOTFOUND;
fixup_off = fdt_path_offset_namelen(fdto, path, path_len);
if (fixup_off < 0)
return fixup_off;
phandle = cpu_to_fdt32(phandle);
return fdt_setprop_inplace_namelen_by_index(fdto, fixup_off,
name, name_len, index,
&phandle, sizeof(phandle));
};
static int overlay_fixup_phandle(void *fdt, void *fdto, int symbols_off,
int property)
{
const char *value;
const char *label;
int len;
value = fdt_getprop_by_offset(fdto, property,
&label, &len);
if (!value)
return len;
do {
const char *prop_string = value;
const char *path, *name;
uint32_t prop_len = strlen(value);
uint32_t path_len, name_len;
char *sep, *endptr;
int index;
int ret;
path = prop_string;
sep = memchr(prop_string, ':', prop_len);
if (*sep != ':')
return -FDT_ERR_BADSTRUCTURE;
path_len = sep - path;
name = sep + 1;
sep = memchr(name, ':', prop_len);
if (*sep != ':')
return -FDT_ERR_BADSTRUCTURE;
name_len = sep - name;
index = strtoul(sep + 1, &endptr, 10);
if ((*endptr != '\0') || (endptr <= (sep + 1)))
return -FDT_ERR_BADSTRUCTURE;
len -= prop_len + 1;
value += prop_len + 1;
ret = overlay_fixup_one_phandle(fdt, fdto, symbols_off,
path, path_len, name, name_len,
index, label);
if (ret)
return ret;
} while (len > 0);
return 0;
}
static int overlay_fixup_phandles(void *dt, void *dto)
{
int fixups_off, symbols_off;
int property;
symbols_off = fdt_path_offset(dt, "/__symbols__");
fixups_off = fdt_path_offset(dto, "/__fixups__");
fdt_for_each_property_offset(property, dto, fixups_off)
overlay_fixup_phandle(dt, dto, symbols_off, property);
return 0;
}
static int apply_overlay_node(void *dt, int target,
void *dto, int fragment)
{
int property;
int node;
fdt_for_each_property_offset(property, dto, fragment) {
const char *name;
const void *prop;
int prop_len;
int ret;
prop = fdt_getprop_by_offset(dto, property, &name,
&prop_len);
if (prop_len == -FDT_ERR_NOTFOUND)
return -FDT_ERR_INTERNAL;
if (prop_len < 0)
return prop_len;
ret = fdt_setprop(dt, target, name, prop, prop_len);
if (ret)
return ret;
}
fdt_for_each_subnode(dto, node, fragment) {
const char *name = fdt_get_name(dto, node, NULL);
int nnode;
int ret;
nnode = fdt_add_subnode(dt, target, name);
if (nnode == -FDT_ERR_EXISTS)
nnode = fdt_subnode_offset(dt, target, name);
if (nnode < 0)
return nnode;
ret = apply_overlay_node(dt, nnode, dto, node);
if (ret)
return ret;
}
return 0;
}
static int overlay_merge(void *dt, void *dto)
{
int fragment;
fdt_for_each_subnode(dto, fragment, 0) {
int overlay;
int target;
int ret;
target = overlay_get_target(dt, dto, fragment);
if (target < 0)
continue;
overlay = fdt_subnode_offset(dto, fragment, "__overlay__");
if (overlay < 0)
return overlay;
ret = apply_overlay_node(dt, target, dto, overlay);
if (ret)
return ret;
}
return 0;
}
int fdt_overlay_apply(void *fdt, void *fdto)
{
uint32_t delta = fdt_get_max_phandle(fdt) + 1;
int ret;
FDT_CHECK_HEADER(fdt);
FDT_CHECK_HEADER(fdto);
ret = overlay_adjust_local_phandles(fdto, delta);
if (ret)
goto err;
ret = overlay_update_local_references(fdto, delta);
if (ret)
goto err;
ret = overlay_fixup_phandles(fdt, fdto);
if (ret)
goto err;
ret = overlay_merge(fdt, fdto);
if (ret)
goto err;
/*
* The overlay has been damaged, erase its magic.
*/
fdt_set_magic(fdto, ~0);
return 0;
err:
/*
* The overlay might have been damaged, erase its magic.
*/
fdt_set_magic(fdto, ~0);
/*
* The base device tree might have been damaged, erase its
* magic.
*/
fdt_set_magic(fdt, ~0);
return ret;
}
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