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: Maxime Ripard <maxime.ripard@free-electrons.com>
This commit is contained in:
Maxime Ripard
Tom Rini
parent
ea7b1a213e
commit
ddf67f7135
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@ -1740,6 +1740,36 @@ int fdt_add_subnode(void *fdt, int parentoffset, const char *name);
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*/
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int fdt_del_node(void *fdt, int nodeoffset);
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/**
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* fdt_overlay_apply - Applies a DT overlay on a base DT
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* @fdt: pointer to the base device tree blob
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* @fdto: pointer to the device tree overlay blob
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*
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* fdt_overlay_apply() will apply the given device tree overlay on the
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* given base device tree.
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*
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* Expect the base device tree to be modified, even if the function
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* returns an error.
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*
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* returns:
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* 0, on success
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* -FDT_ERR_NOSPACE, there's not enough space in the base device tree
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* -FDT_ERR_NOTFOUND, the overlay points to some inexistant nodes or
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* properties in the base DT
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* -FDT_ERR_BADPHANDLE, the phandles in the overlay do not have the right
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* magic
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* -FDT_ERR_INTERNAL,
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* -FDT_ERR_BADLAYOUT,
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* -FDT_ERR_BADMAGIC,
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* -FDT_ERR_BADOFFSET,
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* -FDT_ERR_BADPATH,
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* -FDT_ERR_BADVERSION,
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* -FDT_ERR_BADSTRUCTURE,
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* -FDT_ERR_BADSTATE,
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* -FDT_ERR_TRUNCATED, standard meanings
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*/
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int fdt_overlay_apply(void *fdt, void *fdto);
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/**********************************************************************/
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/* Debugging / informational functions */
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/**********************************************************************/
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@ -139,6 +139,11 @@ config OF_LIBFDT
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particular compatible nodes. The library operates on a flattened
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version of the device tree.
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config OF_LIBFDT_OVERLAY
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bool "Enable the FDT library overlay support"
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help
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This enables the FDT library (libfdt) overlay support.
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config SPL_OF_LIBFDT
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bool "Enable the FDT library for SPL"
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default y if SPL_OF_CONTROL
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@ -15,3 +15,5 @@ obj-y += \
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fdt_empty_tree.o \
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fdt_addresses.o \
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fdt_region.o
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obj-$(CONFIG_OF_LIBFDT_OVERLAY) += fdt_overlay.o
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@ -0,0 +1,405 @@
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#include "libfdt_env.h"
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#include <fdt.h>
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#include <libfdt.h>
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#include "libfdt_internal.h"
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static uint32_t overlay_get_target_phandle(const void *fdto, int fragment)
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{
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const uint32_t *val;
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int len;
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val = fdt_getprop(fdto, fragment, "target", &len);
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if (!val)
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return 0;
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if ((*val == 0xffffffff) || (len != sizeof(*val)))
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return 0xffffffff;
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return fdt32_to_cpu(*val);
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}
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static int overlay_get_target(const void *fdt, const void *fdto,
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int fragment)
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{
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uint32_t phandle;
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const char *path;
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/* Try first to do a phandle based lookup */
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phandle = overlay_get_target_phandle(fdto, fragment);
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if (phandle == -1)
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return -FDT_ERR_BADPHANDLE;
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if (phandle)
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return fdt_node_offset_by_phandle(fdt, phandle);
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/* And then a path based lookup */
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path = fdt_getprop(fdto, fragment, "target-path", NULL);
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if (!path)
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return -FDT_ERR_NOTFOUND;
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return fdt_path_offset(fdt, path);
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}
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static int overlay_phandle_add_offset(void *fdt, int node,
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const char *name, uint32_t delta)
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{
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const uint32_t *val;
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uint32_t adj_val;
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int len;
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val = fdt_getprop(fdt, node, name, &len);
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if (!val)
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return len;
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if (len != sizeof(*val))
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return -FDT_ERR_BADSTRUCTURE;
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adj_val = fdt32_to_cpu(*val);
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if ((adj_val + delta) < adj_val)
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return -FDT_ERR_BADPHANDLE;
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adj_val += delta;
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return fdt_setprop_inplace_u32(fdt, node, name, adj_val);
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}
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static int overlay_adjust_node_phandles(void *fdto, int node,
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uint32_t delta)
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{
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bool found = false;
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int child;
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int ret;
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ret = overlay_phandle_add_offset(fdto, node, "phandle", delta);
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if (ret && ret != -FDT_ERR_NOTFOUND)
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return ret;
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if (!ret)
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found = true;
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ret = overlay_phandle_add_offset(fdto, node, "linux,phandle", delta);
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if (ret && ret != -FDT_ERR_NOTFOUND)
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return ret;
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/*
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* If neither phandle nor linux,phandle have been found return
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* an error.
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*/
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if (!found && !ret)
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return ret;
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fdt_for_each_subnode(fdto, child, node)
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overlay_adjust_node_phandles(fdto, child, delta);
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return 0;
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}
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static int overlay_adjust_local_phandles(void *fdto, uint32_t delta)
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{
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/*
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* Start adjusting the phandles from the overlay root
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*/
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return overlay_adjust_node_phandles(fdto, 0, delta);
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}
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static int overlay_update_local_node_references(void *fdto,
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int tree_node,
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int fixup_node,
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uint32_t delta)
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{
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int fixup_prop;
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int fixup_child;
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int ret;
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fdt_for_each_property_offset(fixup_prop, fdto, fixup_node) {
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const uint32_t *val = NULL;
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uint32_t adj_val, index;
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const char *name;
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int fixup_len;
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int tree_len;
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val = fdt_getprop_by_offset(fdto, fixup_prop,
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&name, &fixup_len);
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if (!val)
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return fixup_len;
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index = fdt32_to_cpu(*val);
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val = fdt_getprop(fdto, tree_node, name, &tree_len);
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if (!val)
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return tree_len;
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/*
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* The index can be unaligned.
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*
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* Use a memcpy for the architectures that do not
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* support unaligned accesses.
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*/
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memcpy(&adj_val, (unsigned char *)val + index,
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sizeof(uint32_t));
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adj_val = fdt32_to_cpu(adj_val);
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adj_val += delta;
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adj_val = cpu_to_fdt32(adj_val);
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ret = fdt_setprop_inplace_namelen_by_index(fdto, tree_node,
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name, strlen(name),
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index, &adj_val,
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sizeof(adj_val));
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if (ret)
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return ret;
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}
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fdt_for_each_subnode(fdto, fixup_child, fixup_node) {
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const char *fixup_child_name = fdt_get_name(fdto, fixup_child,
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NULL);
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int tree_child;
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tree_child = fdt_subnode_offset(fdto, tree_node,
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fixup_child_name);
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if (tree_child < 0)
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return tree_child;
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ret = overlay_update_local_node_references(fdto,
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tree_child,
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fixup_child,
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delta);
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if (ret)
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return ret;
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}
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return 0;
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}
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static int overlay_update_local_references(void *dto, uint32_t delta)
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{
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int fixups;
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fixups = fdt_path_offset(dto, "/__local_fixups__");
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if (fixups < 0) {
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/* There's no local phandles to adjust, bail out */
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if (fixups == -FDT_ERR_NOTFOUND)
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return 0;
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return fixups;
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}
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/*
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* Update our local references from the root of the tree
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*/
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return overlay_update_local_node_references(dto, 0, fixups,
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delta);
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}
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static int overlay_fixup_one_phandle(void *fdt, void *fdto,
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int symbols_off,
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const char *path, uint32_t path_len,
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const char *name, uint32_t name_len,
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int index, const char *label)
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{
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const char *symbol_path;
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uint32_t phandle;
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int symbol_off, fixup_off;
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int prop_len;
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symbol_path = fdt_getprop(fdt, symbols_off, label,
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&prop_len);
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if (!symbol_path)
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return -FDT_ERR_NOTFOUND;
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symbol_off = fdt_path_offset(fdt, symbol_path);
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if (symbol_off < 0)
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return symbol_off;
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phandle = fdt_get_phandle(fdt, symbol_off);
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if (!phandle)
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return -FDT_ERR_NOTFOUND;
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fixup_off = fdt_path_offset_namelen(fdto, path, path_len);
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if (fixup_off < 0)
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return fixup_off;
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phandle = cpu_to_fdt32(phandle);
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return fdt_setprop_inplace_namelen_by_index(fdto, fixup_off,
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name, name_len, index,
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&phandle, sizeof(phandle));
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};
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static int overlay_fixup_phandle(void *fdt, void *fdto, int symbols_off,
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int property)
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{
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const char *value;
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const char *label;
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int len;
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value = fdt_getprop_by_offset(fdto, property,
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&label, &len);
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if (!value)
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return len;
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do {
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const char *prop_string = value;
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const char *path, *name;
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uint32_t prop_len = strlen(value);
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uint32_t path_len, name_len;
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char *sep, *endptr;
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int index;
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int ret;
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path = prop_string;
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sep = memchr(prop_string, ':', prop_len);
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if (*sep != ':')
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return -FDT_ERR_BADSTRUCTURE;
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path_len = sep - path;
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name = sep + 1;
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sep = memchr(name, ':', prop_len);
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if (*sep != ':')
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return -FDT_ERR_BADSTRUCTURE;
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name_len = sep - name;
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index = strtoul(sep + 1, &endptr, 10);
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if ((*endptr != '\0') || (endptr <= (sep + 1)))
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return -FDT_ERR_BADSTRUCTURE;
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len -= prop_len + 1;
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value += prop_len + 1;
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ret = overlay_fixup_one_phandle(fdt, fdto, symbols_off,
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path, path_len, name, name_len,
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index, label);
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if (ret)
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return ret;
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} while (len > 0);
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return 0;
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}
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static int overlay_fixup_phandles(void *dt, void *dto)
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{
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int fixups_off, symbols_off;
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int property;
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symbols_off = fdt_path_offset(dt, "/__symbols__");
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fixups_off = fdt_path_offset(dto, "/__fixups__");
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fdt_for_each_property_offset(property, dto, fixups_off)
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overlay_fixup_phandle(dt, dto, symbols_off, property);
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return 0;
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}
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static int apply_overlay_node(void *dt, int target,
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void *dto, int fragment)
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{
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int property;
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int node;
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fdt_for_each_property_offset(property, dto, fragment) {
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const char *name;
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const void *prop;
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int prop_len;
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int ret;
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prop = fdt_getprop_by_offset(dto, property, &name,
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&prop_len);
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if (prop_len == -FDT_ERR_NOTFOUND)
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return -FDT_ERR_INTERNAL;
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if (prop_len < 0)
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return prop_len;
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ret = fdt_setprop(dt, target, name, prop, prop_len);
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if (ret)
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return ret;
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}
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fdt_for_each_subnode(dto, node, fragment) {
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const char *name = fdt_get_name(dto, node, NULL);
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int nnode;
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int ret;
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nnode = fdt_add_subnode(dt, target, name);
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if (nnode == -FDT_ERR_EXISTS)
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nnode = fdt_subnode_offset(dt, target, name);
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if (nnode < 0)
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return nnode;
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ret = apply_overlay_node(dt, nnode, dto, node);
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if (ret)
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return ret;
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}
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return 0;
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}
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static int overlay_merge(void *dt, void *dto)
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{
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int fragment;
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fdt_for_each_subnode(dto, fragment, 0) {
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int overlay;
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int target;
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int ret;
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target = overlay_get_target(dt, dto, fragment);
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if (target < 0)
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continue;
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overlay = fdt_subnode_offset(dto, fragment, "__overlay__");
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if (overlay < 0)
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return overlay;
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ret = apply_overlay_node(dt, target, dto, overlay);
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if (ret)
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return ret;
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}
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return 0;
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}
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int fdt_overlay_apply(void *fdt, void *fdto)
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{
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uint32_t delta = fdt_get_max_phandle(fdt) + 1;
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int ret;
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FDT_CHECK_HEADER(fdt);
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FDT_CHECK_HEADER(fdto);
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ret = overlay_adjust_local_phandles(fdto, delta);
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if (ret)
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goto err;
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ret = overlay_update_local_references(fdto, delta);
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if (ret)
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goto err;
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ret = overlay_fixup_phandles(fdt, fdto);
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if (ret)
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goto err;
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ret = overlay_merge(fdt, fdto);
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if (ret)
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goto err;
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/*
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* The overlay has been damaged, erase its magic.
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*/
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fdt_set_magic(fdto, ~0);
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return 0;
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err:
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/*
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* The overlay might have been damaged, erase its magic.
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*/
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fdt_set_magic(fdto, ~0);
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/*
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* The base device tree might have been damaged, erase its
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* magic.
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*/
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fdt_set_magic(fdt, ~0);
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return ret;
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}
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