diff options
Diffstat (limited to 'drivers/of/resolver.c')
| -rw-r--r-- | drivers/of/resolver.c | 351 |
1 files changed, 351 insertions, 0 deletions
diff --git a/drivers/of/resolver.c b/drivers/of/resolver.c new file mode 100644 index 000000000..b278ab433 --- /dev/null +++ b/drivers/of/resolver.c @@ -0,0 +1,351 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Functions for dealing with DT resolution + * + * Copyright (C) 2012 Pantelis Antoniou <panto@antoniou-consulting.com> + * Copyright (C) 2012 Texas Instruments Inc. + */ + +#define pr_fmt(fmt) "OF: resolver: " fmt + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/of_device.h> +#include <linux/string.h> +#include <linux/ctype.h> +#include <linux/errno.h> +#include <linux/slab.h> + +#include "of_private.h" + +static phandle live_tree_max_phandle(void) +{ + struct device_node *node; + phandle phandle; + unsigned long flags; + + raw_spin_lock_irqsave(&devtree_lock, flags); + phandle = 0; + for_each_of_allnodes(node) { + if (node->phandle != OF_PHANDLE_ILLEGAL && + node->phandle > phandle) + phandle = node->phandle; + } + raw_spin_unlock_irqrestore(&devtree_lock, flags); + + return phandle; +} + +static void adjust_overlay_phandles(struct device_node *overlay, + int phandle_delta) +{ + struct device_node *child; + struct property *prop; + phandle phandle; + + /* adjust node's phandle in node */ + if (overlay->phandle != 0 && overlay->phandle != OF_PHANDLE_ILLEGAL) + overlay->phandle += phandle_delta; + + /* copy adjusted phandle into *phandle properties */ + for_each_property_of_node(overlay, prop) { + + if (of_prop_cmp(prop->name, "phandle") && + of_prop_cmp(prop->name, "linux,phandle")) + continue; + + if (prop->length < 4) + continue; + + phandle = be32_to_cpup(prop->value); + if (phandle == OF_PHANDLE_ILLEGAL) + continue; + + *(__be32 *)prop->value = cpu_to_be32(overlay->phandle); + } + + for_each_child_of_node(overlay, child) + adjust_overlay_phandles(child, phandle_delta); +} + +static int update_usages_of_a_phandle_reference(struct device_node *overlay, + struct property *prop_fixup, phandle phandle) +{ + struct device_node *refnode; + struct property *prop; + char *value, *cur, *end, *node_path, *prop_name, *s; + int offset, len; + int err = 0; + + value = kmemdup(prop_fixup->value, prop_fixup->length, GFP_KERNEL); + if (!value) + return -ENOMEM; + + /* prop_fixup contains a list of tuples of path:property_name:offset */ + end = value + prop_fixup->length; + for (cur = value; cur < end; cur += len + 1) { + len = strlen(cur); + + node_path = cur; + s = strchr(cur, ':'); + if (!s) { + err = -EINVAL; + goto err_fail; + } + *s++ = '\0'; + + prop_name = s; + s = strchr(s, ':'); + if (!s) { + err = -EINVAL; + goto err_fail; + } + *s++ = '\0'; + + err = kstrtoint(s, 10, &offset); + if (err) + goto err_fail; + + refnode = __of_find_node_by_full_path(of_node_get(overlay), node_path); + if (!refnode) + continue; + + for_each_property_of_node(refnode, prop) { + if (!of_prop_cmp(prop->name, prop_name)) + break; + } + of_node_put(refnode); + + if (!prop) { + err = -ENOENT; + goto err_fail; + } + + if (offset < 0 || offset + sizeof(__be32) > prop->length) { + err = -EINVAL; + goto err_fail; + } + + *(__be32 *)(prop->value + offset) = cpu_to_be32(phandle); + } + +err_fail: + kfree(value); + return err; +} + +/* compare nodes taking into account that 'name' strips out the @ part */ +static int node_name_cmp(const struct device_node *dn1, + const struct device_node *dn2) +{ + const char *n1 = kbasename(dn1->full_name); + const char *n2 = kbasename(dn2->full_name); + + return of_node_cmp(n1, n2); +} + +/* + * Adjust the local phandle references by the given phandle delta. + * + * Subtree @local_fixups, which is overlay node __local_fixups__, + * mirrors the fragment node structure at the root of the overlay. + * + * For each property in the fragments that contains a phandle reference, + * @local_fixups has a property of the same name that contains a list + * of offsets of the phandle reference(s) within the respective property + * value(s). The values at these offsets will be fixed up. + */ +static int adjust_local_phandle_references(struct device_node *local_fixups, + struct device_node *overlay, int phandle_delta) +{ + struct device_node *child, *overlay_child; + struct property *prop_fix, *prop; + int err, i, count; + unsigned int off; + + if (!local_fixups) + return 0; + + for_each_property_of_node(local_fixups, prop_fix) { + + /* skip properties added automatically */ + if (!of_prop_cmp(prop_fix->name, "name") || + !of_prop_cmp(prop_fix->name, "phandle") || + !of_prop_cmp(prop_fix->name, "linux,phandle")) + continue; + + if ((prop_fix->length % 4) != 0 || prop_fix->length == 0) + return -EINVAL; + count = prop_fix->length / sizeof(__be32); + + for_each_property_of_node(overlay, prop) { + if (!of_prop_cmp(prop->name, prop_fix->name)) + break; + } + + if (!prop) + return -EINVAL; + + for (i = 0; i < count; i++) { + off = be32_to_cpu(((__be32 *)prop_fix->value)[i]); + if ((off + 4) > prop->length) + return -EINVAL; + + be32_add_cpu(prop->value + off, phandle_delta); + } + } + + /* + * These nested loops recurse down two subtrees in parallel, where the + * node names in the two subtrees match. + * + * The roots of the subtrees are the overlay's __local_fixups__ node + * and the overlay's root node. + */ + for_each_child_of_node(local_fixups, child) { + + for_each_child_of_node(overlay, overlay_child) + if (!node_name_cmp(child, overlay_child)) { + of_node_put(overlay_child); + break; + } + + if (!overlay_child) { + of_node_put(child); + return -EINVAL; + } + + err = adjust_local_phandle_references(child, overlay_child, + phandle_delta); + if (err) { + of_node_put(child); + return err; + } + } + + return 0; +} + +/** + * of_resolve_phandles - Relocate and resolve overlay against live tree + * + * @overlay: Pointer to devicetree overlay to relocate and resolve + * + * Modify (relocate) values of local phandles in @overlay to a range that + * does not conflict with the live expanded devicetree. Update references + * to the local phandles in @overlay. Update (resolve) phandle references + * in @overlay that refer to the live expanded devicetree. + * + * Phandle values in the live tree are in the range of + * 1 .. live_tree_max_phandle(). The range of phandle values in the overlay + * also begin with at 1. Adjust the phandle values in the overlay to begin + * at live_tree_max_phandle() + 1. Update references to the phandles to + * the adjusted phandle values. + * + * The name of each property in the "__fixups__" node in the overlay matches + * the name of a symbol (a label) in the live tree. The values of each + * property in the "__fixups__" node is a list of the property values in the + * overlay that need to be updated to contain the phandle reference + * corresponding to that symbol in the live tree. Update the references in + * the overlay with the phandle values in the live tree. + * + * @overlay must be detached. + * + * Resolving and applying @overlay to the live expanded devicetree must be + * protected by a mechanism to ensure that multiple overlays are processed + * in a single threaded manner so that multiple overlays will not relocate + * phandles to overlapping ranges. The mechanism to enforce this is not + * yet implemented. + * + * Return: %0 on success or a negative error value on error. + */ +int of_resolve_phandles(struct device_node *overlay) +{ + struct device_node *child, *local_fixups, *refnode; + struct device_node *tree_symbols, *overlay_fixups; + struct property *prop; + const char *refpath; + phandle phandle, phandle_delta; + int err; + + tree_symbols = NULL; + + if (!overlay) { + pr_err("null overlay\n"); + err = -EINVAL; + goto out; + } + + if (!of_node_check_flag(overlay, OF_DETACHED)) { + pr_err("overlay not detached\n"); + err = -EINVAL; + goto out; + } + + phandle_delta = live_tree_max_phandle() + 1; + adjust_overlay_phandles(overlay, phandle_delta); + + for_each_child_of_node(overlay, local_fixups) + if (of_node_name_eq(local_fixups, "__local_fixups__")) + break; + + err = adjust_local_phandle_references(local_fixups, overlay, phandle_delta); + if (err) + goto out; + + overlay_fixups = NULL; + + for_each_child_of_node(overlay, child) { + if (of_node_name_eq(child, "__fixups__")) + overlay_fixups = child; + } + + if (!overlay_fixups) { + err = 0; + goto out; + } + + tree_symbols = of_find_node_by_path("/__symbols__"); + if (!tree_symbols) { + pr_err("no symbols in root of device tree.\n"); + err = -EINVAL; + goto out; + } + + for_each_property_of_node(overlay_fixups, prop) { + + /* skip properties added automatically */ + if (!of_prop_cmp(prop->name, "name")) + continue; + + err = of_property_read_string(tree_symbols, + prop->name, &refpath); + if (err) { + pr_err("node label '%s' not found in live devicetree symbols table\n", + prop->name); + goto out; + } + + refnode = of_find_node_by_path(refpath); + if (!refnode) { + err = -ENOENT; + goto out; + } + + phandle = refnode->phandle; + of_node_put(refnode); + + err = update_usages_of_a_phandle_reference(overlay, prop, phandle); + if (err) + break; + } + +out: + if (err) + pr_err("overlay phandle fixup failed: %d\n", err); + of_node_put(tree_symbols); + + return err; +} +EXPORT_SYMBOL_GPL(of_resolve_phandles); |