diff options
| -rw-r--r-- | Documentation/devicetree/dynamic-resolution-notes.txt | 25 | ||||
| -rw-r--r-- | drivers/of/Kconfig | 3 | ||||
| -rw-r--r-- | drivers/of/Makefile | 1 | ||||
| -rw-r--r-- | drivers/of/resolver.c | 336 | ||||
| -rw-r--r-- | include/linux/of.h | 3 |
5 files changed, 368 insertions, 0 deletions
diff --git a/Documentation/devicetree/dynamic-resolution-notes.txt b/Documentation/devicetree/dynamic-resolution-notes.txt new file mode 100644 index 000000000000..083d23262abe --- /dev/null +++ b/Documentation/devicetree/dynamic-resolution-notes.txt @@ -0,0 +1,25 @@ +Device Tree Dynamic Resolver Notes +---------------------------------- + +This document describes the implementation of the in-kernel +Device Tree resolver, residing in drivers/of/resolver.c and is a +companion document to Documentation/devicetree/dt-object-internal.txt[1] + +How the resolver works +---------------------- + +The resolver is given as an input an arbitrary tree compiled with the +proper dtc option and having a /plugin/ tag. This generates the +appropriate __fixups__ & __local_fixups__ nodes as described in [1]. + +In sequence the resolver works by the following steps: + +1. Get the maximum device tree phandle value from the live tree + 1. +2. Adjust all the local phandles of the tree to resolve by that amount. +3. Using the __local__fixups__ node information adjust all local references + by the same amount. +4. For each property in the __fixups__ node locate the node it references + in the live tree. This is the label used to tag the node. +5. Retrieve the phandle of the target of the fixup. +6. For each fixup in the property locate the node:property:offset location + and replace it with the phandle value. diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig index 5160c4eb73c2..6b81a36f6420 100644 --- a/drivers/of/Kconfig +++ b/drivers/of/Kconfig @@ -79,4 +79,7 @@ config OF_RESERVED_MEM help Helpers to allow for reservation of memory regions +config OF_RESOLVE + bool + endmenu # OF diff --git a/drivers/of/Makefile b/drivers/of/Makefile index 2b6a7b129d10..ca9209ce50cd 100644 --- a/drivers/of/Makefile +++ b/drivers/of/Makefile @@ -13,6 +13,7 @@ obj-$(CONFIG_OF_PCI) += of_pci.o obj-$(CONFIG_OF_PCI_IRQ) += of_pci_irq.o obj-$(CONFIG_OF_MTD) += of_mtd.o obj-$(CONFIG_OF_RESERVED_MEM) += of_reserved_mem.o +obj-$(CONFIG_OF_RESOLVE) += resolver.o CFLAGS_fdt.o = -I$(src)/../../scripts/dtc/libfdt CFLAGS_fdt_address.o = -I$(src)/../../scripts/dtc/libfdt diff --git a/drivers/of/resolver.c b/drivers/of/resolver.c new file mode 100644 index 000000000000..aed7959f800d --- /dev/null +++ b/drivers/of/resolver.c @@ -0,0 +1,336 @@ +/* + * Functions for dealing with DT resolution + * + * Copyright (C) 2012 Pantelis Antoniou <panto@antoniou-consulting.com> + * Copyright (C) 2012 Texas Instruments Inc. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * version 2 as published by the Free Software Foundation. + */ + +#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/string.h> +#include <linux/slab.h> + +/* illegal phandle value (set when unresolved) */ +#define OF_PHANDLE_ILLEGAL 0xdeadbeef + +/** + * Find a node with the give full name by recursively following any of + * the child node links. + */ +static struct device_node *__of_find_node_by_full_name(struct device_node *node, + const char *full_name) +{ + struct device_node *child, *found; + + if (node == NULL) + return NULL; + + /* check */ + if (of_node_cmp(node->full_name, full_name) == 0) + return node; + + for_each_child_of_node(node, child) { + found = __of_find_node_by_full_name(child, full_name); + if (found != NULL) + return found; + } + + return NULL; +} + +/* + * Find live tree's maximum phandle value. + */ +static phandle of_get_tree_max_phandle(void) +{ + struct device_node *node; + phandle phandle; + unsigned long flags; + + /* now search recursively */ + 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; +} + +/* + * Adjust a subtree's phandle values by a given delta. + * Makes sure not to just adjust the device node's phandle value, + * but modify the phandle properties values as well. + */ +static void __of_adjust_tree_phandles(struct device_node *node, + int phandle_delta) +{ + struct device_node *child; + struct property *prop; + phandle phandle; + + /* first adjust the node's phandle direct value */ + if (node->phandle != 0 && node->phandle != OF_PHANDLE_ILLEGAL) + node->phandle += phandle_delta; + + /* now adjust phandle & linux,phandle values */ + for_each_property_of_node(node, prop) { + + /* only look for these two */ + if (of_prop_cmp(prop->name, "phandle") != 0 && + of_prop_cmp(prop->name, "linux,phandle") != 0) + continue; + + /* must be big enough */ + if (prop->length < 4) + continue; + + /* read phandle value */ + phandle = be32_to_cpup(prop->value); + if (phandle == OF_PHANDLE_ILLEGAL) /* unresolved */ + continue; + + /* adjust */ + *(uint32_t *)prop->value = cpu_to_be32(node->phandle); + } + + /* now do the children recursively */ + for_each_child_of_node(node, child) + __of_adjust_tree_phandles(child, phandle_delta); +} + +static int __of_adjust_phandle_ref(struct device_node *node, struct property *rprop, int value, bool is_delta) +{ + phandle phandle; + struct device_node *refnode; + struct property *sprop; + char *propval, *propcur, *propend, *nodestr, *propstr, *s; + int offset, propcurlen; + int err = 0; + + /* make a copy */ + propval = kmalloc(rprop->length, GFP_KERNEL); + if (!propval) { + pr_err("%s: Could not copy value of '%s'\n", + __func__, rprop->name); + return -ENOMEM; + } + memcpy(propval, rprop->value, rprop->length); + + propend = propval + rprop->length; + for (propcur = propval; propcur < propend; propcur += propcurlen + 1) { + propcurlen = strlen(propcur); + + nodestr = propcur; + s = strchr(propcur, ':'); + if (!s) { + pr_err("%s: Illegal symbol entry '%s' (1)\n", + __func__, propcur); + err = -EINVAL; + goto err_fail; + } + *s++ = '\0'; + + propstr = s; + s = strchr(s, ':'); + if (!s) { + pr_err("%s: Illegal symbol entry '%s' (2)\n", + __func__, (char *)rprop->value); + err = -EINVAL; + goto err_fail; + } + + *s++ = '\0'; + err = kstrtoint(s, 10, &offset); + if (err != 0) { + pr_err("%s: Could get offset '%s'\n", + __func__, (char *)rprop->value); + goto err_fail; + } + + /* look into the resolve node for the full path */ + refnode = __of_find_node_by_full_name(node, nodestr); + if (!refnode) { + pr_warn("%s: Could not find refnode '%s'\n", + __func__, (char *)rprop->value); + continue; + } + + /* now find the property */ + for_each_property_of_node(refnode, sprop) { + if (of_prop_cmp(sprop->name, propstr) == 0) + break; + } + + if (!sprop) { + pr_err("%s: Could not find property '%s'\n", + __func__, (char *)rprop->value); + err = -ENOENT; + goto err_fail; + } + + phandle = is_delta ? be32_to_cpup(sprop->value + offset) + value : value; + *(__be32 *)(sprop->value + offset) = cpu_to_be32(phandle); + } + +err_fail: + kfree(propval); + return err; +} + +/* + * Adjust the local phandle references by the given phandle delta. + * Assumes the existances of a __local_fixups__ node at the root + * of the tree. Does not take any devtree locks so make sure you + * call this on a tree which is at the detached state. + */ +static int __of_adjust_tree_phandle_references(struct device_node *node, + int phandle_delta) +{ + struct device_node *child; + struct property *rprop; + int err; + + /* locate the symbols & fixups nodes on resolve */ + for_each_child_of_node(node, child) + if (of_node_cmp(child->name, "__local_fixups__") == 0) + break; + + /* no local fixups */ + if (!child) + return 0; + + /* find the local fixups property */ + for_each_property_of_node(child, rprop) { + /* skip properties added automatically */ + if (of_prop_cmp(rprop->name, "name") == 0) + continue; + + err = __of_adjust_phandle_ref(node, rprop, phandle_delta, true); + if (err) + return err; + } + + return 0; +} + +/** + * of_resolve - Resolve the given node against the live tree. + * + * @resolve: Node to resolve + * + * Perform dynamic Device Tree resolution against the live tree + * to the given node to resolve. This depends on the live tree + * having a __symbols__ node, and the resolve node the __fixups__ & + * __local_fixups__ nodes (if needed). + * The result of the operation is a resolve node that it's contents + * are fit to be inserted or operate upon the live tree. + * Returns 0 on success or a negative error value on error. + */ +int of_resolve_phandles(struct device_node *resolve) +{ + struct device_node *child, *refnode; + struct device_node *root_sym, *resolve_sym, *resolve_fix; + struct property *rprop; + const char *refpath; + phandle phandle, phandle_delta; + int err; + + /* the resolve node must exist, and be detached */ + if (!resolve || !of_node_check_flag(resolve, OF_DETACHED)) + return -EINVAL; + + /* first we need to adjust the phandles */ + phandle_delta = of_get_tree_max_phandle() + 1; + __of_adjust_tree_phandles(resolve, phandle_delta); + err = __of_adjust_tree_phandle_references(resolve, phandle_delta); + if (err != 0) + return err; + + root_sym = NULL; + resolve_sym = NULL; + resolve_fix = NULL; + + /* this may fail (if no fixups are required) */ + root_sym = of_find_node_by_path("/__symbols__"); + + /* locate the symbols & fixups nodes on resolve */ + for_each_child_of_node(resolve, child) { + + if (!resolve_sym && + of_node_cmp(child->name, "__symbols__") == 0) + resolve_sym = child; + + if (!resolve_fix && + of_node_cmp(child->name, "__fixups__") == 0) + resolve_fix = child; + + /* both found, don't bother anymore */ + if (resolve_sym && resolve_fix) + break; + } + + /* we do allow for the case where no fixups are needed */ + if (!resolve_fix) { + err = 0; /* no error */ + goto out; + } + + /* we need to fixup, but no root symbols... */ + if (!root_sym) { + err = -EINVAL; + goto out; + } + + for_each_property_of_node(resolve_fix, rprop) { + + /* skip properties added automatically */ + if (of_prop_cmp(rprop->name, "name") == 0) + continue; + + err = of_property_read_string(root_sym, + rprop->name, &refpath); + if (err != 0) { + pr_err("%s: Could not find symbol '%s'\n", + __func__, rprop->name); + goto out; + } + + refnode = of_find_node_by_path(refpath); + if (!refnode) { + pr_err("%s: Could not find node by path '%s'\n", + __func__, refpath); + err = -ENOENT; + goto out; + } + + phandle = refnode->phandle; + of_node_put(refnode); + + pr_debug("%s: %s phandle is 0x%08x\n", + __func__, rprop->name, phandle); + + err = __of_adjust_phandle_ref(resolve, rprop, phandle, false); + if (err) + break; + } + +out: + /* NULL is handled by of_node_put as NOP */ + of_node_put(root_sym); + + return err; +} +EXPORT_SYMBOL_GPL(of_resolve_phandles); diff --git a/include/linux/of.h b/include/linux/of.h index 6c4363b8ddc3..6545e7aec7bb 100644 --- a/include/linux/of.h +++ b/include/linux/of.h @@ -863,4 +863,7 @@ static inline int of_changeset_update_property(struct of_changeset *ocs, } #endif +/* CONFIG_OF_RESOLVE api */ +extern int of_resolve_phandles(struct device_node *tree); + #endif /* _LINUX_OF_H */ |