Introduce DT overlay support. Using this functionality it is possible to dynamically overlay a part of the kernel's tree with another tree that's been dynamically loaded. It is also possible to remove node and properties.
Signed-off-by: Pantelis Antoniou <pa...@antoniou-consulting.com> --- Documentation/devicetree/overlay-notes.txt | 179 +++++++ drivers/of/Kconfig | 10 + drivers/of/Makefile | 1 + drivers/of/overlay.c | 831 +++++++++++++++++++++++++++++ include/linux/of.h | 107 ++++ 5 files changed, 1128 insertions(+) create mode 100644 Documentation/devicetree/overlay-notes.txt create mode 100644 drivers/of/overlay.c diff --git a/Documentation/devicetree/overlay-notes.txt b/Documentation/devicetree/overlay-notes.txt new file mode 100644 index 0000000..5289cbb --- /dev/null +++ b/Documentation/devicetree/overlay-notes.txt @@ -0,0 +1,179 @@ +Device Tree Overlay Notes +------------------------- + +This document describes the implementation of the in-kernel +device tree overlay functionality residing in drivers/of/overlay.c and is a +companion document to Documentation/devicetree/dt-object-internal.txt[1] & +Documentation/devicetree/dynamic-resolution-notes.txt[2] + +How overlays work +----------------- + +A Device Tree's overlay purpose is to modify the kernel's live tree, and +have the modification affecting the state of the the kernel in a way that +is reflecting the changes. +Since the kernel mainly deals with devices, any new device node that result +in an active device should have it created while if the device node is either +disabled or removed all together, the affected device should be deregistered. + +Lets take an example where we have a foo board with the following base tree +which is taken from [1]. + +---- foo.dts ----------------------------------------------------------------- + /* FOO platform */ + / { + compatible = "corp,foo"; + + /* shared resources */ + res: res { + }; + + /* On chip peripherals */ + ocp: ocp { + /* peripherals that are always instantiated */ + peripheral1 { ... }; + } + }; +---- foo.dts ----------------------------------------------------------------- + +The overlay bar.dts, when loaded (and resolved as described in [2]) should + +---- bar.dts ----------------------------------------------------------------- +/plugin/; /* allow undefined label references and record them */ +/ { + .... /* various properties for loader use; i.e. part id etc. */ + fragment@0 { + target = <&ocp>; + __overlay__ { + /* bar peripheral */ + bar { + compatible = "corp,bar"; + ... /* various properties and child nodes */ + } + }; + }; +}; +---- bar.dts ----------------------------------------------------------------- + +result in foo+bar.dts + +---- foo+bar.dts ------------------------------------------------------------- + /* FOO platform + bar peripheral */ + / { + compatible = "corp,foo"; + + /* shared resources */ + res: res { + }; + + /* On chip peripherals */ + ocp: ocp { + /* peripherals that are always instantiated */ + peripheral1 { ... }; + + /* bar peripheral */ + bar { + compatible = "corp,bar"; + ... /* various properties and child nodes */ + } + } + }; +---- foo+bar.dts ------------------------------------------------------------- + +As a result of the the overlay, a new device node (bar) has been created +so a bar platform device will be registered and if a matching device driver +is loaded the device will be created as expected. + +Overlay in-kernel API +--------------------- + +The steps typically required to get an overlay to work are as follows: + +1. Use of_build_overlay_info() to create an array of initialized and +ready to use of_overlay_info structures. +2. Call of_overlay() to apply the overlays declared in the array. +3. If the overlay needs to be removed, call of_overlay_revert(). +4. Finally release the memory taken by the overlay info array by +of_free_overlay_info(). + +/** + * of_build_overlay_info - Build an overlay info array + * @tree: Device node containing all the overlays + * @cntp: Pointer to where the overlay info count will be help + * @ovinfop: Pointer to the pointer of an overlay info structure. + * + * Helper function that given a tree containing overlay information, + * allocates and builds an overlay info array containing it, ready + * for use using of_overlay. + * + * Returns 0 on success with the @cntp @ovinfop pointers valid, + * while on error a negative error value is returned. + */ +int of_build_overlay_info(struct device_node *tree, + int *cntp, struct of_overlay_info **ovinfop); + +/** + * of_free_overlay_info - Free an overlay info array + * @count: Number of of_overlay_info's + * @ovinfo_tab: Array of overlay_info's to free + * + * Releases the memory of a previously allocate ovinfo array + * by of_build_overlay_info. + * Returns 0, or an error if the arguments are bogus. + */ +int of_free_overlay_info(int count, struct of_overlay_info *ovinfo_tab); + +/** + * of_overlay - Apply @count overlays pointed at by @ovinfo_tab + * @count: Number of of_overlay_info's + * @ovinfo_tab: Array of overlay_info's to apply + * + * Applies the overlays given, while handling all error conditions + * appropriately. Either the operation succeeds, or if it fails the + * live tree is reverted to the state before the attempt. + * Returns 0, or an error if the overlay attempt failed. + */ +int of_overlay(int count, struct of_overlay_info *ovinfo_tab); + +/** + * of_overlay_revert - Revert a previously applied overlay + * @count: Number of of_overlay_info's + * @ovinfo_tab: Array of overlay_info's to apply + * + * Revert a previous overlay. The state of the live tree + * is reverted to the one before the overlay. + * Returns 0, or an error if the overlay table is not given. + */ +int of_overlay_revert(int count, struct of_overlay_info *ovinfo_tab); + +Overlay DTS Format +------------------ + +The DTS of an overlay should have the following format: + +{ + /* ignored properties by the overlay */ + + fragment@0 { /* first child node */ + target=<phandle>; /* target of the overlay */ + __overlay__ { + property-a; /* add property-a to the target */ + -property-b; /* remove property-b from target */ + node-a { /* add to an existing, or create a node-a */ + ... + }; + -node-b { /* remove an existing node-b */ + ... + }; + }; + } + fragment@1 { /* second child node */ + ... + }; + /* more fragments follow */ +} + +It should be noted that the DT overlay format described is the one expected +by the of_build_overlay_info() function, which is a helper function. There +is nothing stopping someone coming up with his own DTS format and that will +end up filling in the fields of the of_overlay_info array. diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig index f9a6193..964a1c2 100644 --- a/drivers/of/Kconfig +++ b/drivers/of/Kconfig @@ -92,4 +92,14 @@ config OF_RESOLVE Enable OF dynamic resolution support. This allows you to load Device Tree object fragments are run time. +config OF_OVERLAY + bool "OF overlay support" + depends on OF + select OF_DYNAMIC + select OF_DEVICE + select OF_RESOLVE + help + OpenFirmware overlay support. Allows you to modify on runtime the + live tree using overlays. + endmenu # OF diff --git a/drivers/of/Makefile b/drivers/of/Makefile index 9a809c9..bc06912 100644 --- a/drivers/of/Makefile +++ b/drivers/of/Makefile @@ -12,3 +12,4 @@ 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_RESOLVE) += resolver.o +obj-$(CONFIG_OF_OVERLAY) += overlay.o diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c new file mode 100644 index 0000000..f65c3a3 --- /dev/null +++ b/drivers/of/overlay.c @@ -0,0 +1,831 @@ +/* + * Functions for working with device tree overlays + * + * Copyright (C) 2012 Pantelis Antoniou <pa...@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> +#include <linux/err.h> + +/** + * Apply a single overlay node recursively. + * + * Property or node names that start with '-' signal that + * the property/node is to be removed. + * + * All the property notifiers are appropriately called. + * Note that the in case of an error the target node is left + * in a inconsistent state. Error recovery should be performed + * by recording the modification using the of notifiers. + */ +static int of_overlay_apply_one(struct device_node *target, + const struct device_node *overlay) +{ + const char *pname, *cname; + struct device_node *child, *tchild; + struct property *prop, *propn, *tprop; + int remove; + char *full_name; + const char *suffix; + int ret; + + /* sanity checks */ + if (target == NULL || overlay == NULL) + return -EINVAL; + + for_each_property_of_node(overlay, prop) { + + /* don't touch, 'name' */ + if (of_prop_cmp(prop->name, "name") == 0) + continue; + + /* default is add */ + remove = 0; + pname = prop->name; + if (*pname == '-') { /* skip, - notes removal */ + pname++; + remove = 1; + propn = NULL; + } else { + propn = __of_copy_property(prop, + GFP_KERNEL); + if (propn == NULL) + return -ENOMEM; + } + + tprop = of_find_property(target, pname, NULL); + + /* found? */ + if (tprop != NULL) { + if (propn != NULL) + ret = of_update_property(target, propn); + else + ret = of_remove_property(target, tprop); + } else { + if (propn != NULL) + ret = of_add_property(target, propn); + else + ret = 0; + } + if (ret != 0) + return ret; + } + + __for_each_child_of_node(overlay, child) { + + /* default is add */ + remove = 0; + cname = child->name; + if (*cname == '-') { /* skip, - notes removal */ + cname++; + remove = 1; + } + + /* special case for nodes with a suffix */ + suffix = strrchr(child->full_name, '@'); + if (suffix != NULL) { + cname = kbasename(child->full_name); + WARN_ON(cname == NULL); /* sanity check */ + if (cname == NULL) + continue; + if (*cname == '-') + cname++; + } + + tchild = of_get_child_by_name(target, cname); + if (tchild != NULL) { + + if (!remove) { + + /* apply overlay recursively */ + ret = of_overlay_apply_one(tchild, child); + of_node_put(tchild); + + if (ret != 0) + return ret; + + } else { + + ret = of_detach_node(tchild); + of_node_put(tchild); + } + + } else { + + if (!remove) { + full_name = kasprintf(GFP_KERNEL, "%s/%s", + target->full_name, cname); + if (full_name == NULL) + return -ENOMEM; + + /* create empty tree as a target */ + tchild = __of_create_empty_node(cname, + child->type, full_name, + child->phandle, GFP_KERNEL); + + /* free either way */ + kfree(full_name); + + if (tchild == NULL) + return -ENOMEM; + + /* point to parent */ + tchild->parent = target; + + ret = of_attach_node(tchild); + if (ret != 0) + return ret; + + /* apply the overlay */ + ret = of_overlay_apply_one(tchild, child); + if (ret != 0) { + __of_free_tree(tchild); + return ret; + } + } + } + } + + return 0; +} + +/** + * Lookup an overlay device entry + */ +struct of_overlay_device_entry *of_overlay_device_entry_lookup( + struct of_overlay_info *ovinfo, struct device_node *node) +{ + struct of_overlay_device_entry *re; + + /* no need for locks, we're under the ovinfo->lock */ + list_for_each_entry(re, &ovinfo->de_list, node) { + if (re->np == node) + return re; + } + return NULL; +} + +/** + * Add an overlay log entry + */ +static int of_overlay_log_entry_entry_add(struct of_overlay_info *ovinfo, + unsigned long action, struct device_node *dn, + struct property *prop) +{ + struct of_overlay_log_entry *le; + + /* check */ + if (ovinfo == NULL || dn == NULL) + return -EINVAL; + + le = kzalloc(sizeof(*le), GFP_KERNEL); + if (le == NULL) { + pr_err("%s: Failed to allocate\n", __func__); + return -ENOMEM; + } + + /* get a reference to the node */ + le->action = action; + le->np = of_node_get(dn); + le->prop = prop; + + if (action == OF_RECONFIG_UPDATE_PROPERTY && prop) + le->old_prop = of_find_property(dn, prop->name, NULL); + + list_add_tail(&le->node, &ovinfo->le_list); + + return 0; +} + +/** + * Add an overlay device entry + */ +static void of_overlay_device_entry_entry_add(struct of_overlay_info *ovinfo, + struct device_node *node, struct platform_device *pdev, + int state) +{ + struct of_overlay_device_entry *re; + int fresh; + + /* check */ + if (ovinfo == NULL) + return; + + fresh = 0; + re = of_overlay_device_entry_lookup(ovinfo, node); + if (re == NULL) { + re = kzalloc(sizeof(*re), GFP_KERNEL); + if (re == NULL) { + pr_err("%s: Failed to allocate\n", __func__); + return; + } + fresh = 1; + } + + if (re->np == NULL) + re->np = of_node_get(node); + if (re->pdev == NULL) + re->pdev = of_dev_get(pdev); + re->state = state; + + if (fresh) + list_add_tail(&re->node, &ovinfo->de_list); +} + +/** + * Overlay OF notifier + * + * Called every time there's a property/node modification + * Every modification causes a log entry addition, while + * any modification that causes a node's state to change + * from/to disabled to/from enabled causes a device entry + * addition. + */ +static int of_overlay_notify(struct notifier_block *nb, + unsigned long action, void *arg) +{ +#ifdef DEBUG + char *propstr = NULL, *spropstr = NULL; +#endif + struct of_overlay_info *ovinfo; + struct device_node *node; + struct property *prop, *sprop, *cprop; + struct of_prop_reconfig *pr; + struct platform_device *pdev; + int state; + int err = 0; + + ovinfo = container_of(nb, struct of_overlay_info, notifier); + + /* prep vars */ + switch (action) { + case OF_RECONFIG_ATTACH_NODE: + case OF_RECONFIG_DETACH_NODE: + node = arg; + if (node == NULL) + return notifier_from_errno(-EINVAL); + prop = NULL; +#ifdef DEBUG + propstr = NULL; +#endif + break; + case OF_RECONFIG_ADD_PROPERTY: + case OF_RECONFIG_REMOVE_PROPERTY: + case OF_RECONFIG_UPDATE_PROPERTY: + pr = arg; + if (pr == NULL) + return notifier_from_errno(-EINVAL); + node = pr->dn; + if (node == NULL) + return notifier_from_errno(-EINVAL); + prop = pr->prop; + if (prop == NULL) + return notifier_from_errno(-EINVAL); +#ifdef DEBUG + propstr = __of_dump_prop(prop); +#endif + break; + default: + return notifier_from_errno(0); + } + + /* add to the log */ + err = of_overlay_log_entry_entry_add(ovinfo, action, node, prop); + if (err != 0) + return notifier_from_errno(err); + +#ifdef DEBUG + switch (action) { + case OF_RECONFIG_ATTACH_NODE: + pr_debug("ATTACH_NODE: %s\n", node->full_name); + break; + case OF_RECONFIG_DETACH_NODE: + pr_debug("DETACH_NODE: %s\n", node->full_name); + break; + case OF_RECONFIG_ADD_PROPERTY: + pr_debug("ADD_PROP: %s %s%s\n", node->full_name, + prop->name, propstr); + break; + case OF_RECONFIG_REMOVE_PROPERTY: + pr_debug("REMOVE_PROP: %s %s%s\n", node->full_name, + prop->name, propstr); + break; + case OF_RECONFIG_UPDATE_PROPERTY: + sprop = of_find_property(node, prop->name, NULL); + if (sprop) + spropstr = __of_dump_prop(sprop); + pr_debug("UPDATE_PROP: %s '%s%s' -> '%s%s'\n", node->full_name, + prop->name, spropstr, + prop->name, propstr); + break; + + } + + /* NULL is fine */ + kfree(propstr); + kfree(spropstr); +#endif + + /* come up with the device entry (if any) */ + pdev = NULL; + state = 0; + + /* determine the state the node will end up */ + switch (action) { + case OF_RECONFIG_ATTACH_NODE: + /* we demand that a compatible node is present */ + state = of_find_property(node, "compatible", NULL) && + of_device_is_available(node); + break; + case OF_RECONFIG_DETACH_NODE: + state = 0; + pdev = of_find_device_by_node(node); + break; + case OF_RECONFIG_ADD_PROPERTY: + case OF_RECONFIG_REMOVE_PROPERTY: + case OF_RECONFIG_UPDATE_PROPERTY: + /* either one cause a change in state */ + if (strcmp(prop->name, "status") != 0 && + strcmp(prop->name, "compatible") != 0) + return notifier_from_errno(0); + + if (strcmp(prop->name, "status") == 0) { + /* status */ + cprop = of_find_property(node, "compatible", NULL); + sprop = action != OF_RECONFIG_REMOVE_PROPERTY ? + prop : NULL; + } else { + /* compatible */ + sprop = of_find_property(node, "status", NULL); + cprop = action != OF_RECONFIG_REMOVE_PROPERTY ? + prop : NULL; + } + + state = cprop && cprop->length > 0 && + (!sprop || (sprop->length > 0 && + (strcmp(sprop->value, "okay") == 0 || + strcmp(sprop->value, "ok") == 0))); + break; + + default: + return notifier_from_errno(0); + } + + if (state == 0) + pdev = of_find_device_by_node(node); + + of_overlay_device_entry_entry_add(ovinfo, node, pdev, state); + + return notifier_from_errno(err); +} + +/** + * Prepare for the overlay, for now it just registers the + * notifier. + */ +static int of_overlay_prep_one(struct of_overlay_info *ovinfo) +{ + int err; + + err = of_reconfig_notifier_register(&ovinfo->notifier); + if (err != 0) { + pr_err("%s: failed to register notifier for '%s'\n", + __func__, ovinfo->target->full_name); + return err; + } + return 0; +} + +/** + * Revert one overlay + * Either due to an error, or due to normal overlay removal. + * Using the log entries, we revert any change to the live tree. + * In the same manner, using the device entries we enable/disable + * the platform devices appropriately. + */ +static void of_overlay_revert_one(struct of_overlay_info *ovinfo) +{ + struct of_overlay_device_entry *re, *ren; + struct of_overlay_log_entry *le, *len; + struct property *prop, **propp; + struct platform_device *pdev, *parent_pdev; + int ret; + unsigned long flags; + + if (!ovinfo || !ovinfo->target || !ovinfo->overlay) + return; + + pr_debug("%s: Reverting overlay on '%s'\n", __func__, + ovinfo->target->full_name); + + /* overlay applied correctly, now create/destroy pdevs */ + list_for_each_entry_safe_reverse(re, ren, &ovinfo->de_list, node) { + + if (!re->state) { + + parent_pdev = of_find_device_by_node(re->np->parent); + + pr_debug("%s: creating new platform device " + "new_node='%s' %p\n", + __func__, re->np->full_name, re->np); + + pdev = of_platform_device_create(re->np, NULL, + parent_pdev ? &parent_pdev->dev : NULL); + of_dev_put(parent_pdev); + + if (pdev == NULL) { + pr_warn("%s: Failed to create platform device " + "for '%s'\n", + __func__, re->np->full_name); + } + + } else { + + if (re->pdev) { + pr_debug("%s: removing pdev %s\n", __func__, + dev_name(&re->pdev->dev)); + platform_device_unregister(re->pdev); + } + } + + of_node_put(re->np); + + list_del(&re->node); + + kfree(re); + } + + list_for_each_entry_safe_reverse(le, len, &ovinfo->le_list, node) { + + ret = 0; + switch (le->action) { + case OF_RECONFIG_ATTACH_NODE: + pr_debug("Reverting ATTACH_NODE %s\n", + le->np->full_name); + ret = of_detach_node(le->np); + break; + + case OF_RECONFIG_DETACH_NODE: + pr_debug("Reverting DETACH_NODE %s\n", + le->np->full_name); + ret = of_attach_node(le->np); + break; + + case OF_RECONFIG_ADD_PROPERTY: + pr_debug("Reverting ADD_PROPERTY %s %s\n", + le->np->full_name, le->prop->name); + ret = of_remove_property(le->np, le->prop); + break; + + case OF_RECONFIG_REMOVE_PROPERTY: + case OF_RECONFIG_UPDATE_PROPERTY: + + pr_debug("Reverting %s_PROPERTY %s %s\n", + le->action == OF_RECONFIG_REMOVE_PROPERTY ? + "REMOVE" : "UPDATE", + le->np->full_name, le->prop->name); + + /* property is possibly on deadprops (avoid alloc) */ + write_lock_irqsave(&devtree_lock, flags); + prop = le->action == OF_RECONFIG_REMOVE_PROPERTY ? + le->prop : le->old_prop; + propp = &le->np->deadprops; + while (*propp != NULL) { + if (*propp == prop) + break; + propp = &(*propp)->next; + } + if (*propp != NULL) { + /* remove it from deadprops */ + (*propp)->next = prop->next; + write_unlock_irqrestore(&devtree_lock, flags); + } else { + write_unlock_irqrestore(&devtree_lock, flags); + /* not found, just make a copy */ + prop = __of_copy_property(prop, GFP_KERNEL); + if (prop == NULL) { + pr_err("%s: Failed to copy property\n", + __func__); + break; + } + } + + if (le->action == OF_RECONFIG_REMOVE_PROPERTY) + ret = of_add_property(le->np, prop); + else + ret = of_update_property(le->np, prop); + break; + + default: + /* nothing */ + break; + } + + if (ret != 0) + pr_err("%s: revert on node %s Failed!\n", + __func__, le->np->full_name); + + of_node_put(le->np); + + list_del(&le->node); + + kfree(le); + } +} + +/** + * Perform the post overlay work. + * + * We unregister the notifier, and in the case on an error we + * revert the overlay. + * If the overlay applied correctly, we iterare over the device entries + * and create/destroy the platform devices appropriately. + */ +static int of_overlay_post_one(struct of_overlay_info *ovinfo, int err) +{ + struct of_overlay_device_entry *re, *ren; + struct platform_device *pdev, *parent_pdev; + + of_reconfig_notifier_unregister(&ovinfo->notifier); + + if (err != 0) { + /* revert this (possible partially applied) overlay */ + of_overlay_revert_one(ovinfo); + return 0; + } + + /* overlay applied correctly, now create/destroy pdevs */ + list_for_each_entry_safe(re, ren, &ovinfo->de_list, node) { + + if (re->state) { + + parent_pdev = of_find_device_by_node(re->np->parent); + + pr_debug("%s: creating new platform device " + "new_node='%s' %p\n", + __func__, re->np->full_name, re->np); + + pdev = of_platform_device_create(re->np, NULL, + parent_pdev ? &parent_pdev->dev : NULL); + of_dev_put(parent_pdev); + + if (pdev == NULL) { + pr_warn("%s: Failed to create platform device " + "for '%s'\n", + __func__, re->np->full_name); + } + + /* keep it around */ + re->pdev = pdev; + + } else { + + if (re->pdev) { + platform_device_unregister(re->pdev); + } + } + } + + return 0; +} + +/** + * of_overlay - Apply @count overlays pointed at by @ovinfo_tab + * @count: Number of of_overlay_info's + * @ovinfo_tab: Array of overlay_info's to apply + * + * Applies the overlays given, while handling all error conditions + * appropriately. Either the operation succeeds, or if it fails the + * live tree is reverted to the state before the attempt. + * Returns 0, or an error if the overlay attempt failed. + */ +int of_overlay(int count, struct of_overlay_info *ovinfo_tab) +{ + struct of_overlay_info *ovinfo; + int i, err; + + if (!ovinfo_tab) + return -EINVAL; + + /* first we apply the overlays atomically */ + for (i = 0; i < count; i++) { + + ovinfo = &ovinfo_tab[i]; + + mutex_lock(&ovinfo->lock); + + err = of_overlay_prep_one(ovinfo); + if (err == 0) + err = of_overlay_apply_one(ovinfo->target, + ovinfo->overlay); + of_overlay_post_one(ovinfo, err); + + mutex_unlock(&ovinfo->lock); + + if (err != 0) { + pr_err("%s: overlay failed '%s'\n", + __func__, ovinfo->target->full_name); + goto err_fail; + } + } + + return 0; + +err_fail: + while (--i >= 0) { + ovinfo = &ovinfo_tab[i]; + + mutex_lock(&ovinfo->lock); + of_overlay_revert_one(ovinfo); + mutex_unlock(&ovinfo->lock); + } + + return err; +} + +/** + * of_overlay_revert - Revert a previously applied overlay + * @count: Number of of_overlay_info's + * @ovinfo_tab: Array of overlay_info's to apply + * + * Revert a previous overlay. The state of the live tree + * is reverted to the one before the overlay. + * Returns 0, or an error if the overlay table is not given. + */ +int of_overlay_revert(int count, struct of_overlay_info *ovinfo_tab) +{ + struct of_overlay_info *ovinfo; + int i; + + if (!ovinfo_tab) + return -EINVAL; + + /* revert the overlays in reverse */ + for (i = count - 1; i >= 0; i--) { + + ovinfo = &ovinfo_tab[i]; + + mutex_lock(&ovinfo->lock); + of_overlay_revert_one(ovinfo); + mutex_unlock(&ovinfo->lock); + + } + + return 0; +} + +/** + * of_init_overlay_info - Initialize a single of_overlay_info structure + * @ovinfo: Pointer to the overlay info structure to initialize + * + * Initialize a single overlay info structure. + */ +void of_init_overlay_info(struct of_overlay_info *ovinfo) +{ + memset(ovinfo, 0, sizeof(ovinfo)); + mutex_init(&ovinfo->lock); + INIT_LIST_HEAD(&ovinfo->de_list); + INIT_LIST_HEAD(&ovinfo->le_list); + + ovinfo->notifier.notifier_call = of_overlay_notify; +} + +/** + * of_fill_overlay_info - Fill an overlay info structure + * @info_node: Device node containing the overlay + * @ovinfo: Pointer to the overlay info structure to fill + * + * Fills an overlay info structure with the overlay information + * from a device node. This device node must have a target property + * which contains a phandle of the overlay target node, and an + * __overlay__ child node which has the overlay contents. + * Both ovinfo->target & ovinfo->overlay have their references taken. + * + * Returns 0 on success, or a negative error value. + */ +int of_fill_overlay_info(struct device_node *info_node, + struct of_overlay_info *ovinfo) +{ + u32 val; + int ret; + + if (!info_node || !ovinfo) + return -EINVAL; + + ret = of_property_read_u32(info_node, "target", &val); + if (ret != 0) + goto err_fail; + + ovinfo->target = of_find_node_by_phandle(val); + if (ovinfo->target == NULL) + goto err_fail; + + ovinfo->overlay = of_get_child_by_name(info_node, "__overlay__"); + if (ovinfo->overlay == NULL) + goto err_fail; + + return 0; + +err_fail: + of_node_put(ovinfo->target); + of_node_put(ovinfo->overlay); + + memset(ovinfo, 0, sizeof(*ovinfo)); + return -EINVAL; +} + +/** + * of_build_overlay_info - Build an overlay info array + * @tree: Device node containing all the overlays + * @cntp: Pointer to where the overlay info count will be help + * @ovinfop: Pointer to the pointer of an overlay info structure. + * + * Helper function that given a tree containing overlay information, + * allocates and builds an overlay info array containing it, ready + * for use using of_overlay. + * + * Returns 0 on success with the @cntp @ovinfop pointers valid, + * while on error a negative error value is returned. + */ +int of_build_overlay_info(struct device_node *tree, + int *cntp, struct of_overlay_info **ovinfop) +{ + struct device_node *node; + struct of_overlay_info *ovinfo; + int cnt, err; + + if (tree == NULL || cntp == NULL || ovinfop == NULL) + return -EINVAL; + + /* worst case; every child is a node */ + cnt = 0; + for_each_child_of_node(tree, node) + cnt++; + + ovinfo = kzalloc(cnt * sizeof(*ovinfo), GFP_KERNEL); + if (ovinfo == NULL) + return -ENOMEM; + + cnt = 0; + for_each_child_of_node(tree, node) { + + of_init_overlay_info(&ovinfo[cnt]); + err = of_fill_overlay_info(node, &ovinfo[cnt]); + if (err == 0) + cnt++; + } + + /* if nothing filled, return error */ + if (cnt == 0) { + kfree(ovinfo); + return -ENODEV; + } + + *cntp = cnt; + *ovinfop = ovinfo; + + return 0; +} + +/** + * of_free_overlay_info - Free an overlay info array + * @count: Number of of_overlay_info's + * @ovinfo_tab: Array of overlay_info's to free + * + * Releases the memory of a previously allocate ovinfo array + * by of_build_overlay_info. + * Returns 0, or an error if the arguments are bogus. + */ +int of_free_overlay_info(int count, struct of_overlay_info *ovinfo_tab) +{ + struct of_overlay_info *ovinfo; + int i; + + if (!ovinfo_tab || count < 0) + return -EINVAL; + + /* do it in reverse */ + for (i = count - 1; i >= 0; i--) { + ovinfo = &ovinfo_tab[i]; + + of_node_put(ovinfo->target); + of_node_put(ovinfo->overlay); + } + kfree(ovinfo_tab); + + return 0; +} + diff --git a/include/linux/of.h b/include/linux/of.h index ab52243..8a908f0 100644 --- a/include/linux/of.h +++ b/include/linux/of.h @@ -667,4 +667,111 @@ static inline int of_resolve(struct device_node *resolve) #endif +/** + * Overlay support + */ + +/** + * struct of_overlay_log_entry - Holds a DT log entry + * @node: list_head for the log list + * @action: notifier action + * @np: pointer to the device node affected + * @prop: pointer to the property affected + * @old_prop: hold a pointer to the original property + * + * Every modification of the device tree during application of the + * overlay is held in a list of of_overlay_log_entry structures. + * That way we can recover from a partial application, or we can + * revert the overlay properly. + */ +struct of_overlay_log_entry { + struct list_head node; + unsigned long action; + struct device_node *np; + struct property *prop; + struct property *old_prop; +}; + +/** + * struct of_overlay_device_entry - Holds an overlay device entry + * @node: list_head for the device list + * @np: device node pointer to the device node affected + * @pdev: pointer to the platform device affected + * @state: new device state + * + * When the overlay results in a device node's state to change this + * fact is recorded in a list of device entries. After the overlay + * is applied we can create/destroy the platform devices according + * to the new state of the live tree. + */ +struct of_overlay_device_entry { + struct list_head node; + struct device_node *np; + struct platform_device *pdev; + int state; +}; + +/** + * struct of_overlay_info - Holds a single overlay info + * @target: target of the overlay operation + * @overlay: pointer to the overlay contents node + * @lock: Lock to hold when accessing the lists + * @le_list: List of the overlay logs + * @de_list: List of the overlay records + * @notifier: of reconfiguration notifier + * + * Holds a single overlay state, including all the overlay logs & + * records. + */ +struct of_overlay_info { + struct device_node *target; + struct device_node *overlay; + struct mutex lock; + struct list_head le_list; + struct list_head de_list; + struct notifier_block notifier; +}; + +#ifdef CONFIG_OF_OVERLAY + +int of_overlay(int count, struct of_overlay_info *ovinfo_tab); +int of_overlay_revert(int count, struct of_overlay_info *ovinfo_tab); + +int of_fill_overlay_info(struct device_node *info_node, + struct of_overlay_info *ovinfo); +int of_build_overlay_info(struct device_node *tree, + int *cntp, struct of_overlay_info **ovinfop); +int of_free_overlay_info(int cnt, struct of_overlay_info *ovinfo); + +#else + +static inline int of_overlay(int count, struct of_overlay_info *ovinfo_tab) +{ + return -ENOTSUPP; +} + +static inline int of_overlay_revert(int count, struct of_overlay_info *ovinfo_tab) +{ + return -ENOTSUPP; +} + +static inline int of_fill_overlay_info(struct device_node *info_node, + struct of_overlay_info *ovinfo) +{ + return -ENOTSUPP; +} + +static inline int of_build_overlay_info(struct device_node *tree, + int *cntp, struct of_overlay_info **ovinfop) +{ + return -ENOTSUPP; +} + +int of_free_overlay_info(int cnt, struct of_overlay_info *ovinfo) +{ + return -ENOTSUPP; +} + +#endif + #endif /* _LINUX_OF_H */ -- 1.7.12 _______________________________________________ devicetree-discuss mailing list devicetree-discuss@lists.ozlabs.org https://lists.ozlabs.org/listinfo/devicetree-discuss