Patch from: https://lore.kernel.org/patchwork/patch/468129/ This patch will not compile with the 4.9.87 kernel. ConfigFS overlay ================================================================================== diff -aNru linux-4.9.87.orig/drivers/of/Kconfig linux-4.9.87/drivers/of/Kconfig --- linux-4.9.87.orig/drivers/of/Kconfig 2018-12-05 10:47:45.348494186 -0600 +++ linux-4.9.87/drivers/of/Kconfig 2018-12-05 11:05:10.272463251 -0600 @@ -112,4 +112,11 @@ config OF_NUMA bool +config OF_CONFIGFS + bool "OpenFirmware Overlay ConfigFS interface" + select CONFIGFS_FS + select OF_OVERLAY + help + Enable a simple user-space driver DT overlay interface. + endif # OF diff -aNru linux-4.9.87.orig/drivers/of/Makefile linux-4.9.87/drivers/of/Makefile --- linux-4.9.87.orig/drivers/of/Makefile 2018-12-05 10:48:27.836492928 -0600 +++ linux-4.9.87/drivers/of/Makefile 2018-12-05 11:05:57.668461848 -0600 @@ -14,5 +14,6 @@ obj-$(CONFIG_OF_RESOLVE) += resolver.o obj-$(CONFIG_OF_OVERLAY) += overlay.o obj-$(CONFIG_OF_NUMA) += of_numa.o +obj-$(CONFIG_OF_CONFIGFS) += configfs.o obj-$(CONFIG_OF_UNITTEST) += unittest-data/ diff -aNru linux-4.9.87.orig/drivers/of/configfs.c linux-4.9.87/drivers/of/configfs.c --- linux-4.9.87.orig/drivers/of/configfs.c 1969-12-31 18:00:00.000000000 -0600 +++ linux-4.9.87/drivers/of/configfs.c 2018-12-05 10:58:59.056474241 -0600 @@ -0,0 +1,251 @@ +/* + * Configfs entries for device-tree + * + * Copyright (C) 2013 - Pantelis Antoniou + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "of_private.h" + +#ifdef CONFIG_OF_OVERLAY + +struct cfs_overlay_item { + struct config_item item; + + char path[PATH_MAX]; + + const struct firmware *fw; + struct device_node *overlay; + int ov_id; +}; + +static inline struct cfs_overlay_item *to_cfs_overlay_item( + struct config_item *item) +{ + return item ? container_of(item, struct cfs_overlay_item, item) : NULL; +} + +CONFIGFS_ATTR_STRUCT(cfs_overlay_item); +#define CFS_OVERLAY_ITEM_ATTR(_name, _mode, _show, _store) \ +struct cfs_overlay_item_attribute cfs_overlay_item_attr_##_name = \ + __CONFIGFS_ATTR(_name, _mode, _show, _store) +#define CFS_OVERLAY_ITEM_ATTR_RO(_name, _show) \ +struct cfs_overlay_item_attribute cfs_overlay_item_attr_##_name = \ + __CONFIGFS_ATTR_RO(_name, _show) + +static ssize_t cfs_overlay_item_path_show(struct cfs_overlay_item *overlay, + char *page) +{ + return sprintf(page, "%s\n", overlay->path); +} + +static ssize_t cfs_overlay_item_path_store(struct cfs_overlay_item *overlay, + const char *page, size_t count) +{ + const char *p = page; + char *s; + int err; + + /* if it's set do not allow changes */ + if (overlay->path[0] != '\0') + return -EPERM; + + /* copy to path buffer (and make sure it's always zero terminated */ + count = snprintf(overlay->path, sizeof(overlay->path) - 1, "%s", p); + overlay->path[sizeof(overlay->path) - 1] = '\0'; + + /* strip trailing newlines */ + s = overlay->path + strlen(overlay->path); + while (s > overlay->path && *--s == '\n') + *s = '\0'; + + pr_debug("%s: path is '%s'\n", __func__, overlay->path); + + err = request_firmware(&overlay->fw, overlay->path, NULL); + if (err != 0) + goto out_err; + + /* unflatten the tree */ + of_fdt_unflatten_tree((void *)overlay->fw->data, &overlay->overlay); + if (overlay->overlay == NULL) { + pr_err("%s: failed to unflatten tree\n", __func__); + err = -EINVAL; + goto out_err; + } + pr_debug("%s: unflattened OK\n", __func__); + + /* mark it as detached */ + of_node_set_flag(overlay->overlay, OF_DETACHED); + + /* perform resolution */ + err = of_resolve(overlay->overlay); + if (err != 0) { + pr_err("%s: Failed to resolve tree\n", __func__); + goto out_err; + } + pr_debug("%s: resolved OK\n", __func__); + + err = of_overlay_create(overlay->overlay); + if (err < 0) { + pr_err("%s: Failed to create overlay (err=%d)\n", + __func__, err); + goto out_err; + } + overlay->ov_id = err; + + return count; + +out_err: + + release_firmware(overlay->fw); + overlay->fw = NULL; + + overlay->path[0] = '\0'; + return err; +} + +static ssize_t cfs_overlay_item_status_show(struct cfs_overlay_item *overlay, + char *page) +{ + return sprintf(page, "%s\n", + overlay->ov_id >= 0 ? "applied" : "unapplied"); +} + +CFS_OVERLAY_ITEM_ATTR(path, S_IRUGO | S_IWUSR, + cfs_overlay_item_path_show, cfs_overlay_item_path_store); +CFS_OVERLAY_ITEM_ATTR_RO(status, cfs_overlay_item_status_show); + +static struct configfs_attribute *cfs_overlay_attrs[] = { + &cfs_overlay_item_attr_path.attr, + &cfs_overlay_item_attr_status.attr, + NULL, +}; + +static void cfs_overlay_release(struct config_item *item) +{ + struct cfs_overlay_item *overlay = to_cfs_overlay_item(item); + + if (overlay->ov_id >= 0) + of_overlay_destroy(overlay->ov_id); + if (overlay->fw) + release_firmware(overlay->fw); + kfree(overlay); +} + +CONFIGFS_ATTR_OPS(cfs_overlay_item); +static struct configfs_item_operations cfs_overlay_item_ops = { + .release = cfs_overlay_release, + .show_attribute = cfs_overlay_item_attr_show, + .store_attribute = cfs_overlay_item_attr_store, +}; + +static struct config_item_type cfs_overlay_type = { + .ct_item_ops = &cfs_overlay_item_ops, + .ct_attrs = cfs_overlay_attrs, + .ct_owner = THIS_MODULE, +}; + +static struct config_item *cfs_overlay_group_make_item( + struct config_group *group, const char *name) +{ + struct cfs_overlay_item *overlay; + + overlay = kzalloc(sizeof(*overlay), GFP_KERNEL); + if (!overlay) + return ERR_PTR(-ENOMEM); + overlay->ov_id = -1; + + config_item_init_type_name(&overlay->item, name, &cfs_overlay_type); + return &overlay->item; +} + +static void cfs_overlay_group_drop_item(struct config_group *group, + struct config_item *item) +{ + struct cfs_overlay_item *overlay = to_cfs_overlay_item(item); + + config_item_put(&overlay->item); +} + +static struct configfs_group_operations overlays_ops = { + .make_item = cfs_overlay_group_make_item, + .drop_item = cfs_overlay_group_drop_item, +}; + +static struct config_item_type overlays_type = { + .ct_group_ops = &overlays_ops, + .ct_owner = THIS_MODULE, +}; + +#endif /* CONFIG_OF_OVERLAY */ + +static struct configfs_group_operations of_cfs_ops = { + /* empty - we don't allow anything to be created */ +}; + +static struct config_item_type of_cfs_type = { + .ct_group_ops = &of_cfs_ops, + .ct_owner = THIS_MODULE, +}; + +struct config_group of_cfs_overlay_group; + +struct config_group *of_cfs_def_groups[] = { +#ifdef CONFIG_OF_OVERLAY + &of_cfs_overlay_group, +#endif + NULL +}; + +static struct configfs_subsystem of_cfs_subsys = { + .su_group = { + .cg_item = { + .ci_namebuf = "device-tree", + .ci_type = &of_cfs_type, + }, + .default_groups = of_cfs_def_groups, + }, + .su_mutex = __MUTEX_INITIALIZER(of_cfs_subsys.su_mutex), +}; + +static int __init of_cfs_init(void) +{ + int ret; + + pr_info("%s\n", __func__); + + config_group_init(&of_cfs_subsys.su_group); +#ifdef CONFIG_OF_OVERLAY + config_group_init_type_name(&of_cfs_overlay_group, "overlays", + &overlays_type); +#endif + + ret = configfs_register_subsystem(&of_cfs_subsys); + if (ret != 0) { + pr_err("%s: failed to register subsys\n", __func__); + goto out; + } + pr_info("%s: OK\n", __func__); +out: + return ret; +} +late_initcall(of_cfs_init);