Add a runtime interface to using configfs for generic device tree overlay
usage.
A device-tree configfs entry is created in /config/device-tree/overlays
To create an overlay you mkdir the directory and then echo the overlay
firmware file to the path property file.
# mkdir /config/device-tree/overlays/foo
# echo foo.dtbo >/config/device-tree/overlays/foo/path
The overlay file will be loaded using the standard firmware loader
and will be applied.
To remove it simply rmdir the directory.
# rmdir /config/device-tree/overlays/foo
Signed-off-by: Pantelis Antoniou <pantelis.antoniou@xxxxxxxxxxxx>
---
drivers/of/Kconfig | 5 +
drivers/of/Makefile | 1 +
drivers/of/configfs.c | 272 ++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 278 insertions(+)
create mode 100644 drivers/of/configfs.c
diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig
index 7517be2..fc0e3ec 100644
--- a/drivers/of/Kconfig
+++ b/drivers/of/Kconfig
@@ -77,6 +77,10 @@ config OF_RESERVED_MEM
help
Helpers to allow for reservation of memory regions
+config OF_CONFIGFS
+ select CONFIGFS_FS
+ def_bool n
+
config OF_RESOLVE
bool "OF Dynamic resolution support"
depends on OF
@@ -92,6 +96,7 @@ config OF_OVERLAY
select OF_DYNAMIC
select OF_DEVICE
select OF_RESOLVE
+ select OF_CONFIGFS
help
OpenFirmware overlay support. Allows you to modify on runtime the
live tree using overlays.
diff --git a/drivers/of/Makefile b/drivers/of/Makefile
index d2a6e0d..4efa17b 100644
--- a/drivers/of/Makefile
+++ b/drivers/of/Makefile
@@ -12,3 +12,4 @@ obj-$(CONFIG_OF_MTD) += of_mtd.o
obj-$(CONFIG_OF_RESERVED_MEM) += of_reserved_mem.o
obj-$(CONFIG_OF_RESOLVE) += resolver.o
obj-$(CONFIG_OF_OVERLAY) += overlay.o
+obj-$(CONFIG_OF_CONFIGFS) += configfs.o
diff --git a/drivers/of/configfs.c b/drivers/of/configfs.c
new file mode 100644
index 0000000..a494643
--- /dev/null
+++ b/drivers/of/configfs.c
@@ -0,0 +1,272 @@
+/*
+ * Configfs entries for device-tree
+ *
+ * Copyright (C) 2013 - Pantelis Antoniou <panto@xxxxxxxxxxxxxxxxxxxxxxx>
+ *
+ * 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 <linux/ctype.h>
+#include <linux/cpu.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_fdt.h>
+#include <linux/spinlock.h>
+#include <linux/slab.h>
+#include <linux/proc_fs.h>
+#include <linux/configfs.h>
+#include <linux/types.h>
+#include <linux/stat.h>
+#include <linux/limits.h>
+#include <linux/file.h>
+#include <linux/vmalloc.h>
+#include <linux/firmware.h>
+
+#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 ovinfo_cnt;
+ struct of_overlay_info *ovinfo;
+ unsigned int applied : 1;
+};
+
+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__);
+
+ /* now build an overlay info array */
+ err = of_build_overlay_info(overlay->overlay,
+ &overlay->ovinfo_cnt, &overlay->ovinfo);
+ if (err != 0) {
+ pr_err("%s: Failed to build overlay info\n", __func__);
+ goto out_err;
+ }
+
+ pr_debug("%s: built %d overlay segments\n", __func__,
+ overlay->ovinfo_cnt);
+
+ err = of_overlay(overlay->ovinfo_cnt, overlay->ovinfo);
+ if (err != 0) {
+ pr_err("%s: Failed to apply overlay\n", __func__);
+ goto out_err;
+ }
+
+ overlay->applied = 1;
+
+ pr_debug("%s: Applied #%d overlay segments\n", __func__,
+ overlay->ovinfo_cnt);
+
+ return count;
+
+out_err:
+ if (overlay->applied)
+ of_overlay_revert(overlay->ovinfo_cnt, overlay->ovinfo);
+ overlay->applied = 0;
+
+ if (overlay->ovinfo)
+ of_free_overlay_info(overlay->ovinfo_cnt, overlay->ovinfo);
+ overlay->ovinfo = NULL;
+ overlay->ovinfo_cnt = 0;
+
+ 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->applied ? "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->applied)
+ of_overlay_revert(overlay->ovinfo_cnt, overlay->ovinfo);
+ if (overlay->ovinfo)
+ of_free_overlay_info(overlay->ovinfo_cnt, overlay->ovinfo);
+ 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);
+
+ 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);
--
1.7.12
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