[RFC PATCH 1/5] of: introduce the overlay manager

From: Antoine Tenart
Date: Wed Oct 26 2016 - 10:58:24 EST

The overlay manager is an in-kernel library helping to handle dt overlay
loading when using capes.

Signed-off-by: Antoine Tenart <antoine.tenart@xxxxxxxxxxxxxxxxxx>
---
drivers/of/Kconfig | 2 +
drivers/of/Makefile | 1 +
drivers/of/overlay-manager/Kconfig | 6 +
drivers/of/overlay-manager/Makefile | 1 +
drivers/of/overlay-manager/overlay-manager.c | 199 +++++++++++++++++++++++++++
include/linux/overlay-manager.h | 38 +++++
6 files changed, 247 insertions(+)
create mode 100644 drivers/of/overlay-manager/Kconfig
create mode 100644 drivers/of/overlay-manager/Makefile
create mode 100644 drivers/of/overlay-manager/overlay-manager.c
create mode 100644 include/linux/overlay-manager.h

diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig
index bc07ad30c9bf..e57aeaf0bf4f 100644
--- a/drivers/of/Kconfig
+++ b/drivers/of/Kconfig
@@ -116,4 +116,6 @@ config OF_OVERLAY
config OF_NUMA
bool

+source "drivers/of/overlay-manager/Kconfig"
+
endif # OF
diff --git a/drivers/of/Makefile b/drivers/of/Makefile
index d7efd9d458aa..d738fd41271f 100644
--- a/drivers/of/Makefile
+++ b/drivers/of/Makefile
@@ -16,3 +16,4 @@ obj-$(CONFIG_OF_OVERLAY) += overlay.o
obj-$(CONFIG_OF_NUMA) += of_numa.o

obj-$(CONFIG_OF_UNITTEST) += unittest-data/
+obj-y += overlay-manager/
diff --git a/drivers/of/overlay-manager/Kconfig b/drivers/of/overlay-manager/Kconfig
new file mode 100644
index 000000000000..eeb76054dcb8
--- /dev/null
+++ b/drivers/of/overlay-manager/Kconfig
@@ -0,0 +1,6 @@
+config OF_OVERLAY_MGR
+ bool "Device Tree Overlay Manager"
+ depends on OF_OVERLAY
+ help
+ Enable the overlay manager to handle automatic overlay loading when
+ devices are detected.
diff --git a/drivers/of/overlay-manager/Makefile b/drivers/of/overlay-manager/Makefile
new file mode 100644
index 000000000000..86d2b53950e7
--- /dev/null
+++ b/drivers/of/overlay-manager/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_OF_OVERLAY_MGR) += overlay-manager.o
diff --git a/drivers/of/overlay-manager/overlay-manager.c b/drivers/of/overlay-manager/overlay-manager.c
new file mode 100644
index 000000000000..a725d7e24d38
--- /dev/null
+++ b/drivers/of/overlay-manager/overlay-manager.c
@@ -0,0 +1,199 @@
+/*
+ * Copyright (C) 2016 - Antoine Tenart <antoine.tenart@xxxxxxxxxxxxxxxxxx>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/firmware.h>
+#include <linux/list.h>
+#include <linux/of.h>
+#include <linux/of_fdt.h>
+#include <linux/overlay-manager.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+
+struct overlay_mgr_overlay {
+ struct list_head list;
+ char *name;
+};
+
+LIST_HEAD(overlay_mgr_overlays);
+LIST_HEAD(overlay_mgr_formats);
+DEFINE_SPINLOCK(overlay_mgr_lock);
+DEFINE_SPINLOCK(overlay_mgr_format_lock);
+
+/*
+ * overlay_mgr_register_format()
+ *
+ * Adds a new format candidate to the list of supported formats. The registered
+ * formats are used to parse the headers stored on the dips.
+ */
+int overlay_mgr_register_format(struct overlay_mgr_format *candidate)
+{
+ struct overlay_mgr_format *format;
+ int err = 0;
+
+ spin_lock(&overlay_mgr_format_lock);
+
+ /* Check if the format is already registered */
+ list_for_each_entry(format, &overlay_mgr_formats, list) {
+ if (!strcpy(format->name, candidate->name)) {
+ err = -EEXIST;
+ goto err;
+ }
+ }
+
+ list_add_tail(&candidate->list, &overlay_mgr_formats);
+
+err:
+ spin_unlock(&overlay_mgr_format_lock);
+ return err;
+}
+EXPORT_SYMBOL_GPL(overlay_mgr_register_format);
+
+/*
+ * overlay_mgr_parse()
+ *
+ * Parse raw data with registered format parsers. Fills the candidate string if
+ * one parser understood the raw data format.
+ */
+int overlay_mgr_parse(struct device *dev, void *data, char ***candidates,
+ unsigned *n)
+{
+ struct list_head *pos, *tmp;
+ struct overlay_mgr_format *format;
+
+ list_for_each_safe(pos, tmp, &overlay_mgr_formats) {
+ format = list_entry(pos, struct overlay_mgr_format, list);
+
+ format->parse(dev, data, candidates, n);
+ if (n > 0)
+ return 0;
+ }
+
+ return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(overlay_mgr_parse);
+
+static int overlay_mgr_check_overlay(struct device_node *node)
+{
+ struct property *p;
+ const char *str = NULL;
+
+ p = of_find_property(node, "compatible", NULL);
+ if (!p)
+ return -EINVAL;
+
+ do {
+ str = of_prop_next_string(p, str);
+ if (of_machine_is_compatible(str))
+ return 0;
+ } while (str);
+
+ return -EINVAL;
+}
+
+/*
+ * _overlay_mgr_insert()
+ *
+ * Try to request and apply an overlay given a candidate name.
+ */
+static int _overlay_mgr_apply(struct device *dev, char *candidate)
+{
+ struct overlay_mgr_overlay *overlay;
+ struct device_node *node;
+ const struct firmware *firmware;
+ char *firmware_name;
+ int err = 0;
+
+ spin_lock(&overlay_mgr_lock);
+
+ list_for_each_entry(overlay, &overlay_mgr_overlays, list) {
+ if (!strcmp(overlay->name, candidate)) {
+ dev_err(dev, "overlay already loaded\n");
+ err = -EEXIST;
+ goto err_lock;
+ }
+ }
+
+ overlay = devm_kzalloc(dev, sizeof(*overlay), GFP_KERNEL);
+ if (!overlay) {
+ err = -ENOMEM;
+ goto err_lock;
+ }
+
+ overlay->name = candidate;
+
+ firmware_name = kasprintf(GFP_KERNEL, "overlay-%s.dtbo", candidate);
+ if (!firmware_name) {
+ err = -ENOMEM;
+ goto err_free;
+ }
+
+ dev_info(dev, "requesting firmware '%s'\n", firmware_name);
+
+ err = request_firmware_direct(&firmware, firmware_name, dev);
+ if (err) {
+ dev_info(dev, "failed to request firmware '%s'\n",
+ firmware_name);
+ goto err_free;
+ }
+
+ of_fdt_unflatten_tree((unsigned long *)firmware->data, NULL, &node);
+ if (!node) {
+ dev_err(dev, "failed to unflatted tree\n");
+ err = -EINVAL;
+ goto err_fw;
+ }
+
+ of_node_set_flag(node, OF_DETACHED);
+
+ err = of_resolve_phandles(node);
+ if (err) {
+ dev_err(dev, "failed to resolve phandles: %d\n", err);
+ goto err_fw;
+ }
+
+ err = overlay_mgr_check_overlay(node);
+ if (err) {
+ dev_err(dev, "overlay checks failed: %d\n", err);
+ goto err_fw;
+ }
+
+ err = of_overlay_create(node);
+ if (err < 0) {
+ dev_err(dev, "failed to create overlay: %d\n", err);
+ goto err_fw;
+ }
+
+ list_add_tail(&overlay->list, &overlay_mgr_overlays);
+
+ dev_info(dev, "loaded firmware '%s'\n", firmware_name);
+
+ spin_unlock(&overlay_mgr_lock);
+ return 0;
+
+err_fw:
+ release_firmware(firmware);
+err_free:
+ devm_kfree(dev, overlay);
+err_lock:
+ spin_unlock(&overlay_mgr_lock);
+ return err;
+}
+
+int overlay_mgr_apply(struct device *dev, char **candidates, unsigned n)
+{
+ int i, ret;
+
+ for (i=0; i < n; i++) {
+ ret = _overlay_mgr_apply(dev, candidates[i]);
+ if (!ret)
+ return 0;
+ }
+
+ return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(overlay_mgr_apply);
diff --git a/include/linux/overlay-manager.h b/include/linux/overlay-manager.h
new file mode 100644
index 000000000000..8adcc4f5ddf6
--- /dev/null
+++ b/include/linux/overlay-manager.h
@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2016 - Antoine Tenart <antoine.tenart@xxxxxxxxxxxxxxxxxx>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#ifndef __OVERLAY_MGR_H__
+#define __OVERLAY_MGR_H__
+
+#include <linux/device.h>
+#include <linux/list.h>
+#include <linux/sizes.h>
+
+#define OVERLAY_MGR_DIP_MAX_SZ SZ_128
+
+struct overlay_mgr_format {
+ struct list_head list;
+ char *name;
+ int (*parse)(struct device *dev, void *data, char ***candidates,
+ unsigned *n);
+};
+
+int overlay_mgr_register_format(struct overlay_mgr_format *candidate);
+int overlay_mgr_parse(struct device *dev, void *data, char ***candidates,
+ unsigned *n);
+int overlay_mgr_apply(struct device *dev, char **candidates, unsigned n);
+
+#define dip_convert(field) \
+ ( \
+ (sizeof(field) == 1) ? field : \
+ (sizeof(field) == 2) ? be16_to_cpu(field) : \
+ (sizeof(field) == 4) ? be32_to_cpu(field) : \
+ -1 \
+ )
+
+#endif /* __OVERLAY_MGR_H__ */
--
2.10.1