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From:   Lizhi Hou <lizhi.hou@xilinx.com>
To:     <linux-kernel@vger.kernel.org>
CC:     Lizhi Hou <lizhi.hou@xilinx.com>, <linux-fpga@vger.kernel.org>,
        <maxz@xilinx.com>, <sonal.santan@xilinx.com>, <yliu@xilinx.com>,
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        <robh@kernel.org>, <dwmw2@infradead.org>,
        Max Zhen <max.zhen@xilinx.com>
Subject: [PATCH V4 XRT Alveo Infrastructure 3/5] of: create empty of root
Date:   Wed, 5 Jan 2022 14:50:11 -0800
Message-ID: <20220105225013.1567871-4-lizhi.hou@xilinx.com>
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When OF_FLATTREE is selected and there is not a device tree, create an
empty device tree root node. of/unittest.c code is referenced.

Signed-off-by: Sonal Santan <sonal.santan@xilinx.com>
Signed-off-by: Max Zhen <max.zhen@xilinx.com>
Signed-off-by: Lizhi Hou <lizhi.hou@xilinx.com>
---
 drivers/of/Makefile        |  5 +++
 drivers/of/fdt.c           | 90 ++++++++++++++++++++++++++++++++++++++
 drivers/of/fdt_default.dts |  5 +++
 drivers/of/of_private.h    | 17 +++++++
 drivers/of/unittest.c      | 72 ++----------------------------
 5 files changed, 120 insertions(+), 69 deletions(-)
 create mode 100644 drivers/of/fdt_default.dts

diff --git a/drivers/of/Makefile b/drivers/of/Makefile
index c13b982084a3..a2989055c578 100644
--- a/drivers/of/Makefile
+++ b/drivers/of/Makefile
@@ -1,5 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 obj-y = base.o device.o platform.o property.o
+
 obj-$(CONFIG_OF_KOBJ) += kobj.o
 obj-$(CONFIG_OF_DYNAMIC) += dynamic.o
 obj-$(CONFIG_OF_FLATTREE) += fdt.o
@@ -20,4 +21,8 @@ obj-y	+= kexec.o
 endif
 endif
 
+ifndef CONFIG_OF_UNITTEST
+obj-$(CONFIG_OF_FLATTREE) += fdt_default.dtb.o
+endif
+
 obj-$(CONFIG_OF_UNITTEST) += unittest-data/
diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 4546572af24b..66ef9ac97829 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -466,6 +466,96 @@ void *of_fdt_unflatten_tree(const unsigned long *blob,
 }
 EXPORT_SYMBOL_GPL(of_fdt_unflatten_tree);
 
+static int __init of_fdt_root_init(void)
+{
+	struct device_node *dt = NULL, *np;
+	void *fdt = NULL, *fdt_aligned;
+	struct property *prop = NULL;
+	__be32 *val = NULL;
+	int size, rc = 0;
+
+#if !defined(CONFIG_OF_UNITTEST)
+	if (of_root)
+		return 0;
+#endif
+	size = __dtb_fdt_default_end - __dtb_fdt_default_begin;
+
+	fdt = kmalloc(size + FDT_ALIGN_SIZE, GFP_KERNEL);
+	if (!fdt)
+		return -ENOMEM;
+
+	fdt_aligned = PTR_ALIGN(fdt, FDT_ALIGN_SIZE);
+	memcpy(fdt_aligned, __dtb_fdt_default_begin, size);
+
+	if (!of_fdt_unflatten_tree((const unsigned long *)fdt_aligned,
+				   NULL, &dt)) {
+		pr_warn("%s: unflatten default tree failed\n", __func__);
+		kfree(fdt);
+		return -ENODATA;
+	}
+	if (!dt) {
+		pr_warn("%s: empty default tree\n", __func__);
+		kfree(fdt);
+		return -ENODATA;
+	}
+
+	/*
+	 * This lock normally encloses of_resolve_phandles()
+	 */
+	of_overlay_mutex_lock();
+
+	rc = of_resolve_phandles(dt);
+	if (rc) {
+		pr_err("%s: Failed to resolve phandles (rc=%i)\n", __func__, rc);
+		goto failed;
+	}
+
+	if (!of_root) {
+		prop = kcalloc(2, sizeof(*prop), GFP_KERNEL);
+		if (!prop) {
+			rc = -ENOMEM;
+			goto failed;
+		}
+		val = kzalloc(sizeof(*val), GFP_KERNEL);
+		if (!val) {
+			rc = -ENOMEM;
+			goto failed;
+		}
+		*val = cpu_to_be32(sizeof(void *) / sizeof(u32));
+
+		prop->name = "#address-cells";
+		prop->value = val;
+		prop->length = sizeof(u32);
+		of_add_property(dt, prop);
+		prop++;
+		prop->name = "#size-cells";
+		prop->value = val;
+		prop->length = sizeof(u32);
+		of_add_property(dt, prop);
+		of_root = dt;
+		for_each_of_allnodes(np)
+			__of_attach_node_sysfs(np);
+		of_aliases = of_find_node_by_path("/aliases");
+		of_chosen = of_find_node_by_path("/chosen");
+		of_overlay_mutex_unlock();
+pr_info("OF ROOT FLAG %lx\n", of_root->_flags);
+		return 0;
+	}
+
+	unittest_data_add(dt);
+
+	of_overlay_mutex_unlock();
+
+	return 0;
+
+failed:
+	of_overlay_mutex_unlock();
+	kfree(val);
+	kfree(prop);
+	return rc;
+}
+pure_initcall(of_fdt_root_init);
+
 /* Everything below here references initial_boot_params directly. */
 int __initdata dt_root_addr_cells;
 int __initdata dt_root_size_cells;
diff --git a/drivers/of/fdt_default.dts b/drivers/of/fdt_default.dts
new file mode 100644
index 000000000000..d1f12a76dfc6
--- /dev/null
+++ b/drivers/of/fdt_default.dts
@@ -0,0 +1,5 @@
+// SPDX-License-Identifier: GPL-2.0
+/dts-v1/;
+
+/ {
+};
diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
index 631489f7f8c0..1ef93bccfdba 100644
--- a/drivers/of/of_private.h
+++ b/drivers/of/of_private.h
@@ -41,6 +41,18 @@ extern struct mutex of_mutex;
 extern struct list_head aliases_lookup;
 extern struct kset *of_kset;
 
+#if defined(CONFIG_OF_UNITTEST)
+extern u8 __dtb_testcases_begin[];
+extern u8 __dtb_testcases_end[];
+#define __dtb_fdt_default_begin		__dtb_testcases_begin
+#define __dtb_fdt_default_end		__dtb_testcases_end
+void __init unittest_data_add(struct device_node *dt);
+#else
+extern u8 __dtb_fdt_default_begin[];
+extern u8 __dtb_fdt_default_end[];
+static inline void unittest_data_add(struct device_node *dt) {}
+#endif
+
 #if defined(CONFIG_OF_DYNAMIC)
 extern int of_property_notify(int action, struct device_node *np,
 			      struct property *prop, struct property *old_prop);
@@ -84,6 +96,11 @@ static inline void __of_detach_node_sysfs(struct device_node *np) {}
 
 #if defined(CONFIG_OF_RESOLVE)
 int of_resolve_phandles(struct device_node *tree);
+#else
+static inline int of_resolve_phandles(struct device_node *tree)
+{
+	return 0;
+}
 #endif
 
 void __of_phandle_cache_inv_entry(phandle handle);
diff --git a/drivers/of/unittest.c b/drivers/of/unittest.c
index 8c056972a6dd..745f455235cc 100644
--- a/drivers/of/unittest.c
+++ b/drivers/of/unittest.c
@@ -1402,73 +1402,15 @@ static void attach_node_and_children(struct device_node *np)
  *	unittest_data_add - Reads, copies data from
  *	linked tree and attaches it to the live tree
  */
-static int __init unittest_data_add(void)
+void __init unittest_data_add(struct device_node *dt)
 {
-	void *unittest_data;
-	void *unittest_data_align;
-	struct device_node *unittest_data_node = NULL, *np;
-	/*
-	 * __dtb_testcases_begin[] and __dtb_testcases_end[] are magically
-	 * created by cmd_dt_S_dtb in scripts/Makefile.lib
-	 */
-	extern uint8_t __dtb_testcases_begin[];
-	extern uint8_t __dtb_testcases_end[];
-	const int size = __dtb_testcases_end - __dtb_testcases_begin;
-	int rc;
-	void *ret;
-
-	if (!size) {
-		pr_warn("%s: testcases is empty\n", __func__);
-		return -ENODATA;
-	}
-
-	/* creating copy */
-	unittest_data = kmalloc(size + FDT_ALIGN_SIZE, GFP_KERNEL);
-	if (!unittest_data)
-		return -ENOMEM;
-
-	unittest_data_align = PTR_ALIGN(unittest_data, FDT_ALIGN_SIZE);
-	memcpy(unittest_data_align, __dtb_testcases_begin, size);
-
-	ret = of_fdt_unflatten_tree(unittest_data_align, NULL, &unittest_data_node);
-	if (!ret) {
-		pr_warn("%s: unflatten testcases tree failed\n", __func__);
-		kfree(unittest_data);
-		return -ENODATA;
-	}
-	if (!unittest_data_node) {
-		pr_warn("%s: testcases tree is empty\n", __func__);
-		kfree(unittest_data);
-		return -ENODATA;
-	}
-
-	/*
-	 * This lock normally encloses of_resolve_phandles()
-	 */
-	of_overlay_mutex_lock();
-
-	rc = of_resolve_phandles(unittest_data_node);
-	if (rc) {
-		pr_err("%s: Failed to resolve phandles (rc=%i)\n", __func__, rc);
-		of_overlay_mutex_unlock();
-		return -EINVAL;
-	}
-
-	if (!of_root) {
-		of_root = unittest_data_node;
-		for_each_of_allnodes(np)
-			__of_attach_node_sysfs(np);
-		of_aliases = of_find_node_by_path("/aliases");
-		of_chosen = of_find_node_by_path("/chosen");
-		of_overlay_mutex_unlock();
-		return 0;
-	}
+	struct device_node *np;
 
 	EXPECT_BEGIN(KERN_INFO,
 		     "Duplicate name in testcase-data, renamed to \"duplicate-name#1\"");
 
 	/* attach the sub-tree to live tree */
-	np = unittest_data_node->child;
+	np = dt->child;
 	while (np) {
 		struct device_node *next = np->sibling;
 
@@ -1479,10 +1421,6 @@ static int __init unittest_data_add(void)
 
 	EXPECT_END(KERN_INFO,
 		   "Duplicate name in testcase-data, renamed to \"duplicate-name#1\"");
-
-	of_overlay_mutex_unlock();
-
-	return 0;
 }
 
 #ifdef CONFIG_OF_OVERLAY
@@ -3258,7 +3196,6 @@ static inline __init void of_unittest_overlay_high_level(void) {}
 static int __init of_unittest(void)
 {
 	struct device_node *np;
-	int res;
 
 	pr_info("start of unittest - you will see error messages\n");
 
@@ -3267,9 +3204,6 @@ static int __init of_unittest(void)
 	if (IS_ENABLED(CONFIG_UML))
 		unittest_unflatten_overlay_base();
 
-	res = unittest_data_add();
-	if (res)
-		return res;
 	if (!of_aliases)
 		of_aliases = of_find_node_by_path("/aliases");
 
-- 
2.27.0