[PATCH v4 0/7] of: populate of_root node if bootloader doesn't

[PATCH v4 0/7] of: populate of_root node if bootloader doesn't

[Stephen Boyd]

Arch maintainers, please ack/review patches.

This is a resend of a series from Frank last year[1]. I worked in Rob's
review comments to unconditionally call unflatten_device_tree() and
fixup/audit calls to of_have_populated_dt() so that behavior doesn't
change.

I need this series so I can add DT based tests in the clk framework.
Either I can merge it through the clk tree once everyone is happy, or
Rob can merge it through the DT tree and provide some branch so I can
base clk patches on it.

Changes from v3 (https://lore.kernel.org/r/20240202195909.3458162-1-sboyd@kernel.org):
 * Made OF_UNITTEST depend on OF_EARLY_FLATREE
 * Made OF_EARLY_FLATREE depend on absence of arches that don't call
   unflatten_device_tree()
 * Added of_ prefix to dtb_ prefixed KUnit tests
 * Picked up tags

Changes from v2 (https://lore.kernel.org/r/20240130004508.1700335-1-sboyd@kernel.org):
 * Reorder patches to have OF changes largely first
 * No longer modify initial_boot_params if ACPI=y
 * Put arm64 patch back to v1

Changes from v1 (https://lore.kernel.org/r/20240112200750.4062441-1-sboyd@kernel.org):
 * x86 patch included
 * arm64 knocks out initial dtb if acpi is in use
 * keep Kconfig hidden but def_bool enabled otherwise

Changes from Frank's series[1]:
 * Add a DTB loaded kunit test
 * Make of_have_populated_dt() return false if the DTB isn't from the
   bootloader
 * Architecture calls made unconditional so that a root node is always
   made

Frank Rowand (2):
  of: Create of_root if no dtb provided by firmware
  of: unittest: treat missing of_root as error instead of fixing up

Stephen Boyd (5):
  of: Always unflatten in unflatten_and_copy_device_tree()
  um: Unconditionally call unflatten_device_tree()
  x86/of: Unconditionally call unflatten_and_copy_device_tree()
  arm64: Unconditionally call unflatten_device_tree()
  of: Add KUnit test to confirm DTB is loaded

 arch/arm64/kernel/setup.c    |  3 +-
 arch/um/kernel/dtb.c         | 14 ++++----
 arch/x86/kernel/devicetree.c | 24 +++++++-------
 drivers/of/.kunitconfig      |  3 ++
 drivers/of/Kconfig           | 14 ++++++--
 drivers/of/Makefile          |  4 ++-
 drivers/of/empty_root.dts    |  6 ++++
 drivers/of/fdt.c             | 64 +++++++++++++++++++++++++++---------
 drivers/of/of_test.c         | 57 ++++++++++++++++++++++++++++++++
 drivers/of/platform.c        |  3 --
 drivers/of/unittest.c        | 16 +++------
 include/linux/of.h           | 25 ++++++++------
 12 files changed, 168 insertions(+), 65 deletions(-)
 create mode 100644 drivers/of/.kunitconfig
 create mode 100644 drivers/of/empty_root.dts
 create mode 100644 drivers/of/of_test.c

[1] https://lore.kernel.org/r/20230317053415.2254616-1-frowand.list@gmail.com

base-commit: 6613476e225e090cc9aad49be7fa504e290dd33d
-- 
https://git.kernel.org/pub/scm/linux/kernel/git/clk/linux.git/
https://git.kernel.org/pub/scm/linux/kernel/git/sboyd/spmi.git

[PATCH v4 1/7] of: Always unflatten in unflatten_and_copy_device_tree()

[Stephen Boyd]

We want to populate an empty DT whenever CONFIG_OF is enabled so that
overlays can be applied and the DT unit tests can be run. Make
unflatten_and_copy_device_tree() stop printing a warning if the
'initial_boot_params' pointer is NULL. Instead, simply copy the dtb if
there is one and then unflatten it. If there isn't a DT to copy, then
the call to unflatten_device_tree() is largely a no-op, so nothing
really changes here.

Cc: Rob Herring <robh+dt@kernel.org>
Cc: Frank Rowand <frowand.list@gmail.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
---
 drivers/of/fdt.c | 32 +++++++++++++++++---------------
 1 file changed, 17 insertions(+), 15 deletions(-)

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index bf502ba8da95..dfeba8b8ce94 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -1318,6 +1318,21 @@ bool __init early_init_dt_scan(void *params)
 	return true;
 }
 
+static void *__init copy_device_tree(void *fdt)
+{
+	int size;
+	void *dt;
+
+	size = fdt_totalsize(fdt);
+	dt = early_init_dt_alloc_memory_arch(size,
+					     roundup_pow_of_two(FDT_V17_SIZE));
+
+	if (dt)
+		memcpy(dt, fdt, size);
+
+	return dt;
+}
+
 /**
  * unflatten_device_tree - create tree of device_nodes from flat blob
  *
@@ -1350,22 +1365,9 @@ void __init unflatten_device_tree(void)
  */
 void __init unflatten_and_copy_device_tree(void)
 {
-	int size;
-	void *dt;
+	if (initial_boot_params)
+		initial_boot_params = copy_device_tree(initial_boot_params);
 
-	if (!initial_boot_params) {
-		pr_warn("No valid device tree found, continuing without\n");
-		return;
-	}
-
-	size = fdt_totalsize(initial_boot_params);
-	dt = early_init_dt_alloc_memory_arch(size,
-					     roundup_pow_of_two(FDT_V17_SIZE));
-
-	if (dt) {
-		memcpy(dt, initial_boot_params, size);
-		initial_boot_params = dt;
-	}
 	unflatten_device_tree();
 }
 
-- 
https://git.kernel.org/pub/scm/linux/kernel/git/clk/linux.git/
https://git.kernel.org/pub/scm/linux/kernel/git/sboyd/spmi.git

[PATCH v4 2/7] of: Create of_root if no dtb provided by firmware

[Stephen Boyd]

From: Frank Rowand <frowand.list@gmail.com>

When enabling CONFIG_OF on a platform where 'of_root' is not populated
by firmware, we end up without a root node. In order to apply overlays
and create subnodes of the root node, we need one. Create this root node
by unflattening an empty builtin dtb.

If firmware provides a flattened device tree (FDT) then the FDT is
unflattened via setup_arch(). Otherwise, the call to
unflatten(_and_copy)?_device_tree() will create an empty root node.

We make of_have_populated_dt() return true only if the DTB was loaded by
firmware so that existing callers don't change behavior after this
patch. The call in the of platform code is removed because it prevents
overlays from creating platform devices when the empty root node is
used.

Signed-off-by: Frank Rowand <frowand.list@gmail.com>
Link: https://lore.kernel.org/r/20230317053415.2254616-2-frowand.list@gmail.com
Cc: Rob Herring <robh+dt@kernel.org>
[sboyd@kernel.org: Update of_have_populated_dt() to treat this empty dtb
as not populated. Drop setup_of() initcall]
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
---
 drivers/of/Kconfig        |  5 ++---
 drivers/of/Makefile       |  2 +-
 drivers/of/empty_root.dts |  6 ++++++
 drivers/of/fdt.c          | 32 +++++++++++++++++++++++++++++++-
 drivers/of/platform.c     |  3 ---
 include/linux/of.h        | 25 +++++++++++++++----------
 6 files changed, 55 insertions(+), 18 deletions(-)
 create mode 100644 drivers/of/empty_root.dts

diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig
index da9826accb1b..d738fbad9c36 100644
--- a/drivers/of/Kconfig
+++ b/drivers/of/Kconfig
@@ -14,9 +14,8 @@ if OF
 
 config OF_UNITTEST
 	bool "Device Tree runtime unit tests"
-	depends on !SPARC
+	depends on OF_EARLY_FLATTREE
 	select IRQ_DOMAIN
-	select OF_EARLY_FLATTREE
 	select OF_RESOLVE
 	help
 	  This option builds in test cases for the device tree infrastructure
@@ -54,7 +53,7 @@ config OF_FLATTREE
 	select CRC32
 
 config OF_EARLY_FLATTREE
-	bool
+	def_bool OF && !(SPARC || ALPHA || HEXAGON || M68K || PARISC || S390)
 	select DMA_DECLARE_COHERENT if HAS_DMA && HAS_IOMEM
 	select OF_FLATTREE
 
diff --git a/drivers/of/Makefile b/drivers/of/Makefile
index eff624854575..df305348d1cb 100644
--- a/drivers/of/Makefile
+++ b/drivers/of/Makefile
@@ -2,7 +2,7 @@
 obj-y = base.o cpu.o device.o module.o platform.o property.o
 obj-$(CONFIG_OF_KOBJ) += kobj.o
 obj-$(CONFIG_OF_DYNAMIC) += dynamic.o
-obj-$(CONFIG_OF_FLATTREE) += fdt.o
+obj-$(CONFIG_OF_FLATTREE) += fdt.o empty_root.dtb.o
 obj-$(CONFIG_OF_EARLY_FLATTREE) += fdt_address.o
 obj-$(CONFIG_OF_PROMTREE) += pdt.o
 obj-$(CONFIG_OF_ADDRESS)  += address.o
diff --git a/drivers/of/empty_root.dts b/drivers/of/empty_root.dts
new file mode 100644
index 000000000000..cf9e97a60f48
--- /dev/null
+++ b/drivers/of/empty_root.dts
@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/dts-v1/;
+
+/ {
+
+};
diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index dfeba8b8ce94..e5a385285149 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -8,6 +8,7 @@
 
 #define pr_fmt(fmt)	"OF: fdt: " fmt
 
+#include <linux/acpi.h>
 #include <linux/crash_dump.h>
 #include <linux/crc32.h>
 #include <linux/kernel.h>
@@ -32,6 +33,13 @@
 
 #include "of_private.h"
 
+/*
+ * __dtb_empty_root_begin[] and __dtb_empty_root_end[] magically created by
+ * cmd_dt_S_dtb in scripts/Makefile.lib
+ */
+extern uint8_t __dtb_empty_root_begin[];
+extern uint8_t __dtb_empty_root_end[];
+
 /*
  * of_fdt_limit_memory - limit the number of regions in the /memory node
  * @limit: maximum entries
@@ -1343,7 +1351,29 @@ static void *__init copy_device_tree(void *fdt)
  */
 void __init unflatten_device_tree(void)
 {
-	__unflatten_device_tree(initial_boot_params, NULL, &of_root,
+	void *fdt = initial_boot_params;
+
+	/* Don't use the bootloader provided DTB if ACPI is enabled */
+	if (!acpi_disabled)
+		fdt = NULL;
+
+	/*
+	 * Populate an empty root node when ACPI is enabled or bootloader
+	 * doesn't provide one.
+	 */
+	if (!fdt) {
+		fdt = (void *) __dtb_empty_root_begin;
+		/* fdt_totalsize() will be used for copy size */
+		if (fdt_totalsize(fdt) >
+		    __dtb_empty_root_end - __dtb_empty_root_begin) {
+			pr_err("invalid size in dtb_empty_root\n");
+			return;
+		}
+		of_fdt_crc32 = crc32_be(~0, fdt, fdt_totalsize(fdt));
+		fdt = copy_device_tree(fdt);
+	}
+
+	__unflatten_device_tree(fdt, NULL, &of_root,
 				early_init_dt_alloc_memory_arch, false);
 
 	/* Get pointer to "/chosen" and "/aliases" nodes for use everywhere */
diff --git a/drivers/of/platform.c b/drivers/of/platform.c
index b7708a06dc78..39c0ceee3e95 100644
--- a/drivers/of/platform.c
+++ b/drivers/of/platform.c
@@ -510,9 +510,6 @@ static int __init of_platform_default_populate_init(void)
 
 	device_links_supplier_sync_state_pause();
 
-	if (!of_have_populated_dt())
-		return -ENODEV;
-
 	if (IS_ENABLED(CONFIG_PPC)) {
 		struct device_node *boot_display = NULL;
 		struct platform_device *dev;
diff --git a/include/linux/of.h b/include/linux/of.h
index 6a9ddf20e79a..52f6ad6a1c8c 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -180,11 +180,6 @@ static inline bool is_of_node(const struct fwnode_handle *fwnode)
 			&__of_fwnode_handle_node->fwnode : NULL;	\
 	})
 
-static inline bool of_have_populated_dt(void)
-{
-	return of_root != NULL;
-}
-
 static inline bool of_node_is_root(const struct device_node *node)
 {
 	return node && (node->parent == NULL);
@@ -549,11 +544,6 @@ static inline struct device_node *of_find_node_with_property(
 
 #define of_fwnode_handle(node) NULL
 
-static inline bool of_have_populated_dt(void)
-{
-	return false;
-}
-
 static inline struct device_node *of_get_compatible_child(const struct device_node *parent,
 					const char *compatible)
 {
@@ -1634,6 +1624,21 @@ static inline bool of_device_is_system_power_controller(const struct device_node
 	return of_property_read_bool(np, "system-power-controller");
 }
 
+/**
+ * of_have_populated_dt() - Has DT been populated by bootloader
+ *
+ * Return: True if a DTB has been populated by the bootloader and it isn't the
+ * empty builtin one. False otherwise.
+ */
+static inline bool of_have_populated_dt(void)
+{
+#ifdef CONFIG_OF
+	return of_property_present(of_root, "compatible");
+#else
+	return false;
+#endif
+}
+
 /*
  * Overlay support
  */
-- 
https://git.kernel.org/pub/scm/linux/kernel/git/clk/linux.git/
https://git.kernel.org/pub/scm/linux/kernel/git/sboyd/spmi.git

[PATCH v4 3/7] um: Unconditionally call unflatten_device_tree()

[Stephen Boyd]

Call this function unconditionally so that we can populate an empty DTB
on platforms that don't boot with a command line provided DTB.  There's
no harm in calling unflatten_device_tree() unconditionally. If there
isn't a valid initial_boot_params dtb then unflatten_device_tree()
returns early.

Cc: Rob Herring <robh+dt@kernel.org>
Cc: Frank Rowand <frowand.list@gmail.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: <linux-um@lists.infradead.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
---
 arch/um/kernel/dtb.c  | 14 +++++++-------
 drivers/of/unittest.c |  4 ----
 2 files changed, 7 insertions(+), 11 deletions(-)

diff --git a/arch/um/kernel/dtb.c b/arch/um/kernel/dtb.c
index 484141b06938..4954188a6a09 100644
--- a/arch/um/kernel/dtb.c
+++ b/arch/um/kernel/dtb.c
@@ -16,16 +16,16 @@ void uml_dtb_init(void)
 	void *area;
 
 	area = uml_load_file(dtb, &size);
-	if (!area)
-		return;
+	if (area) {
+		if (!early_init_dt_scan(area)) {
+			pr_err("invalid DTB %s\n", dtb);
+			memblock_free(area, size);
+			return;
+		}
 
-	if (!early_init_dt_scan(area)) {
-		pr_err("invalid DTB %s\n", dtb);
-		memblock_free(area, size);
-		return;
+		early_init_fdt_scan_reserved_mem();
 	}
 
-	early_init_fdt_scan_reserved_mem();
 	unflatten_device_tree();
 }
 
diff --git a/drivers/of/unittest.c b/drivers/of/unittest.c
index cfd60e35a899..891752a20a5f 100644
--- a/drivers/of/unittest.c
+++ b/drivers/of/unittest.c
@@ -4087,10 +4087,6 @@ static int __init of_unittest(void)
 	add_taint(TAINT_TEST, LOCKDEP_STILL_OK);
 
 	/* adding data for unittest */
-
-	if (IS_ENABLED(CONFIG_UML))
-		unittest_unflatten_overlay_base();
-
 	res = unittest_data_add();
 	if (res)
 		return res;
-- 
https://git.kernel.org/pub/scm/linux/kernel/git/clk/linux.git/
https://git.kernel.org/pub/scm/linux/kernel/git/sboyd/spmi.git

[PATCH v4 4/7] x86/of: Unconditionally call unflatten_and_copy_device_tree()

[Stephen Boyd]

Call this function unconditionally so that we can populate an empty DTB
on platforms that don't boot with a firmware provided or builtin DTB.
There's no harm in calling unflatten_device_tree() unconditionally here.
If there isn't a non-NULL 'initial_boot_params' pointer then
unflatten_device_tree() returns early.

Cc: Rob Herring <robh+dt@kernel.org>
Cc: Frank Rowand <frowand.list@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: <x86@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Tested-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
---
 arch/x86/kernel/devicetree.c | 24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kernel/devicetree.c b/arch/x86/kernel/devicetree.c
index afd09924094e..650752d112a6 100644
--- a/arch/x86/kernel/devicetree.c
+++ b/arch/x86/kernel/devicetree.c
@@ -283,22 +283,24 @@ void __init x86_flattree_get_config(void)
 	u32 size, map_len;
 	void *dt;
 
-	if (!initial_dtb)
-		return;
+	if (initial_dtb) {
+		map_len = max(PAGE_SIZE - (initial_dtb & ~PAGE_MASK), (u64)128);
 
-	map_len = max(PAGE_SIZE - (initial_dtb & ~PAGE_MASK), (u64)128);
+		dt = early_memremap(initial_dtb, map_len);
+		size = fdt_totalsize(dt);
+		if (map_len < size) {
+			early_memunmap(dt, map_len);
+			dt = early_memremap(initial_dtb, size);
+			map_len = size;
+		}
 
-	dt = early_memremap(initial_dtb, map_len);
-	size = fdt_totalsize(dt);
-	if (map_len < size) {
-		early_memunmap(dt, map_len);
-		dt = early_memremap(initial_dtb, size);
-		map_len = size;
+		early_init_dt_verify(dt);
 	}
 
-	early_init_dt_verify(dt);
 	unflatten_and_copy_device_tree();
-	early_memunmap(dt, map_len);
+
+	if (initial_dtb)
+		early_memunmap(dt, map_len);
 }
 #endif
 
-- 
https://git.kernel.org/pub/scm/linux/kernel/git/clk/linux.git/
https://git.kernel.org/pub/scm/linux/kernel/git/sboyd/spmi.git

[PATCH v4 5/7] arm64: Unconditionally call unflatten_device_tree()

[Stephen Boyd]

Call this function unconditionally so that we can populate an empty DTB
on platforms that don't boot with a firmware provided or builtin DTB.
When ACPI is in use, unflatten_device_tree() ignores the
'initial_boot_params' pointer so the live DT on those systems won't be
whatever that's pointing to. Similarly, when kexec copies the DT data
the previous kernel to the new one on ACPI systems,
of_kexec_alloc_and_setup_fdt() will ignore the live DT (the empty root
one) and copy the 'initial_boot_params' data.

Cc: Rob Herring <robh+dt@kernel.org>
Cc: Frank Rowand <frowand.list@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: <linux-arm-kernel@lists.infradead.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
---
 arch/arm64/kernel/setup.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 42c690bb2d60..0d210720d47d 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -351,8 +351,7 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p)
 	/* Parse the ACPI tables for possible boot-time configuration */
 	acpi_boot_table_init();
 
-	if (acpi_disabled)
-		unflatten_device_tree();
+	unflatten_device_tree();
 
 	bootmem_init();
 
-- 
https://git.kernel.org/pub/scm/linux/kernel/git/clk/linux.git/
https://git.kernel.org/pub/scm/linux/kernel/git/sboyd/spmi.git

[PATCH v4 6/7] of: unittest: treat missing of_root as error instead of fixing up

[Stephen Boyd]

From: Frank Rowand <frowand.list@gmail.com>

unflatten_device_tree() now ensures that the 'of_root' node is populated
with the root of a default empty devicetree. Remove the unittest code
that created 'of_root' if it was missing. Verify that 'of_root' is valid
before attempting to attach the testcase-data subtree. Remove the
unittest code that unflattens the unittest overlay base if architecture
is UML because that is always done now.

Signed-off-by: Frank Rowand <frowand.list@gmail.com>
Link: https://lore.kernel.org/r/20230317053415.2254616-3-frowand.list@gmail.com
Cc: Rob Herring <robh+dt@kernel.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
---
 drivers/of/unittest.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/drivers/of/unittest.c b/drivers/of/unittest.c
index 891752a20a5f..4c67de37bf26 100644
--- a/drivers/of/unittest.c
+++ b/drivers/of/unittest.c
@@ -1744,20 +1744,16 @@ static int __init unittest_data_add(void)
 		return -EINVAL;
 	}
 
+	/* attach the sub-tree to live tree */
 	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;
+		pr_warn("%s: no live tree to attach sub-tree\n", __func__);
+		kfree(unittest_data);
+		return -ENODEV;
 	}
 
 	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;
 	while (np) {
 		struct device_node *next = np->sibling;
-- 
https://git.kernel.org/pub/scm/linux/kernel/git/clk/linux.git/
https://git.kernel.org/pub/scm/linux/kernel/git/sboyd/spmi.git

[PATCH v4 7/7] of: Add KUnit test to confirm DTB is loaded

[Stephen Boyd]

Add a KUnit test that confirms a DTB has been loaded, i.e. there is a
root node, and that the of_have_populated_dt() API works properly. We
skip the test when CONFIG_OF_EARLY_FLATREE=n because in that case we
know architecture code hasn't called unflatten_(and_copy_)?device_tree()
which would populate some sort of root node.

Cc: Rob Herring <robh+dt@kernel.org>
Cc: Frank Rowand <frowand.list@gmail.com>
Reviewed-by: David Gow <davidgow@google.com>
Cc: Brendan Higgins <brendan.higgins@linux.dev>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
---
 drivers/of/.kunitconfig |  3 +++
 drivers/of/Kconfig      |  9 +++++++
 drivers/of/Makefile     |  2 ++
 drivers/of/of_test.c    | 57 +++++++++++++++++++++++++++++++++++++++++
 4 files changed, 71 insertions(+)
 create mode 100644 drivers/of/.kunitconfig
 create mode 100644 drivers/of/of_test.c

diff --git a/drivers/of/.kunitconfig b/drivers/of/.kunitconfig
new file mode 100644
index 000000000000..5a8fee11978c
--- /dev/null
+++ b/drivers/of/.kunitconfig
@@ -0,0 +1,3 @@
+CONFIG_KUNIT=y
+CONFIG_OF=y
+CONFIG_OF_KUNIT_TEST=y
diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig
index d738fbad9c36..dd726c7056bf 100644
--- a/drivers/of/Kconfig
+++ b/drivers/of/Kconfig
@@ -36,6 +36,15 @@ config OF_UNITTEST
 
 	  If unsure, say N here. This option is not safe to enable.
 
+config OF_KUNIT_TEST
+	tristate "Devicetree KUnit Test" if !KUNIT_ALL_TESTS
+	depends on KUNIT
+	default KUNIT_ALL_TESTS
+	help
+	  This option builds KUnit unit tests for device tree infrastructure.
+
+	  If unsure, say N here, but this option is safe to enable.
+
 config OF_ALL_DTBS
 	bool "Build all Device Tree Blobs"
 	depends on COMPILE_TEST
diff --git a/drivers/of/Makefile b/drivers/of/Makefile
index df305348d1cb..251d33532148 100644
--- a/drivers/of/Makefile
+++ b/drivers/of/Makefile
@@ -19,4 +19,6 @@ obj-y	+= kexec.o
 endif
 endif
 
+obj-$(CONFIG_OF_KUNIT_TEST) += of_test.o
+
 obj-$(CONFIG_OF_UNITTEST) += unittest-data/
diff --git a/drivers/of/of_test.c b/drivers/of/of_test.c
new file mode 100644
index 000000000000..a9301d293f01
--- /dev/null
+++ b/drivers/of/of_test.c
@@ -0,0 +1,57 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KUnit tests for OF APIs
+ */
+#include <linux/module.h>
+#include <linux/of.h>
+
+#include <kunit/test.h>
+
+/*
+ * Test that the root node "/" can be found by path.
+ */
+static void of_dtb_root_node_found_by_path(struct kunit *test)
+{
+	struct device_node *np;
+
+	np = of_find_node_by_path("/");
+	KUNIT_EXPECT_NOT_ERR_OR_NULL(test, np);
+	of_node_put(np);
+}
+
+/*
+ * Test that the 'of_root' global variable is always populated when DT code is
+ * enabled. Remove this test once of_root is removed from global access.
+ */
+static void of_dtb_root_node_populates_of_root(struct kunit *test)
+{
+	KUNIT_EXPECT_NOT_ERR_OR_NULL(test, of_root);
+}
+
+static struct kunit_case of_dtb_test_cases[] = {
+	KUNIT_CASE(of_dtb_root_node_found_by_path),
+	KUNIT_CASE(of_dtb_root_node_populates_of_root),
+	{}
+};
+
+static int of_dtb_test_init(struct kunit *test)
+{
+	if (!IS_ENABLED(CONFIG_OF_EARLY_FLATTREE))
+		kunit_skip(test, "requires CONFIG_OF_EARLY_FLATTREE");
+
+	return 0;
+}
+
+/*
+ * Test suite to confirm a DTB is loaded.
+ */
+static struct kunit_suite of_dtb_suite = {
+	.name = "of_dtb",
+	.test_cases = of_dtb_test_cases,
+	.init = of_dtb_test_init,
+};
+
+kunit_test_suites(
+	&of_dtb_suite,
+);
+MODULE_LICENSE("GPL");
-- 
https://git.kernel.org/pub/scm/linux/kernel/git/clk/linux.git/
https://git.kernel.org/pub/scm/linux/kernel/git/sboyd/spmi.git

Re: [PATCH v4 5/7] arm64: Unconditionally call unflatten_device_tree()

[Rob Herring]

On Fri, Feb 16, 2024 at 05:05:54PM -0800, Stephen Boyd wrote:
> Call this function unconditionally so that we can populate an empty DTB
> on platforms that don't boot with a firmware provided or builtin DTB.
> When ACPI is in use, unflatten_device_tree() ignores the
> 'initial_boot_params' pointer so the live DT on those systems won't be
> whatever that's pointing to. Similarly, when kexec copies the DT data
> the previous kernel to the new one on ACPI systems,
> of_kexec_alloc_and_setup_fdt() will ignore the live DT (the empty root
> one) and copy the 'initial_boot_params' data.
> 
> Cc: Rob Herring <robh+dt@kernel.org>
> Cc: Frank Rowand <frowand.list@gmail.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: <linux-arm-kernel@lists.infradead.org>
> Signed-off-by: Stephen Boyd <sboyd@kernel.org>
> ---
>  arch/arm64/kernel/setup.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)

Catalin, Will, Can I get an ack on this so I can take the series via the 
DT tree.

Rob

Re: [PATCH v4 5/7] arm64: Unconditionally call unflatten_device_tree()

[Will Deacon]

On Thu, Feb 22, 2024 at 05:03:17PM -0700, Rob Herring wrote:
> On Fri, Feb 16, 2024 at 05:05:54PM -0800, Stephen Boyd wrote:
> > Call this function unconditionally so that we can populate an empty DTB
> > on platforms that don't boot with a firmware provided or builtin DTB.
> > When ACPI is in use, unflatten_device_tree() ignores the
> > 'initial_boot_params' pointer so the live DT on those systems won't be
> > whatever that's pointing to. Similarly, when kexec copies the DT data
> > the previous kernel to the new one on ACPI systems,
> > of_kexec_alloc_and_setup_fdt() will ignore the live DT (the empty root
> > one) and copy the 'initial_boot_params' data.
> > 
> > Cc: Rob Herring <robh+dt@kernel.org>
> > Cc: Frank Rowand <frowand.list@gmail.com>
> > Cc: Catalin Marinas <catalin.marinas@arm.com>
> > Cc: Will Deacon <will@kernel.org>
> > Cc: Mark Rutland <mark.rutland@arm.com>
> > Cc: <linux-arm-kernel@lists.infradead.org>
> > Signed-off-by: Stephen Boyd <sboyd@kernel.org>
> > ---
> >  arch/arm64/kernel/setup.c | 3 +--
> >  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> Catalin, Will, Can I get an ack on this so I can take the series via the 
> DT tree.

Mark had strong pretty strong objections to this in version one:

https://lore.kernel.org/all/ZaZtbU9hre3YhZam@FVFF77S0Q05N/

and this patch looks the same now as it did then. Did something else
change?

Will

Re: [PATCH v4 5/7] arm64: Unconditionally call unflatten_device_tree()

[Rob Herring]

On Fri, Feb 23, 2024 at 3:23 AM Will Deacon <will@kernel.org> wrote:
>
> On Thu, Feb 22, 2024 at 05:03:17PM -0700, Rob Herring wrote:
> > On Fri, Feb 16, 2024 at 05:05:54PM -0800, Stephen Boyd wrote:
> > > Call this function unconditionally so that we can populate an empty DTB
> > > on platforms that don't boot with a firmware provided or builtin DTB.
> > > When ACPI is in use, unflatten_device_tree() ignores the
> > > 'initial_boot_params' pointer so the live DT on those systems won't be
> > > whatever that's pointing to. Similarly, when kexec copies the DT data
> > > the previous kernel to the new one on ACPI systems,
> > > of_kexec_alloc_and_setup_fdt() will ignore the live DT (the empty root
> > > one) and copy the 'initial_boot_params' data.
> > >
> > > Cc: Rob Herring <robh+dt@kernel.org>
> > > Cc: Frank Rowand <frowand.list@gmail.com>
> > > Cc: Catalin Marinas <catalin.marinas@arm.com>
> > > Cc: Will Deacon <will@kernel.org>
> > > Cc: Mark Rutland <mark.rutland@arm.com>
> > > Cc: <linux-arm-kernel@lists.infradead.org>
> > > Signed-off-by: Stephen Boyd <sboyd@kernel.org>
> > > ---
> > >  arch/arm64/kernel/setup.c | 3 +--
> > >  1 file changed, 1 insertion(+), 2 deletions(-)
> >
> > Catalin, Will, Can I get an ack on this so I can take the series via the
> > DT tree.
>
> Mark had strong pretty strong objections to this in version one:

Yes, I had concerns with it as well.

> https://lore.kernel.org/all/ZaZtbU9hre3YhZam@FVFF77S0Q05N/
>
> and this patch looks the same now as it did then. Did something else
> change?

Yes, that version unflattened the bootloader passed DT. Now within
unflatten_devicetree(), the bootloader DT is ignored if ACPI is
enabled and we unflatten an empty tree. That will prevent the kernel
getting 2 h/w descriptions if/when a platform does such a thing. Also,
kexec still uses the bootloader provided DT as before.

Rob

Re: [PATCH v4 5/7] arm64: Unconditionally call unflatten_device_tree()

[Oreoluwa Babatunde]

On 2/16/2024 5:05 PM, Stephen Boyd wrote:

> Call this function unconditionally so that we can populate an empty DTB
> on platforms that don't boot with a firmware provided or builtin DTB.
> When ACPI is in use, unflatten_device_tree() ignores the
> 'initial_boot_params' pointer so the live DT on those systems won't be
> whatever that's pointing to. Similarly, when kexec copies the DT data
> the previous kernel to the new one on ACPI systems,
> of_kexec_alloc_and_setup_fdt() will ignore the live DT (the empty root
> one) and copy the 'initial_boot_params' data.
>
> Cc: Rob Herring <robh+dt@kernel.org>
> Cc: Frank Rowand <frowand.list@gmail.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: <linux-arm-kernel@lists.infradead.org>
> Signed-off-by: Stephen Boyd <sboyd@kernel.org>

This change looks good to me. I am working on a patch set that will benefit from this.
Reviewed-by: Oreoluwa Babatunde <quic_obabatun@quicinc.com>

Regards,
Oreoluwa

> ---
>  arch/arm64/kernel/setup.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
> index 42c690bb2d60..0d210720d47d 100644
> --- a/arch/arm64/kernel/setup.c
> +++ b/arch/arm64/kernel/setup.c
> @@ -351,8 +351,7 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p)
>  	/* Parse the ACPI tables for possible boot-time configuration */
>  	acpi_boot_table_init();
>  
> -	if (acpi_disabled)
> -		unflatten_device_tree();
> +	unflatten_device_tree();
>  
>  	bootmem_init();

Re: [PATCH v4 5/7] arm64: Unconditionally call unflatten_device_tree()

[Mark Rutland]

On Fri, Feb 23, 2024 at 11:17:02AM -0700, Rob Herring wrote:
> On Fri, Feb 23, 2024 at 3:23 AM Will Deacon <will@kernel.org> wrote:
> >
> > On Thu, Feb 22, 2024 at 05:03:17PM -0700, Rob Herring wrote:
> > > On Fri, Feb 16, 2024 at 05:05:54PM -0800, Stephen Boyd wrote:
> > > > Call this function unconditionally so that we can populate an empty DTB
> > > > on platforms that don't boot with a firmware provided or builtin DTB.
> > > > When ACPI is in use, unflatten_device_tree() ignores the
> > > > 'initial_boot_params' pointer so the live DT on those systems won't be
> > > > whatever that's pointing to. Similarly, when kexec copies the DT data
> > > > the previous kernel to the new one on ACPI systems,
> > > > of_kexec_alloc_and_setup_fdt() will ignore the live DT (the empty root
> > > > one) and copy the 'initial_boot_params' data.
> > > >
> > > > Cc: Rob Herring <robh+dt@kernel.org>
> > > > Cc: Frank Rowand <frowand.list@gmail.com>
> > > > Cc: Catalin Marinas <catalin.marinas@arm.com>
> > > > Cc: Will Deacon <will@kernel.org>
> > > > Cc: Mark Rutland <mark.rutland@arm.com>
> > > > Cc: <linux-arm-kernel@lists.infradead.org>
> > > > Signed-off-by: Stephen Boyd <sboyd@kernel.org>
> > > > ---
> > > >  arch/arm64/kernel/setup.c | 3 +--
> > > >  1 file changed, 1 insertion(+), 2 deletions(-)
> > >
> > > Catalin, Will, Can I get an ack on this so I can take the series via the
> > > DT tree.
> >
> > Mark had strong pretty strong objections to this in version one:
> 
> Yes, I had concerns with it as well.
> 
> > https://lore.kernel.org/all/ZaZtbU9hre3YhZam@FVFF77S0Q05N/
> >
> > and this patch looks the same now as it did then. Did something else
> > change?
> 
> Yes, that version unflattened the bootloader passed DT. Now within
> unflatten_devicetree(), the bootloader DT is ignored if ACPI is
> enabled and we unflatten an empty tree. That will prevent the kernel
> getting 2 h/w descriptions if/when a platform does such a thing. Also,
> kexec still uses the bootloader provided DT as before.

That avoids the main instance of my concern, and means that this'll boot
without issue, but IIUC this opens the door to dynamically instantiating DT
devices atop an ACPI base system, which I think in general is something that's
liable to cause more problems than it solves.

I understand that's desireable for the selftests, though I still don't believe
it's strictly necessary -- there are plenty of other things that only work if
the kernel is booted in a specific configuration.

Putting the selftests aside, why do we need to do this? Is there any other
reason to enable this?

Mark.

Re: [PATCH v4 5/7] arm64: Unconditionally call unflatten_device_tree()

[Rob Herring]

On Tue, Feb 27, 2024 at 05:34:58PM +0000, Mark Rutland wrote:
> On Fri, Feb 23, 2024 at 11:17:02AM -0700, Rob Herring wrote:
> > On Fri, Feb 23, 2024 at 3:23 AM Will Deacon <will@kernel.org> wrote:
> > >
> > > On Thu, Feb 22, 2024 at 05:03:17PM -0700, Rob Herring wrote:
> > > > On Fri, Feb 16, 2024 at 05:05:54PM -0800, Stephen Boyd wrote:
> > > > > Call this function unconditionally so that we can populate an empty DTB
> > > > > on platforms that don't boot with a firmware provided or builtin DTB.
> > > > > When ACPI is in use, unflatten_device_tree() ignores the
> > > > > 'initial_boot_params' pointer so the live DT on those systems won't be
> > > > > whatever that's pointing to. Similarly, when kexec copies the DT data
> > > > > the previous kernel to the new one on ACPI systems,
> > > > > of_kexec_alloc_and_setup_fdt() will ignore the live DT (the empty root
> > > > > one) and copy the 'initial_boot_params' data.
> > > > >
> > > > > Cc: Rob Herring <robh+dt@kernel.org>
> > > > > Cc: Frank Rowand <frowand.list@gmail.com>
> > > > > Cc: Catalin Marinas <catalin.marinas@arm.com>
> > > > > Cc: Will Deacon <will@kernel.org>
> > > > > Cc: Mark Rutland <mark.rutland@arm.com>
> > > > > Cc: <linux-arm-kernel@lists.infradead.org>
> > > > > Signed-off-by: Stephen Boyd <sboyd@kernel.org>
> > > > > ---
> > > > >  arch/arm64/kernel/setup.c | 3 +--
> > > > >  1 file changed, 1 insertion(+), 2 deletions(-)
> > > >
> > > > Catalin, Will, Can I get an ack on this so I can take the series via the
> > > > DT tree.
> > >
> > > Mark had strong pretty strong objections to this in version one:
> > 
> > Yes, I had concerns with it as well.
> > 
> > > https://lore.kernel.org/all/ZaZtbU9hre3YhZam@FVFF77S0Q05N/
> > >
> > > and this patch looks the same now as it did then. Did something else
> > > change?
> > 
> > Yes, that version unflattened the bootloader passed DT. Now within
> > unflatten_devicetree(), the bootloader DT is ignored if ACPI is
> > enabled and we unflatten an empty tree. That will prevent the kernel
> > getting 2 h/w descriptions if/when a platform does such a thing. Also,
> > kexec still uses the bootloader provided DT as before.
> 
> That avoids the main instance of my concern, and means that this'll boot
> without issue, but IIUC this opens the door to dynamically instantiating DT
> devices atop an ACPI base system, which I think in general is something that's
> liable to cause more problems than it solves.
> 
> I understand that's desireable for the selftests, though I still don't believe
> it's strictly necessary -- there are plenty of other things that only work if
> the kernel is booted in a specific configuration.

Why add to the test matrix if we don't have to?

> Putting the selftests aside, why do we need to do this? Is there any other
> reason to enable this?

See my Plumbers talk...

Or in short, there's 3 main usecases:

- PCI FPGA card with devices instantiated in it 
- SoCs which expose their peripherals via a PCI endpoint.
- Injecting test devices with QEMU (testing, but not what this series 
  does. Jonathan Cameron's usecase)

In all cases, drivers already exist for the devices, and they often only 
support DT. DT overlays is the natural solution for this, and there's 
now kernel support for it (dynamically generating PCI DT nodes when they 
don't exist). The intent is to do the same thing on ACPI systems.

I don't see another solution other than 'go away, you're crazy'. There's 
ACPI overlays, but that's only a debug feature. Also, that would 
encourage more of the DT bindings in ACPI which I find worse than this 
mixture. There's swnodes, but that's just board files and platform_data 
2.0.

I share the concerns with mixing, but I don't see a better solution. The 
scope of what's possible is contained enough to avoid issues.

Rob

Re: [PATCH v4 5/7] arm64: Unconditionally call unflatten_device_tree()

[Herve Codina]

Hi,

On Wed, 28 Feb 2024 10:26:47 -0600
Rob Herring <robh@kernel.org> wrote:

...
> > > 
> > > Yes, that version unflattened the bootloader passed DT. Now within
> > > unflatten_devicetree(), the bootloader DT is ignored if ACPI is
> > > enabled and we unflatten an empty tree. That will prevent the kernel
> > > getting 2 h/w descriptions if/when a platform does such a thing. Also,
> > > kexec still uses the bootloader provided DT as before.  
> > 
> > That avoids the main instance of my concern, and means that this'll boot
> > without issue, but IIUC this opens the door to dynamically instantiating DT
> > devices atop an ACPI base system, which I think in general is something that's
> > liable to cause more problems than it solves.
> > 
> > I understand that's desireable for the selftests, though I still don't believe
> > it's strictly necessary -- there are plenty of other things that only work if
> > the kernel is booted in a specific configuration.  
> 
> Why add to the test matrix if we don't have to?
> 
> > Putting the selftests aside, why do we need to do this? Is there any other
> > reason to enable this?  
> 
> See my Plumbers talk...
> 
> Or in short, there's 3 main usecases:
> 
> - PCI FPGA card with devices instantiated in it 
> - SoCs which expose their peripherals via a PCI endpoint.
> - Injecting test devices with QEMU (testing, but not what this series 
>   does. Jonathan Cameron's usecase)
> 
> In all cases, drivers already exist for the devices, and they often only 
> support DT. DT overlays is the natural solution for this, and there's 
> now kernel support for it (dynamically generating PCI DT nodes when they 
> don't exist). The intent is to do the same thing on ACPI systems.
> 
> I don't see another solution other than 'go away, you're crazy'. There's 
> ACPI overlays, but that's only a debug feature. Also, that would 
> encourage more of the DT bindings in ACPI which I find worse than this 
> mixture. There's swnodes, but that's just board files and platform_data 
> 2.0.
> 
> I share the concerns with mixing, but I don't see a better solution. The 
> scope of what's possible is contained enough to avoid issues.
> 

I tested on a x86 system.
My use case is 'SoCs which expose their peripherals via a PCI endpoint'
described by Rob.
Indeed, I have a Microchip Lan9662 board (the one mentioned by Rob in his
Plumbers talk) and the root DT node creation is obviously needed.

I have previously used Frank Rowan's patches [1] that did this DT root node
creation. This series perfectly replace them and the root DT node is successfully
created.

Tested-by: Herve Codina <herve.codina@bootlin.com>

[1]: https://lore.kernel.org/all/20230317053415.2254616-1-frowand.list@gmail.com/

Best regards,
Hervé Codina
-- 
Hervé Codina, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH v4 0/7] of: populate of_root node if bootloader doesn't

[Rob Herring]

On Fri, Feb 16, 2024 at 05:05:49PM -0800, Stephen Boyd wrote:
> Arch maintainers, please ack/review patches.
> 
> This is a resend of a series from Frank last year[1]. I worked in Rob's
> review comments to unconditionally call unflatten_device_tree() and
> fixup/audit calls to of_have_populated_dt() so that behavior doesn't
> change.
> 
> I need this series so I can add DT based tests in the clk framework.
> Either I can merge it through the clk tree once everyone is happy, or
> Rob can merge it through the DT tree and provide some branch so I can
> base clk patches on it.
> 
> Changes from v3 (https://lore.kernel.org/r/20240202195909.3458162-1-sboyd@kernel.org):
>  * Made OF_UNITTEST depend on OF_EARLY_FLATREE
>  * Made OF_EARLY_FLATREE depend on absence of arches that don't call
>    unflatten_device_tree()
>  * Added of_ prefix to dtb_ prefixed KUnit tests
>  * Picked up tags
> 
> Changes from v2 (https://lore.kernel.org/r/20240130004508.1700335-1-sboyd@kernel.org):
>  * Reorder patches to have OF changes largely first
>  * No longer modify initial_boot_params if ACPI=y
>  * Put arm64 patch back to v1
> 
> Changes from v1 (https://lore.kernel.org/r/20240112200750.4062441-1-sboyd@kernel.org):
>  * x86 patch included
>  * arm64 knocks out initial dtb if acpi is in use
>  * keep Kconfig hidden but def_bool enabled otherwise
> 
> Changes from Frank's series[1]:
>  * Add a DTB loaded kunit test
>  * Make of_have_populated_dt() return false if the DTB isn't from the
>    bootloader
>  * Architecture calls made unconditional so that a root node is always
>    made
> 
> Frank Rowand (2):
>   of: Create of_root if no dtb provided by firmware
>   of: unittest: treat missing of_root as error instead of fixing up
> 
> Stephen Boyd (5):
>   of: Always unflatten in unflatten_and_copy_device_tree()
>   um: Unconditionally call unflatten_device_tree()
>   x86/of: Unconditionally call unflatten_and_copy_device_tree()
>   arm64: Unconditionally call unflatten_device_tree()
>   of: Add KUnit test to confirm DTB is loaded

I've applied the series minus the arm64 patch. It's only needed if 
anyone cares about this working on arm64 ACPI systems. That can be delt 
with separately.

Rob