Merge patch series "Linux compat improvements and CCF prep"

Casey Connolly <[email protected]> says:

This series implements various improvements to Linux header
compatibility, largely in preparation for a full port of Linux CCF but
many of these changes would also be helpful when porting other drivers.

Beside the basic header/compat stuff there are a few larger patches:

Patch 1 adds the "%pOF" format specifier to vsprintf, this behaves the
same as it does in Linux printing the name of the ofnode, but notably it
expects an ofnode pointer rather than a device_node.

Patch 2 adds an option to skip doing a full DM scan pre-relocation.
Some platforms like Qualcomm don't actually need devices to be probed
prior to relocation, it is also quite slow to scan the entire FDT before
caches are up. This option gets us to main loop 30-50% faster.

Unfortunately it isn't possible to totally skip DM since U-Boot will
panic if it can't find a serial port, but the serial uclass code will
bind the serial port itself by reading /chosen/stdout-path, however any
dependencies like clocks won't be found so this should only be enabled
if the serial driver gracefully handles missing clocks.

Patch 3 adds [k]strdup_const(), this works the same as the Linux version
saving a small amount of memory by avoiding duplicating strings stored
in .rodata, this is particularly useful for CCF.

Patch 4 adds 64-bit versions of some 32-bit ofnode utilities functions,
making it possible to parse 64-bit arrays.

Patch 6 provides a simple implementation of kref, this will be used
by CCF.

Patch 9 adds devm_krealloc() support to devres, it relies on storing
allocation sizes in the devres struct which will add a small overhead.

Link: https://lore.kernel.org/r/[email protected]

7 files changed, 213 insertions, 0 deletions

diff --git a/include/linux/compat.h b/include/linux/compat.h
index 62381451617..d4ba4d0088a 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -67,6 +67,19 @@ static inline void vfree(const void *addr)
 	free((void *)addr);
 }
 
+/**
+ * kstrdup_const - conditionally duplicate an existing const string
+ * @s: the string to duplicate
+ * @gfp: the GFP mask used in the kmalloc() call when allocating memory
+ *
+ * Note: Strings allocated by kstrdup_const should be freed by kfree_const and
+ * must not be passed to krealloc().
+ *
+ * Return: source string if it is in .rodata section otherwise
+ * fallback to kstrdup.
+ */
+#define kstrdup_const(s, gfp) strdup_const(s)
+
 struct kmem_cache { int sz; };
 
 struct kmem_cache *get_mem(int element_sz);
diff --git a/include/linux/device.h b/include/linux/device.h
new file mode 100644
index 00000000000..e76635cfde9
--- /dev/null
+++ b/include/linux/device.h
@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * device.h - generic, centralized driver model
+ *
+ * U-Boot: compat header derived from Linux
+ *
+ * Copyright (c) 2001-2003 Patrick Mochel <[email protected]>
+ * Copyright (c) 2004-2009 Greg Kroah-Hartman <[email protected]>
+ * Copyright (c) 2008-2009 Novell Inc.
+ *
+ * See Documentation/driver-api/driver-model/ for more information.
+ */
+
+#ifndef _DEVICE_H_
+#define _DEVICE_H_
+
+#include <dm/device.h>
+
+/**
+ * dev_name - Return a device's name.
+ * @dev: Device with name to get.
+ * Return: The kobject name of the device, or its initial name if unavailable.
+ */
+static inline const char *dev_name(const struct udevice *dev)
+{
+	return dev->name;
+}
+
+#endif /* _DEVICE_H_ */
diff --git a/include/linux/err.h b/include/linux/err.h
index 7a0b212c813..2463c4611b2 100644
--- a/include/linux/err.h
+++ b/include/linux/err.h
@@ -53,6 +53,31 @@ static inline void * __must_check ERR_CAST(__force const void *ptr)
 	return (void *) ptr;
 }
 
+/**
+ * PTR_ERR_OR_ZERO - Extract the error code from a pointer if it has one.
+ * @ptr: A potential error pointer.
+ *
+ * Convenience function that can be used inside a function that returns
+ * an error code to propagate errors received as error pointers.
+ * For example, ``return PTR_ERR_OR_ZERO(ptr);`` replaces:
+ *
+ * .. code-block:: c
+ *
+ *	if (IS_ERR(ptr))
+ *		return PTR_ERR(ptr);
+ *	else
+ *		return 0;
+ *
+ * Return: The error code within @ptr if it is an error pointer; 0 otherwise.
+ */
+static inline int __must_check PTR_ERR_OR_ZERO(__force const void *ptr)
+{
+	if (IS_ERR(ptr))
+		return PTR_ERR(ptr);
+	else
+		return 0;
+}
+
 #endif
 
 #endif /* _LINUX_ERR_H */
diff --git a/include/linux/kref.h b/include/linux/kref.h
new file mode 100644
index 00000000000..30927047d54
--- /dev/null
+++ b/include/linux/kref.h
@@ -0,0 +1,124 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * kref.h - library routines for handling generic reference counted objects
+ *
+ * Copyright (C) 2004 Greg Kroah-Hartman <[email protected]>
+ * Copyright (C) 2004 IBM Corp.
+ *
+ * based on kobject.h which was:
+ * Copyright (C) 2002-2003 Patrick Mochel <[email protected]>
+ * Copyright (C) 2002-2003 Open Source Development Labs
+ */
+
+#ifndef _KREF_H_
+#define _KREF_H_
+
+#include <linux/compat.h>
+
+struct kref {
+	long refcount;
+};
+
+#define KREF_INIT(n)	{ .refcount = REFCOUNT_INIT(n), }
+
+/**
+ * kref_init - initialize object.
+ * @kref: object in question.
+ */
+static inline void kref_init(struct kref *kref)
+{
+	kref->refcount = 1;
+}
+
+static inline unsigned int kref_read(const struct kref *kref)
+{
+	return kref->refcount;
+}
+
+/**
+ * kref_get - increment refcount for object.
+ * @kref: object.
+ */
+static inline void kref_get(struct kref *kref)
+{
+	kref->refcount++;
+}
+
+/**
+ * kref_put - Decrement refcount for object
+ * @kref: Object
+ * @release: Pointer to the function that will clean up the object when the
+ *	     last reference to the object is released.
+ *
+ * Decrement the refcount, and if 0, call @release.  The caller may not
+ * pass NULL or kfree() as the release function.
+ *
+ * Return: 1 if this call removed the object, otherwise return 0.  Beware,
+ * if this function returns 0, another caller may have removed the object
+ * by the time this function returns.  The return value is only certain
+ * if you want to see if the object is definitely released.
+ */
+static inline int kref_put(struct kref *kref, void (*release)(struct kref *kref))
+{
+	if (--kref->refcount == 0) {
+		release(kref);
+		return 1;
+	}
+	return 0;
+}
+
+/**
+ * kref_put_mutex - Decrement refcount for object
+ * @kref: Object
+ * @release: Pointer to the function that will clean up the object when the
+ *	     last reference to the object is released.
+ * @mutex: Mutex which protects the release function.
+ *
+ * This variant of kref_lock() calls the @release function with the @mutex
+ * held.  The @release function will release the mutex.
+ */
+static inline int kref_put_mutex(struct kref *kref,
+				 void (*release)(struct kref *kref),
+				 struct mutex *mutex)
+{
+	return kref_put(kref, release);
+}
+
+/**
+ * kref_put_lock - Decrement refcount for object
+ * @kref: Object
+ * @release: Pointer to the function that will clean up the object when the
+ *	     last reference to the object is released.
+ * @lock: Spinlock which protects the release function.
+ *
+ * This variant of kref_lock() calls the @release function with the @lock
+ * held.  The @release function will release the lock.
+ */
+static inline int kref_put_lock(struct kref *kref,
+				void (*release)(struct kref *kref),
+				spinlock_t *lock)
+{
+	return kref_put(kref, release);
+}
+
+/**
+ * kref_get_unless_zero - Increment refcount for object unless it is zero.
+ * @kref: object.
+ *
+ * This function is intended to simplify locking around refcounting for
+ * objects that can be looked up from a lookup structure, and which are
+ * removed from that lookup structure in the object destructor.
+ * Operations on such objects require at least a read lock around
+ * lookup + kref_get, and a write lock around kref_put + remove from lookup
+ * structure. Furthermore, RCU implementations become extremely tricky.
+ * With a lookup followed by a kref_get_unless_zero *with return value check*
+ * locking in the kref_put path can be deferred to the actual removal from
+ * the lookup structure and RCU lookups become trivial.
+ *
+ * Return: non-zero if the increment succeeded. Otherwise return 0.
+ */
+static inline int kref_get_unless_zero(struct kref *kref)
+{
+	return kref->refcount ? kref->refcount++ : 0;
+}
+#endif /* _KREF_H_ */
diff --git a/include/linux/math64.h b/include/linux/math64.h
index eaa9fd5b968..70a7ee3ff1d 100644
--- a/include/linux/math64.h
+++ b/include/linux/math64.h
@@ -257,4 +257,23 @@ static inline u64 mul_u64_u32_div(u64 a, u32 mul, u32 divisor)
 }
 #endif /* mul_u64_u32_div */
 
+/**
+ * abs_diff - return absolute value of the difference between the arguments
+ * @a: the first argument
+ * @b: the second argument
+ *
+ * @a and @b have to be of the same type. With this restriction we compare
+ * signed to signed and unsigned to unsigned. The result is the subtraction
+ * the smaller of the two from the bigger, hence result is always a positive
+ * value.
+ *
+ * Return: an absolute value of the difference between the @a and @b.
+ */
+#define abs_diff(a, b) ({			\
+	typeof(a) __a = (a);			\
+	typeof(b) __b = (b);			\
+	(void)(&__a == &__b);			\
+	__a > __b ? (__a - __b) : (__b - __a);	\
+})
+
 #endif /* _LINUX_MATH64_H */
diff --git a/include/linux/regmap.h b/include/linux/regmap.h
new file mode 120000
index 00000000000..8a3780b5ceb
--- /dev/null
+++ b/include/linux/regmap.h
@@ -0,0 +1 @@
+../regmap.h
\ No newline at end of file
diff --git a/include/linux/string.h b/include/linux/string.h
index d943fcce690..a8a6cf4af50 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -104,6 +104,8 @@ size_t strcspn(const char *s, const char *reject);
 #ifndef __HAVE_ARCH_STRDUP
 extern char * strdup(const char *);
 extern char * strndup(const char *, size_t);
+extern const char *strdup_const(const char *s);
+extern void kfree_const(const void *x);
 #endif
 #ifndef __HAVE_ARCH_STRSWAB
 extern char * strswab(const char *);