[PATCH 3/7] microblaze: Define SMP safe bit operations

[Michal Simek <michal.simek@xilinx.com>]

From: Stefan Asserhall <stefan.asserhall@xilinx.com>

For SMP based system there is a need to have proper bit operations.
Microblaze is using exclusive load and store instructions.

Signed-off-by: Stefan Asserhall <stefan.asserhall@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
---

 arch/microblaze/include/asm/Kbuild   |   1 -
 arch/microblaze/include/asm/bitops.h | 189 +++++++++++++++++++++++++++
 2 files changed, 189 insertions(+), 1 deletion(-)
 create mode 100644 arch/microblaze/include/asm/bitops.h

diff --git a/arch/microblaze/include/asm/Kbuild b/arch/microblaze/include/asm/Kbuild
index abb33619299b..0da195308ac9 100644
--- a/arch/microblaze/include/asm/Kbuild
+++ b/arch/microblaze/include/asm/Kbuild
@@ -1,6 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0
 generated-y += syscall_table.h
-generic-y += bitops.h
 generic-y += bug.h
 generic-y += bugs.h
 generic-y += compat.h
diff --git a/arch/microblaze/include/asm/bitops.h b/arch/microblaze/include/asm/bitops.h
new file mode 100644
index 000000000000..a4f5ca09850f
--- /dev/null
+++ b/arch/microblaze/include/asm/bitops.h
@@ -0,0 +1,189 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Microblaze atomic bit operations.
+ *
+ * Copyright (C) 2013 - 2020 Xilinx, Inc.
+ *
+ * Merged version by David Gibson <david@gibson.dropbear.id.au>.
+ * Based on ppc64 versions by: Dave Engebretsen, Todd Inglett, Don
+ * Reed, Pat McCarthy, Peter Bergner, Anton Blanchard.  They
+ * originally took it from the ppc32 code.
+ *
+ * Within a word, bits are numbered LSB first.  Lot's of places make
+ * this assumption by directly testing bits with (val & (1<<nr)).
+ * This can cause confusion for large (> 1 word) bitmaps on a
+ * big-endian system because, unlike little endian, the number of each
+ * bit depends on the word size.
+ *
+ * The bitop functions are defined to work on unsigned longs, so for a
+ * ppc64 system the bits end up numbered:
+ *   |63..............0|127............64|191...........128|255...........196|
+ * and on ppc32:
+ *   |31.....0|63....31|95....64|127...96|159..128|191..160|223..192|255..224|
+ *
+ * There are a few little-endian macros used mostly for filesystem
+ * bitmaps, these work on similar bit arrays layouts, but
+ * byte-oriented:
+ *   |7...0|15...8|23...16|31...24|39...32|47...40|55...48|63...56|
+ *
+ * The main difference is that bit 3-5 (64b) or 3-4 (32b) in the bit
+ * number field needs to be reversed compared to the big-endian bit
+ * fields. This can be achieved by XOR with 0x38 (64b) or 0x18 (32b).
+ */
+
+#ifndef _ASM_MICROBLAZE_BITOPS_H
+#define _ASM_MICROBLAZE_BITOPS_H
+
+#ifndef _LINUX_BITOPS_H
+#error only <linux/bitops.h> can be included directly
+#endif
+
+#include <asm/types.h>
+#include <linux/compiler.h>
+#include <asm/asm-compat.h>
+#include <linux/stringify.h>
+
+/*
+ * clear_bit doesn't imply a memory barrier
+ */
+#define smp_mb__before_clear_bit()	smp_mb()
+#define smp_mb__after_clear_bit()	smp_mb()
+
+#define BITOP_MASK(nr)		(1UL << ((nr) % BITS_PER_LONG))
+#define BITOP_WORD(nr)		((nr) / BITS_PER_LONG)
+
+/* Macro for generating the ***_bits() functions */
+#define DEFINE_BITOP(fn, op)						\
+static inline void fn(unsigned long mask, volatile unsigned long *_p)	\
+{									\
+	unsigned long tmp;						\
+	unsigned long *p = (unsigned long *)_p;				\
+									\
+	__asm__ __volatile__ (						\
+		/* load conditional address in %2 to %0 */		\
+		"1:	lwx		%0, %3, r0;\n"			\
+		/* perform bit operation with mask */			\
+		stringify_in_c(op)"	%0, %0, %2;\n"			\
+		/* attempt store */					\
+		"	swx		%0, %3, r0;\n"			\
+		/* checking msr carry flag */				\
+		"	addic		%0, r0, 0;\n"			\
+		/* store failed (MSR[C] set)? try again */		\
+		"	bnei		%0, 1b;\n"			\
+		: "=&r" (tmp), "+m" (*p)  /* Outputs: tmp, p */		\
+		: "r" (mask), "r" (p)     /* Inputs: mask, p */		\
+		: "cc", "memory"					\
+	);								\
+}
+
+DEFINE_BITOP(set_bits, or)
+DEFINE_BITOP(clear_bits, andn)
+DEFINE_BITOP(clear_bits_unlock, andn)
+DEFINE_BITOP(change_bits, xor)
+
+static inline void set_bit(int nr, volatile unsigned long *addr)
+{
+	set_bits(BITOP_MASK(nr), addr + BITOP_WORD(nr));
+}
+
+static inline void clear_bit(int nr, volatile unsigned long *addr)
+{
+	clear_bits(BITOP_MASK(nr), addr + BITOP_WORD(nr));
+}
+
+static inline void clear_bit_unlock(int nr, volatile unsigned long *addr)
+{
+	clear_bits_unlock(BITOP_MASK(nr), addr + BITOP_WORD(nr));
+}
+
+static inline void change_bit(int nr, volatile unsigned long *addr)
+{
+	change_bits(BITOP_MASK(nr), addr + BITOP_WORD(nr));
+}
+
+/*
+ * Like DEFINE_BITOP(), with changes to the arguments to 'op' and the output
+ * operands.
+ */
+#define DEFINE_TESTOP(fn, op)						\
+static inline unsigned long fn(unsigned long mask,			\
+			       volatile unsigned long *_p)		\
+{									\
+	unsigned long old, tmp;						\
+	unsigned long *p = (unsigned long *)_p;				\
+									\
+	__asm__ __volatile__ (						\
+		/* load conditional address in %4 to %0 */		\
+		"1:	lwx		%0, %4, r0;\n"			\
+		/* perform bit operation with mask */			\
+		stringify_in_c(op)"	%1, %0, %3;\n"			\
+		/* attempt store */					\
+		"	swx		%1, %4, r0;\n"			\
+		/* checking msr carry flag */				\
+		"	addic		%1, r0, 0;\n"			\
+		/* store failed (MSR[C] set)? try again */		\
+		"	bnei		%1, 1b;\n"			\
+		/* Outputs: old, tmp, p */				\
+		: "=&r" (old), "=&r" (tmp), "+m" (*p)			\
+		 /* Inputs: mask, p */					\
+		: "r" (mask), "r" (p)					\
+		: "cc", "memory"					\
+	);								\
+	return (old & mask);						\
+}
+
+DEFINE_TESTOP(test_and_set_bits, or)
+DEFINE_TESTOP(test_and_set_bits_lock, or)
+DEFINE_TESTOP(test_and_clear_bits, andn)
+DEFINE_TESTOP(test_and_change_bits, xor)
+
+static inline int test_and_set_bit(unsigned long nr,
+				       volatile unsigned long *addr)
+{
+	return test_and_set_bits(BITOP_MASK(nr), addr + BITOP_WORD(nr)) != 0;
+}
+
+static inline int test_and_set_bit_lock(unsigned long nr,
+				       volatile unsigned long *addr)
+{
+	return test_and_set_bits_lock(BITOP_MASK(nr),
+				addr + BITOP_WORD(nr)) != 0;
+}
+
+static inline int test_and_clear_bit(unsigned long nr,
+					 volatile unsigned long *addr)
+{
+	return test_and_clear_bits(BITOP_MASK(nr), addr + BITOP_WORD(nr)) != 0;
+}
+
+static inline int test_and_change_bit(unsigned long nr,
+					  volatile unsigned long *addr)
+{
+	return test_and_change_bits(BITOP_MASK(nr), addr + BITOP_WORD(nr)) != 0;
+}
+
+#include <asm-generic/bitops/non-atomic.h>
+
+static inline void __clear_bit_unlock(int nr, volatile unsigned long *addr)
+{
+	__clear_bit(nr, addr);
+}
+
+#include <asm-generic/bitops/ffz.h>
+#include <asm-generic/bitops/__fls.h>
+#include <asm-generic/bitops/__ffs.h>
+#include <asm-generic/bitops/fls.h>
+#include <asm-generic/bitops/ffs.h>
+#include <asm-generic/bitops/hweight.h>
+#include <asm-generic/bitops/find.h>
+#include <asm-generic/bitops/fls64.h>
+
+/* Little-endian versions */
+#include <asm-generic/bitops/le.h>
+
+/* Bitmap functions for the ext2 filesystem */
+#include <asm-generic/bitops/ext2-atomic-setbit.h>
+
+#include <asm-generic/bitops/sched.h>
+
+#endif /* _ASM_MICROBLAZE_BITOPS_H */
-- 
2.25.0