1 files changed, 102 insertions, 0 deletions
diff --git a/src/arch/loong64/include/bits/bitops.h b/src/arch/loong64/include/bits/bitops.h
new file mode 100644
index 0000000..6dea29c
--- /dev/null
+++ b/src/arch/loong64/include/bits/bitops.h
@@ -0,0 +1,102 @@
+#ifndef _BITS_BITOPS_H
+#define _BITS_BITOPS_H
+
+/** @file
+ *
+ * loongArch bit operations
+ *
+ * We perform atomic bit set and bit clear operations using "ll"
+ * and "sc".  We use the output constraint to inform the
+ * compiler that any memory from the start of the bit field up to and
+ * including the byte containing the bit may be modified.  (This is
+ * overkill but shouldn't matter in practice since we're unlikely to
+ * subsequently read other bits from the same bit field.)
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
+#include <stdint.h>
+
+/**
+ * Test and set bit atomically
+ *
+ * @v bit		Bit to set
+ * @v bits		Bit field
+ * @ret old		Old value of bit (zero or non-zero)
+ */
+static inline __attribute__ (( always_inline )) int
+test_and_set_bit ( unsigned int bit, volatile void *bits ) {
+	unsigned int index = ( bit / 64 );
+	unsigned int offset = ( bit % 64 );
+	volatile uint64_t *qword = ( ( ( volatile uint64_t * ) bits ) + index );
+	uint64_t mask = ( 1UL << offset );
+	uint64_t old;
+	uint64_t new;
+
+	__asm__ __volatile__ ( "1:				\n\t"
+			       "ll.d %[old], %[qword]		\n\t"
+			       "or   %[new], %[old], %[mask]	\n\t"
+			       "sc.d %[new], %[qword]		\n\t"
+			       "beqz %[new], 1b			\n\t"
+			       : [old] "=&r" ( old ),
+				 [new] "=&r" ( new ),
+				 [qword] "+m" ( *qword )
+			       : [mask] "r" ( mask )
+			       : "cc", "memory");
+	return ( !! ( old & mask ) );
+}
+
+/**
+ * Test and clear bit atomically
+ *
+ * @v bit		Bit to set
+ * @v bits		Bit field
+ * @ret old		Old value of bit (zero or non-zero)
+ */
+static inline __attribute__ (( always_inline )) int
+test_and_clear_bit ( unsigned int bit, volatile void *bits ) {
+	unsigned int index = ( bit / 64 );
+	unsigned int offset = ( bit % 64 );
+	volatile uint64_t *qword = ( ( ( volatile uint64_t * ) bits ) + index );
+	uint64_t mask = ( 1UL << offset );
+	uint64_t old;
+	uint64_t new;
+
+	__asm__ __volatile__ ( "1:				\n\t"
+			       "ll.d %[old], %[qword]		\n\t"
+			       "andn %[new], %[old], %[mask]	\n\t"
+			       "sc.d %[new], %[qword]		\n\t"
+			       "beqz %[new], 1b			\n\t"
+			       : [old] "=&r" ( old ),
+				 [new] "=&r" ( new ),
+				 [qword] "+m" ( *qword )
+			       : [mask] "r" ( mask )
+			       : "cc", "memory");
+	return ( !! ( old & mask ) );
+}
+
+/**
+ * Set bit atomically
+ *
+ * @v bit		Bit to set
+ * @v bits		Bit field
+ */
+static inline __attribute__ (( always_inline )) void
+set_bit ( unsigned int bit, volatile void *bits ) {
+
+	test_and_set_bit ( bit, bits );
+}
+
+/**
+ * Clear bit atomically
+ *
+ * @v bit		Bit to set
+ * @v bits		Bit field
+ */
+static inline __attribute__ (( always_inline )) void
+clear_bit ( unsigned int bit, volatile void *bits ) {
+
+	test_and_clear_bit ( bit, bits );
+}
+
+#endif /* _BITS_BITOPS_H */