1 files changed, 58 insertions, 0 deletions
diff --git a/arch/parisc/include/asm/ldcw.h b/arch/parisc/include/asm/ldcw.h
new file mode 100644
index 000000000..3eb4bfc1f
--- /dev/null
+++ b/arch/parisc/include/asm/ldcw.h
@@ -0,0 +1,58 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __PARISC_LDCW_H
+#define __PARISC_LDCW_H
+
+#ifndef CONFIG_PA20
+/* Because kmalloc only guarantees 8-byte alignment for kmalloc'd data,
+   and GCC only guarantees 8-byte alignment for stack locals, we can't
+   be assured of 16-byte alignment for atomic lock data even if we
+   specify "__attribute ((aligned(16)))" in the type declaration.  So,
+   we use a struct containing an array of four ints for the atomic lock
+   type and dynamically select the 16-byte aligned int from the array
+   for the semaphore.  */
+
+#define __PA_LDCW_ALIGNMENT	16
+#define __PA_LDCW_ALIGN_ORDER	4
+#define __ldcw_align(a) ({					\
+	unsigned long __ret = (unsigned long) &(a)->lock[0];	\
+	__ret = (__ret + __PA_LDCW_ALIGNMENT - 1)		\
+		& ~(__PA_LDCW_ALIGNMENT - 1);			\
+	(volatile unsigned int *) __ret;			\
+})
+#define __LDCW	"ldcw"
+
+#else /*CONFIG_PA20*/
+/* From: "Jim Hull" <jim.hull of hp.com>
+   I've attached a summary of the change, but basically, for PA 2.0, as
+   long as the ",CO" (coherent operation) completer is specified, then the
+   16-byte alignment requirement for ldcw and ldcd is relaxed, and instead
+   they only require "natural" alignment (4-byte for ldcw, 8-byte for
+   ldcd). */
+
+#define __PA_LDCW_ALIGNMENT	4
+#define __PA_LDCW_ALIGN_ORDER	2
+#define __ldcw_align(a) (&(a)->slock)
+#define __LDCW	"ldcw,co"
+
+#endif /*!CONFIG_PA20*/
+
+/* LDCW, the only atomic read-write operation PA-RISC has. *sigh*.
+   We don't explicitly expose that "*a" may be written as reload
+   fails to find a register in class R1_REGS when "a" needs to be
+   reloaded when generating 64-bit PIC code.  Instead, we clobber
+   memory to indicate to the compiler that the assembly code reads
+   or writes to items other than those listed in the input and output
+   operands.  This may pessimize the code somewhat but __ldcw is
+   usually used within code blocks surrounded by memory barriers.  */
+#define __ldcw(a) ({						\
+	unsigned __ret;						\
+	__asm__ __volatile__(__LDCW " 0(%1),%0"			\
+		: "=r" (__ret) : "r" (a) : "memory");		\
+	__ret;							\
+})
+
+#ifdef CONFIG_SMP
+# define __lock_aligned __attribute__((__section__(".data..lock_aligned")))
+#endif
+
+#endif /* __PARISC_LDCW_H */