csky: Add qspinlock support

Enable qspinlock by the requirements mentioned in a8ad07e5240c9
("asm-generic: qspinlock: Indicate the use of mixed-size atomics").

C-SKY only has "ldex/stex" for all atomic operations. So csky give a
strong forward guarantee for "ldex/stex." That means when ldex grabbed
the cache line into $L1, it would block other cores from snooping the
address with several cycles. The atomic_fetch_add & xchg16 has the same
forward guarantee level in C-SKY.

Qspinlock has better code size and performance in a fast path.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>

diff --git a/arch/csky/Kconfig b/arch/csky/Kconfig
index 41d7d61..333def1 100644 (file)
--- a/arch/csky/Kconfig
+++ b/arch/csky/Kconfig
@@ -8,6 +8,7 @@ config CSKY
        select ARCH_HAS_SYNC_DMA_FOR_DEVICE
        select ARCH_USE_BUILTIN_BSWAP
        select ARCH_USE_QUEUED_RWLOCKS
+       select ARCH_USE_QUEUED_SPINLOCKS
        select ARCH_WANT_FRAME_POINTERS if !CPU_CK610 && $(cc-option,-mbacktrace)
        select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
        select COMMON_CLK

diff --git a/arch/csky/include/asm/Kbuild b/arch/csky/include/asm/Kbuild
index 103207a..1117c28 100644 (file)
--- a/arch/csky/include/asm/Kbuild
+++ b/arch/csky/include/asm/Kbuild
@@ -3,10 +3,10 @@ generic-y += asm-offsets.h
 generic-y += extable.h
 generic-y += gpio.h
 generic-y += kvm_para.h
-generic-y += spinlock.h
-generic-y += spinlock_types.h
+generic-y += mcs_spinlock.h
 generic-y += qrwlock.h
 generic-y += qrwlock_types.h
+generic-y += qspinlock.h
 generic-y += parport.h
 generic-y += user.h
 generic-y += vmlinux.lds.h

diff --git a/arch/csky/include/asm/cmpxchg.h b/arch/csky/include/asm/cmpxchg.h
index 5b8facc..5f693fa 100644 (file)
--- a/arch/csky/include/asm/cmpxchg.h
+++ b/arch/csky/include/asm/cmpxchg.h
@@ -15,6 +15,26 @@ extern void __bad_xchg(void);
        __typeof__(*(ptr)) __ret;                               \
        unsigned long tmp;                                      \
        switch (size) {                                         \
+       case 2: {                                               \
+               u32 ret;                                        \
+               u32 shif = ((ulong)__ptr & 2) ? 16 : 0;         \
+               u32 mask = 0xffff << shif;                      \
+               __ptr = (__typeof__(ptr))((ulong)__ptr & ~2);   \
+               __asm__ __volatile__ (                          \
+                       "1:     ldex.w %0, (%4)\n"              \
+                       "       and    %1, %0, %2\n"            \
+                       "       or     %1, %1, %3\n"            \
+                       "       stex.w %1, (%4)\n"              \
+                       "       bez    %1, 1b\n"                \
+                       : "=&r" (ret), "=&r" (tmp)              \
+                       : "r" (~mask),                          \
+                         "r" ((u32)__new << shif),             \
+                         "r" (__ptr)                           \
+                       : "memory");                            \
+               __ret = (__typeof__(*(ptr)))                    \
+                       ((ret & mask) >> shif);                 \
+               break;                                          \
+       }                                                       \
        case 4:                                                 \
                asm volatile (                                  \
                "1:     ldex.w          %0, (%3) \n"            \

diff --git a/arch/csky/include/asm/spinlock.h b/arch/csky/include/asm/spinlock.h
new file mode 100644 (file)
index 0000000..83a2005
--- /dev/null
+++ b/arch/csky/include/asm/spinlock.h
@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __ASM_CSKY_SPINLOCK_H
+#define __ASM_CSKY_SPINLOCK_H
+
+#include <asm/qspinlock.h>
+#include <asm/qrwlock.h>
+
+/* See include/linux/spinlock.h */
+#define smp_mb__after_spinlock()       smp_mb()
+
+#endif /* __ASM_CSKY_SPINLOCK_H */

diff --git a/arch/csky/include/asm/spinlock_types.h b/arch/csky/include/asm/spinlock_types.h
new file mode 100644 (file)
index 0000000..75bdf3a
--- /dev/null
+++ b/arch/csky/include/asm/spinlock_types.h
@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __ASM_CSKY_SPINLOCK_TYPES_H
+#define __ASM_CSKY_SPINLOCK_TYPES_H
+
+#include <asm-generic/qspinlock_types.h>
+#include <asm-generic/qrwlock_types.h>
+
+#endif /* __ASM_CSKY_SPINLOCK_TYPES_H */