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authorLinus Torvalds <torvalds@linux-foundation.org>2019-05-06 16:57:52 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-05-06 16:57:52 -0700
commitdd4e5d6106b2380e2c1238406d26df8b2fe1c42c (patch)
tree33eb172237dd8873de02d5b881bf17cf58d05fab /arch/riscv/include
parent14be4c61c205dcb0a72251c1e2790814181bd9ba (diff)
parent9726840d9cf0d42377e1591263d7c1d9ae0988ac (diff)
Merge tag 'arm64-mmiowb' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull mmiowb removal from Will Deacon: "Remove Mysterious Macro Intended to Obscure Weird Behaviours (mmiowb()) Remove mmiowb() from the kernel memory barrier API and instead, for architectures that need it, hide the barrier inside spin_unlock() when MMIO has been performed inside the critical section. The only relatively recent changes have been addressing review comments on the documentation, which is in a much better shape thanks to the efforts of Ben and Ingo. I was initially planning to split this into two pull requests so that you could run the coccinelle script yourself, however it's been plain sailing in linux-next so I've just included the whole lot here to keep things simple" * tag 'arm64-mmiowb' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (23 commits) docs/memory-barriers.txt: Update I/O section to be clearer about CPU vs thread docs/memory-barriers.txt: Fix style, spacing and grammar in I/O section arch: Remove dummy mmiowb() definitions from arch code net/ethernet/silan/sc92031: Remove stale comment about mmiowb() i40iw: Redefine i40iw_mmiowb() to do nothing scsi/qla1280: Remove stale comment about mmiowb() drivers: Remove explicit invocations of mmiowb() drivers: Remove useless trailing comments from mmiowb() invocations Documentation: Kill all references to mmiowb() riscv/mmiowb: Hook up mmwiob() implementation to asm-generic code powerpc/mmiowb: Hook up mmwiob() implementation to asm-generic code ia64/mmiowb: Add unconditional mmiowb() to arch_spin_unlock() mips/mmiowb: Add unconditional mmiowb() to arch_spin_unlock() sh/mmiowb: Add unconditional mmiowb() to arch_spin_unlock() m68k/io: Remove useless definition of mmiowb() nds32/io: Remove useless definition of mmiowb() x86/io: Remove useless definition of mmiowb() arm64/io: Remove useless definition of mmiowb() ARM/io: Remove useless definition of mmiowb() mmiowb: Hook up mmiowb helpers to spinlocks and generic I/O accessors ...
Diffstat (limited to 'arch/riscv/include')
-rw-r--r--arch/riscv/include/asm/io.h15
-rw-r--r--arch/riscv/include/asm/mmiowb.h14
2 files changed, 16 insertions, 13 deletions
diff --git a/arch/riscv/include/asm/io.h b/arch/riscv/include/asm/io.h
index 1d9c1376dc64..744fd92e77bc 100644
--- a/arch/riscv/include/asm/io.h
+++ b/arch/riscv/include/asm/io.h
@@ -20,6 +20,7 @@
#define _ASM_RISCV_IO_H
#include <linux/types.h>
+#include <asm/mmiowb.h>
extern void __iomem *ioremap(phys_addr_t offset, unsigned long size);
@@ -100,18 +101,6 @@ static inline u64 __raw_readq(const volatile void __iomem *addr)
#endif
/*
- * FIXME: I'm flip-flopping on whether or not we should keep this or enforce
- * the ordering with I/O on spinlocks like PowerPC does. The worry is that
- * drivers won't get this correct, but I also don't want to introduce a fence
- * into the lock code that otherwise only uses AMOs (and is essentially defined
- * by the ISA to be correct). For now I'm leaving this here: "o,w" is
- * sufficient to ensure that all writes to the device have completed before the
- * write to the spinlock is allowed to commit. I surmised this from reading
- * "ACQUIRES VS I/O ACCESSES" in memory-barriers.txt.
- */
-#define mmiowb() __asm__ __volatile__ ("fence o,w" : : : "memory");
-
-/*
* Unordered I/O memory access primitives. These are even more relaxed than
* the relaxed versions, as they don't even order accesses between successive
* operations to the I/O regions.
@@ -165,7 +154,7 @@ static inline u64 __raw_readq(const volatile void __iomem *addr)
#define __io_br() do {} while (0)
#define __io_ar(v) __asm__ __volatile__ ("fence i,r" : : : "memory");
#define __io_bw() __asm__ __volatile__ ("fence w,o" : : : "memory");
-#define __io_aw() do {} while (0)
+#define __io_aw() mmiowb_set_pending()
#define readb(c) ({ u8 __v; __io_br(); __v = readb_cpu(c); __io_ar(__v); __v; })
#define readw(c) ({ u16 __v; __io_br(); __v = readw_cpu(c); __io_ar(__v); __v; })
diff --git a/arch/riscv/include/asm/mmiowb.h b/arch/riscv/include/asm/mmiowb.h
new file mode 100644
index 000000000000..5d7e3a2b4e3b
--- /dev/null
+++ b/arch/riscv/include/asm/mmiowb.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _ASM_RISCV_MMIOWB_H
+#define _ASM_RISCV_MMIOWB_H
+
+/*
+ * "o,w" is sufficient to ensure that all writes to the device have completed
+ * before the write to the spinlock is allowed to commit.
+ */
+#define mmiowb() __asm__ __volatile__ ("fence o,w" : : : "memory");
+
+#include <asm-generic/mmiowb.h>
+
+#endif /* ASM_RISCV_MMIOWB_H */