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Subject[PATCH] MIPS: Introduce aligned IO memory operations
Date
Some platforms, such as Loongson64 or QEMU/KVM, don't support unaligned
instructions like lwl or lwr in IO memory access. However, our current
IO memcpy/memset is wired to the generic implementation, which leads
to a fatal result.

Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
---
arch/mips/Kconfig | 4 ++
arch/mips/include/asm/io.h | 10 ++++
arch/mips/kernel/Makefile | 2 +-
arch/mips/kernel/io.c | 98 ++++++++++++++++++++++++++++++++++++++
4 files changed, 113 insertions(+), 1 deletion(-)
create mode 100644 arch/mips/kernel/io.c

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 8b0cd692a43f..15a331aa23a2 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -1450,6 +1450,7 @@ config CPU_LOONGSON64
select CPU_SUPPORTS_HIGHMEM
select CPU_SUPPORTS_HUGEPAGES
select CPU_SUPPORTS_MSA
+ select CPU_NEEDS_ALIGNED_IO
select CPU_HAS_LOAD_STORE_LR
select CPU_DIEI_BROKEN if !LOONGSON3_ENHANCEMENT
select CPU_MIPSR2_IRQ_VI
@@ -2598,6 +2599,9 @@ config CPU_HAS_LOAD_STORE_LR
LWL, LWR, SWL, SWR (Load/store word left/right).
LDL, LDR, SDL, SDR (Load/store doubleword left/right, for 64bit systems).

+config CPU_NEEDS_ALIGNED_IO
+ bool
+
#
# Vectored interrupt mode is an R2 feature
#
diff --git a/arch/mips/include/asm/io.h b/arch/mips/include/asm/io.h
index 3f6ce74335b4..3b0eb4941f23 100644
--- a/arch/mips/include/asm/io.h
+++ b/arch/mips/include/asm/io.h
@@ -577,6 +577,15 @@ BUILDSTRING(l, u32)
BUILDSTRING(q, u64)
#endif

+#if defined(CONFIG_CPU_NEEDS_ALIGNED_IO)
+extern void __memcpy_fromio(void *, const volatile void __iomem *, size_t);
+extern void __memcpy_toio(volatile void __iomem *, const void *, size_t);
+extern void __memset_io(volatile void __iomem *, int, size_t);
+
+#define memset_io(c, v, l) __memset_io((c), (v), (l))
+#define memcpy_fromio(a, c, l) __memcpy_fromio((a), (c), (l))
+#define memcpy_toio(c, a, l) __memcpy_toio((c), (a), (l))
+#else
static inline void memset_io(volatile void __iomem *addr, unsigned char val, int count)
{
memset((void __force *) addr, val, count);
@@ -589,6 +598,7 @@ static inline void memcpy_toio(volatile void __iomem *dst, const void *src, int
{
memcpy((void __force *) dst, src, count);
}
+#endif

/*
* The caches on some architectures aren't dma-coherent and have need to
diff --git a/arch/mips/kernel/Makefile b/arch/mips/kernel/Makefile
index d6e97df51cfb..b07b97b9385e 100644
--- a/arch/mips/kernel/Makefile
+++ b/arch/mips/kernel/Makefile
@@ -8,7 +8,7 @@ extra-y := head.o vmlinux.lds
obj-y += cmpxchg.o cpu-probe.o branch.o elf.o entry.o genex.o idle.o irq.o \
process.o prom.o ptrace.o reset.o setup.o signal.o \
syscall.o time.o topology.o traps.o unaligned.o watch.o \
- vdso.o cacheinfo.o
+ vdso.o cacheinfo.o io.o

ifdef CONFIG_FUNCTION_TRACER
CFLAGS_REMOVE_ftrace.o = -pg
diff --git a/arch/mips/kernel/io.c b/arch/mips/kernel/io.c
new file mode 100644
index 000000000000..ca105aa76d4d
--- /dev/null
+++ b/arch/mips/kernel/io.c
@@ -0,0 +1,98 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <linux/export.h>
+#include <linux/types.h>
+#include <linux/io.h>
+
+#if defined(CONFIG_CPU_NEEDS_ALIGNED_IO)
+
+#if defined(CONFIG_64BIT)
+#define IO_LONG_READ __raw_readq
+#define IO_LONG_WRITE __raw_writeq
+#define IO_LONG_SIZE 8
+#else
+#define IO_LONG_READ __raw_readl
+#define IO_LONG_WRITE __raw_writel
+#define IO_LONG_SIZE 4
+#endif
+
+void __memcpy_fromio(void *to, const volatile void __iomem *from, size_t count)
+{
+ while (count && !IS_ALIGNED((unsigned long)from, IO_LONG_SIZE) &&
+ !IS_ALIGNED((unsigned long)to, IO_LONG_SIZE)) {
+ *(u8 *)to = __raw_readb(from);
+ from++;
+ to++;
+ count--;
+ }
+
+ while (count >= IO_LONG_SIZE) {
+ *(unsigned long *)to = IO_LONG_READ(from);
+ from += IO_LONG_SIZE;
+ to += IO_LONG_SIZE;
+ count -= IO_LONG_SIZE;
+ }
+
+ while (count) {
+ *(u8 *)to = __raw_readb(from);
+ from++;
+ to++;
+ count--;
+ }
+}
+EXPORT_SYMBOL(__memcpy_fromio);
+
+void __memcpy_toio(volatile void __iomem *to, const void *from, size_t count)
+{
+ while (count && !IS_ALIGNED((unsigned long)from, IO_LONG_SIZE) &&
+ !IS_ALIGNED((unsigned long)to, IO_LONG_SIZE)) {
+ __raw_writeb(*(u8 *)from, to);
+ from++;
+ to++;
+ count--;
+ }
+
+ while (count >= IO_LONG_SIZE) {
+ IO_LONG_WRITE(*(unsigned long *)from, to);
+ from += IO_LONG_SIZE;
+ to += IO_LONG_SIZE;
+ count -= IO_LONG_SIZE;
+ }
+
+ while (count) {
+ __raw_writeb(*(u8 *)from, to);
+ from++;
+ to++;
+ count--;
+ }
+}
+EXPORT_SYMBOL(__memcpy_toio);
+
+void __memset_io(volatile void __iomem *dst, int c, size_t count)
+{
+ unsigned long lc = (u8)c;
+ int i;
+
+ for (i = 1; i < IO_LONG_SIZE; i++)
+ lc |= (u8)c << (i * BITS_PER_BYTE);
+
+ while (count && !IS_ALIGNED((unsigned long)dst, IO_LONG_SIZE)) {
+ __raw_writeb((u8)c, dst);
+ dst++;
+ count--;
+ }
+
+ while (count >= IO_LONG_SIZE) {
+ IO_LONG_WRITE(lc, dst);
+ dst += IO_LONG_SIZE;
+ count -= IO_LONG_SIZE;
+ }
+
+ while (count) {
+ __raw_writeb(c, dst);
+ dst++;
+ count--;
+ }
+}
+EXPORT_SYMBOL(__memset_io);
+#endif
--
2.24.1
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