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Subject[PATCH v2] ARC: io.h: Implement reads{x}()/writes{x}()
Date
Some ARC CPU's do not support unaligned loads/stores. Currently, generic
implementation of reads{b/w/l}()/writes{b/w/l}() is being used with ARC.
This can lead to misfunction of some drivers as generic functions do a
plain dereference of a pointer that can be unaligned.

Let's use {get/put}_unaligned() helper instead of plain dereference of
pointer in order to fix this.

Changes from v1:
- Check if buffer is already aligned (David)
- Remove 64 bit mention (Alexey)

Signed-off-by: Jose Abreu <joabreu@synopsys.com>
Tested-by: Vitor Soares <soares@synopsys.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Joao Pinto <jpinto@synopsys.com>
Cc: Vitor Soares <soares@synopsys.com>
Cc: David Laight <David.Laight@ACULAB.COM>
---
arch/arc/include/asm/io.h | 61 +++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 61 insertions(+)

diff --git a/arch/arc/include/asm/io.h b/arch/arc/include/asm/io.h
index c22b181e8206..949759a45cff 100644
--- a/arch/arc/include/asm/io.h
+++ b/arch/arc/include/asm/io.h
@@ -12,6 +12,7 @@
#include <linux/types.h>
#include <asm/byteorder.h>
#include <asm/page.h>
+#include <asm/unaligned.h>

#ifdef CONFIG_ISA_ARCV2
#include <asm/barrier.h>
@@ -94,6 +95,34 @@ static inline u32 __raw_readl(const volatile void __iomem *addr)
return w;
}

+#define __raw_readsx(t,f) \
+static inline void __raw_reads##f(const volatile void __iomem *addr, \
+ void *buffer, unsigned int count) \
+{ \
+ if (count) { \
+ const unsigned long bptr = (unsigned long)buffer; \
+ u##t *buf = buffer; \
+\
+ do { \
+ u##t x = __raw_read##f(addr); \
+\
+ /* Some ARC CPU's don't support unaligned accesses */ \
+ if (bptr % ((t) / 8)) { \
+ put_unaligned(x, buf++); \
+ } else { \
+ *buf++ = x; \
+ } \
+ } while (--count); \
+ } \
+}
+
+#define __raw_readsb __raw_readsb
+__raw_readsx(8, b);
+#define __raw_readsw __raw_readsw
+__raw_readsx(16, w);
+#define __raw_readsl __raw_readsl
+__raw_readsx(32, l);
+
#define __raw_writeb __raw_writeb
static inline void __raw_writeb(u8 b, volatile void __iomem *addr)
{
@@ -126,6 +155,32 @@ static inline void __raw_writel(u32 w, volatile void __iomem *addr)

}

+#define __raw_writesx(t,f) \
+static inline void __raw_writes##f(volatile void __iomem *addr, \
+ const void *buffer, unsigned int count) \
+{ \
+ if (count) { \
+ const unsigned long bptr = (unsigned long)buffer; \
+ const u##t *buf = buffer; \
+\
+ do { \
+ /* Some ARC CPU's don't support unaligned accesses */ \
+ if (bptr % ((t) / 8)) { \
+ __raw_write##f(get_unaligned(buf++), addr); \
+ } else { \
+ __raw_write##f(*buf++, addr); \
+ } \
+ } while (--count); \
+ } \
+}
+
+#define __raw_writesb __raw_writesb
+__raw_writesx(8, b);
+#define __raw_writesw __raw_writesw
+__raw_writesx(16, w);
+#define __raw_writesl __raw_writesl
+__raw_writesx(32, l);
+
/*
* MMIO can also get buffered/optimized in micro-arch, so barriers needed
* Based on ARM model for the typical use case
@@ -141,10 +196,16 @@ static inline void __raw_writel(u32 w, volatile void __iomem *addr)
#define readb(c) ({ u8 __v = readb_relaxed(c); __iormb(); __v; })
#define readw(c) ({ u16 __v = readw_relaxed(c); __iormb(); __v; })
#define readl(c) ({ u32 __v = readl_relaxed(c); __iormb(); __v; })
+#define readsb(p,d,l) ({ __raw_readsb(p,d,l); __iormb(); })
+#define readsw(p,d,l) ({ __raw_readsw(p,d,l); __iormb(); })
+#define readsl(p,d,l) ({ __raw_readsl(p,d,l); __iormb(); })

#define writeb(v,c) ({ __iowmb(); writeb_relaxed(v,c); })
#define writew(v,c) ({ __iowmb(); writew_relaxed(v,c); })
#define writel(v,c) ({ __iowmb(); writel_relaxed(v,c); })
+#define writesb(p,d,l) ({ __iowmb(); __raw_writesb(p,d,l); })
+#define writesw(p,d,l) ({ __iowmb(); __raw_writesw(p,d,l); })
+#define writesl(p,d,l) ({ __iowmb(); __raw_writesl(p,d,l); })

/*
* Relaxed API for drivers which can handle barrier ordering themselves
--
2.7.4

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