From 917afce1000d978dfd3f07da5da9d864bc49c77e Mon Sep 17 00:00:00 2001
From: Lennert Buytenhek <buytenh@wantstofly.org>
Date: Thu, 15 Sep 2005 13:00:25 +0100
Subject: [PATCH] [ARM] 2911/1: ixp2000_reg_{read,write} accessors
Patch from Lennert Buytenhek
This patch:
- changes the ixp2000_reg_write accessor to take a 'volatile void *'
instead of a 'volatile unsigned long *', which then allows passing in
a u32 * as first argument without being greeted with a warning; and
- adds an ixp2000_reg_read accessor.
We can then use these accessors in ixp2000 code to access on-chip
peripherals, instead of directly dereferencing pointers. This is for
use by the ixp2000 microengine driver which was recently announced on
netdev. We can't use readl/writel on the ixp2000 since it is usually
run in big-endian mode, and on big-endian platforms, readl/writel
perform byteswapping.
A future patch will remove the readback from ixp2000_reg_write, since
it's not needed to prevent erratum #66, and add manual readbacks to the
places that need them (writes are not synchronous since we map in device
space using XCB=101 nowadays), such as interrupt disabling and GPIO
manipulation. See also:
http://lists.arm.linux.org.uk/pipermail/linux-arm-kernel/2005-February/027084.html
Patch has been ACKed by Jeff Garzik.
Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---
include/asm-arm/arch-ixp2000/platform.h | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
diff --git a/include/asm-arm/arch-ixp2000/platform.h b/include/asm-arm/arch-ixp2000/platform.h
index c0caf3e3e6fd..6519498dbe25 100644
--- a/include/asm-arm/arch-ixp2000/platform.h
+++ b/include/asm-arm/arch-ixp2000/platform.h
@@ -31,20 +31,24 @@
#include <asm/system.h> /* Pickup local_irq_ functions */
-static inline void ixp2000_reg_write(volatile unsigned long *reg, unsigned long val)
+static inline void ixp2000_reg_write(volatile void *reg, unsigned long val)
{
- volatile unsigned long dummy;
+ unsigned long dummy;
unsigned long flags;
local_irq_save(flags);
- *reg = val;
+ *((volatile unsigned long *)reg) = val;
barrier();
- dummy = *reg;
+ dummy = *((volatile unsigned long *)reg);
local_irq_restore(flags);
}
#else
-#define ixp2000_reg_write(reg, val) (*reg = val)
+static inline void ixp2000_reg_write(volatile void *reg, unsigned long val)
+{
+ *((volatile unsigned long *)reg) = val;
+}
#endif /* IXDP2400 || IXDP2401 */
+#define ixp2000_reg_read(reg) (*((volatile unsigned long *)reg))
/*
* Boards may multiplex different devices on the 2nd channel of