mtd: pxa3xx_nand: make the driver work on big-endian systems
authorThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Thu, 22 May 2014 12:56:52 +0000 (14:56 +0200)
committerBrian Norris <computersforpeace@gmail.com>
Wed, 28 May 2014 20:27:37 +0000 (13:27 -0700)
commitb7e460624f0f3c31150f3b09e75b0d009e22ba5f
tree947dc4817749334cd72ef634f77a1a705eb7b42d
parent2913aae5f9eae2f857cdeff5388bb22d0751aa08
mtd: pxa3xx_nand: make the driver work on big-endian systems

The pxa3xx_nand driver currently uses __raw_writel() and __raw_readl()
to access I/O registers. However, those functions do not do any
endianness swapping, which means that they won't work when the CPU
runs in big-endian but the I/O registers are little endian, which is
the common situation for ARM systems running big endian.

Since __raw_writel() and __raw_readl() do not include any memory
barriers and the pxa3xx_nand driver can only be compiled for ARM
platforms, the closest I/o accessors functions that do endianess
swapping are writel_relaxed() and readl_relaxed().

This patch has been verified to work on Armada XP GP: without the
patch, the NAND is not detected when the kernel runs big endian while
it is properly detected when the kernel runs little endian. With the
patch applied, the NAND is properly detected in both situations
(little and big endian).

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: <stable@vger.kernel.org> # v3.13+
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
drivers/mtd/nand/pxa3xx_nand.c