libnvdimm fix for 4.2

Hi Linus please pull from...

git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm libnvdimm-fixes

...to receive a single fix for the nd_blk driver.

The effect of getting the width of this register read wrong is that all I/O fails when the read returns non-zero. Given the availability of ACPI 6 NFIT enabled platforms, this could reasonably wait to come in during the 4.3 merge window with a tag for 4.2-stable. Otherwise, this makes the 4.2 kernel fully functional with devices that conform to the mmio-block-apertures defined in the ACPI 6 NFIT (NVDIMM Firmware Interface Table).

Full changelog and diffstat below.

---

The following changes since commit cbfe8fa6cd672011c755c3cd85c9ffd4e2d10a6f:

Linux 4.2-rc4 (2015-07-26 12:26:21 -0700)

are available in the git repository at:

git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm libnvdimm-fixes

for you to fetch changes up to de4a196c02a2a2631b516d90da6e8d052ccb07e8:

nfit, nd_blk: BLK status register is only 32 bits (2015-08-25 19:42:01 -0400)

----------------------------------------------------------------
Ross Zwisler (1):
nfit, nd_blk: BLK status register is only 32 bits

 drivers/acpi/nfit.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

---

commit de4a196c02a2a2631b516d90da6e8d052ccb07e8

Author: Ross Zwisler <[email protected]>
Date:   Thu Aug 20 16:27:38 2015 -0600

nfit, nd_blk: BLK status register is only 32 bits

Only read 32 bits for the BLK status register in read_blk_stat().

The format and size of this register is defined in the "NVDIMM Driver Writer's guide":

http://pmem.io/documents/NVDIMM_Driver_Writers_Guide.pdf

index 628a42c41ab1..bb29e56276bd 100644
@@ -1024,7 +1024,7 @@ static void wmb_blk(struct nfit_blk *nfit_blk)
 		wmb_pmem();
 }
 
-static u64 read_blk_stat(struct nfit_blk *nfit_blk, unsigned int bw)
+static u32 read_blk_stat(struct nfit_blk *nfit_blk, unsigned int bw)
 {
 	struct nfit_blk_mmio *mmio = &nfit_blk->mmio[DCR];
 	u64 offset = nfit_blk->stat_offset + mmio->size * bw;

@@ -1032,7 +1032,7 @@ static u64 read_blk_stat(struct nfit_blk *nfit_blk, unsigned int bw)
 	if (mmio->num_lines)
 		offset = to_interleave_offset(offset, mmio);
 
-	return readq(mmio->base + offset);
+	return readl(mmio->base + offset);
 }
 
 static void write_blk_ctl(struct nfit_blk *nfit_blk, unsigned int bw,