nfit: add support for NVDIMM "latch" flag
Add support in the NFIT BLK I/O path for the "latch" flag
defined in the "Get Block NVDIMM Flags" _DSM function:
http://pmem.io/documents/NVDIMM_DSM_Interface_Example.pdf
This flag requires the driver to read back the command register after it
is written in the block I/O path. This ensures that the hardware has
fully processed the new command and moved the aperture appropriately.
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
diff --git a/drivers/acpi/nfit.c b/drivers/acpi/nfit.c
index 11aa513..628a42c 100644
--- a/drivers/acpi/nfit.c
+++ b/drivers/acpi/nfit.c
@@ -1059,7 +1059,9 @@
writeq(cmd, mmio->base + offset);
wmb_blk(nfit_blk);
- /* FIXME: conditionally perform read-back if mandated by firmware */
+
+ if (nfit_blk->dimm_flags & ND_BLK_DCR_LATCH)
+ readq(mmio->base + offset);
}
static int acpi_nfit_blk_single_io(struct nfit_blk *nfit_blk,
@@ -1266,6 +1268,28 @@
return 0;
}
+static int acpi_nfit_blk_get_flags(struct nvdimm_bus_descriptor *nd_desc,
+ struct nvdimm *nvdimm, struct nfit_blk *nfit_blk)
+{
+ struct nd_cmd_dimm_flags flags;
+ int rc;
+
+ memset(&flags, 0, sizeof(flags));
+ rc = nd_desc->ndctl(nd_desc, nvdimm, ND_CMD_DIMM_FLAGS, &flags,
+ sizeof(flags));
+
+ if (rc >= 0 && flags.status == 0)
+ nfit_blk->dimm_flags = flags.flags;
+ else if (rc == -ENOTTY) {
+ /* fall back to a conservative default */
+ nfit_blk->dimm_flags = ND_BLK_DCR_LATCH;
+ rc = 0;
+ } else
+ rc = -ENXIO;
+
+ return rc;
+}
+
static int acpi_nfit_blk_region_enable(struct nvdimm_bus *nvdimm_bus,
struct device *dev)
{
@@ -1340,6 +1364,13 @@
return rc;
}
+ rc = acpi_nfit_blk_get_flags(nd_desc, nvdimm, nfit_blk);
+ if (rc < 0) {
+ dev_dbg(dev, "%s: %s failed get DIMM flags\n",
+ __func__, nvdimm_name(nvdimm));
+ return rc;
+ }
+
nfit_flush = nfit_mem->nfit_flush;
if (nfit_flush && nfit_flush->flush->hint_count != 0) {
nfit_blk->nvdimm_flush = devm_ioremap_nocache(dev,