From: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxx> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx> --- drivers/acpi/nfit.c | 33 ++++++++++++++++++++++++++++++++- drivers/acpi/nfit.h | 5 +++++ 2 files changed, 37 insertions(+), 1 deletion(-) diff --git a/drivers/acpi/nfit.c b/drivers/acpi/nfit.c index 11aa513f2fda..628a42c41ab1 100644 --- a/drivers/acpi/nfit.c +++ b/drivers/acpi/nfit.c @@ -1059,7 +1059,9 @@ static void write_blk_ctl(struct nfit_blk *nfit_blk, unsigned int bw, 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 @@ static int nfit_blk_init_interleave(struct nfit_blk_mmio *mmio, 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 @@ static int acpi_nfit_blk_region_enable(struct nvdimm_bus *nvdimm_bus, 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, diff --git a/drivers/acpi/nfit.h b/drivers/acpi/nfit.h index 815cb561cdba..79b6d83875c1 100644 --- a/drivers/acpi/nfit.h +++ b/drivers/acpi/nfit.h @@ -40,6 +40,10 @@ enum nfit_uuids { NFIT_UUID_MAX, }; +enum { + ND_BLK_DCR_LATCH = 2, +}; + struct nfit_spa { struct acpi_nfit_system_address *spa; struct list_head list; @@ -131,6 +135,7 @@ struct nfit_blk { u64 stat_offset; u64 cmd_offset; void __iomem *nvdimm_flush; + u32 dimm_flags; }; enum spa_map_type { -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
