nfit: scrub and register regions in a workqueue

Address range scrub is a potentially long running process that we want
to complete before any pmem regions are registered.  Perform this
operation asynchronously to allow other drivers to load in the meantime.

Platform firmware may have initiated a partial scrub prior to the driver
loading, so we must be careful to consume those results before kicking
off kernel initiated scrubs on other regions.

This rework also makes the registration path more tolerant of scrub
errors in that it splits scrubbing into 2 phases.  The first phase
synchronously waits for a platform-firmware initiated scrub to complete.
The second phase scans the remaining address ranges asynchronously and
notifies the related driver(s) when the scrub completes.
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/acpi/nfit.h

@@ -57,12 +57,16 @@ enum {
 	NFIT_ARS_START_BUSY = 6,
 	NFIT_ARS_CAP_NONE = 1,
 	NFIT_ARS_F_OVERFLOW = 1,
+	NFIT_ARS_TIMEOUT = 90,
 };
 
 struct nfit_spa {
 	struct acpi_nfit_system_address *spa;
 	struct list_head list;
-	int is_registered;
+	struct nd_region *nd_region;
+	unsigned int ars_done:1;
+	u32 clear_err_unit;
+	u32 max_ars;
 };
 
 struct nfit_dcr {
@@ -124,6 +128,8 @@ struct acpi_nfit_desc {
 	struct list_head idts;
 	struct nvdimm_bus *nvdimm_bus;
 	struct device *dev;
+	struct nd_cmd_ars_status *ars_status;
+	size_t ars_status_size;
 	struct work_struct work;
 	unsigned int cancel:1;
 	unsigned long dimm_dsm_force_en;