nfit, address-range-scrub: add module option to skip initial ars

After attempting to quickly retrieve known errors the kernel proceeds to
kick off a long running ARS. Add a module option to disable this
behavior at initialization time, or at new region discovery time.
Otherwise, ARS can be started manually regardless of the state of this
setting.

Co-developed-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/acpi/nfit/core.c

@@ -49,6 +49,10 @@ module_param(default_dsm_family, int, S_IRUGO);
 MODULE_PARM_DESC(default_dsm_family,
 		"Try this DSM type first when identifying NVDIMM family");
 
+static bool no_init_ars;
+module_param(no_init_ars, bool, 0644);
+MODULE_PARM_DESC(no_init_ars, "Skip ARS run at nfit init time");
+
 LIST_HEAD(acpi_descs);
 DEFINE_MUTEX(acpi_desc_lock);
 
@@ -2816,6 +2820,9 @@ static int ars_register(struct acpi_nfit_desc *acpi_desc, struct nfit_spa *nfit_
 {
 	int rc = *query_rc;
 
+	if (no_init_ars)
+		return acpi_nfit_register_region(acpi_desc, nfit_spa);
+
 	set_bit(ARS_REQ, &nfit_spa->ars_state);
 	set_bit(ARS_SHORT, &nfit_spa->ars_state);