drivers/edac: add new nmi rescan

Provides a way for NMI reported errors on x86 to notify the EDAC
subsystem pending ECC errors by writing to a software state variable.

Here's the reworked patch. I added an EDAC stub to the kernel so we can
have variables that are in the kernel even if EDAC is a module. I also
implemented the idea of using the chip driver to select error detection
mode via module parameter and eliminate the kernel compile option.
Please review/test. Thx!

Also, I only made changes to some of the chipset drivers since I am
unfamiliar with the other ones. We can add similar changes as we go.

Signed-off-by: Dave Jiang <djiang@mvista.com>
Signed-off-by: Douglas Thompson <dougthompson@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/edac/e752x_edac.c

@@ -22,6 +22,7 @@
 #include <linux/pci.h>
 #include <linux/pci_ids.h>
 #include <linux/slab.h>
+#include <linux/edac.h>
 #include "edac_mc.h"
 
 #define E752X_REVISION	" Ver: 2.0.1 " __DATE__
@@ -948,6 +949,16 @@ static int e752x_probe1(struct pci_dev *pdev, int dev_idx)
 	debugf0("%s(): mci\n", __func__);
 	debugf0("Starting Probe1\n");
 
+	/* make sure error reporting method is sane */
+	switch(edac_op_state) {
+		case EDAC_OPSTATE_POLL:
+		case EDAC_OPSTATE_NMI:
+			break;
+		default:
+			edac_op_state = EDAC_OPSTATE_POLL;
+			break;
+	}
+
 	/* check to see if device 0 function 1 is enabled; if it isn't, we
 	 * assume the BIOS has reserved it for a reason and is expecting
 	 * exclusive access, we take care not to violate that assumption and
@@ -1123,4 +1134,5 @@ MODULE_DESCRIPTION("MC support for Intel e752x memory controllers");
 module_param(force_function_unhide, int, 0444);
 MODULE_PARM_DESC(force_function_unhide, "if BIOS sets Dev0:Fun1 up as hidden:"
 " 1=force unhide and hope BIOS doesn't fight driver for Dev0:Fun1 access");
-
+module_param(edac_op_state, int, 0444);
+MODULE_PARM_DESC(edac_op_state, "EDAC Error Reporting state: 0=Poll,1=NMI");