amd64_edac: Rewrite unganged mode code of f10_early_channel_count

Simplify the procedure by checking if there is any DIMM in each channel.
This patch will fix the bugs such as when there is no DIMMs under
certain node, two DIMMs in the same channel, and only one DIMM in each
channel of the node.

Borislav: minor fixups
Signed-off-by: Wan Wei <wanwei@mail.dawning.com.cn>
Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>

drivers/edac/amd64_edac.c

@@ -1255,7 +1255,9 @@ static int k8_dbam_map_to_pages(struct amd64_pvt *pvt, int dram_map)
  */
 static int f10_early_channel_count(struct amd64_pvt *pvt)
 {
+	int dbams[] = { DBAM0, DBAM1 };
 	int err = 0, channels = 0;
+	int i, j;
 	u32 dbam;
 
 	err = pci_read_config_dword(pvt->dram_f2_ctl, F10_DCLR_0, &pvt->dclr0);
@@ -1288,45 +1290,18 @@ static int f10_early_channel_count(struct amd64_pvt *pvt)
 	 * is more than just one DIMM present in unganged mode. Need to check
 	 * both controllers since DIMMs can be placed in either one.
 	 */
-	channels = 0;
-	err = pci_read_config_dword(pvt->dram_f2_ctl, DBAM0, &dbam);
+	for (i = 0; i < ARRAY_SIZE(dbams); i++) {
+		err = pci_read_config_dword(pvt->dram_f2_ctl, dbams[i], &dbam);
 		if (err)
 			goto err_reg;
 
-	if (DBAM_DIMM(0, dbam) > 0)
+		for (j = 0; j < 4; j++) {
+			if (DBAM_DIMM(j, dbam) > 0) {
 				channels++;
-	if (DBAM_DIMM(1, dbam) > 0)
-		channels++;
-	if (DBAM_DIMM(2, dbam) > 0)
-		channels++;
-	if (DBAM_DIMM(3, dbam) > 0)
-		channels++;
-
-	/* If more than 2 DIMMs are present, then we have 2 channels */
-	if (channels > 2)
-		channels = 2;
-	else if (channels == 0) {
-		/* No DIMMs on DCT0, so look at DCT1 */
-		err = pci_read_config_dword(pvt->dram_f2_ctl, DBAM1, &dbam);
-		if (err)
-			goto err_reg;
-
-		if (DBAM_DIMM(0, dbam) > 0)
-			channels++;
-		if (DBAM_DIMM(1, dbam) > 0)
-			channels++;
-		if (DBAM_DIMM(2, dbam) > 0)
-			channels++;
-		if (DBAM_DIMM(3, dbam) > 0)
-			channels++;
-
-		if (channels > 2)
-			channels = 2;
+				break;
+			}
+		}
 	}
-
-	/* If we found ALL 0 values, then assume just ONE DIMM-ONE Channel */
-	if (channels == 0)
-		channels = 1;
 
 	debugf0("MCT channel count: %d\n", channels);