amd64_edac: Fix missing csrows sysfs nodes

While initializing the array of csrow attribute instances, a few csrows
were uninitialized. This happened because the module only performed a
check for DRAM base ctl register0's and not DRAM base ctl register1's
chip select enable bit. There could be systems with DIMMs populated
on only single memory channel whereas the module also assumed that a
dual channel dimm had double the memory size of a single memory channel
instead of checking the memory on each channel.

This patch fixes these above issues.

Signed-off-by: Ashish Shenoy <ashenoy@riverbed.com>
Signed-off-by: Prasanna S. Panchamukhi <ppanchamukhi@riverbed.com>
Link: http://lkml.kernel.org/r/4F459CFA.5090604@riverbed.com
Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>

drivers/edac/amd64_edac.c

@@ -2133,6 +2133,7 @@ static void read_mc_regs(struct amd64_pvt *pvt)
 static u32 amd64_csrow_nr_pages(struct amd64_pvt *pvt, u8 dct, int csrow_nr)
 {
 	u32 cs_mode, nr_pages;
+	u32 dbam = dct ? pvt->dbam1 : pvt->dbam0;
 
 	/*
 	 * The math on this doesn't look right on the surface because x/2*4 can
@@ -2141,16 +2142,10 @@ static u32 amd64_csrow_nr_pages(struct amd64_pvt *pvt, u8 dct, int csrow_nr)
 	 * number of bits to shift the DBAM register to extract the proper CSROW
 	 * field.
 	 */
-	cs_mode = (pvt->dbam0 >> ((csrow_nr / 2) * 4)) & 0xF;
+	cs_mode =  (dbam >> ((csrow_nr / 2) * 4)) & 0xF;
 
 	nr_pages = pvt->ops->dbam_to_cs(pvt, dct, cs_mode) << (20 - PAGE_SHIFT);
 
-	/*
-	 * If dual channel then double the memory size of single channel.
-	 * Channel count is 1 or 2
-	 */
-	nr_pages <<= (pvt->channel_count - 1);
-
 	debugf0("  (csrow=%d) DBAM map index= %d\n", csrow_nr, cs_mode);
 	debugf0("    nr_pages= %u  channel-count = %d\n",
 		nr_pages, pvt->channel_count);
@@ -2181,7 +2176,7 @@ static int init_csrows(struct mem_ctl_info *mci)
 	for_each_chip_select(i, 0, pvt) {
 		csrow = &mci->csrows[i];
 
-		if (!csrow_enabled(i, 0, pvt)) {
+		if (!csrow_enabled(i, 0, pvt) && !csrow_enabled(i, 1, pvt)) {
 			debugf1("----CSROW %d EMPTY for node %d\n", i,
 				pvt->mc_node_id);
 			continue;
@@ -2191,7 +2186,10 @@ static int init_csrows(struct mem_ctl_info *mci)
 			i, pvt->mc_node_id);
 
 		empty = 0;
-		csrow->nr_pages = amd64_csrow_nr_pages(pvt, 0, i);
+		if (csrow_enabled(i, 0, pvt))
+			csrow->nr_pages = amd64_csrow_nr_pages(pvt, 0, i);
+		if (csrow_enabled(i, 1, pvt))
+			csrow->nr_pages += amd64_csrow_nr_pages(pvt, 1, i);
 		find_csrow_limits(mci, i, &input_addr_min, &input_addr_max);
 		sys_addr = input_addr_to_sys_addr(mci, input_addr_min);
 		csrow->first_page = (u32) (sys_addr >> PAGE_SHIFT);