sb_edac: avoid INTERNAL ERROR message in EDAC with unspecified channel

commit 351fc4a9 upstream.

Intel IA32 SDM Table 15-14 defines channel 0xf as 'not specified', but
EDAC doesn't know about this and returns and INTERNAL ERROR when the
channel is greater than NUM_CHANNELS:

kernel: [ 1538.886456] CPU 0: Machine Check Exception: 0 Bank 1: 940000000000009f
kernel: [ 1538.886669] TSC 2bc68b22e7e812 ADDR 46dae7000 MISC 0 PROCESSOR 0:306e4 TIME 1390414572 SOCKET 0 APIC 0
kernel: [ 1538.971948] EDAC MC1: INTERNAL ERROR: channel value is out of range (15 >= 4)
kernel: [ 1538.972203] EDAC MC1: 0 CE memory read error on unknown memory (slot:0 page:0x46dae7 offset:0x0 grain:0 syndrome:0x0 -  area:DRAM err_code:0000:009f socket:1 channel_mask:1 rank:0)

This commit changes sb_edac to forward a channel of -1 to EDAC if the
channel is not specified.  edac_mc_handle_error() sets the channel to -1
internally after the error message anyway, so this commit should have no
effect other than avoiding the INTERNAL ERROR message when the channel
is not specified.
Signed-off-by: Seth Jennings <sjenning@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Cc: Vinson Lee <vlee@twopensource.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

drivers/edac/sb_edac.c

@@ -285,8 +285,9 @@ static const u32 correrrthrsld[] = {
  * sbridge structs
  */
 
-#define NUM_CHANNELS	4
-#define MAX_DIMMS	3		/* Max DIMMS per channel */
+#define NUM_CHANNELS		4
+#define MAX_DIMMS		3	/* Max DIMMS per channel */
+#define CHANNEL_UNSPECIFIED	0xf	/* Intel IA32 SDM 15-14 */
 
 enum type {
 	SANDY_BRIDGE,
@@ -1752,6 +1753,9 @@ static void sbridge_mce_output_error(struct mem_ctl_info *mci,
 
 	/* FIXME: need support for channel mask */
 
+	if (channel == CHANNEL_UNSPECIFIED)
+		channel = -1;
+
 	/* Call the helper to output message */
 	edac_mc_handle_error(tp_event, mci, core_err_cnt,
 			     m->addr >> PAGE_SHIFT, m->addr & ~PAGE_MASK, 0,