powerpc/pseries: Read common partition via pstore

This patch exploits pstore subsystem to read details of common partition
in NVRAM to a separate file in /dev/pstore. For instance, common partition
details will be stored in a file named [common-nvram-6].
Signed-off-by: Aruna Balakrishnaiah <aruna@linux.vnet.ibm.com>
Reviewed-by: Jim Keniston <jkenisto@us.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/platforms/pseries/nvram.c

@@ -138,10 +138,17 @@ static struct nvram_os_partition of_config_partition = {
 	.os_partition = false
 };
 
+static struct nvram_os_partition common_partition = {
+	.name = "common",
+	.index = -1,
+	.os_partition = false
+};
+
 static enum pstore_type_id nvram_type_ids[] = {
 	PSTORE_TYPE_DMESG,
 	PSTORE_TYPE_PPC_RTAS,
 	PSTORE_TYPE_PPC_OF,
+	PSTORE_TYPE_PPC_COMMON,
 	-1
 };
 static int read_type;
@@ -530,7 +537,7 @@ static int nvram_pstore_write(enum pstore_type_id type,
 }
 
 /*
- * Reads the oops/panic report, rtas and of-config partition.
+ * Reads the oops/panic report, rtas, of-config and common partition.
  * Returns the length of the data we read from each partition.
  * Returns 0 if we've been called before.
  */
@@ -566,6 +573,14 @@ static ssize_t nvram_pstore_read(u64 *id, enum pstore_type_id *type,
 		time->tv_sec = 0;
 		time->tv_nsec = 0;
 		break;
+	case PSTORE_TYPE_PPC_COMMON:
+		sig = NVRAM_SIG_SYS;
+		part = &common_partition;
+		*type = PSTORE_TYPE_PPC_COMMON;
+		*id = PSTORE_TYPE_PPC_COMMON;
+		time->tv_sec = 0;
+		time->tv_nsec = 0;
+		break;
 	default:
 		return 0;
 	}

fs/pstore/inode.c

@@ -330,6 +330,9 @@ int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id, int count,
 	case PSTORE_TYPE_PPC_OF:
 		sprintf(name, "powerpc-ofw-%s-%lld", psname, id);
 		break;
+	case PSTORE_TYPE_PPC_COMMON:
+		sprintf(name, "powerpc-common-%s-%lld", psname, id);
+		break;
 	case PSTORE_TYPE_UNKNOWN:
 		sprintf(name, "unknown-%s-%lld", psname, id);
 		break;

include/linux/pstore.h

@@ -38,6 +38,7 @@ enum pstore_type_id {
 	/* PPC64 partition types */
 	PSTORE_TYPE_PPC_RTAS	= 4,
 	PSTORE_TYPE_PPC_OF	= 5,
+	PSTORE_TYPE_PPC_COMMON	= 6,
 	PSTORE_TYPE_UNKNOWN	= 255
 };