powerpc/pseries: Read of-config partition via pstore

This patch set exploits the pstore subsystem to read details of
of-config partition in NVRAM to a separate file in /dev/pstore.
For instance, of-config partition details will be stored in a
file named [of-nvram-5].
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

@@ -132,9 +132,16 @@ static size_t oops_data_sz;
 static struct z_stream_s stream;
 
 #ifdef CONFIG_PSTORE
+static struct nvram_os_partition of_config_partition = {
+	.name = "of-config",
+	.index = -1,
+	.os_partition = false
+};
+
 static enum pstore_type_id nvram_type_ids[] = {
 	PSTORE_TYPE_DMESG,
 	PSTORE_TYPE_PPC_RTAS,
+	PSTORE_TYPE_PPC_OF,
 	-1
 };
 static int read_type;
@@ -332,11 +339,16 @@ int nvram_read_partition(struct nvram_os_partition *part, char *buff,
 
 	tmp_index = part->index;
 
-	rc = ppc_md.nvram_read((char *)&info, sizeof(struct err_log_info), &tmp_index);
+	if (part->os_partition) {
+		rc = ppc_md.nvram_read((char *)&info,
+					sizeof(struct err_log_info),
+					&tmp_index);
 		if (rc <= 0) {
-		pr_err("%s: Failed nvram_read (%d)\n", __FUNCTION__, rc);
+			pr_err("%s: Failed nvram_read (%d)\n", __FUNCTION__,
+									rc);
 			return rc;
 		}
+	}
 
 	rc = ppc_md.nvram_read(buff, length, &tmp_index);
 	if (rc <= 0) {
@@ -344,8 +356,10 @@ int nvram_read_partition(struct nvram_os_partition *part, char *buff,
 		return rc;
 	}
 
+	if (part->os_partition) {
 		*error_log_cnt = info.seq_num;
 		*err_type = info.error_type;
+	}
 
 	return 0;
 }
@@ -516,7 +530,7 @@ static int nvram_pstore_write(enum pstore_type_id type,
 }
 
 /*
- * Reads the oops/panic report and ibm,rtas-log partition.
+ * Reads the oops/panic report, rtas and of-config partition.
  * Returns the length of the data we read from each partition.
  * Returns 0 if we've been called before.
  */
@@ -525,9 +539,11 @@ static ssize_t nvram_pstore_read(u64 *id, enum pstore_type_id *type,
 				struct pstore_info *psi)
 {
 	struct oops_log_info *oops_hdr;
-	unsigned int err_type, id_no;
+	unsigned int err_type, id_no, size = 0;
 	struct nvram_os_partition *part = NULL;
 	char *buff = NULL;
+	int sig = 0;
+	loff_t p;
 
 	read_type++;
 
@@ -542,10 +558,29 @@ static ssize_t nvram_pstore_read(u64 *id, enum pstore_type_id *type,
 		time->tv_sec = last_rtas_event;
 		time->tv_nsec = 0;
 		break;
+	case PSTORE_TYPE_PPC_OF:
+		sig = NVRAM_SIG_OF;
+		part = &of_config_partition;
+		*type = PSTORE_TYPE_PPC_OF;
+		*id = PSTORE_TYPE_PPC_OF;
+		time->tv_sec = 0;
+		time->tv_nsec = 0;
+		break;
 	default:
 		return 0;
 	}
 
+	if (!part->os_partition) {
+		p = nvram_find_partition(part->name, sig, &size);
+		if (p <= 0) {
+			pr_err("nvram: Failed to find partition %s, "
+				"err %d\n", part->name, (int)p);
+			return 0;
+		}
+		part->index = p;
+		part->size = size;
+	}
+
 	buff = kmalloc(part->size, GFP_KERNEL);
 
 	if (!buff)
@@ -557,6 +592,8 @@ static ssize_t nvram_pstore_read(u64 *id, enum pstore_type_id *type,
 	}
 
 	*count = 0;
+
+	if (part->os_partition)
 		*id = id_no;
 
 	if (nvram_type_ids[read_type] == PSTORE_TYPE_DMESG) {

fs/pstore/inode.c

@@ -327,6 +327,9 @@ int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id, int count,
 	case PSTORE_TYPE_PPC_RTAS:
 		sprintf(name, "rtas-%s-%lld", psname, id);
 		break;
+	case PSTORE_TYPE_PPC_OF:
+		sprintf(name, "powerpc-ofw-%s-%lld", psname, id);
+		break;
 	case PSTORE_TYPE_UNKNOWN:
 		sprintf(name, "unknown-%s-%lld", psname, id);
 		break;

include/linux/pstore.h

@@ -37,6 +37,7 @@ enum pstore_type_id {
 	PSTORE_TYPE_FTRACE	= 3,
 	/* PPC64 partition types */
 	PSTORE_TYPE_PPC_RTAS	= 4,
+	PSTORE_TYPE_PPC_OF	= 5,
 	PSTORE_TYPE_UNKNOWN	= 255
 };