powerpc/powernv: Add pstore support on powernv

This patch extends pstore, a generic interface to platform dependent
persistent storage, support for powernv  platform to capture certain
useful information, during dying moments. Such support is already in
place for  pseries platform. This patch re-uses most of that code.

It is a common practice to compile kernels with both CONFIG_PPC_PSERIES=y
and CONFIG_PPC_POWERNV=y. The code in nvram_init_oops_partition() routine
still works as intended, as the caller is platform specific code which
passes the appropriate value for "rtas_partition_exists" parameter.
In all other places, where CONFIG_PPC_PSERIES or CONFIG_PPC_POWERNV
flag is used in this patchset, it is to reduce the kernel size in cases
where this flag is not set and doesn't have any impact logic wise.

Signed-off-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/nvram_64.c

@@ -127,6 +127,14 @@ static size_t oops_data_sz;
 static struct z_stream_s stream;
 
 #ifdef CONFIG_PSTORE
+#ifdef CONFIG_PPC_POWERNV
+static struct nvram_os_partition skiboot_partition = {
+	.name = "ibm,skiboot",
+	.index = -1,
+	.os_partition = false
+};
+#endif
+
 #ifdef CONFIG_PPC_PSERIES
 static struct nvram_os_partition of_config_partition = {
 	.name = "of-config",
@@ -476,6 +484,16 @@ static ssize_t nvram_pstore_read(u64 *id, enum pstore_type_id *type,
 		time->tv_sec = 0;
 		time->tv_nsec = 0;
 		break;
+#endif
+#ifdef CONFIG_PPC_POWERNV
+	case PSTORE_TYPE_PPC_OPAL:
+		sig = NVRAM_SIG_FW;
+		part = &skiboot_partition;
+		*type = PSTORE_TYPE_PPC_OPAL;
+		*id = PSTORE_TYPE_PPC_OPAL;
+		time->tv_sec = 0;
+		time->tv_nsec = 0;
+		break;
 #endif
 	default:
 		return 0;
@@ -552,8 +570,11 @@ static int nvram_pstore_init(void)
 {
 	int rc = 0;
 
-	nvram_type_ids[2] = PSTORE_TYPE_PPC_RTAS;
-	nvram_type_ids[3] = PSTORE_TYPE_PPC_OF;
+	if (machine_is(pseries)) {
+		nvram_type_ids[2] = PSTORE_TYPE_PPC_RTAS;
+		nvram_type_ids[3] = PSTORE_TYPE_PPC_OF;
+	} else
+		nvram_type_ids[2] = PSTORE_TYPE_PPC_OPAL;
 
 	nvram_pstore_info.buf = oops_data;
 	nvram_pstore_info.bufsize = oops_data_sz;

arch/powerpc/platforms/powernv/opal-nvram.c

@@ -16,6 +16,7 @@
 #include <linux/of.h>
 
 #include <asm/opal.h>
+#include <asm/nvram.h>
 #include <asm/machdep.h>
 
 static unsigned int nvram_size;
@@ -62,6 +63,15 @@ static ssize_t opal_nvram_write(char *buf, size_t count, loff_t *index)
 	return count;
 }
 
+static int __init opal_nvram_init_log_partitions(void)
+{
+	/* Scan nvram for partitions */
+	nvram_scan_partitions();
+	nvram_init_oops_partition(0);
+	return 0;
+}
+machine_arch_initcall(powernv, opal_nvram_init_log_partitions);
+
 void __init opal_nvram_init(void)
 {
 	struct device_node *np;