fs: Add pstore filesystem

pstore is a persistent storage filesystem used for RAMOOPS. It is used
to store console logs, panics, ftrace and other information in case of a
crash/panic/oops/reboot.

pstore is implemented for barebox as a read-only filesystem at the
moment. It may be extended later on. The idea is to provide a way to
extract essential data from the last running kernel.

Most of the code is copied from the kernel. However this is only a
lightweight implementation without real write support yet.

Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

9 files changed, 1468 insertions, 0 deletions

diff --git a/fs/Kconfig b/fs/Kconfig
index 9217bc81ea..5413a9295c 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -89,4 +89,6 @@ config FS_SMHFS
 	  located on a debugging host connected to the target running
 	  Barebox
 
+source fs/pstore/Kconfig
+
 endmenu
diff --git a/fs/Makefile b/fs/Makefile
index 46932057c1..2f952038d1 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -14,3 +14,4 @@ obj-$(CONFIG_FS_UIMAGEFS)	+= uimagefs.o
 obj-$(CONFIG_FS_EFI)	 += efi.o
 obj-$(CONFIG_FS_EFIVARFS) += efivarfs.o
 obj-$(CONFIG_FS_SMHFS) += smhfs.o
+obj-$(CONFIG_FS_PSTORE) += pstore/
diff --git a/fs/pstore/Kconfig b/fs/pstore/Kconfig
new file mode 100644
index 0000000000..0c6f136920
--- /dev/null
+++ b/fs/pstore/Kconfig
@@ -0,0 +1,86 @@
+menuconfig FS_PSTORE
+	bool
+	prompt "pstore fs support"
+	help
+	  Support for persistent storage to read data from the last crash, like
+	  panic, dmesg and ftrace.
+
+if FS_PSTORE
+
+config FS_PSTORE_RAMOOPS
+	bool
+	depends on RELOCATABLE
+	depends on ARM
+	select REED_SOLOMON
+	prompt "pstore RAM backend"
+	help
+	  Here the data is stored in a specific memory area that is neither
+	  overwritten by barebox nor the kernel.
+
+if FS_PSTORE_RAMOOPS
+
+config FS_PSTORE_RAMOOPS_RO
+	bool
+	default y
+	prompt "pstore RAM backend read only"
+	help
+	  This prevents the data from being erased by reinitializing the ramoops
+	  area with new empty ECCs. Select this if you want to see the same
+	  ramoops in the kernel.
+
+config FS_PSTORE_RAMOOPS_SIZE
+	int
+	prompt "Size of the RAMOOPS area"
+	default 2097152
+	help
+	  Size of the RAMOOPS area that is reserved. This is passed to the
+	  kernel as well as argument. Default is 2MiB.
+
+config FS_PSTORE_RAMOOPS_CONSOLE_SIZE
+	int
+	prompt "Size of the console area"
+	default 131072 # 2^17
+	range 4096 1073741824 # Random upper limitation of 1GiB
+	help
+	  Size of the RAMOOPS console area that is reserved. This is passed to
+	  the kernel as well as argument. It should be a power of 2.
+
+config FS_PSTORE_RAMOOPS_FTRACE_SIZE
+	int
+	prompt "Size of the ftrace area"
+	default 131072 # 2^17
+	range 4096 1073741824 # Random upper limitation of 1GiB
+	help
+	  Size of the RAMOOPS ftrace area that is reserved. This is passed to
+	  the kernel as well as argument. It should be a power of 2.
+
+config FS_PSTORE_RAMOOPS_PMSG_SIZE
+	int
+	prompt "Size of the userspace message area"
+	default 131072 # 2^17
+	range 4096 1073741824 # Random upper limitation of 1GiB
+	help
+	  Size of the RAMOOPS pmsg area that is reserved. This is passed to
+	  the kernel as well as argument. It should be a power of 2.
+
+config FS_PSTORE_RAMOOPS_RECORD_SIZE
+	int
+	prompt "Size of each oops area"
+	default 131072 # 2^17
+	range 4096 1073741824 # Random upper limitation of 1GiB
+	help
+	  Size of each RAMOOPS oops area. There are multiple oops/panic areas
+	  to store individual oops/panic messages. This is the size of each of
+	  these areas. It should be a power of 2.
+
+config FS_PSTORE_ECC_SIZE
+	int
+	prompt "ECC size"
+	default 16
+	help
+	  ECC size used. This is the amount of bytes for reed solomon codes
+	  that is used. 0 disables ECC.
+
+endif
+
+endif
diff --git a/fs/pstore/Makefile b/fs/pstore/Makefile
new file mode 100644
index 0000000000..c4043e1a8f
--- /dev/null
+++ b/fs/pstore/Makefile
@@ -0,0 +1,9 @@
+#
+# Makefile for the linux pstorefs routines.
+#
+
+obj-y				+= fs.o platform.o
+
+
+ramoops-objs			+= ram.o ram_core.o
+obj-$(CONFIG_FS_PSTORE_RAMOOPS)	+= ramoops.o
diff --git a/fs/pstore/fs.c b/fs/pstore/fs.c
new file mode 100644
index 0000000000..0e05d48ea0
--- /dev/null
+++ b/fs/pstore/fs.c
@@ -0,0 +1,280 @@
+/*
+ * Persistent Storage Barebox filesystem layer
+ * Copyright © 2015 Pengutronix, Markus Pargmann <mpa@pengutronix.de>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <common.h>
+#include <driver.h>
+#include <fs.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <fs.h>
+#include <malloc.h>
+#include <init.h>
+#include <linux/stat.h>
+#include <linux/err.h>
+#include <linux/pstore.h>
+#include <libbb.h>
+#include <rtc.h>
+#include <libfile.h>
+#include <linux/pstore.h>
+#include "internal.h"
+
+struct list_head allpstore = LIST_HEAD_INIT(allpstore);
+
+struct pstore_private {
+	char name[PSTORE_NAMELEN];
+	struct list_head list;
+	struct pstore_info *psi;
+	enum pstore_type_id type;
+	u64	id;
+	int	count;
+	ssize_t	size;
+	ssize_t pos;
+	char	data[];
+};
+
+/*
+ * Make a regular file in the root directory of our file system.
+ * Load it up with "size" bytes of data from "buf".
+ * Set the mtime & ctime to the date that this record was originally stored.
+ */
+int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id, int count,
+		  char *data, bool compressed, size_t size,
+		  struct pstore_info *psi)
+{
+	struct pstore_private	*private, *pos;
+
+	list_for_each_entry(pos, &allpstore, list) {
+		if (pos->type == type && pos->id == id && pos->psi == psi)
+			return -EEXIST;
+	}
+
+	private = xzalloc(sizeof(*private) + size);
+	if (!private)
+		return -ENOMEM;
+	private->type = type;
+	private->id = id;
+	private->count = count;
+	private->psi = psi;
+
+	switch (type) {
+	case PSTORE_TYPE_DMESG:
+		scnprintf(private->name, sizeof(private->name),
+			  "dmesg-%s-%lld%s", psname, id,
+			  compressed ? ".enc.z" : "");
+		break;
+	case PSTORE_TYPE_CONSOLE:
+		scnprintf(private->name, sizeof(private->name),
+			  "console-%s-%lld", psname, id);
+		break;
+	case PSTORE_TYPE_FTRACE:
+		scnprintf(private->name, sizeof(private->name),
+			  "ftrace-%s-%lld", psname, id);
+		break;
+	case PSTORE_TYPE_MCE:
+		scnprintf(private->name, sizeof(private->name),
+			  "mce-%s-%lld", psname, id);
+		break;
+	case PSTORE_TYPE_PPC_RTAS:
+		scnprintf(private->name, sizeof(private->name),
+			  "rtas-%s-%lld", psname, id);
+		break;
+	case PSTORE_TYPE_PPC_OF:
+		scnprintf(private->name, sizeof(private->name),
+			  "powerpc-ofw-%s-%lld", psname, id);
+		break;
+	case PSTORE_TYPE_PPC_COMMON:
+		scnprintf(private->name, sizeof(private->name),
+			  "powerpc-common-%s-%lld", psname, id);
+		break;
+	case PSTORE_TYPE_PMSG:
+		scnprintf(private->name, sizeof(private->name),
+			  "pmsg-%s-%lld", psname, id);
+		break;
+	case PSTORE_TYPE_UNKNOWN:
+		scnprintf(private->name, sizeof(private->name),
+			  "unknown-%s-%lld", psname, id);
+		break;
+	default:
+		scnprintf(private->name, sizeof(private->name),
+			  "type%d-%s-%lld", type, psname, id);
+		break;
+	}
+
+	memcpy(private->data, data, size);
+	private->size = size;
+
+	list_add(&private->list, &allpstore);
+
+	return 0;
+}
+
+static struct pstore_private *pstore_get_by_name(struct list_head *head,
+						 const char *name)
+{
+	struct pstore_private *d;
+
+	if (!name)
+		return NULL;
+
+	list_for_each_entry(d, head, list) {
+		if (strcmp(d->name, name) == 0)
+			return d;
+	}
+
+	return NULL;
+}
+
+static int pstore_open(struct device_d *dev, FILE *file, const char *filename)
+{
+	struct list_head *head = dev->priv;
+	struct pstore_private *d;
+
+	if (filename[0] == '/')
+		filename++;
+
+	d = pstore_get_by_name(head, filename);
+	if (!d)
+		return -EINVAL;
+
+	file->size = d->size;
+	file->priv = d;
+	d->pos = 0;
+
+	return 0;
+}
+
+static int pstore_close(struct device_d *dev, FILE *file)
+{
+	return 0;
+}
+
+static int pstore_read(struct device_d *dev, FILE *file, void *buf,
+		       size_t insize)
+{
+	struct pstore_private *d = file->priv;
+
+	memcpy(buf, &d->data[d->pos], insize);
+	d->pos += insize;
+
+	return insize;
+}
+
+static loff_t pstore_lseek(struct device_d *dev, FILE *file, loff_t pos)
+{
+	struct pstore_private *d = file->priv;
+
+	d->pos = pos;
+
+	return pos;
+}
+
+static DIR *pstore_opendir(struct device_d *dev, const char *pathname)
+{
+	DIR *dir;
+
+	dir = xzalloc(sizeof(DIR));
+
+	if (list_empty(&allpstore))
+		return dir;
+
+	dir->priv = list_first_entry(&allpstore, struct pstore_private, list);
+
+	return dir;
+}
+
+static struct dirent *pstore_readdir(struct device_d *dev, DIR *dir)
+{
+	struct pstore_private *d = dir->priv;
+
+	if (!d || &d->list == &allpstore)
+		return NULL;
+
+	strcpy(dir->d.d_name, d->name);
+	dir->priv = list_entry(d->list.next, struct pstore_private, list);
+
+	return &dir->d;
+}
+
+static int pstore_closedir(struct device_d *dev, DIR *dir)
+{
+	free(dir);
+
+	return 0;
+}
+
+static int pstore_stat(struct device_d *dev, const char *filename,
+		       struct stat *s)
+{
+	struct pstore_private *d;
+
+	if (filename[0] == '/')
+		filename++;
+
+	d = pstore_get_by_name(&allpstore, filename);
+	if (!d)
+		return -EINVAL;
+
+	s->st_size = d->size;
+	s->st_mode = S_IFREG | S_IRWXU | S_IRWXG | S_IRWXO;
+
+	return 0;
+}
+
+static void pstore_remove(struct device_d *dev)
+{
+	struct pstore_private *d, *tmp;
+
+	list_for_each_entry_safe(d, tmp, &allpstore, list) {
+		free(d);
+	}
+}
+
+static int pstore_probe(struct device_d *dev)
+{
+	struct list_head *priv = &allpstore;
+
+	dev->priv = priv;
+
+	dev_dbg(dev, "mounted pstore\n");
+
+	return 0;
+}
+
+static struct fs_driver_d pstore_driver = {
+	.open      = pstore_open,
+	.close     = pstore_close,
+	.read      = pstore_read,
+	.lseek     = pstore_lseek,
+	.opendir   = pstore_opendir,
+	.readdir   = pstore_readdir,
+	.closedir  = pstore_closedir,
+	.stat      = pstore_stat,
+	.flags     = FS_DRIVER_NO_DEV,
+	.type = filetype_uimage,
+	.drv = {
+		.probe  = pstore_probe,
+		.remove = pstore_remove,
+		.name = "pstore",
+	}
+};
+
+static int pstore_init(void)
+{
+	return register_fs_driver(&pstore_driver);
+}
+coredevice_initcall(pstore_init);
diff --git a/fs/pstore/internal.h b/fs/pstore/internal.h
new file mode 100644
index 0000000000..0a8df1f4e2
--- /dev/null
+++ b/fs/pstore/internal.h
@@ -0,0 +1,19 @@
+#ifndef __PSTORE_INTERNAL_H__
+#define __PSTORE_INTERNAL_H__
+
+#include <linux/types.h>
+#include <linux/time.h>
+#include <linux/pstore.h>
+
+#define PSTORE_NAMELEN  64
+
+extern struct pstore_info *psinfo;
+
+extern void	pstore_set_kmsg_bytes(int);
+extern void	pstore_get_records(int);
+extern int	pstore_mkfile(enum pstore_type_id, char *psname, u64 id,
+			      int count, char *data, bool compressed,
+			      size_t size, struct pstore_info *psi);
+extern int	pstore_is_mounted(void);
+
+#endif
diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
new file mode 100644
index 0000000000..dc2611f732
--- /dev/null
+++ b/fs/pstore/platform.c
@@ -0,0 +1,138 @@
+/*
+ * Persistent Storage - platform driver interface parts.
+ *
+ * Copyright (C) 2007-2008 Google, Inc.
+ * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2 as
+ *  published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#define pr_fmt(fmt) "pstore: " fmt
+
+#include <linux/types.h>
+#include <linux/pstore.h>
+#include <linux/string.h>
+#include <linux/kernel.h>
+#include <malloc.h>
+#include <printk.h>
+#include <module.h>
+
+#include "internal.h"
+
+struct pstore_info *psinfo;
+
+static char *backend;
+
+/* How much of the console log to snapshot */
+static unsigned long kmsg_bytes = 10240;
+
+void pstore_set_kmsg_bytes(int bytes)
+{
+	kmsg_bytes = bytes;
+}
+
+static int pstore_write_compat(enum pstore_type_id type,
+			       enum kmsg_dump_reason reason,
+			       u64 *id, unsigned int part, int count,
+			       bool compressed, size_t size,
+			       struct pstore_info *psi)
+{
+	return psi->write_buf(type, reason, id, part, psinfo->buf, compressed,
+			     size, psi);
+}
+
+/*
+ * platform specific persistent storage driver registers with
+ * us here. If pstore is already mounted, call the platform
+ * read function right away to populate the file system. If not
+ * then the pstore mount code will call us later to fill out
+ * the file system.
+ *
+ * Register with kmsg_dump to save last part of console log on panic.
+ */
+int pstore_register(struct pstore_info *psi)
+{
+	if (backend && strcmp(backend, psi->name))
+		return -EPERM;
+
+	spin_lock(&pstore_lock);
+	if (psinfo) {
+		spin_unlock(&pstore_lock);
+		return -EBUSY;
+	}
+
+	if (!psi->write)
+		psi->write = pstore_write_compat;
+	psinfo = psi;
+	mutex_init(&psinfo->read_mutex);
+	spin_unlock(&pstore_lock);
+
+	pstore_get_records(0);
+
+	pr_info("Registered %s as persistent store backend\n", psi->name);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(pstore_register);
+
+/*
+ * Read all the records from the persistent store. Create
+ * files in our filesystem.  Don't warn about -EEXIST errors
+ * when we are re-scanning the backing store looking to add new
+ * error records.
+ */
+void pstore_get_records(int quiet)
+{
+	struct pstore_info *psi = psinfo;
+	char			*buf = NULL;
+	ssize_t			size;
+	u64			id;
+	int			count;
+	enum pstore_type_id	type;
+	int			failed = 0, rc;
+	bool			compressed;
+	int			unzipped_len = -1;
+
+	if (!psi)
+		return;
+
+	mutex_lock(&psi->read_mutex);
+	if (psi->open && psi->open(psi))
+		goto out;
+
+	while ((size = psi->read(&id, &type, &count, &buf, &compressed,
+				psi)) > 0) {
+		if (compressed && (type == PSTORE_TYPE_DMESG)) {
+			pr_err("barebox does not have ramoops compression support\n");
+			continue;
+		}
+		rc = pstore_mkfile(type, psi->name, id, count, buf,
+				  compressed, (size_t)size, psi);
+		if (unzipped_len < 0) {
+			/* Free buffer other than big oops */
+			kfree(buf);
+			buf = NULL;
+		} else
+			unzipped_len = -1;
+		if (rc && (rc != -EEXIST || !quiet))
+			failed++;
+	}
+	if (psi->close)
+		psi->close(psi);
+out:
+	mutex_unlock(&psi->read_mutex);
+
+	if (failed)
+		pr_warn("failed to load %d record(s) from '%s'\n",
+			failed, psi->name);
+}
diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
new file mode 100644
index 0000000000..dc31ed16f9
--- /dev/null
+++ b/fs/pstore/ram.c
@@ -0,0 +1,507 @@
+/*
+ * RAM Oops/Panic logger
+ *
+ * Copyright (C) 2010 Marco Stornelli <marco.stornelli@gmail.com>
+ * Copyright (C) 2011 Kees Cook <keescook@chromium.org>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/err.h>
+#include <linux/pstore.h>
+#include <linux/time.h>
+#include <linux/ioport.h>
+#include <linux/compiler.h>
+#include <linux/pstore_ram.h>
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/log2.h>
+#include <malloc.h>
+#include <printk.h>
+#include <stdio.h>
+#include <globalvar.h>
+#include <init.h>
+#include <common.h>
+
+#define RAMOOPS_KERNMSG_HDR "===="
+#define MIN_MEM_SIZE 4096UL
+
+static const ulong record_size = CONFIG_FS_PSTORE_RAMOOPS_RECORD_SIZE;
+
+static const ulong ramoops_console_size = CONFIG_FS_PSTORE_RAMOOPS_CONSOLE_SIZE;
+
+static const ulong ramoops_ftrace_size = CONFIG_FS_PSTORE_RAMOOPS_FTRACE_SIZE;
+
+static const ulong ramoops_pmsg_size = CONFIG_FS_PSTORE_RAMOOPS_PMSG_SIZE;
+
+static const ulong mem_size = CONFIG_FS_PSTORE_RAMOOPS_SIZE;
+
+static const int dump_oops = 1;
+
+static const int ramoops_ecc = CONFIG_FS_PSTORE_ECC_SIZE;
+
+struct ramoops_context {
+	struct persistent_ram_zone **przs;
+	struct persistent_ram_zone *cprz;
+	struct persistent_ram_zone *fprz;
+	struct persistent_ram_zone *mprz;
+	phys_addr_t phys_addr;
+	unsigned long size;
+	unsigned int memtype;
+	size_t record_size;
+	size_t console_size;
+	size_t ftrace_size;
+	size_t pmsg_size;
+	int dump_oops;
+	struct persistent_ram_ecc_info ecc_info;
+	unsigned int max_dump_cnt;
+	unsigned int dump_write_cnt;
+	/* _read_cnt need clear on ramoops_pstore_open */
+	unsigned int dump_read_cnt;
+	unsigned int console_read_cnt;
+	unsigned int ftrace_read_cnt;
+	unsigned int pmsg_read_cnt;
+	struct pstore_info pstore;
+};
+
+static struct ramoops_platform_data *dummy_data;
+
+static int ramoops_pstore_open(struct pstore_info *psi)
+{
+	struct ramoops_context *cxt = psi->data;
+
+	cxt->dump_read_cnt = 0;
+	cxt->console_read_cnt = 0;
+	cxt->ftrace_read_cnt = 0;
+	cxt->pmsg_read_cnt = 0;
+	return 0;
+}
+
+static struct persistent_ram_zone *
+ramoops_get_next_prz(struct persistent_ram_zone *przs[], uint *c, uint max,
+		     u64 *id,
+		     enum pstore_type_id *typep, enum pstore_type_id type,
+		     bool update)
+{
+	struct persistent_ram_zone *prz;
+	int i = (*c)++;
+
+	if (i >= max)
+		return NULL;
+
+	prz = przs[i];
+	if (!prz)
+		return NULL;
+
+	/* Update old/shadowed buffer. */
+	if (update)
+		persistent_ram_save_old(prz);
+
+	if (!persistent_ram_old_size(prz))
+		return NULL;
+
+	*typep = type;
+	*id = i;
+
+	return prz;
+}
+
+static bool prz_ok(struct persistent_ram_zone *prz)
+{
+	return !!prz && !!(persistent_ram_old_size(prz) +
+			   persistent_ram_ecc_string(prz, NULL, 0));
+}
+
+static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type,
+				   int *count, char **buf, bool *compressed,
+				   struct pstore_info *psi)
+{
+	ssize_t size;
+	ssize_t ecc_notice_size;
+	struct ramoops_context *cxt = psi->data;
+	struct persistent_ram_zone *prz;
+
+	prz = ramoops_get_next_prz(cxt->przs, &cxt->dump_read_cnt,
+				   cxt->max_dump_cnt, id, type,
+				   PSTORE_TYPE_DMESG, 0);
+	if (!prz_ok(prz))
+		prz = ramoops_get_next_prz(&cxt->cprz, &cxt->console_read_cnt,
+					   1, id, type, PSTORE_TYPE_CONSOLE, 0);
+	if (!prz_ok(prz))
+		prz = ramoops_get_next_prz(&cxt->fprz, &cxt->ftrace_read_cnt,
+					   1, id, type, PSTORE_TYPE_FTRACE, 0);
+	if (!prz_ok(prz))
+		prz = ramoops_get_next_prz(&cxt->mprz, &cxt->pmsg_read_cnt,
+					   1, id, type, PSTORE_TYPE_PMSG, 0);
+	if (!prz_ok(prz))
+		return 0;
+
+	if (!persistent_ram_old(prz))
+		return 0;
+
+	size = persistent_ram_old_size(prz);
+
+	/* ECC correction notice */
+	ecc_notice_size = persistent_ram_ecc_string(prz, NULL, 0);
+
+	*buf = kmalloc(size + ecc_notice_size + 1, GFP_KERNEL);
+	if (*buf == NULL)
+		return -ENOMEM;
+
+	memcpy(*buf, (char *)persistent_ram_old(prz), size);
+	persistent_ram_ecc_string(prz, *buf + size, ecc_notice_size + 1);
+
+	return size + ecc_notice_size;
+}
+
+static int notrace ramoops_pstore_write_buf(enum pstore_type_id type,
+					    enum kmsg_dump_reason reason,
+					    u64 *id, unsigned int part,
+					    const char *buf,
+					    bool compressed, size_t size,
+					    struct pstore_info *psi)
+{
+	struct ramoops_context *cxt = psi->data;
+	struct persistent_ram_zone *prz;
+
+	if (type == PSTORE_TYPE_CONSOLE) {
+		if (!cxt->cprz)
+			return -ENOMEM;
+		persistent_ram_write(cxt->cprz, buf, size);
+		return 0;
+	} else if (type == PSTORE_TYPE_FTRACE) {
+		if (!cxt->fprz)
+			return -ENOMEM;
+		persistent_ram_write(cxt->fprz, buf, size);
+		return 0;
+	} else if (type == PSTORE_TYPE_PMSG) {
+		if (!cxt->mprz)
+			return -ENOMEM;
+		persistent_ram_write(cxt->mprz, buf, size);
+		return 0;
+	}
+
+	if (type != PSTORE_TYPE_DMESG)
+		return -EINVAL;
+
+	/* Explicitly only take the first part of any new crash.
+	 * If our buffer is larger than kmsg_bytes, this can never happen,
+	 * and if our buffer is smaller than kmsg_bytes, we don't want the
+	 * report split across multiple records.
+	 */
+	if (part != 1)
+		return -ENOSPC;
+
+	if (!cxt->przs)
+		return -ENOSPC;
+
+	prz = cxt->przs[cxt->dump_write_cnt];
+
+	persistent_ram_write(prz, buf, size);
+
+	cxt->dump_write_cnt = (cxt->dump_write_cnt + 1) % cxt->max_dump_cnt;
+
+	return 0;
+}
+
+static int ramoops_pstore_erase(enum pstore_type_id type, u64 id, int count,
+				struct pstore_info *psi)
+{
+	struct ramoops_context *cxt = psi->data;
+	struct persistent_ram_zone *prz;
+
+	switch (type) {
+	case PSTORE_TYPE_DMESG:
+		if (id >= cxt->max_dump_cnt)
+			return -EINVAL;
+		prz = cxt->przs[id];
+		break;
+	case PSTORE_TYPE_CONSOLE:
+		prz = cxt->cprz;
+		break;
+	case PSTORE_TYPE_FTRACE:
+		prz = cxt->fprz;
+		break;
+	case PSTORE_TYPE_PMSG:
+		prz = cxt->mprz;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	persistent_ram_free_old(prz);
+	persistent_ram_zap(prz);
+
+	return 0;
+}
+
+static struct ramoops_context oops_cxt = {
+	.pstore = {
+		.name	= "ramoops",
+		.open	= ramoops_pstore_open,
+		.read	= ramoops_pstore_read,
+		.write_buf	= ramoops_pstore_write_buf,
+		.erase	= ramoops_pstore_erase,
+	},
+};
+
+static void ramoops_free_przs(struct ramoops_context *cxt)
+{
+	int i;
+
+	cxt->max_dump_cnt = 0;
+	if (!cxt->przs)
+		return;
+
+	for (i = 0; !IS_ERR_OR_NULL(cxt->przs[i]); i++)
+		persistent_ram_free(cxt->przs[i]);
+	kfree(cxt->przs);
+}
+
+static int ramoops_init_przs(struct ramoops_context *cxt, phys_addr_t *paddr,
+			     size_t dump_mem_sz)
+{
+	int err = -ENOMEM;
+	int i;
+
+	if (!cxt->record_size)
+		return 0;
+
+	if (*paddr + dump_mem_sz - cxt->phys_addr > cxt->size) {
+		pr_err("no room for dumps\n");
+		return -ENOMEM;
+	}
+
+	cxt->max_dump_cnt = dump_mem_sz / cxt->record_size;
+	if (!cxt->max_dump_cnt)
+		return -ENOMEM;
+
+	cxt->przs = kzalloc(sizeof(*cxt->przs) * cxt->max_dump_cnt,
+			     GFP_KERNEL);
+	if (!cxt->przs) {
+		pr_err("failed to initialize a prz array for dumps\n");
+		goto fail_prz;
+	}
+
+	for (i = 0; i < cxt->max_dump_cnt; i++) {
+		size_t sz = cxt->record_size;
+
+		cxt->przs[i] = persistent_ram_new(*paddr, sz, 0,
+						  &cxt->ecc_info,
+						  cxt->memtype);
+		if (IS_ERR(cxt->przs[i])) {
+			err = PTR_ERR(cxt->przs[i]);
+			pr_err("failed to request mem region (0x%zx@0x%llx): %d\n",
+				sz, (unsigned long long)*paddr, err);
+			goto fail_prz;
+		}
+		*paddr += sz;
+	}
+
+	return 0;
+fail_prz:
+	ramoops_free_przs(cxt);
+	return err;
+}
+
+static int ramoops_init_prz(struct ramoops_context *cxt,
+			    struct persistent_ram_zone **prz,
+			    phys_addr_t *paddr, size_t sz, u32 sig)
+{
+	if (!sz)
+		return 0;
+
+	if (*paddr + sz - cxt->phys_addr > cxt->size) {
+		pr_err("no room for mem region (0x%zx@0x%llx) in (0x%lx@0x%llx)\n",
+			sz, (unsigned long long)*paddr,
+			cxt->size, (unsigned long long)cxt->phys_addr);
+		return -ENOMEM;
+	}
+
+	*prz = persistent_ram_new(*paddr, sz, sig, &cxt->ecc_info,
+				  cxt->memtype);
+	if (IS_ERR(*prz)) {
+		int err = PTR_ERR(*prz);
+
+		pr_err("failed to request mem region (0x%zx@0x%llx): %d\n",
+			sz, (unsigned long long)*paddr, err);
+		return err;
+	}
+
+	persistent_ram_zap(*prz);
+
+	*paddr += sz;
+
+	return 0;
+}
+
+static int ramoops_probe(struct ramoops_platform_data *pdata)
+{
+	struct ramoops_context *cxt = &oops_cxt;
+	size_t dump_mem_sz;
+	phys_addr_t paddr;
+	int err = -EINVAL;
+	char kernelargs[512];
+
+	/* Only a single ramoops area allowed at a time, so fail extra
+	 * probes.
+	 */
+	if (cxt->max_dump_cnt)
+		goto fail_out;
+
+	if (!pdata->mem_size || (!pdata->record_size && !pdata->console_size &&
+			!pdata->ftrace_size && !pdata->pmsg_size)) {
+		pr_err("The memory size and the record/console size must be "
+			"non-zero\n");
+		goto fail_out;
+	}
+
+	if (pdata->record_size && !is_power_of_2(pdata->record_size))
+		pdata->record_size = rounddown_pow_of_two(pdata->record_size);
+	if (pdata->console_size && !is_power_of_2(pdata->console_size))
+		pdata->console_size = rounddown_pow_of_two(pdata->console_size);
+	if (pdata->ftrace_size && !is_power_of_2(pdata->ftrace_size))
+		pdata->ftrace_size = rounddown_pow_of_two(pdata->ftrace_size);
+	if (pdata->pmsg_size && !is_power_of_2(pdata->pmsg_size))
+		pdata->pmsg_size = rounddown_pow_of_two(pdata->pmsg_size);
+
+	cxt->size = pdata->mem_size;
+	cxt->phys_addr = pdata->mem_address;
+	cxt->memtype = pdata->mem_type;
+	cxt->record_size = pdata->record_size;
+	cxt->console_size = pdata->console_size;
+	cxt->ftrace_size = pdata->ftrace_size;
+	cxt->pmsg_size = pdata->pmsg_size;
+	cxt->dump_oops = pdata->dump_oops;
+	cxt->ecc_info = pdata->ecc_info;
+
+	paddr = cxt->phys_addr;
+
+	dump_mem_sz = cxt->size - cxt->console_size - cxt->ftrace_size
+			- cxt->pmsg_size;
+	err = ramoops_init_przs(cxt, &paddr, dump_mem_sz);
+	if (err)
+		goto fail_out;
+
+	err = ramoops_init_prz(cxt, &cxt->cprz, &paddr,
+			       cxt->console_size, 0);
+	if (err)
+		goto fail_init_cprz;
+
+	err = ramoops_init_prz(cxt, &cxt->fprz, &paddr, cxt->ftrace_size, 0);
+	if (err)
+		goto fail_init_fprz;
+
+	err = ramoops_init_prz(cxt, &cxt->mprz, &paddr, cxt->pmsg_size, 0);
+	if (err)
+		goto fail_init_mprz;
+
+	cxt->pstore.data = cxt;
+	/*
+	 * Console can handle any buffer size, so prefer LOG_LINE_MAX. If we
+	 * have to handle dumps, we must have at least record_size buffer. And
+	 * for ftrace, bufsize is irrelevant (if bufsize is 0, buf will be
+	 * ZERO_SIZE_PTR).
+	 */
+	if (cxt->console_size)
+		cxt->pstore.bufsize = 1024; /* LOG_LINE_MAX */
+	cxt->pstore.bufsize = max(cxt->record_size, cxt->pstore.bufsize);
+	cxt->pstore.buf = kmalloc(cxt->pstore.bufsize, GFP_KERNEL);
+	spin_lock_init(&cxt->pstore.buf_lock);
+	if (!cxt->pstore.buf) {
+		pr_err("cannot allocate pstore buffer\n");
+		err = -ENOMEM;
+		goto fail_clear;
+	}
+
+	err = pstore_register(&cxt->pstore);
+	if (err) {
+		pr_err("registering with pstore failed\n");
+		goto fail_buf;
+	}
+
+	pr_info("attached 0x%lx@0x%llx, ecc: %d/%d\n",
+		cxt->size, (unsigned long long)cxt->phys_addr,
+		cxt->ecc_info.ecc_size, cxt->ecc_info.block_size);
+
+	scnprintf(kernelargs, sizeof(kernelargs),
+		  "ramoops.record_size=0x%x "
+		  "ramoops.console_size=0x%x "
+		  "ramoops.ftrace_size=0x%x "
+		  "ramoops.pmsg_size=0x%x "
+		  "ramoops.mem_address=0x%llx "
+		  "ramoops.mem_size=0x%lx "
+		  "ramoops.ecc=%d",
+		  cxt->record_size,
+		  cxt->console_size,
+		  cxt->ftrace_size,
+		  cxt->pmsg_size,
+		  (unsigned long long)cxt->phys_addr,
+		  mem_size,
+		  ramoops_ecc);
+	globalvar_add_simple("linux.bootargs.ramoops", kernelargs);
+
+	of_add_reserve_entry(cxt->phys_addr, cxt->phys_addr + mem_size);
+
+	return 0;
+
+fail_buf:
+	kfree(cxt->pstore.buf);
+fail_clear:
+	cxt->pstore.bufsize = 0;
+	kfree(cxt->mprz);
+fail_init_mprz:
+	kfree(cxt->fprz);
+fail_init_fprz:
+	kfree(cxt->cprz);
+fail_init_cprz:
+	ramoops_free_przs(cxt);
+fail_out:
+	return err;
+}
+unsigned long arm_mem_ramoops_get(void);
+
+static void ramoops_register_dummy(void)
+{
+	dummy_data = kzalloc(sizeof(*dummy_data), GFP_KERNEL);
+	if (!dummy_data) {
+		pr_info("could not allocate pdata\n");
+		return;
+	}
+
+	dummy_data->mem_size = mem_size;
+	dummy_data->mem_address = arm_mem_ramoops_get();
+	dummy_data->mem_type = 0;
+	dummy_data->record_size = record_size;
+	dummy_data->console_size = ramoops_console_size;
+	dummy_data->ftrace_size = ramoops_ftrace_size;
+	dummy_data->pmsg_size = ramoops_pmsg_size;
+	dummy_data->dump_oops = dump_oops;
+	/*
+	 * For backwards compatibility ramoops.ecc=1 means 16 bytes ECC
+	 * (using 1 byte for ECC isn't much of use anyway).
+	 */
+	dummy_data->ecc_info.ecc_size = ramoops_ecc == 1 ? 16 : ramoops_ecc;
+
+	ramoops_probe(dummy_data);
+}
+
+static int __init ramoops_init(void)
+{
+	ramoops_register_dummy();
+	return 0;
+}
+postcore_initcall(ramoops_init);
diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c
new file mode 100644
index 0000000000..d68d80900b
--- /dev/null
+++ b/fs/pstore/ram_core.c
@@ -0,0 +1,426 @@
+/*
+ * Copyright (C) 2012 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#define pr_fmt(fmt) "persistent_ram: " fmt
+
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/rslib.h>
+#include <linux/pstore_ram.h>
+#include <linux/string.h>
+#include <linux/rslib.h>
+#include <stdio.h>
+#include <malloc.h>
+#include <memory.h>
+#include <common.h>
+
+struct persistent_ram_buffer {
+	uint32_t sig;
+	resource_size_t start;
+	resource_size_t size;
+	uint8_t data[0];
+};
+
+#define PERSISTENT_RAM_SIG (0x43474244) /* DBGC */
+
+static inline size_t buffer_size(struct persistent_ram_zone *prz)
+{
+	return prz->buffer->size;
+}
+
+static inline size_t buffer_start(struct persistent_ram_zone *prz)
+{
+	return prz->buffer->start;
+}
+
+/* increase and wrap the start pointer, returning the old value */
+static size_t buffer_start_add(struct persistent_ram_zone *prz, size_t a)
+{
+	int old;
+	int new;
+
+	old = prz->buffer->start;
+	new = old + a;
+	while (unlikely(new >= prz->buffer_size))
+		new -= prz->buffer_size;
+	prz->buffer->start = new;
+
+	return old;
+}
+
+/* increase the size counter until it hits the max size */
+static void buffer_size_add(struct persistent_ram_zone *prz, size_t a)
+{
+	size_t old;
+	size_t new;
+
+	old = prz->buffer->size;
+	if (old == prz->buffer_size)
+		return;
+
+	new = old + a;
+	if (new > prz->buffer_size)
+		new = prz->buffer_size;
+	prz->buffer->size = new;
+}
+
+static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz,
+	uint8_t *data, size_t len, uint8_t *ecc)
+{
+	int i;
+	uint16_t par[prz->ecc_info.ecc_size];
+
+	/* Initialize the parity buffer */
+	memset(par, 0, sizeof(par));
+	encode_rs8(prz->rs_decoder, data, len, par, 0);
+	for (i = 0; i < prz->ecc_info.ecc_size; i++)
+		ecc[i] = par[i];
+}
+
+static int persistent_ram_decode_rs8(struct persistent_ram_zone *prz,
+	void *data, size_t len, uint8_t *ecc)
+{
+	int i;
+	uint16_t par[prz->ecc_info.ecc_size];
+
+	for (i = 0; i < prz->ecc_info.ecc_size; i++)
+		par[i] = ecc[i];
+	return decode_rs8(prz->rs_decoder, data, par, len,
+				NULL, 0, NULL, 0, NULL);
+}
+
+static void notrace persistent_ram_update_ecc(struct persistent_ram_zone *prz,
+	unsigned int start, unsigned int count)
+{
+	struct persistent_ram_buffer *buffer = prz->buffer;
+	uint8_t *buffer_end = buffer->data + prz->buffer_size;
+	uint8_t *block;
+	uint8_t *par;
+	int ecc_block_size = prz->ecc_info.block_size;
+	int ecc_size = prz->ecc_info.ecc_size;
+	int size = ecc_block_size;
+
+	if (!ecc_size)
+		return;
+
+	block = buffer->data + (start & ~(ecc_block_size - 1));
+	par = prz->par_buffer + (start / ecc_block_size) * ecc_size;
+
+	do {
+		if (block + ecc_block_size > buffer_end)
+			size = buffer_end - block;
+		persistent_ram_encode_rs8(prz, block, size, par);
+		block += ecc_block_size;
+		par += ecc_size;
+	} while (block < buffer->data + start + count);
+}
+
+static void persistent_ram_update_header_ecc(struct persistent_ram_zone *prz)
+{
+	struct persistent_ram_buffer *buffer = prz->buffer;
+
+	if (!prz->ecc_info.ecc_size)
+		return;
+
+	persistent_ram_encode_rs8(prz, (uint8_t *)buffer, sizeof(*buffer),
+				  prz->par_header);
+}
+
+static void persistent_ram_ecc_old(struct persistent_ram_zone *prz)
+{
+	struct persistent_ram_buffer *buffer = prz->buffer;
+	uint8_t *block;
+	uint8_t *par;
+
+	if (!prz->ecc_info.ecc_size)
+		return;
+
+	block = buffer->data;
+	par = prz->par_buffer;
+	while (block < buffer->data + buffer_size(prz)) {
+		int numerr;
+		int size = prz->ecc_info.block_size;
+		if (block + size > buffer->data + prz->buffer_size)
+			size = buffer->data + prz->buffer_size - block;
+		numerr = persistent_ram_decode_rs8(prz, block, size, par);
+		if (numerr > 0) {
+			pr_debug("error in block %p, %d\n", block, numerr);
+			prz->corrected_bytes += numerr;
+		} else if (numerr < 0) {
+			pr_debug("uncorrectable error in block %p\n", block);
+			prz->bad_blocks++;
+		}
+		block += prz->ecc_info.block_size;
+		par += prz->ecc_info.ecc_size;
+	}
+}
+
+static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
+				   struct persistent_ram_ecc_info *ecc_info)
+{
+	int numerr;
+	struct persistent_ram_buffer *buffer = prz->buffer;
+	int ecc_blocks;
+	size_t ecc_total;
+
+	if (!ecc_info || !ecc_info->ecc_size)
+		return 0;
+
+	prz->ecc_info.block_size = ecc_info->block_size ?: 128;
+	prz->ecc_info.ecc_size = ecc_info->ecc_size ?: 16;
+	prz->ecc_info.symsize = ecc_info->symsize ?: 8;
+	prz->ecc_info.poly = ecc_info->poly ?: 0x11d;
+
+	ecc_blocks = DIV_ROUND_UP(prz->buffer_size - prz->ecc_info.ecc_size,
+				  prz->ecc_info.block_size +
+				  prz->ecc_info.ecc_size);
+	ecc_total = (ecc_blocks + 1) * prz->ecc_info.ecc_size;
+	if (ecc_total >= prz->buffer_size) {
+		pr_err("%s: invalid ecc_size %u (total %zu, buffer size %zu)\n",
+		       __func__, prz->ecc_info.ecc_size,
+		       ecc_total, prz->buffer_size);
+		return -EINVAL;
+	}
+
+	prz->buffer_size -= ecc_total;
+	prz->par_buffer = buffer->data + prz->buffer_size;
+	prz->par_header = prz->par_buffer +
+			  ecc_blocks * prz->ecc_info.ecc_size;
+
+	/*
+	 * first consecutive root is 0
+	 * primitive element to generate roots = 1
+	 */
+	prz->rs_decoder = init_rs(prz->ecc_info.symsize, prz->ecc_info.poly,
+				  0, 1, prz->ecc_info.ecc_size);
+	if (prz->rs_decoder == NULL) {
+		pr_info("init_rs failed\n");
+		return -EINVAL;
+	}
+
+	prz->corrected_bytes = 0;
+	prz->bad_blocks = 0;
+
+	numerr = persistent_ram_decode_rs8(prz, buffer, sizeof(*buffer),
+					   prz->par_header);
+	if (numerr > 0) {
+		pr_info("error in header, %d\n", numerr);
+		prz->corrected_bytes += numerr;
+	} else if (numerr < 0) {
+		pr_info("uncorrectable error in header\n");
+		prz->bad_blocks++;
+	}
+
+	return 0;
+}
+
+ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
+	char *str, size_t len)
+{
+	ssize_t ret;
+
+	if (!prz->ecc_info.ecc_size)
+		return 0;
+
+	if (prz->corrected_bytes || prz->bad_blocks)
+		ret = snprintf(str, len, ""
+			"\n%d Corrected bytes, %d unrecoverable blocks\n",
+			prz->corrected_bytes, prz->bad_blocks);
+	else
+		ret = snprintf(str, len, "\nNo errors detected\n");
+
+	return ret;
+}
+
+static void notrace persistent_ram_update(struct persistent_ram_zone *prz,
+	const void *s, unsigned int start, unsigned int count)
+{
+	struct persistent_ram_buffer *buffer = prz->buffer;
+	memcpy(buffer->data + start, s, count);
+	persistent_ram_update_ecc(prz, start, count);
+}
+
+void persistent_ram_save_old(struct persistent_ram_zone *prz)
+{
+	struct persistent_ram_buffer *buffer = prz->buffer;
+	size_t size = buffer_size(prz);
+	size_t start = buffer_start(prz);
+
+	if (!size)
+		return;
+
+	if (!prz->old_log) {
+		persistent_ram_ecc_old(prz);
+		prz->old_log = kmalloc(size, GFP_KERNEL);
+	}
+	if (!prz->old_log) {
+		pr_err("failed to allocate buffer\n");
+		return;
+	}
+
+	prz->old_log_size = size;
+	memcpy(prz->old_log, &buffer->data[start], size - start);
+	memcpy(prz->old_log + size - start, &buffer->data[0], start);
+}
+
+int notrace persistent_ram_write(struct persistent_ram_zone *prz,
+	const void *s, unsigned int count)
+{
+	int rem;
+	int c = count;
+	size_t start;
+
+	if (unlikely(c > prz->buffer_size)) {
+		s += c - prz->buffer_size;
+		c = prz->buffer_size;
+	}
+
+	buffer_size_add(prz, c);
+
+	start = buffer_start_add(prz, c);
+
+	rem = prz->buffer_size - start;
+	if (unlikely(rem < c)) {
+		persistent_ram_update(prz, s, start, rem);
+		s += rem;
+		c -= rem;
+		start = 0;
+	}
+	persistent_ram_update(prz, s, start, c);
+
+	persistent_ram_update_header_ecc(prz);
+
+	return count;
+}
+
+size_t persistent_ram_old_size(struct persistent_ram_zone *prz)
+{
+	return prz->old_log_size;
+}
+
+void *persistent_ram_old(struct persistent_ram_zone *prz)
+{
+	return prz->old_log;
+}
+
+void persistent_ram_free_old(struct persistent_ram_zone *prz)
+{
+	kfree(prz->old_log);
+	prz->old_log = NULL;
+	prz->old_log_size = 0;
+}
+
+#ifdef CONFIG_FS_PSTORE_RAMOOPS_RO
+void persistent_ram_zap(struct persistent_ram_zone *prz)
+{
+}
+#else
+void persistent_ram_zap(struct persistent_ram_zone *prz)
+{
+	prz->buffer->start = 0;
+	prz->buffer->size = 0;
+	persistent_ram_update_header_ecc(prz);
+}
+#endif /* CONFIG_PSTORE_RAMOOPS_RO */
+
+static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size,
+		struct persistent_ram_zone *prz, int memtype)
+{
+	prz->res = request_sdram_region("persistent ram", start, size);
+	if (!prz->res)
+		return -ENOMEM;
+
+	prz->paddr = start;
+	prz->size = size;
+
+	prz->buffer = (void *)start;
+	prz->buffer_size = size - sizeof(struct persistent_ram_buffer);
+
+	return 0;
+}
+
+static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig,
+				    struct persistent_ram_ecc_info *ecc_info)
+{
+	int ret;
+
+	ret = persistent_ram_init_ecc(prz, ecc_info);
+	if (ret)
+		return ret;
+
+	sig ^= PERSISTENT_RAM_SIG;
+
+	if (prz->buffer->sig == sig) {
+		if (buffer_size(prz) > prz->buffer_size ||
+		    buffer_start(prz) > buffer_size(prz))
+			pr_info("found existing invalid buffer, size %zu, start %zu\n",
+				buffer_size(prz), buffer_start(prz));
+		else {
+			pr_debug("found existing buffer, size %zu, start %zu\n",
+				 buffer_size(prz), buffer_start(prz));
+			persistent_ram_save_old(prz);
+			return 0;
+		}
+	} else {
+		pr_debug("no valid data in buffer (sig = 0x%08x)\n",
+			 prz->buffer->sig);
+	}
+
+	prz->buffer->sig = sig;
+	persistent_ram_zap(prz);
+
+	return 0;
+}
+
+void persistent_ram_free(struct persistent_ram_zone *prz)
+{
+	if (!prz)
+		return;
+
+	if (prz->res) {
+		release_sdram_region(prz->res);
+		prz->res = NULL;
+	}
+
+	persistent_ram_free_old(prz);
+	kfree(prz);
+}
+
+struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
+			u32 sig, struct persistent_ram_ecc_info *ecc_info,
+			unsigned int memtype)
+{
+	struct persistent_ram_zone *prz;
+	int ret = -ENOMEM;
+
+	prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
+	if (!prz) {
+		pr_err("failed to allocate persistent ram zone\n");
+		goto err;
+	}
+
+	ret = persistent_ram_buffer_map(start, size, prz, memtype);
+	if (ret)
+		goto err;
+
+	ret = persistent_ram_post_init(prz, sig, ecc_info);
+	if (ret)
+		goto err;
+
+	return prz;
+err:
+	persistent_ram_free(prz);
+	return ERR_PTR(ret);
+}