v4.19.13 snapshot.
diff --git a/arch/powerpc/sysdev/mmio_nvram.c b/arch/powerpc/sysdev/mmio_nvram.c
new file mode 100644
index 0000000..c31f634
--- /dev/null
+++ b/arch/powerpc/sysdev/mmio_nvram.c
@@ -0,0 +1,158 @@
+/*
+ * memory mapped NVRAM
+ *
+ * (C) Copyright IBM Corp. 2005
+ *
+ * Authors : Utz Bacher <utz.bacher@de.ibm.com>
+ *
+ * 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, 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, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+
+#include <asm/machdep.h>
+#include <asm/nvram.h>
+#include <asm/prom.h>
+
+static void __iomem *mmio_nvram_start;
+static long mmio_nvram_len;
+static DEFINE_SPINLOCK(mmio_nvram_lock);
+
+static ssize_t mmio_nvram_read(char *buf, size_t count, loff_t *index)
+{
+ unsigned long flags;
+
+ if (*index >= mmio_nvram_len)
+ return 0;
+ if (*index + count > mmio_nvram_len)
+ count = mmio_nvram_len - *index;
+
+ spin_lock_irqsave(&mmio_nvram_lock, flags);
+
+ memcpy_fromio(buf, mmio_nvram_start + *index, count);
+
+ spin_unlock_irqrestore(&mmio_nvram_lock, flags);
+
+ *index += count;
+ return count;
+}
+
+static unsigned char mmio_nvram_read_val(int addr)
+{
+ unsigned long flags;
+ unsigned char val;
+
+ if (addr >= mmio_nvram_len)
+ return 0xff;
+
+ spin_lock_irqsave(&mmio_nvram_lock, flags);
+
+ val = ioread8(mmio_nvram_start + addr);
+
+ spin_unlock_irqrestore(&mmio_nvram_lock, flags);
+
+ return val;
+}
+
+static ssize_t mmio_nvram_write(char *buf, size_t count, loff_t *index)
+{
+ unsigned long flags;
+
+ if (*index >= mmio_nvram_len)
+ return 0;
+ if (*index + count > mmio_nvram_len)
+ count = mmio_nvram_len - *index;
+
+ spin_lock_irqsave(&mmio_nvram_lock, flags);
+
+ memcpy_toio(mmio_nvram_start + *index, buf, count);
+
+ spin_unlock_irqrestore(&mmio_nvram_lock, flags);
+
+ *index += count;
+ return count;
+}
+
+static void mmio_nvram_write_val(int addr, unsigned char val)
+{
+ unsigned long flags;
+
+ if (addr < mmio_nvram_len) {
+ spin_lock_irqsave(&mmio_nvram_lock, flags);
+
+ iowrite8(val, mmio_nvram_start + addr);
+
+ spin_unlock_irqrestore(&mmio_nvram_lock, flags);
+ }
+}
+
+static ssize_t mmio_nvram_get_size(void)
+{
+ return mmio_nvram_len;
+}
+
+int __init mmio_nvram_init(void)
+{
+ struct device_node *nvram_node;
+ unsigned long nvram_addr;
+ struct resource r;
+ int ret;
+
+ nvram_node = of_find_node_by_type(NULL, "nvram");
+ if (!nvram_node)
+ nvram_node = of_find_compatible_node(NULL, NULL, "nvram");
+ if (!nvram_node) {
+ printk(KERN_WARNING "nvram: no node found in device-tree\n");
+ return -ENODEV;
+ }
+
+ ret = of_address_to_resource(nvram_node, 0, &r);
+ if (ret) {
+ printk(KERN_WARNING "nvram: failed to get address (err %d)\n",
+ ret);
+ goto out;
+ }
+ nvram_addr = r.start;
+ mmio_nvram_len = resource_size(&r);
+ if ( (!mmio_nvram_len) || (!nvram_addr) ) {
+ printk(KERN_WARNING "nvram: address or length is 0\n");
+ ret = -EIO;
+ goto out;
+ }
+
+ mmio_nvram_start = ioremap(nvram_addr, mmio_nvram_len);
+ if (!mmio_nvram_start) {
+ printk(KERN_WARNING "nvram: failed to ioremap\n");
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ printk(KERN_INFO "mmio NVRAM, %luk at 0x%lx mapped to %p\n",
+ mmio_nvram_len >> 10, nvram_addr, mmio_nvram_start);
+
+ ppc_md.nvram_read_val = mmio_nvram_read_val;
+ ppc_md.nvram_write_val = mmio_nvram_write_val;
+ ppc_md.nvram_read = mmio_nvram_read;
+ ppc_md.nvram_write = mmio_nvram_write;
+ ppc_md.nvram_size = mmio_nvram_get_size;
+
+out:
+ of_node_put(nvram_node);
+ return ret;
+}