/*

   * 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;
  }

  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
  ");
  		return -ENODEV;
  	}
  
  	ret = of_address_to_resource(nvram_node, 0, &r);
  	if (ret) {
  		printk(KERN_WARNING "nvram: failed to get address (err %d)
  ",
  		       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
  ");

  		ret = -EIO;

  		goto out;

  	}

  	mmio_nvram_start = ioremap(nvram_addr, mmio_nvram_len);

  	if (!mmio_nvram_start) {
  		printk(KERN_WARNING "nvram: failed to ioremap
  ");
  		ret = -ENOMEM;

  		goto out;

  	}

  	printk(KERN_INFO "mmio NVRAM, %luk at 0x%lx mapped to %p
  ",
  	       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;
  }