arch/powerpc/sysdev/mmio_nvram.c

   1 /*
   2  * memory mapped NVRAM
   3  *
   4  * (C) Copyright IBM Corp. 2005
   5  *
   6  * Authors : Utz Bacher <utz.bacher@de.ibm.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2, or (at your option)
  11  * any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  21  */
  22
  23 #include <linux/fs.h>
  24 #include <linux/init.h>
  25 #include <linux/kernel.h>
  26 #include <linux/spinlock.h>
  27 #include <linux/types.h>
  28
  29 #include <asm/machdep.h>
  30 #include <asm/nvram.h>
  31 #include <asm/prom.h>
  32
  33 static void __iomem *mmio_nvram_start;
  34 static long mmio_nvram_len;
  35 static DEFINE_SPINLOCK(mmio_nvram_lock);
  36
  37 static ssize_t mmio_nvram_read(char *buf, size_t count, loff_t *index)
  38 {
  39         unsigned long flags;
  40
  41         if (*index >= mmio_nvram_len)
  42                 return 0;
  43         if (*index + count > mmio_nvram_len)
  44                 count = mmio_nvram_len - *index;
  45
  46         spin_lock_irqsave(&mmio_nvram_lock, flags);
  47
  48         memcpy_fromio(buf, mmio_nvram_start + *index, count);
  49
  50         spin_unlock_irqrestore(&mmio_nvram_lock, flags);
  51
  52         *index += count;
  53         return count;
  54 }
  55
  56 static ssize_t mmio_nvram_write(char *buf, size_t count, loff_t *index)
  57 {
  58         unsigned long flags;
  59
  60         if (*index >= mmio_nvram_len)
  61                 return 0;
  62         if (*index + count > mmio_nvram_len)
  63                 count = mmio_nvram_len - *index;
  64
  65         spin_lock_irqsave(&mmio_nvram_lock, flags);
  66
  67         memcpy_toio(mmio_nvram_start + *index, buf, count);
  68
  69         spin_unlock_irqrestore(&mmio_nvram_lock, flags);
  70
  71         *index += count;
  72         return count;
  73 }
  74
  75 static ssize_t mmio_nvram_get_size(void)
  76 {
  77         return mmio_nvram_len;
  78 }
  79
  80 int __init mmio_nvram_init(void)
  81 {
  82         struct device_node *nvram_node;
  83         const unsigned long *buffer;
  84         int proplen;
  85         unsigned long nvram_addr;
  86         int ret;
  87
  88         ret = -ENODEV;
  89         nvram_node = of_find_node_by_type(NULL, "nvram");
  90         if (!nvram_node)
  91                 goto out;
  92
  93         ret = -EIO;
  94         buffer = get_property(nvram_node, "reg", &proplen);
  95         if (proplen != 2*sizeof(unsigned long))
  96                 goto out;
  97
  98         ret = -ENODEV;
  99         nvram_addr = buffer[0];
 100         mmio_nvram_len = buffer[1];
 101         if ( (!mmio_nvram_len) || (!nvram_addr) )
 102                 goto out;
 103
 104         mmio_nvram_start = ioremap(nvram_addr, mmio_nvram_len);
 105         if (!mmio_nvram_start)
 106                 goto out;
 107
 108         printk(KERN_INFO "mmio NVRAM, %luk mapped to %p\n",
 109                mmio_nvram_len >> 10, mmio_nvram_start);
 110
 111         ppc_md.nvram_read       = mmio_nvram_read;
 112         ppc_md.nvram_write      = mmio_nvram_write;
 113         ppc_md.nvram_size       = mmio_nvram_get_size;
 114
 115 out:
 116         of_node_put(nvram_node);
 117         return ret;
 118 }