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 unsigned char mmio_nvram_read_val(int addr)
  57 {
  58         unsigned long flags;
  59         unsigned char val;
  60
  61         if (addr >= mmio_nvram_len)
  62                 return 0xff;
  63
  64         spin_lock_irqsave(&mmio_nvram_lock, flags);
  65
  66         val = ioread8(mmio_nvram_start + addr);
  67
  68         spin_unlock_irqrestore(&mmio_nvram_lock, flags);
  69
  70         return val;
  71 }
  72
  73 static ssize_t mmio_nvram_write(char *buf, size_t count, loff_t *index)
  74 {
  75         unsigned long flags;
  76
  77         if (*index >= mmio_nvram_len)
  78                 return 0;
  79         if (*index + count > mmio_nvram_len)
  80                 count = mmio_nvram_len - *index;
  81
  82         spin_lock_irqsave(&mmio_nvram_lock, flags);
  83
  84         memcpy_toio(mmio_nvram_start + *index, buf, count);
  85
  86         spin_unlock_irqrestore(&mmio_nvram_lock, flags);
  87
  88         *index += count;
  89         return count;
  90 }
  91
  92 static void mmio_nvram_write_val(int addr, unsigned char val)
  93 {
  94         unsigned long flags;
  95
  96         if (addr < mmio_nvram_len) {
  97                 spin_lock_irqsave(&mmio_nvram_lock, flags);
  98
  99                 iowrite8(val, mmio_nvram_start + addr);
 100
 101                 spin_unlock_irqrestore(&mmio_nvram_lock, flags);
 102         }
 103 }
 104
 105 static ssize_t mmio_nvram_get_size(void)
 106 {
 107         return mmio_nvram_len;
 108 }
 109
 110 int __init mmio_nvram_init(void)
 111 {
 112         struct device_node *nvram_node;
 113         unsigned long nvram_addr;
 114         struct resource r;
 115         int ret;
 116
 117         nvram_node = of_find_node_by_type(NULL, "nvram");
 118         if (!nvram_node)
 119                 nvram_node = of_find_compatible_node(NULL, NULL, "nvram");
 120         if (!nvram_node) {
 121                 printk(KERN_WARNING "nvram: no node found in device-tree\n");
 122                 return -ENODEV;
 123         }
 124
 125         ret = of_address_to_resource(nvram_node, 0, &r);
 126         if (ret) {
 127                 printk(KERN_WARNING "nvram: failed to get address (err %d)\n",
 128                        ret);
 129                 goto out;
 130         }
 131         nvram_addr = r.start;
 132         mmio_nvram_len = resource_size(&r);
 133         if ( (!mmio_nvram_len) || (!nvram_addr) ) {
 134                 printk(KERN_WARNING "nvram: address or length is 0\n");
 135                 ret = -EIO;
 136                 goto out;
 137         }
 138
 139         mmio_nvram_start = ioremap(nvram_addr, mmio_nvram_len);
 140         if (!mmio_nvram_start) {
 141                 printk(KERN_WARNING "nvram: failed to ioremap\n");
 142                 ret = -ENOMEM;
 143                 goto out;
 144         }
 145
 146         printk(KERN_INFO "mmio NVRAM, %luk at 0x%lx mapped to %p\n",
 147                mmio_nvram_len >> 10, nvram_addr, mmio_nvram_start);
 148
 149         ppc_md.nvram_read_val   = mmio_nvram_read_val;
 150         ppc_md.nvram_write_val  = mmio_nvram_write_val;
 151         ppc_md.nvram_read       = mmio_nvram_read;
 152         ppc_md.nvram_write      = mmio_nvram_write;
 153         ppc_md.nvram_size       = mmio_nvram_get_size;
 154
 155 out:
 156         of_node_put(nvram_node);
 157         return ret;
 158 }