mmio_nvram.c

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/*
 * memory mapped NVRAM
 *
 * (C) Copyright IBM Corp. 2005
 *
 * Authors : Utz Bacher <[email protected]>
 *
 * 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\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;
}