nvram.c

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/*
 *  c 2001 PPC 64 Team, IBM Corp
 *
 *      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 of the License, or (at your option) any later version.
 *
 * /dev/nvram driver for PPC
 *
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <asm/uaccess.h>
#include <asm/prom.h>
#include <asm/machdep.h>
#include <asm/rtas.h>
#include "chrp.h"

static unsigned int nvram_size;
static unsigned char nvram_buf[4];
static DEFINE_SPINLOCK(nvram_lock);

static unsigned char chrp_nvram_read(int addr)
{
    unsigned int done;
    unsigned long flags;
    unsigned char ret;

    if (addr >= nvram_size) {
        printk(KERN_DEBUG "%s: read addr %d > nvram_size %u\n",
               current->comm, addr, nvram_size);
        return 0xff;
    }
    spin_lock_irqsave(&nvram_lock, flags);
    if ((rtas_call(rtas_token("nvram-fetch"), 3, 2, &done, addr,
               __pa(nvram_buf), 1) != 0) || 1 != done)
        ret = 0xff;
    else
        ret = nvram_buf[0];
    spin_unlock_irqrestore(&nvram_lock, flags);

    return ret;
}

static void chrp_nvram_write(int addr, unsigned char val)
{
    unsigned int done;
    unsigned long flags;

    if (addr >= nvram_size) {
        printk(KERN_DEBUG "%s: write addr %d > nvram_size %u\n",
               current->comm, addr, nvram_size);
        return;
    }
    spin_lock_irqsave(&nvram_lock, flags);
    nvram_buf[0] = val;
    if ((rtas_call(rtas_token("nvram-store"), 3, 2, &done, addr,
               __pa(nvram_buf), 1) != 0) || 1 != done)
        printk(KERN_DEBUG "rtas IO error storing 0x%02x at %d", val, addr);
    spin_unlock_irqrestore(&nvram_lock, flags);
}

void __init chrp_nvram_init(void)
{
    struct device_node *nvram;
    const unsigned int *nbytes_p;
    unsigned int proplen;

    nvram = of_find_node_by_type(NULL, "nvram");
    if (nvram == NULL)
        return;

    nbytes_p = of_get_property(nvram, "#bytes", &proplen);
    if (nbytes_p == NULL || proplen != sizeof(unsigned int)) {
        of_node_put(nvram);
        return;
    }

    nvram_size = *nbytes_p;

    printk(KERN_INFO "CHRP nvram contains %u bytes\n", nvram_size);
    of_node_put(nvram);

    ppc_md.nvram_read_val = chrp_nvram_read;
    ppc_md.nvram_write_val = chrp_nvram_write;

    return;
}