opal-nvram.c

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/*
 * PowerNV nvram code.
 *
 * Copyright 2011 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.
 */

#define DEBUG

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/of.h>

#include <asm/opal.h>
#include <asm/machdep.h>

static unsigned int nvram_size;

static ssize_t opal_nvram_size(void)
{
    return nvram_size;
}

static ssize_t opal_nvram_read(char *buf, size_t count, loff_t *index)
{
    s64 rc;
    int off;

    if (*index >= nvram_size)
        return 0;
    off = *index;
    if ((off + count) > nvram_size)
        count = nvram_size - off;
    rc = opal_read_nvram(__pa(buf), count, off);
    if (rc != OPAL_SUCCESS)
        return -EIO;
    *index += count;
    return count;
}

static ssize_t opal_nvram_write(char *buf, size_t count, loff_t *index)
{
    s64 rc = OPAL_BUSY;
    int off;

    if (*index >= nvram_size)
        return 0;
    off = *index;
    if ((off + count) > nvram_size)
        count = nvram_size - off;

    while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
        rc = opal_write_nvram(__pa(buf), count, off);
        if (rc == OPAL_BUSY_EVENT)
            opal_poll_events(NULL);
    }
    *index += count;
    return count;
}

void __init opal_nvram_init(void)
{
    struct device_node *np;
    const u32 *nbytes_p;

    np = of_find_compatible_node(NULL, NULL, "ibm,opal-nvram");
    if (np == NULL)
        return;

    nbytes_p = of_get_property(np, "#bytes", NULL);
    if (!nbytes_p) {
        of_node_put(np);
        return;
    }
    nvram_size = *nbytes_p;

    printk(KERN_INFO "OPAL nvram setup, %u bytes\n", nvram_size);
    of_node_put(np);

    ppc_md.nvram_read = opal_nvram_read;
    ppc_md.nvram_write = opal_nvram_write;
    ppc_md.nvram_size = opal_nvram_size;
}