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nvram.c

/*
 *  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/slab.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))
            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;
}

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