LXR linux/arch/powerpc/platforms/chrp/nvram.c

   1/*
   2 *  c 2001 PPC 64 Team, IBM Corp
   3 *
   4 *      This program is free software; you can redistribute it and/or
   5 *      modify it under the terms of the GNU General Public License
   6 *      as published by the Free Software Foundation; either version
   7 *      2 of the License, or (at your option) any later version.
   8 *
   9 * /dev/nvram driver for PPC
  10 *
  11 */
  12
  13#include <linux/kernel.h>
  14#include <linux/init.h>
  15#include <linux/slab.h>
  16#include <linux/spinlock.h>
  17#include <asm/uaccess.h>
  18#include <asm/prom.h>
  19#include <asm/machdep.h>
  20#include <asm/rtas.h>
  21#include "chrp.h"
  22
  23static unsigned int nvram_size;
  24static unsigned char nvram_buf[4];
  25static DEFINE_SPINLOCK(nvram_lock);
  26
  27static unsigned char chrp_nvram_read(int addr)
  28{
  29        unsigned int done;
  30        unsigned long flags;
  31        unsigned char ret;
  32
  33        if (addr >= nvram_size) {
  34                printk(KERN_DEBUG "%s: read addr %d > nvram_size %u\n",
  35                       current->comm, addr, nvram_size);
  36                return 0xff;
  37        }
  38        spin_lock_irqsave(&nvram_lock, flags);
  39        if ((rtas_call(rtas_token("nvram-fetch"), 3, 2, &done, addr,
  40                       __pa(nvram_buf), 1) != 0) || 1 != done)
  41                ret = 0xff;
  42        else
  43                ret = nvram_buf[0];
  44        spin_unlock_irqrestore(&nvram_lock, flags);
  45
  46        return ret;
  47}
  48
  49static void chrp_nvram_write(int addr, unsigned char val)
  50{
  51        unsigned int done;
  52        unsigned long flags;
  53
  54        if (addr >= nvram_size) {
  55                printk(KERN_DEBUG "%s: write addr %d > nvram_size %u\n",
  56                       current->comm, addr, nvram_size);
  57                return;
  58        }
  59        spin_lock_irqsave(&nvram_lock, flags);
  60        nvram_buf[0] = val;
  61        if ((rtas_call(rtas_token("nvram-store"), 3, 2, &done, addr,
  62                       __pa(nvram_buf), 1) != 0) || 1 != done)
  63                printk(KERN_DEBUG "rtas IO error storing 0x%02x at %d", val, addr);
  64        spin_unlock_irqrestore(&nvram_lock, flags);
  65}
  66
  67void __init chrp_nvram_init(void)
  68{
  69        struct device_node *nvram;
  70        const unsigned int *nbytes_p;
  71        unsigned int proplen;
  72
  73        nvram = of_find_node_by_type(NULL, "nvram");
  74        if (nvram == NULL)
  75                return;
  76
  77        nbytes_p = of_get_property(nvram, "#bytes", &proplen);
  78        if (nbytes_p == NULL || proplen != sizeof(unsigned int))
  79                return;
  80
  81        nvram_size = *nbytes_p;
  82
  83        printk(KERN_INFO "CHRP nvram contains %u bytes\n", nvram_size);
  84        of_node_put(nvram);
  85
  86        ppc_md.nvram_read_val = chrp_nvram_read;
  87        ppc_md.nvram_write_val = chrp_nvram_write;
  88
  89        return;
  90}
  91