linux/arch/powerpc/platforms/chrp/nvram.c
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   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/spinlock.h>
  16#include <asm/uaccess.h>
  17#include <asm/prom.h>
  18#include <asm/machdep.h>
  19#include <asm/rtas.h>
  20#include "chrp.h"
  21
  22static unsigned int nvram_size;
  23static unsigned char nvram_buf[4];
  24static DEFINE_SPINLOCK(nvram_lock);
  25
  26static unsigned char chrp_nvram_read(int addr)
  27{
  28        unsigned int done;
  29        unsigned long flags;
  30        unsigned char ret;
  31
  32        if (addr >= nvram_size) {
  33                printk(KERN_DEBUG "%s: read addr %d > nvram_size %u\n",
  34                       current->comm, addr, nvram_size);
  35                return 0xff;
  36        }
  37        spin_lock_irqsave(&nvram_lock, flags);
  38        if ((rtas_call(rtas_token("nvram-fetch"), 3, 2, &done, addr,
  39                       __pa(nvram_buf), 1) != 0) || 1 != done)
  40                ret = 0xff;
  41        else
  42                ret = nvram_buf[0];
  43        spin_unlock_irqrestore(&nvram_lock, flags);
  44
  45        return ret;
  46}
  47
  48static void chrp_nvram_write(int addr, unsigned char val)
  49{
  50        unsigned int done;
  51        unsigned long flags;
  52
  53        if (addr >= nvram_size) {
  54                printk(KERN_DEBUG "%s: write addr %d > nvram_size %u\n",
  55                       current->comm, addr, nvram_size);
  56                return;
  57        }
  58        spin_lock_irqsave(&nvram_lock, flags);
  59        nvram_buf[0] = val;
  60        if ((rtas_call(rtas_token("nvram-store"), 3, 2, &done, addr,
  61                       __pa(nvram_buf), 1) != 0) || 1 != done)
  62                printk(KERN_DEBUG "rtas IO error storing 0x%02x at %d", val, addr);
  63        spin_unlock_irqrestore(&nvram_lock, flags);
  64}
  65
  66void __init chrp_nvram_init(void)
  67{
  68        struct device_node *nvram;
  69        const unsigned int *nbytes_p;
  70        unsigned int proplen;
  71
  72        nvram = of_find_node_by_type(NULL, "nvram");
  73        if (nvram == NULL)
  74                return;
  75
  76        nbytes_p = of_get_property(nvram, "#bytes", &proplen);
  77        if (nbytes_p == NULL || proplen != sizeof(unsigned int)) {
  78                of_node_put(nvram);
  79                return;
  80        }
  81
  82        nvram_size = *nbytes_p;
  83
  84        printk(KERN_INFO "CHRP nvram contains %u bytes\n", nvram_size);
  85        of_node_put(nvram);
  86
  87        ppc_md.nvram_read_val = chrp_nvram_read;
  88        ppc_md.nvram_write_val = chrp_nvram_write;
  89
  90        return;
  91}
  92