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/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
  22 static unsigned int nvram_size;
  23 static unsigned char nvram_buf[4];
  24 static DEFINE_SPINLOCK(nvram_lock);
  25
  26 static 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
  48 static 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
  66 void __init chrp_nvram_init(void)
  67 {
  68         struct device_node *nvram;
  69         const __be32 *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 = be32_to_cpup(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 }