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
  23 static unsigned int nvram_size;
  24 static unsigned char nvram_buf[4];
  25 static DEFINE_SPINLOCK(nvram_lock);
  26
  27 static 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
  49 static 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
  67 void __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 }