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