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nvram.c

/*
 *  c 2001 PPC 64 Team, IBM Corp
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 *
 * /dev/nvram driver for PPC64
 *
 * This perhaps should live in drivers/char
 */


#include <linux/types.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <asm/uaccess.h>
#include <asm/nvram.h>
#include <asm/rtas.h>
#include <asm/prom.h>
#include <asm/machdep.h>

static unsigned int nvram_size;
static int nvram_fetch, nvram_store;
static char nvram_buf[NVRW_CNT];    /* assume this is in the first 4GB */
static DEFINE_SPINLOCK(nvram_lock);


static ssize_t pSeries_nvram_read(char *buf, size_t count, loff_t *index)
{
      unsigned int i;
      unsigned long len;
      int done;
      unsigned long flags;
      char *p = buf;


      if (nvram_size == 0 || nvram_fetch == RTAS_UNKNOWN_SERVICE)
            return -ENODEV;

      if (*index >= nvram_size)
            return 0;

      i = *index;
      if (i + count > nvram_size)
            count = nvram_size - i;

      spin_lock_irqsave(&nvram_lock, flags);

      for (; count != 0; count -= len) {
            len = count;
            if (len > NVRW_CNT)
                  len = NVRW_CNT;
            
            if ((rtas_call(nvram_fetch, 3, 2, &done, i, __pa(nvram_buf),
                         len) != 0) || len != done) {
                  spin_unlock_irqrestore(&nvram_lock, flags);
                  return -EIO;
            }
            
            memcpy(p, nvram_buf, len);

            p += len;
            i += len;
      }

      spin_unlock_irqrestore(&nvram_lock, flags);
      
      *index = i;
      return p - buf;
}

static ssize_t pSeries_nvram_write(char *buf, size_t count, loff_t *index)
{
      unsigned int i;
      unsigned long len;
      int done;
      unsigned long flags;
      const char *p = buf;

      if (nvram_size == 0 || nvram_store == RTAS_UNKNOWN_SERVICE)
            return -ENODEV;

      if (*index >= nvram_size)
            return 0;

      i = *index;
      if (i + count > nvram_size)
            count = nvram_size - i;

      spin_lock_irqsave(&nvram_lock, flags);

      for (; count != 0; count -= len) {
            len = count;
            if (len > NVRW_CNT)
                  len = NVRW_CNT;

            memcpy(nvram_buf, p, len);

            if ((rtas_call(nvram_store, 3, 2, &done, i, __pa(nvram_buf),
                         len) != 0) || len != done) {
                  spin_unlock_irqrestore(&nvram_lock, flags);
                  return -EIO;
            }
            
            p += len;
            i += len;
      }
      spin_unlock_irqrestore(&nvram_lock, flags);
      
      *index = i;
      return p - buf;
}

static ssize_t pSeries_nvram_get_size(void)
{
      return nvram_size ? nvram_size : -ENODEV;
}

int __init pSeries_nvram_init(void)
{
      struct device_node *nvram;
      const unsigned int *nbytes_p;
      unsigned int proplen;

      nvram = of_find_node_by_type(NULL, "nvram");
      if (nvram == NULL)
            return -ENODEV;

      nbytes_p = of_get_property(nvram, "#bytes", &proplen);
      if (nbytes_p == NULL || proplen != sizeof(unsigned int))
            return -EIO;

      nvram_size = *nbytes_p;

      nvram_fetch = rtas_token("nvram-fetch");
      nvram_store = rtas_token("nvram-store");
      printk(KERN_INFO "PPC64 nvram contains %d bytes\n", nvram_size);
      of_node_put(nvram);

      ppc_md.nvram_read = pSeries_nvram_read;
      ppc_md.nvram_write      = pSeries_nvram_write;
      ppc_md.nvram_size = pSeries_nvram_get_size;

      return 0;
}

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