/*
 *  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;
	unsigned int *nbytes_p, proplen;

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

	nbytes_p = (unsigned int *)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;
}