/*
 *  linux/arch/ppc/kernel/prep_nvram.c
 *
 *  Copyright (C) 1998  Corey Minyard
 *
 */
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/malloc.h>
#include <linux/ioport.h>

#include <asm/segment.h>
#include <asm/io.h>
#include <asm/processor.h>
#include <asm/machdep.h>
#include <asm/prep_nvram.h>

/*
 * Allow for a maximum of 32K of PReP NvRAM data
 */
#define MAX_PREP_NVRAM 0x8000
static char nvramData[MAX_PREP_NVRAM];
static NVRAM_MAP *nvram=(NVRAM_MAP *)&nvramData[0];

#define PREP_NVRAM_AS0	0x74
#define PREP_NVRAM_AS1	0x75
#define PREP_NVRAM_DATA	0x77

unsigned char *rs_pcNvRAM;

unsigned char prep_nvram_read_val(int addr)
{
	outb(addr, PREP_NVRAM_AS0);
	outb(addr>>8, PREP_NVRAM_AS1);
	return inb(PREP_NVRAM_DATA);
}
  
void prep_nvram_write_val(int           addr,
			  unsigned char val)
{
	outb(addr, PREP_NVRAM_AS0);
	outb(addr>>8, PREP_NVRAM_AS1);
   	outb(val, PREP_NVRAM_DATA);
}
  
/*
 * Most Radstone boards have NvRAM memory mapped at offset 8M in ISA space
 */
unsigned char rs_nvram_read_val(int addr)
{
	return rs_pcNvRAM[addr];
}
  
void rs_nvram_write_val(int addr,
			unsigned char val)
{
	rs_pcNvRAM[addr]=val;
}
  
__initfunc(void init_prep_nvram(void))
{
	unsigned char *nvp;
	int  i;
	int  nvramSize;

	/*
	 * I'm making the assumption that 32k will always cover the
	 * nvramsize.  If this isn't the case please let me know and we can
	 * map the header, then get the size from the header, then map
	 * the whole size. -- Cort
	 */
	if ( _prep_type == _PREP_Radstone )
		rs_pcNvRAM = (unsigned char *)ioremap(_ISA_MEM_BASE+0x00800000,
						      32<<10);
	request_region(PREP_NVRAM_AS0, 0x8, "PReP NVRAM");
	/*
	 * The following could fail if the NvRAM were corrupt but
	 * we expect the boot firmware to have checked its checksum
	 * before boot
	 */
	nvp = (char *) &nvram->Header;
	for (i=0; i<sizeof(HEADER); i++)
	{
		*nvp = ppc_md.nvram_read_val(i);
		nvp++;
	}
	
	/*
	 * The PReP NvRAM may be any size so read in the header to
	 * determine how much we must read in order to get the complete
	 * GE area
	 */
	nvramSize=(int)nvram->Header.GEAddress+nvram->Header.GELength;
	if(nvramSize>MAX_PREP_NVRAM)
	{
		/*
		 * NvRAM is too large
		 */
		nvram->Header.GELength=0;
		return;
	}

	/*
	 * Read the remainder of the PReP NvRAM
	 */
	nvp = (char *) &nvram->GEArea[0];
	for (i=sizeof(HEADER); i<nvramSize; i++)
	{
		*nvp = ppc_md.nvram_read_val(i);
		nvp++;
	}
}

__prep
char *prep_nvram_get_var(const char *name)
{
	char *cp;
	int  namelen;

	namelen = strlen(name);
	cp = prep_nvram_first_var();
	while (cp != NULL) {
		if ((strncmp(name, cp, namelen) == 0)
		    && (cp[namelen] == '='))
		{
			return cp+namelen+1;
		}
		cp = prep_nvram_next_var(cp);
	}

	return NULL;
}

__prep
char *prep_nvram_first_var(void)
{
        if (nvram->Header.GELength == 0) {
		return NULL;
	} else {
		return (((char *)nvram)
			+ ((unsigned int) nvram->Header.GEAddress));
	}
}

__prep
char *prep_nvram_next_var(char *name)
{
	char *cp;


	cp = name;
	while (((cp - ((char *) nvram->GEArea)) < nvram->Header.GELength)
	       && (*cp != '\0'))
	{
		cp++;
	}

	/* Skip over any null characters. */
	while (((cp - ((char *) nvram->GEArea)) < nvram->Header.GELength)
	       && (*cp == '\0'))
	{
		cp++;
	}

	if ((cp - ((char *) nvram->GEArea)) < nvram->Header.GELength) {
		return cp;
	} else {
		return NULL;
	}
}