ee_rom.c

来自「TCP-IP红宝书源代码」· C语言 代码 · 共 84 行

/* ee_rom - ee_romread */

#include <conf.h>
#include <kernel.h>
#include <network.h>
#include <i386.h>
#include <ee.h>

#define	ROMDELAY()	{ delay(1); }

/*------------------------------------------------------------------------
 * ee_romread - read PROM data
 *------------------------------------------------------------------------
 */
unsigned short
ee_romread(csr, from)
int		csr;		/* base I/O address		*/
int		from;		/* EEPROM offset (words)	*/
{
	unsigned char	data, out;
	unsigned short	rv;
	int		i;

	outb(csr + EEC, EEC_586R);	/* reset 586		*/
	ROMDELAY();
	outb(csr + EEC, EEC_586R|EEC_GAR);
	/* board docs say wait 240us after reset; we use 500us to
	 * be conservative.
	 */
	delay(50);
	outb(csr + EEC, EEC_586R);
	ROMDELAY();
	outb(csr + EEC, 0);

	out = EEC_586R|EEC_CS;
	outb(csr + EEC, out);		/* select PROM		*/
	ROMDELAY();

	ee_romwrite(csr, EEX_READ, 3);
	ee_romwrite(csr, from, 6);	/* max 64 16-bit regs	*/
	rv = 0;
	for (i=0; i<16; ++i) {
		outb(csr+EEC, out | EEC_SK);
		ROMDELAY();
		data = inb(csr+EEC);
		data &= EEC_DO;
		rv <<= 1;
		rv |= ((unsigned short)data >> 3);
		outb(csr+EEC, out & ~EEC_SK);
		ROMDELAY();
	}

	outb(csr + EEC, 0);	/* clear 586 reset */
	return rv;
}

ee_romwrite(csr, offset, nbits)
int	csr;
int	offset;
int	nbits;
{
	unsigned char	x;
	unsigned short	mask;

	x = EEC_586R | EEC_CS;
	for (mask = 1 << (nbits - 1); mask != 0; mask >>= 1) {
		x &= 0xFB;
		if ((offset & mask) != 0)
			x |= EEC_DI;
		outb(csr+EEC, x);
		ROMDELAY();
		
		/* clock */
		outb(csr+EEC, x | EEC_SK);
		ROMDELAY()
		outb(csr+EEC, x & ~EEC_SK);
		ROMDELAY();
	}
	outb(csr+EEC, x & 0xFB);
}


struct etdev	ee[Neth];	/* should be "Nee" */