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/*
* (C) Copyright 2001
* Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com.
*
* See file CREDITS for list of people who contributed to this
* project.
*
* 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.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*/
/*
* This provides a bit-banged interface to the ethernet MII management
* channel.
*/
#include <common.h>
#include <ioports.h>
#include <ppc_asm.tmpl>
#ifdef CONFIG_BITBANGMII
/*****************************************************************************
*
* Utility to send the preamble, address, and register (common to read
* and write).
*/
static void miiphy_pre (char read, unsigned char addr, unsigned char reg)
{
int j; /* counter */
#ifndef CONFIG_EP8248
volatile ioport_t *iop = ioport_addr ((immap_t *) CFG_IMMR, MDIO_PORT);
#endif
/*
* Send a 32 bit preamble ('1's) with an extra '1' bit for good measure.
* The IEEE spec says this is a PHY optional requirement. The AMD
* 79C874 requires one after power up and one after a MII communications
* error. This means that we are doing more preambles than we need,
* but it is safer and will be much more robust.
*/
MDIO_ACTIVE;
MDIO (1);
for (j = 0; j < 32; j++) {
MDC (0);
MIIDELAY;
MDC (1);
MIIDELAY;
}
/* send the start bit (01) and the read opcode (10) or write (10) */
MDC (0);
MDIO (0);
MIIDELAY;
MDC (1);
MIIDELAY;
MDC (0);
MDIO (1);
MIIDELAY;
MDC (1);
MIIDELAY;
MDC (0);
MDIO (read);
MIIDELAY;
MDC (1);
MIIDELAY;
MDC (0);
MDIO (!read);
MIIDELAY;
MDC (1);
MIIDELAY;
/* send the PHY address */
for (j = 0; j < 5; j++) {
MDC (0);
if ((addr & 0x10) == 0) {
MDIO (0);
} else {
MDIO (1);
}
MIIDELAY;
MDC (1);
MIIDELAY;
addr <<= 1;
}
/* send the register address */
for (j = 0; j < 5; j++) {
MDC (0);
if ((reg & 0x10) == 0) {
MDIO (0);
} else {
MDIO (1);
}
MIIDELAY;
MDC (1);
MIIDELAY;
reg <<= 1;
}
}
/*****************************************************************************
*
* Read a MII PHY register.
*
* Returns:
* 0 on success
*/
int miiphy_read (unsigned char addr, unsigned char reg, unsigned short *value)
{
short rdreg; /* register working value */
int j; /* counter */
#ifndef CONFIG_EP8248
volatile ioport_t *iop = ioport_addr ((immap_t *) CFG_IMMR, MDIO_PORT);
#endif
miiphy_pre (1, addr, reg);
/* tri-state our MDIO I/O pin so we can read */
MDC (0);
MDIO_TRISTATE;
MIIDELAY;
MDC (1);
MIIDELAY;
/* check the turnaround bit: the PHY should be driving it to zero */
if (MDIO_READ != 0) {
/* puts ("PHY didn't drive TA low\n"); */
for (j = 0; j < 32; j++) {
MDC (0);
MIIDELAY;
MDC (1);
MIIDELAY;
}
return (-1);
}
MDC (0);
MIIDELAY;
/* read 16 bits of register data, MSB first */
rdreg = 0;
for (j = 0; j < 16; j++) {
MDC (1);
MIIDELAY;
rdreg <<= 1;
rdreg |= MDIO_READ;
MDC (0);
MIIDELAY;
}
MDC (1);
MIIDELAY;
MDC (0);
MIIDELAY;
MDC (1);
MIIDELAY;
*value = rdreg;
#ifdef DEBUG
printf ("miiphy_read(0x%x) @ 0x%x = 0x%04x\n", reg, addr, *value);
#endif
return 0;
}
/*****************************************************************************
*
* Write a MII PHY register.
*
* Returns:
* 0 on success
*/
int miiphy_write (unsigned char addr, unsigned char reg, unsigned short value)
{
int j; /* counter */
#ifndef CONFIG_EP8248
volatile ioport_t *iop = ioport_addr ((immap_t *) CFG_IMMR, MDIO_PORT);
#endif
miiphy_pre (0, addr, reg);
/* send the turnaround (10) */
MDC (0);
MDIO (1);
MIIDELAY;
MDC (1);
MIIDELAY;
MDC (0);
MDIO (0);
MIIDELAY;
MDC (1);
MIIDELAY;
/* write 16 bits of register data, MSB first */
for (j = 0; j < 16; j++) {
MDC (0);
if ((value & 0x00008000) == 0) {
MDIO (0);
} else {
MDIO (1);
}
MIIDELAY;
MDC (1);
MIIDELAY;
value <<= 1;
}
/*
* Tri-state the MDIO line.
*/
MDIO_TRISTATE;
MDC (0);
MIIDELAY;
MDC (1);
MIIDELAY;
return 0;
}
#endif /* CONFIG_BITBANGMII */
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