/*
 * Copyright (C) 2012 Michael Brown <mbrown@fensystems.co.uk>.
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 *
 * You can also choose to distribute this program under the terms of
 * the Unmodified Binary Distribution Licence (as given in the file
 * COPYING.UBDL), provided that you have satisfied its requirements.
 */

FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );

#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <ipxe/mii.h>

/** @file
 *
 * Media Independent Interface
 *
 */

/**
 * Restart autonegotiation
 *
 * @v mii		MII device
 * @ret rc		Return status code
 */
int mii_restart ( struct mii_device *mii ) {
	int bmcr;
	int rc;

	/* Read BMCR */
	bmcr = mii_read ( mii, MII_BMCR );
	if ( bmcr < 0 ) {
		rc = bmcr;
		DBGC ( mii, "MII %p could not read BMCR: %s\n",
		       mii, strerror ( rc ) );
		return rc;
	}

	/* Enable and restart autonegotiation */
	bmcr |= ( BMCR_ANENABLE | BMCR_ANRESTART );
	if ( ( rc = mii_write ( mii, MII_BMCR, bmcr ) ) != 0 ) {
		DBGC ( mii, "MII %p could not write BMCR: %s\n",
		       mii, strerror ( rc ) );
		return rc;
	}

	DBGC ( mii, "MII %p restarted autonegotiation\n", mii );
	return 0;
}

/**
 * Reset MII device
 *
 * @v mii		MII device
 * @ret rc		Return status code
 */
int mii_reset ( struct mii_device *mii ) {
	unsigned int i;
	int bmcr;
	int rc;

	/* Power-up, enable autonegotiation and initiate reset */
	if ( ( rc = mii_write ( mii, MII_BMCR,
				( BMCR_RESET | BMCR_ANENABLE ) ) ) != 0 ) {
		DBGC ( mii, "MII %p could not write BMCR: %s\n",
		       mii, strerror ( rc ) );
		return rc;
	}

	/* Wait for reset to complete */
	for ( i = 0 ; i < MII_RESET_MAX_WAIT_MS ; i++ ) {

		/* Check if reset has completed */
		bmcr = mii_read ( mii, MII_BMCR );
		if ( bmcr < 0 ) {
			rc = bmcr;
			DBGC ( mii, "MII %p could not read BMCR: %s\n",
			       mii, strerror ( rc ) );
			return rc;
		}

		/* If reset is not complete, delay 1ms and retry */
		if ( bmcr & BMCR_RESET ) {
			mdelay ( 1 );
			continue;
		}

		/* Force autonegotation on again, in case it was
		 * cleared by the reset.
		 */
		if ( ( rc = mii_restart ( mii ) ) != 0 )
			return rc;

		DBGC ( mii, "MII %p reset after %dms\n", mii, i );
		return 0;
	}

	DBGC ( mii, "MII %p timed out waiting for reset\n", mii );
	return -ETIMEDOUT;
}

/**
 * Update link status via MII
 *
 * @v mii		MII device
 * @v netdev		Network device
 * @ret rc		Return status code
 */
int mii_check_link ( struct mii_device *mii, struct net_device *netdev ) {
	int bmsr;
	int link;
	int rc;

	/* Read BMSR */
	bmsr = mii_read ( mii, MII_BMSR );
	if ( bmsr < 0 ) {
		rc = bmsr;
		return rc;
	}

	/* Report link status */
	link = ( bmsr & BMSR_LSTATUS );
	DBGC ( mii, "MII %p link %s (BMSR %#04x)\n",
	       mii, ( link ? "up" : "down" ), bmsr );
	if ( link ) {
		netdev_link_up ( netdev );
	} else {
		netdev_link_down ( netdev );
	}

	return 0;
}

/**
 * Find PHY address
 *
 * @v mii		MII device
 * @ret rc		Return status code
 */
int mii_find ( struct mii_device *mii ) {
	unsigned int address;
	int id;

	/* Try all possible PHY addresses */
	for ( address = 0 ; address <= MII_MAX_PHY_ADDRESS ; address++ ) {
		mii->address = address;
		id = mii_read ( mii, MII_PHYSID1 );
		if ( ( id > 0x0000 ) && ( id < 0xffff ) ) {
			DBGC ( mii, "MII %p found PHY at address %d\n",
			       mii, address );
			return 0;
		}
	}

	DBGC ( mii, "MII %p failed to find an address\n", mii );
	return -ENOENT;
}