/*
 * Copyright (C) 2010 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 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., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

FILE_LICENCE ( GPL2_OR_LATER );

#include <stdint.h>
#include <unistd.h>
#include <errno.h>
#include <byteswap.h>
#include <ipxe/pci.h>
#include <ipxe/isapnp.h>
#include <ipxe/pcivpd.h>

/** @file
 *
 * PCI Vital Product Data
 *
 */

/**
 * Initialise PCI Vital Product Data
 *
 * @v vpd		PCI VPD
 * @v pci		PCI device
 * @ret rc		Return status code
 */
int pci_vpd_init ( struct pci_vpd *vpd, struct pci_device *pci ) {

	/* Initialise structure */
	vpd->pci = pci;
	pci_vpd_invalidate_cache ( vpd );

	/* Locate VPD capability */
	vpd->cap = pci_find_capability ( pci, PCI_CAP_ID_VPD );
	if ( ! vpd->cap ) {
		DBGC ( vpd, PCI_FMT " does not support VPD\n",
		       PCI_ARGS ( pci ) );
		return -ENOTTY;
	}

	DBGC ( vpd, PCI_FMT " VPD is at offset %02x\n",
	       PCI_ARGS ( pci ), vpd->cap );
	return 0;
}

/**
 * Read one dword of PCI Vital Product Data
 *
 * @v vpd		PCI VPD
 * @v address		Address to read
 * @ret data		Read data
 * @ret rc		Return status code
 */
static int pci_vpd_read_dword ( struct pci_vpd *vpd, int address,
				uint32_t *data ) {
	struct pci_device *pci = vpd->pci;
	unsigned int cap = vpd->cap;
	unsigned int retries;
	uint16_t flag;

	/* Return cached value, if present */
	if ( pci_vpd_cache_is_valid ( vpd ) &&
	     ( vpd->cache.address == address ) ) {
		*data = vpd->cache.data;
		return 0;
	}

	/* Initiate read */
	pci_write_config_word ( pci, ( cap + PCI_VPD_ADDRESS ), address );

	/* Wait for read to complete */
	for ( retries = 0 ; retries < PCI_VPD_MAX_WAIT_MS ; retries++ ) {

		/* Check if data is ready */
		pci_read_config_word ( pci, ( cap + PCI_VPD_ADDRESS ), &flag );
		if ( flag & PCI_VPD_FLAG ) {

			/* Read data */
			pci_read_config_dword ( pci, ( cap + PCI_VPD_DATA ),
						data );
			DBGC2 ( vpd, PCI_FMT " VPD %04x => %08x\n",
				PCI_ARGS ( pci ), address, htonl ( *data ) );

			/* Populate cache */
			vpd->cache.address = address;
			vpd->cache.data = *data;

			return 0;
		}

		/* Wait 1ms before retrying */
		mdelay ( 1 );
	}

	DBGC ( vpd, PCI_FMT " VPD %04x read via %02x timed out\n",
	       PCI_ARGS ( pci ), address, cap );
	return -ETIMEDOUT;
}

/**
 * Write one dword of PCI Vital Product Data
 *
 * @v vpd		PCI VPD
 * @v address		Address to write
 * @v data		Data to write
 * @ret rc		Return status code
 */
static int pci_vpd_write_dword ( struct pci_vpd *vpd, int address,
				 uint32_t data ) {
	struct pci_device *pci = vpd->pci;
	unsigned int cap = vpd->cap;
	unsigned int retries;
	uint16_t flag;

	/* Invalidate cache */
	pci_vpd_invalidate_cache ( vpd );

	DBGC2 ( vpd, PCI_FMT " VPD %04x <= %08x\n",
		PCI_ARGS ( pci ), address, htonl ( data ) );

	/* Write data */
	pci_write_config_dword ( pci, ( cap + PCI_VPD_DATA ), data );

	/* Initiate write */
	pci_write_config_word ( pci, ( cap + PCI_VPD_ADDRESS ),
				( address | PCI_VPD_FLAG ) );

	/* Wait for write to complete */
	for ( retries = 0 ; retries < PCI_VPD_MAX_WAIT_MS ; retries++ ) {

		/* Check if write has completed */
		pci_read_config_word ( pci, ( cap + PCI_VPD_ADDRESS ), &flag );
		if ( ! ( flag & PCI_VPD_FLAG ) )
			return 0;

		/* Wait 1ms before retrying */
		mdelay ( 1 );
	}

	DBGC ( vpd, PCI_FMT " VPD %04x write via %02x timed out\n",
	       PCI_ARGS ( pci ), address, cap );
	return -ETIMEDOUT;
}

/**
 * Read PCI VPD
 *
 * @v vpd		PCI VPD
 * @v address		Starting address
 * @v buf		Data buffer
 * @v len		Length of data buffer
 * @ret rc		Return status code
 */
int pci_vpd_read ( struct pci_vpd *vpd, unsigned int address, void *buf,
		   size_t len ) {
	uint8_t *bytes = buf;
	uint32_t data;
	size_t skip_len;
	unsigned int i;
	int rc;

	/* Calculate length to skip at start of data */
	skip_len = ( address & 0x03 );

	/* Read data, a dword at a time */
	for ( address &= ~0x03 ; len ; address += 4 ) {

		/* Read whole dword */
		if ( ( rc = pci_vpd_read_dword ( vpd, address, &data ) ) != 0 )
			return rc;

		/* Copy data to buffer */
		for ( i = 4 ; i ; i-- ) {
			if ( skip_len ) {
				skip_len--;
			} else if ( len ) {
				*(bytes++) = data;
				len--;
			}
			data = ( ( data << 24 ) | ( data >> 8 ) );
		}
	}

	return 0;
}

/**
 * Write PCI VPD
 *
 * @v vpd		PCI VPD
 * @v address		Starting address
 * @v buf		Data buffer
 * @v len		Length of data buffer
 * @ret rc		Return status code
 */
int pci_vpd_write ( struct pci_vpd *vpd, unsigned int address, const void *buf,
		    size_t len ) {
	const uint8_t *bytes = buf;
	uint32_t data;
	size_t skip_len;
	unsigned int i;
	int rc;

	/* Calculate length to skip at start of data */
	skip_len = ( address & 0x03 );

	/* Write data, a dword at a time */
	for ( address &= ~0x03 ; len ; address += 4 ) {

		/* Read existing dword, if necessary */
		if ( skip_len || ( len <= 0x03 ) ) {
			if ( ( rc = pci_vpd_read_dword ( vpd, address,
							 &data ) ) != 0 )
				return rc;
		}

		/* Copy data from buffer */
		for ( i = 4 ; i ; i-- ) {
			if ( skip_len ) {
				skip_len--;
			} else if ( len ) {
				data = ( ( data & ~0xff ) | *(bytes++) );
				len--;
			}
			data = ( ( data << 24 ) | ( data >> 8 ) );
		}

		/* Write whole dword */
		if ( ( rc = pci_vpd_write_dword ( vpd, address, data ) ) != 0 )
			return rc;
	}
	return 0;
}

/**
 * Dump PCI VPD region (for debugging)
 *
 * @v vpd		PCI VPD
 * @v address		Starting address
 * @v len		Length of data
 */
static void pci_vpd_dump ( struct pci_vpd *vpd, unsigned int address,
			   size_t len ) {
	int rc;

	/* Do nothing in non-debug builds */
	if ( ! DBG_LOG )
		return;

	/* Read data */
	{
		char buf[len];
		if ( ( rc = pci_vpd_read ( vpd, address, buf,
					   sizeof ( buf ) ) ) != 0 )
			return;
		DBGC_HDA ( vpd, address, buf, sizeof ( buf ) );
	}
}

/**
 * Locate PCI VPD tag
 *
 * @v vpd		PCI VPD
 * @v tag		ISAPnP tag
 * @ret address		Address of tag body
 * @ret len		Length of tag body
 * @ret rc		Return status code
 */
static int pci_vpd_find_tag ( struct pci_vpd *vpd, unsigned int tag,
			      unsigned int *address, size_t *len ) {
	uint8_t read_tag;
	uint16_t read_len;
	int rc;

	/* Scan through tags looking for a match */
	*address = 0;
	do {
		/* Read tag byte */
		if ( ( rc = pci_vpd_read ( vpd, (*address)++, &read_tag,
					   sizeof ( read_tag ) ) ) != 0 )
			return rc;

		/* Extract tag and length */
		if ( ISAPNP_IS_LARGE_TAG ( read_tag ) ) {
			if ( ( rc = pci_vpd_read ( vpd, *address, &read_len,
						   sizeof ( read_len ) ) ) != 0)
				return rc;
			*address += sizeof ( read_len );
			read_len = le16_to_cpu ( read_len );
			read_tag = ISAPNP_LARGE_TAG_NAME ( read_tag );
		} else {
			read_len = ISAPNP_SMALL_TAG_LEN ( read_tag );
			read_tag = ISAPNP_SMALL_TAG_NAME ( read_tag );
		}

		/* Check for tag match */
		if ( tag == read_tag ) {
			*len = read_len;
			DBGC ( vpd, PCI_FMT " VPD tag %02x is at "
			       "[%04x,%04zx)\n", PCI_ARGS ( vpd->pci ), tag,
			       *address, ( *address + *len ) );
			return 0;
		}

		/* Move to next tag */
		*address += read_len;

	} while ( read_tag != ISAPNP_TAG_END );

	DBGC ( vpd, PCI_FMT " VPD tag %02x not found\n",
	       PCI_ARGS ( vpd->pci ), tag );
	return -ENOENT;
}

/**
 * Locate PCI VPD field
 *
 * @v vpd		PCI VPD
 * @v field		VPD field descriptor
 * @ret address		Address of field body
 * @ret len		Length of field body
 * @ret rc		Return status code
 */
int pci_vpd_find ( struct pci_vpd *vpd, unsigned int field,
		   unsigned int *address, size_t *len ) {
	struct pci_vpd_field read_field;
	int rc;

	/* Locate containing tag */
	if ( ( rc = pci_vpd_find_tag ( vpd, PCI_VPD_TAG ( field ),
				       address, len ) ) != 0 )
		return rc;

	/* Return immediately if we are searching for a whole-tag field */
	if ( ! PCI_VPD_KEYWORD ( field ) ) {
		pci_vpd_dump ( vpd, *address, *len );
		return 0;
	}

	/* Scan through fields looking for a match */
	while ( *len >= sizeof ( read_field ) ) {

		/* Read field header */
		if ( ( rc = pci_vpd_read ( vpd, *address, &read_field,
					   sizeof ( read_field ) ) ) != 0 )
			return rc;
		*address += sizeof ( read_field );
		*len -= sizeof ( read_field );

		/* Check for keyword match */
		if ( read_field.keyword == PCI_VPD_KEYWORD ( field ) ) {
			*len = read_field.len;
			DBGC ( vpd, PCI_FMT " VPD field " PCI_VPD_FIELD_FMT
			       " is at [%04x,%04zx)\n", PCI_ARGS ( vpd->pci ),
			       PCI_VPD_FIELD_ARGS ( field ),
			       *address, ( *address + *len ) );
			pci_vpd_dump ( vpd, *address, *len );
			return 0;
		}

		/* Move to next field */
		if ( read_field.len > *len )
			break;
		*address += read_field.len;
		*len -= read_field.len;
	}

	DBGC ( vpd, PCI_FMT " VPD field " PCI_VPD_FIELD_FMT " not found\n",
	       PCI_ARGS ( vpd->pci ), PCI_VPD_FIELD_ARGS ( field ) );
	return -ENOENT;
}