src/southbridge/amd/cimx/sb700/smbus_spd.c

/*
 * This file is part of the coreboot project.
 *
 * Copyright (C) 2012 Advanced Micro Devices, Inc.
 *
 * 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; version 2 of the License.
 *
 * 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.
 */
#include <device/pci_def.h>
#include <device/device.h>
#include <stdlib.h>
#include "OEM.h"		/* SMBUS0_BASE_ADDRESS */

/* warning: Porting.h includes an open #pragma pack(1) */
#include "Porting.h"
#include "AGESA.h"
#include "amdlib.h"
#include "chip.h"
#include "smbus_spd.h"

#include <northbridge/amd/agesa/dimmSpd.h>

/* uncomment for source level debug - GDB gets really confused otherwise. */
//#pragma optimize ("", off)

/**
 * Read a single SPD byte.  If the first byte is being read, set up the
 * address and offset. Following bytes auto increment.
 */
static UINT8 readSmbusByte(UINT16 iobase, UINT8 address, char *buffer,
						   int offset, int initial_offset)
{
	unsigned int status = -1;
	UINT64 time_limit;

	/* clear status register */
	__outbyte(iobase + SMBUS_STATUS_REG, 0xFF);
	__outbyte(iobase + SMBUS_SLAVE_STATUS_REG, 0x1F);

	if (offset == initial_offset) {
		/* Set offset, set slave address and start reading */
		__outbyte(iobase + SMBUS_CONTROL_REG, offset);
		__outbyte(iobase + SMBUS_HOST_CMD_REG, address | READ_BIT);
		__outbyte(iobase + SMBUS_COMMAND_REG, SMBUS_READ_BYTE_COMMAND);
	} else {
		/* Issue read command - auto increments to next byte */
		__outbyte(iobase + SMBUS_COMMAND_REG, SMBUS_READ_COMMAND);
	}
	/* time limit to avoid hanging for unexpected error status */
	time_limit = __rdtsc() + MAX_READ_TSC_COUNT;
	while (__rdtsc() <= time_limit) {
		status = __inbyte(iobase + SMBUS_STATUS_REG);
		if ((status & SMBUS_INTERRUPT_MASK) == 0)
			continue;	/* SMBusInterrupt not set, keep waiting */
		if ((status & HOSTBUSY_MASK) != 0)
			continue;	/* HostBusy set, keep waiting */
		break;
	}

	if (status != STATUS__COMPLETED_SUCCESSFULLY)
		return AGESA_ERROR;

	buffer[0] = __inbyte(iobase + SMBUS_DATA0_REG);
	return AGESA_SUCCESS;
}

/**
 * Write a single smbus byte.
 */
UINT8 writeSmbusByte(UINT16 iobase, UINT8 address, UINT8 buffer,
					 int offset)
{
	unsigned int status = -1;
	UINT64 time_limit;

	/* clear status register */
	__outbyte(iobase + SMBUS_STATUS_REG, 0xFF);
	__outbyte(iobase + SMBUS_SLAVE_STATUS_REG, 0x1F);

	/* set offset, set slave address, set data and start writing */
	__outbyte(iobase + SMBUS_CONTROL_REG, offset);
	__outbyte(iobase + SMBUS_HOST_CMD_REG, address & (~READ_BIT));
	__outbyte(iobase + SMBUS_DATA0_REG, buffer);
	__outbyte(iobase + SMBUS_COMMAND_REG, SMBUS_WRITE_BYTE_COMMAND);

	/* time limit to avoid hanging for unexpected error status */
	time_limit = __rdtsc() + MAX_READ_TSC_COUNT;
	while (__rdtsc() <= time_limit) {
		status = __inbyte(iobase + SMBUS_STATUS_REG);
		if ((status & SMBUS_INTERRUPT_MASK) == 0)
			continue;	/* SMBusInterrupt not set, keep waiting */
		if ((status & HOSTBUSY_MASK) != 0)
			continue;	/* HostBusy set, keep waiting */
		break;
	}

	if (status != STATUS__COMPLETED_SUCCESSFULLY)
		return AGESA_ERROR;

	return AGESA_SUCCESS;
}

static void setupFch(UINT16 ioBase)
{
	AMD_CONFIG_PARAMS         StdHeader;
	UINT32                    PciData32;
	UINT8                     PciData8;
	PCI_ADDR                  PciAddress;

	/* Set SMBus MMIO. */
	PciAddress.AddressValue = MAKE_SBDFO (0, 0, 20, 0, 0x90);
	PciData32 = (ioBase & 0xFFFFFFF0) | BIT0;
	LibAmdPciWrite(AccessWidth32, PciAddress, &PciData32, &StdHeader);

	/* Enable SMBus MMIO. */
	PciAddress.AddressValue = MAKE_SBDFO (0, 0, 20, 0, 0xD2);
	LibAmdPciRead(AccessWidth8, PciAddress, &PciData8, &StdHeader); ;
	PciData8 |= BIT0;
	LibAmdPciWrite(AccessWidth8, PciAddress, &PciData8, &StdHeader);

	/* Set SMBus clock to 400 KHz */
	__outbyte(ioBase + SMBUS_CLOCK_REG, SMBUS_FREQUENCY_CONST / 400000);
}

/**
 * Read one or more SPD bytes from a DIMM.
 * Start with offset zero and read sequentially.
 * Reads 128 bytes in 7-8 ms at 400 KHz.
 */
static UINT8 readspd(UINT16 iobase, UINT8 SmbusSlaveAddress, char *buffer,
					 UINT16 count)
{
	UINT16 index;
	UINT8 status;
	UINT8 initial_offset = 0;

	setupFch(iobase);

	for (index = initial_offset; index < count; index++) {
		status = readSmbusByte(iobase, SmbusSlaveAddress, &buffer[index], index,
				initial_offset);
		if (status != AGESA_SUCCESS)
			return status;
	}

	return status;
}

int smbus_readSpd(int spdAddress, char *buf, size_t len)
{
	int ioBase = SMBUS0_BASE_ADDRESS;
	setupFch (ioBase);
	return readspd (ioBase, spdAddress, buf, len);
}