blob: 06a6bca5530f0f272dfd99a19f4f9a43b36a16b4 [file] [log] [blame]
/*
* This file is part of the coreboot project.
*
* Copyright 2018 Google LLC
*
* 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 <stddef.h>
#include <stdint.h>
#include <arch/io.h>
#include "mec.h"
enum mec_access_mode {
/* 8-bit access */
ACCESS_TYPE_BYTE = 0x0,
/* 16-bit access */
ACCESS_TYPE_WORD = 0x1,
/* 32-bit access */
ACCESS_TYPE_LONG = 0x2,
/*
* 32-bit access, read or write of MEC_EMI_EC_DATA_B3 causes the
* EC data register to be incremented.
*/
ACCESS_TYPE_LONG_AUTO_INCREMENT = 0x3,
};
/* EMI registers are relative to base */
#define MEC_EMI_HOST_TO_EC(base) ((base) + 0)
#define MEC_EMI_EC_TO_HOST(base) ((base) + 1)
#define MEC_EMI_EC_ADDRESS_B0(base) ((base) + 2)
#define MEC_EMI_EC_ADDRESS_B1(base) ((base) + 3)
#define MEC_EMI_EC_DATA_B0(base) ((base) + 4)
#define MEC_EMI_EC_DATA_B1(base) ((base) + 5)
#define MEC_EMI_EC_DATA_B2(base) ((base) + 6)
#define MEC_EMI_EC_DATA_B3(base) ((base) + 7)
/*
* cros_ec_lpc_mec_emi_write_address
*
* Initialize EMI read / write at a given address.
*
* @base: Starting read / write address
* @offset: Offset applied to base address
* @access_mode: Type of access, typically 32-bit auto-increment
*/
static void mec_emi_write_address(uint16_t base, uint16_t offset,
enum mec_access_mode access_mode)
{
outb((offset & 0xfc) | access_mode, MEC_EMI_EC_ADDRESS_B0(base));
outb((offset >> 8) & 0x7f, MEC_EMI_EC_ADDRESS_B1(base));
}
uint8_t mec_io_bytes(enum mec_io_type type, uint16_t base,
uint16_t offset, void *buffer, size_t size)
{
enum mec_access_mode access_mode, new_access_mode;
uint8_t *buf = buffer;
uint8_t checksum = 0;
int io_addr;
int i = 0;
if (size == 0 || base == 0)
return 0;
/*
* Long access cannot be used on misaligned data since reading B0 loads
* the data register and writing B3 flushes it.
*/
if ((offset & 0x3) || (size < 4))
access_mode = ACCESS_TYPE_BYTE;
else
access_mode = ACCESS_TYPE_LONG_AUTO_INCREMENT;
/* Initialize I/O at desired address */
mec_emi_write_address(base, offset, access_mode);
/* Skip bytes in case of misaligned offset */
io_addr = MEC_EMI_EC_DATA_B0(base) + (offset & 0x3);
while (i < size) {
while (io_addr <= MEC_EMI_EC_DATA_B3(base)) {
if (type == MEC_IO_WRITE)
outb(buf[i], io_addr++);
else
buf[i] = inb(io_addr++);
checksum += buf[i++];
offset++;
/* Extra bounds check in case of misaligned size */
if (i == size)
return checksum;
}
/*
* Use long auto-increment access except for misaligned write,
* since writing B3 triggers the flush.
*/
if ((size - i) < 4 && type == MEC_IO_WRITE)
new_access_mode = ACCESS_TYPE_BYTE;
else
new_access_mode = ACCESS_TYPE_LONG_AUTO_INCREMENT;
if (new_access_mode != access_mode ||
access_mode != ACCESS_TYPE_LONG_AUTO_INCREMENT) {
access_mode = new_access_mode;
mec_emi_write_address(base, offset, access_mode);
}
/* Access [B0, B3] on each loop pass */
io_addr = MEC_EMI_EC_DATA_B0(base);
}
return checksum;
}