156 lines
3.9 KiB
C
156 lines
3.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
// LPC variant I/O for Microchip EC
|
|
//
|
|
// Copyright (C) 2016 Google, Inc
|
|
|
|
#include <linux/delay.h>
|
|
#include <linux/io.h>
|
|
#include <linux/mutex.h>
|
|
#include <linux/types.h>
|
|
|
|
#include "cros_ec_lpc_mec.h"
|
|
|
|
/*
|
|
* This mutex must be held while accessing the EMI unit. We can't rely on the
|
|
* EC mutex because memmap data may be accessed without it being held.
|
|
*/
|
|
static struct mutex io_mutex;
|
|
static u16 mec_emi_base, mec_emi_end;
|
|
|
|
/**
|
|
* cros_ec_lpc_mec_emi_write_address() - Initialize EMI at a given address.
|
|
*
|
|
* @addr: Starting read / write address
|
|
* @access_type: Type of access, typically 32-bit auto-increment
|
|
*/
|
|
static void cros_ec_lpc_mec_emi_write_address(u16 addr,
|
|
enum cros_ec_lpc_mec_emi_access_mode access_type)
|
|
{
|
|
outb((addr & 0xfc) | access_type, MEC_EMI_EC_ADDRESS_B0(mec_emi_base));
|
|
outb((addr >> 8) & 0x7f, MEC_EMI_EC_ADDRESS_B1(mec_emi_base));
|
|
}
|
|
|
|
/**
|
|
* cros_ec_lpc_mec_in_range() - Determine if addresses are in MEC EMI range.
|
|
*
|
|
* @offset: Address offset
|
|
* @length: Number of bytes to check
|
|
*
|
|
* Return: 1 if in range, 0 if not, and -EINVAL on failure
|
|
* such as the mec range not being initialized
|
|
*/
|
|
int cros_ec_lpc_mec_in_range(unsigned int offset, unsigned int length)
|
|
{
|
|
if (length == 0)
|
|
return -EINVAL;
|
|
|
|
if (WARN_ON(mec_emi_base == 0 || mec_emi_end == 0))
|
|
return -EINVAL;
|
|
|
|
if (offset >= mec_emi_base && offset < mec_emi_end) {
|
|
if (WARN_ON(offset + length - 1 >= mec_emi_end))
|
|
return -EINVAL;
|
|
return 1;
|
|
}
|
|
|
|
if (WARN_ON(offset + length > mec_emi_base && offset < mec_emi_end))
|
|
return -EINVAL;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* cros_ec_lpc_io_bytes_mec() - Read / write bytes to MEC EMI port.
|
|
*
|
|
* @io_type: MEC_IO_READ or MEC_IO_WRITE, depending on request
|
|
* @offset: Base read / write address
|
|
* @length: Number of bytes to read / write
|
|
* @buf: Destination / source buffer
|
|
*
|
|
* Return: 8-bit checksum of all bytes read / written
|
|
*/
|
|
u8 cros_ec_lpc_io_bytes_mec(enum cros_ec_lpc_mec_io_type io_type,
|
|
unsigned int offset, unsigned int length,
|
|
u8 *buf)
|
|
{
|
|
int i = 0;
|
|
int io_addr;
|
|
u8 sum = 0;
|
|
enum cros_ec_lpc_mec_emi_access_mode access, new_access;
|
|
|
|
/* Return checksum of 0 if window is not initialized */
|
|
WARN_ON(mec_emi_base == 0 || mec_emi_end == 0);
|
|
if (mec_emi_base == 0 || mec_emi_end == 0)
|
|
return 0;
|
|
|
|
/*
|
|
* Long access cannot be used on misaligned data since reading B0 loads
|
|
* the data register and writing B3 flushes.
|
|
*/
|
|
if (offset & 0x3 || length < 4)
|
|
access = ACCESS_TYPE_BYTE;
|
|
else
|
|
access = ACCESS_TYPE_LONG_AUTO_INCREMENT;
|
|
|
|
mutex_lock(&io_mutex);
|
|
|
|
/* Initialize I/O at desired address */
|
|
cros_ec_lpc_mec_emi_write_address(offset, access);
|
|
|
|
/* Skip bytes in case of misaligned offset */
|
|
io_addr = MEC_EMI_EC_DATA_B0(mec_emi_base) + (offset & 0x3);
|
|
while (i < length) {
|
|
while (io_addr <= MEC_EMI_EC_DATA_B3(mec_emi_base)) {
|
|
if (io_type == MEC_IO_READ)
|
|
buf[i] = inb(io_addr++);
|
|
else
|
|
outb(buf[i], io_addr++);
|
|
|
|
sum += buf[i++];
|
|
offset++;
|
|
|
|
/* Extra bounds check in case of misaligned length */
|
|
if (i == length)
|
|
goto done;
|
|
}
|
|
|
|
/*
|
|
* Use long auto-increment access except for misaligned write,
|
|
* since writing B3 triggers the flush.
|
|
*/
|
|
if (length - i < 4 && io_type == MEC_IO_WRITE)
|
|
new_access = ACCESS_TYPE_BYTE;
|
|
else
|
|
new_access = ACCESS_TYPE_LONG_AUTO_INCREMENT;
|
|
|
|
if (new_access != access ||
|
|
access != ACCESS_TYPE_LONG_AUTO_INCREMENT) {
|
|
access = new_access;
|
|
cros_ec_lpc_mec_emi_write_address(offset, access);
|
|
}
|
|
|
|
/* Access [B0, B3] on each loop pass */
|
|
io_addr = MEC_EMI_EC_DATA_B0(mec_emi_base);
|
|
}
|
|
|
|
done:
|
|
mutex_unlock(&io_mutex);
|
|
|
|
return sum;
|
|
}
|
|
EXPORT_SYMBOL(cros_ec_lpc_io_bytes_mec);
|
|
|
|
void cros_ec_lpc_mec_init(unsigned int base, unsigned int end)
|
|
{
|
|
mutex_init(&io_mutex);
|
|
mec_emi_base = base;
|
|
mec_emi_end = end;
|
|
}
|
|
EXPORT_SYMBOL(cros_ec_lpc_mec_init);
|
|
|
|
void cros_ec_lpc_mec_destroy(void)
|
|
{
|
|
mutex_destroy(&io_mutex);
|
|
}
|
|
EXPORT_SYMBOL(cros_ec_lpc_mec_destroy);
|