/*
* cros_ec_lpc_reg - LPC access to the Chrome OS Embedded Controller
*
* Copyright (C) 2016 Google, Inc
*
* This software is licensed under the terms of the GNU General Public
* License version 2, as published by the Free Software Foundation, and
* may be copied, distributed, and modified under those terms.
*
* 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.
*
* This driver uses the Chrome OS EC byte-level message-based protocol for
* communicating the keyboard state (which keys are pressed) from a keyboard EC
* to the AP over some bus (such as i2c, lpc, spi). The EC does debouncing,
* but everything else (including deghosting) is done here. The main
* motivation for this is to keep the EC firmware as simple as possible, since
* it cannot be easily upgraded and EC flash/IRAM space is relatively
* expensive.
*/
#include <linux/io.h>
#include <linux/mfd/cros_ec.h>
#include <linux/mfd/cros_ec_commands.h>
#include <linux/mfd/cros_ec_lpc_mec.h>
static u8 lpc_read_bytes(unsigned int offset, unsigned int length, u8 *dest)
{
int i;
int sum = 0;
for (i = 0; i < length; ++i) {
dest[i] = inb(offset + i);
sum += dest[i];
}
/* Return checksum of all bytes read */
return sum;
}
static u8 lpc_write_bytes(unsigned int offset, unsigned int length, u8 *msg)
{
int i;
int sum = 0;
for (i = 0; i < length; ++i) {
outb(msg[i], offset + i);
sum += msg[i];
}
/* Return checksum of all bytes written */
return sum;
}
#ifdef CONFIG_CROS_EC_LPC_MEC
u8 cros_ec_lpc_read_bytes(unsigned int offset, unsigned int length, u8 *dest)
{
if (length == 0)
return 0;
/* Access desired range through EMI interface */
if (offset >= MEC_EMI_RANGE_START && offset <= MEC_EMI_RANGE_END) {
/* Ensure we don't straddle EMI region */
if (WARN_ON(offset + length - 1 > MEC_EMI_RANGE_END))
return 0;
return cros_ec_lpc_io_bytes_mec(MEC_IO_READ, offset, length,
dest);
}
if (WARN_ON(offset + length > MEC_EMI_RANGE_START &&
offset < MEC_EMI_RANGE_START))
return 0;
return lpc_read_bytes(offset, length, dest);
}
u8 cros_ec_lpc_write_bytes(unsigned int offset, unsigned int length, u8 *msg)
{
if (length == 0)
return 0;
/* Access desired range through EMI interface */
if (offset >= MEC_EMI_RANGE_START && offset <= MEC_EMI_RANGE_END) {
/* Ensure we don't straddle EMI region */
if (WARN_ON(offset + length - 1 > MEC_EMI_RANGE_END))
return 0;
return cros_ec_lpc_io_bytes_mec(MEC_IO_WRITE, offset, length,
msg);
}
if (WARN_ON(offset + length > MEC_EMI_RANGE_START &&
offset < MEC_EMI_RANGE_START))
return 0;
return lpc_write_bytes(offset, length, msg);
}
void cros_ec_lpc_reg_init(void)
{
cros_ec_lpc_mec_init();
}
void cros_ec_lpc_reg_destroy(void)
{
cros_ec_lpc_mec_destroy();
}
#else /* CONFIG_CROS_EC_LPC_MEC */
u8 cros_ec_lpc_read_bytes(unsigned int offset, unsigned int length, u8 *dest)
{
return lpc_read_bytes(offset, length, dest);
}
u8 cros_ec_lpc_write_bytes(unsigned int offset, unsigned int length, u8 *msg)
{
return lpc_write_bytes(offset, length, msg);
}
void cros_ec_lpc_reg_init(void)
{
}
void cros_ec_lpc_reg_destroy(void)
{
}
#endif /* CONFIG_CROS_EC_LPC_MEC */
