// 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"
#define ACPI_LOCK_DELAY_MS 500
/*
* 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 DEFINE_MUTEX(io_mutex);
/*
* An alternative mutex to be used when the ACPI AML code may also
* access memmap data. When set, this mutex is used in preference to
* io_mutex.
*/
static acpi_handle aml_mutex;
static u16 mec_emi_base, mec_emi_end;
/**
* cros_ec_lpc_mec_lock() - Acquire mutex for EMI
*
* @return: Negative error code, or zero for success
*/
static int cros_ec_lpc_mec_lock(void)
{
bool success;
if (!aml_mutex) {
mutex_lock(&io_mutex);
return 0;
}
success = ACPI_SUCCESS(acpi_acquire_mutex(aml_mutex,
NULL, ACPI_LOCK_DELAY_MS));
if (!success)
return -EBUSY;
return 0;
}
/**
* cros_ec_lpc_mec_unlock() - Release mutex for EMI
*
* @return: Negative error code, or zero for success
*/
static int cros_ec_lpc_mec_unlock(void)
{
bool success;
if (!aml_mutex) {
mutex_unlock(&io_mutex);
return 0;
}
success = ACPI_SUCCESS(acpi_release_mutex(aml_mutex, NULL));
if (!success)
return -EBUSY;
return 0;
}
/**
* 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 (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: A negative error code on error, or 8-bit checksum of all
* bytes read / written
*/
int 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;
int ret;
if (length == 0)
return 0;
/* 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;
ret = cros_ec_lpc_mec_lock();
if (ret)
return ret;
/* 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:
ret = cros_ec_lpc_mec_unlock();
if (ret)
return ret;
return sum;
}
EXPORT_SYMBOL(cros_ec_lpc_io_bytes_mec);
void cros_ec_lpc_mec_init(unsigned int base, unsigned int end)
{
mec_emi_base = base;
mec_emi_end = end;
}
EXPORT_SYMBOL(cros_ec_lpc_mec_init);
int cros_ec_lpc_mec_acpi_mutex(struct acpi_device *adev, const char *pathname)
{
int status;
if (!adev)
return -ENOENT;
status = acpi_get_handle(adev->handle, pathname, &aml_mutex);
if (ACPI_FAILURE(status))
return -ENOENT;
return 0;
}
EXPORT_SYMBOL(cros_ec_lpc_mec_acpi_mutex);
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