cros_ec_spi.c
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/*
* Chromium OS cros_ec driver - SPI interface
*
* Copyright (c) 2012 The Chromium OS Authors.
*
* SPDX-License-Identifier: GPL-2.0+
*/
/*
* The Matrix Keyboard Protocol driver handles talking to the keyboard
* controller chip. Mostly this is for keyboard functions, but some other
* things have slipped in, so we provide generic services to talk to the
* KBC.
*/
#include <common.h>
#include <cros_ec.h>
#include <spi.h>
/**
* Send a command to a LPC CROS_EC device and return the reply.
*
* The device's internal input/output buffers are used.
*
* @param dev CROS_EC device
* @param cmd Command to send (EC_CMD_...)
* @param cmd_version Version of command to send (EC_VER_...)
* @param dout Output data (may be NULL If dout_len=0)
* @param dout_len Size of output data in bytes
* @param dinp Returns pointer to response data. This will be
* untouched unless we return a value > 0.
* @param din_len Maximum size of response in bytes
* @return number of bytes in response, or -1 on error
*/
int cros_ec_spi_command(struct cros_ec_dev *dev, uint8_t cmd, int cmd_version,
const uint8_t *dout, int dout_len,
uint8_t **dinp, int din_len)
{
int in_bytes = din_len + 4; /* status, length, checksum, trailer */
uint8_t *out;
uint8_t *p;
int csum, len;
int rv;
/*
* Sanity-check input size to make sure it plus transaction overhead
* fits in the internal device buffer.
*/
if (in_bytes > sizeof(dev->din)) {
debug("%s: Cannot receive %d bytes\n", __func__, din_len);
return -1;
}
/* We represent message length as a byte */
if (dout_len > 0xff) {
debug("%s: Cannot send %d bytes\n", __func__, dout_len);
return -1;
}
/*
* Clear input buffer so we don't get false hits for MSG_HEADER
*/
memset(dev->din, '\0', in_bytes);
if (spi_claim_bus(dev->spi)) {
debug("%s: Cannot claim SPI bus\n", __func__);
return -1;
}
out = dev->dout;
out[0] = cmd_version;
out[1] = cmd;
out[2] = (uint8_t)dout_len;
memcpy(out + 3, dout, dout_len);
csum = cros_ec_calc_checksum(out, 3)
+ cros_ec_calc_checksum(dout, dout_len);
out[3 + dout_len] = (uint8_t)csum;
/*
* Send output data and receive input data starting such that the
* message body will be dword aligned.
*/
p = dev->din + sizeof(int64_t) - 2;
len = dout_len + 4;
cros_ec_dump_data("out", cmd, out, len);
rv = spi_xfer(dev->spi, max(len, in_bytes) * 8, out, p,
SPI_XFER_BEGIN | SPI_XFER_END);
spi_release_bus(dev->spi);
if (rv) {
debug("%s: Cannot complete SPI transfer\n", __func__);
return -1;
}
len = min(p[1], din_len);
cros_ec_dump_data("in", -1, p, len + 3);
/* Response code is first byte of message */
if (p[0] != EC_RES_SUCCESS) {
printf("%s: Returned status %d\n", __func__, p[0]);
return -(int)(p[0]);
}
/* Check checksum */
csum = cros_ec_calc_checksum(p, len + 2);
if (csum != p[len + 2]) {
debug("%s: Invalid checksum rx %#02x, calced %#02x\n", __func__,
p[2 + len], csum);
return -1;
}
/* Anything else is the response data */
*dinp = p + 2;
return len;
}
int cros_ec_spi_decode_fdt(struct cros_ec_dev *dev, const void *blob)
{
/* Decode interface-specific FDT params */
dev->max_frequency = fdtdec_get_int(blob, dev->node,
"spi-max-frequency", 500000);
dev->cs = fdtdec_get_int(blob, dev->node, "reg", 0);
return 0;
}
/**
* Initialize SPI protocol.
*
* @param dev CROS_EC device
* @param blob Device tree blob
* @return 0 if ok, -1 on error
*/
int cros_ec_spi_init(struct cros_ec_dev *dev, const void *blob)
{
dev->spi = spi_setup_slave_fdt(blob, dev->parent_node, dev->node);
if (!dev->spi) {
debug("%s: Could not setup SPI slave\n", __func__);
return -1;
}
return 0;
}