driver/accel_bma2x2.c

/* Copyright 2015 The Chromium OS Authors. All rights reserved.
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

/*
 * Bosch Accelerometer driver for Chrome EC
 *
 * Supported: BMA255
 */

#include "accelgyro.h"
#include "common.h"
#include "console.h"
#include "driver/accel_bma2x2.h"
#include "i2c.h"
#include "math_util.h"
#include "spi.h"
#include "task.h"
#include "util.h"

#define CPUTS(outstr) cputs(CC_ACCEL, outstr)
#define CPRINTF(format, args...) cprintf(CC_ACCEL, format, ## args)

/* Number of times to attempt to enable sensor before giving up. */
#define SENSOR_ENABLE_ATTEMPTS 5

/*
 * Struct for pairing an engineering value with the register value for a
 * parameter.
 */
struct accel_param_pair {
	int val; /* Value in engineering units. */
	int reg; /* Corresponding register value. */
};

/* List of range values in +/-G's and their associated register values. */
static const struct accel_param_pair ranges[] = {
	{2, BMA2x2_RANGE_2G},
	{4, BMA2x2_RANGE_4G},
	{8, BMA2x2_RANGE_8G},
	{16, BMA2x2_RANGE_16G},
};

/* List of ODR values in mHz and their associated register values. */
static const struct accel_param_pair datarates[] = {
	{781,     BMA2x2_BW_7_81HZ},
	{1563,    BMA2x2_BW_15_63HZ},
	{3125,    BMA2x2_BW_31_25HZ},
	{6250,    BMA2x2_BW_62_50HZ},
	{12500,   BMA2x2_BW_125HZ},
	{25000,   BMA2x2_BW_250HZ},
	{50000,   BMA2x2_BW_500HZ},
	{100000,  BMA2x2_BW_1000HZ},
};

/**
 * Find index into a accel_param_pair that matches the given engineering value
 * passed in. The round_up flag is used to specify whether to round up or down.
 * Note, this function always returns a valid index. If the request is
 * outside the range of values, it returns the closest valid index.
 */
static int find_param_index(const int eng_val, const int round_up,
			const struct accel_param_pair *pairs,
			const int size)
{
	int i = 0;

	/* match first index */
	if (eng_val <= pairs[i].val)
		return i;

	/* Linear search for index to match. */
	while (++i < size) {
		if (eng_val < pairs[i].val)
			return round_up ? i : i - 1;
		else if (eng_val == pairs[i].val)
			return i;
	}

	return i - 1;
}

/**
 * Read register from accelerometer.
 */
static int raw_read8(const int port, const int addr, const int reg,
					 int *data_ptr)
{
	return i2c_read8(port, addr, reg, data_ptr);
}

/**
 * Write register from accelerometer.
 */
static int raw_write8(const int port, const int addr, const int reg, int data)
{
	return i2c_write8(port, addr, reg, data);
}

static int raw_read_multi(const int port, int addr, uint8_t reg,
			  uint8_t *rxdata, int rxlen)
{
	int rv;

	i2c_lock(port, 1);
	rv = i2c_xfer(port, addr, &reg, 1, rxdata, rxlen,
		      I2C_XFER_SINGLE);
	i2c_lock(port, 0);

	return rv;
}

static int set_range(const struct motion_sensor_t *s, int range, int rnd)
{
	int ret,  index, reg, range_val, reg_val, range_reg_val;
	struct bma2x2_accel_data *data = s->drv_data;

	/* Find index for interface pair matching the specified range. */
	index = find_param_index(range, rnd, ranges, ARRAY_SIZE(ranges));

	reg = BMA2x2_RANGE_SELECT_REG;
	range_val = ranges[index].reg;

	mutex_lock(s->mutex);

	/* Determine the new value of control reg and attempt to write it. */
	ret = raw_read8(s->port, s->addr, reg, &range_reg_val);
	if (ret != EC_SUCCESS) {
		mutex_unlock(s->mutex);
		return ret;
	}
	reg_val = (range_reg_val & ~BMA2x2_RANGE_SELECT_MSK) | range_val;
	ret = raw_write8(s->port, s->addr, reg, reg_val);

	/* If successfully written, then save the range. */
	if (ret == EC_SUCCESS)
		data->sensor_range = index;

	mutex_unlock(s->mutex);

	return ret;
}

static int get_range(const struct motion_sensor_t *s)
{
	struct bma2x2_accel_data *data = s->drv_data;

	return ranges[data->sensor_range].val;
}

static int set_resolution(const struct motion_sensor_t *s, int res, int rnd)
{
	/* Only one resolution, BMA2x2_RESOLUTION, so nothing to do. */
	return EC_SUCCESS;
}

static int get_resolution(const struct motion_sensor_t *s)
{
	return BMA2x2_RESOLUTION;
}

static int set_data_rate(const struct motion_sensor_t *s, int rate, int rnd)
{
	int ret, index, odr_val, odr_reg_val, reg_val, reg;
	struct bma2x2_accel_data *data = s->drv_data;

	/* Find index for interface pair matching the specified rate. */
	index = find_param_index(rate, rnd, datarates, ARRAY_SIZE(datarates));

	odr_val = datarates[index].reg;
	reg = BMA2x2_BW_REG;

	mutex_lock(s->mutex);

	/* Determine the new value of control reg and attempt to write it. */
	ret = raw_read8(s->port, s->addr, reg, &odr_reg_val);
	if (ret != EC_SUCCESS) {
		mutex_unlock(s->mutex);
		return ret;
	}
	reg_val = (odr_reg_val & ~BMA2x2_BW_MSK) | odr_val;
	/* Set output data rate. */
	ret = raw_write8(s->port, s->addr, reg, reg_val);

	/* If successfully written, then save the new data rate. */
	if (ret == EC_SUCCESS)
		data->sensor_datarate = index;

	mutex_unlock(s->mutex);
	return ret;
}

static int get_data_rate(const struct motion_sensor_t *s)
{
	struct bma2x2_accel_data *data = s->drv_data;

	return datarates[data->sensor_datarate].val;
}

static int set_offset(const struct motion_sensor_t *s, const int16_t *offset,
		      int16_t temp)
{
	/* temperature is ignored */
	struct bma2x2_accel_data *data = s->drv_data;

	data->offset[X] = offset[X];
	data->offset[Y] = offset[Y];
	data->offset[Z] = offset[Z];

	return EC_SUCCESS;
}

static int get_offset(const struct motion_sensor_t *s, int16_t *offset,
		      int16_t *temp)
{
	struct bma2x2_accel_data *data = s->drv_data;

	offset[X] = data->offset[X];
	offset[Y] = data->offset[Y];
	offset[Z] = data->offset[Z];
	*temp = EC_MOTION_SENSE_INVALID_CALIB_TEMP;

	return EC_SUCCESS;
}

static int read(const struct motion_sensor_t *s, vector_3_t v)
{
	uint8_t acc[6];
	int ret, i, range;
	struct bma2x2_accel_data *data = s->drv_data;

	/* Read 6 bytes starting at X_AXIS_LSB. */
	mutex_lock(s->mutex);
	ret = raw_read_multi(s->port, s->addr, BMA2x2_X_AXIS_LSB_ADDR, acc, 6);
	mutex_unlock(s->mutex);

	if (ret != EC_SUCCESS)
		return ret;

	/*
	 * Convert acceleration to a signed 16-bit number. Note, based on
	 * the order of the registers:
	 *
	 * acc[0] = X_AXIS_LSB -> bit 7~4 for value, bit 0 for new data bit
	 * acc[1] = X_AXIS_MSB
	 * acc[2] = Y_AXIS_LSB -> bit 7~4 for value, bit 0 for new data bit
	 * acc[3] = Y_AXIS_MSB
	 * acc[4] = Z_AXIS_LSB -> bit 7~4 for value, bit 0 for new data bit
	 * acc[5] = Z_AXIS_MSB
	 *
	 * Add calibration offset before returning the data.
	 */
	for (i = X; i <= Z; i++)
		v[i] = (((int8_t)acc[i * 2 + 1]) << 8) | (acc[i * 2] & 0xf0);
	rotate(v, *s->rot_standard_ref, v);

	/* apply offset in the device coordinates */
	range = get_range(s);
	for (i = X; i <= Z; i++)
		v[i] += (data->offset[i] << 5) / range;

	return EC_SUCCESS;
}

static int init(const struct motion_sensor_t *s)
{
	int ret = 0, tries = 0, val, reg, reset_field;

	ret = raw_read8(s->port, s->addr, BMA2x2_CHIP_ID_ADDR, &val);
	if (ret)
		return EC_ERROR_UNKNOWN;

	if (val != BMA255_CHIP_ID_MAJOR)
		return EC_ERROR_ACCESS_DENIED;

	/* Reset the chip to be in a good state */
	reg = BMA2x2_RST_ADDR;
	reset_field = BMA2x2_CMD_SOFT_RESET;

	mutex_lock(s->mutex);

	ret = raw_read8(s->port, s->addr, reg, &val);
	if (ret != EC_SUCCESS) {
		mutex_unlock(s->mutex);
		return ret;
	}
	val |= reset_field;
	ret = raw_write8(s->port, s->addr, reg, val);
	if (ret != EC_SUCCESS) {
		mutex_unlock(s->mutex);
		return ret;
	}

	/* The SRST will be cleared when reset is complete. */
	do {
		ret = raw_read8(s->port, s->addr, reg, &val);

		/* Reset complete. */
		if ((ret == EC_SUCCESS) && !(val & reset_field))
			break;

		/* Check for tires. */
		if (tries++ > SENSOR_ENABLE_ATTEMPTS) {
			ret = EC_ERROR_TIMEOUT;
			mutex_unlock(s->mutex);
			return ret;
		}
		msleep(1);
	} while (1);
	mutex_unlock(s->mutex);

	/* Initialize with the desired parameters. */
	ret = set_range(s, s->default_range, 1);
	if (ret != EC_SUCCESS)
		return ret;

	ret = set_resolution(s, 12, 1);
	if (ret != EC_SUCCESS)
		return ret;

	sensor_init_done(s, get_range(s));

	return ret;
}

const struct accelgyro_drv bma2x2_accel_drv = {
	.init = init,
	.read = read,
	.set_range = set_range,
	.get_range = get_range,
	.set_resolution = set_resolution,
	.get_resolution = get_resolution,
	.set_data_rate = set_data_rate,
	.get_data_rate = get_data_rate,
	.set_offset = set_offset,
	.get_offset = get_offset,
	.perform_calib = NULL,
};