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Commit 366e6563 authored by Matt Ranostay's avatar Matt Ranostay Committed by Jonathan Cameron
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iio: proximity: lidar: optimize i2c transactions 



Optimize device tranactions using i2c transfers versus multiple
possibly racey i2c_smbus_* function calls, and only one transaction
for distance measurement. Falls back to smbus method if i2c
functionality isn't available.

Signed-off-by: default avatarMatt Ranostay <mranostay@gmail.com>
Signed-off-by: default avatarJonathan Cameron <jic23@kernel.org>
parent 8d6c16dd

drivers/iio/proximity/pulsedlight-lidar-lite-v2.c

+70 −25
Original line number Diff line number Diff line
@@ -38,6 +38,8 @@ 


#define LIDAR_REG_DATA_HBYTE		0x0f

#define LIDAR_REG_DATA_LBYTE		0x10

#define LIDAR_REG_DATA_WORD_READ	BIT(7)



#define LIDAR_REG_PWR_CONTROL	0x65



#define LIDAR_DRV_NAME "lidar"
@@ -46,6 +48,9 @@ struct lidar_data { 
	struct iio_dev *indio_dev;

	struct i2c_client *client;



	int (*xfer)(struct lidar_data *data, u8 reg, u8 *val, int len);

	int i2c_enabled;



	u16 buffer[8]; /* 2 byte distance + 8 byte timestamp */

};
@@ -64,7 +69,28 @@ static const struct iio_chan_spec lidar_channels[] = { 
	IIO_CHAN_SOFT_TIMESTAMP(1),

};



static int lidar_read_byte(struct lidar_data *data, int reg)

static int lidar_i2c_xfer(struct lidar_data *data, u8 reg, u8 *val, int len)

{

	struct i2c_client *client = data->client;

	struct i2c_msg msg[2];

	int ret;



	msg[0].addr = client->addr;

	msg[0].flags = client->flags | I2C_M_STOP;

	msg[0].len = 1;

	msg[0].buf  = (char *) &reg;



	msg[1].addr = client->addr;

	msg[1].flags = client->flags | I2C_M_RD;

	msg[1].len = len;

	msg[1].buf = (char *) val;



	ret = i2c_transfer(client->adapter, msg, 2);



	return (ret == 2) ? 0 : ret;

}



static int lidar_smbus_xfer(struct lidar_data *data, u8 reg, u8 *val, int len)

{

	struct i2c_client *client = data->client;

	int ret;
@@ -74,17 +100,35 @@ static int lidar_read_byte(struct lidar_data *data, int reg) 
	 * so in turn i2c_smbus_read_byte_data cannot be used

	 */



	ret = i2c_smbus_write_byte(client, reg);

	while (len--) {

		ret = i2c_smbus_write_byte(client, reg++);

		if (ret < 0) {

			dev_err(&client->dev, "cannot write addr value");

			return ret;

		}



		ret = i2c_smbus_read_byte(client);

	if (ret < 0)

		if (ret < 0) {

			dev_err(&client->dev, "cannot read data value");

			return ret;

		}



		*(val++) = ret;

	}



	return 0;

}



static int lidar_read_byte(struct lidar_data *data, u8 reg)

{

	int ret;

	u8 val;



	ret = data->xfer(data, reg, &val, 1);

	if (ret < 0)

		return ret;



	return val;

}



static inline int lidar_write_control(struct lidar_data *data, int val)
@@ -100,22 +144,14 @@ static inline int lidar_write_power(struct lidar_data *data, int val) 


static int lidar_read_measurement(struct lidar_data *data, u16 *reg)

{

	int ret;

	int val;

	int ret = data->xfer(data, LIDAR_REG_DATA_HBYTE |

			(data->i2c_enabled ? LIDAR_REG_DATA_WORD_READ : 0),

			(u8 *) reg, 2);



	ret = lidar_read_byte(data, LIDAR_REG_DATA_HBYTE);

	if (ret < 0)

		return ret;

	val = ret << 8;

	if (!ret)

		*reg = be16_to_cpu(*reg);



	ret = lidar_read_byte(data, LIDAR_REG_DATA_LBYTE);

	if (ret < 0)

	return ret;



	val |= ret;

	*reg = val;



	return 0;

}



static int lidar_get_measurement(struct lidar_data *data, u16 *reg)
@@ -233,6 +269,16 @@ static int lidar_probe(struct i2c_client *client, 
	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));

	if (!indio_dev)

		return -ENOMEM;

	data = iio_priv(indio_dev);



	if (i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {

		data->xfer = lidar_i2c_xfer;

		data->i2c_enabled = 1;

	} else if (i2c_check_functionality(client->adapter,

				I2C_FUNC_SMBUS_WORD_DATA | I2C_FUNC_SMBUS_BYTE))

		data->xfer = lidar_smbus_xfer;

	else

		return -ENOTSUPP;



	indio_dev->info = &lidar_info;

	indio_dev->name = LIDAR_DRV_NAME;
@@ -240,7 +286,6 @@ static int lidar_probe(struct i2c_client *client, 
	indio_dev->num_channels = ARRAY_SIZE(lidar_channels);

	indio_dev->modes = INDIO_DIRECT_MODE;



	data = iio_priv(indio_dev);

	i2c_set_clientdata(client, indio_dev);



	data->client = client;