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Commit 93e87d73 authored by Matt Ranostay's avatar Matt Ranostay Committed by Jonathan Cameron
Browse files

iio: chemical: vz89x: rework i2c transfer reading 



Add an optimized i2c transfer reading function, and fallback
to racey smbus transfers if client->adapter doesn't support this.

Signed-off-by: default avatarMatt Ranostay <mranostay@gmail.com>
Signed-off-by: default avatarJonathan Cameron <jic23@kernel.org>
parent 4c3e2a40

drivers/iio/chemical/vz89x.c

+52 −14
Original line number Diff line number Diff line
@@ -34,8 +34,9 @@ 
struct vz89x_data {

	struct i2c_client *client;

	struct mutex lock;

	unsigned long last_update;

	int (*xfer)(struct vz89x_data *data, u8 cmd);



	unsigned long last_update;

	u8 buffer[VZ89X_REG_MEASUREMENT_SIZE];

};
@@ -100,27 +101,60 @@ static int vz89x_measurement_is_valid(struct vz89x_data *data) 
	return !!(data->buffer[VZ89X_REG_MEASUREMENT_SIZE - 1] > 0);

}



static int vz89x_get_measurement(struct vz89x_data *data)

static int vz89x_i2c_xfer(struct vz89x_data *data, u8 cmd)

{

	struct i2c_client *client = data->client;

	struct i2c_msg msg[2];

	int ret;

	int i;

	u8 buf[3] = { cmd, 0, 0};



	/* sensor can only be polled once a second max per datasheet */

	if (!time_after(jiffies, data->last_update + HZ))

		return 0;

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

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

	msg[0].len = 3;

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



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

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

	msg[1].len = VZ89X_REG_MEASUREMENT_SIZE;

	msg[1].buf = (char *) &data->buffer;



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



	ret = i2c_smbus_write_word_data(data->client,

					VZ89X_REG_MEASUREMENT, 0);

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

}



static int vz89x_smbus_xfer(struct vz89x_data *data, u8 cmd)

{

	struct i2c_client *client = data->client;

	int ret;

	int i;



	ret = i2c_smbus_write_word_data(client, cmd, 0);

	if (ret < 0)

		return ret;



	for (i = 0; i < VZ89X_REG_MEASUREMENT_SIZE; i++) {

		ret = i2c_smbus_read_byte(data->client);

		ret = i2c_smbus_read_byte(client);

		if (ret < 0)

			return ret;

		data->buffer[i] = ret;

	}



	return 0;

}



static int vz89x_get_measurement(struct vz89x_data *data)

{

	int ret;



	/* sensor can only be polled once a second max per datasheet */

	if (!time_after(jiffies, data->last_update + HZ))

		return 0;



	ret = data->xfer(data, VZ89X_REG_MEASUREMENT);

	if (ret < 0)

		return ret;



	ret = vz89x_measurement_is_valid(data);

	if (ret)

		return -EAGAIN;
@@ -204,15 +238,19 @@ static int vz89x_probe(struct i2c_client *client, 
	struct iio_dev *indio_dev;

	struct vz89x_data *data;



	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA |

				     I2C_FUNC_SMBUS_BYTE))

		return -ENODEV;



	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 = vz89x_i2c_xfer;

	else if (i2c_check_functionality(client->adapter,

				I2C_FUNC_SMBUS_WORD_DATA | I2C_FUNC_SMBUS_BYTE))

		data->xfer = vz89x_smbus_xfer;

	else

		return -ENOTSUPP;



	i2c_set_clientdata(client, indio_dev);

	data->client = client;

	data->last_update = jiffies - HZ;