On 26/11/15 17:11, Matt Ranostay wrote:
> Add an optimized i2c transfer reading function, and fallback
> to racey smbus transfers if client->adapter doesn't support this.
>
> Signed-off-by: Matt Ranostay <mranostay@xxxxxxxxx>
Few comments inline but nothing that stops me applying this.
Applied to the togreg branch of iio.git - initially pushed out as testing.
Note this branch will rebase soonish so don't base anything much on it!
Jonathan
> ---
> drivers/iio/chemical/vz89x.c | 66 ++++++++++++++++++++++++++++++++++----------
> 1 file changed, 52 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/iio/chemical/vz89x.c b/drivers/iio/chemical/vz89x.c
> index 11e59a5..c3367aa 100644
> --- a/drivers/iio/chemical/vz89x.c
> +++ b/drivers/iio/chemical/vz89x.c
> @@ -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 == VZ89X_REG_MEASUREMENT_SIZE) ? 0 : ret;
> +}
> +
> +static int vz89x_smbus_xfer(struct vz89x_data *data, u8 cmd)
> +{
> + struct i2c_client *client = data->client;
I wouldn't have bothered with the local variable, but it's just
a matter of personal taste so lets leave it be!
> + 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;
> -
THis is a random white space change that snuck in - hardly crucial but would
have been cleaner if this hadn't been in the patch.
> 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;
>
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