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iio: chemical: vz89x: rework i2c transfer reading

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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@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
This commit is contained in:
Matt Ranostay 2015-12-01 21:47:20 -08:00 committed by Jonathan Cameron
parent 4c3e2a4036
commit 93e87d73cc
1 changed files with 54 additions and 16 deletions
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70
drivers/iio/chemical/vz89x.c
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@ -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_i2c_xfer(struct vz89x_data *data, u8 cmd)
{
struct i2c_client *client = data->client;
struct i2c_msg msg[2];
int ret;
u8 buf[3] = { cmd, 0, 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);
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(client);
if (ret < 0)
return ret;
data->buffer[i] = ret;
}
return 0;
}
static int vz89x_get_measurement(struct vz89x_data *data)
{
int ret;
int i;
/* sensor can only be polled once a second max per datasheet */
if (!time_after(jiffies, data->last_update + HZ))
return 0;
ret = i2c_smbus_write_word_data(data->client,
VZ89X_REG_MEASUREMENT, 0);
ret = data->xfer(data, VZ89X_REG_MEASUREMENT);
if (ret < 0)
return ret;
for (i = 0; i < VZ89X_REG_MEASUREMENT_SIZE; i++) {
ret = i2c_smbus_read_byte(data->client);
if (ret < 0)
return ret;
data->buffer[i] = 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;