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: Matt Ranostay <mranostay@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
diff --git a/drivers/iio/chemical/vz89x.c b/drivers/iio/chemical/vz89x.c
index 11e59a5..b8b8049 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 @@
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 @@
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;