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iio: proximity: lidar: optimize i2c transactions

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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: Matt Ranostay <mranostay@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
This commit is contained in:
Matt Ranostay 2015-12-01 21:05:22 -08:00 committed by Jonathan Cameron
parent 8d6c16dd72
commit 366e65633c
1 changed files with 71 additions and 26 deletions
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97
drivers/iio/proximity/pulsedlight-lidar-lite-v2.c
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@ -36,8 +36,10 @@
#define LIDAR_REG_STATUS_INVALID BIT(3)
#define LIDAR_REG_STATUS_READY BIT(0)
#define LIDAR_REG_DATA_HBYTE 0x0f
#define LIDAR_REG_DATA_LBYTE 0x10
#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);
if (ret < 0) {
dev_err(&client->dev, "cannot write addr value");
return ret;
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) {
dev_err(&client->dev, "cannot read data value");
return ret;
}
*(val++) = ret;
}
ret = i2c_smbus_read_byte(client);
if (ret < 0)
dev_err(&client->dev, "cannot read data value");
return 0;
}
return ret;
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;
return ret;
}
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;