From 366e65633cf4f117609965cd6e189f2cd11533d2 Mon Sep 17 00:00:00 2001 From: Matt Ranostay Date: Tue, 1 Dec 2015 21:05:22 -0800 Subject: [PATCH] iio: proximity: lidar: optimize i2c transactions 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 Signed-off-by: Jonathan Cameron --- .../iio/proximity/pulsedlight-lidar-lite-v2.c | 95 ++++++++++++++----- 1 file changed, 70 insertions(+), 25 deletions(-) diff --git a/drivers/iio/proximity/pulsedlight-lidar-lite-v2.c b/drivers/iio/proximity/pulsedlight-lidar-lite-v2.c index be8ccef735f8..e7ea44d61942 100644 --- a/drivers/iio/proximity/pulsedlight-lidar-lite-v2.c +++ b/drivers/iio/proximity/pulsedlight-lidar-lite-v2.c @@ -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 *) ® + + 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); + return 0; +} + +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) - dev_err(&client->dev, "cannot read data value"); + return ret; - 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; - - ret = lidar_read_byte(data, LIDAR_REG_DATA_HBYTE); - if (ret < 0) - return ret; - val = ret << 8; + 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_LBYTE); - if (ret < 0) - return ret; + if (!ret) + *reg = be16_to_cpu(*reg); - 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; -- 2.30.2