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 <mranostay@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
diff --git a/drivers/iio/proximity/pulsedlight-lidar-lite-v2.c b/drivers/iio/proximity/pulsedlight-lidar-lite-v2.c
index be8ccef..e7ea44d 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 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 @@
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 @@
* 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 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 @@
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 @@
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;