staging: iio: tsl2583: i2c_smbus_write_byte() / i2c_smbus_read_byte() migration

There were several places where the driver would first call
i2c_smbus_write_byte() to select the register on the device, and then
call i2c_smbus_read_byte() to get the contents of that register. The
code would look roughly like:

/* Select register */
i2c_smbus_write_byte(client, REGISTER);

/* Read the the last register that was written to */
int data = i2c_smbus_read_byte(client);

Rewrite this to use i2c_smbus_read_byte_data() to combine the two
calls into one:

int data = i2c_smbus_read_byte_data(chip->client, REGISTER);

Verified that the driver still functions correctly using a TSL2581
hooked up to a Raspberry Pi 2.

This fixes the following warnings that were found by the
kbuild test robot that were introduced by commit 8ba355cce3c6 ("staging:
iio: tsl2583: check for error code from i2c_smbus_read_byte()").

drivers/staging/iio/light/tsl2583.c:365:5-12: WARNING: Unsigned
expression compared with zero: reg_val < 0

drivers/staging/iio/light/tsl2583.c:388:5-12: WARNING: Unsigned
expression compared with zero: reg_val < 0

This also removes the need for the taos_i2c_read() function since all
callers were only calling the function with a length of 1.

Signed-off-by: Brian Masney <masneyb@onstation.org>
Cc: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

diff --git a/drivers/staging/iio/light/tsl2583.c b/drivers/staging/iio/light/tsl2583.c
index 49b19f5..a3a9095 100644 (file)
--- a/drivers/staging/iio/light/tsl2583.c
+++ b/drivers/staging/iio/light/tsl2583.c
@@ -155,39 +155,6 @@ static void taos_defaults(struct tsl2583_chip *chip)
 }
 
 /*
- * Read a number of bytes starting at register (reg) location.
- * Return 0, or i2c_smbus_write_byte ERROR code.
- */
-static int
-taos_i2c_read(struct i2c_client *client, u8 reg, u8 *val, unsigned int len)
-{
-       int i, ret;
-
-       for (i = 0; i < len; i++) {
-               /* select register to write */
-               ret = i2c_smbus_write_byte(client, (TSL258X_CMD_REG | reg));
-               if (ret < 0) {
-                       dev_err(&client->dev,
-                               "taos_i2c_read failed to write register %x\n",
-                               reg);
-                       return ret;
-               }
-               /* read the data */
-               ret = i2c_smbus_read_byte(client);
-               if (ret < 0) {
-                       dev_err(&client->dev,
-                               "%s failed to read byte after writing to register %x\n",
-                               __func__, reg);
-                       return ret;
-               }
-               *val = ret;
-               val++;
-               reg++;
-       }
-       return 0;
-}
-
-/*
  * Reads and calculates current lux value.
  * The raw ch0 and ch1 values of the ambient light sensed in the last
  * integration cycle are read from the device.
@@ -220,13 +187,14 @@ static int taos_get_lux(struct iio_dev *indio_dev)
                goto done;
        }
 
-       ret = taos_i2c_read(chip->client, (TSL258X_CMD_REG), &buf[0], 1);
+       ret = i2c_smbus_read_byte_data(chip->client, TSL258X_CMD_REG);
        if (ret < 0) {
                dev_err(&chip->client->dev, "taos_get_lux failed to read CMD_REG\n");
                goto done;
        }
+
        /* is data new & valid */
-       if (!(buf[0] & TSL258X_STA_ADC_INTR)) {
+       if (!(ret & TSL258X_STA_ADC_INTR)) {
                dev_err(&chip->client->dev, "taos_get_lux data not valid\n");
                ret = chip->als_cur_info.lux; /* return LAST VALUE */
                goto done;
@@ -235,13 +203,14 @@ static int taos_get_lux(struct iio_dev *indio_dev)
        for (i = 0; i < 4; i++) {
                int reg = TSL258X_CMD_REG | (TSL258X_ALS_CHAN0LO + i);
 
-               ret = taos_i2c_read(chip->client, reg, &buf[i], 1);
+               ret = i2c_smbus_read_byte_data(chip->client, reg);
                if (ret < 0) {
                        dev_err(&chip->client->dev,
                                "taos_get_lux failed to read register %x\n",
                                reg);
                        goto done;
                }
+               buf[i] = ret;
        }
 
        /*
@@ -343,52 +312,36 @@ done:
 static int taos_als_calibrate(struct iio_dev *indio_dev)
 {
        struct tsl2583_chip *chip = iio_priv(indio_dev);
-       u8 reg_val;
        unsigned int gain_trim_val;
        int ret;
        int lux_val;
 
-       ret = i2c_smbus_write_byte(chip->client,
-                                  (TSL258X_CMD_REG | TSL258X_CNTRL));
+       ret = i2c_smbus_read_byte_data(chip->client,
+                                      TSL258X_CMD_REG | TSL258X_CNTRL);
        if (ret < 0) {
                dev_err(&chip->client->dev,
-                       "taos_als_calibrate failed to reach the CNTRL register, ret=%d\n",
-                       ret);
-               return ret;
-       }
-
-       reg_val = i2c_smbus_read_byte(chip->client);
-       if (reg_val < 0) {
-               dev_err(&chip->client->dev,
-                       "%s failed to read after writing to the CNTRL register\n",
+                       "%s failed to read from the CNTRL register\n",
                        __func__);
                return ret;
        }
 
-       if ((reg_val & (TSL258X_CNTL_ADC_ENBL | TSL258X_CNTL_PWR_ON))
+       if ((ret & (TSL258X_CNTL_ADC_ENBL | TSL258X_CNTL_PWR_ON))
                        != (TSL258X_CNTL_ADC_ENBL | TSL258X_CNTL_PWR_ON)) {
                dev_err(&chip->client->dev,
                        "taos_als_calibrate failed: device not powered on with ADC enabled\n");
                return -EINVAL;
        }
 
-       ret = i2c_smbus_write_byte(chip->client,
-                                  (TSL258X_CMD_REG | TSL258X_CNTRL));
+       ret = i2c_smbus_read_byte_data(chip->client,
+                                      TSL258X_CMD_REG | TSL258X_CNTRL);
        if (ret < 0) {
                dev_err(&chip->client->dev,
-                       "taos_als_calibrate failed to reach the STATUS register, ret=%d\n",
-                       ret);
-               return ret;
-       }
-       reg_val = i2c_smbus_read_byte(chip->client);
-       if (reg_val < 0) {
-               dev_err(&chip->client->dev,
-                       "%s failed to read after writing to the STATUS register\n",
+                       "%s failed to read from the CNTRL register\n",
                        __func__);
                return ret;
        }
 
-       if ((reg_val & TSL258X_STA_ADC_VALID) != TSL258X_STA_ADC_VALID) {
+       if ((ret & TSL258X_STA_ADC_VALID) != TSL258X_STA_ADC_VALID) {
                dev_err(&chip->client->dev,
                        "taos_als_calibrate failed: STATUS - ADC not valid.\n");
                return -ENODATA;
@@ -847,15 +800,9 @@ static int taos_probe(struct i2c_client *clientp,
        memcpy(chip->taos_config, taos_config, sizeof(chip->taos_config));
 
        for (i = 0; i < TSL258X_MAX_DEVICE_REGS; i++) {
-               ret = i2c_smbus_write_byte(clientp,
-                               (TSL258X_CMD_REG | (TSL258X_CNTRL + i)));
-               if (ret < 0) {
-                       dev_err(&clientp->dev,
-                               "i2c_smbus_write_byte to cmd reg failed in taos_probe(), err = %d\n",
-                               ret);
-                       return ret;
-               }
-               ret = i2c_smbus_read_byte(clientp);
+               ret = i2c_smbus_read_byte_data(clientp,
+                                              (TSL258X_CMD_REG |
+                                               (TSL258X_CNTRL + i)));
                if (ret < 0) {
                        dev_err(&clientp->dev,
                                "i2c_smbus_read_byte from reg failed in taos_probe(), err = %d\n",