staging:iio:adc:ad7152: Miscellaneous fixes and touch-up

Remove unused define.
Introduce cached SETUP variables.
Wait until calibration finished. (Device returns to idle state)
IIO_CHAN_INFO_CALIBSCALE_SEPARATE use proper scales. (range 1.0 to 1.99999)
i2c_smbus word transactions expect low byte first, therefore swap bytes.
CAPDIFF is bit in SETUP not CFG.
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/iio/adc/ad7152.c

@@ -52,6 +52,7 @@
 #define AD7152_SETUP_RANGE_0_5pF	(1 << 6)
 #define AD7152_SETUP_RANGE_1pF		(2 << 6)
 #define AD7152_SETUP_RANGE_4pF		(3 << 6)
+#define AD7152_SETUP_RANGE(x)		((x) << 6)
 
 /* Config Register Bit Designations (AD7152_REG_CFG) */
 #define AD7152_CONF_CH2EN		(1 << 3)
@@ -66,8 +67,6 @@
 #define AD7152_CAPDAC_DACEN		(1 << 7)
 #define AD7152_CAPDAC_DACP(x)		((x) & 0x1F)
 
-#define AD7152_MAX_CONV_MODE		6
-
 enum {
 	AD7152_DATA,
 	AD7152_OFFS,
@@ -86,6 +85,7 @@ struct ad7152_chip_info {
 	 * conversion time/update rate setup per channel
 	 */
 	u8	filter_rate_setup;
+	u8	setup[2];
 };
 
 static inline ssize_t ad7152_start_calib(struct device *dev,
@@ -98,7 +98,7 @@ static inline ssize_t ad7152_start_calib(struct device *dev,
 	struct ad7152_chip_info *chip = iio_priv(dev_info);
 	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 	bool doit;
-	int ret;
+	int ret, timeout = 10;
 
 	ret = strtobool(buf, &doit);
 	if (ret < 0)
@@ -115,8 +115,14 @@ static inline ssize_t ad7152_start_calib(struct device *dev,
 	ret = i2c_smbus_write_byte_data(chip->client, AD7152_REG_CFG, regval);
 	if (ret < 0)
 		return ret;
-	/* Unclear on period this should be set for or whether it flips back
-	 * to idle automatically */
+
+	do {
+		mdelay(20);
+		ret = i2c_smbus_read_byte_data(chip->client, AD7152_REG_CFG);
+		if (ret < 0)
+			return ret;
+	} while ((ret == regval) && timeout--);
+
 	return len;
 }
 static ssize_t ad7152_start_offset_calib(struct device *dev,
@@ -124,7 +130,6 @@ static ssize_t ad7152_start_offset_calib(struct device *dev,
 					 const char *buf,
 					 size_t len)
 {
-
 	return ad7152_start_calib(dev, attr, buf, len,
 				  AD7152_CONF_MODE_OFFS_CAL);
 }
@@ -222,11 +227,14 @@ static int ad7152_write_raw(struct iio_dev *dev_info,
 
 	switch (mask) {
 	case (1 << IIO_CHAN_INFO_CALIBSCALE_SEPARATE):
-		if ((val < 0) | (val > 0xFFFF))
+		if (val != 1)
 			return -EINVAL;
+
+		val = (val2 * 1024) / 15625;
+
 		ret = i2c_smbus_write_word_data(chip->client,
 				ad7152_addresses[chan->channel][AD7152_GAIN],
-				val);
+				swab16(val));
 		if (ret < 0)
 			return ret;
 
@@ -237,7 +245,7 @@ static int ad7152_write_raw(struct iio_dev *dev_info,
 			return -EINVAL;
 		ret = i2c_smbus_write_word_data(chip->client,
 				ad7152_addresses[chan->channel][AD7152_OFFS],
-				val);
+				swab16(val));
 		if (ret < 0)
 			return ret;
 
@@ -248,14 +256,13 @@ static int ad7152_write_raw(struct iio_dev *dev_info,
 		for (i = 0; i < ARRAY_SIZE(ad7152_scale_table); i++)
 			if (val2 <= ad7152_scale_table[i])
 				break;
-		ret = i2c_smbus_read_byte_data(chip->client,
-				ad7152_addresses[chan->channel][AD7152_SETUP]);
-		if (ret < 0)
-			return ret;
-		if ((ret & 0xC0) != i)
+
+		chip->setup[chan->channel] &= ~AD7152_SETUP_RANGE_4pF;
+		chip->setup[chan->channel] |= AD7152_SETUP_RANGE(i);
+
 		ret = i2c_smbus_write_byte_data(chip->client,
 				ad7152_addresses[chan->channel][AD7152_SETUP],
-				(ret & ~0xC0) | i);
+				chip->setup[chan->channel]);
 		if (ret < 0)
 			return ret;
 		else
@@ -275,18 +282,30 @@ static int ad7152_read_raw(struct iio_dev *dev_info,
 	switch (mask) {
 	case 0:
 		/* First set whether in differential mode */
+
+		regval = chip->setup[chan->channel];
+
 		if (chan->differential)
-			regval = AD7152_SETUP_CAPDIFF;
+			chip->setup[chan->channel] |= AD7152_SETUP_CAPDIFF;
+		else
+			chip->setup[chan->channel] &= ~AD7152_SETUP_CAPDIFF;
 
+		if (regval != chip->setup[chan->channel]) {
+			ret = i2c_smbus_write_byte_data(chip->client,
+				ad7152_addresses[chan->channel][AD7152_SETUP],
+				chip->setup[chan->channel]);
+			if (ret < 0)
+				return ret;
+		}
 		/* Make sure the channel is enabled */
-		if (chan->address == 0)
-			regval |= AD7152_CONF_CH1EN;
+		if (chan->channel == 0)
+			regval = AD7152_CONF_CH1EN;
 		else
-			regval |= AD7152_CONF_CH2EN;
+			regval = AD7152_CONF_CH2EN;
+
 		/* Trigger a single read */
 		regval |= AD7152_CONF_MODE_SINGLE_CONV;
-		ret = i2c_smbus_write_byte_data(chip->client,
-				ad7152_addresses[chan->channel][AD7152_SETUP],
+		ret = i2c_smbus_write_byte_data(chip->client, AD7152_REG_CFG,
 				regval);
 		if (ret < 0)
 			return ret;
@@ -297,24 +316,26 @@ static int ad7152_read_raw(struct iio_dev *dev_info,
 				ad7152_addresses[chan->channel][AD7152_DATA]);
 		if (ret < 0)
 			return ret;
-		*val = ret;
+		*val = swab16(ret);
 
 		return IIO_VAL_INT;
 	case (1 << IIO_CHAN_INFO_CALIBSCALE_SEPARATE):
-		/* FIXME: Hmm. very small. it's 1+ 1/(2^16 *val) */
+
 		ret = i2c_smbus_read_word_data(chip->client,
 				ad7152_addresses[chan->channel][AD7152_GAIN]);
 		if (ret < 0)
 			return ret;
-		*val = ret;
+		/* 1 + gain_val / 2^16 */
+		*val = 1;
+		*val2 = (15625 * swab16(ret)) / 1024;
 
-		return IIO_VAL_INT;
+		return IIO_VAL_INT_PLUS_MICRO;
 	case (1 << IIO_CHAN_INFO_CALIBBIAS_SEPARATE):
 		ret = i2c_smbus_read_word_data(chip->client,
 				ad7152_addresses[chan->channel][AD7152_OFFS]);
 		if (ret < 0)
 			return ret;
-		*val = ret;
+		*val = swab16(ret);
 
 		return IIO_VAL_INT;
 	case (1 << IIO_CHAN_INFO_SCALE_SEPARATE):