From f73d05506794b6f4090e4c5c701c2362a66b07ec Mon Sep 17 00:00:00 2001
From: Petr Nechaev <petr.nechaev@cogentembedded.com>
Date: Wed, 28 Oct 2015 16:24:28 +0300
Subject: [PATCH 1/1] Cleanup TI ADS111x ADC driver

* added locks for simultaneous multi-channel read
* fixed error messages
* converted result to signed 16-bit value
* added safeguard against channel numbers > 7
---
 drivers/iio/adc/ti-ads111x.c | 96 ++++++++++++++++++++++++++++++--------------
 1 file changed, 66 insertions(+), 30 deletions(-)

diff --git a/drivers/iio/adc/ti-ads111x.c b/drivers/iio/adc/ti-ads111x.c
index 98a28e3e..bf91e04 100644
--- a/drivers/iio/adc/ti-ads111x.c
+++ b/drivers/iio/adc/ti-ads111x.c
@@ -12,7 +12,6 @@
 #include <linux/delay.h>

 #include <linux/iio/iio.h>
-#include <linux/regulator/consumer.h>

 #define REG_CONV_RES		0x00
 #define REG_CONFIG		0x01
@@ -22,7 +21,7 @@
 /* CONFIG reg bits */
 /* w: begin sigle conversion; r: operation status */
 #define CONFIG_OS		(1 << 15)
-#define CONFIG_CH(n)		(n << 12)
+#define CONFIG_CH(n)		((n & 0x7) << 12)
 /* ADS1114/5 only */
 #define CONFIG_PGA_6144		(0 << 9)
 #define CONFIG_PGA_4096		(1 << 9)
@@ -80,7 +79,7 @@ enum ads1115_modes {
 		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
 		.datasheet_name = "AIN"#num,				\
 		.scan_type = {						\
-			.sign = 'u',					\
+			.sign = 's',					\
 			.realbits = 16,					\
 			.storagebits = 16,				\
 			.endianness = IIO_BE,				\
@@ -100,7 +99,7 @@ enum ads1115_modes {
 		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
 		.datasheet_name = "AIN"#num"-AIN"#num2,			\
 		.scan_type = {						\
-			.sign = 'u',					\
+			.sign = 's',					\
 			.realbits = 16,					\
 			.storagebits = 16,				\
 			.endianness = IIO_BE,				\
@@ -120,45 +119,81 @@ static const struct iio_chan_spec ads111x_channels[] = {
 	ADS1115_CHAN_U(3, p3),
 };

-static int ads111x_read_raw(struct iio_dev *iio,
-			    struct iio_chan_spec const *channel, int *value,
-			    int *shift, long mask)
+static int ads111x_read_single_channel(struct iio_dev *iio,
+				       struct iio_chan_spec const *channel,
+				       int *value)
 {
-	struct ads111x *adc = iio_priv(iio);
 	u16 config_reg;
-	int err;
+	int ret;
+	int iter;
+	struct ads111x *adc = iio_priv(iio);

-	switch (mask) {
-	case IIO_CHAN_INFO_RAW:
-		config_reg =
+	mutex_lock(&iio->mlock);
+
+	/* start the conversion */
+	config_reg =
 			CONFIG_OS |
 			CONFIG_CH(channel->address) |
 			CONFIG_PGA_2048 |
 			CONFIG_MODE_SINGLE |
 			CONFIG_DR_860SPS |
 			CONFIG_COMP_QUE_DIS;
-		err = i2c_smbus_write_word_swapped(adc->i2c, REG_CONFIG, config_reg);
-		if (err < 0) {
-			dev_err(&iio->dev, "REG_CONFIG write err %d\n", err);
-			return err;
-		}
-		mdelay(1);
-		err = i2c_smbus_read_word_swapped(adc->i2c, REG_CONFIG);
-		if (err < 0) {
-			dev_err(&iio->dev, "REG_CONFIG read err %d\n", err);
-			return err;
+	ret = i2c_smbus_write_word_swapped(adc->i2c, REG_CONFIG, config_reg);
+	if (ret < 0) {
+		dev_err(&iio->dev, "Error writing to REG_CONFIG %d\n", ret);
+		goto error_ret;
+	}
+
+	for (iter = 0; iter < 2; iter++)
+	{
+		/* wait for conversion to complete */
+		ret = msleep_interruptible(2);
+		if (ret < 0)
+			goto error_ret;
+
+		/* read status */
+		ret = i2c_smbus_read_word_swapped(adc->i2c, REG_CONFIG);
+		if (ret < 0) {
+			dev_err(&iio->dev, "Error reading REG_CONFIG %d\n", ret);
+			goto error_ret;
 		}
-		if (err & CONFIG_OS) {
-			dev_err(&iio->dev, "ADC not ready 0x%04x\n", err);
-			return -EBUSY;
+		if ((ret & CONFIG_OS) != CONFIG_OS) {
+			dev_err(&iio->dev, "ADC not ready 0x%04x\n", ret);
+			ret = -EBUSY;
+			continue;
 		}
-		err = i2c_smbus_read_word_swapped(adc->i2c, REG_CONV_RES);
-		if (err < 0) {
-			dev_err(&iio->dev, "REG_CONV_RES read err %d\n", err);
+	}
+	if (ret < 0)
+		goto error_ret;
+
+	/* read value */
+	ret = i2c_smbus_read_word_swapped(adc->i2c, REG_CONV_RES);
+	if (ret < 0) {
+		dev_err(&iio->dev, "Error reading REG_CONV_RES %d\n", ret);
+		goto error_ret;
+	}
+
+	*value = (s16) (ret & 0xFFFF);
+	ret = 1;
+
+error_ret:
+	mutex_unlock(&iio->mlock);
+	return ret;
+
+}
+
+static int ads111x_read_raw(struct iio_dev *iio,
+			    struct iio_chan_spec const *channel, int *value,
+			    int *shift, long mask)
+{
+	int err;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		err = ads111x_read_single_channel(iio, channel, value);
+		if (err < 0)
 			return err;
-		}

-		*value = err;
 		return IIO_VAL_INT;

 	case IIO_CHAN_INFO_SCALE:
--
2.4.3