i2c: added i2c quirk flag for unsupported clock stretching

index 768063b..9697002 100644
@@ -493,6 +493,8 @@ struct i2c_adapter_quirks {
 /* convenience macro for typical write-then read case */
 #define I2C_AQ_COMB_WRITE_THEN_READ	(I2C_AQ_COMB | I2C_AQ_COMB_WRITE_FIRST | \
 					 I2C_AQ_COMB_READ_SECOND | I2C_AQ_COMB_SAME_ADDR)
+/* clock stretching is not supported */
+#define I2C_AQ_NO_CLK_STRETCH		BIT(4)
 
 /*
  * i2c_adapter is the structure used to identify a physical i2c bus along

index 899bede..9d233bb 100644
@@ -617,6 +617,10 @@ const struct i2c_algorithm i2c_bit_algo = {
 };
 EXPORT_SYMBOL(i2c_bit_algo);
 
+const struct i2c_adapter_quirks i2c_bit_quirk_no_clk_stretch = {
+	.flags = I2C_AQ_NO_CLK_STRETCH,
+};
+
 /*
  * registering functions to load algorithms at runtime
  */

@@ -635,6 +639,8 @@ static int __i2c_bit_add_bus(struct i2c_adapter *adap,
 	/* register new adapter to i2c module... */
 	adap->algo = &i2c_bit_algo;
 	adap->retries = 3;
+	if (bit_adap->getscl == NULL)
+		adap->quirks = &i2c_bit_quirk_no_clk_stretch;
 
 	ret = add_adapter(adap);
 	if (ret < 0)

index 3032b89..38d7102 100644
@@ -222,6 +222,10 @@ static const struct i2c_algorithm bcm2835_i2c_algo = {
 	.functionality	= bcm2835_i2c_func,
 };
 
+static const struct i2c_adapter_quirks bcm2835_i2c_quirks = {
+	.flags = I2C_AQ_NO_CLK_STRETCH,
+};
+
 static int bcm2835_i2c_probe(struct platform_device *pdev)
 {
 	struct bcm2835_i2c_dev *i2c_dev;

@@ -293,6 +297,7 @@ static int bcm2835_i2c_probe(struct platform_device *pdev)
 	adap->algo = &bcm2835_i2c_algo;
 	adap->dev.parent = &pdev->dev;
 	adap->dev.of_node = pdev->dev.of_node;
+	adap->quirks = &bcm2835_i2c_quirks;
 
 	bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, 0);
 

index 12128d1..cb65f34 100644
@@ -2,6 +2,7 @@
  * si7020.c - Silicon Labs Si7013/20/21 Relative Humidity and Temp Sensors
  * Copyright (c) 2013,2014  Uplogix, Inc.
  * David Barksdale <[email protected]>
+ * Copyright (c) 2015 Nicola Corna <[email protected]>
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms and conditions of the GNU General Public License,

@@ -30,33 +31,79 @@
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/sysfs.h>
+#include <linux/jiffies.h>
 
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
+#include <linux/platform_data/si7020.h>
 
 /* Measure Relative Humidity, Hold Master Mode */
 #define SI7020CMD_RH_HOLD	0xE5
+/* Measure Relative Humidity, No Hold Master Mode */
+#define SI7020CMD_RH_NO_HOLD	0xF5
 /* Measure Temperature, Hold Master Mode */
 #define SI7020CMD_TEMP_HOLD	0xE3
+/* Measure Temperature, No Hold Master Mode */
+#define SI7020CMD_TEMP_NO_HOLD	0xF3
 /* Software Reset */
 #define SI7020CMD_RESET		0xFE
+/* Relative humidity measurement timeout (us) */
+#define SI7020_RH_TIMEOUT	22800
+/* Temperature measurement timeout (us) */
+#define SI7020_TEMP_TIMEOUT	10800
+/* Minimum delay between retries (No Hold Mode) in us */
+#define SI7020_NOHOLD_SLEEP_MIN	2000
+/* Maximum delay between retries (No Hold Mode) in us */
+#define SI7020_NOHOLD_SLEEP_MAX	6000
 
 static int si7020_read_raw(struct iio_dev *indio_dev,
 			   struct iio_chan_spec const *chan, int *val,
 			   int *val2, long mask)
 {
 	struct i2c_client **client = iio_priv(indio_dev);
+	struct si7020_platform_data *pdata;
 	int ret;
+	bool holdmode;
+	unsigned char buf[2];
+	unsigned long start;
 
 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
-		ret = i2c_smbus_read_word_data(*client,
-					       chan->type == IIO_TEMP ?
-					       SI7020CMD_TEMP_HOLD :
-					       SI7020CMD_RH_HOLD);
-		if (ret < 0)
-			return ret;
-		*val = ret >> 2;
+		pdata = dev_get_platdata(&(*client)->dev);
+		if (pdata)
+			holdmode = pdata->blocking_io;
+		else
+			holdmode = !((*client)->adapter->quirks &&
+					(*client)->adapter->quirks->flags |
+					I2C_AQ_NO_CLK_STRETCH);
+		if (holdmode) {
+			ret = i2c_smbus_read_word_data(*client,
+						       chan->type == IIO_TEMP ?
+						       SI7020CMD_TEMP_HOLD :
+						       SI7020CMD_RH_HOLD);
+			if (ret < 0)
+				return ret;
+			*val = ret >> 2;
+		} else {
+			ret = i2c_smbus_write_byte(*client,
+						   chan->type == IIO_TEMP ?
+						   SI7020CMD_TEMP_NO_HOLD :
+						   SI7020CMD_RH_NO_HOLD);
+			if (ret < 0)
+				return ret;
+			start = jiffies;
+			while ((ret = i2c_master_recv(*client, buf, 2)) < 0) {
+				if (time_after(jiffies, start +
+					       usecs_to_jiffies(
+							chan->type == IIO_TEMP ?
+							SI7020_TEMP_TIMEOUT :
+							SI7020_RH_TIMEOUT)))
+					return ret;
+				usleep_range(SI7020_NOHOLD_SLEEP_MIN,
+					     SI7020_NOHOLD_SLEEP_MAX);
+			}
+			*val = ((buf[0] << 8) | buf[1]) >> 2;
+		}
 		/*
 		 * Humidity values can slightly exceed the 0-100%RH
 		 * range and should be corrected by software

@@ -116,6 +163,7 @@ static int si7020_probe(struct i2c_client *client,
 {
 	struct iio_dev *indio_dev;
 	struct i2c_client **data;
+	struct si7020_platform_data *pdata;
 	int ret;
 
 	if (!i2c_check_functionality(client->adapter,

@@ -123,6 +171,22 @@ static int si7020_probe(struct i2c_client *client,
 				     I2C_FUNC_SMBUS_READ_WORD_DATA))
 		return -ENODEV;
 
+	pdata = dev_get_platdata(&client->dev);
+	if (pdata) {
+		if (pdata->blocking_io) {
+			if (client->adapter->quirks &&
+			   client->adapter->quirks->flags |
+			   I2C_AQ_NO_CLK_STRETCH)
+				return -ENODEV;
+		} else if (!i2c_check_functionality(client->adapter,
+			  I2C_FUNC_I2C))
+			return -ENODEV;
+	} else
+		if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C) &&
+		   client->adapter->quirks &&
+		   client->adapter->quirks->flags | I2C_AQ_NO_CLK_STRETCH)
+			return -ENODEV;
+
 	/* Reset device, loads default settings. */
 	ret = i2c_smbus_write_byte(client, SI7020CMD_RESET);
 	if (ret < 0)

new file mode 100644
index 0000000..8bb5848
@@ -0,0 +1,21 @@
+/*
+ * Copyright (C) 2015 Nicola Corna <[email protected]>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#ifndef __SI7020_H_
+#define __SI7020_H_
+
+struct si7020_platform_data {
+	bool blocking_io;
+};
+#endif /* __SI7020_H_ */

index 12128d1..c728681 100644
@@ -2,6 +2,7 @@
  * si7020.c - Silicon Labs Si7013/20/21 Relative Humidity and Temp Sensors
  * Copyright (c) 2013,2014  Uplogix, Inc.
  * David Barksdale <[email protected]>
+ * Copyright (c) 2015 Nicola Corna <[email protected]>
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms and conditions of the GNU General Public License,

@@ -30,33 +31,79 @@
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/sysfs.h>
+#include <linux/jiffies.h>
 
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
+#include <linux/platform_data/si7020.h>
 
 /* Measure Relative Humidity, Hold Master Mode */
 #define SI7020CMD_RH_HOLD	0xE5
+/* Measure Relative Humidity, No Hold Master Mode */
+#define SI7020CMD_RH_NO_HOLD	0xF5
 /* Measure Temperature, Hold Master Mode */
 #define SI7020CMD_TEMP_HOLD	0xE3
+/* Measure Temperature, No Hold Master Mode */
+#define SI7020CMD_TEMP_NO_HOLD	0xF3
 /* Software Reset */
 #define SI7020CMD_RESET		0xFE
+/* Relative humidity measurement timeout (us) */
+#define SI7020_RH_TIMEOUT	22800
+/* Temperature measurement timeout (us) */
+#define SI7020_TEMP_TIMEOUT	10800
+/* Minimum delay between retries (No Hold Mode) in us */
+#define SI7020_NOHOLD_SLEEP_MIN	2000
+/* Maximum delay between retries (No Hold Mode) in us */
+#define SI7020_NOHOLD_SLEEP_MAX	6000
 
 static int si7020_read_raw(struct iio_dev *indio_dev,
 			   struct iio_chan_spec const *chan, int *val,
 			   int *val2, long mask)
 {
 	struct i2c_client **client = iio_priv(indio_dev);
+	struct si7020_platform_data *pdata;
 	int ret;
+	bool holdmode;
+	unsigned char buf[2];
+	unsigned long start;
 
 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
-		ret = i2c_smbus_read_word_data(*client,
-					       chan->type == IIO_TEMP ?
-					       SI7020CMD_TEMP_HOLD :
-					       SI7020CMD_RH_HOLD);
-		if (ret < 0)
-			return ret;
-		*val = ret >> 2;
+		pdata = dev_get_platdata(&(*client)->dev);
+		if (pdata)
+			holdmode = pdata->blocking_io;
+		else
+			holdmode = !((*client)->adapter->quirks &&
+					(*client)->adapter->quirks->flags &
+					I2C_AQ_NO_CLK_STRETCH);
+		if (holdmode) {
+			ret = i2c_smbus_read_word_data(*client,
+						       chan->type == IIO_TEMP ?
+						       SI7020CMD_TEMP_HOLD :
+						       SI7020CMD_RH_HOLD);
+			if (ret < 0)
+				return ret;
+			*val = ret >> 2;
+		} else {
+			ret = i2c_smbus_write_byte(*client,
+						   chan->type == IIO_TEMP ?
+						   SI7020CMD_TEMP_NO_HOLD :
+						   SI7020CMD_RH_NO_HOLD);
+			if (ret < 0)
+				return ret;
+			start = jiffies;
+			while ((ret = i2c_master_recv(*client, buf, 2)) < 0) {
+				if (time_after(jiffies, start +
+					       usecs_to_jiffies(
+							chan->type == IIO_TEMP ?
+							SI7020_TEMP_TIMEOUT :
+							SI7020_RH_TIMEOUT)))
+					return ret;
+				usleep_range(SI7020_NOHOLD_SLEEP_MIN,
+					     SI7020_NOHOLD_SLEEP_MAX);
+			}
+			*val = ((buf[0] << 8) | buf[1]) >> 2;
+		}
 		/*
 		 * Humidity values can slightly exceed the 0-100%RH
 		 * range and should be corrected by software

@@ -116,6 +163,7 @@ static int si7020_probe(struct i2c_client *client,
 {
 	struct iio_dev *indio_dev;
 	struct i2c_client **data;
+	struct si7020_platform_data *pdata;
 	int ret;
 
 	if (!i2c_check_functionality(client->adapter,

@@ -123,6 +171,22 @@ static int si7020_probe(struct i2c_client *client,
 				     I2C_FUNC_SMBUS_READ_WORD_DATA))
 		return -ENODEV;
 
+	pdata = dev_get_platdata(&client->dev);
+	if (pdata) {
+		if (pdata->blocking_io) {
+			if (client->adapter->quirks &&
+			   client->adapter->quirks->flags &
+			   I2C_AQ_NO_CLK_STRETCH)
+				return -ENODEV;
+		} else if (!i2c_check_functionality(client->adapter,
+			  I2C_FUNC_I2C))
+			return -ENODEV;
+	} else
+		if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C) &&
+		   client->adapter->quirks &&
+		   client->adapter->quirks->flags & I2C_AQ_NO_CLK_STRETCH)
+			return -ENODEV;
+
 	/* Reset device, loads default settings. */
 	ret = i2c_smbus_write_byte(client, SI7020CMD_RESET);
 	if (ret < 0)

new file mode 100644
index 0000000..8bb5848
@@ -0,0 +1,21 @@
+/*
+ * Copyright (C) 2015 Nicola Corna <[email protected]>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#ifndef __SI7020_H_
+#define __SI7020_H_
+
+struct si7020_platform_data {
+	bool blocking_io;
+};
+#endif /* __SI7020_H_ */

index a69a9a0..a06ffc0 100644
@@ -613,6 +613,12 @@ static inline int i2c_check_functionality(struct i2c_adapter *adap, u32 func)

index 768063b..9697002 100644
@@ -493,6 +493,8 @@ struct i2c_adapter_quirks {
 /* convenience macro for typical write-then read case */
 #define I2C_AQ_COMB_WRITE_THEN_READ	(I2C_AQ_COMB | I2C_AQ_COMB_WRITE_FIRST | \
 					 I2C_AQ_COMB_READ_SECOND | I2C_AQ_COMB_SAME_ADDR)
+/* clock stretching is not supported */
+#define I2C_AQ_NO_CLK_STRETCH		BIT(4)
 
 /*
  * i2c_adapter is the structure used to identify a physical i2c bus along

index 899bede..9d233bb 100644
@@ -617,6 +617,10 @@ const struct i2c_algorithm i2c_bit_algo = {
 };
 EXPORT_SYMBOL(i2c_bit_algo);
 
+const struct i2c_adapter_quirks i2c_bit_quirk_no_clk_stretch = {
+	.flags = I2C_AQ_NO_CLK_STRETCH,
+};
+
 /*
  * registering functions to load algorithms at runtime
  */

@@ -635,6 +639,8 @@ static int __i2c_bit_add_bus(struct i2c_adapter *adap,
 	/* register new adapter to i2c module... */
 	adap->algo = &i2c_bit_algo;
 	adap->retries = 3;
+	if (bit_adap->getscl == NULL)
+		adap->quirks = &i2c_bit_quirk_no_clk_stretch;
 
 	ret = add_adapter(adap);
 	if (ret < 0)

index 3032b89..38d7102 100644
@@ -222,6 +222,10 @@ static const struct i2c_algorithm bcm2835_i2c_algo = {
 	.functionality	= bcm2835_i2c_func,
 };
 
+static const struct i2c_adapter_quirks bcm2835_i2c_quirks = {
+	.flags = I2C_AQ_NO_CLK_STRETCH,
+};
+
 static int bcm2835_i2c_probe(struct platform_device *pdev)
 {
 	struct bcm2835_i2c_dev *i2c_dev;

@@ -293,6 +297,7 @@ static int bcm2835_i2c_probe(struct platform_device *pdev)
 	adap->algo = &bcm2835_i2c_algo;
 	adap->dev.parent = &pdev->dev;
 	adap->dev.of_node = pdev->dev.of_node;
+	adap->quirks = &bcm2835_i2c_quirks;
 
 	bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, 0);
 

index 9697002..51028f3 100644
@@ -617,6 +617,20 @@ static inline int i2c_check_functionality(struct i2c_adapter *adap, u32 func)
 	return (func & i2c_get_functionality(adap)) == func;
 }
 
+/**
+ * i2c_check_quirks() - Function for checking the quirk flags in an i2c adapter
+ * @adap: i2c adapter
+ * @quirks: quirk flags
+ *
+ * Return: true if the adapter has all the specified quirk flags, false if not
+ */
+static inline bool i2c_check_quirks(struct i2c_adapter *adap, u64 quirks)
+{
+	if (!adap->quirks)
+		return false;
+	return (adap->quirks->flags & quirks) == quirks;
+}
+
 /* Return the adapter number for a specific adapter */
 static inline int i2c_adapter_id(struct i2c_adapter *adap)
 {

index 12128d1..674a61a 100644
@@ -2,6 +2,7 @@
  * si7020.c - Silicon Labs Si7013/20/21 Relative Humidity and Temp Sensors
  * Copyright (c) 2013,2014  Uplogix, Inc.
  * David Barksdale <[email protected]>
+ * Copyright (c) 2015 Nicola Corna <[email protected]>
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms and conditions of the GNU General Public License,

@@ -30,33 +31,78 @@
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/sysfs.h>
+#include <linux/jiffies.h>
 
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
+#include <linux/platform_data/si7020.h>
 
 /* Measure Relative Humidity, Hold Master Mode */
 #define SI7020CMD_RH_HOLD	0xE5
+/* Measure Relative Humidity, No Hold Master Mode */
+#define SI7020CMD_RH_NO_HOLD	0xF5
 /* Measure Temperature, Hold Master Mode */
 #define SI7020CMD_TEMP_HOLD	0xE3
+/* Measure Temperature, No Hold Master Mode */
+#define SI7020CMD_TEMP_NO_HOLD	0xF3
 /* Software Reset */
 #define SI7020CMD_RESET		0xFE
+/* Relative humidity measurement timeout (us) */
+#define SI7020_RH_TIMEOUT	22800
+/* Temperature measurement timeout (us) */
+#define SI7020_TEMP_TIMEOUT	10800
+/* Minimum delay between retries (No Hold Mode) in us */
+#define SI7020_NOHOLD_SLEEP_MIN	2000
+/* Maximum delay between retries (No Hold Mode) in us */
+#define SI7020_NOHOLD_SLEEP_MAX	6000
 
 static int si7020_read_raw(struct iio_dev *indio_dev,
 			   struct iio_chan_spec const *chan, int *val,
 			   int *val2, long mask)
 {
 	struct i2c_client **client = iio_priv(indio_dev);
+	struct si7020_platform_data *pdata;
 	int ret;
+	bool holdmode;
+	unsigned char buf[2];
+	unsigned long start;
 
 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
-		ret = i2c_smbus_read_word_data(*client,
-					       chan->type == IIO_TEMP ?
-					       SI7020CMD_TEMP_HOLD :
-					       SI7020CMD_RH_HOLD);
-		if (ret < 0)
-			return ret;
-		*val = ret >> 2;
+		pdata = dev_get_platdata(&(*client)->dev);
+		if (pdata)
+			holdmode = pdata->blocking_io;
+		else
+			holdmode = !i2c_check_quirks((*client)->adapter,
+				   I2C_AQ_NO_CLK_STRETCH);
+		if (holdmode) {
+			ret = i2c_smbus_read_word_data(*client,
+						       chan->type == IIO_TEMP ?
+						       SI7020CMD_TEMP_HOLD :
+						       SI7020CMD_RH_HOLD);
+			if (ret < 0)
+				return ret;
+			*val = ret >> 2;
+		} else {
+			ret = i2c_smbus_write_byte(*client,
+						   chan->type == IIO_TEMP ?
+						   SI7020CMD_TEMP_NO_HOLD :
+						   SI7020CMD_RH_NO_HOLD);
+			if (ret < 0)
+				return ret;
+			start = jiffies;
+			while ((ret = i2c_master_recv(*client, buf, 2)) < 0) {
+				if (time_after(jiffies, start +
+					       usecs_to_jiffies(
+							chan->type == IIO_TEMP ?
+							SI7020_TEMP_TIMEOUT :
+							SI7020_RH_TIMEOUT)))
+					return ret;
+				usleep_range(SI7020_NOHOLD_SLEEP_MIN,
+					     SI7020_NOHOLD_SLEEP_MAX);
+			}
+			*val = ((buf[0] << 8) | buf[1]) >> 2;
+		}
 		/*
 		 * Humidity values can slightly exceed the 0-100%RH
 		 * range and should be corrected by software

@@ -116,6 +162,7 @@ static int si7020_probe(struct i2c_client *client,
 {
 	struct iio_dev *indio_dev;
 	struct i2c_client **data;
+	struct si7020_platform_data *pdata;
 	int ret;
 
 	if (!i2c_check_functionality(client->adapter,

@@ -123,6 +170,20 @@ static int si7020_probe(struct i2c_client *client,
 				     I2C_FUNC_SMBUS_READ_WORD_DATA))
 		return -ENODEV;
 
+	pdata = dev_get_platdata(&client->dev);
+	if (pdata) {
+		if (pdata->blocking_io) {
+			if (i2c_check_quirks(client->adapter,
+			   I2C_AQ_NO_CLK_STRETCH))
+				return -ENODEV;
+		} else if (!i2c_check_functionality(client->adapter,
+			  I2C_FUNC_I2C))
+			return -ENODEV;
+	} else
+		if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C) &&
+		   i2c_check_quirks(client->adapter, I2C_AQ_NO_CLK_STRETCH))
+			return -ENODEV;
+
 	/* Reset device, loads default settings. */
 	ret = i2c_smbus_write_byte(client, SI7020CMD_RESET);
 	if (ret < 0)

new file mode 100644
index 0000000..8bb5848
@@ -0,0 +1,21 @@
+/*
+ * Copyright (C) 2015 Nicola Corna <[email protected]>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#ifndef __SI7020_H_
+#define __SI7020_H_
+
+struct si7020_platform_data {
+	bool blocking_io;
+};
+#endif /* __SI7020_H_ */