[PATCH v2] iio: chemical: ccs811: Add support for data ready trigger

[PATCH v2] iio: chemical: ccs811: Add support for data ready trigger

[Narcisa Ana Maria Vasile]

Add data ready trigger for hardware interrupts that signal
new, available measurement samples.

Cc: Daniel Baluta <daniel.baluta@gmail.com>
Cc: Alison Schofield <amsfield22@gmail.com>
Signed-off-by: Narcisa Ana Maria Vasile <narcisaanamaria12@gmail.com>
---
Changes in v2:
    - Define top half handler for interrupts which calls iio_trigger_poll
    - Remove bottom half interrupt handler
    - Add bool variable to store the state of the data ready trigger
    - Remove threshold related macros and checks, as driver doesn't support
      threshold interrupts yet
    - Protect direct/buffered modes, by claiming direct mode in raw readings.
      Reading the data from ALG_RESULT_DATA will clear the data ready bit and
      will stop the nINT signal from being driven low. Therefore, disallow
      raw readings while hardware interrupts are active.
    - Rephrase commit message
Note:
    It may not be necessary to protect direct mode when performing raw readings,
    in that the data read may not be corrupted, but raw readings may "clear" the
    interrupt(clear the data-ready bit and nINT signal) before the handler deals
    with the interrupt, which doesn't seem like expected/acceptable behaviour.
    Thoughts on this?

 drivers/iio/chemical/ccs811.c | 87 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 86 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/chemical/ccs811.c b/drivers/iio/chemical/ccs811.c
index b59994d..c8ca1b9 100644
--- a/drivers/iio/chemical/ccs811.c
+++ b/drivers/iio/chemical/ccs811.c
@@ -23,6 +23,7 @@
 #include <linux/i2c.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/buffer.h>
+#include <linux/iio/trigger.h>
 #include <linux/iio/triggered_buffer.h>
 #include <linux/iio/trigger_consumer.h>
 #include <linux/module.h>
@@ -60,8 +61,12 @@
 #define CCS811_MODE_IAQ_60SEC	0x30
 #define CCS811_MODE_RAW_DATA	0x40

+#define CCS811_MEAS_MODE_INTERRUPT	BIT(3)
+
 #define CCS811_VOLTAGE_MASK	0x3FF

+#define CCS811_IRQ_NAME "ccs811_irq"
+
 struct ccs811_reading {
 	__be16 co2;
 	__be16 voc;
@@ -74,6 +79,8 @@ struct ccs811_data {
 	struct i2c_client *client;
 	struct mutex lock; /* Protect readings */
 	struct ccs811_reading buffer;
+	struct iio_trigger *drdy_trig;
+	bool drdy_trig_on;
 };

 static const struct iio_chan_spec ccs811_channels[] = {
@@ -194,10 +201,14 @@ static int ccs811_read_raw(struct iio_dev *indio_dev,

 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
+		ret = iio_device_claim_direct_mode(indio_dev);
+		if (ret)
+			return ret;
 		mutex_lock(&data->lock);
 		ret = ccs811_get_measurement(data);
 		if (ret < 0) {
 			mutex_unlock(&data->lock);
+			iio_device_release_direct_mode(indio_dev);
 			return ret;
 		}

@@ -229,6 +240,7 @@ static int ccs811_read_raw(struct iio_dev *indio_dev,
 			ret = -EINVAL;
 		}
 		mutex_unlock(&data->lock);
+		iio_device_release_direct_mode(indio_dev);

 		return ret;

@@ -274,6 +286,32 @@ static int ccs811_read_raw(struct iio_dev *indio_dev,
 	.driver_module = THIS_MODULE,
 };

+static int ccs811_set_trigger_state(struct iio_trigger *trig,
+				    bool state)
+{
+	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
+	struct ccs811_data *data = iio_priv(indio_dev);
+	int ret;
+
+	ret = i2c_smbus_read_byte_data(data->client, CCS811_MEAS_MODE);
+	if (ret < 0)
+		return ret;
+
+	if (state)
+		ret |= CCS811_MEAS_MODE_INTERRUPT;
+	else
+		ret &= ~CCS811_MEAS_MODE_INTERRUPT;
+
+	data->drdy_trig_on = state;
+
+	return i2c_smbus_write_byte_data(data->client, CCS811_MEAS_MODE, ret);
+}
+
+static const struct iio_trigger_ops ccs811_trigger_ops = {
+	.set_trigger_state = ccs811_set_trigger_state,
+	.owner = THIS_MODULE,
+};
+
 static irqreturn_t ccs811_trigger_handler(int irq, void *p)
 {
 	struct iio_poll_func *pf = p;
@@ -299,6 +337,17 @@ static irqreturn_t ccs811_trigger_handler(int irq, void *p)
 	return IRQ_HANDLED;
 }

+static irqreturn_t ccs811_data_rdy_trigger_poll(int irq, void *private)
+{
+	struct iio_dev *indio_dev = private;
+	struct ccs811_data *data = iio_priv(indio_dev);
+
+	if (data->drdy_trig_on)
+		iio_trigger_poll(data->drdy_trig);
+
+	return IRQ_HANDLED;
+}
+
 static int ccs811_probe(struct i2c_client *client,
 			const struct i2c_device_id *id)
 {
@@ -347,16 +396,48 @@ static int ccs811_probe(struct i2c_client *client,
 	indio_dev->dev.parent = &client->dev;
 	indio_dev->name = id->name;
 	indio_dev->info = &ccs811_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;

 	indio_dev->channels = ccs811_channels;
 	indio_dev->num_channels = ARRAY_SIZE(ccs811_channels);

+	if (client->irq > 0) {
+		ret = devm_request_threaded_irq(&client->dev, client->irq,
+						ccs811_data_rdy_trigger_poll,
+						NULL,
+						IRQF_TRIGGER_FALLING |
+						IRQF_ONESHOT,
+						CCS811_IRQ_NAME, indio_dev);
+		if (ret) {
+			dev_err(&client->dev, "irq request error %d\n", -ret);
+			goto err_poweroff;
+		}
+
+		data->drdy_trig = devm_iio_trigger_alloc(&client->dev,
+							 "%s-dev%d",
+							 indio_dev->name,
+							 indio_dev->id);
+		if (!data->drdy_trig) {
+			ret = -ENOMEM;
+			goto err_poweroff;
+		}
+
+		data->drdy_trig->dev.parent = &client->dev;
+		data->drdy_trig->ops = &ccs811_trigger_ops;
+		iio_trigger_set_drvdata(data->drdy_trig, indio_dev);
+		indio_dev->trig = data->drdy_trig;
+		iio_trigger_get(indio_dev->trig);
+		ret = iio_trigger_register(data->drdy_trig);
+		if (ret)
+			goto err_poweroff;
+	}
+
 	ret = iio_triggered_buffer_setup(indio_dev, NULL,
 					 ccs811_trigger_handler, NULL);

 	if (ret < 0) {
 		dev_err(&client->dev, "triggered buffer setup failed\n");
-		goto err_poweroff;
+		goto err_trigger_unregister;
 	}

 	ret = iio_device_register(indio_dev);
@@ -368,6 +449,8 @@ static int ccs811_probe(struct i2c_client *client,

 err_buffer_cleanup:
 	iio_triggered_buffer_cleanup(indio_dev);
+err_trigger_unregister:
+	iio_trigger_unregister(data->drdy_trig);
 err_poweroff:
 	i2c_smbus_write_byte_data(client, CCS811_MEAS_MODE, CCS811_MODE_IDLE);

@@ -377,9 +460,11 @@ static int ccs811_probe(struct i2c_client *client,
 static int ccs811_remove(struct i2c_client *client)
 {
 	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+	struct ccs811_data *data = iio_priv(indio_dev);

 	iio_device_unregister(indio_dev);
 	iio_triggered_buffer_cleanup(indio_dev);
+	iio_trigger_unregister(data->drdy_trig);

 	return i2c_smbus_write_byte_data(client, CCS811_MEAS_MODE,
 					 CCS811_MODE_IDLE);
--
1.9.1

Re: [PATCH v2] iio: chemical: ccs811: Add support for data ready trigger

[Jonathan Cameron]

On Thu, 24 Aug 2017 19:14:42 +0300
Narcisa Ana Maria Vasile <narcisaanamaria12@gmail.com> wrote:

> Add data ready trigger for hardware interrupts that signal
> new, available measurement samples.
> 
> Cc: Daniel Baluta <daniel.baluta@gmail.com>
> Cc: Alison Schofield <amsfield22@gmail.com>
> Signed-off-by: Narcisa Ana Maria Vasile <narcisaanamaria12@gmail.com>

One little point inline I missed in V1.

Sorry about that!

We are well past the end of the merge window for IIO now anyway so
there is plenty of time to clean this up.

The driver is coming together nicely.

Jonathan

> ---
> Changes in v2:
>     - Define top half handler for interrupts which calls iio_trigger_poll
>     - Remove bottom half interrupt handler
>     - Add bool variable to store the state of the data ready trigger
>     - Remove threshold related macros and checks, as driver doesn't support
>       threshold interrupts yet
>     - Protect direct/buffered modes, by claiming direct mode in raw readings.
>       Reading the data from ALG_RESULT_DATA will clear the data ready bit and
>       will stop the nINT signal from being driven low. Therefore, disallow
>       raw readings while hardware interrupts are active.
>     - Rephrase commit message
> Note:
>     It may not be necessary to protect direct mode when performing raw readings,
>     in that the data read may not be corrupted, but raw readings may "clear" the
>     interrupt(clear the data-ready bit and nINT signal) before the handler deals
>     with the interrupt, which doesn't seem like expected/acceptable behaviour.
>     Thoughts on this?

Do exactly what you have done here.  Better to be safe than sorry!
This is often the reason we prevent direct reads during buffered use. A direct
read results in a dropped reading 'sometimes' which is less than ideal.

> 
>  drivers/iio/chemical/ccs811.c | 87 ++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 86 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/chemical/ccs811.c b/drivers/iio/chemical/ccs811.c
> index b59994d..c8ca1b9 100644
> --- a/drivers/iio/chemical/ccs811.c
> +++ b/drivers/iio/chemical/ccs811.c
> @@ -23,6 +23,7 @@
>  #include <linux/i2c.h>
>  #include <linux/iio/iio.h>
>  #include <linux/iio/buffer.h>
> +#include <linux/iio/trigger.h>
>  #include <linux/iio/triggered_buffer.h>
>  #include <linux/iio/trigger_consumer.h>
>  #include <linux/module.h>
> @@ -60,8 +61,12 @@
>  #define CCS811_MODE_IAQ_60SEC	0x30
>  #define CCS811_MODE_RAW_DATA	0x40
> 
> +#define CCS811_MEAS_MODE_INTERRUPT	BIT(3)
> +
>  #define CCS811_VOLTAGE_MASK	0x3FF
> 
> +#define CCS811_IRQ_NAME "ccs811_irq"

Only used in once place, I'd just put in in directly
there rather than having the define.  Still easy to
grep for either way.
> +
>  struct ccs811_reading {
>  	__be16 co2;
>  	__be16 voc;
> @@ -74,6 +79,8 @@ struct ccs811_data {
>  	struct i2c_client *client;
>  	struct mutex lock; /* Protect readings */
>  	struct ccs811_reading buffer;
> +	struct iio_trigger *drdy_trig;
> +	bool drdy_trig_on;
>  };
> 
>  static const struct iio_chan_spec ccs811_channels[] = {
> @@ -194,10 +201,14 @@ static int ccs811_read_raw(struct iio_dev *indio_dev,
> 
>  	switch (mask) {
>  	case IIO_CHAN_INFO_RAW:
> +		ret = iio_device_claim_direct_mode(indio_dev);
> +		if (ret)
> +			return ret;
>  		mutex_lock(&data->lock);
>  		ret = ccs811_get_measurement(data);
>  		if (ret < 0) {
>  			mutex_unlock(&data->lock);
> +			iio_device_release_direct_mode(indio_dev);
>  			return ret;
>  		}
> 
> @@ -229,6 +240,7 @@ static int ccs811_read_raw(struct iio_dev *indio_dev,
>  			ret = -EINVAL;
>  		}
>  		mutex_unlock(&data->lock);
> +		iio_device_release_direct_mode(indio_dev);
> 
>  		return ret;
> 
> @@ -274,6 +286,32 @@ static int ccs811_read_raw(struct iio_dev *indio_dev,
>  	.driver_module = THIS_MODULE,
>  };
> 
> +static int ccs811_set_trigger_state(struct iio_trigger *trig,
> +				    bool state)
> +{
> +	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
> +	struct ccs811_data *data = iio_priv(indio_dev);
> +	int ret;
> +
> +	ret = i2c_smbus_read_byte_data(data->client, CCS811_MEAS_MODE);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (state)
> +		ret |= CCS811_MEAS_MODE_INTERRUPT;
> +	else
> +		ret &= ~CCS811_MEAS_MODE_INTERRUPT;
> +
> +	data->drdy_trig_on = state;
> +
> +	return i2c_smbus_write_byte_data(data->client, CCS811_MEAS_MODE, ret);
> +}
> +
> +static const struct iio_trigger_ops ccs811_trigger_ops = {
> +	.set_trigger_state = ccs811_set_trigger_state,
> +	.owner = THIS_MODULE,
> +};
> +
>  static irqreturn_t ccs811_trigger_handler(int irq, void *p)
>  {
>  	struct iio_poll_func *pf = p;
> @@ -299,6 +337,17 @@ static irqreturn_t ccs811_trigger_handler(int irq, void *p)
>  	return IRQ_HANDLED;
>  }
> 
> +static irqreturn_t ccs811_data_rdy_trigger_poll(int irq, void *private)
> +{
> +	struct iio_dev *indio_dev = private;
> +	struct ccs811_data *data = iio_priv(indio_dev);
> +
> +	if (data->drdy_trig_on)
> +		iio_trigger_poll(data->drdy_trig);
> +
> +	return IRQ_HANDLED;
> +}
> +
>  static int ccs811_probe(struct i2c_client *client,
>  			const struct i2c_device_id *id)
>  {
> @@ -347,16 +396,48 @@ static int ccs811_probe(struct i2c_client *client,
>  	indio_dev->dev.parent = &client->dev;
>  	indio_dev->name = id->name;
>  	indio_dev->info = &ccs811_info;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> 
>  	indio_dev->channels = ccs811_channels;
>  	indio_dev->num_channels = ARRAY_SIZE(ccs811_channels);
> 
> +	if (client->irq > 0) {
> +		ret = devm_request_threaded_irq(&client->dev, client->irq,
> +						ccs811_data_rdy_trigger_poll,
> +						NULL,
> +						IRQF_TRIGGER_FALLING |
> +						IRQF_ONESHOT,
> +						CCS811_IRQ_NAME, indio_dev);
> +		if (ret) {
> +			dev_err(&client->dev, "irq request error %d\n", -ret);
> +			goto err_poweroff;
> +		}
> +
> +		data->drdy_trig = devm_iio_trigger_alloc(&client->dev,
> +							 "%s-dev%d",
> +							 indio_dev->name,
> +							 indio_dev->id);
> +		if (!data->drdy_trig) {
> +			ret = -ENOMEM;
> +			goto err_poweroff;
> +		}
> +
> +		data->drdy_trig->dev.parent = &client->dev;
> +		data->drdy_trig->ops = &ccs811_trigger_ops;
> +		iio_trigger_set_drvdata(data->drdy_trig, indio_dev);
> +		indio_dev->trig = data->drdy_trig;
> +		iio_trigger_get(indio_dev->trig);
> +		ret = iio_trigger_register(data->drdy_trig);
> +		if (ret)
> +			goto err_poweroff;
> +	}
> +
>  	ret = iio_triggered_buffer_setup(indio_dev, NULL,
>  					 ccs811_trigger_handler, NULL);
> 
>  	if (ret < 0) {
>  		dev_err(&client->dev, "triggered buffer setup failed\n");
> -		goto err_poweroff;
> +		goto err_trigger_unregister;
>  	}
> 
>  	ret = iio_device_register(indio_dev);
> @@ -368,6 +449,8 @@ static int ccs811_probe(struct i2c_client *client,
> 
>  err_buffer_cleanup:
>  	iio_triggered_buffer_cleanup(indio_dev);
> +err_trigger_unregister:
> +	iio_trigger_unregister(data->drdy_trig);

I missed this on the first pass.  Given the trigger is optional, it may still
be null.  There is no protection in iio_trigger_unregister for this
(it could be easily added though).  Hence you should be checking before
attempting to unregister.

>  err_poweroff:
>  	i2c_smbus_write_byte_data(client, CCS811_MEAS_MODE, CCS811_MODE_IDLE);
> 
> @@ -377,9 +460,11 @@ static int ccs811_probe(struct i2c_client *client,
>  static int ccs811_remove(struct i2c_client *client)
>  {
>  	struct iio_dev *indio_dev = i2c_get_clientdata(client);
> +	struct ccs811_data *data = iio_priv(indio_dev);
> 
>  	iio_device_unregister(indio_dev);
>  	iio_triggered_buffer_cleanup(indio_dev);
> +	iio_trigger_unregister(data->drdy_trig);
> 
>  	return i2c_smbus_write_byte_data(client, CCS811_MEAS_MODE,
>  					 CCS811_MODE_IDLE);
> --
> 1.9.1
>