[PATCH v2 0/3] Add Reset and Wakeup support for CCS811

[PATCH v2 0/3] Add Reset and Wakeup support for CCS811

[mani]

From: Manivannan Sadhasivam <mani@kernel.org>

Hello,

This patchset adds external reset and wakeup support for CCS811 VOC
gas sensor. The nRESET and nWAKE pins available on the device are
utilised to provide these functionalities.

The patchset has been validated using CCS811 connected to STM32MP1 based
board over I2C.

While at it, the devicetree yaml binding and OF match table for this sensor
are also added.

Thanks,
Mani

Changes in v2:

* Fixed DT binding schema and switched to dual license (GPL/BSD)
* Returned actual error code from devm_gpiod_get_optional()
* Dropped of.h include and of_match_ptr()

Manivannan Sadhasivam (3):
  dt-bindings: iio: chemical: Add binding for CCS811 VOC sensor
  iio: chemical: Add support for external Reset and Wakeup in CCS811
  iio: chemical: Add OF match table for CCS811 VOC sensor

 .../bindings/iio/chemical/ams,ccs811.yaml     | 51 ++++++++++
 drivers/iio/chemical/ccs811.c                 | 95 +++++++++++++++++--
 2 files changed, 138 insertions(+), 8 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/iio/chemical/ams,ccs811.yaml

-- 
2.17.1

[PATCH v2 1/3] dt-bindings: iio: chemical: Add binding for CCS811 VOC sensor

[mani]

From: Manivannan Sadhasivam <mani@kernel.org>

This commit adds devicetree binding for AMS CCS811 VOC sensor.

Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
---
 .../bindings/iio/chemical/ams,ccs811.yaml     | 51 +++++++++++++++++++
 1 file changed, 51 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/chemical/ams,ccs811.yaml

diff --git a/Documentation/devicetree/bindings/iio/chemical/ams,ccs811.yaml b/Documentation/devicetree/bindings/iio/chemical/ams,ccs811.yaml
new file mode 100644
index 000000000000..5cb068666a3e
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/chemical/ams,ccs811.yaml
@@ -0,0 +1,51 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/chemical/ams,ccs811.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: AMS CCS811 VOC Sensor
+
+maintainers:
+  - Narcisa Vasile <narcisaanamaria12@gmail.com>
+
+description: |
+  Ultra-Low Power Digital Gas Sensor for Monitoring Indoor Air Quality.
+
+properties:
+  compatible:
+    enum:
+      - ams,ccs811
+  reg:
+    maxItems: 1
+
+  reset-gpios:
+    description: GPIO connected to the nRESET line. This is an active low
+                 input to CCS811.
+    maxItems: 1
+
+  wakeup-gpios:
+    description: GPIO connected to the nWAKE line. This is an active low
+                 input to CCS811.
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    i2c {
+      #address-cells = <1>;
+      #size-cells = <0>;
+
+      voc@5b {
+        compatible = "ams,ccs811";
+        reg = <0x5b>;
+        reset-gpios = <&gpioa 11 GPIO_ACTIVE_LOW>;
+        wakeup-gpios = <&gpioa 12 GPIO_ACTIVE_LOW>;
+      };
+    };
+
+...
-- 
2.17.1

[PATCH v2 2/3] iio: chemical: Add support for external Reset and Wakeup in CCS811

[mani]

From: Manivannan Sadhasivam <mani@kernel.org>

CCS811 VOC sensor exposes nRESET and nWAKE pins which can be connected
to GPIO pins of the host controller. These pins can be used to externally
release the device from reset and also to wake it up before any I2C
transaction. The initial driver support assumed that the nRESET pin is not
connected and the nWAKE pin is tied to ground.

This commit improves it by adding support for controlling those two pins
externally using a host controller. For the case of reset, if the hardware
reset is not available, the mechanism to do software reset is also added.

As a side effect of doing this, the IIO device allocation needs to be
slightly moved to top of probe to make use of priv data early.

Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
---
 drivers/iio/chemical/ccs811.c | 88 +++++++++++++++++++++++++++++++----
 1 file changed, 80 insertions(+), 8 deletions(-)

diff --git a/drivers/iio/chemical/ccs811.c b/drivers/iio/chemical/ccs811.c
index 2ebdfc35bcda..951358710f64 100644
--- a/drivers/iio/chemical/ccs811.c
+++ b/drivers/iio/chemical/ccs811.c
@@ -16,6 +16,7 @@
  */
 
 #include <linux/delay.h>
+#include <linux/gpio/consumer.h>
 #include <linux/i2c.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/buffer.h>
@@ -36,6 +37,7 @@
 #define CCS811_ERR		0xE0
 /* Used to transition from boot to application mode */
 #define CCS811_APP_START	0xF4
+#define CCS811_SW_RESET		0xFF
 
 /* Status register flags */
 #define CCS811_STATUS_ERROR		BIT(0)
@@ -74,6 +76,7 @@ struct ccs811_data {
 	struct mutex lock; /* Protect readings */
 	struct ccs811_reading buffer;
 	struct iio_trigger *drdy_trig;
+	struct gpio_desc *wakeup_gpio;
 	bool drdy_trig_on;
 };
 
@@ -166,10 +169,25 @@ static int ccs811_setup(struct i2c_client *client)
 					 CCS811_MODE_IAQ_1SEC);
 }
 
+static void ccs811_set_wakeup(struct ccs811_data *data, bool enable)
+{
+	if (!data->wakeup_gpio)
+		return;
+
+	gpiod_set_value(data->wakeup_gpio, enable);
+
+	if (enable)
+		usleep_range(50, 60);
+	else
+		usleep_range(20, 30);
+}
+
 static int ccs811_get_measurement(struct ccs811_data *data)
 {
 	int ret, tries = 11;
 
+	ccs811_set_wakeup(data, true);
+
 	/* Maximum waiting time: 1s, as measurements are made every second */
 	while (tries-- > 0) {
 		ret = i2c_smbus_read_byte_data(data->client, CCS811_STATUS);
@@ -183,9 +201,12 @@ static int ccs811_get_measurement(struct ccs811_data *data)
 	if (!(ret & CCS811_STATUS_DATA_READY))
 		return -EIO;
 
-	return i2c_smbus_read_i2c_block_data(data->client,
+	ret = i2c_smbus_read_i2c_block_data(data->client,
 					    CCS811_ALG_RESULT_DATA, 8,
 					    (char *)&data->buffer);
+	ccs811_set_wakeup(data, false);
+
+	return ret;
 }
 
 static int ccs811_read_raw(struct iio_dev *indio_dev,
@@ -336,6 +357,42 @@ static irqreturn_t ccs811_data_rdy_trigger_poll(int irq, void *private)
 	return IRQ_HANDLED;
 }
 
+static int ccs811_reset(struct i2c_client *client)
+{
+	struct gpio_desc *reset_gpio;
+	int ret;
+
+	reset_gpio = devm_gpiod_get_optional(&client->dev, "reset",
+					     GPIOD_OUT_LOW);
+	if (IS_ERR(reset_gpio)) {
+		dev_err(&client->dev, "Failed to acquire reset gpio\n");
+		return PTR_ERR(reset_gpio);
+	}
+
+	/* Try to reset using nRESET pin if available else do SW reset */
+	if (reset_gpio) {
+		gpiod_set_value(reset_gpio, 1);
+		usleep_range(20, 30);
+		gpiod_set_value(reset_gpio, 0);
+	} else {
+		static const u8 reset_seq[] = {
+			0xFF, 0x11, 0xE5, 0x72, 0x8A,
+		};
+
+		ret = i2c_smbus_write_i2c_block_data(client, CCS811_SW_RESET,
+					     sizeof(reset_seq), reset_seq);
+		if (ret < 0) {
+			dev_err(&client->dev, "Failed to reset sensor\n");
+			return ret;
+		}
+	}
+
+	/* tSTART delay required after reset */
+	usleep_range(1000, 2000);
+
+	return 0;
+}
+
 static int ccs811_probe(struct i2c_client *client,
 			const struct i2c_device_id *id)
 {
@@ -348,6 +405,27 @@ static int ccs811_probe(struct i2c_client *client,
 				     | I2C_FUNC_SMBUS_READ_I2C_BLOCK))
 		return -EOPNOTSUPP;
 
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	data = iio_priv(indio_dev);
+	i2c_set_clientdata(client, indio_dev);
+	data->client = client;
+
+	data->wakeup_gpio = devm_gpiod_get_optional(&client->dev, "wakeup",
+						    GPIOD_OUT_HIGH);
+	if (IS_ERR(data->wakeup_gpio)) {
+		dev_err(&client->dev, "Failed to acquire wakeup gpio\n");
+		return PTR_ERR(data->wakeup_gpio);
+	}
+
+	ccs811_set_wakeup(data, true);
+
+	ret = ccs811_reset(client);
+	if (ret)
+		return ret;
+
 	/* Check hardware id (should be 0x81 for this family of devices) */
 	ret = i2c_smbus_read_byte_data(client, CCS811_HW_ID);
 	if (ret < 0)
@@ -367,17 +445,11 @@ static int ccs811_probe(struct i2c_client *client,
 		return -ENODEV;
 	}
 
-	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
-	if (!indio_dev)
-		return -ENOMEM;
-
 	ret = ccs811_setup(client);
 	if (ret < 0)
 		return ret;
 
-	data = iio_priv(indio_dev);
-	i2c_set_clientdata(client, indio_dev);
-	data->client = client;
+	ccs811_set_wakeup(data, false);
 
 	mutex_init(&data->lock);
 
-- 
2.17.1

[PATCH v2 3/3] iio: chemical: Add OF match table for CCS811 VOC sensor

[mani]

From: Manivannan Sadhasivam <mani@kernel.org>

Add devicetree OF match table support for CCS811 VOC sensor.

Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
---
 drivers/iio/chemical/ccs811.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/iio/chemical/ccs811.c b/drivers/iio/chemical/ccs811.c
index 951358710f64..310e9dedc9ba 100644
--- a/drivers/iio/chemical/ccs811.c
+++ b/drivers/iio/chemical/ccs811.c
@@ -538,9 +538,16 @@ static const struct i2c_device_id ccs811_id[] = {
 };
 MODULE_DEVICE_TABLE(i2c, ccs811_id);
 
+static const struct of_device_id ccs811_dt_ids[] = {
+	{ .compatible = "ams,ccs811" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, ccs811_dt_ids);
+
 static struct i2c_driver ccs811_driver = {
 	.driver = {
 		.name = "ccs811",
+		.of_match_table = ccs811_dt_ids,
 	},
 	.probe = ccs811_probe,
 	.remove = ccs811_remove,
-- 
2.17.1

Re: [PATCH v2 2/3] iio: chemical: Add support for external Reset and Wakeup in CCS811

[Andy Shevchenko]

On Tue, Apr 14, 2020 at 6:34 PM <mani@kernel.org> wrote:
>
> From: Manivannan Sadhasivam <mani@kernel.org>
>
> CCS811 VOC sensor exposes nRESET and nWAKE pins which can be connected
> to GPIO pins of the host controller. These pins can be used to externally
> release the device from reset and also to wake it up before any I2C
> transaction. The initial driver support assumed that the nRESET pin is not
> connected and the nWAKE pin is tied to ground.
>
> This commit improves it by adding support for controlling those two pins
> externally using a host controller. For the case of reset, if the hardware
> reset is not available, the mechanism to do software reset is also added.
>
> As a side effect of doing this, the IIO device allocation needs to be
> slightly moved to top of probe to make use of priv data early.

Thank you for an update, my comments below.

...

> +       reset_gpio = devm_gpiod_get_optional(&client->dev, "reset",
> +                                            GPIOD_OUT_LOW);
> +       if (IS_ERR(reset_gpio)) {

> +               dev_err(&client->dev, "Failed to acquire reset gpio\n");

If it's a deferred probe, it would spam the log.

> +               return PTR_ERR(reset_gpio);
> +       }

...

> +               static const u8 reset_seq[] = {
> +                       0xFF, 0x11, 0xE5, 0x72, 0x8A,
> +               };

I would suggest to comment above from where you got this and the
meaning of the numbers.

...

> +       data->wakeup_gpio = devm_gpiod_get_optional(&client->dev, "wakeup",
> +                                                   GPIOD_OUT_HIGH);
> +       if (IS_ERR(data->wakeup_gpio)) {

> +               dev_err(&client->dev, "Failed to acquire wakeup gpio\n");

Ditto.

> +               return PTR_ERR(data->wakeup_gpio);
> +       }

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v2 3/3] iio: chemical: Add OF match table for CCS811 VOC sensor

[Andy Shevchenko]

On Tue, Apr 14, 2020 at 6:34 PM <mani@kernel.org> wrote:
>
> From: Manivannan Sadhasivam <mani@kernel.org>
>
> Add devicetree OF match table support for CCS811 VOC sensor.
>

This looks good to me. FWIW,
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

> Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
> ---
>  drivers/iio/chemical/ccs811.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/drivers/iio/chemical/ccs811.c b/drivers/iio/chemical/ccs811.c
> index 951358710f64..310e9dedc9ba 100644
> --- a/drivers/iio/chemical/ccs811.c
> +++ b/drivers/iio/chemical/ccs811.c
> @@ -538,9 +538,16 @@ static const struct i2c_device_id ccs811_id[] = {
>  };
>  MODULE_DEVICE_TABLE(i2c, ccs811_id);
>
> +static const struct of_device_id ccs811_dt_ids[] = {
> +       { .compatible = "ams,ccs811" },
> +       { }
> +};
> +MODULE_DEVICE_TABLE(of, ccs811_dt_ids);
> +
>  static struct i2c_driver ccs811_driver = {
>         .driver = {
>                 .name = "ccs811",
> +               .of_match_table = ccs811_dt_ids,
>         },
>         .probe = ccs811_probe,
>         .remove = ccs811_remove,
> --
> 2.17.1
>


-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v2 2/3] iio: chemical: Add support for external Reset and Wakeup in CCS811

[Manivannan Sadhasivam]

On Tue, Apr 14, 2020 at 07:42:24PM +0300, Andy Shevchenko wrote:
> On Tue, Apr 14, 2020 at 6:34 PM <mani@kernel.org> wrote:
> >
> > From: Manivannan Sadhasivam <mani@kernel.org>
> >
> > CCS811 VOC sensor exposes nRESET and nWAKE pins which can be connected
> > to GPIO pins of the host controller. These pins can be used to externally
> > release the device from reset and also to wake it up before any I2C
> > transaction. The initial driver support assumed that the nRESET pin is not
> > connected and the nWAKE pin is tied to ground.
> >
> > This commit improves it by adding support for controlling those two pins
> > externally using a host controller. For the case of reset, if the hardware
> > reset is not available, the mechanism to do software reset is also added.
> >
> > As a side effect of doing this, the IIO device allocation needs to be
> > slightly moved to top of probe to make use of priv data early.
> 
> Thank you for an update, my comments below.
> 
> ...
> 
> > +       reset_gpio = devm_gpiod_get_optional(&client->dev, "reset",
> > +                                            GPIOD_OUT_LOW);
> > +       if (IS_ERR(reset_gpio)) {
> 
> > +               dev_err(&client->dev, "Failed to acquire reset gpio\n");
> 
> If it's a deferred probe, it would spam the log.
> 

Hmm. But error is an error isn't it? Would you recommend doing a debug print
or completely removing the logging?

> > +               return PTR_ERR(reset_gpio);
> > +       }
> 
> ...
> 
> > +               static const u8 reset_seq[] = {
> > +                       0xFF, 0x11, 0xE5, 0x72, 0x8A,
> > +               };
> 
> I would suggest to comment above from where you got this and the
> meaning of the numbers.
> 

The datasheet doesn't specify the meaning of these values. But will add a
comment. Btw, just noticed that 0xFF is not needed and only 4 values are
sufficient for SW reset.

Thanks,
Mani

> ...
> 
> > +       data->wakeup_gpio = devm_gpiod_get_optional(&client->dev, "wakeup",
> > +                                                   GPIOD_OUT_HIGH);
> > +       if (IS_ERR(data->wakeup_gpio)) {
> 
> > +               dev_err(&client->dev, "Failed to acquire wakeup gpio\n");
> 
> Ditto.
> 
> > +               return PTR_ERR(data->wakeup_gpio);
> > +       }
> 
> -- 
> With Best Regards,
> Andy Shevchenko

Re: [PATCH v2 2/3] iio: chemical: Add support for external Reset and Wakeup in CCS811

[Andy Shevchenko]

On Tue, Apr 14, 2020 at 8:06 PM Manivannan Sadhasivam <mani@kernel.org> wrote:
> On Tue, Apr 14, 2020 at 07:42:24PM +0300, Andy Shevchenko wrote:
> > On Tue, Apr 14, 2020 at 6:34 PM <mani@kernel.org> wrote:

...

> > > +       reset_gpio = devm_gpiod_get_optional(&client->dev, "reset",
> > > +                                            GPIOD_OUT_LOW);
> > > +       if (IS_ERR(reset_gpio)) {
> >
> > > +               dev_err(&client->dev, "Failed to acquire reset gpio\n");
> >
> > If it's a deferred probe, it would spam the log.
> >
>
> Hmm. But error is an error isn't it? Would you recommend doing a debug print
> or completely removing the logging?

I would remove completely, but better to wait for Jonathan to comment.
Maybe he prefers something like
  if (err != EPROBE_DEFER)
    dev_err()

> > > +               return PTR_ERR(reset_gpio);
> > > +       }
> >
> > ...
> >
> > > +               static const u8 reset_seq[] = {
> > > +                       0xFF, 0x11, 0xE5, 0x72, 0x8A,
> > > +               };
> >
> > I would suggest to comment above from where you got this and the
> > meaning of the numbers.
> >
>
> The datasheet doesn't specify the meaning of these values. But will add a
> comment.

Thanks!

> Btw, just noticed that 0xFF is not needed and only 4 values are
> sufficient for SW reset.

Better to do exactly what datasheet suggests (in case it's not clear
or deductible what is going on).

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v2 2/3] iio: chemical: Add support for external Reset and Wakeup in CCS811

[Jonathan Cameron]

On Tue, 14 Apr 2020 20:54:49 +0300
Andy Shevchenko <andy.shevchenko@gmail.com> wrote:

> On Tue, Apr 14, 2020 at 8:06 PM Manivannan Sadhasivam <mani@kernel.org> wrote:
> > On Tue, Apr 14, 2020 at 07:42:24PM +0300, Andy Shevchenko wrote:  
> > > On Tue, Apr 14, 2020 at 6:34 PM <mani@kernel.org> wrote:  
> 
> ...
> 
> > > > +       reset_gpio = devm_gpiod_get_optional(&client->dev, "reset",
> > > > +                                            GPIOD_OUT_LOW);
> > > > +       if (IS_ERR(reset_gpio)) {  
> > >  
> > > > +               dev_err(&client->dev, "Failed to acquire reset gpio\n");  
> > >
> > > If it's a deferred probe, it would spam the log.
> > >  
> >
> > Hmm. But error is an error isn't it? Would you recommend doing a debug print
> > or completely removing the logging?  
> 
> I would remove completely, but better to wait for Jonathan to comment.
> Maybe he prefers something like
>   if (err != EPROBE_DEFER)
>     dev_err()

Not fussed.  Either drop it or do the check for defer - one I leave up to the
author.

> 
> > > > +               return PTR_ERR(reset_gpio);
> > > > +       }  
> > >
> > > ...
> > >  
> > > > +               static const u8 reset_seq[] = {
> > > > +                       0xFF, 0x11, 0xE5, 0x72, 0x8A,
> > > > +               };  
> > >
> > > I would suggest to comment above from where you got this and the
> > > meaning of the numbers.
> > >  
> >
> > The datasheet doesn't specify the meaning of these values. But will add a
> > comment.  
> 
> Thanks!
> 
> > Btw, just noticed that 0xFF is not needed and only 4 values are
> > sufficient for SW reset.  
> 
> Better to do exactly what datasheet suggests (in case it's not clear
> or deductible what is going on).
> 

Re: [PATCH v2 2/3] iio: chemical: Add support for external Reset and Wakeup in CCS811

[Manivannan Sadhasivam]

On Tue, Apr 14, 2020 at 07:12:59PM +0100, Jonathan Cameron wrote:
> On Tue, 14 Apr 2020 20:54:49 +0300
> Andy Shevchenko <andy.shevchenko@gmail.com> wrote:
> 
> > On Tue, Apr 14, 2020 at 8:06 PM Manivannan Sadhasivam <mani@kernel.org> wrote:
> > > On Tue, Apr 14, 2020 at 07:42:24PM +0300, Andy Shevchenko wrote:  
> > > > On Tue, Apr 14, 2020 at 6:34 PM <mani@kernel.org> wrote:  
> > 
> > ...
> > 
> > > > > +       reset_gpio = devm_gpiod_get_optional(&client->dev, "reset",
> > > > > +                                            GPIOD_OUT_LOW);
> > > > > +       if (IS_ERR(reset_gpio)) {  
> > > >  
> > > > > +               dev_err(&client->dev, "Failed to acquire reset gpio\n");  
> > > >
> > > > If it's a deferred probe, it would spam the log.
> > > >  
> > >
> > > Hmm. But error is an error isn't it? Would you recommend doing a debug print
> > > or completely removing the logging?  
> > 
> > I would remove completely, but better to wait for Jonathan to comment.
> > Maybe he prefers something like
> >   if (err != EPROBE_DEFER)
> >     dev_err()
> 
> Not fussed.  Either drop it or do the check for defer - one I leave up to the
> author.
> 

Okay, will just drop it.

Thanks,
Mani

> > 
> > > > > +               return PTR_ERR(reset_gpio);
> > > > > +       }  
> > > >
> > > > ...
> > > >  
> > > > > +               static const u8 reset_seq[] = {
> > > > > +                       0xFF, 0x11, 0xE5, 0x72, 0x8A,
> > > > > +               };  
> > > >
> > > > I would suggest to comment above from where you got this and the
> > > > meaning of the numbers.
> > > >  
> > >
> > > The datasheet doesn't specify the meaning of these values. But will add a
> > > comment.  
> > 
> > Thanks!
> > 
> > > Btw, just noticed that 0xFF is not needed and only 4 values are
> > > sufficient for SW reset.  
> > 
> > Better to do exactly what datasheet suggests (in case it's not clear
> > or deductible what is going on).
> > 
>