Add Reset and Wakeup support for CCS811

From: Manivannan Sadhasivam <[email protected]>

This commit adds devicetree binding for AMS CCS811 VOC sensor.

Signed-off-by Manivannan Sadhasivam <[email protected]>

---
 .../bindings/iio/chemical/ams,ccs811.yaml     | 51 +++++++++++++++++++
 1 file changed, 51 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/chemical/ams,ccs811.yaml

Documentation/devicetree/bindings/iio/chemical/ams,ccs811.yaml new file +24 -0

new file mode 100644
index 000000000000..5cb068666a3e
@@ -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 <[email protected]>
+
+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.

Quoted 40 lines · On Wed, Apr 15, 2020 at 12:19:28AM +0530, [email protected] wrote:

From: Manivannan Sadhasivam <[email protected]>

This commit adds devicetree binding for AMS CCS811 VOC sensor.

Signed-off-by Manivannan Sadhasivam <[email protected]>

---
 .../bindings/iio/chemical/ams,ccs811.yaml     | 51 +++++++++++++++++++
 1 file changed, 51 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/chemical/ams,ccs811.yaml

Documentation/devicetree/bindings/iio/chemical/ams,ccs811.yaml new file +24 -0

new file mode 100644
index 000000000000..5cb068666a3e
@@ -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 <[email protected]>
+
+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.

Documentation/devicetree/bindings/iio/chemical/ams,ccs811.yaml line 34

Quoted 10 lines

Documentation/devicetree/bindings/iio/chemical/ams,ccs811.yaml new file +10 -0

+    maxItems: 1
+
+  wakeup-gpios:
+    description: GPIO connected to the nWAKE line. This is an active low
+                 input to CCS811.
+    maxItems: 1
+
+required:
+  - compatible
+  - reg

Add:

additionalProperties: false

With that,

Reviewed-by Rob Herring <[email protected]>

Quoted 54 lines · Rob Herring

Quoted 40 lines · On Wed, Apr 15, 2020 at 12:19:28AM +0530, [email protected] wrote:

From: Manivannan Sadhasivam <[email protected]>

This commit adds devicetree binding for AMS CCS811 VOC sensor.

Signed-off-by Manivannan Sadhasivam <[email protected]>

---
 .../bindings/iio/chemical/ams,ccs811.yaml     | 51 +++++++++++++++++++
 1 file changed, 51 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/chemical/ams,ccs811.yaml

Documentation/devicetree/bindings/iio/chemical/ams,ccs811.yaml new file +24 -0

new file mode 100644
index 000000000000..5cb068666a3e
@@ -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 <[email protected]>
+
+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.

Documentation/devicetree/bindings/iio/chemical/ams,ccs811.yaml line 34

Quoted 10 lines

Documentation/devicetree/bindings/iio/chemical/ams,ccs811.yaml new file +10 -0

+    maxItems: 1
+
+  wakeup-gpios:
+    description: GPIO connected to the nWAKE line. This is an active low
+                 input to CCS811.
+    maxItems: 1
+
+required:
+  - compatible
+  - reg  

Add:

Quoted 2 lines

additionalProperties: false

Hi Jonathan,

Do you want me to spin another series or you can add it while applying?

Thanks,
Mani

Quoted 3 lines

With that,

Reviewed-by Rob Herring <[email protected]>

From: Manivannan Sadhasivam <[email protected]>

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 <[email protected]>

---
 drivers/iio/chemical/ccs811.c | 105 ++++++++++++++++++++++++++++++----
 1 file changed, 94 insertions(+), 11 deletions(-)

drivers/iio/chemical/ccs811.c +94 -12

index 2ebdfc35bcda..1500e4b0dfbd 100644
@@ -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 +357,45 @@ 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))
+               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 {
+               /*
+                * As per the datasheet, this sequence of values needs to be
+                * written to the SW_RESET register for triggering the soft
+                * reset in the device and placing it in boot mode.
+                */
+               static const u8 reset_seq[] = {
+                       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)
 {

@@ -348,36 +408,59 @@ 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))
+               return PTR_ERR(data->wakeup_gpio);
+
+       ccs811_set_wakeup(data, true);
+
+       ret = ccs811_reset(client);
+       if (ret) {
+               ccs811_set_wakeup(data, false);
+               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)
+       if (ret < 0) {
+               ccs811_set_wakeup(data, false);
                return ret;
+       }
 
        if (ret != CCS811_HW_ID_VALUE) {
                dev_err(&client->dev, "hardware id doesn't match CCS81x\n");
+               ccs811_set_wakeup(data, false);
                return -ENODEV;
        }
 
        ret = i2c_smbus_read_byte_data(client, CCS811_HW_VERSION);
-       if (ret < 0)
+       if (ret < 0) {
+               ccs811_set_wakeup(data, false);
                return ret;
+       }
 
        if ((ret & CCS811_HW_VERSION_MASK) != CCS811_HW_VERSION_VALUE) {
                dev_err(&client->dev, "no CCS811 sensor\n");
+               ccs811_set_wakeup(data, false);
                return -ENODEV;
        }
 
-       indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
-       if (!indio_dev)
-               return -ENOMEM;
-
        ret = ccs811_setup(client);
-       if (ret < 0)
+       if (ret < 0) {
+               ccs811_set_wakeup(data, false);
                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

From: Manivannan Sadhasivam <[email protected]>

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 v3:

* Added ccs811_set_wake(false) to all error paths before calling it actually
* Added Andy's reviewed-by tag
* Added comment for reset procedure and dropped error print for gpio request

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                 | 112 ++++++++++++++++--
 2 files changed, 152 insertions(+), 11 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/iio/chemical/ams,ccs811.yaml

From: Manivannan Sadhasivam <[email protected]>

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 v3:

* Added ccs811_set_wake(false) to all error paths before calling it actually
* Added Andy's reviewed-by tag
* Added comment for reset procedure and dropped error print for gpio request

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                 | 112 ++++++++++++++++--
 2 files changed, 152 insertions(+), 11 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/iio/chemical/ams,ccs811.yaml