[PATCH 0/7] iio: mlx90614 enhancements

[PATCH 0/7] iio: mlx90614 enhancements

[Vianney le Clément de Saint-Marcq]

This set of patches adds the following additional features to the
mlx90614 temperature sensor driver.

* Processed temperature output (patch 3)
* Support for the dual IR sensor model (patch 4)
* EEPROM configuration tuning (patch 5)
* Power management (patch 6)
* Raw IR value access (RFC, patch 7)

The changes have been split into 7 patches to ease code review.
Patches 1 and 2 contain mandatory symbol definitions.
Patches 3-7 implement the additional features and are mostly independent
from each other.  If some features are not desired, the corresponding
patches can be left out.

Perhaps the most tricky part is the power management implemented by
patch 6, as it involves an extra GPIO messing with the SDA line in order
to wake up the sensor.  See the commit message for details.

Patch 6 introduces device tree bindings and is the only one sent to the
devicetree list.

Vianney le Clément de Saint-Marcq (7):
  iio: mlx90614: Refactor register symbols
  iio: mlx90614: Add symbols for accessible registers
  iio: mlx90614: Add processed temperature output
  iio: mlx90614: Support devices with dual IR sensor
  iio: mlx90614: Allow tuning EEPROM configuration
  iio: mlx90614: Add power management
  iio: mlx90614: Provide raw IR value for object channels

 .../bindings/iio/temperature/mlx90614.txt          |  24 +
 .../devicetree/bindings/vendor-prefixes.txt        |   1 +
 drivers/iio/temperature/mlx90614.c                 | 574 ++++++++++++++++++++-
 3 files changed, 580 insertions(+), 19 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/iio/temperature/mlx90614.txt

-- 
2.3.0

[PATCH 6/7] iio: mlx90614: Add power management

[Vianney le Clément de Saint-Marcq]

Add support for system sleep and runtime power management.

To wake up the device, the SDA line should be held low for at least 33ms
while SCL is high.  As this is not possible using the i2c API (and not
supported by all i2c adapters), a GPIO connected to the SDA line is
needed.  The GPIO is named "wakeup" and can be specified in a device
tree with the "wakeup-gpios" binding.

If the wake-up GPIO is not given, disable power management for the
device.  Entering sleep requires an SMBus byte access, hence power
management is also disabled if byte access is not supported by the
adapter.

Signed-off-by: Vianney le Clément de Saint-Marcq <vianney.leclement@essensium.com>
Cc: Arnout Vandecappelle (Essensium/Mind) <arnout-agwphqFHkxc@public.gmane.org>

---

The default autosleep delay (5s) is chosen arbitrarily, trying to take
into account the long startup time (250ms).  Feel free to change it to
another value if you think it is saner.
---
 .../bindings/iio/temperature/mlx90614.txt          |  24 ++
 .../devicetree/bindings/vendor-prefixes.txt        |   1 +
 drivers/iio/temperature/mlx90614.c                 | 244 ++++++++++++++++++++-
 3 files changed, 267 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/iio/temperature/mlx90614.txt

diff --git a/Documentation/devicetree/bindings/iio/temperature/mlx90614.txt b/Documentation/devicetree/bindings/iio/temperature/mlx90614.txt
new file mode 100644
index 0000000..9be57b0
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/temperature/mlx90614.txt
@@ -0,0 +1,24 @@
+* Melexis MLX90614 contactless IR temperature sensor
+
+http://melexis.com/Infrared-Thermometer-Sensors/Infrared-Thermometer-Sensors/MLX90614-615.aspx
+
+Required properties:
+
+  - compatible: should be "melexis,mlx90614"
+  - reg: the I2C address of the sensor
+
+Optional properties:
+
+  - wakeup-gpios: device tree identifier of the GPIO connected to the SDA line
+      to hold low in order to wake up the device.  In normal operation, the
+      GPIO is set as input and will not interfere in I2C communication.  There
+      is no need for a GPIO driving the SCL line.  If no GPIO is given, power
+      management is disabled.
+
+Example:
+
+mlx90614@5a {
+	compatible = "melexis,mlx90614";
+	reg = <0x5a>;
+	wakeup-gpios = <&gpio0 2 GPIO_ACTIVE_HIGH>;
+};
diff --git a/Documentation/devicetree/bindings/vendor-prefixes.txt b/Documentation/devicetree/bindings/vendor-prefixes.txt
index 389ca13..ceacc40 100644
--- a/Documentation/devicetree/bindings/vendor-prefixes.txt
+++ b/Documentation/devicetree/bindings/vendor-prefixes.txt
@@ -108,6 +108,7 @@ lltc	Linear Technology Corporation
 marvell	Marvell Technology Group Ltd.
 maxim	Maxim Integrated Products
 mediatek	MediaTek Inc.
+melexis	Melexis N.V.
 merrii	Merrii Technology Co., Ltd.
 micrel	Micrel Inc.
 microchip	Microchip Technology Inc.
diff --git a/drivers/iio/temperature/mlx90614.c b/drivers/iio/temperature/mlx90614.c
index ab98fb6..49c517a 100644
--- a/drivers/iio/temperature/mlx90614.c
+++ b/drivers/iio/temperature/mlx90614.c
@@ -12,13 +12,22 @@
  *
  * (7-bit I2C slave address 0x5a, 100KHz bus speed only!)
  *
- * TODO: sleep mode
+ * To wake up from sleep mode, the SDA line must be held low while SCL is high
+ * for at least 33ms.  This is achieved with an extra GPIO that can be connected
+ * directly to the SDA line.  In normal operation, the GPIO is set as input and
+ * will not interfere in I2C communication.  While the GPIO is driven low, the
+ * i2c adapter is locked since it cannot be used by other clients.  The SCL line
+ * always has a pull-up so we do not need an extra GPIO to drive it high.  If
+ * the "wakeup" GPIO is not given, power management will be disabled.
  */
 
 #include <linux/err.h>
 #include <linux/i2c.h>
 #include <linux/module.h>
 #include <linux/delay.h>
+#include <linux/jiffies.h>
+#include <linux/gpio/consumer.h>
+#include <linux/pm_runtime.h>
 
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
@@ -53,9 +62,13 @@
 #define MLX90614_TIMING_WAKEUP 34 /* time to hold SDA low for wake-up */
 #define MLX90614_TIMING_STARTUP 250 /* time before first data after wake-up */
 
+#define MLX90614_AUTOSLEEP_DELAY 5000 /* default autosleep delay */
+
 struct mlx90614_data {
 	struct i2c_client *client;
 	struct mutex lock; /* for EEPROM access only */
+	struct gpio_desc *wakeup_gpio; /* NULL to disable sleep/wake-up */
+	unsigned long ready_timestamp; /* in jiffies */
 };
 
 /*
@@ -96,6 +109,52 @@ static s32 mlx90614_write_word(const struct i2c_client *client, u8 command,
 	return ret;
 }
 
+#ifdef CONFIG_PM
+/*
+ * If @startup is true, make sure MLX90614_TIMING_STARTUP ms have elapsed since
+ * the last wake-up.  This is normally only needed to get a valid temperature
+ * reading.  EEPROM access does not need such delay.
+ */
+static void mlx90614_power_get(struct mlx90614_data *data, bool startup)
+{
+	unsigned long now;
+
+	if (!data->wakeup_gpio)
+		return;
+
+	pm_runtime_get_sync(&data->client->dev);
+
+	if (startup) {
+		/*
+		 * If the process requesting the temperature gets killed when
+		 * waiting here, it does not matter whether the reading is
+		 * valid.  Hence, the sleep is interruptible.
+		 */
+		now = jiffies;
+		if (time_before(now, data->ready_timestamp))
+			msleep_interruptible(jiffies_to_msecs(
+						data->ready_timestamp - now));
+	}
+}
+
+static void mlx90614_power_put(struct mlx90614_data *data)
+{
+	if (!data->wakeup_gpio)
+		return;
+
+	pm_runtime_mark_last_busy(&data->client->dev);
+	pm_runtime_put_autosuspend(&data->client->dev);
+}
+#else
+static inline void mlx90614_power_get(struct mlx90614_data *data, bool startup)
+{
+}
+
+static inline void mlx90614_power_put(struct mlx90614_data *data)
+{
+}
+#endif
+
 static int mlx90614_read_raw(struct iio_dev *indio_dev,
 			    struct iio_chan_spec const *channel, int *val,
 			    int *val2, long mask)
@@ -127,7 +186,10 @@ static int mlx90614_read_raw(struct iio_dev *indio_dev,
 			return -EINVAL;
 		}
 
+		mlx90614_power_get(data, true);
 		ret = i2c_smbus_read_word_data(data->client, cmd);
+		mlx90614_power_put(data);
+
 		if (ret < 0)
 			return ret;
 
@@ -160,9 +222,11 @@ static ssize_t mlx90614_show_emissivity(struct device *dev,
 	struct mlx90614_data *data = iio_priv(indio_dev);
 	s32 ret;
 
+	mlx90614_power_get(data, false);
 	mutex_lock(&data->lock);
 	ret = i2c_smbus_read_word_data(data->client, MLX90614_EMISSIVITY);
 	mutex_unlock(&data->lock);
+	mlx90614_power_put(data);
 
 	if (ret < 0)
 		return ret;
@@ -182,9 +246,11 @@ static ssize_t mlx90614_store_emissivity(struct device *dev,
 	if (kstrtou16(buf, 0, &val))
 		return -EINVAL;
 
+	mlx90614_power_get(data, false);
 	mutex_lock(&data->lock);
 	ret = mlx90614_write_word(data->client, MLX90614_EMISSIVITY, val);
 	mutex_unlock(&data->lock);
+	mlx90614_power_put(data);
 
 	if (ret < 0)
 		return ret;
@@ -203,9 +269,11 @@ static ssize_t mlx90614_show_config(struct device *dev,
 	u16 shift = indio_attr->address >> 16;
 	s32 ret;
 
+	mlx90614_power_get(data, false);
 	mutex_lock(&data->lock);
 	ret = i2c_smbus_read_word_data(data->client, MLX90614_CONFIG);
 	mutex_unlock(&data->lock);
+	mlx90614_power_put(data);
 
 	if (ret < 0)
 		return ret;
@@ -230,6 +298,7 @@ static ssize_t mlx90614_store_config(struct device *dev,
 	if (kstrtou16(buf, 0, &val) || val != (val & (mask >> shift)))
 		return -EINVAL;
 
+	mlx90614_power_get(data, false);
 	mutex_lock(&data->lock);
 
 	ret = i2c_smbus_read_word_data(data->client, MLX90614_CONFIG);
@@ -241,6 +310,7 @@ static ssize_t mlx90614_store_config(struct device *dev,
 
 out:
 	mutex_unlock(&data->lock);
+	mlx90614_power_put(data);
 
 	if (ret < 0)
 		return ret;
@@ -320,6 +390,98 @@ static const struct iio_info mlx90614_info = {
 	.driver_module = THIS_MODULE,
 };
 
+#ifdef CONFIG_PM
+static int mlx90614_sleep(struct mlx90614_data *data)
+{
+	s32 ret;
+
+	if (!data->wakeup_gpio) {
+		dev_dbg(&data->client->dev, "Sleep disabled");
+		return -ENOSYS;
+	}
+
+	dev_dbg(&data->client->dev, "Requesting sleep");
+
+	mutex_lock(&data->lock);
+	ret = i2c_smbus_xfer(data->client->adapter, data->client->addr,
+			     data->client->flags | I2C_CLIENT_PEC,
+			     I2C_SMBUS_WRITE, MLX90614_OP_SLEEP,
+			     I2C_SMBUS_BYTE, NULL);
+	mutex_unlock(&data->lock);
+
+	return ret;
+}
+
+static int mlx90614_wakeup(struct mlx90614_data *data)
+{
+	if (!data->wakeup_gpio) {
+		dev_dbg(&data->client->dev, "Wake-up disabled");
+		return -ENOSYS;
+	}
+
+	dev_dbg(&data->client->dev, "Requesting wake-up");
+
+	i2c_lock_adapter(data->client->adapter);
+	gpiod_direction_output(data->wakeup_gpio, 0);
+	msleep(MLX90614_TIMING_WAKEUP);
+	gpiod_direction_input(data->wakeup_gpio);
+	i2c_unlock_adapter(data->client->adapter);
+
+	data->ready_timestamp = jiffies +
+			msecs_to_jiffies(MLX90614_TIMING_STARTUP);
+
+	/*
+	 * Quirk: the i2c controller may get confused right after the
+	 * wake-up signal has been sent.  As a workaround, do a dummy read.
+	 * If the read fails, the controller will probably be reset so that
+	 * further reads will work.
+	 */
+	i2c_smbus_read_word_data(data->client, MLX90614_CONFIG);
+
+	return 0;
+}
+
+/* Return wake-up GPIO or NULL if sleep functionality should be disabled. */
+static struct gpio_desc *mlx90614_probe_wakeup(struct i2c_client *client)
+{
+	struct gpio_desc *gpio;
+
+	if (!i2c_check_functionality(client->adapter,
+						I2C_FUNC_SMBUS_WRITE_BYTE)) {
+		dev_info(&client->dev,
+			 "i2c adapter does not support SMBUS_WRITE_BYTE, sleep disabled");
+		return NULL;
+	}
+
+	gpio = devm_gpiod_get_optional(&client->dev, "wakeup", GPIOD_IN);
+
+	if (IS_ERR(gpio)) {
+		dev_warn(&client->dev,
+			 "gpio acquisition failed with error %ld, sleep disabled",
+			 PTR_ERR(gpio));
+		return NULL;
+	} else if (!gpio) {
+		dev_info(&client->dev,
+			 "wakeup-gpio not found, sleep disabled");
+	}
+
+	return gpio;
+}
+#else
+static inline int mlx90614_sleep(struct mlx90614_data *data)
+{
+	return -ENOSYS;
+}
+static inline int mlx90614_wakeup(struct mlx90614_data *data)
+{
+	return -ENOSYS;
+}
+static inline struct gpio_desc *mlx90614_probe_wakeup(struct i2c_client *client)
+{
+	return NULL;
+}
+#endif
+
 /* Return 0 for single sensor, 1 for dual sensor, <0 on error. */
 static int mlx90614_probe_model(struct i2c_client *client)
 {
@@ -351,6 +513,9 @@ static int mlx90614_probe(struct i2c_client *client,
 	i2c_set_clientdata(client, indio_dev);
 	data->client = client;
 	mutex_init(&data->lock);
+	data->wakeup_gpio = mlx90614_probe_wakeup(client);
+
+	mlx90614_wakeup(data);
 
 	indio_dev->dev.parent = &client->dev;
 	indio_dev->name = id->name;
@@ -373,12 +538,30 @@ static int mlx90614_probe(struct i2c_client *client,
 		return ret;
 	}
 
+	if (data->wakeup_gpio) {
+		pm_runtime_set_autosuspend_delay(&client->dev,
+						 MLX90614_AUTOSLEEP_DELAY);
+		pm_runtime_use_autosuspend(&client->dev);
+		pm_runtime_set_active(&client->dev);
+		pm_runtime_enable(&client->dev);
+	}
+
 	return iio_device_register(indio_dev);
 }
 
 static int mlx90614_remove(struct i2c_client *client)
 {
-	iio_device_unregister(i2c_get_clientdata(client));
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+	struct mlx90614_data *data = iio_priv(indio_dev);
+
+	if (data->wakeup_gpio) {
+		pm_runtime_disable(&client->dev);
+		if (!pm_runtime_status_suspended(&client->dev))
+			mlx90614_sleep(data);
+		pm_runtime_set_suspended(&client->dev);
+	}
+
+	iio_device_unregister(indio_dev);
 
 	return 0;
 }
@@ -389,10 +572,67 @@ static const struct i2c_device_id mlx90614_id[] = {
 };
 MODULE_DEVICE_TABLE(i2c, mlx90614_id);
 
+#ifdef CONFIG_PM_SLEEP
+static int mlx90614_pm_suspend(struct device *dev)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
+	struct mlx90614_data *data = iio_priv(indio_dev);
+
+	if (data->wakeup_gpio && pm_runtime_active(dev))
+		return mlx90614_sleep(data);
+
+	return 0;
+}
+
+static int mlx90614_pm_resume(struct device *dev)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
+	struct mlx90614_data *data = iio_priv(indio_dev);
+	int err;
+
+	if (data->wakeup_gpio) {
+		err = mlx90614_wakeup(data);
+		if (err < 0)
+			return err;
+
+		pm_runtime_disable(dev);
+		pm_runtime_set_active(dev);
+		pm_runtime_enable(dev);
+	}
+
+	return 0;
+}
+#endif
+
+#ifdef CONFIG_PM
+static int mlx90614_pm_runtime_suspend(struct device *dev)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
+	struct mlx90614_data *data = iio_priv(indio_dev);
+
+	return mlx90614_sleep(data);
+}
+
+static int mlx90614_pm_runtime_resume(struct device *dev)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
+	struct mlx90614_data *data = iio_priv(indio_dev);
+
+	return mlx90614_wakeup(data);
+}
+#endif
+
+static const struct dev_pm_ops mlx90614_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(mlx90614_pm_suspend, mlx90614_pm_resume)
+	SET_RUNTIME_PM_OPS(mlx90614_pm_runtime_suspend,
+			   mlx90614_pm_runtime_resume, NULL)
+};
+
 static struct i2c_driver mlx90614_driver = {
 	.driver = {
 		.name	= "mlx90614",
 		.owner	= THIS_MODULE,
+		.pm	= &mlx90614_pm_ops,
 	},
 	.probe = mlx90614_probe,
 	.remove = mlx90614_remove,
-- 
2.3.0

Re: [PATCH 6/7] iio: mlx90614: Add power management

[Jonathan Cameron]

On 25/02/15 15:55, Vianney le Clément de Saint-Marcq wrote:
> Add support for system sleep and runtime power management.
> 
> To wake up the device, the SDA line should be held low for at least 33ms
> while SCL is high.  As this is not possible using the i2c API (and not
> supported by all i2c adapters), a GPIO connected to the SDA line is
> needed.  The GPIO is named "wakeup" and can be specified in a device
> tree with the "wakeup-gpios" binding.
Needs some i2c specialist input on this!  As you mentioned it is liable
to be controversial.  Wolfram, is this a one off special or do
any other devices do this sort of magic?
> 
> If the wake-up GPIO is not given, disable power management for the
> device.  Entering sleep requires an SMBus byte access, hence power
> management is also disabled if byte access is not supported by the
> adapter.
> 
> Signed-off-by: Vianney le Clément de Saint-Marcq <vianney.leclement-buIOx9BAs4sybS5Ee8rs3A@public.gmane.org>
> Cc: Arnout Vandecappelle (Essensium/Mind) <arnout-agwphqFHkxc@public.gmane.org>
> 
> ---
> 
> The default autosleep delay (5s) is chosen arbitrarily, trying to take
> into account the long startup time (250ms).  Feel free to change it to
> another value if you think it is saner.
> ---
>  .../bindings/iio/temperature/mlx90614.txt          |  24 ++
>  .../devicetree/bindings/vendor-prefixes.txt        |   1 +
>  drivers/iio/temperature/mlx90614.c                 | 244 ++++++++++++++++++++-
>  3 files changed, 267 insertions(+), 2 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/iio/temperature/mlx90614.txt
> 
> diff --git a/Documentation/devicetree/bindings/iio/temperature/mlx90614.txt b/Documentation/devicetree/bindings/iio/temperature/mlx90614.txt
> new file mode 100644
> index 0000000..9be57b0
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/temperature/mlx90614.txt
> @@ -0,0 +1,24 @@
> +* Melexis MLX90614 contactless IR temperature sensor
> +
> +http://melexis.com/Infrared-Thermometer-Sensors/Infrared-Thermometer-Sensors/MLX90614-615.aspx
> +
> +Required properties:
> +
> +  - compatible: should be "melexis,mlx90614"
> +  - reg: the I2C address of the sensor
> +
> +Optional properties:
> +
> +  - wakeup-gpios: device tree identifier of the GPIO connected to the SDA line
> +      to hold low in order to wake up the device.  In normal operation, the
> +      GPIO is set as input and will not interfere in I2C communication.  There
> +      is no need for a GPIO driving the SCL line.  If no GPIO is given, power
> +      management is disabled.
> +
> +Example:
> +
> +mlx90614@5a {
> +	compatible = "melexis,mlx90614";
> +	reg = <0x5a>;
> +	wakeup-gpios = <&gpio0 2 GPIO_ACTIVE_HIGH>;
> +};
> diff --git a/Documentation/devicetree/bindings/vendor-prefixes.txt b/Documentation/devicetree/bindings/vendor-prefixes.txt
> index 389ca13..ceacc40 100644
> --- a/Documentation/devicetree/bindings/vendor-prefixes.txt
> +++ b/Documentation/devicetree/bindings/vendor-prefixes.txt
> @@ -108,6 +108,7 @@ lltc	Linear Technology Corporation
>  marvell	Marvell Technology Group Ltd.
>  maxim	Maxim Integrated Products
>  mediatek	MediaTek Inc.
> +melexis	Melexis N.V.
>  merrii	Merrii Technology Co., Ltd.
>  micrel	Micrel Inc.
>  microchip	Microchip Technology Inc.
> diff --git a/drivers/iio/temperature/mlx90614.c b/drivers/iio/temperature/mlx90614.c
> index ab98fb6..49c517a 100644
> --- a/drivers/iio/temperature/mlx90614.c
> +++ b/drivers/iio/temperature/mlx90614.c
> @@ -12,13 +12,22 @@
>   *
>   * (7-bit I2C slave address 0x5a, 100KHz bus speed only!)
>   *
> - * TODO: sleep mode
> + * To wake up from sleep mode, the SDA line must be held low while SCL is high
> + * for at least 33ms.  This is achieved with an extra GPIO that can be connected
> + * directly to the SDA line.  In normal operation, the GPIO is set as input and
> + * will not interfere in I2C communication.  While the GPIO is driven low, the
> + * i2c adapter is locked since it cannot be used by other clients.  The SCL line
> + * always has a pull-up so we do not need an extra GPIO to drive it high.  If
> + * the "wakeup" GPIO is not given, power management will be disabled.
>   */
>  
>  #include <linux/err.h>
>  #include <linux/i2c.h>
>  #include <linux/module.h>
>  #include <linux/delay.h>
> +#include <linux/jiffies.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/pm_runtime.h>
>  
>  #include <linux/iio/iio.h>
>  #include <linux/iio/sysfs.h>
> @@ -53,9 +62,13 @@
>  #define MLX90614_TIMING_WAKEUP 34 /* time to hold SDA low for wake-up */
>  #define MLX90614_TIMING_STARTUP 250 /* time before first data after wake-up */
>  
> +#define MLX90614_AUTOSLEEP_DELAY 5000 /* default autosleep delay */
> +
>  struct mlx90614_data {
>  	struct i2c_client *client;
>  	struct mutex lock; /* for EEPROM access only */
> +	struct gpio_desc *wakeup_gpio; /* NULL to disable sleep/wake-up */
> +	unsigned long ready_timestamp; /* in jiffies */
>  };
>  
>  /*
> @@ -96,6 +109,52 @@ static s32 mlx90614_write_word(const struct i2c_client *client, u8 command,
>  	return ret;
>  }
>  
> +#ifdef CONFIG_PM
> +/*
> + * If @startup is true, make sure MLX90614_TIMING_STARTUP ms have elapsed since
> + * the last wake-up.  This is normally only needed to get a valid temperature
> + * reading.  EEPROM access does not need such delay.
> + */
> +static void mlx90614_power_get(struct mlx90614_data *data, bool startup)
> +{
> +	unsigned long now;
> +
> +	if (!data->wakeup_gpio)
> +		return;
> +
> +	pm_runtime_get_sync(&data->client->dev);
> +
> +	if (startup) {
> +		/*
> +		 * If the process requesting the temperature gets killed when
> +		 * waiting here, it does not matter whether the reading is
> +		 * valid.  Hence, the sleep is interruptible.
> +		 */
> +		now = jiffies;
> +		if (time_before(now, data->ready_timestamp))
> +			msleep_interruptible(jiffies_to_msecs(
> +						data->ready_timestamp - now));
> +	}
> +}
> +
> +static void mlx90614_power_put(struct mlx90614_data *data)
> +{
> +	if (!data->wakeup_gpio)
> +		return;
> +
> +	pm_runtime_mark_last_busy(&data->client->dev);
> +	pm_runtime_put_autosuspend(&data->client->dev);
> +}
> +#else
> +static inline void mlx90614_power_get(struct mlx90614_data *data, bool startup)
> +{
> +}
> +
> +static inline void mlx90614_power_put(struct mlx90614_data *data)
> +{
> +}
> +#endif
> +
>  static int mlx90614_read_raw(struct iio_dev *indio_dev,
>  			    struct iio_chan_spec const *channel, int *val,
>  			    int *val2, long mask)
> @@ -127,7 +186,10 @@ static int mlx90614_read_raw(struct iio_dev *indio_dev,
>  			return -EINVAL;
>  		}
>  
> +		mlx90614_power_get(data, true);
>  		ret = i2c_smbus_read_word_data(data->client, cmd);
> +		mlx90614_power_put(data);
> +
>  		if (ret < 0)
>  			return ret;
>  
> @@ -160,9 +222,11 @@ static ssize_t mlx90614_show_emissivity(struct device *dev,
>  	struct mlx90614_data *data = iio_priv(indio_dev);
>  	s32 ret;
>  
> +	mlx90614_power_get(data, false);
>  	mutex_lock(&data->lock);
>  	ret = i2c_smbus_read_word_data(data->client, MLX90614_EMISSIVITY);
>  	mutex_unlock(&data->lock);
> +	mlx90614_power_put(data);
>  
>  	if (ret < 0)
>  		return ret;
> @@ -182,9 +246,11 @@ static ssize_t mlx90614_store_emissivity(struct device *dev,
>  	if (kstrtou16(buf, 0, &val))
>  		return -EINVAL;
>  
> +	mlx90614_power_get(data, false);
>  	mutex_lock(&data->lock);
>  	ret = mlx90614_write_word(data->client, MLX90614_EMISSIVITY, val);
>  	mutex_unlock(&data->lock);
> +	mlx90614_power_put(data);
>  
>  	if (ret < 0)
>  		return ret;
> @@ -203,9 +269,11 @@ static ssize_t mlx90614_show_config(struct device *dev,
>  	u16 shift = indio_attr->address >> 16;
>  	s32 ret;
>  
> +	mlx90614_power_get(data, false);
>  	mutex_lock(&data->lock);
>  	ret = i2c_smbus_read_word_data(data->client, MLX90614_CONFIG);
>  	mutex_unlock(&data->lock);
> +	mlx90614_power_put(data);
>  
>  	if (ret < 0)
>  		return ret;
> @@ -230,6 +298,7 @@ static ssize_t mlx90614_store_config(struct device *dev,
>  	if (kstrtou16(buf, 0, &val) || val != (val & (mask >> shift)))
>  		return -EINVAL;
>  
> +	mlx90614_power_get(data, false);
>  	mutex_lock(&data->lock);
>  
>  	ret = i2c_smbus_read_word_data(data->client, MLX90614_CONFIG);
> @@ -241,6 +310,7 @@ static ssize_t mlx90614_store_config(struct device *dev,
>  
>  out:
>  	mutex_unlock(&data->lock);
> +	mlx90614_power_put(data);
>  
>  	if (ret < 0)
>  		return ret;
> @@ -320,6 +390,98 @@ static const struct iio_info mlx90614_info = {
>  	.driver_module = THIS_MODULE,
>  };
>  
> +#ifdef CONFIG_PM
> +static int mlx90614_sleep(struct mlx90614_data *data)
> +{
> +	s32 ret;
> +
> +	if (!data->wakeup_gpio) {
> +		dev_dbg(&data->client->dev, "Sleep disabled");
> +		return -ENOSYS;
> +	}
> +
> +	dev_dbg(&data->client->dev, "Requesting sleep");
> +
> +	mutex_lock(&data->lock);
> +	ret = i2c_smbus_xfer(data->client->adapter, data->client->addr,
> +			     data->client->flags | I2C_CLIENT_PEC,
> +			     I2C_SMBUS_WRITE, MLX90614_OP_SLEEP,
> +			     I2C_SMBUS_BYTE, NULL);
> +	mutex_unlock(&data->lock);
> +
> +	return ret;
> +}
> +
> +static int mlx90614_wakeup(struct mlx90614_data *data)
> +{
> +	if (!data->wakeup_gpio) {
> +		dev_dbg(&data->client->dev, "Wake-up disabled");
> +		return -ENOSYS;
> +	}
> +
> +	dev_dbg(&data->client->dev, "Requesting wake-up");
> +
> +	i2c_lock_adapter(data->client->adapter);
> +	gpiod_direction_output(data->wakeup_gpio, 0);
> +	msleep(MLX90614_TIMING_WAKEUP);
> +	gpiod_direction_input(data->wakeup_gpio);
> +	i2c_unlock_adapter(data->client->adapter);
> +
> +	data->ready_timestamp = jiffies +
> +			msecs_to_jiffies(MLX90614_TIMING_STARTUP);
> +
> +	/*
> +	 * Quirk: the i2c controller may get confused right after the
> +	 * wake-up signal has been sent.  As a workaround, do a dummy read.
> +	 * If the read fails, the controller will probably be reset so that
> +	 * further reads will work.
> +	 */
> +	i2c_smbus_read_word_data(data->client, MLX90614_CONFIG);
> +
> +	return 0;
> +}
> +
> +/* Return wake-up GPIO or NULL if sleep functionality should be disabled. */
> +static struct gpio_desc *mlx90614_probe_wakeup(struct i2c_client *client)
> +{
> +	struct gpio_desc *gpio;
> +
> +	if (!i2c_check_functionality(client->adapter,
> +						I2C_FUNC_SMBUS_WRITE_BYTE)) {
> +		dev_info(&client->dev,
> +			 "i2c adapter does not support SMBUS_WRITE_BYTE, sleep disabled");
> +		return NULL;
> +	}
> +
> +	gpio = devm_gpiod_get_optional(&client->dev, "wakeup", GPIOD_IN);
> +
> +	if (IS_ERR(gpio)) {
> +		dev_warn(&client->dev,
> +			 "gpio acquisition failed with error %ld, sleep disabled",
> +			 PTR_ERR(gpio));
> +		return NULL;
> +	} else if (!gpio) {
> +		dev_info(&client->dev,
> +			 "wakeup-gpio not found, sleep disabled");
> +	}
> +
> +	return gpio;
> +}
> +#else
> +static inline int mlx90614_sleep(struct mlx90614_data *data)
> +{
> +	return -ENOSYS;
> +}
> +static inline int mlx90614_wakeup(struct mlx90614_data *data)
> +{
> +	return -ENOSYS;
> +}
> +static inline struct gpio_desc *mlx90614_probe_wakeup(struct i2c_client *client)
> +{
> +	return NULL;
> +}
> +#endif
> +
>  /* Return 0 for single sensor, 1 for dual sensor, <0 on error. */
>  static int mlx90614_probe_model(struct i2c_client *client)
>  {
> @@ -351,6 +513,9 @@ static int mlx90614_probe(struct i2c_client *client,
>  	i2c_set_clientdata(client, indio_dev);
>  	data->client = client;
>  	mutex_init(&data->lock);
> +	data->wakeup_gpio = mlx90614_probe_wakeup(client);
> +
> +	mlx90614_wakeup(data);
>  
>  	indio_dev->dev.parent = &client->dev;
>  	indio_dev->name = id->name;
> @@ -373,12 +538,30 @@ static int mlx90614_probe(struct i2c_client *client,
>  		return ret;
>  	}
>  
> +	if (data->wakeup_gpio) {
> +		pm_runtime_set_autosuspend_delay(&client->dev,
> +						 MLX90614_AUTOSLEEP_DELAY);
> +		pm_runtime_use_autosuspend(&client->dev);
> +		pm_runtime_set_active(&client->dev);
> +		pm_runtime_enable(&client->dev);
> +	}
> +
>  	return iio_device_register(indio_dev);
>  }
>  
>  static int mlx90614_remove(struct i2c_client *client)
>  {
> -	iio_device_unregister(i2c_get_clientdata(client));
> +	struct iio_dev *indio_dev = i2c_get_clientdata(client);
> +	struct mlx90614_data *data = iio_priv(indio_dev);
> +
> +	if (data->wakeup_gpio) {
> +		pm_runtime_disable(&client->dev);
> +		if (!pm_runtime_status_suspended(&client->dev))
> +			mlx90614_sleep(data);
> +		pm_runtime_set_suspended(&client->dev);
> +	}
> +
> +	iio_device_unregister(indio_dev);
>  
>  	return 0;
>  }
> @@ -389,10 +572,67 @@ static const struct i2c_device_id mlx90614_id[] = {
>  };
>  MODULE_DEVICE_TABLE(i2c, mlx90614_id);
>  
> +#ifdef CONFIG_PM_SLEEP
> +static int mlx90614_pm_suspend(struct device *dev)
> +{
> +	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
> +	struct mlx90614_data *data = iio_priv(indio_dev);
> +
> +	if (data->wakeup_gpio && pm_runtime_active(dev))
> +		return mlx90614_sleep(data);
> +
> +	return 0;
> +}
> +
> +static int mlx90614_pm_resume(struct device *dev)
> +{
> +	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
> +	struct mlx90614_data *data = iio_priv(indio_dev);
> +	int err;
> +
> +	if (data->wakeup_gpio) {
> +		err = mlx90614_wakeup(data);
> +		if (err < 0)
> +			return err;
> +
> +		pm_runtime_disable(dev);
> +		pm_runtime_set_active(dev);
> +		pm_runtime_enable(dev);
> +	}
> +
> +	return 0;
> +}
> +#endif
> +
> +#ifdef CONFIG_PM
> +static int mlx90614_pm_runtime_suspend(struct device *dev)
> +{
> +	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
> +	struct mlx90614_data *data = iio_priv(indio_dev);
> +
> +	return mlx90614_sleep(data);
> +}
> +
> +static int mlx90614_pm_runtime_resume(struct device *dev)
> +{
> +	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
> +	struct mlx90614_data *data = iio_priv(indio_dev);
> +
> +	return mlx90614_wakeup(data);
> +}
> +#endif
> +
> +static const struct dev_pm_ops mlx90614_pm_ops = {
> +	SET_SYSTEM_SLEEP_PM_OPS(mlx90614_pm_suspend, mlx90614_pm_resume)
> +	SET_RUNTIME_PM_OPS(mlx90614_pm_runtime_suspend,
> +			   mlx90614_pm_runtime_resume, NULL)
> +};
> +
>  static struct i2c_driver mlx90614_driver = {
>  	.driver = {
>  		.name	= "mlx90614",
>  		.owner	= THIS_MODULE,
> +		.pm	= &mlx90614_pm_ops,
>  	},
>  	.probe = mlx90614_probe,
>  	.remove = mlx90614_remove,
> 

Re: [PATCH 6/7] iio: mlx90614: Add power management

[Jonathan Cameron]

On 09/03/15 15:39, Jonathan Cameron wrote:
> On 25/02/15 15:55, Vianney le Clément de Saint-Marcq wrote:
>> Add support for system sleep and runtime power management.
>>
>> To wake up the device, the SDA line should be held low for at least 33ms
>> while SCL is high.  As this is not possible using the i2c API (and not
>> supported by all i2c adapters), a GPIO connected to the SDA line is
>> needed.  The GPIO is named "wakeup" and can be specified in a device
>> tree with the "wakeup-gpios" binding.
> Needs some i2c specialist input on this!  As you mentioned it is liable
> to be controversial.  Wolfram, is this a one off special or do
> any other devices do this sort of magic?
>>
>> If the wake-up GPIO is not given, disable power management for the
>> device.  Entering sleep requires an SMBus byte access, hence power
>> management is also disabled if byte access is not supported by the
>> adapter.
>>
>> Signed-off-by: Vianney le Clément de Saint-Marcq <vianney.leclement-buIOx9BAs4sybS5Ee8rs3A@public.gmane.org>
>> Cc: Arnout Vandecappelle (Essensium/Mind) <arnout-agwphqFHkxc@public.gmane.org>
Again, with a current address for Wolfram.
>>
>> ---
>>
>> The default autosleep delay (5s) is chosen arbitrarily, trying to take
>> into account the long startup time (250ms).  Feel free to change it to
>> another value if you think it is saner.
>> ---
>>  .../bindings/iio/temperature/mlx90614.txt          |  24 ++
>>  .../devicetree/bindings/vendor-prefixes.txt        |   1 +
>>  drivers/iio/temperature/mlx90614.c                 | 244 ++++++++++++++++++++-
>>  3 files changed, 267 insertions(+), 2 deletions(-)
>>  create mode 100644 Documentation/devicetree/bindings/iio/temperature/mlx90614.txt
>>
>> diff --git a/Documentation/devicetree/bindings/iio/temperature/mlx90614.txt b/Documentation/devicetree/bindings/iio/temperature/mlx90614.txt
>> new file mode 100644
>> index 0000000..9be57b0
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/iio/temperature/mlx90614.txt
>> @@ -0,0 +1,24 @@
>> +* Melexis MLX90614 contactless IR temperature sensor
>> +
>> +http://melexis.com/Infrared-Thermometer-Sensors/Infrared-Thermometer-Sensors/MLX90614-615.aspx
>> +
>> +Required properties:
>> +
>> +  - compatible: should be "melexis,mlx90614"
>> +  - reg: the I2C address of the sensor
>> +
>> +Optional properties:
>> +
>> +  - wakeup-gpios: device tree identifier of the GPIO connected to the SDA line
>> +      to hold low in order to wake up the device.  In normal operation, the
>> +      GPIO is set as input and will not interfere in I2C communication.  There
>> +      is no need for a GPIO driving the SCL line.  If no GPIO is given, power
>> +      management is disabled.
>> +
>> +Example:
>> +
>> +mlx90614@5a {
>> +	compatible = "melexis,mlx90614";
>> +	reg = <0x5a>;
>> +	wakeup-gpios = <&gpio0 2 GPIO_ACTIVE_HIGH>;
>> +};
>> diff --git a/Documentation/devicetree/bindings/vendor-prefixes.txt b/Documentation/devicetree/bindings/vendor-prefixes.txt
>> index 389ca13..ceacc40 100644
>> --- a/Documentation/devicetree/bindings/vendor-prefixes.txt
>> +++ b/Documentation/devicetree/bindings/vendor-prefixes.txt
>> @@ -108,6 +108,7 @@ lltc	Linear Technology Corporation
>>  marvell	Marvell Technology Group Ltd.
>>  maxim	Maxim Integrated Products
>>  mediatek	MediaTek Inc.
>> +melexis	Melexis N.V.
>>  merrii	Merrii Technology Co., Ltd.
>>  micrel	Micrel Inc.
>>  microchip	Microchip Technology Inc.
>> diff --git a/drivers/iio/temperature/mlx90614.c b/drivers/iio/temperature/mlx90614.c
>> index ab98fb6..49c517a 100644
>> --- a/drivers/iio/temperature/mlx90614.c
>> +++ b/drivers/iio/temperature/mlx90614.c
>> @@ -12,13 +12,22 @@
>>   *
>>   * (7-bit I2C slave address 0x5a, 100KHz bus speed only!)
>>   *
>> - * TODO: sleep mode
>> + * To wake up from sleep mode, the SDA line must be held low while SCL is high
>> + * for at least 33ms.  This is achieved with an extra GPIO that can be connected
>> + * directly to the SDA line.  In normal operation, the GPIO is set as input and
>> + * will not interfere in I2C communication.  While the GPIO is driven low, the
>> + * i2c adapter is locked since it cannot be used by other clients.  The SCL line
>> + * always has a pull-up so we do not need an extra GPIO to drive it high.  If
>> + * the "wakeup" GPIO is not given, power management will be disabled.
>>   */
>>  
>>  #include <linux/err.h>
>>  #include <linux/i2c.h>
>>  #include <linux/module.h>
>>  #include <linux/delay.h>
>> +#include <linux/jiffies.h>
>> +#include <linux/gpio/consumer.h>
>> +#include <linux/pm_runtime.h>
>>  
>>  #include <linux/iio/iio.h>
>>  #include <linux/iio/sysfs.h>
>> @@ -53,9 +62,13 @@
>>  #define MLX90614_TIMING_WAKEUP 34 /* time to hold SDA low for wake-up */
>>  #define MLX90614_TIMING_STARTUP 250 /* time before first data after wake-up */
>>  
>> +#define MLX90614_AUTOSLEEP_DELAY 5000 /* default autosleep delay */
>> +
>>  struct mlx90614_data {
>>  	struct i2c_client *client;
>>  	struct mutex lock; /* for EEPROM access only */
>> +	struct gpio_desc *wakeup_gpio; /* NULL to disable sleep/wake-up */
>> +	unsigned long ready_timestamp; /* in jiffies */
>>  };
>>  
>>  /*
>> @@ -96,6 +109,52 @@ static s32 mlx90614_write_word(const struct i2c_client *client, u8 command,
>>  	return ret;
>>  }
>>  
>> +#ifdef CONFIG_PM
>> +/*
>> + * If @startup is true, make sure MLX90614_TIMING_STARTUP ms have elapsed since
>> + * the last wake-up.  This is normally only needed to get a valid temperature
>> + * reading.  EEPROM access does not need such delay.
>> + */
>> +static void mlx90614_power_get(struct mlx90614_data *data, bool startup)
>> +{
>> +	unsigned long now;
>> +
>> +	if (!data->wakeup_gpio)
>> +		return;
>> +
>> +	pm_runtime_get_sync(&data->client->dev);
>> +
>> +	if (startup) {
>> +		/*
>> +		 * If the process requesting the temperature gets killed when
>> +		 * waiting here, it does not matter whether the reading is
>> +		 * valid.  Hence, the sleep is interruptible.
>> +		 */
>> +		now = jiffies;
>> +		if (time_before(now, data->ready_timestamp))
>> +			msleep_interruptible(jiffies_to_msecs(
>> +						data->ready_timestamp - now));
>> +	}
>> +}
>> +
>> +static void mlx90614_power_put(struct mlx90614_data *data)
>> +{
>> +	if (!data->wakeup_gpio)
>> +		return;
>> +
>> +	pm_runtime_mark_last_busy(&data->client->dev);
>> +	pm_runtime_put_autosuspend(&data->client->dev);
>> +}
>> +#else
>> +static inline void mlx90614_power_get(struct mlx90614_data *data, bool startup)
>> +{
>> +}
>> +
>> +static inline void mlx90614_power_put(struct mlx90614_data *data)
>> +{
>> +}
>> +#endif
>> +
>>  static int mlx90614_read_raw(struct iio_dev *indio_dev,
>>  			    struct iio_chan_spec const *channel, int *val,
>>  			    int *val2, long mask)
>> @@ -127,7 +186,10 @@ static int mlx90614_read_raw(struct iio_dev *indio_dev,
>>  			return -EINVAL;
>>  		}
>>  
>> +		mlx90614_power_get(data, true);
>>  		ret = i2c_smbus_read_word_data(data->client, cmd);
>> +		mlx90614_power_put(data);
>> +
>>  		if (ret < 0)
>>  			return ret;
>>  
>> @@ -160,9 +222,11 @@ static ssize_t mlx90614_show_emissivity(struct device *dev,
>>  	struct mlx90614_data *data = iio_priv(indio_dev);
>>  	s32 ret;
>>  
>> +	mlx90614_power_get(data, false);
>>  	mutex_lock(&data->lock);
>>  	ret = i2c_smbus_read_word_data(data->client, MLX90614_EMISSIVITY);
>>  	mutex_unlock(&data->lock);
>> +	mlx90614_power_put(data);
>>  
>>  	if (ret < 0)
>>  		return ret;
>> @@ -182,9 +246,11 @@ static ssize_t mlx90614_store_emissivity(struct device *dev,
>>  	if (kstrtou16(buf, 0, &val))
>>  		return -EINVAL;
>>  
>> +	mlx90614_power_get(data, false);
>>  	mutex_lock(&data->lock);
>>  	ret = mlx90614_write_word(data->client, MLX90614_EMISSIVITY, val);
>>  	mutex_unlock(&data->lock);
>> +	mlx90614_power_put(data);
>>  
>>  	if (ret < 0)
>>  		return ret;
>> @@ -203,9 +269,11 @@ static ssize_t mlx90614_show_config(struct device *dev,
>>  	u16 shift = indio_attr->address >> 16;
>>  	s32 ret;
>>  
>> +	mlx90614_power_get(data, false);
>>  	mutex_lock(&data->lock);
>>  	ret = i2c_smbus_read_word_data(data->client, MLX90614_CONFIG);
>>  	mutex_unlock(&data->lock);
>> +	mlx90614_power_put(data);
>>  
>>  	if (ret < 0)
>>  		return ret;
>> @@ -230,6 +298,7 @@ static ssize_t mlx90614_store_config(struct device *dev,
>>  	if (kstrtou16(buf, 0, &val) || val != (val & (mask >> shift)))
>>  		return -EINVAL;
>>  
>> +	mlx90614_power_get(data, false);
>>  	mutex_lock(&data->lock);
>>  
>>  	ret = i2c_smbus_read_word_data(data->client, MLX90614_CONFIG);
>> @@ -241,6 +310,7 @@ static ssize_t mlx90614_store_config(struct device *dev,
>>  
>>  out:
>>  	mutex_unlock(&data->lock);
>> +	mlx90614_power_put(data);
>>  
>>  	if (ret < 0)
>>  		return ret;
>> @@ -320,6 +390,98 @@ static const struct iio_info mlx90614_info = {
>>  	.driver_module = THIS_MODULE,
>>  };
>>  
>> +#ifdef CONFIG_PM
>> +static int mlx90614_sleep(struct mlx90614_data *data)
>> +{
>> +	s32 ret;
>> +
>> +	if (!data->wakeup_gpio) {
>> +		dev_dbg(&data->client->dev, "Sleep disabled");
>> +		return -ENOSYS;
>> +	}
>> +
>> +	dev_dbg(&data->client->dev, "Requesting sleep");
>> +
>> +	mutex_lock(&data->lock);
>> +	ret = i2c_smbus_xfer(data->client->adapter, data->client->addr,
>> +			     data->client->flags | I2C_CLIENT_PEC,
>> +			     I2C_SMBUS_WRITE, MLX90614_OP_SLEEP,
>> +			     I2C_SMBUS_BYTE, NULL);
>> +	mutex_unlock(&data->lock);
>> +
>> +	return ret;
>> +}
>> +
>> +static int mlx90614_wakeup(struct mlx90614_data *data)
>> +{
>> +	if (!data->wakeup_gpio) {
>> +		dev_dbg(&data->client->dev, "Wake-up disabled");
>> +		return -ENOSYS;
>> +	}
>> +
>> +	dev_dbg(&data->client->dev, "Requesting wake-up");
>> +
>> +	i2c_lock_adapter(data->client->adapter);
>> +	gpiod_direction_output(data->wakeup_gpio, 0);
>> +	msleep(MLX90614_TIMING_WAKEUP);
>> +	gpiod_direction_input(data->wakeup_gpio);
>> +	i2c_unlock_adapter(data->client->adapter);
>> +
>> +	data->ready_timestamp = jiffies +
>> +			msecs_to_jiffies(MLX90614_TIMING_STARTUP);
>> +
>> +	/*
>> +	 * Quirk: the i2c controller may get confused right after the
>> +	 * wake-up signal has been sent.  As a workaround, do a dummy read.
>> +	 * If the read fails, the controller will probably be reset so that
>> +	 * further reads will work.
>> +	 */
>> +	i2c_smbus_read_word_data(data->client, MLX90614_CONFIG);
>> +
>> +	return 0;
>> +}
>> +
>> +/* Return wake-up GPIO or NULL if sleep functionality should be disabled. */
>> +static struct gpio_desc *mlx90614_probe_wakeup(struct i2c_client *client)
>> +{
>> +	struct gpio_desc *gpio;
>> +
>> +	if (!i2c_check_functionality(client->adapter,
>> +						I2C_FUNC_SMBUS_WRITE_BYTE)) {
>> +		dev_info(&client->dev,
>> +			 "i2c adapter does not support SMBUS_WRITE_BYTE, sleep disabled");
>> +		return NULL;
>> +	}
>> +
>> +	gpio = devm_gpiod_get_optional(&client->dev, "wakeup", GPIOD_IN);
>> +
>> +	if (IS_ERR(gpio)) {
>> +		dev_warn(&client->dev,
>> +			 "gpio acquisition failed with error %ld, sleep disabled",
>> +			 PTR_ERR(gpio));
>> +		return NULL;
>> +	} else if (!gpio) {
>> +		dev_info(&client->dev,
>> +			 "wakeup-gpio not found, sleep disabled");
>> +	}
>> +
>> +	return gpio;
>> +}
>> +#else
>> +static inline int mlx90614_sleep(struct mlx90614_data *data)
>> +{
>> +	return -ENOSYS;
>> +}
>> +static inline int mlx90614_wakeup(struct mlx90614_data *data)
>> +{
>> +	return -ENOSYS;
>> +}
>> +static inline struct gpio_desc *mlx90614_probe_wakeup(struct i2c_client *client)
>> +{
>> +	return NULL;
>> +}
>> +#endif
>> +
>>  /* Return 0 for single sensor, 1 for dual sensor, <0 on error. */
>>  static int mlx90614_probe_model(struct i2c_client *client)
>>  {
>> @@ -351,6 +513,9 @@ static int mlx90614_probe(struct i2c_client *client,
>>  	i2c_set_clientdata(client, indio_dev);
>>  	data->client = client;
>>  	mutex_init(&data->lock);
>> +	data->wakeup_gpio = mlx90614_probe_wakeup(client);
>> +
>> +	mlx90614_wakeup(data);
>>  
>>  	indio_dev->dev.parent = &client->dev;
>>  	indio_dev->name = id->name;
>> @@ -373,12 +538,30 @@ static int mlx90614_probe(struct i2c_client *client,
>>  		return ret;
>>  	}
>>  
>> +	if (data->wakeup_gpio) {
>> +		pm_runtime_set_autosuspend_delay(&client->dev,
>> +						 MLX90614_AUTOSLEEP_DELAY);
>> +		pm_runtime_use_autosuspend(&client->dev);
>> +		pm_runtime_set_active(&client->dev);
>> +		pm_runtime_enable(&client->dev);
>> +	}
>> +
>>  	return iio_device_register(indio_dev);
>>  }
>>  
>>  static int mlx90614_remove(struct i2c_client *client)
>>  {
>> -	iio_device_unregister(i2c_get_clientdata(client));
>> +	struct iio_dev *indio_dev = i2c_get_clientdata(client);
>> +	struct mlx90614_data *data = iio_priv(indio_dev);
>> +
>> +	if (data->wakeup_gpio) {
>> +		pm_runtime_disable(&client->dev);
>> +		if (!pm_runtime_status_suspended(&client->dev))
>> +			mlx90614_sleep(data);
>> +		pm_runtime_set_suspended(&client->dev);
>> +	}
>> +
>> +	iio_device_unregister(indio_dev);
>>  
>>  	return 0;
>>  }
>> @@ -389,10 +572,67 @@ static const struct i2c_device_id mlx90614_id[] = {
>>  };
>>  MODULE_DEVICE_TABLE(i2c, mlx90614_id);
>>  
>> +#ifdef CONFIG_PM_SLEEP
>> +static int mlx90614_pm_suspend(struct device *dev)
>> +{
>> +	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
>> +	struct mlx90614_data *data = iio_priv(indio_dev);
>> +
>> +	if (data->wakeup_gpio && pm_runtime_active(dev))
>> +		return mlx90614_sleep(data);
>> +
>> +	return 0;
>> +}
>> +
>> +static int mlx90614_pm_resume(struct device *dev)
>> +{
>> +	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
>> +	struct mlx90614_data *data = iio_priv(indio_dev);
>> +	int err;
>> +
>> +	if (data->wakeup_gpio) {
>> +		err = mlx90614_wakeup(data);
>> +		if (err < 0)
>> +			return err;
>> +
>> +		pm_runtime_disable(dev);
>> +		pm_runtime_set_active(dev);
>> +		pm_runtime_enable(dev);
>> +	}
>> +
>> +	return 0;
>> +}
>> +#endif
>> +
>> +#ifdef CONFIG_PM
>> +static int mlx90614_pm_runtime_suspend(struct device *dev)
>> +{
>> +	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
>> +	struct mlx90614_data *data = iio_priv(indio_dev);
>> +
>> +	return mlx90614_sleep(data);
>> +}
>> +
>> +static int mlx90614_pm_runtime_resume(struct device *dev)
>> +{
>> +	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
>> +	struct mlx90614_data *data = iio_priv(indio_dev);
>> +
>> +	return mlx90614_wakeup(data);
>> +}
>> +#endif
>> +
>> +static const struct dev_pm_ops mlx90614_pm_ops = {
>> +	SET_SYSTEM_SLEEP_PM_OPS(mlx90614_pm_suspend, mlx90614_pm_resume)
>> +	SET_RUNTIME_PM_OPS(mlx90614_pm_runtime_suspend,
>> +			   mlx90614_pm_runtime_resume, NULL)
>> +};
>> +
>>  static struct i2c_driver mlx90614_driver = {
>>  	.driver = {
>>  		.name	= "mlx90614",
>>  		.owner	= THIS_MODULE,
>> +		.pm	= &mlx90614_pm_ops,
>>  	},
>>  	.probe = mlx90614_probe,
>>  	.remove = mlx90614_remove,
>>
> 

Re: [PATCH 6/7] iio: mlx90614: Add power management

[Wolfram Sang]

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On Mon, Mar 09, 2015 at 03:39:35PM +0000, Jonathan Cameron wrote:
> On 25/02/15 15:55, Vianney le Clément de Saint-Marcq wrote:
> > Add support for system sleep and runtime power management.
> > 
> > To wake up the device, the SDA line should be held low for at least 33ms
> > while SCL is high.  As this is not possible using the i2c API (and not
> > supported by all i2c adapters), a GPIO connected to the SDA line is
> > needed.  The GPIO is named "wakeup" and can be specified in a device
> > tree with the "wakeup-gpios" binding.
> Needs some i2c specialist input on this!  As you mentioned it is liable
> to be controversial.  Wolfram, is this a one off special or do
> any other devices do this sort of magic?

s/magic/insanity/ :)

I have never heard of something like this. Unsuprisingly, I can
not recommend doing it this way. But we all know hardware...

And while we could think about reusing the bus_recovery_infrastructure,
I don't think it is worth the hazzle. So, doing this GPIO fallback may
well be the best we can do now.


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Re: [PATCH 6/7] iio: mlx90614: Add power management

[Jonathan Cameron]

On 09/03/15 16:43, Wolfram Sang wrote:
> On Mon, Mar 09, 2015 at 03:39:35PM +0000, Jonathan Cameron wrote:
>> On 25/02/15 15:55, Vianney le Clément de Saint-Marcq wrote:
>>> Add support for system sleep and runtime power management.
>>>
>>> To wake up the device, the SDA line should be held low for at least 33ms
>>> while SCL is high.  As this is not possible using the i2c API (and not
>>> supported by all i2c adapters), a GPIO connected to the SDA line is
>>> needed.  The GPIO is named "wakeup" and can be specified in a device
>>> tree with the "wakeup-gpios" binding.
>> Needs some i2c specialist input on this!  As you mentioned it is liable
>> to be controversial.  Wolfram, is this a one off special or do
>> any other devices do this sort of magic?
> 
> s/magic/insanity/ :)
> 
> I have never heard of something like this. Unsuprisingly, I can
> not recommend doing it this way. But we all know hardware...
> 
> And while we could think about reusing the bus_recovery_infrastructure,
> I don't think it is worth the hazzle. So, doing this GPIO fallback may
> well be the best we can do now.
> 
Fair enough.  Lets go with this approach then and hope this is the only bit
of hardware ever to do this (yeah right ;)