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@xxxxxxxxxxxxx> > Cc: Arnout Vandecappelle (Essensium/Mind) <arnout@xxxxxxx> > > --- > > 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, > -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
