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@xxxxxxxxxxxxx> >> Cc: Arnout Vandecappelle (Essensium/Mind) <arnout@xxxxxxx> 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, >> > -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
