On 30/03/15 09:35, 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.
>
> 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
> <[email protected]>
> Cc: Arnout Vandecappelle (Essensium/Mind) <[email protected]>
whilst this is a hideous trick, the software support here is fine!
Applied to the togreg branch of iio.git.
Jonathan
>
> ---
>
> 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.
>
> I did not roll the bodies of _pm_runtime_{suspend,resume} into
> one-liners as they would exceed 80 columns, requiring an (IMO ugly) line
> break. Besides, the first two lines are coherent with other functions,
> which arguably makes the code easier to read. No problem changing it
> though if you disagree.
>
> v3: * split out basic devicetree documentation in new patch
> * make remove the reverse of probe
> v2: return -EINTR when the startup delay is interrupted
> ---
> .../bindings/iio/temperature/mlx90614.txt | 9 +
> drivers/iio/temperature/mlx90614.c | 246
> ++++++++++++++++++++-
> 2 files changed, 253 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/iio/temperature/mlx90614.txt
> b/Documentation/devicetree/bindings/iio/temperature/mlx90614.txt
> index 4c959f3..9be57b0 100644
> --- a/Documentation/devicetree/bindings/iio/temperature/mlx90614.txt
> +++ b/Documentation/devicetree/bindings/iio/temperature/mlx90614.txt
> @@ -7,9 +7,18 @@ 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/drivers/iio/temperature/mlx90614.c
> b/drivers/iio/temperature/mlx90614.c
> index a307d8c..73ec767 100644
> --- a/drivers/iio/temperature/mlx90614.c
> +++ b/drivers/iio/temperature/mlx90614.c
> @@ -12,13 +12,24 @@
> *
> * (7-bit I2C slave address 0x5a, 100KHz bus speed only!)
> *
> - * TODO: sleep mode, filter configuration
> + * 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.
> + *
> + * TODO: filter configuration
> */
>
> #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>
>
> @@ -52,9 +63,13 @@
> #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 */
> };
>
> /*
> @@ -95,6 +110,54 @@ 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.
> + * Return 0 on success, <0 on error.
> + */
> +static int mlx90614_power_get(struct mlx90614_data *data, bool startup)
> +{
> + unsigned long now;
> +
> + if (!data->wakeup_gpio)
> + return 0;
> +
> + pm_runtime_get_sync(&data->client->dev);
> +
> + if (startup) {
> + now = jiffies;
> + if (time_before(now, data->ready_timestamp) &&
> + msleep_interruptible(jiffies_to_msecs(
> + data->ready_timestamp - now)) != 0) {
> + pm_runtime_put_autosuspend(&data->client->dev);
> + return -EINTR;
> + }
> + }
> +
> + return 0;
> +}
> +
> +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 int mlx90614_power_get(struct mlx90614_data *data, bool
> startup)
> +{
> + return 0;
> +}
> +
> +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)
> @@ -125,7 +188,12 @@ static int mlx90614_read_raw(struct iio_dev *indio_dev,
> return -EINVAL;
> }
>
> + ret = mlx90614_power_get(data, true);
> + if (ret < 0)
> + return ret;
> ret = i2c_smbus_read_word_data(data->client, cmd);
> + mlx90614_power_put(data);
> +
> if (ret < 0)
> return ret;
> *val = ret;
> @@ -138,10 +206,12 @@ static int mlx90614_read_raw(struct iio_dev *indio_dev,
> *val = 20;
> return IIO_VAL_INT;
> case IIO_CHAN_INFO_CALIBEMISSIVITY: /* 1/65535 / LSB */
> + 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;
> @@ -172,10 +242,12 @@ static int mlx90614_write_raw(struct iio_dev *indio_dev,
> return -EINVAL;
> val = val * 65535 + val2 / 15259; /* 1/65535 ~ 0.000015259 */
>
> + 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;
> @@ -235,6 +307,98 @@ 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_num_ir_sensors(struct i2c_client *client)
> {
> @@ -266,6 +430,9 @@ 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;
> @@ -288,12 +455,30 @@ 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);
> +
> + iio_device_unregister(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);
> + }
>
> return 0;
> }
> @@ -304,10 +489,67 @@ 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,
>
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