From 0c3a333524a3e5ba4b6c7b2638faef8420cfdb2a Mon Sep 17 00:00:00 2001 From: Rajat Khandelwal Date: Mon, 10 Oct 2022 23:07:20 +0530 Subject: [PATCH] iio: pressure: mpl115: Implementing low power mode by shutdown gpio MPL115 supports shutdown gpio which can be used to set the state to low power mode. Power from all internal circuits and registers is removed. This is done by pulling the SHDN pin to low. This patch enables runtime PM on MPL115 to increase power savings. According to spec., a wakeup time period of ~5 ms exists between waking up and actually communicating with the device. This is implemented using sleep delay. Signed-off-by: Rajat Khandelwal Link: https://lore.kernel.org/r/20221010173720.568916-1-rajat.khandelwal@linux.intel.com Signed-off-by: Jonathan Cameron --- drivers/iio/pressure/mpl115.c | 62 ++++++++++++++++++++++++++++++- drivers/iio/pressure/mpl115.h | 5 +++ drivers/iio/pressure/mpl115_i2c.c | 1 + drivers/iio/pressure/mpl115_spi.c | 1 + 4 files changed, 68 insertions(+), 1 deletion(-) diff --git a/drivers/iio/pressure/mpl115.c b/drivers/iio/pressure/mpl115.c index 5bf5b9abe6f1a..02ea38c8a3e43 100644 --- a/drivers/iio/pressure/mpl115.c +++ b/drivers/iio/pressure/mpl115.c @@ -4,12 +4,13 @@ * * Copyright (c) 2014 Peter Meerwald * - * TODO: shutdown pin + * TODO: synchronization with system suspend */ #include #include #include +#include #include "mpl115.h" @@ -27,6 +28,7 @@ struct mpl115_data { s16 a0; s16 b1, b2; s16 c12; + struct gpio_desc *shutdown; const struct mpl115_ops *ops; }; @@ -102,16 +104,24 @@ static int mpl115_read_raw(struct iio_dev *indio_dev, switch (mask) { case IIO_CHAN_INFO_PROCESSED: + pm_runtime_get_sync(data->dev); ret = mpl115_comp_pressure(data, val, val2); if (ret < 0) return ret; + pm_runtime_mark_last_busy(data->dev); + pm_runtime_put_autosuspend(data->dev); + return IIO_VAL_INT_PLUS_MICRO; case IIO_CHAN_INFO_RAW: + pm_runtime_get_sync(data->dev); /* temperature -5.35 C / LSB, 472 LSB is 25 C */ ret = mpl115_read_temp(data); if (ret < 0) return ret; + pm_runtime_mark_last_busy(data->dev); + pm_runtime_put_autosuspend(data->dev); *val = ret >> 6; + return IIO_VAL_INT; case IIO_CHAN_INFO_OFFSET: *val = -605; @@ -168,6 +178,8 @@ int mpl115_probe(struct device *dev, const char *name, if (ret) return ret; + dev_set_drvdata(dev, indio_dev); + ret = data->ops->read(data->dev, MPL115_A0); if (ret < 0) return ret; @@ -185,10 +197,58 @@ int mpl115_probe(struct device *dev, const char *name, return ret; data->c12 = ret; + data->shutdown = devm_gpiod_get_optional(dev, "shutdown", + GPIOD_OUT_LOW); + if (IS_ERR(data->shutdown)) + return dev_err_probe(dev, PTR_ERR(data->shutdown), + "cannot get shutdown gpio\n"); + + if (data->shutdown) { + /* Enable runtime PM */ + pm_runtime_get_noresume(dev); + pm_runtime_set_active(dev); + pm_runtime_enable(dev); + + /* + * As the device takes 3 ms to come up with a fresh + * reading after power-on and 5 ms to actually power-on, + * do not shut it down unnecessarily. Set autosuspend to + * 2000 ms. + */ + pm_runtime_set_autosuspend_delay(dev, 2000); + pm_runtime_use_autosuspend(dev); + pm_runtime_put(dev); + + dev_dbg(dev, "low-power mode enabled"); + } else + dev_dbg(dev, "low-power mode disabled"); + return devm_iio_device_register(dev, indio_dev); } EXPORT_SYMBOL_NS_GPL(mpl115_probe, IIO_MPL115); +static int mpl115_runtime_suspend(struct device *dev) +{ + struct mpl115_data *data = iio_priv(dev_get_drvdata(dev)); + + gpiod_set_value(data->shutdown, 1); + + return 0; +} + +static int mpl115_runtime_resume(struct device *dev) +{ + struct mpl115_data *data = iio_priv(dev_get_drvdata(dev)); + + gpiod_set_value(data->shutdown, 0); + usleep_range(5000, 6000); + + return 0; +} + +EXPORT_NS_RUNTIME_DEV_PM_OPS(mpl115_dev_pm_ops, mpl115_runtime_suspend, + mpl115_runtime_resume, NULL, IIO_MPL115); + MODULE_AUTHOR("Peter Meerwald "); MODULE_DESCRIPTION("Freescale MPL115 pressure/temperature driver"); MODULE_LICENSE("GPL"); diff --git a/drivers/iio/pressure/mpl115.h b/drivers/iio/pressure/mpl115.h index 57d55eb8e6617..78a0068a17bbc 100644 --- a/drivers/iio/pressure/mpl115.h +++ b/drivers/iio/pressure/mpl115.h @@ -6,6 +6,8 @@ * Copyright (c) 2016 Akinobu Mita */ +#include + #ifndef _MPL115_H_ #define _MPL115_H_ @@ -18,4 +20,7 @@ struct mpl115_ops { int mpl115_probe(struct device *dev, const char *name, const struct mpl115_ops *ops); +/*PM ops */ +extern const struct dev_pm_ops mpl115_dev_pm_ops; + #endif diff --git a/drivers/iio/pressure/mpl115_i2c.c b/drivers/iio/pressure/mpl115_i2c.c index 099ab1c6832c5..555bda1146fb9 100644 --- a/drivers/iio/pressure/mpl115_i2c.c +++ b/drivers/iio/pressure/mpl115_i2c.c @@ -53,6 +53,7 @@ MODULE_DEVICE_TABLE(i2c, mpl115_i2c_id); static struct i2c_driver mpl115_i2c_driver = { .driver = { .name = "mpl115", + .pm = pm_ptr(&mpl115_dev_pm_ops), }, .probe = mpl115_i2c_probe, .id_table = mpl115_i2c_id, diff --git a/drivers/iio/pressure/mpl115_spi.c b/drivers/iio/pressure/mpl115_spi.c index 7feec87e2704e..58d218fd90dcb 100644 --- a/drivers/iio/pressure/mpl115_spi.c +++ b/drivers/iio/pressure/mpl115_spi.c @@ -92,6 +92,7 @@ MODULE_DEVICE_TABLE(spi, mpl115_spi_ids); static struct spi_driver mpl115_spi_driver = { .driver = { .name = "mpl115", + .pm = pm_ptr(&mpl115_dev_pm_ops), }, .probe = mpl115_spi_probe, .id_table = mpl115_spi_ids, -- 2.30.2