[RFC PATCH 1/3] iio: imu: st_lsm6dsx: add wake on accelerometer threshold

Sean Nyekjaer
2019-06-14T12:26:22Z

Added wakeup-source option for waking on accelerometer events.
If the wakeup-source is specified, we activate this on our
way down to suspend. We start the accelerometer in
low power mode and wait for it to report a wake event.

Signed-off-by: Sean Nyekjaer <sean@geanix.com>
---
drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h | 2 +
drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c | 70 ++++++++++++++++++++
2 files changed, 72 insertions(+)

diff --git a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h
index edcd838037cd..ef4327fd57d6 100644
--- a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h
+++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h
@@ -147,6 +147,7 @@ struct st_lsm6dsx_hw {
struct device *dev;
struct regmap *regmap;
int irq;
+ bool irq_wake;

struct mutex fifo_lock;
struct mutex conf_lock;
@@ -155,6 +156,7 @@ struct st_lsm6dsx_hw {
u8 enable_mask;
u8 ts_sip;
u8 sip;
+ u8 wake_threshold;

u8 *buff;

diff --git a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c
index aebbe0ddd8d8..092c4d02bd4e 100644
--- a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c
+++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c
@@ -36,6 +36,7 @@
#include <linux/delay.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
+#include <linux/interrupt.h>
#include <linux/pm.h>
#include <linux/regmap.h>
#include <linux/bitfield.h>
@@ -71,6 +72,17 @@
#define ST_LSM6DSX_REG_GYRO_OUT_Y_L_ADDR 0x24
#define ST_LSM6DSX_REG_GYRO_OUT_Z_L_ADDR 0x26

+#define ST_LSM6DSX_REG_TAP_CFG_ADDR 0x58
+#define ST_LSM6DSX_REG_TAP_CFG_INT_EN_MASK BIT(7)
+#define ST_LSM6DSX_REG_TAP_CFG_INACT_EN_MASK GENMASK(6, 5)
+
+#define ST_LSM6DSX_DEFAULT_WAKE_THRESH 0
+#define ST_LSM6DSX_REG_WAKE_UP_THS_ADDR 0x5B
+#define ST_LSM6DSX_REG_WAKE_UP_THS_THRES_MASK GENMASK(5, 0)
+
+#define ST_LSM6DSX_REG_MD1_CFG_ADDR 0x5E
+#define ST_LSM6DSX_REG_MD1_CFG_INT1_WU_MASK BIT(5)
+
#define ST_LSM6DSX_ACC_FS_2G_GAIN IIO_G_TO_M_S_2(61)
#define ST_LSM6DSX_ACC_FS_4G_GAIN IIO_G_TO_M_S_2(122)
#define ST_LSM6DSX_ACC_FS_8G_GAIN IIO_G_TO_M_S_2(244)
@@ -428,6 +440,19 @@ static int st_lsm6dsx_set_odr(struct st_lsm6dsx_sensor *sensor, u16 odr)
ST_LSM6DSX_SHIFT_VAL(val, reg->mask));
}

+static int st_lsm6dsx_set_wake_threshold(struct st_lsm6dsx_hw *hw, u8 threshold)
+{
+ int err = 0;
+
+ err = regmap_update_bits(hw->regmap, ST_LSM6DSX_REG_WAKE_UP_THS_ADDR,
+ ST_LSM6DSX_REG_WAKE_UP_THS_THRES_MASK,
+ threshold);
+ if (!err)
+ hw->wake_threshold = threshold;
+
+ return err;
+}
+
int st_lsm6dsx_sensor_enable(struct st_lsm6dsx_sensor *sensor)
{
int err;
@@ -754,6 +779,8 @@ static int st_lsm6dsx_init_device(struct st_lsm6dsx_hw *hw)
if (err < 0)
return err;

+ st_lsm6dsx_set_wake_threshold(hw, ST_LSM6DSX_DEFAULT_WAKE_THRESH);
+
return st_lsm6dsx_init_hw_timer(hw);
}

@@ -853,6 +880,10 @@ int st_lsm6dsx_probe(struct device *dev, int irq, int hw_id, const char *name,
return err;
}

+ if (dev->of_node)
+ if (of_property_read_bool(dev->of_node, "wakeup-source"))
+ device_init_wakeup(dev, true);
+
return 0;
}
EXPORT_SYMBOL(st_lsm6dsx_probe);
@@ -879,6 +910,26 @@ static int __maybe_unused st_lsm6dsx_suspend(struct device *dev)
if (hw->fifo_mode != ST_LSM6DSX_FIFO_BYPASS)
err = st_lsm6dsx_flush_fifo(hw);

+ if (device_may_wakeup(dev)) {
+ sensor = iio_priv(hw->iio_devs[ST_LSM6DSX_ID_ACC]);
+ err = st_lsm6dsx_sensor_enable(sensor);
+
+ /* Enable inactivity function - low power ACC, GYRO powered-down */
+ err = regmap_update_bits(hw->regmap, ST_LSM6DSX_REG_TAP_CFG_ADDR,
+ ST_LSM6DSX_REG_TAP_CFG_INT_EN_MASK |
+ ST_LSM6DSX_REG_TAP_CFG_INACT_EN_MASK,
+ ST_LSM6DSX_REG_TAP_CFG_INT_EN_MASK |
+ ST_LSM6DSX_REG_TAP_CFG_INACT_EN_MASK);
+
+ /* Enable wakeup interrupt */
+ err = regmap_update_bits(hw->regmap, ST_LSM6DSX_REG_MD1_CFG_ADDR,
+ ST_LSM6DSX_REG_MD1_CFG_INT1_WU_MASK,
+ ST_LSM6DSX_REG_MD1_CFG_INT1_WU_MASK);
+
+ /* Enable wake from IRQ */
+ hw->irq_wake = (enable_irq_wake(hw->irq) == 0);
+ }
+
return err;
}

@@ -888,6 +939,25 @@ static int __maybe_unused st_lsm6dsx_resume(struct device *dev)
struct st_lsm6dsx_sensor *sensor;
int i, err = 0;

+ if (device_may_wakeup(dev) && hw->irq_wake) {
+ disable_irq_wake(hw->irq);
+ hw->irq_wake = false;
+
+ sensor = iio_priv(hw->iio_devs[ST_LSM6DSX_ID_ACC]);
+ err = st_lsm6dsx_sensor_disable(sensor);
+
+ /* Disable inactivity function */
+ err = regmap_update_bits(hw->regmap, ST_LSM6DSX_REG_TAP_CFG_ADDR,
+ ST_LSM6DSX_REG_TAP_CFG_INT_EN_MASK |
+ ST_LSM6DSX_REG_TAP_CFG_INACT_EN_MASK,
+ 0);
+
+ /* Disable wakeup interrupt */
+ err = regmap_update_bits(hw->regmap, ST_LSM6DSX_REG_MD1_CFG_ADDR,
+ ST_LSM6DSX_REG_MD1_CFG_INT1_WU_MASK,
+ 0);
+ }
+
for (i = 0; i < ST_LSM6DSX_ID_MAX; i++) {
sensor = iio_priv(hw->iio_devs[i]);
if (!(hw->enable_mask & BIT(sensor->id)))
--
2.22.0