iio: gyro: itg3200: add suspend/resume support.

Unless we put the device to sleep when not it use, it wastes
6mA.

If the device is asleep on probe, the 'id' register
sometimes mis-reads - so reset first.  If the device responds
at all a command sent to the address, it is almost certainly
the correct device already.

Acked-by: Manuel Stahl <manuel.stahl@iis.fraunhofer.de>
Acked-by: Hartmut Knaack <knaack.h@gmx.de>
Signed-off-by: NeilBrown <neil@brown.name>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

diff --git a/drivers/iio/gyro/itg3200_core.c b/drivers/iio/gyro/itg3200_core.c
index 6a8020d4814038b67cbad3b3c51d20d1987bbd77..f0fd94055d8858b722a5572b564edf0de125a90b 100644 (file)
--- a/drivers/iio/gyro/itg3200_core.c
+++ b/drivers/iio/gyro/itg3200_core.c
@@ -223,6 +223,10 @@ static int itg3200_initial_setup(struct iio_dev *indio_dev)
        int ret;
        u8 val;
 
+       ret = itg3200_reset(indio_dev);
+       if (ret)
+               goto err_ret;
+
        ret = itg3200_read_reg_8(indio_dev, ITG3200_REG_ADDRESS, &val);
        if (ret)
                goto err_ret;
@@ -233,10 +237,6 @@ static int itg3200_initial_setup(struct iio_dev *indio_dev)
                goto err_ret;
        }
 
-       ret = itg3200_reset(indio_dev);
-       if (ret)
-               goto err_ret;
-
        ret = itg3200_enable_full_scale(indio_dev);
 err_ret:
        return ret;
@@ -351,6 +351,26 @@ static int itg3200_remove(struct i2c_client *client)
        return 0;
 }
 
+static int __maybe_unused itg3200_suspend(struct device *dev)
+{
+       struct iio_dev *indio_dev = dev_get_drvdata(dev);
+       struct itg3200 *st = iio_priv(indio_dev);
+
+       dev_dbg(&st->i2c->dev, "suspend device");
+
+       return itg3200_write_reg_8(indio_dev, ITG3200_REG_POWER_MANAGEMENT,
+                                  ITG3200_SLEEP);
+}
+
+static int __maybe_unused itg3200_resume(struct device *dev)
+{
+       struct iio_dev *indio_dev = dev_get_drvdata(dev);
+
+       return itg3200_initial_setup(indio_dev);
+}
+
+static SIMPLE_DEV_PM_OPS(itg3200_pm_ops, itg3200_suspend, itg3200_resume);
+
 static const struct i2c_device_id itg3200_id[] = {
        { "itg3200", 0 },
        { }
@@ -361,6 +381,7 @@ static struct i2c_driver itg3200_driver = {
        .driver = {
                .owner  = THIS_MODULE,
                .name   = "itg3200",
+               .pm     = &itg3200_pm_ops,
        },
        .id_table       = itg3200_id,
        .probe          = itg3200_probe,