iio: accel: kxsd9: Deploy system and runtime PM

This deploys runtime and system PM in the KXSD9 driver:

- Use the force_runtime_suspend/resume callbacks as system PM
  operations.

- Add buffer prepare/unprepare callbacks to grab the runtime
  PM while we're using buffered reads and put get/put_autosuspend
  in these.

- Insert get/put_autosuspend calls anywhere the IO is used from
  the raw read/write callbacks.

- Move the fullscale setting to be cached in the state container
  so we can restore it properly when coming back from
  system/runtime suspend.

- Set the autosuspend delay to two orders of magnitude that of
  the sensor start-up time (20ms) so we will autosuspend after
  2s.

- Register the callbacks in both the SPI and I2C subdrivers.

Tested with the I2C KXSD9 on the Qualcomm APQ8060 Dragonboard.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

4 files changed, 94 insertions, 2 deletions

diff --git a/drivers/iio/accel/kxsd9-i2c.c b/drivers/iio/accel/kxsd9-i2c.c
index 4aaa27d0aa32..95e20855d2ef 100644
--- a/drivers/iio/accel/kxsd9-i2c.c
+++ b/drivers/iio/accel/kxsd9-i2c.c
@@ -55,6 +55,7 @@ static struct i2c_driver kxsd9_i2c_driver = {
         .driver = {
                 .name   = "kxsd9",
                 .of_match_table = of_match_ptr(kxsd9_of_match),
+                .pm = &kxsd9_dev_pm_ops,
         },
         .probe          = kxsd9_i2c_probe,
         .remove         = kxsd9_i2c_remove,
diff --git a/drivers/iio/accel/kxsd9-spi.c b/drivers/iio/accel/kxsd9-spi.c
index c5af51b7dd7e..b7d0078fd00e 100644
--- a/drivers/iio/accel/kxsd9-spi.c
+++ b/drivers/iio/accel/kxsd9-spi.c
@@ -43,6 +43,7 @@ MODULE_DEVICE_TABLE(spi, kxsd9_spi_id);
 static struct spi_driver kxsd9_spi_driver = {
         .driver = {
                 .name = "kxsd9",
+                .pm = &kxsd9_dev_pm_ops,
         },
         .probe = kxsd9_spi_probe,
         .remove = kxsd9_spi_remove,
diff --git a/drivers/iio/accel/kxsd9.c b/drivers/iio/accel/kxsd9.c
index f18cc9436094..a28163b76e12 100644
--- a/drivers/iio/accel/kxsd9.c
+++ b/drivers/iio/accel/kxsd9.c
@@ -23,6 +23,7 @@
 #include <linux/bitops.h>
 #include <linux/delay.h>
 #include <linux/regulator/consumer.h>
+#include <linux/pm_runtime.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
 #include <linux/iio/buffer.h>
@@ -68,11 +69,13 @@
  * @dev: pointer to the parent device
  * @map: regmap to the device
  * @regs: regulators for this device, VDD and IOVDD
+ * @scale: the current scaling setting
  */
 struct kxsd9_state {
         struct device *dev;
         struct regmap *map;
         struct regulator_bulk_data regs[2];
+        u8 scale;
 };
 
 #define KXSD9_SCALE_2G "0.011978"
@@ -111,6 +114,10 @@ static int kxsd9_write_scale(struct iio_dev *indio_dev, int micro)
                                  i);
         if (ret < 0)
                 goto error_ret;
+
+        /* Cached scale when the sensor is powered down */
+        st->scale = i;
+
 error_ret:
         return ret;
 }
@@ -133,6 +140,9 @@ static int kxsd9_write_raw(struct iio_dev *indio_dev,
                            long mask)
 {
         int ret = -EINVAL;
+        struct kxsd9_state *st = iio_priv(indio_dev);
+
+        pm_runtime_get_sync(st->dev);
 
         if (mask == IIO_CHAN_INFO_SCALE) {
                 /* Check no integer component */
@@ -141,6 +151,9 @@ static int kxsd9_write_raw(struct iio_dev *indio_dev,
                 ret = kxsd9_write_scale(indio_dev, val2);
         }
 
+        pm_runtime_mark_last_busy(st->dev);
+        pm_runtime_put_autosuspend(st->dev);
+
         return ret;
 }
 
@@ -154,6 +167,8 @@ static int kxsd9_read_raw(struct iio_dev *indio_dev,
         __be16 raw_val;
         u16 nval;
 
+        pm_runtime_get_sync(st->dev);
+
         switch (mask) {
         case IIO_CHAN_INFO_RAW:
                 ret = regmap_bulk_read(st->map, chan->address, &raw_val,
@@ -184,6 +199,9 @@ static int kxsd9_read_raw(struct iio_dev *indio_dev,
         }
 
 error_ret:
+        pm_runtime_mark_last_busy(st->dev);
+        pm_runtime_put_autosuspend(st->dev);
+
         return ret;
 };
 
@@ -214,6 +232,32 @@ static irqreturn_t kxsd9_trigger_handler(int irq, void *p)
         return IRQ_HANDLED;
 }
 
+static int kxsd9_buffer_preenable(struct iio_dev *indio_dev)
+{
+        struct kxsd9_state *st = iio_priv(indio_dev);
+
+        pm_runtime_get_sync(st->dev);
+
+        return 0;
+}
+
+static int kxsd9_buffer_postdisable(struct iio_dev *indio_dev)
+{
+        struct kxsd9_state *st = iio_priv(indio_dev);
+
+        pm_runtime_mark_last_busy(st->dev);
+        pm_runtime_put_autosuspend(st->dev);
+
+        return 0;
+}
+
+static const struct iio_buffer_setup_ops kxsd9_buffer_setup_ops = {
+        .preenable = kxsd9_buffer_preenable,
+        .postenable = iio_triggered_buffer_postenable,
+        .predisable = iio_triggered_buffer_predisable,
+        .postdisable = kxsd9_buffer_postdisable,
+};
+
 #define KXSD9_ACCEL_CHAN(axis, index)                                           \
         {                                                               \
                 .type = IIO_ACCEL,                                      \
@@ -285,7 +329,7 @@ static int kxsd9_power_up(struct kxsd9_state *st)
                            KXSD9_CTRL_C_LP_1000HZ |
                            KXSD9_CTRL_C_MOT_LEV |
                            KXSD9_CTRL_C_MOT_LAT |
-                           KXSD9_CTRL_C_FS_2G);
+                           st->scale);
         if (ret)
                 return ret;
 
@@ -369,13 +413,15 @@ int kxsd9_common_probe(struct device *dev,
                 dev_err(dev, "Cannot get regulators\n");
                 return ret;
         }
+        /* Default scaling */
+        st->scale = KXSD9_CTRL_C_FS_2G;
 
         kxsd9_power_up(st);
 
         ret = iio_triggered_buffer_setup(indio_dev,
                                          iio_pollfunc_store_time,
                                          kxsd9_trigger_handler,
-                                         NULL);
+                                         &kxsd9_buffer_setup_ops);
         if (ret) {
                 dev_err(dev, "triggered buffer setup failed\n");
                 goto err_power_down;
@@ -387,6 +433,19 @@ int kxsd9_common_probe(struct device *dev,
 
         dev_set_drvdata(dev, indio_dev);
 
+        /* Enable runtime PM */
+        pm_runtime_get_noresume(dev);
+        pm_runtime_set_active(dev);
+        pm_runtime_enable(dev);
+        /*
+         * Set autosuspend to two orders of magnitude larger than the
+         * start-up time. 20ms start-up time means 2000ms autosuspend,
+         * i.e. 2 seconds.
+         */
+        pm_runtime_set_autosuspend_delay(dev, 2000);
+        pm_runtime_use_autosuspend(dev);
+        pm_runtime_put(dev);
+
         return 0;
 
 err_cleanup_buffer:
@@ -405,12 +464,41 @@ int kxsd9_common_remove(struct device *dev)
 
         iio_triggered_buffer_cleanup(indio_dev);
         iio_device_unregister(indio_dev);
+        pm_runtime_get_sync(dev);
+        pm_runtime_put_noidle(dev);
+        pm_runtime_disable(dev);
         kxsd9_power_down(st);
 
         return 0;
 }
 EXPORT_SYMBOL(kxsd9_common_remove);
 
+#ifdef CONFIG_PM
+static int kxsd9_runtime_suspend(struct device *dev)
+{
+        struct iio_dev *indio_dev = dev_get_drvdata(dev);
+        struct kxsd9_state *st = iio_priv(indio_dev);
+
+        return kxsd9_power_down(st);
+}
+
+static int kxsd9_runtime_resume(struct device *dev)
+{
+        struct iio_dev *indio_dev = dev_get_drvdata(dev);
+        struct kxsd9_state *st = iio_priv(indio_dev);
+
+        return kxsd9_power_up(st);
+}
+#endif /* CONFIG_PM */
+
+const struct dev_pm_ops kxsd9_dev_pm_ops = {
+        SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
+                                pm_runtime_force_resume)
+        SET_RUNTIME_PM_OPS(kxsd9_runtime_suspend,
+                           kxsd9_runtime_resume, NULL)
+};
+EXPORT_SYMBOL(kxsd9_dev_pm_ops);
+
 MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
 MODULE_DESCRIPTION("Kionix KXSD9 driver");
 MODULE_LICENSE("GPL v2");
diff --git a/drivers/iio/accel/kxsd9.h b/drivers/iio/accel/kxsd9.h
index 9c0861f6b838..7e8a28168310 100644
--- a/drivers/iio/accel/kxsd9.h
+++ b/drivers/iio/accel/kxsd9.h
@@ -8,3 +8,5 @@ int kxsd9_common_probe(struct device *dev,
                        struct regmap *map,
                        const char *name);
 int kxsd9_common_remove(struct device *dev);
+
+extern const struct dev_pm_ops kxsd9_dev_pm_ops;