iio: accel: mma9551: Add runtime pm support

Add support for runtime pm to reduce the power consumed by the device
when not used.

If CONFIG_PM is not enabled, the device will be powered on at
init and only powered off on system suspend.

If CONFIG_PM is enabled, runtime pm autosuspend is used:
- for raw reads will keep the device on for a specified time
- for events it will keep the device on as long as we have at least
one event active

Signed-off-by: Irina Tirdea <irina.tirdea@intel.com>
Reviewed-by: Vlad Dogaru <vlad.dogaru@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

1 files changed, 139 insertions, 23 deletions

diff --git a/drivers/iio/accel/mma9551.c b/drivers/iio/accel/mma9551.c
index 6563e267b8ae..f1a5a06a0726 100644
--- a/drivers/iio/accel/mma9551.c
+++ b/drivers/iio/accel/mma9551.c
@@ -22,6 +22,7 @@
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
 #include <linux/iio/events.h>
+#include <linux/pm_runtime.h>
 
 #define MMA9551_DRV_NAME                "mma9551"
 #define MMA9551_IRQ_NAME                "mma9551_event"
@@ -71,6 +72,7 @@ enum mma9551_gpio_pin {
 /* Sleep/Wake application */
 #define MMA9551_SLEEP_CFG               0x06
 #define MMA9551_SLEEP_CFG_SNCEN         BIT(0)
+#define MMA9551_SLEEP_CFG_FLEEN         BIT(1)
 #define MMA9551_SLEEP_CFG_SCHEN         BIT(2)
 
 /* AFE application */
@@ -114,6 +116,9 @@ enum mma9551_tilt_axis {
 #define MMA9551_I2C_READ_RETRIES        5
 #define MMA9551_I2C_READ_DELAY  50      /* us */
 
+#define MMA9551_DEFAULT_SAMPLE_RATE     122     /* Hz */
+#define MMA9551_AUTO_SUSPEND_DELAY_MS   2000
+
 struct mma9551_mbox_request {
         u8 start_mbox;          /* Always 0. */
         u8 app_id;
@@ -387,16 +392,55 @@ static int mma9551_read_version(struct i2c_client *client)
 }
 
 /*
+ * Power on chip and enable doze mode.
  * Use 'false' as the second parameter to cause the device to enter
  * sleep.
  */
-static int mma9551_set_device_state(struct i2c_client *client,
-                                    bool enable)
+static int mma9551_set_device_state(struct i2c_client *client, bool enable)
 {
         return mma9551_update_config_bits(client, MMA9551_APPID_SLEEP_WAKE,
                                           MMA9551_SLEEP_CFG,
-                                          MMA9551_SLEEP_CFG_SNCEN,
-                                          enable ? 0 : MMA9551_SLEEP_CFG_SNCEN);
+                                          MMA9551_SLEEP_CFG_SNCEN |
+                                          MMA9551_SLEEP_CFG_FLEEN |
+                                          MMA9551_SLEEP_CFG_SCHEN,
+                                          enable ? MMA9551_SLEEP_CFG_SCHEN |
+                                          MMA9551_SLEEP_CFG_FLEEN :
+                                          MMA9551_SLEEP_CFG_SNCEN);
+}
+
+static int mma9551_set_power_state(struct i2c_client *client, bool on)
+{
+#ifdef CONFIG_PM
+        int ret;
+
+        if (on)
+                ret = pm_runtime_get_sync(&client->dev);
+        else {
+                pm_runtime_mark_last_busy(&client->dev);
+                ret = pm_runtime_put_autosuspend(&client->dev);
+        }
+
+        if (ret < 0) {
+                dev_err(&client->dev,
+                        "failed to change power state to %d\n", on);
+                if (on)
+                        pm_runtime_put_noidle(&client->dev);
+
+                return ret;
+        }
+#endif
+
+        return 0;
+}
+
+static void mma9551_sleep(int freq)
+{
+        int sleep_val = 1000 / freq;
+
+        if (sleep_val < 20)
+                usleep_range(sleep_val * 1000, 20000);
+        else
+                msleep_interruptible(sleep_val);
 }
 
 static int mma9551_read_incli_chan(struct i2c_client *client,
@@ -424,15 +468,19 @@ static int mma9551_read_incli_chan(struct i2c_client *client,
                 return -EINVAL;
         }
 
+        ret = mma9551_set_power_state(client, true);
+        if (ret < 0)
+                return ret;
+
         ret = mma9551_read_status_byte(client, MMA9551_APPID_TILT,
                                        reg_addr, &angle);
         if (ret < 0)
-                return ret;
+                goto out_poweroff;
 
         ret = mma9551_read_status_byte(client, MMA9551_APPID_TILT,
                                        MMA9551_TILT_QUAD_REG, &quadrant);
         if (ret < 0)
-                return ret;
+                goto out_poweroff;
 
         angle &= ~MMA9551_TILT_ANGFLG;
         quadrant = (quadrant >> quad_shift) & 0x03;
@@ -442,7 +490,11 @@ static int mma9551_read_incli_chan(struct i2c_client *client,
         else
                 *val = angle + 90 * quadrant;
 
-        return IIO_VAL_INT;
+        ret = IIO_VAL_INT;
+
+out_poweroff:
+        mma9551_set_power_state(client, false);
+        return ret;
 }
 
 static int mma9551_read_accel_chan(struct i2c_client *client,
@@ -467,14 +519,22 @@ static int mma9551_read_accel_chan(struct i2c_client *client,
                 return -EINVAL;
         }
 
+        ret = mma9551_set_power_state(client, true);
+        if (ret < 0)
+                return ret;
+
         ret = mma9551_read_status_word(client, MMA9551_APPID_AFE,
                                        reg_addr, &raw_accel);
         if (ret < 0)
-                return ret;
+                goto out_poweroff;
 
         *val = raw_accel;
 
-        return IIO_VAL_INT;
+        ret = IIO_VAL_INT;
+
+out_poweroff:
+        mma9551_set_power_state(client, false);
+        return ret;
 }
 
 static int mma9551_read_raw(struct iio_dev *indio_dev,
@@ -556,6 +616,10 @@ static int mma9551_config_incli_event(struct iio_dev *indio_dev,
                                           MMA9551_APPID_NONE, 0, 0);
                 if (ret < 0)
                         return ret;
+
+                ret = mma9551_set_power_state(data->client, false);
+                if (ret < 0)
+                        return ret;
         } else {
                 int bitnum;
 
@@ -574,11 +638,18 @@ static int mma9551_config_incli_event(struct iio_dev *indio_dev,
                         return -EINVAL;
                 }
 
+
+                ret = mma9551_set_power_state(data->client, true);
+                if (ret < 0)
+                        return ret;
+
                 ret = mma9551_gpio_config(data->client,
                                           (enum mma9551_gpio_pin)mma_axis,
                                           MMA9551_APPID_TILT, bitnum, 0);
-                if (ret < 0)
+                if (ret < 0) {
+                        mma9551_set_power_state(data->client, false);
                         return ret;
+                }
         }
 
         data->event_enabled[mma_axis] = state;
@@ -771,12 +842,7 @@ static int mma9551_init(struct mma9551_data *data)
         if (ret)
                 return ret;
 
-        /* Power on chip and enable doze mode. */
-        return mma9551_update_config_bits(data->client,
-                         MMA9551_APPID_SLEEP_WAKE,
-                         MMA9551_SLEEP_CFG,
-                         MMA9551_SLEEP_CFG_SCHEN | MMA9551_SLEEP_CFG_SNCEN,
-                         MMA9551_SLEEP_CFG_SCHEN);
+        return mma9551_set_device_state(data->client, true);
 }
 
 static int mma9551_gpio_probe(struct iio_dev *indio_dev)
@@ -869,8 +935,19 @@ static int mma9551_probe(struct i2c_client *client,
                 goto out_poweroff;
         }
 
+        ret = pm_runtime_set_active(&client->dev);
+        if (ret < 0)
+                goto out_iio_unregister;
+
+        pm_runtime_enable(&client->dev);
+        pm_runtime_set_autosuspend_delay(&client->dev,
+                                         MMA9551_AUTO_SUSPEND_DELAY_MS);
+        pm_runtime_use_autosuspend(&client->dev);
+
         return 0;
 
+out_iio_unregister:
+        iio_device_unregister(indio_dev);
 out_poweroff:
         mma9551_set_device_state(client, false);
 
@@ -882,6 +959,10 @@ static int mma9551_remove(struct i2c_client *client)
         struct iio_dev *indio_dev = i2c_get_clientdata(client);
         struct mma9551_data *data = iio_priv(indio_dev);
 
+        pm_runtime_disable(&client->dev);
+        pm_runtime_set_suspended(&client->dev);
+        pm_runtime_put_noidle(&client->dev);
+
         iio_device_unregister(indio_dev);
         mutex_lock(&data->mutex);
         mma9551_set_device_state(data->client, false);
@@ -890,37 +971,72 @@ static int mma9551_remove(struct i2c_client *client)
         return 0;
 }
 
+#ifdef CONFIG_PM
+static int mma9551_runtime_suspend(struct device *dev)
+{
+        struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
+        struct mma9551_data *data = iio_priv(indio_dev);
+        int ret;
+
+        mutex_lock(&data->mutex);
+        ret = mma9551_set_device_state(data->client, false);
+        mutex_unlock(&data->mutex);
+        if (ret < 0) {
+                dev_err(&data->client->dev, "powering off device failed\n");
+                return -EAGAIN;
+        }
+
+        return 0;
+}
+
+static int mma9551_runtime_resume(struct device *dev)
+{
+        struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
+        struct mma9551_data *data = iio_priv(indio_dev);
+        int ret;
+
+        ret = mma9551_set_device_state(data->client, true);
+        if (ret < 0)
+                return ret;
+
+        mma9551_sleep(MMA9551_DEFAULT_SAMPLE_RATE);
+
+        return 0;
+}
+#endif
+
 #ifdef CONFIG_PM_SLEEP
 static int mma9551_suspend(struct device *dev)
 {
         struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
         struct mma9551_data *data = iio_priv(indio_dev);
+        int ret;
 
         mutex_lock(&data->mutex);
-        mma9551_set_device_state(data->client, false);
+        ret = mma9551_set_device_state(data->client, false);
         mutex_unlock(&data->mutex);
 
-        return 0;
+        return ret;
 }
 
 static int mma9551_resume(struct device *dev)
 {
         struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
         struct mma9551_data *data = iio_priv(indio_dev);
+        int ret;
 
         mutex_lock(&data->mutex);
-        mma9551_set_device_state(data->client, true);
+        ret = mma9551_set_device_state(data->client, true);
         mutex_unlock(&data->mutex);
 
-        return 0;
+        return ret;
 }
-#else
-#define mma9551_suspend NULL
-#define mma9551_resume NULL
 #endif
 
 static const struct dev_pm_ops mma9551_pm_ops = {
         SET_SYSTEM_SLEEP_PM_OPS(mma9551_suspend, mma9551_resume)
+        SET_RUNTIME_PM_OPS(mma9551_runtime_suspend,
+                           mma9551_runtime_resume, NULL)
 };
 
 static const struct acpi_device_id mma9551_acpi_match[] = {