iio: cros_ec: Relax sampling frequency before suspending

If an application set a tight sampling frequency, given the interrupt
use is a wakeup source, suspend will not happen: the kernel will receive
a wake up interrupt and will cancel the suspend process.

Given cros_ec sensors type is non wake up, this patch adds prepare and
complete callbacks to set 1s sampling period just before suspend. This
ensures the sensor hub will not be a source of interrupt during the
suspend process.

Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/common/cros_ec_sensors/cros_ec_sensors.c

@@ -289,6 +289,7 @@ MODULE_DEVICE_TABLE(platform, cros_ec_sensors_ids);
 static struct platform_driver cros_ec_sensors_platform_driver = {
 	.driver = {
 		.name	= "cros-ec-sensors",
+		.pm	= &cros_ec_sensors_pm_ops,
 	},
 	.probe		= cros_ec_sensors_probe,
 	.id_table	= cros_ec_sensors_ids,

drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c

@@ -446,5 +446,54 @@ int cros_ec_sensors_core_write(struct cros_ec_sensors_core_state *st,
 }
 EXPORT_SYMBOL_GPL(cros_ec_sensors_core_write);
 
+static int __maybe_unused cros_ec_sensors_prepare(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
+	struct cros_ec_sensors_core_state *st = iio_priv(indio_dev);
+
+	if (st->curr_sampl_freq == 0)
+		return 0;
+
+	/*
+	 * If the sensors are sampled at high frequency, we will not be able to
+	 * sleep. Set sampling to a long period if necessary.
+	 */
+	if (st->curr_sampl_freq < CROS_EC_MIN_SUSPEND_SAMPLING_FREQUENCY) {
+		mutex_lock(&st->cmd_lock);
+		st->param.cmd = MOTIONSENSE_CMD_EC_RATE;
+		st->param.ec_rate.data = CROS_EC_MIN_SUSPEND_SAMPLING_FREQUENCY;
+		cros_ec_motion_send_host_cmd(st, 0);
+		mutex_unlock(&st->cmd_lock);
+	}
+	return 0;
+}
+
+static void __maybe_unused cros_ec_sensors_complete(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
+	struct cros_ec_sensors_core_state *st = iio_priv(indio_dev);
+
+	if (st->curr_sampl_freq == 0)
+		return;
+
+	if (st->curr_sampl_freq < CROS_EC_MIN_SUSPEND_SAMPLING_FREQUENCY) {
+		mutex_lock(&st->cmd_lock);
+		st->param.cmd = MOTIONSENSE_CMD_EC_RATE;
+		st->param.ec_rate.data = st->curr_sampl_freq;
+		cros_ec_motion_send_host_cmd(st, 0);
+		mutex_unlock(&st->cmd_lock);
+	}
+}
+
+const struct dev_pm_ops cros_ec_sensors_pm_ops = {
+#ifdef CONFIG_PM_SLEEP
+	.prepare = cros_ec_sensors_prepare,
+	.complete = cros_ec_sensors_complete
+#endif
+};
+EXPORT_SYMBOL_GPL(cros_ec_sensors_pm_ops);
+
 MODULE_DESCRIPTION("ChromeOS EC sensor hub core functions");
 MODULE_LICENSE("GPL v2");

drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.h

@@ -169,6 +169,8 @@ int cros_ec_sensors_core_write(struct cros_ec_sensors_core_state *st,
 			       struct iio_chan_spec const *chan,
 			       int val, int val2, long mask);
 
+extern const struct dev_pm_ops cros_ec_sensors_pm_ops;
+
 /* List of extended channel specification for all sensors */
 extern const struct iio_chan_spec_ext_info cros_ec_sensors_ext_info[];
 

drivers/iio/light/cros_ec_light_prox.c

@@ -276,6 +276,7 @@ MODULE_DEVICE_TABLE(platform, cros_ec_light_prox_ids);
 static struct platform_driver cros_ec_light_prox_platform_driver = {
 	.driver = {
 		.name	= "cros-ec-light-prox",
+		.pm	= &cros_ec_sensors_pm_ops,
 	},
 	.probe		= cros_ec_light_prox_probe,
 	.id_table	= cros_ec_light_prox_ids,