greybus: firmware: Add runtime PM support

This patch implements runtime PM support for firmware management bundle.
This guarantees that the bundle will be active, while the AP or the
Module is trying to exchange any operations over any of the CPorts.

- Firmware Management CPort:

Runtime PM get/put calls are placed around the ioctl calls, which are
all implemented as blocking ioctls.

- Component Authentication CPort:

Runtime PM get/put calls are placed around the ioctl calls, which are
all implemented as blocking ioctls.

- SPI:

Uses the interface provided by spilib.c and runtime PM get/put are
called around connection usage.

- firmware-download:

This is the most tricky one. All operations on this CPort are
initiated from the Module and not from the AP. And the AP needs to do
runtime_pm_get() before any request is received over this CPort.

The module doesn't send any request over this connection, unless the
AP has requested the module over firmware management CPort to download
a firmware package over firmware download CPort.

And so the runtime PM get/put calls around the ioctls in
fw-management.c are sufficient to handle the firmware management CPort
as well.

Signed-off-by: Viresh Kumar <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/staging/greybus/authentication.c

···
 			       unsigned long arg)
 {
 	struct gb_cap *cap = file->private_data;
+	struct gb_bundle *bundle = cap->connection->bundle;
 	int ret = -ENODEV;
 
 	/*
···
 	 * new operations.
 	 */
 	mutex_lock(&cap->mutex);
-	if (!cap->disabled)
-		ret = cap_ioctl(cap, cmd, (void __user *)arg);
+	if (!cap->disabled) {
+		ret = gb_pm_runtime_get_sync(bundle);
+		if (!ret) {
+			ret = cap_ioctl(cap, cmd, (void __user *)arg);
+			gb_pm_runtime_put_autosuspend(bundle);
+		}
+	}
 	mutex_unlock(&cap->mutex);
 
 	return ret;

drivers/staging/greybus/fw-core.c

···
 	struct gb_connection	*cap_connection;
 };
 
+#ifndef SPI_CORE_SUPPORT_PM
+static int fw_spi_prepare_transfer_hardware(struct device *dev)
+{
+	return gb_pm_runtime_get_sync(to_gb_bundle(dev));
+}
+
+static void fw_spi_unprepare_transfer_hardware(struct device *dev)
+{
+	gb_pm_runtime_put_autosuspend(to_gb_bundle(dev));
+}
+
+static struct spilib_ops __spilib_ops = {
+	.prepare_transfer_hardware = fw_spi_prepare_transfer_hardware,
+	.unprepare_transfer_hardware = fw_spi_unprepare_transfer_hardware,
+};
+
+static struct spilib_ops *spilib_ops = &__spilib_ops;
+#else
+static struct spilib_ops *spilib_ops = NULL;
+#endif
+
 struct gb_connection *to_fw_mgmt_connection(struct device *dev)
 {
 	struct gb_fw_core *fw_core = dev_get_drvdata(dev);
···
 	if (ret)
 		return ret;
 
-	ret = gb_spilib_master_init(connection, &connection->bundle->dev, NULL);
+	ret = gb_spilib_master_init(connection, &connection->bundle->dev,
+				    spilib_ops);
 	if (ret) {
 		gb_connection_disable(connection);
 		return ret;
···
 
 	greybus_set_drvdata(bundle, fw_core);
 
+	gb_pm_runtime_put_autosuspend(bundle);
+
 	return 0;
 
 err_exit_connections:
···
 static void gb_fw_core_disconnect(struct gb_bundle *bundle)
 {
 	struct gb_fw_core *fw_core = greybus_get_drvdata(bundle);
+	int ret;
+
+	ret = gb_pm_runtime_get_sync(bundle);
+	if (ret)
+		gb_pm_runtime_get_noresume(bundle);
 
 	gb_fw_mgmt_connection_exit(fw_core->mgmt_connection);
 	gb_cap_connection_exit(fw_core->cap_connection);

drivers/staging/greybus/fw-management.c

···
 				   unsigned long arg)
 {
 	struct fw_mgmt *fw_mgmt = file->private_data;
+	struct gb_bundle *bundle = fw_mgmt->connection->bundle;
 	int ret = -ENODEV;
 
 	/*
···
 	 * new operations.
 	 */
 	mutex_lock(&fw_mgmt->mutex);
-	if (!fw_mgmt->disabled)
-		ret = fw_mgmt_ioctl(fw_mgmt, cmd, (void __user *)arg);
+	if (!fw_mgmt->disabled) {
+		ret = gb_pm_runtime_get_sync(bundle);
+		if (!ret) {
+			ret = fw_mgmt_ioctl(fw_mgmt, cmd, (void __user *)arg);
+			gb_pm_runtime_put_autosuspend(bundle);
+		}
+	}
 	mutex_unlock(&fw_mgmt->mutex);
 
 	return ret;