Bluetooth: hci_intel: Add runtime PM support

Implement runtime PM suspend/resume callbacks.
If LPM supported, controller is put into supsend after a delay of
inactivity (1s). Inactivity is based on LPM idle notification and
host TX traffic.
Signed-off-by: Loic Poulain <loic.poulain@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

drivers/bluetooth/hci_intel.c

@@ -32,6 +32,7 @@
 #include <linux/gpio/consumer.h>
 #include <linux/acpi.h>
 #include <linux/interrupt.h>
+#include <linux/pm_runtime.h>
 
 #include <net/bluetooth/bluetooth.h>
 #include <net/bluetooth/hci_core.h>
@@ -58,6 +59,8 @@
 #define LPM_OP_SUSPEND_ACK 0x02
 #define LPM_OP_RESUME_ACK 0x03
 
+#define LPM_SUSPEND_DELAY_MS 1000
+
 struct hci_lpm_pkt {
 	__u8 opcode;
 	__u8 dlen;
@@ -79,6 +82,8 @@ static DEFINE_MUTEX(intel_device_list_lock);
 struct intel_data {
 	struct sk_buff *rx_skb;
 	struct sk_buff_head txq;
+	struct work_struct busy_work;
+	struct hci_uart *hu;
 	unsigned long flags;
 };
 
@@ -284,6 +289,11 @@ static irqreturn_t intel_irq(int irq, void *dev_id)
 		intel_lpm_host_wake(idev->hu);
 	mutex_unlock(&idev->hu_lock);
 
+	/* Host/Controller are now LPM resumed, trigger a new delayed suspend */
+	pm_runtime_get(&idev->pdev->dev);
+	pm_runtime_mark_last_busy(&idev->pdev->dev);
+	pm_runtime_put_autosuspend(&idev->pdev->dev);
+
 	return IRQ_HANDLED;
 }
 
@@ -339,9 +349,17 @@ static int intel_set_power(struct hci_uart *hu, bool powered)
 			}
 
 			device_wakeup_enable(&idev->pdev->dev);
+
+			pm_runtime_set_active(&idev->pdev->dev);
+			pm_runtime_use_autosuspend(&idev->pdev->dev);
+			pm_runtime_set_autosuspend_delay(&idev->pdev->dev,
+							 LPM_SUSPEND_DELAY_MS);
+			pm_runtime_enable(&idev->pdev->dev);
 		} else if (!powered && device_may_wakeup(&idev->pdev->dev)) {
 			devm_free_irq(&idev->pdev->dev, idev->irq, idev);
 			device_wakeup_disable(&idev->pdev->dev);
+
+			pm_runtime_disable(&idev->pdev->dev);
 		}
 	}
 
@@ -350,6 +368,28 @@ static int intel_set_power(struct hci_uart *hu, bool powered)
 	return err;
 }
 
+static void intel_busy_work(struct work_struct *work)
+{
+	struct list_head *p;
+	struct intel_data *intel = container_of(work, struct intel_data,
+						busy_work);
+
+	/* Link is busy, delay the suspend */
+	mutex_lock(&intel_device_list_lock);
+	list_for_each(p, &intel_device_list) {
+		struct intel_device *idev = list_entry(p, struct intel_device,
+						       list);
+
+		if (intel->hu->tty->dev->parent == idev->pdev->dev.parent) {
+			pm_runtime_get(&idev->pdev->dev);
+			pm_runtime_mark_last_busy(&idev->pdev->dev);
+			pm_runtime_put_autosuspend(&idev->pdev->dev);
+			break;
+		}
+	}
+	mutex_unlock(&intel_device_list_lock);
+}
+
 static int intel_open(struct hci_uart *hu)
 {
 	struct intel_data *intel;
@@ -361,6 +401,9 @@ static int intel_open(struct hci_uart *hu)
 		return -ENOMEM;
 
 	skb_queue_head_init(&intel->txq);
+	INIT_WORK(&intel->busy_work, intel_busy_work);
+
+	intel->hu = hu;
 
 	hu->priv = intel;
 
@@ -376,6 +419,8 @@ static int intel_close(struct hci_uart *hu)
 
 	BT_DBG("hu %p", hu);
 
+	cancel_work_sync(&intel->busy_work);
+
 	intel_set_power(hu, false);
 
 	skb_queue_purge(&intel->txq);
@@ -949,10 +994,12 @@ static void intel_recv_lpm_notify(struct hci_dev *hdev, int value)
 
 	bt_dev_dbg(hdev, "TX idle notification (%d)", value);
 
-	if (value)
+	if (value) {
 		set_bit(STATE_TX_ACTIVE, &intel->flags);
-	else
+		schedule_work(&intel->busy_work);
+	} else {
 		clear_bit(STATE_TX_ACTIVE, &intel->flags);
+	}
 }
 
 static int intel_recv_lpm(struct hci_dev *hdev, struct sk_buff *skb)
@@ -1027,9 +1074,27 @@ static int intel_recv(struct hci_uart *hu, const void *data, int count)
 static int intel_enqueue(struct hci_uart *hu, struct sk_buff *skb)
 {
 	struct intel_data *intel = hu->priv;
+	struct list_head *p;
 
 	BT_DBG("hu %p skb %p", hu, skb);
 
+	/* Be sure our controller is resumed and potential LPM transaction
+	 * completed before enqueuing any packet.
+	 */
+	mutex_lock(&intel_device_list_lock);
+	list_for_each(p, &intel_device_list) {
+		struct intel_device *idev = list_entry(p, struct intel_device,
+						       list);
+
+		if (hu->tty->dev->parent == idev->pdev->dev.parent) {
+			pm_runtime_get_sync(&idev->pdev->dev);
+			pm_runtime_mark_last_busy(&idev->pdev->dev);
+			pm_runtime_put_autosuspend(&idev->pdev->dev);
+			break;
+		}
+	}
+	mutex_unlock(&intel_device_list_lock);
+
 	skb_queue_tail(&intel->txq, skb);
 
 	return 0;
@@ -1103,7 +1168,7 @@ static int intel_acpi_probe(struct intel_device *idev)
 }
 #endif
 
-#ifdef CONFIG_PM_SLEEP
+#ifdef CONFIG_PM
 static int intel_suspend(struct device *dev)
 {
 	struct intel_device *idev = dev_get_drvdata(dev);
@@ -1135,6 +1200,7 @@ static int intel_resume(struct device *dev)
 
 static const struct dev_pm_ops intel_pm_ops = {
 	SET_SYSTEM_SLEEP_PM_OPS(intel_suspend, intel_resume)
+	SET_RUNTIME_PM_OPS(intel_suspend, intel_resume, NULL)
 };
 
 static int intel_probe(struct platform_device *pdev)