[PATCH 2/2] Bluetooth: hci_bcm: Add suspend/resume runtime PM functions

[Frederic Danis <frederic.danis@linux.intel.com>]

Adds autosuspend runtime functionality to BCM UART driver.
Autosuspend is enabled at end of bcm_setup.

Change some CONFIG_PM_SLEEP to CONFIG_PM as hu and is_suspended parameters
are used during runtime PM callbacks.

Replace SpinLock by Mutex to be able to use it in sleepable context.
Add a work queue to be able to perform pm_runtime commands during bcm_recv
which is called by hci_uart_tty_receive() under spinlock.

Signed-off-by: Frederic Danis <frederic.danis@linux.intel.com>
---
 drivers/bluetooth/hci_bcm.c | 210 +++++++++++++++++++++++++++++++++-----------
 1 file changed, 158 insertions(+), 52 deletions(-)

diff --git a/drivers/bluetooth/hci_bcm.c b/drivers/bluetooth/hci_bcm.c
index 1440a56..488c812 100644
--- a/drivers/bluetooth/hci_bcm.c
+++ b/drivers/bluetooth/hci_bcm.c
@@ -32,6 +32,7 @@
 #include <linux/gpio/consumer.h>
 #include <linux/tty.h>
 #include <linux/interrupt.h>
+#include <linux/pm_runtime.h>
 
 #include <net/bluetooth/bluetooth.h>
 #include <net/bluetooth/hci_core.h>
@@ -42,6 +43,8 @@
 #define BCM_NO_FIX		0
 #define BCM_FIX_ACPI_IRQ	1
 
+#define BCM_AUTOSUSPEND_DELAY	5000 /* default autosleep delay */
+
 struct bcm_device {
 	struct list_head	list;
 
@@ -57,7 +60,7 @@ struct bcm_device {
 
 	u32			init_speed;
 
-#ifdef CONFIG_PM_SLEEP
+#ifdef CONFIG_PM
 	struct hci_uart		*hu;
 	bool			is_suspended; /* suspend/resume flag */
 	int			irq;
@@ -70,10 +73,11 @@ struct bcm_data {
 	struct sk_buff_head	txq;
 
 	struct bcm_device	*dev;
+	struct work_struct	pm_work;
 };
 
 /* List of BCM BT UART devices */
-static DEFINE_SPINLOCK(bcm_device_lock);
+static DEFINE_MUTEX(bcm_device_lock);
 static LIST_HEAD(bcm_device_list);
 
 static int bcm_set_baudrate(struct hci_uart *hu, unsigned int speed)
@@ -163,7 +167,7 @@ static const struct bcm_set_sleep_mode default_sleep_params = {
 	.bt_wake_active = 1,	/* BT_WAKE active mode: 1 = high, 0 = low */
 	.host_wake_active = 0,	/* HOST_WAKE active mode: 1 = high, 0 = low */
 	.allow_host_sleep = 1,	/* Allow host sleep in SCO flag */
-	.combine_modes = 0,	/* Combine sleep and LPM flag */
+	.combine_modes = 1,	/* Combine sleep and LPM flag */
 	.tristate_control = 0,	/* Allow tri-state control of UART tx flag */
 	/* Irrelevant USB flags */
 	.usb_auto_sleep = 0,
@@ -196,6 +200,19 @@ static int bcm_setup_sleep(struct hci_uart *hu)
 	return 0;
 }
 
+static void bcm_pm_runtime_work(struct work_struct *work)
+{
+	struct bcm_data *bcm = container_of(work, struct bcm_data, pm_work);
+
+	mutex_lock(&bcm_device_lock);
+	if (bcm_device_exists(bcm->dev)) {
+		pm_runtime_get_sync(&bcm->dev->pdev->dev);
+		pm_runtime_mark_last_busy(&bcm->dev->pdev->dev);
+		pm_runtime_put_autosuspend(&bcm->dev->pdev->dev);
+	}
+	mutex_unlock(&bcm_device_lock);
+}
+
 static int bcm_open(struct hci_uart *hu)
 {
 	struct bcm_data *bcm;
@@ -211,7 +228,7 @@ static int bcm_open(struct hci_uart *hu)
 
 	hu->priv = bcm;
 
-	spin_lock(&bcm_device_lock);
+	mutex_lock(&bcm_device_lock);
 	list_for_each(p, &bcm_device_list) {
 		struct bcm_device *dev = list_entry(p, struct bcm_device, list);
 
@@ -222,17 +239,19 @@ static int bcm_open(struct hci_uart *hu)
 		if (hu->tty->dev->parent == dev->pdev->dev.parent) {
 			bcm->dev = dev;
 			hu->init_speed = dev->init_speed;
-#ifdef CONFIG_PM_SLEEP
+#ifdef CONFIG_PM
 			dev->hu = hu;
 #endif
 			break;
 		}
 	}
 
-	if (bcm->dev)
+	if (bcm->dev) {
 		bcm_gpio_set_power(bcm->dev, true);
+		INIT_WORK(&bcm->pm_work, bcm_pm_runtime_work);
+	}
 
-	spin_unlock(&bcm_device_lock);
+	mutex_unlock(&bcm_device_lock);
 
 	return 0;
 }
@@ -245,18 +264,23 @@ static int bcm_close(struct hci_uart *hu)
 	BT_DBG("hu %p", hu);
 
 	/* Protect bcm->dev against removal of the device or driver */
-	spin_lock(&bcm_device_lock);
+	mutex_lock(&bcm_device_lock);
 	if (bcm_device_exists(bdev)) {
 		bcm_gpio_set_power(bdev, false);
-#ifdef CONFIG_PM_SLEEP
+#ifdef CONFIG_PM
 		bdev->hu = NULL;
 		if (device_can_wakeup(&bdev->pdev->dev)) {
 			devm_free_irq(&bdev->pdev->dev, bdev->irq, bdev);
 			device_init_wakeup(&bdev->pdev->dev, false);
 		}
+
+		pm_runtime_disable(&bdev->pdev->dev);
+		pm_runtime_set_suspended(&bdev->pdev->dev);
 #endif
 	}
-	spin_unlock(&bcm_device_lock);
+	mutex_unlock(&bcm_device_lock);
+
+	cancel_work_sync(&bcm->pm_work);
 
 	skb_queue_purge(&bcm->txq);
 	kfree_skb(bcm->rx_skb);
@@ -283,12 +307,16 @@ static irqreturn_t bcm_host_wake(int irq, void *data)
 
 	BT_DBG("Host wake IRQ for %s", dev->name);
 
+	pm_runtime_get(&dev->pdev->dev);
+	pm_runtime_mark_last_busy(&dev->pdev->dev);
+	pm_runtime_put_autosuspend(&dev->pdev->dev);
+
 	return IRQ_HANDLED;
 }
 
 static int bcm_setup(struct hci_uart *hu)
 {
-#ifdef CONFIG_PM_SLEEP
+#ifdef CONFIG_PM
 	struct bcm_data *bcm = hu->priv;
 	struct bcm_device *bdev = bcm->dev;
 #endif
@@ -351,7 +379,7 @@ finalize:
 		return err;
 
 	/* If it is not a platform device, do not enable PM functionalities */
-	spin_lock(&bcm_device_lock);
+	mutex_lock(&bcm_device_lock);
 	if (!bcm_device_exists(bdev))
 		goto unlock;
 
@@ -363,10 +391,16 @@ finalize:
 			goto unlock;
 
 		device_init_wakeup(&bdev->pdev->dev, true);
+
+		pm_runtime_set_autosuspend_delay(&bdev->pdev->dev,
+						 BCM_AUTOSUSPEND_DELAY);
+		pm_runtime_use_autosuspend(&bdev->pdev->dev);
+		pm_runtime_set_active(&bdev->pdev->dev);
+		pm_runtime_enable(&bdev->pdev->dev);
 	}
 
 unlock:
-	spin_unlock(&bcm_device_lock);
+	mutex_unlock(&bcm_device_lock);
 
 	err = bcm_setup_sleep(hu);
 #endif
@@ -383,6 +417,7 @@ static const struct h4_recv_pkt bcm_recv_pkts[] = {
 static int bcm_recv(struct hci_uart *hu, const void *data, int count)
 {
 	struct bcm_data *bcm = hu->priv;
+	int ret;
 
 	if (!test_bit(HCI_UART_REGISTERED, &hu->flags))
 		return -EUNATCH;
@@ -390,13 +425,20 @@ static int bcm_recv(struct hci_uart *hu, const void *data, int count)
 	bcm->rx_skb = h4_recv_buf(hu->hdev, bcm->rx_skb, data, count,
 				  bcm_recv_pkts, ARRAY_SIZE(bcm_recv_pkts));
 	if (IS_ERR(bcm->rx_skb)) {
-		int err = PTR_ERR(bcm->rx_skb);
-		BT_ERR("%s: Frame reassembly failed (%d)", hu->hdev->name, err);
+		ret = PTR_ERR(bcm->rx_skb);
+		BT_ERR("%s: Frame reassembly failed (%d)", hu->hdev->name, ret);
 		bcm->rx_skb = NULL;
-		return err;
-	}
+	} else
+		ret = count;
 
-	return count;
+	/* mutex_lock/unlock can not be used here as this function is called
+	 * from hci_uart_tty_receive under spinlock.
+	 * Defer pm_runtime_* calls to work queue
+	 */
+	if (bcm->dev)
+		schedule_work(&bcm->pm_work);
+
+	return ret;
 }
 
 static int bcm_enqueue(struct hci_uart *hu, struct sk_buff *skb)
@@ -415,10 +457,89 @@ static int bcm_enqueue(struct hci_uart *hu, struct sk_buff *skb)
 static struct sk_buff *bcm_dequeue(struct hci_uart *hu)
 {
 	struct bcm_data *bcm = hu->priv;
+	struct sk_buff *skb = NULL;
+	struct bcm_device *bdev = NULL;
+
+	mutex_lock(&bcm_device_lock);
+
+	if (bcm_device_exists(bcm->dev)) {
+		bdev = bcm->dev;
+		pm_runtime_get_sync(&bdev->pdev->dev);
+	}
+
+	skb = skb_dequeue(&bcm->txq);
+
+	if (bdev) {
+		pm_runtime_mark_last_busy(&bdev->pdev->dev);
+		pm_runtime_put_autosuspend(&bdev->pdev->dev);
+	}
+
+	mutex_unlock(&bcm_device_lock);
+
+	return skb;
+}
+
+#ifdef CONFIG_PM
+static void __bcm_suspend(struct bcm_device *dev)
+{
+	if (!dev->is_suspended) {
+		hci_uart_set_flow_control(dev->hu, true);
+
+		/* Once this returns, driver suspends BT via GPIO */
+		dev->is_suspended = true;
+	}
+
+	/* Suspend the device */
+	if (dev->device_wakeup) {
+		gpiod_set_value(dev->device_wakeup, false);
+		BT_DBG("suspend, delaying 15 ms");
+		mdelay(15);
+	}
+}
+
+static void __bcm_resume(struct bcm_device *dev)
+{
+	if (dev->device_wakeup) {
+		gpiod_set_value(dev->device_wakeup, true);
+		BT_DBG("resume, delaying 15 ms");
+		mdelay(15);
+	}
+
+	/* When this executes, the device has woken up already */
+	if (dev->is_suspended) {
+		dev->is_suspended = false;
+
+		hci_uart_set_flow_control(dev->hu, false);
+	}
+}
+
+static int bcm_runtime_suspend(struct device *dev)
+{
+	struct bcm_device *bdev = platform_get_drvdata(to_platform_device(dev));
+
+	BT_DBG("");
 
-	return skb_dequeue(&bcm->txq);
+	mutex_lock(&bcm_device_lock);
+	__bcm_suspend(bdev);
+	mutex_unlock(&bcm_device_lock);
+
+	return 0;
 }
 
+static int bcm_runtime_resume(struct device *dev)
+{
+	struct bcm_device *bdev = platform_get_drvdata(to_platform_device(dev));
+
+	BT_DBG("");
+
+	mutex_lock(&bcm_device_lock);
+	__bcm_resume(bdev);
+	mutex_unlock(&bcm_device_lock);
+
+	return 0;
+}
+#endif
+
 #ifdef CONFIG_PM_SLEEP
 /* Platform suspend callback */
 static int bcm_suspend(struct device *dev)
@@ -428,24 +549,13 @@ static int bcm_suspend(struct device *dev)
 
 	BT_DBG("suspend (%p): is_suspended %d", bdev, bdev->is_suspended);
 
-	spin_lock(&bcm_device_lock);
+	mutex_lock(&bcm_device_lock);
 
 	if (!bdev->hu)
 		goto unlock;
 
-	if (!bdev->is_suspended) {
-		hci_uart_set_flow_control(bdev->hu, true);
-
-		/* Once this callback returns, driver suspends BT via GPIO */
-		bdev->is_suspended = true;
-	}
-
-	/* Suspend the device */
-	if (bdev->device_wakeup) {
-		gpiod_set_value(bdev->device_wakeup, false);
-		BT_DBG("suspend, delaying 15 ms");
-		mdelay(15);
-	}
+	if (pm_runtime_active(dev))
+		__bcm_suspend(bdev);
 
 	if (device_may_wakeup(&bdev->pdev->dev)) {
 		error = enable_irq_wake(bdev->irq);
@@ -454,7 +564,7 @@ static int bcm_suspend(struct device *dev)
 	}
 
 unlock:
-	spin_unlock(&bcm_device_lock);
+	mutex_unlock(&bcm_device_lock);
 
 	return 0;
 }
@@ -466,7 +576,7 @@ static int bcm_resume(struct device *dev)
 
 	BT_DBG("resume (%p): is_suspended %d", bdev, bdev->is_suspended);
 
-	spin_lock(&bcm_device_lock);
+	mutex_lock(&bcm_device_lock);
 
 	if (!bdev->hu)
 		goto unlock;
@@ -476,21 +586,14 @@ static int bcm_resume(struct device *dev)
 		BT_DBG("BCM irq: disabled");
 	}
 
-	if (bdev->device_wakeup) {
-		gpiod_set_value(bdev->device_wakeup, true);
-		BT_DBG("resume, delaying 15 ms");
-		mdelay(15);
-	}
-
-	/* When this callback executes, the device has woken up already */
-	if (bdev->is_suspended) {
-		bdev->is_suspended = false;
+	__bcm_resume(bdev);
 
-		hci_uart_set_flow_control(bdev->hu, false);
-	}
+	pm_runtime_disable(dev);
+	pm_runtime_set_active(dev);
+	pm_runtime_enable(dev);
 
 unlock:
-	spin_unlock(&bcm_device_lock);
+	mutex_unlock(&bcm_device_lock);
 
 	return 0;
 }
@@ -635,9 +738,9 @@ static int bcm_probe(struct platform_device *pdev)
 	dev_info(&pdev->dev, "%s device registered.\n", dev->name);
 
 	/* Place this instance on the device list */
-	spin_lock(&bcm_device_lock);
+	mutex_lock(&bcm_device_lock);
 	list_add_tail(&dev->list, &bcm_device_list);
-	spin_unlock(&bcm_device_lock);
+	mutex_unlock(&bcm_device_lock);
 
 	bcm_gpio_set_power(dev, false);
 
@@ -648,9 +751,9 @@ static int bcm_remove(struct platform_device *pdev)
 {
 	struct bcm_device *dev = platform_get_drvdata(pdev);
 
-	spin_lock(&bcm_device_lock);
+	mutex_lock(&bcm_device_lock);
 	list_del(&dev->list);
-	spin_unlock(&bcm_device_lock);
+	mutex_unlock(&bcm_device_lock);
 
 	acpi_dev_remove_driver_gpios(ACPI_COMPANION(&pdev->dev));
 
@@ -684,7 +787,10 @@ MODULE_DEVICE_TABLE(acpi, bcm_acpi_match);
 #endif
 
 /* Platform suspend and resume callbacks */
-static SIMPLE_DEV_PM_OPS(bcm_pm_ops, bcm_suspend, bcm_resume);
+static const struct dev_pm_ops bcm_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(bcm_suspend, bcm_resume)
+	SET_RUNTIME_PM_OPS(bcm_runtime_suspend, bcm_runtime_resume, NULL)
+};
 
 static struct platform_driver bcm_driver = {
 	.probe = bcm_probe,
-- 
1.9.1