[PATCH 2/2] Bluetooth: hci_bcm4377: probe again after a resume through firmware

[Andre Eikmeyer <dev@deq.rocks>]

The BCM4377 is powered off during ACPI S3 and loses its firmware. On
resume the driver only unquiesces it, so every command times out.

When the platform firmware handled the resume, probe the controller
again from a work item and skip the ring teardown messages to the lost
firmware.

Signed-off-by: Andre Eikmeyer <dev@deq.rocks>
---
 drivers/bluetooth/hci_bcm4377.c | 59 +++++++++++++++++++++++++++++++++
 1 file changed, 59 insertions(+)

diff --git a/drivers/bluetooth/hci_bcm4377.c b/drivers/bluetooth/hci_bcm4377.c
index da0a48c2be3..4e3630774c0 100644
--- a/drivers/bluetooth/hci_bcm4377.c
+++ b/drivers/bluetooth/hci_bcm4377.c
@@ -16,6 +16,9 @@
 #include <linux/of.h>
 #include <linux/pci.h>
 #include <linux/printk.h>
+#include <linux/slab.h>
+#include <linux/suspend.h>
+#include <linux/workqueue.h>
 
 #include <linux/unaligned.h>
 
@@ -566,6 +569,9 @@ struct bcm4377_data {
 	struct pci_dev *pdev;
 	struct hci_dev *hdev;
 
+	/* set when the controller lost its firmware during system sleep */
+	bool fw_lost;
+
 	void __iomem *bar0;
 	void __iomem *bar2;
 
@@ -1017,6 +1023,11 @@ static int bcm4377_destroy_completion_ring(struct bcm4377_data *bcm4377,
 	struct bcm4377_destroy_completion_ring_msg msg;
 	int ret;
 
+	if (bcm4377->fw_lost) {
+		ring->enabled = false;
+		return 0;
+	}
+
 	memset(&msg, 0, sizeof(msg));
 	msg.msg_type = BCM4377_CONTROL_MSG_DESTROY_COMPLETION_RING;
 	msg.ring_id = cpu_to_le16(ring->ring_id);
@@ -1107,6 +1118,11 @@ static int bcm4377_destroy_transfer_ring(struct bcm4377_data *bcm4377,
 	struct bcm4377_destroy_transfer_ring_msg msg;
 	int ret;
 
+	if (bcm4377->fw_lost) {
+		ring->enabled = false;
+		return 0;
+	}
+
 	memset(&msg, 0, sizeof(msg));
 	msg.msg_type = BCM4377_CONTROL_MSG_DESTROY_XFER_RING;
 	msg.ring_id = cpu_to_le16(ring->ring_id);
@@ -2432,11 +2448,54 @@ static int bcm4377_suspend(struct device *dev)
 	return 0;
 }
 
+struct bcm4377_reprobe {
+	struct work_struct work;
+	struct pci_dev *pdev;
+};
+
+static void bcm4377_reprobe_work(struct work_struct *work)
+{
+	struct bcm4377_reprobe *reprobe =
+		container_of(work, struct bcm4377_reprobe, work);
+	int ret;
+
+	/*
+	 * Probing stays blocked until the system resume completes, the driver
+	 * core then retries the deferred probe.
+	 */
+	ret = device_reprobe(&reprobe->pdev->dev);
+	if (ret && ret != -EPROBE_DEFER)
+		dev_err(&reprobe->pdev->dev, "re-probe after resume failed (%d)\n",
+			ret);
+
+	pci_dev_put(reprobe->pdev);
+	kfree(reprobe);
+}
+
 static int bcm4377_resume(struct device *dev)
 {
 	struct pci_dev *pdev = to_pci_dev(dev);
 	struct bcm4377_data *bcm4377 = pci_get_drvdata(pdev);
 
+	/*
+	 * The controller is powered off when the platform firmware handles
+	 * the system sleep, as with ACPI S3 on x86 Macs, and comes back
+	 * without its firmware. Probe it again.
+	 */
+	if (pm_resume_via_firmware()) {
+		struct bcm4377_reprobe *reprobe;
+
+		reprobe = kzalloc_obj(*reprobe);
+		if (!reprobe)
+			return -ENOMEM;
+
+		bcm4377->fw_lost = true;
+		reprobe->pdev = pci_dev_get(pdev);
+		INIT_WORK(&reprobe->work, bcm4377_reprobe_work);
+		schedule_work(&reprobe->work);
+		return 0;
+	}
+
 	iowrite32(BCM4377_BAR0_SLEEP_CONTROL_UNQUIESCE,
 		  bcm4377->bar0 + BCM4377_BAR0_SLEEP_CONTROL);