Bluetooth: btintel_pcie: Add support for _suspend() / _resume()

This patch implements _suspend() and _resume() functions for the
Bluetooth controller. When the system enters a suspended state, the
driver notifies the controller to perform necessary housekeeping tasks
by writing to the sleep control register and waits for an alive
interrupt. The firmware raises the alive interrupt when it has
transitioned to the D3 state. The same flow occurs when the system
resumes.

Command to test host initiated wakeup after 60 seconds
sudo rtcwake -m mem -s 60

dmesg log (tested on Whale Peak2 on Panther Lake platform)
On system suspend:
[Fri Jul 25 11:05:37 2025] Bluetooth: hci0: device entered into d3 state from d0 in 80 us

On system resume:
[Fri Jul 25 11:06:36 2025] Bluetooth: hci0: device entered into d0 state from d3 in 7117 us

Signed-off-by: Chandrashekar Devegowda <chandrashekar.devegowda@intel.com>
Signed-off-by: Kiran K <kiran.k@intel.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

1 files changed, 89 insertions, 0 deletions

diff --git a/drivers/bluetooth/btintel_pcie.c b/drivers/bluetooth/btintel_pcie.c
index d08f59ae7720..b3c197b26e89 100644
--- a/drivers/bluetooth/btintel_pcie.c
+++ b/drivers/bluetooth/btintel_pcie.c
@@ -2574,11 +2574,100 @@ static void btintel_pcie_coredump(struct device *dev)
 }
 #endif
 
+static int btintel_pcie_suspend_late(struct device *dev, pm_message_t mesg)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+	struct btintel_pcie_data *data;
+	ktime_t start;
+	u32 dxstate;
+	int err;
+
+	data = pci_get_drvdata(pdev);
+
+	dxstate = (mesg.event == PM_EVENT_SUSPEND ?
+		   BTINTEL_PCIE_STATE_D3_HOT : BTINTEL_PCIE_STATE_D3_COLD);
+
+	data->gp0_received = false;
+
+	start = ktime_get();
+
+	/* Refer: 6.4.11.7 -> Platform power management */
+	btintel_pcie_wr_sleep_cntrl(data, dxstate);
+	err = wait_event_timeout(data->gp0_wait_q, data->gp0_received,
+				 msecs_to_jiffies(BTINTEL_DEFAULT_INTR_TIMEOUT_MS));
+	if (err == 0) {
+		bt_dev_err(data->hdev,
+			   "Timeout (%u ms) on alive interrupt for D3 entry",
+			   BTINTEL_DEFAULT_INTR_TIMEOUT_MS);
+		return -EBUSY;
+	}
+
+	bt_dev_dbg(data->hdev,
+		   "device entered into d3 state from d0 in %lld us",
+		   ktime_to_us(ktime_get() - start));
+
+	return 0;
+}
+
+static int btintel_pcie_suspend(struct device *dev)
+{
+	return btintel_pcie_suspend_late(dev, PMSG_SUSPEND);
+}
+
+static int btintel_pcie_hibernate(struct device *dev)
+{
+	return btintel_pcie_suspend_late(dev, PMSG_HIBERNATE);
+}
+
+static int btintel_pcie_freeze(struct device *dev)
+{
+	return btintel_pcie_suspend_late(dev, PMSG_FREEZE);
+}
+
+static int btintel_pcie_resume(struct device *dev)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+	struct btintel_pcie_data *data;
+	ktime_t start;
+	int err;
+
+	data = pci_get_drvdata(pdev);
+	data->gp0_received = false;
+
+	start = ktime_get();
+
+	/* Refer: 6.4.11.7 -> Platform power management */
+	btintel_pcie_wr_sleep_cntrl(data, BTINTEL_PCIE_STATE_D0);
+	err = wait_event_timeout(data->gp0_wait_q, data->gp0_received,
+				 msecs_to_jiffies(BTINTEL_DEFAULT_INTR_TIMEOUT_MS));
+	if (err == 0) {
+		bt_dev_err(data->hdev,
+			   "Timeout (%u ms) on alive interrupt for D0 entry",
+			   BTINTEL_DEFAULT_INTR_TIMEOUT_MS);
+		return -EBUSY;
+	}
+
+	bt_dev_dbg(data->hdev,
+		    "device entered into d0 state from d3 in %lld us",
+		     ktime_to_us(ktime_get() - start));
+	return 0;
+}
+
+static const struct dev_pm_ops btintel_pcie_pm_ops = {
+	.suspend = btintel_pcie_suspend,
+	.resume = btintel_pcie_resume,
+	.freeze = btintel_pcie_freeze,
+	.thaw = btintel_pcie_resume,
+	.poweroff = btintel_pcie_hibernate,
+	.restore = btintel_pcie_resume,
+};
+
 static struct pci_driver btintel_pcie_driver = {
 	.name = KBUILD_MODNAME,
 	.id_table = btintel_pcie_table,
 	.probe = btintel_pcie_probe,
 	.remove = btintel_pcie_remove,
+	.driver.pm = pm_sleep_ptr(&btintel_pcie_pm_ops),
 #ifdef CONFIG_DEV_COREDUMP
 	.driver.coredump = btintel_pcie_coredump
 #endif