wifi: mt76: mt7921e: add pci .shutdown() support

Some combinations of hosts cannnot detect mt7921e after reboot. The
interoperability issue is caused by the status mismatch between host
and chip fw. In such cases, the driver should stop chip activities
and reset chip to default state before reboot.

Suggested-by: angelogioacchino.delregno@collabora.com
Co-developed-by: Deren Wu <deren.wu@mediatek.com>
Signed-off-by: Deren Wu <deren.wu@mediatek.com>
Signed-off-by: Leon Yen <Leon.Yen@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt7921/pci.c

@@ -507,6 +507,21 @@ static int mt7921_pci_resume(struct device *device)
 	return err;
 }
 
+static void mt7921_pci_shutdown(struct pci_dev *pdev)
+{
+	struct mt76_dev *mdev = pci_get_drvdata(pdev);
+	struct mt7921_dev *dev = container_of(mdev, struct mt7921_dev, mt76);
+	struct mt76_connac_pm *pm = &dev->pm;
+
+	cancel_delayed_work_sync(&pm->ps_work);
+	cancel_work_sync(&pm->wake_work);
+
+	/* chip cleanup before reboot */
+	mt7921_mcu_drv_pmctrl(dev);
+	mt7921_dma_cleanup(dev);
+	mt7921_wfsys_reset(dev);
+}
+
 static DEFINE_SIMPLE_DEV_PM_OPS(mt7921_pm_ops, mt7921_pci_suspend, mt7921_pci_resume);
 
 static struct pci_driver mt7921_pci_driver = {
@@ -514,6 +529,7 @@ static struct pci_driver mt7921_pci_driver = {
 	.id_table	= mt7921_pci_device_table,
 	.probe		= mt7921_pci_probe,
 	.remove		= mt7921_pci_remove,
+	.shutdown	= mt7921_pci_shutdown,
 	.driver.pm	= pm_sleep_ptr(&mt7921_pm_ops),
 };