wifi: ath11k: Register shutdown handler for WCN6750

When the system shuts down, SMMU driver will be stopped and
will not assist in IOVA translations. SMMU driver expects all
of its consumers to shutdown before shutting down itself.
WCN6750 being one of the consumer device should not perform any
DMA operations after the SMMU has shutdown which will otherwise
result in SMMU faults.

SMMU driver will call the shutdown() callback of all its
consumer devices and the consumers shall stop further DMA
activity after the invocation of their respective shutdown()
callbacks.

Register the shutdown() callback to the platform core for WCN6750.
Change will not impact other AHB ath11k devices.

Tested-on: WCN6750 hw1.0 AHB WLAN.MSL.1.0.1-00887-QCAMSLSWPLZ-1
Signed-off-by: Manikanta Pubbisetty <quic_mpubbise@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20220720134710.15523-1-quic_mpubbise@quicinc.com

drivers/net/wireless/ath/ath11k/ahb.c

@@ -1088,20 +1088,10 @@ static int ath11k_ahb_probe(struct platform_device *pdev)
 	return ret;
 }
 
-static int ath11k_ahb_remove(struct platform_device *pdev)
+static void ath11k_ahb_remove_prepare(struct ath11k_base *ab)
 {
-	struct ath11k_base *ab = platform_get_drvdata(pdev);
 	unsigned long left;
 
-	if (test_bit(ATH11K_FLAG_QMI_FAIL, &ab->dev_flags)) {
-		ath11k_ahb_power_down(ab);
-		ath11k_debugfs_soc_destroy(ab);
-		ath11k_qmi_deinit_service(ab);
-		goto qmi_fail;
-	}
-
-	reinit_completion(&ab->driver_recovery);
-
 	if (test_bit(ATH11K_FLAG_RECOVERY, &ab->dev_flags)) {
 		left = wait_for_completion_timeout(&ab->driver_recovery,
 						   ATH11K_AHB_RECOVERY_TIMEOUT);
@@ -1111,19 +1101,60 @@ static int ath11k_ahb_remove(struct platform_device *pdev)
 
 	set_bit(ATH11K_FLAG_UNREGISTERING, &ab->dev_flags);
 	cancel_work_sync(&ab->restart_work);
+	cancel_work_sync(&ab->qmi.event_work);
+}
+
+static void ath11k_ahb_free_resources(struct ath11k_base *ab)
+{
+	struct platform_device *pdev = ab->pdev;
 
-	ath11k_core_deinit(ab);
-qmi_fail:
 	ath11k_ahb_free_irq(ab);
 	ath11k_hal_srng_deinit(ab);
 	ath11k_ahb_fw_resource_deinit(ab);
 	ath11k_ce_free_pipes(ab);
 	ath11k_core_free(ab);
 	platform_set_drvdata(pdev, NULL);
+}
+
+static int ath11k_ahb_remove(struct platform_device *pdev)
+{
+	struct ath11k_base *ab = platform_get_drvdata(pdev);
+
+	if (test_bit(ATH11K_FLAG_QMI_FAIL, &ab->dev_flags)) {
+		ath11k_ahb_power_down(ab);
+		ath11k_debugfs_soc_destroy(ab);
+		ath11k_qmi_deinit_service(ab);
+		goto qmi_fail;
+	}
+
+	ath11k_ahb_remove_prepare(ab);
+	ath11k_core_deinit(ab);
+
+qmi_fail:
+	ath11k_ahb_free_resources(ab);
 
 	return 0;
 }
 
+static void ath11k_ahb_shutdown(struct platform_device *pdev)
+{
+	struct ath11k_base *ab = platform_get_drvdata(pdev);
+
+	/* platform shutdown() & remove() are mutually exclusive.
+	 * remove() is invoked during rmmod & shutdown() during
+	 * system reboot/shutdown.
+	 */
+	ath11k_ahb_remove_prepare(ab);
+
+	if (!(test_bit(ATH11K_FLAG_REGISTERED, &ab->dev_flags)))
+		goto free_resources;
+
+	ath11k_core_deinit(ab);
+
+free_resources:
+	ath11k_ahb_free_resources(ab);
+}
+
 static struct platform_driver ath11k_ahb_driver = {
 	.driver         = {
 		.name   = "ath11k",
@@ -1131,6 +1162,7 @@ static struct platform_driver ath11k_ahb_driver = {
 	},
 	.probe  = ath11k_ahb_probe,
 	.remove = ath11k_ahb_remove,
+	.shutdown = ath11k_ahb_shutdown,
 };
 
 static int ath11k_ahb_init(void)

drivers/net/wireless/ath/ath11k/core.c

@@ -1563,6 +1563,8 @@ static void ath11k_core_pre_reconfigure_recovery(struct ath11k_base *ab)
 
 	wake_up(&ab->wmi_ab.tx_credits_wq);
 	wake_up(&ab->peer_mapping_wq);
+
+	reinit_completion(&ab->driver_recovery);
 }
 
 static void ath11k_core_post_reconfigure_recovery(struct ath11k_base *ab)