[PATCH 11/17] i3c: mipi-i3c-hci: Add DMA suspend and resume support

[Adrian Hunter]

Introduce helper functions to suspend and resume DMA operations.  These
are required to prepare for upcoming Runtime PM support, ensuring that
DMA state is properly managed during power transitions.

Signed-off-by: Adrian Hunter <adrian.hunter at intel.com>
---
 drivers/i3c/master/mipi-i3c-hci/dma.c | 25 +++++++++++++++++++++++++
 drivers/i3c/master/mipi-i3c-hci/hci.h |  2 ++
 2 files changed, 27 insertions(+)

diff --git a/drivers/i3c/master/mipi-i3c-hci/dma.c b/drivers/i3c/master/mipi-i3c-hci/dma.c
index d0fc245f8e8f..6be97f0782d8 100644
--- a/drivers/i3c/master/mipi-i3c-hci/dma.c
+++ b/drivers/i3c/master/mipi-i3c-hci/dma.c
@@ -275,6 +275,29 @@ static void hci_dma_init_rings(struct i3c_hci *hci)
 		hci_dma_init_rh(hci, &rings->headers[i], i);
 }
 
+static void hci_dma_suspend(struct i3c_hci *hci)
+{
+	struct hci_rings_data *rings = hci->io_data;
+	int n = rings ? rings->total : 0;
+
+	for (int i = 0; i < n; i++) {
+		struct hci_rh_data *rh = &rings->headers[i];
+
+		rh_reg_write(INTR_SIGNAL_ENABLE, 0);
+		rh_reg_write(RING_CONTROL, 0);
+	}
+
+	i3c_hci_sync_irq_inactive(hci);
+}
+
+static void hci_dma_resume(struct i3c_hci *hci)
+{
+	struct hci_rings_data *rings = hci->io_data;
+
+	if (rings)
+		hci_dma_init_rings(hci);
+}
+
 static int hci_dma_init(struct i3c_hci *hci)
 {
 	struct hci_rings_data *rings;
@@ -865,4 +888,6 @@ const struct hci_io_ops mipi_i3c_hci_dma = {
 	.request_ibi		= hci_dma_request_ibi,
 	.free_ibi		= hci_dma_free_ibi,
 	.recycle_ibi_slot	= hci_dma_recycle_ibi_slot,
+	.suspend		= hci_dma_suspend,
+	.resume			= hci_dma_resume,
 };
diff --git a/drivers/i3c/master/mipi-i3c-hci/hci.h b/drivers/i3c/master/mipi-i3c-hci/hci.h
index aa8a03594e64..38f927685d3b 100644
--- a/drivers/i3c/master/mipi-i3c-hci/hci.h
+++ b/drivers/i3c/master/mipi-i3c-hci/hci.h
@@ -125,6 +125,8 @@ struct hci_io_ops {
 				struct i3c_ibi_slot *slot);
 	int (*init)(struct i3c_hci *hci);
 	void (*cleanup)(struct i3c_hci *hci);
+	void (*suspend)(struct i3c_hci *hci);
+	void (*resume)(struct i3c_hci *hci);
 };
 
 extern const struct hci_io_ops mipi_i3c_hci_pio;
-- 
2.51.0