[PATCH RFC 6/7] i3c: mipi-i3c-hci: Factor out i3c_hci_sysdev()

[Adrian Hunter]

The MIPI I3C HCI driver needs to identify the underlying system device
used for DMA mapping and PM operations. The logic for determining that
device is currently embedded in the DMA implementation.

Factor this code out into i3c_hci_sysdev() so it can be shared by other
parts of the driver and keep the device-selection logic in one place.

Signed-off-by: Adrian Hunter <adrian.hunter at intel.com>
---
 drivers/i3c/master/mipi-i3c-hci/core.c | 12 ++++++++++++
 drivers/i3c/master/mipi-i3c-hci/dma.c  | 15 +--------------
 drivers/i3c/master/mipi-i3c-hci/hci.h  |  2 ++
 3 files changed, 15 insertions(+), 14 deletions(-)

diff --git a/drivers/i3c/master/mipi-i3c-hci/core.c b/drivers/i3c/master/mipi-i3c-hci/core.c
index e80aa1f5722e..4e17b1480362 100644
--- a/drivers/i3c/master/mipi-i3c-hci/core.c
+++ b/drivers/i3c/master/mipi-i3c-hci/core.c
@@ -15,6 +15,7 @@
 #include <linux/interrupt.h>
 #include <linux/iopoll.h>
 #include <linux/module.h>
+#include <linux/pci.h>
 #include <linux/platform_data/mipi-i3c-hci.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
@@ -117,6 +118,17 @@ static inline struct i3c_hci *to_i3c_hci(struct i3c_master_controller *m)
 	return container_of(m, struct i3c_hci, master);
 }
 
+/*
+ * Determine the device that does PM / DMA and has IOMMU setup done for it in
+ * case of enabled IOMMU (for use with the DMA API).
+ * Such device is either "mipi-i3c-hci" platform device (OF/ACPI enumeration)
+ * parent or grandparent (PCI enumeration).
+ */
+struct device *i3c_hci_sysdev(struct device *dev)
+{
+	return dev->parent && dev_is_pci(dev->parent) ? dev->parent : dev;
+}
+
 static void i3c_hci_set_master_dyn_addr(struct i3c_hci *hci)
 {
 	reg_write(MASTER_DEVICE_ADDR,
diff --git a/drivers/i3c/master/mipi-i3c-hci/dma.c b/drivers/i3c/master/mipi-i3c-hci/dma.c
index 0672ed1132f8..7c2b20474130 100644
--- a/drivers/i3c/master/mipi-i3c-hci/dma.c
+++ b/drivers/i3c/master/mipi-i3c-hci/dma.c
@@ -15,7 +15,6 @@
 #include <linux/errno.h>
 #include <linux/i3c/master.h>
 #include <linux/io.h>
-#include <linux/pci.h>
 
 #include "hci.h"
 #include "cmd.h"
@@ -301,23 +300,11 @@ static int hci_dma_init(struct i3c_hci *hci)
 {
 	struct hci_rings_data *rings;
 	struct hci_rh_data *rh;
-	struct device *sysdev;
 	u32 regval;
 	unsigned int i, nr_rings, xfers_sz, resps_sz;
 	unsigned int ibi_status_ring_sz, ibi_data_ring_sz;
 	int ret;
 
-	/*
-	 * Set pointer to a physical device that does DMA and has IOMMU setup
-	 * done for it in case of enabled IOMMU and use it with the DMA API.
-	 * Here such device is either
-	 * "mipi-i3c-hci" platform device (OF/ACPI enumeration) parent or
-	 * grandparent (PCI enumeration).
-	 */
-	sysdev = hci->master.dev.parent;
-	if (sysdev->parent && dev_is_pci(sysdev->parent))
-		sysdev = sysdev->parent;
-
 	regval = rhs_reg_read(CONTROL);
 	nr_rings = FIELD_GET(MAX_HEADER_COUNT_CAP, regval);
 	dev_dbg(&hci->master.dev, "%d DMA rings available\n", nr_rings);
@@ -332,7 +319,7 @@ static int hci_dma_init(struct i3c_hci *hci)
 		return -ENOMEM;
 	hci->io_data = rings;
 	rings->total = nr_rings;
-	rings->sysdev = sysdev;
+	rings->sysdev = i3c_hci_sysdev(hci->master.dev.parent);
 
 	for (i = 0; i < rings->total; i++) {
 		u32 offset = rhs_reg_read(RHn_OFFSET(i));
diff --git a/drivers/i3c/master/mipi-i3c-hci/hci.h b/drivers/i3c/master/mipi-i3c-hci/hci.h
index b3d9803b1968..b8d2a3d680f8 100644
--- a/drivers/i3c/master/mipi-i3c-hci/hci.h
+++ b/drivers/i3c/master/mipi-i3c-hci/hci.h
@@ -184,6 +184,8 @@ void amd_set_resp_buf_thld(struct i3c_hci *hci);
 void i3c_hci_sync_irq_inactive(struct i3c_hci *hci);
 int i3c_hci_process_xfer(struct i3c_hci *hci, struct hci_xfer *xfer, int n);
 
+struct device *i3c_hci_sysdev(struct device *dev);
+
 #define DEFAULT_AUTOSUSPEND_DELAY_MS 1000
 
 int i3c_hci_rpm_suspend(struct device *dev);
-- 
2.53.0