[PATCH 2/3] i3c: mipi-i3c-hci: Use physical device pointer with DMA API

[Jarkko Nikula <jarkko.nikula@linux.intel.com>]

DMA transfer faults on Intel hardware when the IOMMU is enabled and
driver initialization will fail when attempting to do the first transfer:

	DMAR: DRHD: handling fault status reg 2
	DMAR: [DMA Read NO_PASID] Request device [00:11.0] fault addr 0x676e3000 [fault reason 0x71] SM: Present bit in first-level paging entry is clear
	i3c mipi-i3c-hci.0: ring 0: Transfer Aborted
	mipi-i3c-hci mipi-i3c-hci.0: probe with driver mipi-i3c-hci failed with error -62

Reason for this is that the IOMMU setup is done for the physical devices
only and not for the virtual I3C Controller device object.

Therefore use the pointer to a physical device object with the DMA API.

Due to a data corruption observation when the device DMA is IOMMU
mapped, a properly sized receive bounce buffer is required if transfer
length is not a multiple of DWORDs. Extend the check in the
hci_dma_alloc_safe_xfer_buf() when bounce buffer allocation is required
and when it can be skipped.

Reported-by: Prabhakaran, Krishna <krishna.prabhakaran@intel.com>
Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
---
 drivers/i3c/master/mipi-i3c-hci/dma.c | 53 +++++++++++++++++++--------
 1 file changed, 38 insertions(+), 15 deletions(-)

diff --git a/drivers/i3c/master/mipi-i3c-hci/dma.c b/drivers/i3c/master/mipi-i3c-hci/dma.c
index 0311c84f5b4e..20e1b405244e 100644
--- a/drivers/i3c/master/mipi-i3c-hci/dma.c
+++ b/drivers/i3c/master/mipi-i3c-hci/dma.c
@@ -14,6 +14,7 @@
 #include <linux/errno.h>
 #include <linux/i3c/master.h>
 #include <linux/io.h>
+#include <linux/pci.h>
 
 #include "hci.h"
 #include "cmd.h"
@@ -138,6 +139,7 @@ struct hci_rh_data {
 };
 
 struct hci_rings_data {
+	struct device *sysdev;
 	unsigned int total;
 	struct hci_rh_data headers[] __counted_by(total);
 };
@@ -165,20 +167,20 @@ static void hci_dma_cleanup(struct i3c_hci *hci)
 		rh_reg_write(IBI_SETUP, 0);
 
 		if (rh->xfer)
-			dma_free_coherent(&hci->master.dev,
+			dma_free_coherent(rings->sysdev,
 					  rh->xfer_struct_sz * rh->xfer_entries,
 					  rh->xfer, rh->xfer_dma);
 		if (rh->resp)
-			dma_free_coherent(&hci->master.dev,
+			dma_free_coherent(rings->sysdev,
 					  rh->resp_struct_sz * rh->xfer_entries,
 					  rh->resp, rh->resp_dma);
 		kfree(rh->src_xfers);
 		if (rh->ibi_status)
-			dma_free_coherent(&hci->master.dev,
+			dma_free_coherent(rings->sysdev,
 					  rh->ibi_status_sz * rh->ibi_status_entries,
 					  rh->ibi_status, rh->ibi_status_dma);
 		if (rh->ibi_data_dma)
-			dma_unmap_single(&hci->master.dev, rh->ibi_data_dma,
+			dma_unmap_single(rings->sysdev, rh->ibi_data_dma,
 					 rh->ibi_chunk_sz * rh->ibi_chunks_total,
 					 DMA_FROM_DEVICE);
 		kfree(rh->ibi_data);
@@ -194,11 +196,23 @@ 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_info(&hci->master.dev, "%d DMA rings available\n", nr_rings);
@@ -213,6 +227,7 @@ static int hci_dma_init(struct i3c_hci *hci)
 		return -ENOMEM;
 	hci->io_data = rings;
 	rings->total = nr_rings;
+	rings->sysdev = sysdev;
 
 	regval = FIELD_PREP(MAX_HEADER_COUNT, rings->total);
 	rhs_reg_write(CONTROL, regval);
@@ -239,9 +254,9 @@ static int hci_dma_init(struct i3c_hci *hci)
 		xfers_sz = rh->xfer_struct_sz * rh->xfer_entries;
 		resps_sz = rh->resp_struct_sz * rh->xfer_entries;
 
-		rh->xfer = dma_alloc_coherent(&hci->master.dev, xfers_sz,
+		rh->xfer = dma_alloc_coherent(rings->sysdev, xfers_sz,
 					      &rh->xfer_dma, GFP_KERNEL);
-		rh->resp = dma_alloc_coherent(&hci->master.dev, resps_sz,
+		rh->resp = dma_alloc_coherent(rings->sysdev, resps_sz,
 					      &rh->resp_dma, GFP_KERNEL);
 		rh->src_xfers =
 			kmalloc_array(rh->xfer_entries, sizeof(*rh->src_xfers),
@@ -295,16 +310,16 @@ static int hci_dma_init(struct i3c_hci *hci)
 		ibi_data_ring_sz = rh->ibi_chunk_sz * rh->ibi_chunks_total;
 
 		rh->ibi_status =
-			dma_alloc_coherent(&hci->master.dev, ibi_status_ring_sz,
+			dma_alloc_coherent(rings->sysdev, ibi_status_ring_sz,
 					   &rh->ibi_status_dma, GFP_KERNEL);
 		rh->ibi_data = kmalloc(ibi_data_ring_sz, GFP_KERNEL);
 		ret = -ENOMEM;
 		if (!rh->ibi_status || !rh->ibi_data)
 			goto err_out;
 		rh->ibi_data_dma =
-			dma_map_single(&hci->master.dev, rh->ibi_data,
+			dma_map_single(rings->sysdev, rh->ibi_data,
 				       ibi_data_ring_sz, DMA_FROM_DEVICE);
-		if (dma_mapping_error(&hci->master.dev, rh->ibi_data_dma)) {
+		if (dma_mapping_error(rings->sysdev, rh->ibi_data_dma)) {
 			rh->ibi_data_dma = 0;
 			ret = -ENOMEM;
 			goto err_out;
@@ -342,7 +357,13 @@ static int hci_dma_init(struct i3c_hci *hci)
 static void *hci_dma_alloc_safe_xfer_buf(struct i3c_hci *hci,
 					 struct hci_xfer *xfer)
 {
-	if (!is_vmalloc_addr(xfer->data))
+	struct hci_rings_data *rings = hci->io_data;
+
+	if (!is_vmalloc_addr(xfer->data) &&
+	    (!device_iommu_mapped(rings->sysdev) ||
+	     !xfer->rnw ||
+	     xfer->data_len == ALIGN(xfer->data_len, 4)))
+		/* Bounce buffer not required for this transfer */
 		return xfer->data;
 
 	if (xfer->rnw)
@@ -380,6 +401,7 @@ static void hci_dma_free_safe_xfer_buf(struct i3c_hci *hci,
 static void hci_dma_unmap_xfer(struct i3c_hci *hci,
 			       struct hci_xfer *xfer_list, unsigned int n)
 {
+	struct hci_rings_data *rings = hci->io_data;
 	struct hci_xfer *xfer;
 	unsigned int i;
 
@@ -387,7 +409,7 @@ static void hci_dma_unmap_xfer(struct i3c_hci *hci,
 		xfer = xfer_list + i;
 		if (!xfer->data)
 			continue;
-		dma_unmap_single(&hci->master.dev,
+		dma_unmap_single(rings->sysdev,
 				 xfer->data_dma, xfer->data_len,
 				 xfer->rnw ? DMA_FROM_DEVICE : DMA_TO_DEVICE);
 		hci_dma_free_safe_xfer_buf(hci, xfer);
@@ -437,13 +459,13 @@ static int hci_dma_queue_xfer(struct i3c_hci *hci,
 			}
 
 			xfer->data_dma =
-				dma_map_single(&hci->master.dev,
+				dma_map_single(rings->sysdev,
 					       buf,
 					       xfer->data_len,
 					       xfer->rnw ?
 						  DMA_FROM_DEVICE :
 						  DMA_TO_DEVICE);
-			if (dma_mapping_error(&hci->master.dev,
+			if (dma_mapping_error(rings->sysdev,
 					      xfer->data_dma)) {
 				hci_dma_free_safe_xfer_buf(hci, xfer);
 				hci_dma_unmap_xfer(hci, xfer_list, i);
@@ -631,6 +653,7 @@ static void hci_dma_recycle_ibi_slot(struct i3c_hci *hci,
 
 static void hci_dma_process_ibi(struct i3c_hci *hci, struct hci_rh_data *rh)
 {
+	struct hci_rings_data *rings = hci->io_data;
 	struct i3c_dev_desc *dev;
 	struct i3c_hci_dev_data *dev_data;
 	struct hci_dma_dev_ibi_data *dev_ibi;
@@ -741,7 +764,7 @@ static void hci_dma_process_ibi(struct i3c_hci *hci, struct hci_rh_data *rh)
 			* rh->ibi_chunk_sz;
 	if (first_part > ibi_size)
 		first_part = ibi_size;
-	dma_sync_single_for_cpu(&hci->master.dev, ring_ibi_data_dma,
+	dma_sync_single_for_cpu(rings->sysdev, ring_ibi_data_dma,
 				first_part, DMA_FROM_DEVICE);
 	memcpy(slot->data, ring_ibi_data, first_part);
 
@@ -750,7 +773,7 @@ static void hci_dma_process_ibi(struct i3c_hci *hci, struct hci_rh_data *rh)
 		/* we wrap back to the start and copy remaining data */
 		ring_ibi_data = rh->ibi_data;
 		ring_ibi_data_dma = rh->ibi_data_dma;
-		dma_sync_single_for_cpu(&hci->master.dev, ring_ibi_data_dma,
+		dma_sync_single_for_cpu(rings->sysdev, ring_ibi_data_dma,
 					ibi_size - first_part, DMA_FROM_DEVICE);
 		memcpy(slot->data + first_part, ring_ibi_data,
 		       ibi_size - first_part);
-- 
2.47.2


-- 
linux-i3c mailing list
linux-i3c@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-i3c