Allow user-space to import DMA-BUF file descriptors from other
subsystems (GPU, camera, video) into the QDA driver via the standard
DRM PRIME interface.
qda_prime.c
Implements qda_gem_prime_import(), which is set as the driver's
.gem_prime_import callback. On import it:
1. Short-circuits self-import: if the dma_buf was exported by this
device and is not itself an import, the existing GEM object is
returned with an incremented reference count.
2. Attaches to the dma_buf and maps it with DMA_BIDIRECTIONAL via
dma_buf_map_attachment_unlocked(), obtaining an sg_table whose
DMA addresses are IOMMU virtual addresses in the CB device's
address space.
3. Calls qda_memory_manager_alloc() to record the mapping and encode
the SID in the upper bits of the DMA address, matching the
convention used for natively allocated buffers.
qda_prime_fd_to_handle() wraps drm_gem_prime_fd_to_handle() under
qdev->import_lock, storing the calling file_priv in
qdev->current_import_file_priv so that qda_gem_prime_import() can
retrieve it (the .gem_prime_import callback does not receive
file_priv directly, but the context bank to attach to is per-process).
qda_gem.c
qda_gem_free_object() is extended to handle the imported-buffer
teardown path: unmap the sg_table, detach from the dma_buf, and
release the dma_buf reference.
qda_gem_mmap_obj() rejects mmap requests on imported objects, which
must be mapped through the exporter instead.
qda_memory_manager.c
The DSP is given a single base address per buffer, so only buffers
that are mapped as one contiguous range can be described to it.
qda_memory_manager_map_imported() therefore walks the imported
buffer's scatterlist and rejects any buffer whose entries are not
contiguous; contiguous imports (for example from the CMA DMA-buf
heap) are accepted. Whether an exporter or IOMMU coalesces a buffer
into a single range is not guaranteed, so this is verified rather
than assumed.
qda_memory_manager_free() skips the DMA free path for imported
buffers since the memory is owned by the exporter.
Assisted-by: Claude:claude-sonnet-5
Signed-off-by: Ekansh Gupta <[email protected]>
---
Changes in v2:
- Do not assume the exporter or IOMMU maps an imported buffer as a
single contiguous range; walk the scatterlist and cleanly reject
non-contiguous imports instead (Christian König)
- Document that only contiguous imports (e.g. CMA DMA-buf heap) are
supported
- Return -EBUSY rather than -ENODEV when no context bank is available
---
drivers/accel/qda/Makefile | 1 +
drivers/accel/qda/qda_drv.c | 12 ++-
drivers/accel/qda/qda_drv.h | 4 +
drivers/accel/qda/qda_gem.c | 25 ++++-
drivers/accel/qda/qda_gem.h | 8 ++
drivers/accel/qda/qda_memory_manager.c | 42 +++++++++
drivers/accel/qda/qda_prime.c | 167 +++++++++++++++++++++++++++++++++
drivers/accel/qda/qda_prime.h | 18 ++++
8 files changed, 274 insertions(+), 3 deletions(-)
diff --git a/drivers/accel/qda/Makefile b/drivers/accel/qda/Makefile
index a46ddceecfc5..fb092e56d7f3 100644
--- a/drivers/accel/qda/Makefile
+++ b/drivers/accel/qda/Makefile
@@ -12,6 +12,7 @@ qda-y := \
qda_ioctl.o \
qda_memory_dma.o \
qda_memory_manager.o \
+ qda_prime.o \
qda_rpmsg.o
obj-$(CONFIG_DRM_ACCEL_QDA_COMPUTE_BUS) += qda_compute_bus.o
diff --git a/drivers/accel/qda/qda_drv.c b/drivers/accel/qda/qda_drv.c
index d22c2c66ffc4..a68a07d0ae56 100644
--- a/drivers/accel/qda/qda_drv.c
+++ b/drivers/accel/qda/qda_drv.c
@@ -7,11 +7,13 @@
#include <drm/drm_file.h>
#include <drm/drm_gem.h>
#include <drm/drm_ioctl.h>
+#include <drm/drm_prime.h>
#include <drm/drm_print.h>
#include <drm/qda_accel.h>
#include "qda_drv.h"
#include "qda_ioctl.h"
+#include "qda_prime.h"
static int qda_open(struct drm_device *dev, struct drm_file *file)
{
@@ -54,6 +56,8 @@ static const struct drm_driver qda_drm_driver = {
.postclose = qda_postclose,
.ioctls = qda_ioctls,
.num_ioctls = ARRAY_SIZE(qda_ioctls),
+ .gem_prime_import = qda_gem_prime_import,
+ .prime_fd_to_handle = qda_prime_fd_to_handle,
.name = QDA_DRIVER_NAME,
.desc = "Qualcomm DSP Accelerator Driver",
};
@@ -72,6 +76,7 @@ struct qda_dev *qda_alloc_device(struct device *dev)
void qda_deinit_device(struct qda_dev *qdev)
{
+ mutex_destroy(&qdev->import_lock);
if (qdev->iommu_mgr) {
qda_memory_manager_exit(qdev->iommu_mgr);
kfree(qdev->iommu_mgr);
@@ -83,14 +88,19 @@ int qda_init_device(struct qda_dev *qdev, int num_cbs)
{
int ret;
+ mutex_init(&qdev->import_lock);
+ qdev->current_import_file_priv = NULL;
qdev->iommu_mgr = kzalloc_obj(*qdev->iommu_mgr);
- if (!qdev->iommu_mgr)
+ if (!qdev->iommu_mgr) {
+ mutex_destroy(&qdev->import_lock);
return -ENOMEM;
+ }
ret = qda_memory_manager_init(qdev->iommu_mgr, num_cbs);
if (ret) {
drm_err(&qdev->drm_dev, "Failed to initialize memory manager:
%d\n", ret);
kfree(qdev->iommu_mgr);
qdev->iommu_mgr = NULL;
+ mutex_destroy(&qdev->import_lock);
}
return ret;
diff --git a/drivers/accel/qda/qda_drv.h b/drivers/accel/qda/qda_drv.h
index 2fe58f3efec0..422e70b971b8 100644
--- a/drivers/accel/qda/qda_drv.h
+++ b/drivers/accel/qda/qda_drv.h
@@ -47,6 +47,10 @@ struct qda_dev {
struct list_head cb_devs;
/** @iommu_mgr: IOMMU/memory manager instance */
struct qda_memory_manager *iommu_mgr;
+ /** @import_lock: Lock protecting prime import context */
+ struct mutex import_lock;
+ /** @current_import_file_priv: Current file_priv during prime import */
+ struct drm_file *current_import_file_priv;
/** @dsp_name: Name of the DSP domain (e.g. "cdsp", "adsp") */
const char *dsp_name;
};
diff --git a/drivers/accel/qda/qda_gem.c b/drivers/accel/qda/qda_gem.c
index 66e78013a726..6f5c54daa951 100644
--- a/drivers/accel/qda/qda_gem.c
+++ b/drivers/accel/qda/qda_gem.c
@@ -9,6 +9,7 @@
#include "qda_gem.h"
#include "qda_memory_manager.h"
#include "qda_memory_dma.h"
+#include "qda_prime.h"
/**
* qda_gem_free_object() - Free a GEM object and its associated resources
@@ -19,8 +20,20 @@ void qda_gem_free_object(struct drm_gem_object *gem_obj)
struct qda_gem_obj *qda_gem_obj = to_qda_gem_obj(gem_obj);
struct qda_dev *qdev = qda_dev_from_drm(gem_obj->dev);
- if (qda_gem_obj->virt && qdev->iommu_mgr)
- qda_memory_manager_free(qdev->iommu_mgr, qda_gem_obj);
+ if (qda_gem_obj->is_imported) {
+ if (qda_gem_obj->attachment && qda_gem_obj->sgt)
+
dma_buf_unmap_attachment_unlocked(qda_gem_obj->attachment,
+ qda_gem_obj->sgt,
DMA_BIDIRECTIONAL);
+ if (qda_gem_obj->attachment)
+ dma_buf_detach(qda_gem_obj->dma_buf,
qda_gem_obj->attachment);
+ if (qda_gem_obj->dma_buf)
+ dma_buf_put(qda_gem_obj->dma_buf);
+ if (qda_gem_obj->iommu_dev && qdev->iommu_mgr)
+ qda_memory_manager_free(qdev->iommu_mgr, qda_gem_obj);
+ } else {
+ if (qda_gem_obj->virt && qdev->iommu_mgr)
+ qda_memory_manager_free(qdev->iommu_mgr, qda_gem_obj);
+ }
drm_gem_object_release(gem_obj);
kfree(qda_gem_obj);
@@ -38,6 +51,10 @@ int qda_gem_mmap_obj(struct drm_gem_object *drm_obj, struct
vm_area_struct *vma)
struct qda_gem_obj *qda_gem_obj = to_qda_gem_obj(drm_obj);
int ret;
+ /* Imported dma-buf objects must be mmap'd through the exporter, not
the importer */
+ if (qda_gem_obj->is_imported)
+ return -EINVAL;
+
/* The fake offset is only used to find the object, not to index it */
vma->vm_pgoff = 0;
@@ -123,6 +140,10 @@ struct drm_gem_object *qda_gem_create_object(struct
drm_device *drm_dev,
qda_gem_obj = qda_gem_alloc_object(drm_dev, aligned_size);
if (IS_ERR(qda_gem_obj))
return ERR_CAST(qda_gem_obj);
+ qda_gem_obj->is_imported = false;
+ qda_gem_obj->dma_buf = NULL;
+ qda_gem_obj->attachment = NULL;
+ qda_gem_obj->sgt = NULL;
ret = qda_memory_manager_alloc(iommu_mgr, qda_gem_obj, file_priv);
if (ret) {
diff --git a/drivers/accel/qda/qda_gem.h b/drivers/accel/qda/qda_gem.h
index afd7c9b49549..3e28d14099fb 100644
--- a/drivers/accel/qda/qda_gem.h
+++ b/drivers/accel/qda/qda_gem.h
@@ -21,12 +21,20 @@ struct qda_gem_obj {
struct drm_gem_object base;
/** @iommu_dev: IOMMU context bank device that performed the allocation
*/
struct qda_iommu_device *iommu_dev;
+ /** @dma_buf: Reference to imported dma_buf */
+ struct dma_buf *dma_buf;
+ /** @attachment: DMA buf attachment */
+ struct dma_buf_attachment *attachment;
+ /** @sgt: Scatter-gather table */
+ struct sg_table *sgt;
/** @virt: Kernel virtual address of the allocated DMA memory */
void *virt;
/** @dma_addr: DMA address (with SID encoded in upper 32 bits) */
dma_addr_t dma_addr;
/** @size: Size of the buffer in bytes */
size_t size;
+ /** @is_imported: True if buffer is imported, false if allocated */
+ bool is_imported;
};
/**
diff --git a/drivers/accel/qda/qda_memory_manager.c
b/drivers/accel/qda/qda_memory_manager.c
index d47c7419e11d..3c25ec47cd09 100644
--- a/drivers/accel/qda/qda_memory_manager.c
+++ b/drivers/accel/qda/qda_memory_manager.c
@@ -209,6 +209,41 @@ static struct qda_iommu_device
*get_or_assign_iommu_device(struct qda_memory_man
return NULL;
}
+static int qda_memory_manager_map_imported(struct qda_gem_obj *gem_obj,
+ struct qda_iommu_device *iommu_dev)
+{
+ dma_addr_t dma_addr, expected_addr = 0;
+ struct scatterlist *sg, *s;
+ int i;
+
+ sg = gem_obj->sgt->sgl;
+
+ /*
+ * Verify that the imported DMA-BUF is contiguous. While some platforms
+ * or IOMMUs might map buffers as a single range, we must not silently
+ * assume this is always the case. We loop through the scatterlist
+ * entries and reject any that are non-contiguous.
+ */
+ for_each_sg(gem_obj->sgt->sgl, s, gem_obj->sgt->nents, i) {
+ dma_addr_t curr_addr = sg_dma_address(s);
+
+ if (i > 0 && curr_addr != expected_addr) {
+ drm_err_ratelimited(gem_obj->base.dev,
+ "Imported DMA-BUF is
non-contiguous; rejecting mapping\n");
+ return -EINVAL;
+ }
+ expected_addr = curr_addr + sg_dma_len(s);
+ }
+
+ gem_obj->iommu_dev = iommu_dev;
+
+ dma_addr = sg_dma_address(sg);
+ dma_addr += ((u64)iommu_dev->sid << 32);
+ gem_obj->dma_addr = dma_addr;
+
+ return 0;
+}
+
/**
* qda_memory_manager_alloc() - Allocate memory for a GEM object
* @mem_mgr: Pointer to memory manager
@@ -226,6 +261,9 @@ int qda_memory_manager_alloc(struct qda_memory_manager
*mem_mgr, struct qda_gem_
if (!selected_dev)
return -EBUSY;
+ if (gem_obj->is_imported)
+ return qda_memory_manager_map_imported(gem_obj, selected_dev);
+
return qda_dma_alloc(selected_dev, gem_obj, gem_obj->size);
}
@@ -236,6 +274,10 @@ int qda_memory_manager_alloc(struct qda_memory_manager
*mem_mgr, struct qda_gem_
*/
void qda_memory_manager_free(struct qda_memory_manager *mem_mgr, struct
qda_gem_obj *gem_obj)
{
+ /* Imported buffers are unmapped through the exporter, not here */
+ if (gem_obj->is_imported)
+ return;
+
qda_dma_free(gem_obj);
}
diff --git a/drivers/accel/qda/qda_prime.c b/drivers/accel/qda/qda_prime.c
new file mode 100644
index 000000000000..306b3037c19c
--- /dev/null
+++ b/drivers/accel/qda/qda_prime.c
@@ -0,0 +1,167 @@
+// SPDX-License-Identifier: GPL-2.0-only
+// Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
+#include <drm/drm_gem.h>
+#include <drm/drm_prime.h>
+#include <drm/drm_print.h>
+#include <linux/slab.h>
+#include <linux/dma-mapping.h>
+#include "qda_drv.h"
+#include "qda_gem.h"
+#include "qda_prime.h"
+#include "qda_memory_manager.h"
+
+static struct drm_gem_object *check_own_buffer(struct drm_device *dev, struct
dma_buf *dma_buf)
+{
+ struct drm_gem_object *existing_gem;
+
+ /* Only safe to access priv if this dma-buf was exported by this device
*/
+ if (!drm_gem_is_prime_exported_dma_buf(dev, dma_buf))
+ return NULL;
+
+ existing_gem = dma_buf->priv;
+ if (existing_gem->dev != dev)
+ return NULL;
+
+ if (to_qda_gem_obj(existing_gem)->is_imported)
+ return NULL;
+
+ drm_gem_object_get(existing_gem);
+ return existing_gem;
+}
+
+static struct qda_iommu_device *get_iommu_device_for_import(struct qda_dev
*qdev,
+ struct drm_file
**file_priv_out)
+{
+ struct drm_file *file_priv;
+ struct qda_file_priv *qda_file_priv;
+ struct qda_iommu_device *iommu_dev;
+
+ file_priv = qdev->current_import_file_priv;
+ *file_priv_out = file_priv;
+
+ if (!file_priv || !file_priv->driver_priv)
+ return NULL;
+
+ qda_file_priv = (struct qda_file_priv *)file_priv->driver_priv;
+ iommu_dev = qda_file_priv->assigned_iommu_dev;
+
+ if (!iommu_dev) {
+ if (qda_memory_manager_assign_device(qdev->iommu_mgr,
file_priv))
+ return NULL;
+
+ iommu_dev = qda_file_priv->assigned_iommu_dev;
+ }
+
+ return iommu_dev;
+}
+
+static int setup_dma_buf_mapping(struct qda_gem_obj *qda_gem_obj, struct
dma_buf *dma_buf,
+ struct device *attach_dev)
+{
+ struct dma_buf_attachment *attachment;
+ struct sg_table *sgt;
+ int ret;
+
+ attachment = dma_buf_attach(dma_buf, attach_dev);
+ if (IS_ERR(attachment))
+ return PTR_ERR(attachment);
+
+ qda_gem_obj->attachment = attachment;
+
+ sgt = dma_buf_map_attachment_unlocked(attachment, DMA_BIDIRECTIONAL);
+ if (IS_ERR(sgt)) {
+ ret = PTR_ERR(sgt);
+ dma_buf_detach(dma_buf, attachment);
+ return ret;
+ }
+ qda_gem_obj->sgt = sgt;
+
+ return 0;
+}
+
+/**
+ * qda_gem_prime_import() - Import a DMA-BUF as a GEM object
+ * @dev: DRM device structure
+ * @dma_buf: DMA-BUF to import
+ *
+ * Return: Pointer to the imported GEM object on success, ERR_PTR on failure
+ */
+struct drm_gem_object *qda_gem_prime_import(struct drm_device *dev, struct
dma_buf *dma_buf)
+{
+ struct qda_dev *qdev = qda_dev_from_drm(dev);
+ struct qda_gem_obj *qda_gem_obj;
+ struct drm_file *file_priv;
+ struct qda_iommu_device *iommu_dev;
+ struct drm_gem_object *existing_gem;
+ size_t aligned_size;
+ int ret;
+
+ existing_gem = check_own_buffer(dev, dma_buf);
+ if (existing_gem)
+ return existing_gem;
+
+ iommu_dev = get_iommu_device_for_import(qdev, &file_priv);
+ if (!iommu_dev || !iommu_dev->dev) {
+ drm_dbg_driver(dev, "No context bank available for prime
import\n");
+ return ERR_PTR(-EBUSY);
+ }
+
+ aligned_size = PAGE_ALIGN(dma_buf->size);
+ qda_gem_obj = qda_gem_alloc_object(dev, aligned_size);
+ if (IS_ERR(qda_gem_obj))
+ return ERR_CAST(qda_gem_obj);
+
+ qda_gem_obj->is_imported = true;
+ qda_gem_obj->dma_buf = dma_buf;
+ qda_gem_obj->virt = NULL;
+ qda_gem_obj->iommu_dev = iommu_dev;
+
+ get_dma_buf(dma_buf);
+
+ ret = setup_dma_buf_mapping(qda_gem_obj, dma_buf, iommu_dev->dev);
+ if (ret)
+ goto err_put_dma_buf;
+
+ ret = qda_memory_manager_alloc(qdev->iommu_mgr, qda_gem_obj, file_priv);
+ if (ret)
+ goto err_unmap;
+
+ return &qda_gem_obj->base;
+
+err_unmap:
+ dma_buf_unmap_attachment_unlocked(qda_gem_obj->attachment,
+ qda_gem_obj->sgt, DMA_BIDIRECTIONAL);
+ dma_buf_detach(dma_buf, qda_gem_obj->attachment);
+err_put_dma_buf:
+ dma_buf_put(dma_buf);
+ qda_gem_cleanup_object(qda_gem_obj);
+ return ERR_PTR(ret);
+}
+
+/**
+ * qda_prime_fd_to_handle() - Convert a PRIME fd to a GEM handle
+ * @dev: DRM device structure
+ * @file_priv: DRM file private data
+ * @prime_fd: File descriptor of the PRIME buffer
+ * @handle: Output GEM handle
+ *
+ * Return: 0 on success, negative error code on failure
+ */
+int qda_prime_fd_to_handle(struct drm_device *dev, struct drm_file *file_priv,
+ int prime_fd, u32 *handle)
+{
+ struct qda_dev *qdev = qda_dev_from_drm(dev);
+ int ret;
+
+ mutex_lock(&qdev->import_lock);
+ qdev->current_import_file_priv = file_priv;
+
+ ret = drm_gem_prime_fd_to_handle(dev, file_priv, prime_fd, handle);
+
+ qdev->current_import_file_priv = NULL;
+ mutex_unlock(&qdev->import_lock);
+
+ return ret;
+}
+
+MODULE_IMPORT_NS("DMA_BUF");
diff --git a/drivers/accel/qda/qda_prime.h b/drivers/accel/qda/qda_prime.h
new file mode 100644
index 000000000000..9b3850d54fa7
--- /dev/null
+++ b/drivers/accel/qda/qda_prime.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
+ */
+
+#ifndef __QDA_PRIME_H__
+#define __QDA_PRIME_H__
+
+#include <drm/drm_device.h>
+#include <drm/drm_file.h>
+#include <drm/drm_gem.h>
+#include <linux/dma-buf.h>
+
+struct drm_gem_object *qda_gem_prime_import(struct drm_device *dev, struct
dma_buf *dma_buf);
+int qda_prime_fd_to_handle(struct drm_device *dev, struct drm_file *file_priv,
+ int prime_fd, u32 *handle);
+
+#endif /* __QDA_PRIME_H__ */
--
2.34.1
