[Linaro-mm-sig] Re: [PATCH 03/15] accel/qda: Add initial QDA DRM accelerator driver

On Tue, May 19, 2026 at 11:45:53AM +0530, Ekansh Gupta via B4 Relay wrote:

From: Ekansh Gupta ekansh.gupta@oss.qualcomm.com

Add the foundational driver files for the Qualcomm DSP Accelerator (QDA), a DRM accel driver for Qualcomm DSPs. The driver integrates with the DRM accel subsystem (drivers/accel/) and provides:

• A standard /dev/accel/accel* character device node via DRM.
• GEM-based buffer management with DMA-BUF import/export (PRIME).
• IOMMU context bank management for per-session memory isolation.
• Standard DRM IOCTLs for device management and job submission.

qda_drv.c / qda_drv.h: Core DRM driver registration. Defines the drm_driver ops table, per-file private state (qda_file_priv), and the main device structure (qda_dev) which embeds drm_device.

qda_rpmsg.c / qda_rpmsg.h: RPMsg transport layer. Registers an rpmsg_driver matching the "qcom,fastrpc" compatible string. On probe it allocates a qda_dev, reads the DSP domain name from the "label" DT property, and registers the DRM device.

Assisted-by: Claude:claude-4-6-sonnet Signed-off-by: Ekansh Gupta ekansh.gupta@oss.qualcomm.com

---

drivers/accel/Kconfig | 1 + drivers/accel/Makefile | 1 + drivers/accel/qda/Kconfig | 30 +++++++++++++ drivers/accel/qda/Makefile | 10 +++++ drivers/accel/qda/qda_drv.c | 97 ++++++++++++++++++++++++++++++++++++++++++ drivers/accel/qda/qda_drv.h | 62 +++++++++++++++++++++++++++ drivers/accel/qda/qda_rpmsg.c | 99 +++++++++++++++++++++++++++++++++++++++++++ drivers/accel/qda/qda_rpmsg.h | 13 ++++++ 8 files changed, 313 insertions(+)

diff --git a/drivers/accel/Kconfig b/drivers/accel/Kconfig index bdf48ccafcf2..74ac0f71bc9d 100644 --- a/drivers/accel/Kconfig +++ b/drivers/accel/Kconfig @@ -29,6 +29,7 @@ source "drivers/accel/ethosu/Kconfig" source "drivers/accel/habanalabs/Kconfig" source "drivers/accel/ivpu/Kconfig" source "drivers/accel/qaic/Kconfig" +source "drivers/accel/qda/Kconfig" source "drivers/accel/rocket/Kconfig" endif diff --git a/drivers/accel/Makefile b/drivers/accel/Makefile index 1d3a7251b950..58c08dd5f389 100644 --- a/drivers/accel/Makefile +++ b/drivers/accel/Makefile @@ -5,4 +5,5 @@ obj-$(CONFIG_DRM_ACCEL_ARM_ETHOSU) += ethosu/ obj-$(CONFIG_DRM_ACCEL_HABANALABS) += habanalabs/ obj-$(CONFIG_DRM_ACCEL_IVPU) += ivpu/ obj-$(CONFIG_DRM_ACCEL_QAIC) += qaic/ +obj-$(CONFIG_DRM_ACCEL_QDA) += qda/ obj-$(CONFIG_DRM_ACCEL_ROCKET) += rocket/ \ No newline at end of file diff --git a/drivers/accel/qda/Kconfig b/drivers/accel/qda/Kconfig new file mode 100644 index 000000000000..484d21ff1b55 --- /dev/null +++ b/drivers/accel/qda/Kconfig @@ -0,0 +1,30 @@ +# SPDX-License-Identifier: GPL-2.0-only +# +# Qualcomm DSP accelerator driver +#

+config DRM_ACCEL_QDA

• tristate "Qualcomm DSP accelerator"
• depends on DRM_ACCEL
• depends on ARCH_QCOM || COMPILE_TEST
• depends on RPMSG
• help

•  Enables the DRM-based accelerator driver for Qualcomm's Hexagon DSPs.
  

•  This driver provides a standardized interface for offloading computational
  

•  tasks to the DSP, including audio processing, sensor offload, computer
  

•  vision, and AI inference workloads.
  

•  The driver supports all DSP domains (ADSP, CDSP, SDSP, GDSP) and
  

•  implements the FastRPC protocol for communication between the application
  

•  processor and DSP. It integrates with the Linux kernel's Compute
  

•  Accelerators subsystem (drivers/accel/) and provides a modern alternative
  

•  to the legacy FastRPC driver found in drivers/misc/.
  

•  Key features include DMA-BUF interoperability for seamless buffer sharing
  

Key features of what? Consider distro maintainers reading your help text in order to identify whether to enable it or not.

•  with other multimedia subsystems, IOMMU-based memory isolation, and
  

•  standard DRM IOCTLs for device management and job submission.
  

•  If unsure, say N.
  

•  To compile this driver as a module, choose M here: the
  

•  module will be called qda.
  

diff --git a/drivers/accel/qda/Makefile b/drivers/accel/qda/Makefile new file mode 100644 index 000000000000..dbe809067a8b --- /dev/null +++ b/drivers/accel/qda/Makefile @@ -0,0 +1,10 @@ +# SPDX-License-Identifier: GPL-2.0-only +# +# Makefile for Qualcomm DSP accelerator driver +#

+obj-$(CONFIG_DRM_ACCEL_QDA) := qda.o

+qda-y := \

• qda_drv.o \
• qda_rpmsg.o

diff --git a/drivers/accel/qda/qda_drv.c b/drivers/accel/qda/qda_drv.c new file mode 100644 index 000000000000..1c1bab68d445 --- /dev/null +++ b/drivers/accel/qda/qda_drv.c @@ -0,0 +1,97 @@ +// SPDX-License-Identifier: GPL-2.0-only +// Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries. +#include <linux/module.h> +#include <linux/slab.h> +#include <drm/drm_accel.h> +#include <drm/drm_drv.h> +#include <drm/drm_file.h> +#include <drm/drm_gem.h> +#include <drm/drm_ioctl.h> +#include <drm/drm_print.h>

+#include "qda_drv.h" +#include "qda_rpmsg.h"

+static int qda_open(struct drm_device *dev, struct drm_file *file) +{

• struct qda_file_priv *qda_file_priv;
• qda_file_priv = kzalloc_obj(*qda_file_priv);
• if (!qda_file_priv)

• return -ENOMEM;
  

• qda_file_priv->qda_dev = qda_dev_from_drm(dev);
• file->driver_priv = qda_file_priv;
• return 0;

+}

+static void qda_postclose(struct drm_device *dev, struct drm_file *file) +{

• struct qda_file_priv *qda_file_priv = file->driver_priv;
• kfree(qda_file_priv);
• file->driver_priv = NULL;

+}

+DEFINE_DRM_ACCEL_FOPS(qda_accel_fops);

+static const struct drm_driver qda_drm_driver = {

• .driver_features = DRIVER_COMPUTE_ACCEL,
• .fops = &qda_accel_fops,
• .open = qda_open,
• .postclose = qda_postclose,
• .name = QDA_DRIVER_NAME,
• .desc = "Qualcomm DSP Accelerator Driver",

+};

+struct qda_dev *qda_alloc_device(struct device *dev) +{

• struct qda_dev *qdev;
• qdev = devm_drm_dev_alloc(dev, &qda_drm_driver, struct qda_dev, drm_dev);
• if (IS_ERR(qdev))

• return ERR_CAST(qdev);
  

• return qdev;

+}

+void qda_unregister_device(struct qda_dev *qdev) +{

• drm_dev_unregister(&qdev->drm_dev);

+}

+int qda_register_device(struct qda_dev *qdev) +{

• int ret;
• ret = drm_dev_register(&qdev->drm_dev, 0);
• if (ret)

• drm_err(&qdev->drm_dev, "Failed to register DRM device: %d\n", ret);
  

• return ret;

+}

+static int __init qda_core_init(void) +{

• int ret;
• ret = qda_rpmsg_register();
• if (ret)

• return ret;
  

• pr_info("qda: QDA driver initialization complete\n");
• return 0;

+}

+static void __exit qda_core_exit(void) +{

• qda_rpmsg_unregister();

+}

+module_init(qda_core_init); +module_exit(qda_core_exit);

+MODULE_AUTHOR("Qualcomm AI Infra Team"); +MODULE_DESCRIPTION("Qualcomm DSP Accelerator Driver"); +MODULE_LICENSE("GPL"); diff --git a/drivers/accel/qda/qda_drv.h b/drivers/accel/qda/qda_drv.h new file mode 100644 index 000000000000..7ba2ef19a411 --- /dev/null +++ b/drivers/accel/qda/qda_drv.h @@ -0,0 +1,62 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/*

• • Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
• */

+#ifndef __QDA_DRV_H__ +#define __QDA_DRV_H__

+#include <linux/device.h> +#include <linux/rpmsg.h> +#include <linux/types.h> +#include <drm/drm_device.h> +#include <drm/drm_drv.h> +#include <drm/drm_file.h>

+/* Driver identification */ +#define QDA_DRIVER_NAME "qda"

+/**

• • struct qda_file_priv - Per-process private data for DRM file
• */

+struct qda_file_priv {

• /** @qda_dev: Back-pointer to device structure */
• struct qda_dev *qda_dev;

+};

+/**

• • struct qda_dev - Main device structure for QDA driver
• • The DRM device is embedded as the first member so that container_of()
• • can recover the qda_dev from any drm_device pointer.
• */

+struct qda_dev {

• /** @drm_dev: Embedded DRM device; recover via qda_dev_from_drm() */
• struct drm_device drm_dev;
• /** @rpdev: RPMsg device for communication with the remote processor */
• struct rpmsg_device *rpdev;
• /** @dev: Underlying Linux device */
• struct device *dev;
• /** @dsp_name: Name of the DSP domain (e.g. "cdsp", "adsp") */
• const char *dsp_name;

+};

+/**

• • qda_dev_from_drm - Recover qda_dev from an embedded drm_device pointer
• • @dev: Pointer to the embedded drm_device
• • Return: Pointer to the enclosing qda_dev.
• */

+static inline struct qda_dev *qda_dev_from_drm(struct drm_device *dev) +{

• return container_of(dev, struct qda_dev, drm_dev);

+}

+/* Device allocation (uses devm_drm_dev_alloc internally) */ +struct qda_dev *qda_alloc_device(struct device *dev);

+/* Core device lifecycle */ +int qda_register_device(struct qda_dev *qdev); +void qda_unregister_device(struct qda_dev *qdev);

+#endif /* __QDA_DRV_H__ */ diff --git a/drivers/accel/qda/qda_rpmsg.c b/drivers/accel/qda/qda_rpmsg.c new file mode 100644 index 000000000000..6eaf1b145f8a --- /dev/null +++ b/drivers/accel/qda/qda_rpmsg.c @@ -0,0 +1,99 @@ +// SPDX-License-Identifier: GPL-2.0-only +// Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries. +#include <linux/module.h> +#include <linux/of.h> +#include <linux/rpmsg.h> +#include <drm/drm_print.h>

+#include "qda_drv.h" +#include "qda_rpmsg.h"

+static struct qda_dev *alloc_and_init_qdev(struct rpmsg_device *rpdev)

Use the prefix uniformly.

+{

• struct qda_dev *qdev;
• qdev = qda_alloc_device(&rpdev->dev);
• if (IS_ERR(qdev))

• return qdev;
  

• qdev->dev = &rpdev->dev;
• qdev->rpdev = rpdev;
• dev_set_drvdata(&rpdev->dev, qdev);
• return qdev;

+}

+static int qda_rpmsg_cb(struct rpmsg_device *rpdev, void *data, int len,

• 	void *priv, u32 src)
  

+{

• /* Placeholder: responses will be dispatched here */
• return 0;

+}

+static void qda_rpmsg_remove(struct rpmsg_device *rpdev) +{

• struct qda_dev *qdev = dev_get_drvdata(&rpdev->dev);
• drm_dev_unplug(&qdev->drm_dev);
• qdev->rpdev = NULL;
• qda_unregister_device(qdev);
• dev_info(qdev->dev, "RPMsg device removed\n");

Drop the spamming. And useless (where it is useless) drm_dbg() / dev_dbg() spamming too.

+}

+static int qda_rpmsg_probe(struct rpmsg_device *rpdev) +{

• struct qda_dev *qdev;
• const char *label;
• int ret;
• dev_dbg(&rpdev->dev, "QDA RPMsg probe starting\n");
• qdev = alloc_and_init_qdev(rpdev);
• if (IS_ERR(qdev))

• return PTR_ERR(qdev);
  

• ret = of_property_read_string(rpdev->dev.of_node, "label", &label);
• if (ret) {

• dev_err(qdev->dev, "Missing 'label' property in DT node: %d\n", ret);
  

• return ret;
  

• }
• qdev->dsp_name = label;

Why not just of_property_read_string(...., &qdev->dsp_name)?

• ret = qda_register_device(qdev);

return qda_register_device();

• if (ret)

• return ret;
  

• drm_info(&qdev->drm_dev, "QDA RPMsg probe complete for %s\n", qdev->dsp_name);
• return 0;

+}

+static const struct of_device_id qda_rpmsg_id_table[] = {

• { .compatible = "qcom,fastrpc" },
• {},

+}; +MODULE_DEVICE_TABLE(of, qda_rpmsg_id_table);

+static struct rpmsg_driver qda_rpmsg_driver = {

• .probe = qda_rpmsg_probe,
• .remove = qda_rpmsg_remove,
• .callback = qda_rpmsg_cb,
• .drv = {

• .name = "qcom,fastrpc",
  

• .of_match_table = qda_rpmsg_id_table,
  

• },

+};

+int qda_rpmsg_register(void) +{

• int ret = register_rpmsg_driver(&qda_rpmsg_driver);
• if (ret)

• pr_err("qda: Failed to register RPMsg driver: %d\n", ret);
  

• return ret;

+}

+void qda_rpmsg_unregister(void) +{

• unregister_rpmsg_driver(&qda_rpmsg_driver);

+}

Just use module_rpmsg_driver(), drop all the wrappers and module_init() / exit().

diff --git a/drivers/accel/qda/qda_rpmsg.h b/drivers/accel/qda/qda_rpmsg.h new file mode 100644 index 000000000000..5229d834b34b --- /dev/null +++ b/drivers/accel/qda/qda_rpmsg.h @@ -0,0 +1,13 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/*

• • Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
• */

+#ifndef __QDA_RPMSG_H__ +#define __QDA_RPMSG_H__

+/* RPMsg transport layer registration */ +int qda_rpmsg_register(void); +void qda_rpmsg_unregister(void);

+#endif /* __QDA_RPMSG_H__ */

-- 2.34.1