[PATCH 03/15] accel/qda: Add initial QDA DRM accelerator driver

[Ekansh Gupta via B4 Relay]

From: Ekansh Gupta <ekansh.gupta@xxxxxxxxxxxxxxxx>

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@xxxxxxxxxxxxxxxx>
---
 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
+	  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)
+{
+	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");
+}
+
+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;
+
+	ret = qda_register_device(qdev);
+	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);
+}
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