[PATCH RFC 09/18] accel/qda: Add QUERY IOCTL and basic QDA UAPI header

[Ekansh Gupta]

Introduce a basic UAPI for the QDA accelerator driver along with a
DRM IOCTL handler to query DSP device identity. A new UAPI header
include/uapi/drm/qda_accel.h defines DRM_QDA_QUERY, the corresponding
DRM_IOCTL_QDA_QUERY command, and struct drm_qda_query, which contains
a DSP name string.

On the kernel side, qda_ioctl_query() validates the per-file context,
resolves the qda_dev instance from dev->dev_private, and copies the
DSP name from qdev->dsp_name into the query structure. The new
qda_ioctls[] table wires this IOCTL into the QDA DRM driver so
userspace can call it through the standard DRM command interface.

This IOCTL provides a simple and stable way for userspace to discover
which DSP a given QDA device node represents and serves as the first
building block for a richer QDA UAPI in subsequent patches.

Signed-off-by: Ekansh Gupta <ekansh.gupta@xxxxxxxxxxxxxxxx>
---
 drivers/accel/qda/Makefile    |  1 +
 drivers/accel/qda/qda_drv.c   |  9 +++++++++
 drivers/accel/qda/qda_ioctl.c | 45 +++++++++++++++++++++++++++++++++++++++++
 drivers/accel/qda/qda_ioctl.h | 26 ++++++++++++++++++++++++
 include/uapi/drm/qda_accel.h  | 47 +++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 128 insertions(+)

diff --git a/drivers/accel/qda/Makefile b/drivers/accel/qda/Makefile
index 7e96ddc40a24..f547398e1a72 100644
--- a/drivers/accel/qda/Makefile
+++ b/drivers/accel/qda/Makefile
@@ -10,5 +10,6 @@ qda-y := \
 	qda_rpmsg.o \
 	qda_cb.o \
 	qda_memory_manager.o \
+	qda_ioctl.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 bf95fc782cf8..86758a9cd982 100644
--- a/drivers/accel/qda/qda_drv.c
+++ b/drivers/accel/qda/qda_drv.c
@@ -9,7 +9,10 @@
 #include <drm/drm_file.h>
 #include <drm/drm_gem.h>
 #include <drm/drm_ioctl.h>
+#include <drm/qda_accel.h>
+
 #include "qda_drv.h"
+#include "qda_ioctl.h"
 #include "qda_rpmsg.h"
 
 static struct qda_drm_priv *get_drm_priv_from_device(struct drm_device *dev)
@@ -128,11 +131,17 @@ static void qda_postclose(struct drm_device *dev, struct drm_file *file)
 
 DEFINE_DRM_ACCEL_FOPS(qda_accel_fops);
 
+static const struct drm_ioctl_desc qda_ioctls[] = {
+	DRM_IOCTL_DEF_DRV(QDA_QUERY, qda_ioctl_query, 0),
+};
+
 static struct drm_driver qda_drm_driver = {
 	.driver_features = DRIVER_COMPUTE_ACCEL,
 	.fops			= &qda_accel_fops,
 	.open			= qda_open,
 	.postclose		= qda_postclose,
+	.ioctls = qda_ioctls,
+	.num_ioctls = ARRAY_SIZE(qda_ioctls),
 	.name = DRIVER_NAME,
 	.desc = "Qualcomm DSP Accelerator Driver",
 };
diff --git a/drivers/accel/qda/qda_ioctl.c b/drivers/accel/qda/qda_ioctl.c
new file mode 100644
index 000000000000..9fa73ec2dfce
--- /dev/null
+++ b/drivers/accel/qda/qda_ioctl.c
@@ -0,0 +1,45 @@
+// SPDX-License-Identifier: GPL-2.0-only
+// Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
+#include <drm/drm_ioctl.h>
+#include <drm/drm_gem.h>
+#include <drm/qda_accel.h>
+#include "qda_drv.h"
+#include "qda_ioctl.h"
+
+static int qda_validate_and_get_context(struct drm_device *dev, struct drm_file *file_priv,
+					struct qda_dev **qdev, struct qda_user **qda_user)
+{
+	struct qda_drm_priv *drm_priv = dev->dev_private;
+	struct qda_file_priv *qda_file_priv;
+
+	if (!drm_priv)
+		return -EINVAL;
+
+	*qdev = drm_priv->qdev;
+	if (!*qdev)
+		return -EINVAL;
+
+	qda_file_priv = (struct qda_file_priv *)file_priv->driver_priv;
+	if (!qda_file_priv || !qda_file_priv->qda_user)
+		return -EINVAL;
+
+	*qda_user = qda_file_priv->qda_user;
+
+	return 0;
+}
+
+int qda_ioctl_query(struct drm_device *dev, void *data, struct drm_file *file_priv)
+{
+	struct qda_dev *qdev;
+	struct qda_user *qda_user;
+	struct drm_qda_query *args = data;
+	int ret;
+
+	ret = qda_validate_and_get_context(dev, file_priv, &qdev, &qda_user);
+	if (ret)
+		return ret;
+
+	strscpy(args->dsp_name, qdev->dsp_name, sizeof(args->dsp_name));
+
+	return 0;
+}
diff --git a/drivers/accel/qda/qda_ioctl.h b/drivers/accel/qda/qda_ioctl.h
new file mode 100644
index 000000000000..6bf3bcd28c0e
--- /dev/null
+++ b/drivers/accel/qda/qda_ioctl.h
@@ -0,0 +1,26 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
+ */
+
+#ifndef _QDA_IOCTL_H
+#define _QDA_IOCTL_H
+
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <drm/drm_ioctl.h>
+#include "qda_drv.h"
+
+/**
+ * qda_ioctl_query - Query DSP device information and capabilities
+ * @dev: DRM device structure
+ * @data: User-space data containing query parameters and results
+ * @file_priv: DRM file private data
+ *
+ * This IOCTL handler queries information about the DSP device.
+ *
+ * Return: 0 on success, negative error code on failure
+ */
+int qda_ioctl_query(struct drm_device *dev, void *data, struct drm_file *file_priv);
+
+#endif /* _QDA_IOCTL_H */
diff --git a/include/uapi/drm/qda_accel.h b/include/uapi/drm/qda_accel.h
new file mode 100644
index 000000000000..0aad791c4832
--- /dev/null
+++ b/include/uapi/drm/qda_accel.h
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0-only WITH Linux-syscall-note */
+/*
+ * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
+ */
+
+#ifndef __QDA_ACCEL_H__
+#define __QDA_ACCEL_H__
+
+#include "drm.h"
+
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
+/*
+ * QDA IOCTL command numbers
+ *
+ * These define the command numbers for QDA-specific IOCTLs.
+ * They are used with DRM_COMMAND_BASE to create the full IOCTL numbers.
+ */
+#define DRM_QDA_QUERY	0x00
+/*
+ * QDA IOCTL definitions
+ *
+ * These macros define the actual IOCTL numbers used by userspace applications.
+ * They combine the command numbers with DRM_COMMAND_BASE and specify the
+ * data structure and direction (read/write) for each IOCTL.
+ */
+#define DRM_IOCTL_QDA_QUERY	DRM_IOR(DRM_COMMAND_BASE + DRM_QDA_QUERY, struct drm_qda_query)
+
+/**
+ * struct drm_qda_query - Device information query structure
+ * @dsp_name: Name of DSP (e.g., "adsp", "cdsp", "cdsp1", "gdsp0", "gdsp1")
+ *
+ * This structure is used with DRM_IOCTL_QDA_QUERY to query device type,
+ * allowing userspace to identify which DSP a device node represents. The
+ * kernel provides the DSP name directly as a null-terminated string.
+ */
+struct drm_qda_query {
+	__u8 dsp_name[16];
+};
+
+#if defined(__cplusplus)
+}
+#endif
+
+#endif /* __QDA_ACCEL_H__ */

-- 
2.34.1