[PATCH v2 08/15] accel/qda: Add QUERY IOCTL and QDA UAPI header

[Ekansh Gupta <ekansh.gupta@oss.qualcomm.com>]

Introduce DRM_IOCTL_QDA_QUERY, a query IOCTL that lets user-space
retrieve information about the DSP a given /dev/accel/accel* node
represents.

The IOCTL takes a query_type selector as input, so it can be extended
to return additional parameters (capabilities, attributes) in the
future without adding new IOCTLs: drm_ioctl() zero-extends the argument
structure, so new fields can be appended to struct drm_qda_query as
long as they go at the end. The first supported query,
QDA_QUERY_DSP_NAME, returns the DSP domain name (e.g. "cdsp", "adsp").

The UAPI header include/uapi/drm/qda_accel.h defines the command number,
the DRM_IOWR IOCTL definition, the query_type values, and struct
drm_qda_query. It follows the standard DRM UAPI conventions: fixed-width
types, a C++ extern "C" guard, and GPL-2.0-only WITH Linux-syscall-note
licensing.

qda_ioctl_query() validates the reserved pad field, dispatches on
query_type, and copies the DSP name from qda_dev.dsp_name into the
user-supplied buffer with strscpy(). Unknown query types are rejected
with -EINVAL.

qda_drv.c registers the qda_ioctls[] table with the drm_driver so the
DRM core dispatches DRM_IOCTL_QDA_QUERY to qda_ioctl_query().

Assisted-by: Claude:claude-sonnet-5
Signed-off-by: Ekansh Gupta <ekansh.gupta@oss.qualcomm.com>
---
Changes in v2:
- Add a query_type input selector so the IOCTL can return different
  parameters in future, and switch DRM_IOR -> DRM_IOWR so the input
  reaches the kernel (Dmitry Baryshkov)
- Reject unknown query types and a non-zero pad with -EINVAL
---
 drivers/accel/qda/Makefile    |  1 +
 drivers/accel/qda/qda_drv.c   |  8 +++++++
 drivers/accel/qda/qda_ioctl.c | 35 +++++++++++++++++++++++++++
 drivers/accel/qda/qda_ioctl.h | 13 ++++++++++
 include/uapi/drm/qda_accel.h  | 55 +++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 112 insertions(+)

diff --git a/drivers/accel/qda/Makefile b/drivers/accel/qda/Makefile
index 701fad5ffb50..b658dad35fee 100644
--- a/drivers/accel/qda/Makefile
+++ b/drivers/accel/qda/Makefile
@@ -8,6 +8,7 @@ obj-$(CONFIG_DRM_ACCEL_QDA)	:= qda.o
 qda-y := \
 	qda_cb.o \
 	qda_drv.o \
+	qda_ioctl.o \
 	qda_memory_manager.o \
 	qda_rpmsg.o
 
diff --git a/drivers/accel/qda/qda_drv.c b/drivers/accel/qda/qda_drv.c
index fdc909facd95..e1fd8bfa12d7 100644
--- a/drivers/accel/qda/qda_drv.c
+++ b/drivers/accel/qda/qda_drv.c
@@ -8,8 +8,10 @@
 #include <drm/drm_gem.h>
 #include <drm/drm_ioctl.h>
 #include <drm/drm_print.h>
+#include <drm/qda_accel.h>
 
 #include "qda_drv.h"
+#include "qda_ioctl.h"
 
 static int qda_open(struct drm_device *dev, struct drm_file *file)
 {
@@ -35,11 +37,17 @@ 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 const 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 = QDA_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..c1d6c9bc0465
--- /dev/null
+++ b/drivers/accel/qda/qda_ioctl.c
@@ -0,0 +1,35 @@
+// SPDX-License-Identifier: GPL-2.0-only
+// Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
+#include <drm/drm_ioctl.h>
+#include <drm/qda_accel.h>
+#include "qda_drv.h"
+#include "qda_ioctl.h"
+
+/**
+ * qda_ioctl_query() - Query DSP device information
+ * @dev: DRM device structure
+ * @data: User-space data (struct drm_qda_query)
+ * @file_priv: DRM file private data
+ *
+ * Return: 0 on success, negative error code on failure
+ */
+int qda_ioctl_query(struct drm_device *dev, void *data, struct drm_file *file_priv)
+{
+	struct drm_qda_query *args = data;
+	struct qda_dev *qdev;
+
+	if (args->pad)
+		return -EINVAL;
+
+	qdev = qda_dev_from_drm(dev);
+
+	switch (args->query_type) {
+	case QDA_QUERY_DSP_NAME:
+		strscpy(args->dsp_name, qdev->dsp_name, sizeof(args->dsp_name));
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
diff --git a/drivers/accel/qda/qda_ioctl.h b/drivers/accel/qda/qda_ioctl.h
new file mode 100644
index 000000000000..b8fd536a111f
--- /dev/null
+++ b/drivers/accel/qda/qda_ioctl.h
@@ -0,0 +1,13 @@
+/* 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 "qda_drv.h"
+
+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..fe695347762c
--- /dev/null
+++ b/include/uapi/drm/qda_accel.h
@@ -0,0 +1,55 @@
+/* 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_IOWR(DRM_COMMAND_BASE + DRM_QDA_QUERY, \
+					 struct drm_qda_query)
+
+/* Query type definitions for drm_qda_query */
+#define QDA_QUERY_DSP_NAME	1
+
+/**
+ * struct drm_qda_query - Device information query structure
+ * @query_type: Type of query (input)
+ * @pad: Padding for 64-bit alignment (must be zero)
+ * @dsp_name: Null-terminated name of the DSP (returned when query_type is QDA_QUERY_DSP_NAME)
+ *
+ * This structure is used with DRM_IOCTL_QDA_QUERY to query device attributes
+ * based on @query_type.
+ */
+struct drm_qda_query {
+	__u32 query_type;
+	__u32 pad;
+	__u8 dsp_name[16];
+};
+
+#if defined(__cplusplus)
+}
+#endif
+
+#endif /* __QDA_ACCEL_H__ */

-- 
2.34.1