[PATCH v4 05/25] accel/qda: Add UAPI header and DSP query ioctl

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

A system has one accel node per DSP domain, and which node is which is
not something user space can tell from the node name: /dev/accel/accel0
may be the CDSP on one platform and the ADSP on another. An application
that wants a particular DSP has to open the nodes and ask.

Add DRM_IOCTL_QDA_QUERY, which returns the name of the DSP behind a
given node, taken from the "label" property of its device tree node.
The ioctl takes a query_type selector so that later additions (DSP
capabilities, attributes) do not each need an ioctl of their own, and
is DRM_IOWR rather than DRM_IOR so that the selector reaches the
kernel.

Unknown query types are rejected with -EINVAL rather than returning
zeroes, so that user space can tell an unsupported query on an old
kernel apart from a query that legitimately returned nothing.

Signed-off-by: Ekansh Gupta <ekansh.gupta@oss.qualcomm.com>
---
 MAINTAINERS                   |  1 +
 drivers/accel/qda/Makefile    |  1 +
 drivers/accel/qda/qda_drv.c   |  8 ++++++++
 drivers/accel/qda/qda_ioctl.c | 30 ++++++++++++++++++++++++++++++
 drivers/accel/qda/qda_ioctl.h | 13 +++++++++++++
 include/uapi/drm/qda_accel.h  | 41 +++++++++++++++++++++++++++++++++++++++++
 6 files changed, 94 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 77687a35ac13..1316e63c1151 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -22982,6 +22982,7 @@ S:	Supported
 T:	git https://gitlab.freedesktop.org/drm/misc/kernel.git
 F:	Documentation/accel/qda/
 F:	drivers/accel/qda/
+F:	include/uapi/drm/qda_accel.h
 
 QUALCOMM EMAC GIGABIT ETHERNET DRIVER
 M:	Timur Tabi <timur@kernel.org>
diff --git a/drivers/accel/qda/Makefile b/drivers/accel/qda/Makefile
index 1ca991e198ed..402e7dbebbf0 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 \
 	qda_soc.o
diff --git a/drivers/accel/qda/qda_drv.c b/drivers/accel/qda/qda_drv.c
index a99e23933f6b..e722135238f3 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 struct qda_session *qda_session_alloc(struct qda_dev *qdev)
 {
@@ -54,11 +56,17 @@ 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..380c2526d9d2
--- /dev/null
+++ b/drivers/accel/qda/qda_ioctl.c
@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: GPL-2.0-only
+// Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
+#include <linux/string.h>
+#include <drm/drm_device.h>
+#include <drm/drm_file.h>
+#include <drm/qda_accel.h>
+#include "qda_drv.h"
+#include "qda_ioctl.h"
+
+/**
+ * qda_ioctl_query() - Query a property of the DSP
+ * @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 qda_dev *qdev = qda_dev_from_drm(dev);
+	struct drm_qda_query *args = data;
+
+	switch (args->query_type) {
+	case QDA_QUERY_DSP_NAME:
+		strscpy(args->dsp_name, qdev->dsp_name, sizeof(args->dsp_name));
+		return 0;
+	default:
+		return -EINVAL;
+	}
+}
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..b9dc4787bd42
--- /dev/null
+++ b/include/uapi/drm/qda_accel.h
@@ -0,0 +1,41 @@
+/* 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
+
+#define DRM_QDA_QUERY		0x00
+
+#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)
+ * @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;
+	__u8 dsp_name[16];
+};
+
+#if defined(__cplusplus)
+}
+#endif
+
+#endif /* __QDA_ACCEL_H__ */

-- 
2.34.1