accel: add accel dummy driveraccel_v2

This commit is only intended as a reference of how to add a new
accelerator driver. It is not intended to be merged.

The dummy driver defines the new DRIVER_COMPUTE_ACCEL flag as its
feature and registers to the drm subsystem.

Signed-off-by: Oded Gabbay <ogabbay@kernel.org>

5 files changed, 144 insertions, 0 deletions

diff --git a/drivers/accel/Kconfig b/drivers/accel/Kconfig
index 282ea24f90c571..588f311094459c 100644
--- a/drivers/accel/Kconfig
+++ b/drivers/accel/Kconfig
@@ -22,3 +22,5 @@ menuconfig ACCEL
 	  major number than GPUs, and will be exposed to user-space using
 	  different device files, called accel/accel* (in /dev, sysfs
 	  and debugfs)
+
+source "drivers/accel/dummy/Kconfig"
diff --git a/drivers/accel/Makefile b/drivers/accel/Makefile
index b5b7d812a8ef1b..171191ed6ab167 100644
--- a/drivers/accel/Makefile
+++ b/drivers/accel/Makefile
@@ -8,3 +8,6 @@ accel-y := \
 	accel_drv.o
 
 obj-$(CONFIG_ACCEL)	+= accel.o
+
+obj-$(CONFIG_ACCEL_DUMMY)		+= dummy/
+
diff --git a/drivers/accel/dummy/Kconfig b/drivers/accel/dummy/Kconfig
new file mode 100644
index 00000000000000..7723d4cd8ce899
--- /dev/null
+++ b/drivers/accel/dummy/Kconfig
@@ -0,0 +1,15 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+config ACCEL_DUMMY
+	tristate "Drive for a dummy compute accelerator"
+	depends on ACCEL
+	help
+	  An example of a compute accelerator driver that registers with drm
+	  as a compute accelerator.
+
+	  This driver does not actually do anything.
+
+	  If unsure, say N.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called accel_dummy.
diff --git a/drivers/accel/dummy/Makefile b/drivers/accel/dummy/Makefile
new file mode 100644
index 00000000000000..c2b9706bffe50f
--- /dev/null
+++ b/drivers/accel/dummy/Makefile
@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+accel_dummy-y += dummy_drv.o
+
+obj-$(CONFIG_ACCEL_DUMMY) := accel_dummy.o
diff --git a/drivers/accel/dummy/dummy_drv.c b/drivers/accel/dummy/dummy_drv.c
new file mode 100644
index 00000000000000..da516f7f9b4f18
--- /dev/null
+++ b/drivers/accel/dummy/dummy_drv.c
@@ -0,0 +1,119 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+#include <drm/drm_accel.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_ioctl.h>
+#include <drm/drm_print.h>
+
+#define DRIVER_NAME	"accel_dummy"
+#define DRIVER_DESC	"Driver for a dummy compute accelerator"
+#define DRIVER_DATE	"20221022"
+#define DRIVER_MAJOR	1
+#define DRIVER_MINOR	0
+
+MODULE_AUTHOR("Oded Gabbay");
+MODULE_DESCRIPTION("Driver for a dummy compute accelerator");
+MODULE_LICENSE("GPL");
+
+struct accel_dummy_device {
+	struct drm_device drm;
+	struct platform_device *platform;
+};
+
+static struct accel_dummy_device *add;
+
+static void accel_dummy_release(struct drm_device *dev)
+{
+	DRM_INFO("%s called", __func__);
+}
+
+static void accel_dummy_debugfs_init(struct drm_minor *minor)
+{
+	DRM_INFO("%s called", __func__);
+}
+
+static const struct file_operations accel_dummy_driver_fops = {
+	.owner = THIS_MODULE,
+	.open = accel_open,
+	.release = drm_release,
+	.unlocked_ioctl = drm_ioctl,
+	.poll = drm_poll,
+	.read = drm_read,
+	.llseek = noop_llseek
+};
+
+static const struct drm_driver accel_dummy_driver = {
+	.driver_features	= DRIVER_COMPUTE_ACCEL,
+	.release		= accel_dummy_release,
+	.fops			= &accel_dummy_driver_fops,
+	.debugfs_init           = accel_dummy_debugfs_init,
+	.name			= DRIVER_NAME,
+	.desc			= DRIVER_DESC,
+	.date			= DRIVER_DATE,
+	.major			= DRIVER_MAJOR,
+	.minor			= DRIVER_MINOR,
+};
+
+static void __exit accel_dummy_exit(void)
+{
+	struct platform_device *pdev;
+
+	DRM_INFO("%s called", __func__);
+
+	if (IS_ERR_OR_NULL(add)) {
+		DRM_INFO("accel_dummy_device wasn't initialized\n");
+		return;
+	}
+
+	pdev = add->platform;
+
+	drm_dev_unregister(&add->drm);
+	devres_release_group(&pdev->dev, NULL);
+	platform_device_unregister(pdev);
+
+	kfree(add);
+	add = NULL;
+}
+
+static int __init accel_dummy_init(void)
+{
+	struct platform_device *pdev;
+	int ret;
+
+	DRM_INFO("%s called", __func__);
+
+	pdev = platform_device_register_simple(DRIVER_NAME, -1, NULL, 0);
+	if (IS_ERR(pdev))
+		return PTR_ERR(pdev);
+
+	if (!devres_open_group(&pdev->dev, NULL, GFP_KERNEL)) {
+		ret = -ENOMEM;
+		goto out_unregister;
+	}
+
+	add = devm_drm_dev_alloc(&pdev->dev, &accel_dummy_driver,
+				struct accel_dummy_device, drm);
+	if (IS_ERR(add)) {
+		ret = PTR_ERR(add);
+		goto out_devres;
+	}
+	add->platform = pdev;
+
+	ret = drm_dev_register(&add->drm, 0);
+	if (ret)
+		goto out_devres;
+
+	return 0;
+
+out_devres:
+	devres_release_group(&pdev->dev, NULL);
+out_unregister:
+	platform_device_unregister(pdev);
+	return ret;
+}
+
+module_init(accel_dummy_init);
+module_exit(accel_dummy_exit);