Re: [PATCH] drm/vkms: Introduce basic VKMS driver

[Daniel Vetter <daniel@ffwll.ch>]

On Mon, May 14, 2018 at 05:33:46PM +0300, Haneen Mohammed wrote:
> This patch introduces Virtual Kernel Mode-Setting (VKMS) driver. It
> creates a very basic kms driver with 1 crtc/encoder/connector/plane.
> 
> VKMS driver would be useful for testing, or for running X (or similar)
> on headless machines and be able to still use the GPU. Thus it enables
> a virtual display without the need for hardware display capability.
> 
> Signed-off-by: Haneen Mohammed <hamohammed.sa@gmail.com>

Created a new topic branch topic/vkms in drm-misc and pushed it there.

Thanks, Daniel

> ---
>  drivers/gpu/drm/Kconfig         |   6 ++
>  drivers/gpu/drm/Makefile        |   1 +
>  drivers/gpu/drm/vkms/Makefile   |   3 +
>  drivers/gpu/drm/vkms/vkms_drv.c | 146 ++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/vkms/vkms_drv.h |  13 +++
>  5 files changed, 169 insertions(+)
>  create mode 100644 drivers/gpu/drm/vkms/Makefile
>  create mode 100644 drivers/gpu/drm/vkms/vkms_drv.c
>  create mode 100644 drivers/gpu/drm/vkms/vkms_drv.h
> 
> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> index 2a72d2feb76d..7db3d82cbb27 100644
> --- a/drivers/gpu/drm/Kconfig
> +++ b/drivers/gpu/drm/Kconfig
> @@ -213,6 +213,12 @@ config DRM_VGEM
>  	  as used by Mesa's software renderer for enhanced performance.
>  	  If M is selected the module will be called vgem.
>  
> +config DRM_VKMS
> +	tristate "Virtual KMS"
> +	depends on DRM
> +	help
> +	  Choose this option to get a virtual kernal mode-setting driver.
> +	  If M is selected the module will be called vkms.
>  
>  source "drivers/gpu/drm/exynos/Kconfig"
>  
> diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
> index ef9f3dab287f..8873d4769116 100644
> --- a/drivers/gpu/drm/Makefile
> +++ b/drivers/gpu/drm/Makefile
> @@ -69,6 +69,7 @@ obj-$(CONFIG_DRM_SAVAGE)+= savage/
>  obj-$(CONFIG_DRM_VMWGFX)+= vmwgfx/
>  obj-$(CONFIG_DRM_VIA)	+=via/
>  obj-$(CONFIG_DRM_VGEM)	+= vgem/
> +obj-$(CONFIG_DRM_VKMS)	+= vkms/
>  obj-$(CONFIG_DRM_NOUVEAU) +=nouveau/
>  obj-$(CONFIG_DRM_EXYNOS) +=exynos/
>  obj-$(CONFIG_DRM_ROCKCHIP) +=rockchip/
> diff --git a/drivers/gpu/drm/vkms/Makefile b/drivers/gpu/drm/vkms/Makefile
> new file mode 100644
> index 000000000000..2aef948d3a34
> --- /dev/null
> +++ b/drivers/gpu/drm/vkms/Makefile
> @@ -0,0 +1,3 @@
> +vkms-y := vkms_drv.o
> +
> +obj-$(CONFIG_DRM_VKMS) += vkms.o
> diff --git a/drivers/gpu/drm/vkms/vkms_drv.c b/drivers/gpu/drm/vkms/vkms_drv.c
> new file mode 100644
> index 000000000000..b1df08ed23a0
> --- /dev/null
> +++ b/drivers/gpu/drm/vkms/vkms_drv.c
> @@ -0,0 +1,146 @@
> +/*
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + */
> +
> +#include <linux/module.h>
> +#include <drm/drmP.h>
> +#include <drm/drm_gem.h>
> +#include <drm/drm_crtc_helper.h>
> +#include "vkms_drv.h"
> +
> +#define DRIVER_NAME	"vkms"
> +#define DRIVER_DESC	"Virtual Kernel Mode Setting"
> +#define DRIVER_DATE	"20180514"
> +#define DRIVER_MAJOR	1
> +#define DRIVER_MINOR	0
> +
> +static struct vkms_device *vkms_device;
> +
> +static const struct file_operations vkms_driver_fops = {
> +	.owner		= THIS_MODULE,
> +	.open		= drm_open,
> +	.mmap		= drm_gem_mmap,
> +	.unlocked_ioctl	= drm_ioctl,
> +	.compat_ioctl	= drm_compat_ioctl,
> +	.poll		= drm_poll,
> +	.read		= drm_read,
> +	.llseek		= no_llseek,
> +	.release	= drm_release,
> +};
> +
> +static void vkms_release(struct drm_device *dev)
> +{
> +	struct vkms_device *vkms = container_of(dev, struct vkms_device, drm);
> +
> +	platform_device_unregister(vkms->platform);
> +	drm_mode_config_cleanup(&vkms->drm);
> +	drm_dev_fini(&vkms->drm);
> +}
> +
> +struct drm_driver vkms_driver = {
> +	.driver_features	= DRIVER_MODESET | DRIVER_ATOMIC | DRIVER_GEM,
> +	.release		= vkms_release,
> +	.fops			= &vkms_driver_fops,
> +
> +	.name			= DRIVER_NAME,
> +	.desc			= DRIVER_DESC,
> +	.date			= DRIVER_DATE,
> +	.major			= DRIVER_MAJOR,
> +	.minor			= DRIVER_MINOR,
> +};
> +
> +static const u32 vkms_formats[] = {
> +	DRM_FORMAT_XRGB8888,
> +};
> +
> +static void vkms_connector_destroy(struct drm_connector *connector)
> +{
> +	drm_connector_unregister(connector);
> +	drm_connector_cleanup(connector);
> +}
> +
> +static const struct drm_connector_funcs vkms_connector_funcs = {
> +	.fill_modes = drm_helper_probe_single_connector_modes,
> +	.destroy = vkms_connector_destroy,
> +};
> +
> +static int __init vkms_init(void)
> +{
> +	int ret;
> +
> +	vkms_device = kzalloc(sizeof(*vkms_device), GFP_KERNEL);
> +	if (!vkms_device)
> +		return -ENOMEM;
> +
> +	ret = drm_dev_init(&vkms_device->drm, &vkms_driver, NULL);
> +	if (ret)
> +		goto out_free;
> +
> +	vkms_device->platform =
> +		platform_device_register_simple(DRIVER_NAME, -1, NULL, 0);
> +	if (IS_ERR(vkms_device->platform)) {
> +		ret = PTR_ERR(vkms_device->platform);
> +		goto out_fini;
> +	}
> +
> +	drm_mode_config_init(&vkms_device->drm);
> +
> +	ret = drm_connector_init(&vkms_device->drm, &vkms_device->connector,
> +				 &vkms_connector_funcs,
> +				 DRM_MODE_CONNECTOR_VIRTUAL);
> +	if (ret < 0) {
> +		DRM_ERROR("Failed to init connector\n");
> +		goto out_unregister;
> +	}
> +
> +	ret = drm_simple_display_pipe_init(&vkms_device->drm,
> +					   &vkms_device->pipe,
> +					   NULL,
> +					   vkms_formats,
> +					   ARRAY_SIZE(vkms_formats),
> +					   NULL,
> +					   &vkms_device->connector);
> +	if (ret < 0) {
> +		DRM_ERROR("Cannot setup simple display pipe\n");
> +		goto out_unregister;
> +	}
> +
> +	ret = drm_dev_register(&vkms_device->drm, 0);
> +	if (ret)
> +		goto out_unregister;
> +
> +	drm_connector_register(&vkms_device->connector);
> +
> +	return 0;
> +
> +out_unregister:
> +	platform_device_unregister(vkms_device->platform);
> +out_fini:
> +	drm_dev_fini(&vkms_device->drm);
> +out_free:
> +	kfree(vkms_device);
> +
> +	return ret;
> +}
> +
> +static void __exit vkms_exit(void)
> +{
> +	if (!vkms_device) {
> +		DRM_INFO("vkms_device is NULL.\n");
> +		return;
> +	}
> +
> +	drm_dev_unregister(&vkms_device->drm);
> +	drm_dev_put(&vkms_device->drm);
> +
> +	kfree(vkms_device);
> +}
> +
> +module_init(vkms_init);
> +module_exit(vkms_exit);
> +
> +MODULE_DESCRIPTION(DRIVER_DESC);
> +MODULE_LICENSE("GPL");
> diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
> new file mode 100644
> index 000000000000..c77c5bf5032a
> --- /dev/null
> +++ b/drivers/gpu/drm/vkms/vkms_drv.h
> @@ -0,0 +1,13 @@
> +#ifndef _VKMS_DRV_H_
> +#define _VKMS_DRV_H_
> +
> +#include <drm/drm_simple_kms_helper.h>
> +
> +struct vkms_device {
> +	struct drm_device drm;
> +	struct platform_device *platform;
> +	struct drm_simple_display_pipe pipe;
> +	struct drm_connector connector;
> +};
> +
> +#endif /* _VKMS_DRV_H_ */
> -- 
> 2.17.0
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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