diff mbox

[v4,1/7] drm: Add DRM support for tiny LCD displays

Message ID 20170211184858.26421-2-noralf@tronnes.org (mailing list archive)
State New, archived
Headers show

Commit Message

Noralf Trønnes Feb. 11, 2017, 6:48 p.m. UTC
tinydrm provides helpers for very simple displays that can use
CMA backed framebuffers and need flushing on changes.

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Thierry Reding <treding@nvidia.com>
---

Changes since version 3:
- Rebase on new drm_fbdev_cma_init_with_funcs() signature

 Documentation/gpu/index.rst                 |   1 +
 Documentation/gpu/tinydrm.rst               |  21 ++
 drivers/gpu/drm/Kconfig                     |   2 +
 drivers/gpu/drm/Makefile                    |   1 +
 drivers/gpu/drm/tinydrm/Kconfig             |   8 +
 drivers/gpu/drm/tinydrm/Makefile            |   1 +
 drivers/gpu/drm/tinydrm/core/Makefile       |   3 +
 drivers/gpu/drm/tinydrm/core/tinydrm-core.c | 376 ++++++++++++++++++++++++++++
 drivers/gpu/drm/tinydrm/core/tinydrm-pipe.c | 234 +++++++++++++++++
 include/drm/tinydrm/tinydrm.h               | 115 +++++++++
 10 files changed, 762 insertions(+)
 create mode 100644 Documentation/gpu/tinydrm.rst
 create mode 100644 drivers/gpu/drm/tinydrm/Kconfig
 create mode 100644 drivers/gpu/drm/tinydrm/Makefile
 create mode 100644 drivers/gpu/drm/tinydrm/core/Makefile
 create mode 100644 drivers/gpu/drm/tinydrm/core/tinydrm-core.c
 create mode 100644 drivers/gpu/drm/tinydrm/core/tinydrm-pipe.c
 create mode 100644 include/drm/tinydrm/tinydrm.h

--
2.10.2

Comments

Andy Shevchenko Feb. 12, 2017, 11:05 a.m. UTC | #1
On Sat, Feb 11, 2017 at 8:48 PM, Noralf Trønnes <noralf@tronnes.org> wrote:
> tinydrm provides helpers for very simple displays that can use
> CMA backed framebuffers and need flushing on changes.

> +/**

> + * tinydrm_gem_cma_free_object - Free resources associated with a CMA GEM
> + *                               object

Keep on one line?

> +const struct file_operations tinydrm_fops = {

> +       .owner          = THIS_MODULE,

Do we still need this?

> +static int tinydrm_init(struct device *parent, struct tinydrm_device *tdev,
> +                       const struct drm_framebuffer_funcs *fb_funcs,
> +                       struct drm_driver *driver)
> +{
> +       struct drm_device *drm;
> +
> +       mutex_init(&tdev->dirty_lock);
> +       tdev->fb_funcs = fb_funcs;
> +
> +       /*
> +        * We don't embed drm_device, because that prevent us from using
> +        * devm_kzalloc() to allocate tinydrm_device in the driver since

> +        * drm_dev_unref() frees the structure. The devm_ functions provide

"devm_ functions" -> "devm_kzalloc()" ?

Otherwise what else do you refer to and why here?

> +        * for easy error handling.
> +        */

> +static int tinydrm_register(struct tinydrm_device *tdev)
> +{
> +       struct drm_device *drm = tdev->drm;
> +       int bpp = drm->mode_config.preferred_depth;
> +       struct drm_fbdev_cma *fbdev;
> +       int ret;
> +
> +       ret = drm_dev_register(tdev->drm, 0);
> +       if (ret)
> +               return ret;
> +
> +       fbdev = drm_fbdev_cma_init_with_funcs(drm, bpp ? bpp : 32,
> +                                             drm->mode_config.num_connector,
> +                                             tdev->fb_funcs);

> +       if (IS_ERR(fbdev))
> +               DRM_ERROR("Failed to initialize fbdev: %ld\n", PTR_ERR(fbdev));
> +       else
> +               tdev->fbdev_cma = fbdev;

Apparently I missed previous round of reviews, can you just put in
short words why error is not propagated here to the caller?

> +
> +       return 0;
> +}

> +/**
> + * tinydrm_display_pipe_init - Initialize display pipe
> + * @tdev: tinydrm device
> + * @funcs: Display pipe functions
> + * @connector_type: Connector type

> + * @formats: Array of supported formats (DRM_FORMAT\_\*)

DRM_FORMAT_* ?

> + * @format_count: Number of elements in @formats
> + * @mode: Supported mode
> + * @rotation: Initial @mode rotation in degrees Counter Clock Wise
> + *
> + * This function sets up a &drm_simple_display_pipe with a &drm_connector that
> + * has one fixed &drm_display_mode which is rotated according to @rotation.
> + *
> + * Returns:
> + * Zero on success, negative error code on failure.
> + */

> +{
> +       struct drm_device *drm = tdev->drm;
> +       struct drm_display_mode *mode_copy;
> +       struct drm_connector *connector;
> +       int ret;

> +       connector = tinydrm_connector_create(drm, mode_copy, connector_type);
> +       if (IS_ERR(connector))
> +               return PTR_ERR(connector);
> +

> +       ret = drm_simple_display_pipe_init(drm, &tdev->pipe, funcs, formats,
> +                                          format_count, connector);
> +       if (ret)
> +               return ret;
> +
> +       return 0;

return drm_... ?

> +}
> +EXPORT_SYMBOL(tinydrm_display_pipe_init);
Noralf Trønnes Feb. 12, 2017, 1:57 p.m. UTC | #2
Den 12.02.2017 12.05, skrev Andy Shevchenko:
> On Sat, Feb 11, 2017 at 8:48 PM, Noralf Trønnes <noralf@tronnes.org> wrote:
>> tinydrm provides helpers for very simple displays that can use
>> CMA backed framebuffers and need flushing on changes.
>> +/**
>> + * tinydrm_gem_cma_free_object - Free resources associated with a CMA GEM
>> + *                               object
> Keep on one line?

That means 81 columns and checkpatch complaint.
This in one of the annoying things about Linux
kernel coding. Always trying
to avoid
breaking up lines.
Because for me it hinders redability.

>> +const struct file_operations tinydrm_fops = {
>> +       .owner          = THIS_MODULE,
> Do we still need this?

Looks like it, see drm_stub_open()

>> +static int tinydrm_init(struct device *parent, struct tinydrm_device *tdev,
>> +                       const struct drm_framebuffer_funcs *fb_funcs,
>> +                       struct drm_driver *driver)
>> +{
>> +       struct drm_device *drm;
>> +
>> +       mutex_init(&tdev->dirty_lock);
>> +       tdev->fb_funcs = fb_funcs;
>> +
>> +       /*
>> +        * We don't embed drm_device, because that prevent us from using
>> +        * devm_kzalloc() to allocate tinydrm_device in the driver since
>> +        * drm_dev_unref() frees the structure. The devm_ functions provide
> "devm_ functions" -> "devm_kzalloc()" ?
>
> Otherwise what else do you refer to and why here?

yes, that last sentence can be dropped.

>> +        * for easy error handling.
>> +        */
>> +static int tinydrm_register(struct tinydrm_device *tdev)
>> +{
>> +       struct drm_device *drm = tdev->drm;
>> +       int bpp = drm->mode_config.preferred_depth;
>> +       struct drm_fbdev_cma *fbdev;
>> +       int ret;
>> +
>> +       ret = drm_dev_register(tdev->drm, 0);
>> +       if (ret)
>> +               return ret;
>> +
>> +       fbdev = drm_fbdev_cma_init_with_funcs(drm, bpp ? bpp : 32,
>> +                                             drm->mode_config.num_connector,
>> +                                             tdev->fb_funcs);
>> +       if (IS_ERR(fbdev))
>> +               DRM_ERROR("Failed to initialize fbdev: %ld\n", PTR_ERR(fbdev));
>> +       else
>> +               tdev->fbdev_cma = fbdev;
> Apparently I missed previous round of reviews, can you just put in
> short words why error is not propagated here to the caller?

A comment might have helped here:
/* fbdev is of minor importance, don't let it stop us */

>> +
>> +       return 0;
>> +}
>> +/**
>> + * tinydrm_display_pipe_init - Initialize display pipe
>> + * @tdev: tinydrm device
>> + * @funcs: Display pipe functions
>> + * @connector_type: Connector type
>> + * @formats: Array of supported formats (DRM_FORMAT\_\*)
> DRM_FORMAT_* ?

sphinx wants it that way.

>> + * @format_count: Number of elements in @formats
>> + * @mode: Supported mode
>> + * @rotation: Initial @mode rotation in degrees Counter Clock Wise
>> + *
>> + * This function sets up a &drm_simple_display_pipe with a &drm_connector that
>> + * has one fixed &drm_display_mode which is rotated according to @rotation.
>> + *
>> + * Returns:
>> + * Zero on success, negative error code on failure.
>> + */
>> +{
>> +       struct drm_device *drm = tdev->drm;
>> +       struct drm_display_mode *mode_copy;
>> +       struct drm_connector *connector;
>> +       int ret;
>> +       connector = tinydrm_connector_create(drm, mode_copy, connector_type);
>> +       if (IS_ERR(connector))
>> +               return PTR_ERR(connector);
>> +
>> +       ret = drm_simple_display_pipe_init(drm, &tdev->pipe, funcs, formats,
>> +                                          format_count, connector);
>> +       if (ret)
>> +               return ret;
>> +
>> +       return 0;
> return drm_... ?

Yep.


tinydrm will be merged the way it is now, unless someone points to
something that is broken. But I collect your comments for a later
cleanup patchset. It takes a lot of effort for me as an amateur to
keeps this code up-to-date out-of-tree for months. It's not even
sure that I've hit the mark with this, so there will most likely be
changes when I start converting fbtft drivers, and I'll implement the
remaining bits and pieces as I make changes. The core of tinydrm won't
change because of unforseen fbtft quirks, but other parts might.


Noralf.

>> +}
>> +EXPORT_SYMBOL(tinydrm_display_pipe_init);
Daniel Vetter Feb. 14, 2017, 7:54 p.m. UTC | #3
On Sun, Feb 12, 2017 at 2:57 PM, Noralf Trønnes <noralf@tronnes.org> wrote:
> tinydrm will be merged the way it is now, unless someone points to
> something that is broken. But I collect your comments for a later
> cleanup patchset. It takes a lot of effort for me as an amateur to
> keeps this code up-to-date out-of-tree for months. It's not even
> sure that I've hit the mark with this, so there will most likely be
> changes when I start converting fbtft drivers, and I'll implement the
> remaining bits and pieces as I make changes. The core of tinydrm won't
> change because of unforseen fbtft quirks, but other parts might.

+1, pls send pull request to Dave Airlie. DT-acks are all there, and
Thierry confirmed on irc that his reply on the last thread was indeed
meant as a full ack for going ahead and polishing later. I also
chatted with Dave directly, and he's perfectly happy to take this in
as-is. If you do this soon, should still easily get into 4.11 (since
the 4.10 release is delayed).

Cheers, Daniel
Daniel Vetter March 7, 2017, 10:21 p.m. UTC | #4
On Sat, Feb 11, 2017 at 07:48:52PM +0100, Noralf Trønnes wrote:
> +const struct file_operations tinydrm_fops = {
> +	.owner		= THIS_MODULE,
> +	.open		= drm_open,
> +	.release	= drm_release,
> +	.unlocked_ioctl	= drm_ioctl,
> +#ifdef CONFIG_COMPAT
> +	.compat_ioctl	= drm_compat_ioctl,
> +#endif
> +	.poll		= drm_poll,
> +	.read		= drm_read,
> +	.llseek		= no_llseek,
> +	.mmap		= drm_gem_cma_mmap,
> +};
> +EXPORT_SYMBOL(tinydrm_fops);

Just spotted this while doing a drive-by refactoring, this doesn't really
work. The THIS_MODULE must be in the source code for your driver, and
can't be in some helper library module like tinydrm.ko.

I'm working on a macro to make this easier, and I guess you could try to
integrate that into your driver macro somehow (probably simplest to
generate the entire structure and just pass name+desc to that macro,
everything else is boilerplate anyway).

I'll cc you on that patch.
-Daniel
Noralf Trønnes March 8, 2017, 12:23 p.m. UTC | #5
Den 07.03.2017 23.21, skrev Daniel Vetter:
> On Sat, Feb 11, 2017 at 07:48:52PM +0100, Noralf Trønnes wrote:
>> +const struct file_operations tinydrm_fops = {
>> +	.owner		= THIS_MODULE,
>> +	.open		= drm_open,
>> +	.release	= drm_release,
>> +	.unlocked_ioctl	= drm_ioctl,
>> +#ifdef CONFIG_COMPAT
>> +	.compat_ioctl	= drm_compat_ioctl,
>> +#endif
>> +	.poll		= drm_poll,
>> +	.read		= drm_read,
>> +	.llseek		= no_llseek,
>> +	.mmap		= drm_gem_cma_mmap,
>> +};
>> +EXPORT_SYMBOL(tinydrm_fops);
> Just spotted this while doing a drive-by refactoring, this doesn't really
> work. The THIS_MODULE must be in the source code for your driver, and
> can't be in some helper library module like tinydrm.ko.

Yeah, you're right.

> I'm working on a macro to make this easier, and I guess you could try to
> integrate that into your driver macro somehow (probably simplest to
> generate the entire structure and just pass name+desc to that macro,
> everything else is boilerplate anyway).
>
> I'll cc you on that patch.

Thanks.

Noralf.
diff mbox

Patch

diff --git a/Documentation/gpu/index.rst b/Documentation/gpu/index.rst
index 367d7c3..f81278a 100644
--- a/Documentation/gpu/index.rst
+++ b/Documentation/gpu/index.rst
@@ -11,6 +11,7 @@  Linux GPU Driver Developer's Guide
    drm-kms-helpers
    drm-uapi
    i915
+   tinydrm
    vga-switcheroo
    vgaarbiter

diff --git a/Documentation/gpu/tinydrm.rst b/Documentation/gpu/tinydrm.rst
new file mode 100644
index 0000000..ec4a20d
--- /dev/null
+++ b/Documentation/gpu/tinydrm.rst
@@ -0,0 +1,21 @@ 
+==========================
+drm/tinydrm Driver library
+==========================
+
+.. kernel-doc:: drivers/gpu/drm/tinydrm/core/tinydrm-core.c
+   :doc: overview
+
+Core functionality
+==================
+
+.. kernel-doc:: drivers/gpu/drm/tinydrm/core/tinydrm-core.c
+   :doc: core
+
+.. kernel-doc:: include/drm/tinydrm/tinydrm.h
+   :internal:
+
+.. kernel-doc:: drivers/gpu/drm/tinydrm/core/tinydrm-core.c
+   :export:
+
+.. kernel-doc:: drivers/gpu/drm/tinydrm/core/tinydrm-pipe.c
+   :export:
diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index 90bc65d..88e01e08e 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -263,6 +263,8 @@  source "drivers/gpu/drm/mxsfb/Kconfig"

 source "drivers/gpu/drm/meson/Kconfig"

+source "drivers/gpu/drm/tinydrm/Kconfig"
+
 # Keep legacy drivers last

 menuconfig DRM_LEGACY
diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
index 92de399..3ee9579 100644
--- a/drivers/gpu/drm/Makefile
+++ b/drivers/gpu/drm/Makefile
@@ -94,3 +94,4 @@  obj-$(CONFIG_DRM_ARCPGU)+= arc/
 obj-y			+= hisilicon/
 obj-$(CONFIG_DRM_ZTE)	+= zte/
 obj-$(CONFIG_DRM_MXSFB)	+= mxsfb/
+obj-$(CONFIG_DRM_TINYDRM) += tinydrm/
diff --git a/drivers/gpu/drm/tinydrm/Kconfig b/drivers/gpu/drm/tinydrm/Kconfig
new file mode 100644
index 0000000..ffb873f
--- /dev/null
+++ b/drivers/gpu/drm/tinydrm/Kconfig
@@ -0,0 +1,8 @@ 
+menuconfig DRM_TINYDRM
+	tristate "Support for simple displays"
+	depends on DRM
+	select DRM_KMS_HELPER
+	select DRM_KMS_CMA_HELPER
+	help
+	  Choose this option if you have a tinydrm supported display.
+	  If M is selected the module will be called tinydrm.
diff --git a/drivers/gpu/drm/tinydrm/Makefile b/drivers/gpu/drm/tinydrm/Makefile
new file mode 100644
index 0000000..7476ed1
--- /dev/null
+++ b/drivers/gpu/drm/tinydrm/Makefile
@@ -0,0 +1 @@ 
+obj-$(CONFIG_DRM_TINYDRM)		+= core/
diff --git a/drivers/gpu/drm/tinydrm/core/Makefile b/drivers/gpu/drm/tinydrm/core/Makefile
new file mode 100644
index 0000000..4f14a0f
--- /dev/null
+++ b/drivers/gpu/drm/tinydrm/core/Makefile
@@ -0,0 +1,3 @@ 
+tinydrm-y := tinydrm-core.o tinydrm-pipe.o
+
+obj-$(CONFIG_DRM_TINYDRM) += tinydrm.o
diff --git a/drivers/gpu/drm/tinydrm/core/tinydrm-core.c b/drivers/gpu/drm/tinydrm/core/tinydrm-core.c
new file mode 100644
index 0000000..6a257dd
--- /dev/null
+++ b/drivers/gpu/drm/tinydrm/core/tinydrm-core.c
@@ -0,0 +1,376 @@ 
+/*
+ * Copyright (C) 2016 Noralf Trønnes
+ *
+ * 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 <drm/drm_atomic.h>
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_crtc_helper.h>
+#include <drm/tinydrm/tinydrm.h>
+#include <linux/device.h>
+#include <linux/dma-buf.h>
+
+/**
+ * DOC: overview
+ *
+ * This library provides driver helpers for very simple display hardware.
+ *
+ * It is based on &drm_simple_display_pipe coupled with a &drm_connector which
+ * has only one fixed &drm_display_mode. The framebuffers are backed by the
+ * cma helper and have support for framebuffer flushing (dirty).
+ * fbdev support is also included.
+ *
+ */
+
+/**
+ * DOC: core
+ *
+ * The driver allocates &tinydrm_device, initializes it using
+ * devm_tinydrm_init(), sets up the pipeline using tinydrm_display_pipe_init()
+ * and registers the DRM device using devm_tinydrm_register().
+ */
+
+/**
+ * tinydrm_lastclose - DRM lastclose helper
+ * @drm: DRM device
+ *
+ * This function ensures that fbdev is restored when drm_lastclose() is called
+ * on the last drm_release(). Drivers can use this as their
+ * &drm_driver->lastclose callback.
+ */
+void tinydrm_lastclose(struct drm_device *drm)
+{
+	struct tinydrm_device *tdev = drm->dev_private;
+
+	DRM_DEBUG_KMS("\n");
+	drm_fbdev_cma_restore_mode(tdev->fbdev_cma);
+}
+EXPORT_SYMBOL(tinydrm_lastclose);
+
+/**
+ * tinydrm_gem_cma_prime_import_sg_table - Produce a CMA GEM object from
+ *     another driver's scatter/gather table of pinned pages
+ * @drm: DRM device to import into
+ * @attach: DMA-BUF attachment
+ * @sgt: Scatter/gather table of pinned pages
+ *
+ * This function imports a scatter/gather table exported via DMA-BUF by
+ * another driver using drm_gem_cma_prime_import_sg_table(). It sets the
+ * kernel virtual address on the CMA object. Drivers should use this as their
+ * &drm_driver->gem_prime_import_sg_table callback if they need the virtual
+ * address. tinydrm_gem_cma_free_object() should be used in combination with
+ * this function.
+ *
+ * Returns:
+ * A pointer to a newly created GEM object or an ERR_PTR-encoded negative
+ * error code on failure.
+ */
+struct drm_gem_object *
+tinydrm_gem_cma_prime_import_sg_table(struct drm_device *drm,
+				      struct dma_buf_attachment *attach,
+				      struct sg_table *sgt)
+{
+	struct drm_gem_cma_object *cma_obj;
+	struct drm_gem_object *obj;
+	void *vaddr;
+
+	vaddr = dma_buf_vmap(attach->dmabuf);
+	if (!vaddr) {
+		DRM_ERROR("Failed to vmap PRIME buffer\n");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	obj = drm_gem_cma_prime_import_sg_table(drm, attach, sgt);
+	if (IS_ERR(obj)) {
+		dma_buf_vunmap(attach->dmabuf, vaddr);
+		return obj;
+	}
+
+	cma_obj = to_drm_gem_cma_obj(obj);
+	cma_obj->vaddr = vaddr;
+
+	return obj;
+}
+EXPORT_SYMBOL(tinydrm_gem_cma_prime_import_sg_table);
+
+/**
+ * tinydrm_gem_cma_free_object - Free resources associated with a CMA GEM
+ *                               object
+ * @gem_obj: GEM object to free
+ *
+ * This function frees the backing memory of the CMA GEM object, cleans up the
+ * GEM object state and frees the memory used to store the object itself using
+ * drm_gem_cma_free_object(). It also handles PRIME buffers which has the kernel
+ * virtual address set by tinydrm_gem_cma_prime_import_sg_table(). Drivers
+ * can use this as their &drm_driver->gem_free_object callback.
+ */
+void tinydrm_gem_cma_free_object(struct drm_gem_object *gem_obj)
+{
+	if (gem_obj->import_attach) {
+		struct drm_gem_cma_object *cma_obj;
+
+		cma_obj = to_drm_gem_cma_obj(gem_obj);
+		dma_buf_vunmap(gem_obj->import_attach->dmabuf, cma_obj->vaddr);
+		cma_obj->vaddr = NULL;
+	}
+
+	drm_gem_cma_free_object(gem_obj);
+}
+EXPORT_SYMBOL_GPL(tinydrm_gem_cma_free_object);
+
+const struct file_operations tinydrm_fops = {
+	.owner		= THIS_MODULE,
+	.open		= drm_open,
+	.release	= drm_release,
+	.unlocked_ioctl	= drm_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl	= drm_compat_ioctl,
+#endif
+	.poll		= drm_poll,
+	.read		= drm_read,
+	.llseek		= no_llseek,
+	.mmap		= drm_gem_cma_mmap,
+};
+EXPORT_SYMBOL(tinydrm_fops);
+
+static struct drm_framebuffer *
+tinydrm_fb_create(struct drm_device *drm, struct drm_file *file_priv,
+		  const struct drm_mode_fb_cmd2 *mode_cmd)
+{
+	struct tinydrm_device *tdev = drm->dev_private;
+
+	return drm_fb_cma_create_with_funcs(drm, file_priv, mode_cmd,
+					    tdev->fb_funcs);
+}
+
+static const struct drm_mode_config_funcs tinydrm_mode_config_funcs = {
+	.fb_create = tinydrm_fb_create,
+	.atomic_check = drm_atomic_helper_check,
+	.atomic_commit = drm_atomic_helper_commit,
+};
+
+static int tinydrm_init(struct device *parent, struct tinydrm_device *tdev,
+			const struct drm_framebuffer_funcs *fb_funcs,
+			struct drm_driver *driver)
+{
+	struct drm_device *drm;
+
+	mutex_init(&tdev->dirty_lock);
+	tdev->fb_funcs = fb_funcs;
+
+	/*
+	 * We don't embed drm_device, because that prevent us from using
+	 * devm_kzalloc() to allocate tinydrm_device in the driver since
+	 * drm_dev_unref() frees the structure. The devm_ functions provide
+	 * for easy error handling.
+	 */
+	drm = drm_dev_alloc(driver, parent);
+	if (IS_ERR(drm))
+		return PTR_ERR(drm);
+
+	tdev->drm = drm;
+	drm->dev_private = tdev;
+	drm_mode_config_init(drm);
+	drm->mode_config.funcs = &tinydrm_mode_config_funcs;
+
+	return 0;
+}
+
+static void tinydrm_fini(struct tinydrm_device *tdev)
+{
+	drm_mode_config_cleanup(tdev->drm);
+	mutex_destroy(&tdev->dirty_lock);
+	tdev->drm->dev_private = NULL;
+	drm_dev_unref(tdev->drm);
+}
+
+static void devm_tinydrm_release(void *data)
+{
+	tinydrm_fini(data);
+}
+
+/**
+ * devm_tinydrm_init - Initialize tinydrm device
+ * @parent: Parent device object
+ * @tdev: tinydrm device
+ * @fb_funcs: Framebuffer functions
+ * @driver: DRM driver
+ *
+ * This function initializes @tdev, the underlying DRM device and it's
+ * mode_config. Resources will be automatically freed on driver detach (devres)
+ * using drm_mode_config_cleanup() and drm_dev_unref().
+ *
+ * Returns:
+ * Zero on success, negative error code on failure.
+ */
+int devm_tinydrm_init(struct device *parent, struct tinydrm_device *tdev,
+		      const struct drm_framebuffer_funcs *fb_funcs,
+		      struct drm_driver *driver)
+{
+	int ret;
+
+	ret = tinydrm_init(parent, tdev, fb_funcs, driver);
+	if (ret)
+		return ret;
+
+	ret = devm_add_action(parent, devm_tinydrm_release, tdev);
+	if (ret)
+		tinydrm_fini(tdev);
+
+	return ret;
+}
+EXPORT_SYMBOL(devm_tinydrm_init);
+
+static int tinydrm_register(struct tinydrm_device *tdev)
+{
+	struct drm_device *drm = tdev->drm;
+	int bpp = drm->mode_config.preferred_depth;
+	struct drm_fbdev_cma *fbdev;
+	int ret;
+
+	ret = drm_dev_register(tdev->drm, 0);
+	if (ret)
+		return ret;
+
+	fbdev = drm_fbdev_cma_init_with_funcs(drm, bpp ? bpp : 32,
+					      drm->mode_config.num_connector,
+					      tdev->fb_funcs);
+	if (IS_ERR(fbdev))
+		DRM_ERROR("Failed to initialize fbdev: %ld\n", PTR_ERR(fbdev));
+	else
+		tdev->fbdev_cma = fbdev;
+
+	return 0;
+}
+
+static void tinydrm_unregister(struct tinydrm_device *tdev)
+{
+	struct drm_fbdev_cma *fbdev_cma = tdev->fbdev_cma;
+
+	drm_crtc_force_disable_all(tdev->drm);
+	/* don't restore fbdev in lastclose, keep pipeline disabled */
+	tdev->fbdev_cma = NULL;
+	drm_dev_unregister(tdev->drm);
+	if (fbdev_cma)
+		drm_fbdev_cma_fini(fbdev_cma);
+}
+
+static void devm_tinydrm_register_release(void *data)
+{
+	tinydrm_unregister(data);
+}
+
+/**
+ * devm_tinydrm_register - Register tinydrm device
+ * @tdev: tinydrm device
+ *
+ * This function registers the underlying DRM device and fbdev.
+ * These resources will be automatically unregistered on driver detach (devres)
+ * and the display pipeline will be disabled.
+ *
+ * Returns:
+ * Zero on success, negative error code on failure.
+ */
+int devm_tinydrm_register(struct tinydrm_device *tdev)
+{
+	struct device *dev = tdev->drm->dev;
+	int ret;
+
+	ret = tinydrm_register(tdev);
+	if (ret)
+		return ret;
+
+	ret = devm_add_action(dev, devm_tinydrm_register_release, tdev);
+	if (ret)
+		tinydrm_unregister(tdev);
+
+	return ret;
+}
+EXPORT_SYMBOL(devm_tinydrm_register);
+
+/**
+ * tinydrm_shutdown - Shutdown tinydrm
+ * @tdev: tinydrm device
+ *
+ * This function makes sure that the display pipeline is disabled.
+ * Used by drivers in their shutdown callback to turn off the display
+ * on machine shutdown and reboot.
+ */
+void tinydrm_shutdown(struct tinydrm_device *tdev)
+{
+	drm_crtc_force_disable_all(tdev->drm);
+}
+EXPORT_SYMBOL(tinydrm_shutdown);
+
+/**
+ * tinydrm_suspend - Suspend tinydrm
+ * @tdev: tinydrm device
+ *
+ * Used in driver PM operations to suspend tinydrm.
+ * Suspends fbdev and DRM.
+ * Resume with tinydrm_resume().
+ *
+ * Returns:
+ * Zero on success, negative error code on failure.
+ */
+int tinydrm_suspend(struct tinydrm_device *tdev)
+{
+	struct drm_atomic_state *state;
+
+	if (tdev->suspend_state) {
+		DRM_ERROR("Failed to suspend: state already set\n");
+		return -EINVAL;
+	}
+
+	drm_fbdev_cma_set_suspend_unlocked(tdev->fbdev_cma, 1);
+	state = drm_atomic_helper_suspend(tdev->drm);
+	if (IS_ERR(state)) {
+		drm_fbdev_cma_set_suspend_unlocked(tdev->fbdev_cma, 0);
+		return PTR_ERR(state);
+	}
+
+	tdev->suspend_state = state;
+
+	return 0;
+}
+EXPORT_SYMBOL(tinydrm_suspend);
+
+/**
+ * tinydrm_resume - Resume tinydrm
+ * @tdev: tinydrm device
+ *
+ * Used in driver PM operations to resume tinydrm.
+ * Suspend with tinydrm_suspend().
+ *
+ * Returns:
+ * Zero on success, negative error code on failure.
+ */
+int tinydrm_resume(struct tinydrm_device *tdev)
+{
+	struct drm_atomic_state *state = tdev->suspend_state;
+	int ret;
+
+	if (!state) {
+		DRM_ERROR("Failed to resume: state is not set\n");
+		return -EINVAL;
+	}
+
+	tdev->suspend_state = NULL;
+
+	ret = drm_atomic_helper_resume(tdev->drm, state);
+	if (ret) {
+		DRM_ERROR("Error resuming state: %d\n", ret);
+		return ret;
+	}
+
+	drm_fbdev_cma_set_suspend_unlocked(tdev->fbdev_cma, 0);
+
+	return 0;
+}
+EXPORT_SYMBOL(tinydrm_resume);
+
+MODULE_LICENSE("GPL");
diff --git a/drivers/gpu/drm/tinydrm/core/tinydrm-pipe.c b/drivers/gpu/drm/tinydrm/core/tinydrm-pipe.c
new file mode 100644
index 0000000..ec43fb7
--- /dev/null
+++ b/drivers/gpu/drm/tinydrm/core/tinydrm-pipe.c
@@ -0,0 +1,234 @@ 
+/*
+ * Copyright (C) 2016 Noralf Trønnes
+ *
+ * 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 <drm/drm_atomic_helper.h>
+#include <drm/drm_crtc_helper.h>
+#include <drm/drm_modes.h>
+#include <drm/tinydrm/tinydrm.h>
+
+struct tinydrm_connector {
+	struct drm_connector base;
+	const struct drm_display_mode *mode;
+};
+
+static inline struct tinydrm_connector *
+to_tinydrm_connector(struct drm_connector *connector)
+{
+	return container_of(connector, struct tinydrm_connector, base);
+}
+
+static int tinydrm_connector_get_modes(struct drm_connector *connector)
+{
+	struct tinydrm_connector *tconn = to_tinydrm_connector(connector);
+	struct drm_display_mode *mode;
+
+	mode = drm_mode_duplicate(connector->dev, tconn->mode);
+	if (!mode) {
+		DRM_ERROR("Failed to duplicate mode\n");
+		return 0;
+	}
+
+	if (mode->name[0] == '\0')
+		drm_mode_set_name(mode);
+
+	mode->type |= DRM_MODE_TYPE_PREFERRED;
+	drm_mode_probed_add(connector, mode);
+
+	if (mode->width_mm) {
+		connector->display_info.width_mm = mode->width_mm;
+		connector->display_info.height_mm = mode->height_mm;
+	}
+
+	return 1;
+}
+
+static const struct drm_connector_helper_funcs tinydrm_connector_hfuncs = {
+	.get_modes = tinydrm_connector_get_modes,
+	.best_encoder = drm_atomic_helper_best_encoder,
+};
+
+static enum drm_connector_status
+tinydrm_connector_detect(struct drm_connector *connector, bool force)
+{
+	if (drm_device_is_unplugged(connector->dev))
+		return connector_status_disconnected;
+
+	return connector->status;
+}
+
+static void tinydrm_connector_destroy(struct drm_connector *connector)
+{
+	struct tinydrm_connector *tconn = to_tinydrm_connector(connector);
+
+	drm_connector_cleanup(connector);
+	kfree(tconn);
+}
+
+static const struct drm_connector_funcs tinydrm_connector_funcs = {
+	.dpms = drm_atomic_helper_connector_dpms,
+	.reset = drm_atomic_helper_connector_reset,
+	.detect = tinydrm_connector_detect,
+	.fill_modes = drm_helper_probe_single_connector_modes,
+	.destroy = tinydrm_connector_destroy,
+	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
+	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
+};
+
+struct drm_connector *
+tinydrm_connector_create(struct drm_device *drm,
+			 const struct drm_display_mode *mode,
+			 int connector_type)
+{
+	struct tinydrm_connector *tconn;
+	struct drm_connector *connector;
+	int ret;
+
+	tconn = kzalloc(sizeof(*tconn), GFP_KERNEL);
+	if (!tconn)
+		return ERR_PTR(-ENOMEM);
+
+	tconn->mode = mode;
+	connector = &tconn->base;
+
+	drm_connector_helper_add(connector, &tinydrm_connector_hfuncs);
+	ret = drm_connector_init(drm, connector, &tinydrm_connector_funcs,
+				 connector_type);
+	if (ret) {
+		kfree(tconn);
+		return ERR_PTR(ret);
+	}
+
+	connector->status = connector_status_connected;
+
+	return connector;
+}
+
+/**
+ * tinydrm_display_pipe_update - Display pipe update helper
+ * @pipe: Simple display pipe
+ * @old_state: Old plane state
+ *
+ * This function does a full framebuffer flush if the plane framebuffer
+ * has changed. It also handles vblank events. Drivers can use this as their
+ * &drm_simple_display_pipe_funcs->update callback.
+ */
+void tinydrm_display_pipe_update(struct drm_simple_display_pipe *pipe,
+				 struct drm_plane_state *old_state)
+{
+	struct tinydrm_device *tdev = pipe_to_tinydrm(pipe);
+	struct drm_framebuffer *fb = pipe->plane.state->fb;
+	struct drm_crtc *crtc = &tdev->pipe.crtc;
+
+	if (fb && (fb != old_state->fb)) {
+		pipe->plane.fb = fb;
+		if (fb->funcs->dirty)
+			fb->funcs->dirty(fb, NULL, 0, 0, NULL, 0);
+	}
+
+	if (crtc->state->event) {
+		spin_lock_irq(&crtc->dev->event_lock);
+		drm_crtc_send_vblank_event(crtc, crtc->state->event);
+		spin_unlock_irq(&crtc->dev->event_lock);
+		crtc->state->event = NULL;
+	}
+}
+EXPORT_SYMBOL(tinydrm_display_pipe_update);
+
+/**
+ * tinydrm_display_pipe_prepare_fb - Display pipe prepare_fb helper
+ * @pipe: Simple display pipe
+ * @plane_state: Plane state
+ *
+ * This function uses drm_fb_cma_prepare_fb() to check if the plane FB has an
+ * dma-buf attached, extracts the exclusive fence and attaches it to plane
+ * state for the atomic helper to wait on. Drivers can use this as their
+ * &drm_simple_display_pipe_funcs->prepare_fb callback.
+ */
+int tinydrm_display_pipe_prepare_fb(struct drm_simple_display_pipe *pipe,
+				    struct drm_plane_state *plane_state)
+{
+	return drm_fb_cma_prepare_fb(&pipe->plane, plane_state);
+}
+EXPORT_SYMBOL(tinydrm_display_pipe_prepare_fb);
+
+static int tinydrm_rotate_mode(struct drm_display_mode *mode,
+			       unsigned int rotation)
+{
+	if (rotation == 0 || rotation == 180) {
+		return 0;
+	} else if (rotation == 90 || rotation == 270) {
+		swap(mode->hdisplay, mode->vdisplay);
+		swap(mode->hsync_start, mode->vsync_start);
+		swap(mode->hsync_end, mode->vsync_end);
+		swap(mode->htotal, mode->vtotal);
+		swap(mode->width_mm, mode->height_mm);
+		return 0;
+	} else {
+		return -EINVAL;
+	}
+}
+
+/**
+ * tinydrm_display_pipe_init - Initialize display pipe
+ * @tdev: tinydrm device
+ * @funcs: Display pipe functions
+ * @connector_type: Connector type
+ * @formats: Array of supported formats (DRM_FORMAT\_\*)
+ * @format_count: Number of elements in @formats
+ * @mode: Supported mode
+ * @rotation: Initial @mode rotation in degrees Counter Clock Wise
+ *
+ * This function sets up a &drm_simple_display_pipe with a &drm_connector that
+ * has one fixed &drm_display_mode which is rotated according to @rotation.
+ *
+ * Returns:
+ * Zero on success, negative error code on failure.
+ */
+int
+tinydrm_display_pipe_init(struct tinydrm_device *tdev,
+			  const struct drm_simple_display_pipe_funcs *funcs,
+			  int connector_type,
+			  const uint32_t *formats,
+			  unsigned int format_count,
+			  const struct drm_display_mode *mode,
+			  unsigned int rotation)
+{
+	struct drm_device *drm = tdev->drm;
+	struct drm_display_mode *mode_copy;
+	struct drm_connector *connector;
+	int ret;
+
+	mode_copy = devm_kmalloc(drm->dev, sizeof(*mode_copy), GFP_KERNEL);
+	if (!mode_copy)
+		return -ENOMEM;
+
+	*mode_copy = *mode;
+	ret = tinydrm_rotate_mode(mode_copy, rotation);
+	if (ret) {
+		DRM_ERROR("Illegal rotation value %u\n", rotation);
+		return -EINVAL;
+	}
+
+	drm->mode_config.min_width = mode_copy->hdisplay;
+	drm->mode_config.max_width = mode_copy->hdisplay;
+	drm->mode_config.min_height = mode_copy->vdisplay;
+	drm->mode_config.max_height = mode_copy->vdisplay;
+
+	connector = tinydrm_connector_create(drm, mode_copy, connector_type);
+	if (IS_ERR(connector))
+		return PTR_ERR(connector);
+
+	ret = drm_simple_display_pipe_init(drm, &tdev->pipe, funcs, formats,
+					   format_count, connector);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+EXPORT_SYMBOL(tinydrm_display_pipe_init);
diff --git a/include/drm/tinydrm/tinydrm.h b/include/drm/tinydrm/tinydrm.h
new file mode 100644
index 0000000..cf9ca20
--- /dev/null
+++ b/include/drm/tinydrm/tinydrm.h
@@ -0,0 +1,115 @@ 
+/*
+ * Copyright (C) 2016 Noralf Trønnes
+ *
+ * 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.
+ */
+
+#ifndef __LINUX_TINYDRM_H
+#define __LINUX_TINYDRM_H
+
+#include <drm/drm_gem_cma_helper.h>
+#include <drm/drm_fb_cma_helper.h>
+#include <drm/drm_simple_kms_helper.h>
+
+/**
+ * struct tinydrm_device - tinydrm device
+ * @drm: DRM device
+ * @pipe: Display pipe structure
+ * @dirty_lock: Serializes framebuffer flushing
+ * @fbdev_cma: CMA fbdev structure
+ * @suspend_state: Atomic state when suspended
+ * @fb_funcs: Framebuffer functions used when creating framebuffers
+ */
+struct tinydrm_device {
+	struct drm_device *drm;
+	struct drm_simple_display_pipe pipe;
+	struct mutex dirty_lock;
+	struct drm_fbdev_cma *fbdev_cma;
+	struct drm_atomic_state *suspend_state;
+	const struct drm_framebuffer_funcs *fb_funcs;
+};
+
+static inline struct tinydrm_device *
+pipe_to_tinydrm(struct drm_simple_display_pipe *pipe)
+{
+	return container_of(pipe, struct tinydrm_device, pipe);
+}
+
+/**
+ * TINYDRM_GEM_DRIVER_OPS - default tinydrm gem operations
+ *
+ * This macro provides a shortcut for setting the tinydrm GEM operations in
+ * the &drm_driver structure.
+ */
+#define TINYDRM_GEM_DRIVER_OPS \
+	.gem_free_object	= tinydrm_gem_cma_free_object, \
+	.gem_vm_ops		= &drm_gem_cma_vm_ops, \
+	.prime_handle_to_fd	= drm_gem_prime_handle_to_fd, \
+	.prime_fd_to_handle	= drm_gem_prime_fd_to_handle, \
+	.gem_prime_import	= drm_gem_prime_import, \
+	.gem_prime_export	= drm_gem_prime_export, \
+	.gem_prime_get_sg_table	= drm_gem_cma_prime_get_sg_table, \
+	.gem_prime_import_sg_table = tinydrm_gem_cma_prime_import_sg_table, \
+	.gem_prime_vmap		= drm_gem_cma_prime_vmap, \
+	.gem_prime_vunmap	= drm_gem_cma_prime_vunmap, \
+	.gem_prime_mmap		= drm_gem_cma_prime_mmap, \
+	.dumb_create		= drm_gem_cma_dumb_create, \
+	.dumb_map_offset	= drm_gem_cma_dumb_map_offset, \
+	.dumb_destroy		= drm_gem_dumb_destroy, \
+	.fops			= &tinydrm_fops
+
+/**
+ * TINYDRM_MODE - tinydrm display mode
+ * @hd: Horizontal resolution, width
+ * @vd: Vertical resolution, height
+ * @hd_mm: Display width in millimeters
+ * @vd_mm: Display height in millimeters
+ *
+ * This macro creates a &drm_display_mode for use with tinydrm.
+ */
+#define TINYDRM_MODE(hd, vd, hd_mm, vd_mm) \
+	.hdisplay = (hd), \
+	.hsync_start = (hd), \
+	.hsync_end = (hd), \
+	.htotal = (hd), \
+	.vdisplay = (vd), \
+	.vsync_start = (vd), \
+	.vsync_end = (vd), \
+	.vtotal = (vd), \
+	.width_mm = (hd_mm), \
+	.height_mm = (vd_mm), \
+	.type = DRM_MODE_TYPE_DRIVER, \
+	.clock = 1 /* pass validation */
+
+extern const struct file_operations tinydrm_fops;
+void tinydrm_lastclose(struct drm_device *drm);
+void tinydrm_gem_cma_free_object(struct drm_gem_object *gem_obj);
+struct drm_gem_object *
+tinydrm_gem_cma_prime_import_sg_table(struct drm_device *drm,
+				      struct dma_buf_attachment *attach,
+				      struct sg_table *sgt);
+int devm_tinydrm_init(struct device *parent, struct tinydrm_device *tdev,
+		      const struct drm_framebuffer_funcs *fb_funcs,
+		      struct drm_driver *driver);
+int devm_tinydrm_register(struct tinydrm_device *tdev);
+void tinydrm_shutdown(struct tinydrm_device *tdev);
+int tinydrm_suspend(struct tinydrm_device *tdev);
+int tinydrm_resume(struct tinydrm_device *tdev);
+
+void tinydrm_display_pipe_update(struct drm_simple_display_pipe *pipe,
+				 struct drm_plane_state *old_state);
+int tinydrm_display_pipe_prepare_fb(struct drm_simple_display_pipe *pipe,
+				    struct drm_plane_state *plane_state);
+int
+tinydrm_display_pipe_init(struct tinydrm_device *tdev,
+			  const struct drm_simple_display_pipe_funcs *funcs,
+			  int connector_type,
+			  const uint32_t *formats,
+			  unsigned int format_count,
+			  const struct drm_display_mode *mode,
+			  unsigned int rotation);
+
+#endif /* __LINUX_TINYDRM_H */