[PATCH v2 6/6] drm: Add helper for simple display pipeline

[Noralf TrÃnnes]

Provides helper functions for drivers that have a simple display
pipeline. Plane, crtc and encoder are collapsed into one entity.

Signed-off-by: Noralf TrÃnnes <noralf@xxxxxxxxxxx>
---

Changes since v1:
- Add DOC header and add to gpu.tmpl
- Fix docs: @funcs is optional, "negative error code",
  "This hook is optional."
- Add checks to drm_simple_kms_plane_atomic_check()

 Documentation/DocBook/gpu.tmpl          |   6 +
 drivers/gpu/drm/Kconfig                 |   7 ++
 drivers/gpu/drm/Makefile                |   1 +
 drivers/gpu/drm/drm_simple_kms_helper.c | 200 ++++++++++++++++++++++++++++++++
 include/drm/drm_simple_kms_helper.h     |  92 +++++++++++++++
 5 files changed, 306 insertions(+)
 create mode 100644 drivers/gpu/drm/drm_simple_kms_helper.c
 create mode 100644 include/drm/drm_simple_kms_helper.h

diff --git a/Documentation/DocBook/gpu.tmpl b/Documentation/DocBook/gpu.tmpl
index 4a0c599..cf3f5a8 100644
--- a/Documentation/DocBook/gpu.tmpl
+++ b/Documentation/DocBook/gpu.tmpl
@@ -1693,6 +1693,12 @@ void intel_crt_init(struct drm_device *dev)
 !Edrivers/gpu/drm/drm_panel.c
 !Pdrivers/gpu/drm/drm_panel.c drm panel
     </sect2>
+    <sect2>
+      <title>Simple KMS Helper Reference</title>
+!Iinclude/drm/drm_simple_kms_helper.h
+!Edrivers/gpu/drm/drm_simple_kms_helper.c
+!Pdrivers/gpu/drm/drm_simple_kms_helper.c overview
+    </sect2>
   </sect1>

   <!-- Internals: kms properties -->
diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index 16e4c21..ff9f480 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -39,6 +39,13 @@ config DRM_KMS_HELPER
 	help
 	  CRTC helpers for KMS drivers.

+config DRM_SIMPLE_KMS_HELPER
+	tristate
+	depends on DRM
+	select DRM_KMS_HELPER
+	help
+	  Helpers for very simple KMS drivers.
+
 config DRM_KMS_FB_HELPER
 	bool
 	depends on DRM_KMS_HELPER
diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
index 43c2abf..7e99923 100644
--- a/drivers/gpu/drm/Makefile
+++ b/drivers/gpu/drm/Makefile
@@ -31,6 +31,7 @@ drm_kms_helper-$(CONFIG_DRM_KMS_CMA_HELPER) += drm_fb_cma_helper.o
 drm_kms_helper-$(CONFIG_DRM_DP_AUX_CHARDEV) += drm_dp_aux_dev.o

 obj-$(CONFIG_DRM_KMS_HELPER) += drm_kms_helper.o
+obj-$(CONFIG_DRM_SIMPLE_KMS_HELPER) += drm_simple_kms_helper.o

 CFLAGS_drm_trace_points.o := -I$(src)

diff --git a/drivers/gpu/drm/drm_simple_kms_helper.c b/drivers/gpu/drm/drm_simple_kms_helper.c
new file mode 100644
index 0000000..64bf0f2
--- /dev/null
+++ b/drivers/gpu/drm/drm_simple_kms_helper.c
@@ -0,0 +1,200 @@
+/*
+ * Copyright (C) 2016 Noralf TrÃnnes
+ *
+ * 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/drmP.h>
+#include <drm/drm_atomic.h>
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_crtc_helper.h>
+#include <drm/drm_plane_helper.h>
+#include <drm/drm_simple_kms_helper.h>
+#include <linux/slab.h>
+
+/**
+ * DOC: overview
+ *
+ * This helper library provides helpers for simple drivers.
+ *
+ * drm_simple_display_pipe_init() initializes a simple display pipeline
+ * consisting of a plane-crtc-encoder pipe coupled with a connector.
+ */
+
+static const struct drm_encoder_funcs drm_simple_kms_encoder_funcs = {
+	.destroy = drm_encoder_cleanup,
+};
+
+static void drm_simple_kms_crtc_enable(struct drm_crtc *crtc)
+{
+	struct drm_simple_display_pipe *pipe;
+
+	pipe = container_of(crtc, struct drm_simple_display_pipe, crtc);
+	if (!pipe->funcs || !pipe->funcs->enable)
+		return;
+
+	pipe->funcs->enable(pipe, crtc->state);
+}
+
+static void drm_simple_kms_crtc_disable(struct drm_crtc *crtc)
+{
+	struct drm_simple_display_pipe *pipe;
+
+	pipe = container_of(crtc, struct drm_simple_display_pipe, crtc);
+	if (!pipe->funcs || !pipe->funcs->disable)
+		return;
+
+	pipe->funcs->disable(pipe);
+}
+
+static const struct drm_crtc_helper_funcs drm_simple_kms_crtc_helper_funcs = {
+	.disable = drm_simple_kms_crtc_disable,
+	.enable = drm_simple_kms_crtc_enable,
+};
+
+static const struct drm_crtc_funcs drm_simple_kms_crtc_funcs = {
+	.reset = drm_atomic_helper_crtc_reset,
+	.destroy = drm_crtc_cleanup,
+	.set_config = drm_atomic_helper_set_config,
+	.page_flip = drm_atomic_helper_page_flip,
+	.atomic_duplicate_state = drm_atomic_helper_crtc_duplicate_state,
+	.atomic_destroy_state = drm_atomic_helper_crtc_destroy_state,
+};
+
+static int drm_simple_kms_plane_atomic_check(struct drm_plane *plane,
+					struct drm_plane_state *plane_state)
+{
+	struct drm_rect src = {
+		.x1 = plane_state->src_x,
+		.y1 = plane_state->src_y,
+		.x2 = plane_state->src_x + plane_state->src_w,
+		.y2 = plane_state->src_y + plane_state->src_h,
+	};
+	struct drm_rect dest = {
+		.x1 = plane_state->crtc_x,
+		.y1 = plane_state->crtc_y,
+		.x2 = plane_state->crtc_x + plane_state->crtc_w,
+		.y2 = plane_state->crtc_y + plane_state->crtc_h,
+	};
+	struct drm_rect clip = { 0 };
+	struct drm_simple_display_pipe *pipe;
+	struct drm_crtc_state *crtc_state;
+	bool visible;
+	int ret;
+
+	pipe = container_of(plane, struct drm_simple_display_pipe, plane);
+	crtc_state = drm_atomic_get_existing_crtc_state(plane_state->state,
+							&pipe->crtc);
+	if (crtc_state->enable != !!plane_state->crtc)
+		return -EINVAL; /* plane must match crtc enable state */
+
+	if (!crtc_state->enable)
+		return 0; /* nothing to check when disabling or disabled */
+
+	clip.x2 = crtc_state->adjusted_mode.hdisplay;
+	clip.y2 = crtc_state->adjusted_mode.vdisplay;
+	ret = drm_plane_helper_check_update(plane, &pipe->crtc,
+					    plane_state->fb,
+					    &src, &dest, &clip,
+					    DRM_PLANE_HELPER_NO_SCALING,
+					    DRM_PLANE_HELPER_NO_SCALING,
+					    false, true, &visible);
+	if (ret)
+		return ret;
+
+	if (!visible)
+		return -EINVAL;
+
+	if (!pipe->funcs || !pipe->funcs->check)
+		return 0;
+
+	return pipe->funcs->check(pipe, plane_state, crtc_state);
+}
+
+static void drm_simple_kms_plane_atomic_update(struct drm_plane *plane,
+					struct drm_plane_state *pstate)
+{
+	struct drm_simple_display_pipe *pipe;
+
+	pipe = container_of(plane, struct drm_simple_display_pipe, plane);
+	if (!pipe->funcs || !pipe->funcs->update)
+		return;
+
+	pipe->funcs->update(pipe, pstate);
+}
+
+static const struct drm_plane_helper_funcs drm_simple_kms_plane_helper_funcs = {
+	.atomic_check = drm_simple_kms_plane_atomic_check,
+	.atomic_update = drm_simple_kms_plane_atomic_update,
+};
+
+static const struct drm_plane_funcs drm_simple_kms_plane_funcs = {
+	.update_plane		= drm_atomic_helper_update_plane,
+	.disable_plane		= drm_atomic_helper_disable_plane,
+	.destroy		= drm_plane_cleanup,
+	.reset			= drm_atomic_helper_plane_reset,
+	.atomic_duplicate_state	= drm_atomic_helper_plane_duplicate_state,
+	.atomic_destroy_state	= drm_atomic_helper_plane_destroy_state,
+};
+
+/**
+ * drm_simple_display_pipe_init - Initialize a simple display pipeline
+ * @dev: DRM device
+ * @pipe: simple display pipe object to initialize
+ * @funcs: callbacks for the display pipe (optional)
+ * @formats: array of supported formats (%DRM_FORMAT_*)
+ * @format_count: number of elements in @formats
+ * @connector: connector to attach and register
+ *
+ * Sets up a display pipeline which consist of a really simple
+ * plane-crtc-encoder pipe coupled with the provided connector.
+ *
+ * Returns:
+ * Zero on success, negative error code on failure.
+ */
+int drm_simple_display_pipe_init(struct drm_device *dev,
+				 struct drm_simple_display_pipe *pipe,
+				 struct drm_simple_display_pipe_funcs *funcs,
+				 const uint32_t *formats,
+				 unsigned int format_count,
+				 struct drm_connector *connector)
+{
+	struct drm_encoder *encoder = &pipe->encoder;
+	struct drm_plane *plane = &pipe->plane;
+	struct drm_crtc *crtc = &pipe->crtc;
+	int ret;
+
+	pipe->funcs = funcs;
+
+	drm_plane_helper_add(plane, &drm_simple_kms_plane_helper_funcs);
+	ret = drm_universal_plane_init(dev, plane, 0,
+				       &drm_simple_kms_plane_funcs,
+				       formats, format_count,
+				       DRM_PLANE_TYPE_PRIMARY, NULL);
+	if (ret)
+		return ret;
+
+	drm_crtc_helper_add(crtc, &drm_simple_kms_crtc_helper_funcs);
+	ret = drm_crtc_init_with_planes(dev, crtc, plane, NULL,
+					&drm_simple_kms_crtc_funcs, NULL);
+	if (ret)
+		return ret;
+
+	encoder->possible_crtcs = 1 << drm_crtc_index(crtc);
+	ret = drm_encoder_init(dev, encoder, &drm_simple_kms_encoder_funcs,
+			       DRM_MODE_ENCODER_NONE, NULL);
+	if (ret)
+		return ret;
+
+	ret = drm_mode_connector_attach_encoder(connector, encoder);
+	if (ret)
+		return ret;
+
+	return drm_connector_register(connector);
+}
+EXPORT_SYMBOL(drm_simple_display_pipe_init);
+
+MODULE_LICENSE("GPL");
diff --git a/include/drm/drm_simple_kms_helper.h b/include/drm/drm_simple_kms_helper.h
new file mode 100644
index 0000000..ef578f4
--- /dev/null
+++ b/include/drm/drm_simple_kms_helper.h
@@ -0,0 +1,92 @@
+/*
+ * Copyright (C) 2016 Noralf TrÃnnes
+ *
+ * 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_DRM_SIMPLE_KMS_HELPER_H
+#define __LINUX_DRM_SIMPLE_KMS_HELPER_H
+
+struct drm_simple_display_pipe;
+
+/**
+ * struct drm_simple_display_pipe_funcs - helper operations for a simple
+ *                                        display pipeline
+ */
+struct drm_simple_display_pipe_funcs {
+	/**
+	 * @enable:
+	 *
+	 * This function should be used to enable the pipeline.
+	 * It is called when the underlying crtc is enabled.
+	 * This hook is optional.
+	 */
+	void (*enable)(struct drm_simple_display_pipe *pipe,
+		       struct drm_crtc_state *crtc_state);
+	/**
+	 * @disable:
+	 *
+	 * This function should be used to disable the pipeline.
+	 * It is called when the underlying crtc is disabled.
+	 * This hook is optional.
+	 */
+	void (*disable)(struct drm_simple_display_pipe *pipe);
+
+	/**
+	 * @check:
+	 *
+	 * This function is called in the check phase of an atomic update,
+	 * specifically when the underlying plane is checked.
+	 * This hook is optional.
+	 *
+	 * RETURNS:
+	 *
+	 * 0 on success, -EINVAL if the state or the transition can't be
+	 * supported, -ENOMEM on memory allocation failure and -EDEADLK if an
+	 * attempt to obtain another state object ran into a &drm_modeset_lock
+	 * deadlock.
+	 */
+	int (*check)(struct drm_simple_display_pipe *pipe,
+		     struct drm_plane_state *plane_state,
+		     struct drm_crtc_state *crtc_state);
+	/**
+	 * @update:
+	 *
+	 * This function is called when the underlying plane state is updated.
+	 * This hook is optional.
+	 */
+	void (*update)(struct drm_simple_display_pipe *pipe,
+		       struct drm_plane_state *plane_state);
+};
+
+/**
+ * struct drm_simple_display_pipe - simple display pipeline
+ * @crtc: CRTC control structure
+ * @plane: Plane control structure
+ * @encoder: Encoder control structure
+ * @connector: Connector control structure
+ * @funcs: Pipeline control functions (optional)
+ *
+ * Simple display pipeline with plane, crtc and encoder collapsed into one
+ * entity.
+ */
+struct drm_simple_display_pipe {
+	struct drm_crtc crtc;
+	struct drm_plane plane;
+	struct drm_encoder encoder;
+	struct drm_connector *connector;
+
+	struct drm_simple_display_pipe_funcs *funcs;
+};
+
+int drm_simple_display_pipe_init(struct drm_device *dev,
+				 struct drm_simple_display_pipe *pipe,
+				 struct drm_simple_display_pipe_funcs *funcs,
+				 const uint32_t *formats,
+				 unsigned int format_count,
+				 struct drm_connector *connector);
+
+#endif /* __LINUX_DRM_SIMPLE_KMS_HELPER_H */
--
2.8.2