drm: Add helper for simple display pipeline

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

Changes since v4:
- Remove drm_connector_register() call
- Forgot to assign pipe->connector

Changes since v3:
- (struct drm_simple_display_pipe *)->funcs should be const

Changes since v2:
- Drop Kconfig knob DRM_KMS_HELPER
- Expand documentation

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()

Cc: jsarha@ti.com
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1465570559-14238-1-git-send-email-noralf@tronnes.org

4 files changed, 307 insertions, 1 deletions

diff --git a/Documentation/DocBook/gpu.tmpl b/Documentation/DocBook/gpu.tmpl
index 89585ad69a4b..d09536c91717 100644
--- a/Documentation/DocBook/gpu.tmpl
+++ b/Documentation/DocBook/gpu.tmpl
@@ -1688,6 +1688,12 @@ 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/Makefile b/drivers/gpu/drm/Makefile
index aa24af35c068..e3dba6f44a79 100644
--- a/drivers/gpu/drm/Makefile
+++ b/drivers/gpu/drm/Makefile
@@ -23,7 +23,8 @@ drm-$(CONFIG_AGP) += drm_agpsupport.o
 
 drm_kms_helper-y := drm_crtc_helper.o drm_dp_helper.o drm_probe_helper.o \
                 drm_plane_helper.o drm_dp_mst_topology.o drm_atomic_helper.o \
-                drm_kms_helper_common.o drm_dp_dual_mode_helper.o
+                drm_kms_helper_common.o drm_dp_dual_mode_helper.o \
+                drm_simple_kms_helper.o
 
 drm_kms_helper-$(CONFIG_DRM_LOAD_EDID_FIRMWARE) += drm_edid_load.o
 drm_kms_helper-$(CONFIG_DRM_FBDEV_EMULATION) += drm_fb_helper.o
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 000000000000..b2071d495ada
--- /dev/null
+++ b/drivers/gpu/drm/drm_simple_kms_helper.c
@@ -0,0 +1,205 @@
+/*
+ * 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/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 drivers for simple display
+ * hardware.
+ *
+ * drm_simple_display_pipe_init() initializes a simple display pipeline
+ * which has only one full-screen scanout buffer feeding one output. The
+ * pipeline is represented by struct &drm_simple_display_pipe and binds
+ * together &drm_plane, &drm_crtc and &drm_encoder structures into one fixed
+ * entity. Some flexibility for code reuse is provided through a separately
+ * allocated &drm_connector object and supporting optional &drm_bridge
+ * encoder drivers.
+ */
+
+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.
+ * Teardown of a simple display pipe is all handled automatically by the drm
+ * core through calling drm_mode_config_cleanup(). Drivers afterwards need to
+ * release the memory for the structure themselves.
+ *
+ * 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,
+                        const 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->connector = connector;
+        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;
+
+        return drm_mode_connector_attach_encoder(connector, encoder);
+}
+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 000000000000..269039722f91
--- /dev/null
+++ b/include/drm/drm_simple_kms_helper.h
@@ -0,0 +1,94 @@
+/*
+ * 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_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.
+         * The simple display pipeline helpers already check that the plane is
+         * not scaled, fills the entire visible area and is always enabled
+         * when the crtc is also enabled.
+         * 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. It should be initialized by calling drm_simple_display_pipe_init().
+ */
+struct drm_simple_display_pipe {
+        struct drm_crtc crtc;
+        struct drm_plane plane;
+        struct drm_encoder encoder;
+        struct drm_connector *connector;
+
+        const struct drm_simple_display_pipe_funcs *funcs;
+};
+
+int drm_simple_display_pipe_init(struct drm_device *dev,
+                        struct drm_simple_display_pipe *pipe,
+                        const 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 */