drm: rcar-du: Add writeback support for R-Car Gen3

Implement writeback support for R-Car Gen3 by exposing writeback
connectors. Behind the scene the calls are forwarded to the VSP
backend.

Using writeback connectors will allow implemented writeback support for
R-Car Gen2 with a consistent API if desired.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>

1 files changed, 243 insertions, 0 deletions

diff --git a/drivers/gpu/drm/rcar-du/rcar_du_writeback.c b/drivers/gpu/drm/rcar-du/rcar_du_writeback.c
new file mode 100644
index 000000000000..989a0be94131
--- /dev/null
+++ b/drivers/gpu/drm/rcar-du/rcar_du_writeback.c
@@ -0,0 +1,243 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * rcar_du_writeback.c  --  R-Car Display Unit Writeback Support
+ *
+ * Copyright (C) 2019 Laurent Pinchart <laurent.pinchart@ideasonboard.com>
+ */
+
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_device.h>
+#include <drm/drm_fourcc.h>
+#include <drm/drm_probe_helper.h>
+#include <drm/drm_writeback.h>
+
+#include "rcar_du_crtc.h"
+#include "rcar_du_drv.h"
+#include "rcar_du_kms.h"
+
+/**
+ * struct rcar_du_wb_conn_state - Driver-specific writeback connector state
+ * @state: base DRM connector state
+ * @format: format of the writeback framebuffer
+ */
+struct rcar_du_wb_conn_state {
+	struct drm_connector_state state;
+	const struct rcar_du_format_info *format;
+};
+
+#define to_rcar_wb_conn_state(s) \
+	container_of(s, struct rcar_du_wb_conn_state, state)
+
+/**
+ * struct rcar_du_wb_job - Driver-private data for writeback jobs
+ * @sg_tables: scatter-gather tables for the framebuffer memory
+ */
+struct rcar_du_wb_job {
+	struct sg_table sg_tables[3];
+};
+
+static int rcar_du_wb_conn_get_modes(struct drm_connector *connector)
+{
+	struct drm_device *dev = connector->dev;
+
+	return drm_add_modes_noedid(connector, dev->mode_config.max_width,
+				    dev->mode_config.max_height);
+}
+
+static int rcar_du_wb_prepare_job(struct drm_writeback_connector *connector,
+				  struct drm_writeback_job *job)
+{
+	struct rcar_du_crtc *rcrtc = wb_to_rcar_crtc(connector);
+	struct rcar_du_wb_job *rjob;
+	int ret;
+
+	if (!job->fb)
+		return 0;
+
+	rjob = kzalloc(sizeof(*rjob), GFP_KERNEL);
+	if (!rjob)
+		return -ENOMEM;
+
+	/* Map the framebuffer to the VSP. */
+	ret = rcar_du_vsp_map_fb(rcrtc->vsp, job->fb, rjob->sg_tables);
+	if (ret < 0) {
+		kfree(rjob);
+		return ret;
+	}
+
+	job->priv = rjob;
+	return 0;
+}
+
+static void rcar_du_wb_cleanup_job(struct drm_writeback_connector *connector,
+				   struct drm_writeback_job *job)
+{
+	struct rcar_du_crtc *rcrtc = wb_to_rcar_crtc(connector);
+	struct rcar_du_wb_job *rjob = job->priv;
+
+	if (!job->fb)
+		return;
+
+	rcar_du_vsp_unmap_fb(rcrtc->vsp, job->fb, rjob->sg_tables);
+	kfree(rjob);
+}
+
+static const struct drm_connector_helper_funcs rcar_du_wb_conn_helper_funcs = {
+	.get_modes = rcar_du_wb_conn_get_modes,
+	.prepare_writeback_job = rcar_du_wb_prepare_job,
+	.cleanup_writeback_job = rcar_du_wb_cleanup_job,
+};
+
+static struct drm_connector_state *
+rcar_du_wb_conn_duplicate_state(struct drm_connector *connector)
+{
+	struct rcar_du_wb_conn_state *copy;
+
+	if (WARN_ON(!connector->state))
+		return NULL;
+
+	copy = kzalloc(sizeof(*copy), GFP_KERNEL);
+	if (!copy)
+		return NULL;
+
+	__drm_atomic_helper_connector_duplicate_state(connector, &copy->state);
+
+	return &copy->state;
+}
+
+static void rcar_du_wb_conn_destroy_state(struct drm_connector *connector,
+					  struct drm_connector_state *state)
+{
+	__drm_atomic_helper_connector_destroy_state(state);
+	kfree(to_rcar_wb_conn_state(state));
+}
+
+static void rcar_du_wb_conn_reset(struct drm_connector *connector)
+{
+	struct rcar_du_wb_conn_state *state;
+
+	if (connector->state) {
+		rcar_du_wb_conn_destroy_state(connector, connector->state);
+		connector->state = NULL;
+	}
+
+	state = kzalloc(sizeof(*state), GFP_KERNEL);
+	if (state == NULL)
+		return;
+
+	__drm_atomic_helper_connector_reset(connector, &state->state);
+}
+
+static const struct drm_connector_funcs rcar_du_wb_conn_funcs = {
+	.reset = rcar_du_wb_conn_reset,
+	.fill_modes = drm_helper_probe_single_connector_modes,
+	.destroy = drm_connector_cleanup,
+	.atomic_duplicate_state = rcar_du_wb_conn_duplicate_state,
+	.atomic_destroy_state = rcar_du_wb_conn_destroy_state,
+};
+
+static int rcar_du_wb_enc_atomic_check(struct drm_encoder *encoder,
+				       struct drm_crtc_state *crtc_state,
+				       struct drm_connector_state *conn_state)
+{
+	struct rcar_du_wb_conn_state *wb_state =
+		to_rcar_wb_conn_state(conn_state);
+	const struct drm_display_mode *mode = &crtc_state->mode;
+	struct drm_device *dev = encoder->dev;
+	struct drm_framebuffer *fb;
+
+	if (!conn_state->writeback_job || !conn_state->writeback_job->fb)
+		return 0;
+
+	fb = conn_state->writeback_job->fb;
+
+	/*
+	 * Verify that the framebuffer format is supported and that its size
+	 * matches the current mode.
+	 */
+	if (fb->width != mode->hdisplay || fb->height != mode->vdisplay) {
+		dev_dbg(dev->dev, "%s: invalid framebuffer size %ux%u\n",
+			__func__, fb->width, fb->height);
+		return -EINVAL;
+	}
+
+	wb_state->format = rcar_du_format_info(fb->format->format);
+	if (wb_state->format == NULL) {
+		dev_dbg(dev->dev, "%s: unsupported format %08x\n", __func__,
+			fb->format->format);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static const struct drm_encoder_helper_funcs rcar_du_wb_enc_helper_funcs = {
+	.atomic_check = rcar_du_wb_enc_atomic_check,
+};
+
+/*
+ * Only RGB formats are currently supported as the VSP outputs RGB to the DU
+ * and can't convert to YUV separately for writeback.
+ */
+static const u32 writeback_formats[] = {
+	DRM_FORMAT_RGB332,
+	DRM_FORMAT_ARGB4444,
+	DRM_FORMAT_XRGB4444,
+	DRM_FORMAT_ARGB1555,
+	DRM_FORMAT_XRGB1555,
+	DRM_FORMAT_RGB565,
+	DRM_FORMAT_BGR888,
+	DRM_FORMAT_RGB888,
+	DRM_FORMAT_BGRA8888,
+	DRM_FORMAT_BGRX8888,
+	DRM_FORMAT_ARGB8888,
+	DRM_FORMAT_XRGB8888,
+};
+
+int rcar_du_writeback_init(struct rcar_du_device *rcdu,
+			   struct rcar_du_crtc *rcrtc)
+{
+	struct drm_writeback_connector *wb_conn = &rcrtc->writeback;
+
+	wb_conn->encoder.possible_crtcs = 1 << drm_crtc_index(&rcrtc->crtc);
+	drm_connector_helper_add(&wb_conn->base,
+				 &rcar_du_wb_conn_helper_funcs);
+
+	return drm_writeback_connector_init(rcdu->ddev, wb_conn,
+					    &rcar_du_wb_conn_funcs,
+					    &rcar_du_wb_enc_helper_funcs,
+					    writeback_formats,
+					    ARRAY_SIZE(writeback_formats));
+}
+
+void rcar_du_writeback_setup(struct rcar_du_crtc *rcrtc,
+			     struct vsp1_du_writeback_config *cfg)
+{
+	struct rcar_du_wb_conn_state *wb_state;
+	struct drm_connector_state *state;
+	struct rcar_du_wb_job *rjob;
+	struct drm_framebuffer *fb;
+	unsigned int i;
+
+	state = rcrtc->writeback.base.state;
+	if (!state || !state->writeback_job || !state->writeback_job->fb)
+		return;
+
+	fb = state->writeback_job->fb;
+	rjob = state->writeback_job->priv;
+	wb_state = to_rcar_wb_conn_state(state);
+
+	cfg->pixelformat = wb_state->format->v4l2;
+	cfg->pitch = fb->pitches[0];
+
+	for (i = 0; i < wb_state->format->planes; ++i)
+		cfg->mem[i] = sg_dma_address(rjob->sg_tables[i].sgl)
+			    + fb->offsets[i];
+
+	drm_writeback_queue_job(&rcrtc->writeback, state);
+}
+
+void rcar_du_writeback_complete(struct rcar_du_crtc *rcrtc)
+{
+	drm_writeback_signal_completion(&rcrtc->writeback, 0);
+}