drm: Add support for the LogiCVC display controller

Introduces a driver for the LogiCVC display controller, a programmable
logic controller optimized for use in Xilinx Zynq-7000 SoCs and other
Xilinx FPGAs. The controller is mostly configured at logic synthesis
time so only a subset of configuration is left for the driver to
handle.

The following features are implemented and tested:
- LVDS 4-bit interface;
- RGB565 pixel formats;
- Multiple layers and hardware composition;
- Layer-wide alpha mode;

The following features are implemented but untested:
- Other RGB pixel formats;
- Layer framebuffer configuration for version 4;
- Lowest-layer used as background color;
- Per-pixel alpha mode.

The following features are not implemented:
- YUV pixel formats;
- DVI, LVDS 3-bit, ITU656 and camera link interfaces;
- External parallel input for layer;
- Color-keying;
- LUT-based alpha modes.

Additional implementation-specific notes:
- Panels are only enabled after the first page flip to avoid flashing a
  white screen.
- Depth used in context of the LogiCVC driver only counts color components
  to match the definition of the synthesis parameters.

Support is implemented for both version 3 and 4 of the controller.

With version 3, framebuffers are stored in a dedicated contiguous
memory area, with a base address hardcoded for each layer. This requires
using a dedicated CMA pool registered at the base address and tweaking a
few offset-related registers to try to use any buffer allocated from
the pool. This is done on a best-effort basis to have the hardware cope
with the DRM framebuffer allocation model and there is no guarantee
that each buffer allocated by GEM CMA can be used for any layer.
In particular, buffers allocated below the base address for a layer are
guaranteed not to be configurable for that layer. See the implementation of
logicvc_layer_buffer_find_setup for specifics.

Version 4 allows configuring each buffer address directly, which
guarantees that any buffer can be configured.

Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Reviewed-by: Maxime Ripard <mripard@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220520141555.1429041-2-paul.kocialkowski@bootlin.com

1 files changed, 214 insertions, 0 deletions

diff --git a/drivers/gpu/drm/logicvc/logicvc_interface.c b/drivers/gpu/drm/logicvc/logicvc_interface.c
new file mode 100644
index 000000000000..c73592f6c406
--- /dev/null
+++ b/drivers/gpu/drm/logicvc/logicvc_interface.c
@@ -0,0 +1,214 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2019-2022 Bootlin
+ * Author: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
+ */
+
+#include <linux/types.h>
+
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_bridge.h>
+#include <drm/drm_connector.h>
+#include <drm/drm_crtc_helper.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_encoder.h>
+#include <drm/drm_gem_cma_helper.h>
+#include <drm/drm_modeset_helper_vtables.h>
+#include <drm/drm_of.h>
+#include <drm/drm_panel.h>
+#include <drm/drm_print.h>
+#include <drm/drm_probe_helper.h>
+
+#include "logicvc_crtc.h"
+#include "logicvc_drm.h"
+#include "logicvc_interface.h"
+#include "logicvc_regs.h"
+
+#define logicvc_interface_from_drm_encoder(c) \
+	container_of(c, struct logicvc_interface, drm_encoder)
+#define logicvc_interface_from_drm_connector(c) \
+	container_of(c, struct logicvc_interface, drm_connector)
+
+static void logicvc_encoder_enable(struct drm_encoder *drm_encoder)
+{
+	struct logicvc_drm *logicvc = logicvc_drm(drm_encoder->dev);
+	struct logicvc_interface *interface =
+		logicvc_interface_from_drm_encoder(drm_encoder);
+
+	regmap_update_bits(logicvc->regmap, LOGICVC_POWER_CTRL_REG,
+			   LOGICVC_POWER_CTRL_VIDEO_ENABLE,
+			   LOGICVC_POWER_CTRL_VIDEO_ENABLE);
+
+	if (interface->drm_panel) {
+		drm_panel_prepare(interface->drm_panel);
+		drm_panel_enable(interface->drm_panel);
+	}
+}
+
+static void logicvc_encoder_disable(struct drm_encoder *drm_encoder)
+{
+	struct logicvc_interface *interface =
+		logicvc_interface_from_drm_encoder(drm_encoder);
+
+	if (interface->drm_panel) {
+		drm_panel_disable(interface->drm_panel);
+		drm_panel_unprepare(interface->drm_panel);
+	}
+}
+
+static const struct drm_encoder_helper_funcs logicvc_encoder_helper_funcs = {
+	.enable			= logicvc_encoder_enable,
+	.disable		= logicvc_encoder_disable,
+};
+
+static const struct drm_encoder_funcs logicvc_encoder_funcs = {
+	.destroy		= drm_encoder_cleanup,
+};
+
+static int logicvc_connector_get_modes(struct drm_connector *drm_connector)
+{
+	struct logicvc_interface *interface =
+		logicvc_interface_from_drm_connector(drm_connector);
+
+	if (interface->drm_panel)
+		return drm_panel_get_modes(interface->drm_panel, drm_connector);
+
+	WARN_ONCE(1, "Retrieving modes from a native connector is not implemented.");
+
+	return 0;
+}
+
+static const struct drm_connector_helper_funcs logicvc_connector_helper_funcs = {
+	.get_modes		= logicvc_connector_get_modes,
+};
+
+static const struct drm_connector_funcs logicvc_connector_funcs = {
+	.reset			= drm_atomic_helper_connector_reset,
+	.fill_modes		= drm_helper_probe_single_connector_modes,
+	.destroy		= drm_connector_cleanup,
+	.atomic_duplicate_state	= drm_atomic_helper_connector_duplicate_state,
+	.atomic_destroy_state	= drm_atomic_helper_connector_destroy_state,
+};
+
+static int logicvc_interface_encoder_type(struct logicvc_drm *logicvc)
+{
+	switch (logicvc->config.display_interface) {
+	case LOGICVC_DISPLAY_INTERFACE_LVDS_4BITS:
+	case LOGICVC_DISPLAY_INTERFACE_LVDS_4BITS_CAMERA:
+	case LOGICVC_DISPLAY_INTERFACE_LVDS_3BITS:
+		return DRM_MODE_ENCODER_LVDS;
+	case LOGICVC_DISPLAY_INTERFACE_DVI:
+		return DRM_MODE_ENCODER_TMDS;
+	case LOGICVC_DISPLAY_INTERFACE_RGB:
+		return DRM_MODE_ENCODER_DPI;
+	default:
+		return DRM_MODE_ENCODER_NONE;
+	}
+}
+
+static int logicvc_interface_connector_type(struct logicvc_drm *logicvc)
+{
+	switch (logicvc->config.display_interface) {
+	case LOGICVC_DISPLAY_INTERFACE_LVDS_4BITS:
+	case LOGICVC_DISPLAY_INTERFACE_LVDS_4BITS_CAMERA:
+	case LOGICVC_DISPLAY_INTERFACE_LVDS_3BITS:
+		return DRM_MODE_CONNECTOR_LVDS;
+	case LOGICVC_DISPLAY_INTERFACE_DVI:
+		return DRM_MODE_CONNECTOR_DVID;
+	case LOGICVC_DISPLAY_INTERFACE_RGB:
+		return DRM_MODE_CONNECTOR_DPI;
+	default:
+		return DRM_MODE_CONNECTOR_Unknown;
+	}
+}
+
+static bool logicvc_interface_native_connector(struct logicvc_drm *logicvc)
+{
+	switch (logicvc->config.display_interface) {
+	case LOGICVC_DISPLAY_INTERFACE_DVI:
+		return true;
+	default:
+		return false;
+	}
+}
+
+void logicvc_interface_attach_crtc(struct logicvc_drm *logicvc)
+{
+	uint32_t possible_crtcs = drm_crtc_mask(&logicvc->crtc->drm_crtc);
+
+	logicvc->interface->drm_encoder.possible_crtcs = possible_crtcs;
+}
+
+int logicvc_interface_init(struct logicvc_drm *logicvc)
+{
+	struct logicvc_interface *interface;
+	struct drm_device *drm_dev = &logicvc->drm_dev;
+	struct device *dev = drm_dev->dev;
+	struct device_node *of_node = dev->of_node;
+	int encoder_type = logicvc_interface_encoder_type(logicvc);
+	int connector_type = logicvc_interface_connector_type(logicvc);
+	bool native_connector = logicvc_interface_native_connector(logicvc);
+	int ret;
+
+	interface = devm_kzalloc(dev, sizeof(*interface), GFP_KERNEL);
+	if (!interface) {
+		ret = -ENOMEM;
+		goto error_early;
+	}
+
+	ret = drm_of_find_panel_or_bridge(of_node, 0, 0, &interface->drm_panel,
+					  &interface->drm_bridge);
+	if (ret == -EPROBE_DEFER)
+		goto error_early;
+
+	ret = drm_encoder_init(drm_dev, &interface->drm_encoder,
+			       &logicvc_encoder_funcs, encoder_type, NULL);
+	if (ret) {
+		drm_err(drm_dev, "Failed to initialize encoder\n");
+		goto error_early;
+	}
+
+	drm_encoder_helper_add(&interface->drm_encoder,
+			       &logicvc_encoder_helper_funcs);
+
+	if (native_connector || interface->drm_panel) {
+		ret = drm_connector_init(drm_dev, &interface->drm_connector,
+					 &logicvc_connector_funcs,
+					 connector_type);
+		if (ret) {
+			drm_err(drm_dev, "Failed to initialize connector\n");
+			goto error_encoder;
+		}
+
+		drm_connector_helper_add(&interface->drm_connector,
+					 &logicvc_connector_helper_funcs);
+
+		ret = drm_connector_attach_encoder(&interface->drm_connector,
+						   &interface->drm_encoder);
+		if (ret) {
+			drm_err(drm_dev,
+				"Failed to attach connector to encoder\n");
+			goto error_encoder;
+		}
+	}
+
+	if (interface->drm_bridge) {
+		ret = drm_bridge_attach(&interface->drm_encoder,
+					interface->drm_bridge, NULL, 0);
+		if (ret) {
+			drm_err(drm_dev,
+				"Failed to attach bridge to encoder\n");
+			goto error_encoder;
+		}
+	}
+
+	logicvc->interface = interface;
+
+	return 0;
+
+error_encoder:
+	drm_encoder_cleanup(&interface->drm_encoder);
+
+error_early:
+	return ret;
+}