drm/vc4: Add DPI driver

The DPI interface involves taking a ton of our GPIOs to be used as
outputs, and routing display signals over them in parallel.

v2: Use display_info.bus_formats[] to replace our custom DT
    properties.
v3: Rebase on V3D documentation changes.
v4: Fix rebase detritus from V3D documentation changes.
Signed-off-by: Eric Anholt <eric@anholt.net>
Acked-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/display/brcm,bcm-vc4.txt

@@ -35,12 +35,22 @@ Optional properties for HDMI:
 		  as an interrupt/status bit in the HDMI controller
 		  itself).  See bindings/pinctrl/brcm,bcm2835-gpio.txt
 
+Required properties for DPI:
+- compatible:	Should be "brcm,bcm2835-dpi"
+- reg:		Physical base address and length of the registers
+- clocks:	a) core: The core clock the unit runs on
+		b) pixel: The pixel clock that feeds the pixelvalve
+- port:		Port node with a single endpoint connecting to the panel
+		  device, as defined in [1]
+
 Required properties for V3D:
 - compatible:	Should be "brcm,bcm2835-v3d"
 - reg:		Physical base address and length of the V3D's registers
 - interrupts:	The interrupt number
 		  See bindings/interrupt-controller/brcm,bcm2835-armctrl-ic.txt
 
+[1] Documentation/devicetree/bindings/media/video-interfaces.txt
+
 Example:
 pixelvalve@7e807000 {
 	compatible = "brcm,bcm2835-pixelvalve2";
@@ -66,6 +76,22 @@ hdmi: hdmi@7e902000 {
 	clock-names = "pixel", "hdmi";
 };
 
+dpi: dpi@7e208000 {
+	compatible = "brcm,bcm2835-dpi";
+	reg = <0x7e208000 0x8c>;
+	clocks = <&clocks BCM2835_CLOCK_VPU>,
+	         <&clocks BCM2835_CLOCK_DPI>;
+	clock-names = "core", "pixel";
+	#address-cells = <1>;
+	#size-cells = <0>;
+
+	port {
+		dpi_out: endpoint@0 {
+			remote-endpoint = <&panel_in>;
+		};
+	};
+};
+
 v3d: v3d@7ec00000 {
 	compatible = "brcm,bcm2835-v3d";
 	reg = <0x7ec00000 0x1000>;
@@ -75,3 +101,13 @@ v3d: v3d@7ec00000 {
 vc4: gpu {
 	compatible = "brcm,bcm2835-vc4";
 };
+
+panel: panel {
+	compatible = "ontat,yx700wv03", "simple-panel";
+
+	port {
+		panel_in: endpoint {
+			remote-endpoint = <&dpi_out>;
+		};
+	};
+};

drivers/gpu/drm/vc4/Kconfig

@@ -5,6 +5,7 @@ config DRM_VC4
 	select DRM_KMS_HELPER
 	select DRM_KMS_CMA_HELPER
 	select DRM_GEM_CMA_HELPER
+	select DRM_PANEL
 	help
 	  Choose this option if you have a system that has a Broadcom
 	  VC4 GPU, such as the Raspberry Pi or other BCM2708/BCM2835.

drivers/gpu/drm/vc4/Makefile

@@ -7,6 +7,7 @@ vc4-y := \
 	vc4_bo.o \
 	vc4_crtc.o \
 	vc4_drv.o \
+	vc4_dpi.o \
 	vc4_kms.o \
 	vc4_gem.o \
 	vc4_hdmi.o \

drivers/gpu/drm/vc4/vc4_debugfs.c

@@ -17,6 +17,7 @@
 
 static const struct drm_info_list vc4_debugfs_list[] = {
 	{"bo_stats", vc4_bo_stats_debugfs, 0},
+	{"dpi_regs", vc4_dpi_debugfs_regs, 0},
 	{"hdmi_regs", vc4_hdmi_debugfs_regs, 0},
 	{"hvs_regs", vc4_hvs_debugfs_regs, 0},
 	{"crtc0_regs", vc4_crtc_debugfs_regs, 0, (void *)(uintptr_t)0},

drivers/gpu/drm/vc4/vc4_dpi.c

+/*
+ * Copyright (C) 2016 Broadcom Limited
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/**
+ * DOC: VC4 DPI module
+ *
+ * The VC4 DPI hardware supports MIPI DPI type 4 and Nokia ViSSI
+ * signals, which are routed out to GPIO0-27 with the ALT2 function.
+ */
+
+#include "drm_atomic_helper.h"
+#include "drm_crtc_helper.h"
+#include "drm_edid.h"
+#include "drm_panel.h"
+#include "linux/clk.h"
+#include "linux/component.h"
+#include "linux/of_graph.h"
+#include "linux/of_platform.h"
+#include "vc4_drv.h"
+#include "vc4_regs.h"
+
+#define DPI_C			0x00
+# define DPI_OUTPUT_ENABLE_MODE		BIT(16)
+
+/* The order field takes the incoming 24 bit RGB from the pixel valve
+ * and shuffles the 3 channels.
+ */
+# define DPI_ORDER_MASK			VC4_MASK(15, 14)
+# define DPI_ORDER_SHIFT		14
+# define DPI_ORDER_RGB			0
+# define DPI_ORDER_BGR			1
+# define DPI_ORDER_GRB			2
+# define DPI_ORDER_BRG			3
+
+/* The format field takes the ORDER-shuffled pixel valve data and
+ * formats it onto the output lines.
+ */
+# define DPI_FORMAT_MASK		VC4_MASK(13, 11)
+# define DPI_FORMAT_SHIFT		11
+/* This define is named in the hardware, but actually just outputs 0. */
+# define DPI_FORMAT_9BIT_666_RGB	0
+/* Outputs 00000000rrrrrggggggbbbbb */
+# define DPI_FORMAT_16BIT_565_RGB_1	1
+/* Outputs 000rrrrr00gggggg000bbbbb */
+# define DPI_FORMAT_16BIT_565_RGB_2	2
+/* Outputs 00rrrrr000gggggg00bbbbb0 */
+# define DPI_FORMAT_16BIT_565_RGB_3	3
+/* Outputs 000000rrrrrrggggggbbbbbb */
+# define DPI_FORMAT_18BIT_666_RGB_1	4
+/* Outputs 00rrrrrr00gggggg00bbbbbb */
+# define DPI_FORMAT_18BIT_666_RGB_2	5
+/* Outputs rrrrrrrrggggggggbbbbbbbb */
+# define DPI_FORMAT_24BIT_888_RGB	6
+
+/* Reverses the polarity of the corresponding signal */
+# define DPI_PIXEL_CLK_INVERT		BIT(10)
+# define DPI_HSYNC_INVERT		BIT(9)
+# define DPI_VSYNC_INVERT		BIT(8)
+# define DPI_OUTPUT_ENABLE_INVERT	BIT(7)
+
+/* Outputs the signal the falling clock edge instead of rising. */
+# define DPI_HSYNC_NEGATE		BIT(6)
+# define DPI_VSYNC_NEGATE		BIT(5)
+# define DPI_OUTPUT_ENABLE_NEGATE	BIT(4)
+
+/* Disables the signal */
+# define DPI_HSYNC_DISABLE		BIT(3)
+# define DPI_VSYNC_DISABLE		BIT(2)
+# define DPI_OUTPUT_ENABLE_DISABLE	BIT(1)
+
+/* Power gate to the device, full reset at 0 -> 1 transition */
+# define DPI_ENABLE			BIT(0)
+
+/* All other registers besides DPI_C return the ID */
+#define DPI_ID			0x04
+# define DPI_ID_VALUE		0x00647069
+
+/* General DPI hardware state. */
+struct vc4_dpi {
+	struct platform_device *pdev;
+
+	struct drm_encoder *encoder;
+	struct drm_connector *connector;
+	struct drm_panel *panel;
+
+	void __iomem *regs;
+
+	struct clk *pixel_clock;
+	struct clk *core_clock;
+};
+
+#define DPI_READ(offset) readl(dpi->regs + (offset))
+#define DPI_WRITE(offset, val) writel(val, dpi->regs + (offset))
+
+/* VC4 DPI encoder KMS struct */
+struct vc4_dpi_encoder {
+	struct vc4_encoder base;
+	struct vc4_dpi *dpi;
+};
+
+static inline struct vc4_dpi_encoder *
+to_vc4_dpi_encoder(struct drm_encoder *encoder)
+{
+	return container_of(encoder, struct vc4_dpi_encoder, base.base);
+}
+
+/* VC4 DPI connector KMS struct */
+struct vc4_dpi_connector {
+	struct drm_connector base;
+	struct vc4_dpi *dpi;
+
+	/* Since the connector is attached to just the one encoder,
+	 * this is the reference to it so we can do the best_encoder()
+	 * hook.
+	 */
+	struct drm_encoder *encoder;
+};
+
+static inline struct vc4_dpi_connector *
+to_vc4_dpi_connector(struct drm_connector *connector)
+{
+	return container_of(connector, struct vc4_dpi_connector, base);
+}
+
+#define DPI_REG(reg) { reg, #reg }
+static const struct {
+	u32 reg;
+	const char *name;
+} dpi_regs[] = {
+	DPI_REG(DPI_C),
+	DPI_REG(DPI_ID),
+};
+
+static void vc4_dpi_dump_regs(struct vc4_dpi *dpi)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(dpi_regs); i++) {
+		DRM_INFO("0x%04x (%s): 0x%08x\n",
+			 dpi_regs[i].reg, dpi_regs[i].name,
+			 DPI_READ(dpi_regs[i].reg));
+	}
+}
+
+#ifdef CONFIG_DEBUG_FS
+int vc4_dpi_debugfs_regs(struct seq_file *m, void *unused)
+{
+	struct drm_info_node *node = (struct drm_info_node *)m->private;
+	struct drm_device *dev = node->minor->dev;
+	struct vc4_dev *vc4 = to_vc4_dev(dev);
+	struct vc4_dpi *dpi = vc4->dpi;
+	int i;
+
+	if (!dpi)
+		return 0;
+
+	for (i = 0; i < ARRAY_SIZE(dpi_regs); i++) {
+		seq_printf(m, "%s (0x%04x): 0x%08x\n",
+			   dpi_regs[i].name, dpi_regs[i].reg,
+			   DPI_READ(dpi_regs[i].reg));
+	}
+
+	return 0;
+}
+#endif
+
+static enum drm_connector_status
+vc4_dpi_connector_detect(struct drm_connector *connector, bool force)
+{
+	struct vc4_dpi_connector *vc4_connector =
+		to_vc4_dpi_connector(connector);
+	struct vc4_dpi *dpi = vc4_connector->dpi;
+
+	if (dpi->panel)
+		return connector_status_connected;
+	else
+		return connector_status_disconnected;
+}
+
+static void vc4_dpi_connector_destroy(struct drm_connector *connector)
+{
+	drm_connector_unregister(connector);
+	drm_connector_cleanup(connector);
+}
+
+static int vc4_dpi_connector_get_modes(struct drm_connector *connector)
+{
+	struct vc4_dpi_connector *vc4_connector =
+		to_vc4_dpi_connector(connector);
+	struct vc4_dpi *dpi = vc4_connector->dpi;
+
+	if (dpi->panel)
+		return drm_panel_get_modes(dpi->panel);
+
+	return 0;
+}
+
+static struct drm_encoder *
+vc4_dpi_connector_best_encoder(struct drm_connector *connector)
+{
+	struct vc4_dpi_connector *dpi_connector =
+		to_vc4_dpi_connector(connector);
+	return dpi_connector->encoder;
+}
+
+static const struct drm_connector_funcs vc4_dpi_connector_funcs = {
+	.dpms = drm_atomic_helper_connector_dpms,
+	.detect = vc4_dpi_connector_detect,
+	.fill_modes = drm_helper_probe_single_connector_modes,
+	.destroy = vc4_dpi_connector_destroy,
+	.reset = drm_atomic_helper_connector_reset,
+	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
+	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
+};
+
+static const struct drm_connector_helper_funcs vc4_dpi_connector_helper_funcs = {
+	.get_modes = vc4_dpi_connector_get_modes,
+	.best_encoder = vc4_dpi_connector_best_encoder,
+};
+
+static struct drm_connector *vc4_dpi_connector_init(struct drm_device *dev,
+						    struct vc4_dpi *dpi)
+{
+	struct drm_connector *connector = NULL;
+	struct vc4_dpi_connector *dpi_connector;
+	int ret = 0;
+
+	dpi_connector = devm_kzalloc(dev->dev, sizeof(*dpi_connector),
+				     GFP_KERNEL);
+	if (!dpi_connector) {
+		ret = -ENOMEM;
+		goto fail;
+	}
+	connector = &dpi_connector->base;
+
+	dpi_connector->encoder = dpi->encoder;
+	dpi_connector->dpi = dpi;
+
+	drm_connector_init(dev, connector, &vc4_dpi_connector_funcs,
+			   DRM_MODE_CONNECTOR_DPI);
+	drm_connector_helper_add(connector, &vc4_dpi_connector_helper_funcs);
+
+	connector->polled = 0;
+	connector->interlace_allowed = 0;
+	connector->doublescan_allowed = 0;
+
+	drm_mode_connector_attach_encoder(connector, dpi->encoder);
+
+	return connector;
+
+ fail:
+	if (connector)
+		vc4_dpi_connector_destroy(connector);
+
+	return ERR_PTR(ret);
+}
+
+static const struct drm_encoder_funcs vc4_dpi_encoder_funcs = {
+	.destroy = drm_encoder_cleanup,
+};
+
+static void vc4_dpi_encoder_disable(struct drm_encoder *encoder)
+{
+	struct vc4_dpi_encoder *vc4_encoder = to_vc4_dpi_encoder(encoder);
+	struct vc4_dpi *dpi = vc4_encoder->dpi;
+
+	drm_panel_disable(dpi->panel);
+
+	clk_disable_unprepare(dpi->pixel_clock);
+
+	drm_panel_unprepare(dpi->panel);
+}
+
+static void vc4_dpi_encoder_enable(struct drm_encoder *encoder)
+{
+	struct drm_display_mode *mode = &encoder->crtc->mode;
+	struct vc4_dpi_encoder *vc4_encoder = to_vc4_dpi_encoder(encoder);
+	struct vc4_dpi *dpi = vc4_encoder->dpi;
+	u32 dpi_c = DPI_ENABLE | DPI_OUTPUT_ENABLE_MODE;
+	int ret;
+
+	ret = drm_panel_prepare(dpi->panel);
+	if (ret) {
+		DRM_ERROR("Panel failed to prepare\n");
+		return;
+	}
+
+	if (dpi->connector->display_info.num_bus_formats) {
+		u32 bus_format = dpi->connector->display_info.bus_formats[0];
+
+		switch (bus_format) {
+		case MEDIA_BUS_FMT_RGB888_1X24:
+			dpi_c |= VC4_SET_FIELD(DPI_FORMAT_24BIT_888_RGB,
+					       DPI_FORMAT);
+			break;
+		case MEDIA_BUS_FMT_BGR888_1X24:
+			dpi_c |= VC4_SET_FIELD(DPI_FORMAT_24BIT_888_RGB,
+					       DPI_FORMAT);
+			dpi_c |= VC4_SET_FIELD(DPI_ORDER_BGR, DPI_ORDER);
+			break;
+		case MEDIA_BUS_FMT_RGB666_1X24_CPADHI:
+			dpi_c |= VC4_SET_FIELD(DPI_FORMAT_18BIT_666_RGB_2,
+					       DPI_FORMAT);
+			break;
+		case MEDIA_BUS_FMT_RGB666_1X18:
+			dpi_c |= VC4_SET_FIELD(DPI_FORMAT_18BIT_666_RGB_1,
+					       DPI_FORMAT);
+			break;
+		case MEDIA_BUS_FMT_RGB565_1X16:
+			dpi_c |= VC4_SET_FIELD(DPI_FORMAT_16BIT_565_RGB_3,
+					       DPI_FORMAT);
+			break;
+		default:
+			DRM_ERROR("Unknown media bus format %d\n", bus_format);
+			break;
+		}
+	}
+
+	if (mode->flags & DRM_MODE_FLAG_NHSYNC)
+		dpi_c |= DPI_HSYNC_INVERT;
+	else if (!(mode->flags & DRM_MODE_FLAG_PHSYNC))
+		dpi_c |= DPI_HSYNC_DISABLE;
+
+	if (mode->flags & DRM_MODE_FLAG_NVSYNC)
+		dpi_c |= DPI_VSYNC_INVERT;
+	else if (!(mode->flags & DRM_MODE_FLAG_PVSYNC))
+		dpi_c |= DPI_VSYNC_DISABLE;
+
+	DPI_WRITE(DPI_C, dpi_c);
+
+	ret = clk_set_rate(dpi->pixel_clock, mode->clock * 1000);
+	if (ret)
+		DRM_ERROR("Failed to set clock rate: %d\n", ret);
+
+	ret = clk_prepare_enable(dpi->pixel_clock);
+	if (ret)
+		DRM_ERROR("Failed to set clock rate: %d\n", ret);
+
+	ret = drm_panel_enable(dpi->panel);
+	if (ret) {
+		DRM_ERROR("Panel failed to enable\n");
+		drm_panel_unprepare(dpi->panel);
+		return;
+	}
+}
+
+static const struct drm_encoder_helper_funcs vc4_dpi_encoder_helper_funcs = {
+	.disable = vc4_dpi_encoder_disable,
+	.enable = vc4_dpi_encoder_enable,
+};
+
+static const struct of_device_id vc4_dpi_dt_match[] = {
+	{ .compatible = "brcm,bcm2835-dpi", .data = NULL },
+	{}
+};
+
+/* Walks the OF graph to find the panel node and then asks DRM to look
+ * up the panel.
+ */
+static struct drm_panel *vc4_dpi_get_panel(struct device *dev)
+{
+	struct device_node *endpoint, *panel_node;
+	struct device_node *np = dev->of_node;
+	struct drm_panel *panel;
+
+	endpoint = of_graph_get_next_endpoint(np, NULL);
+	if (!endpoint) {
+		dev_err(dev, "no endpoint to fetch DPI panel\n");
+		return NULL;
+	}
+
+	/* don't proceed if we have an endpoint but no panel_node tied to it */
+	panel_node = of_graph_get_remote_port_parent(endpoint);
+	of_node_put(endpoint);
+	if (!panel_node) {
+		dev_err(dev, "no valid panel node\n");
+		return NULL;
+	}
+
+	panel = of_drm_find_panel(panel_node);
+	of_node_put(panel_node);
+
+	return panel;
+}
+
+static int vc4_dpi_bind(struct device *dev, struct device *master, void *data)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct drm_device *drm = dev_get_drvdata(master);
+	struct vc4_dev *vc4 = to_vc4_dev(drm);
+	struct vc4_dpi *dpi;
+	struct vc4_dpi_encoder *vc4_dpi_encoder;
+	int ret;
+
+	dpi = devm_kzalloc(dev, sizeof(*dpi), GFP_KERNEL);
+	if (!dpi)
+		return -ENOMEM;
+
+	vc4_dpi_encoder = devm_kzalloc(dev, sizeof(*vc4_dpi_encoder),
+				       GFP_KERNEL);
+	if (!vc4_dpi_encoder)
+		return -ENOMEM;
+	vc4_dpi_encoder->base.type = VC4_ENCODER_TYPE_DPI;
+	vc4_dpi_encoder->dpi = dpi;
+	dpi->encoder = &vc4_dpi_encoder->base.base;
+
+	dpi->pdev = pdev;
+	dpi->regs = vc4_ioremap_regs(pdev, 0);
+	if (IS_ERR(dpi->regs))
+		return PTR_ERR(dpi->regs);
+
+	vc4_dpi_dump_regs(dpi);
+
+	if (DPI_READ(DPI_ID) != DPI_ID_VALUE) {
+		dev_err(dev, "Port returned 0x%08x for ID instead of 0x%08x\n",
+			DPI_READ(DPI_ID), DPI_ID_VALUE);
+		return -ENODEV;
+	}
+
+	dpi->core_clock = devm_clk_get(dev, "core");
+	if (IS_ERR(dpi->core_clock)) {
+		ret = PTR_ERR(dpi->core_clock);
+		if (ret != -EPROBE_DEFER)
+			DRM_ERROR("Failed to get core clock: %d\n", ret);
+		return ret;
+	}
+	dpi->pixel_clock = devm_clk_get(dev, "pixel");
+	if (IS_ERR(dpi->pixel_clock)) {
+		ret = PTR_ERR(dpi->pixel_clock);
+		if (ret != -EPROBE_DEFER)
+			DRM_ERROR("Failed to get pixel clock: %d\n", ret);
+		return ret;
+	}
+
+	ret = clk_prepare_enable(dpi->core_clock);
+	if (ret)
+		DRM_ERROR("Failed to turn on core clock: %d\n", ret);
+
+	dpi->panel = vc4_dpi_get_panel(dev);
+
+	drm_encoder_init(drm, dpi->encoder, &vc4_dpi_encoder_funcs,
+			 DRM_MODE_ENCODER_DPI, NULL);
+	drm_encoder_helper_add(dpi->encoder, &vc4_dpi_encoder_helper_funcs);
+
+	dpi->connector = vc4_dpi_connector_init(drm, dpi);
+	if (IS_ERR(dpi->connector)) {
+		ret = PTR_ERR(dpi->connector);
+		goto err_destroy_encoder;
+	}
+
+	if (dpi->panel)
+		drm_panel_attach(dpi->panel, dpi->connector);
+
+	dev_set_drvdata(dev, dpi);
+
+	vc4->dpi = dpi;
+
+	return 0;
+
+err_destroy_encoder:
+	drm_encoder_cleanup(dpi->encoder);
+	clk_disable_unprepare(dpi->core_clock);
+	return ret;
+}
+
+static void vc4_dpi_unbind(struct device *dev, struct device *master,
+			   void *data)
+{
+	struct drm_device *drm = dev_get_drvdata(master);
+	struct vc4_dev *vc4 = to_vc4_dev(drm);
+	struct vc4_dpi *dpi = dev_get_drvdata(dev);
+
+	if (dpi->panel)
+		drm_panel_detach(dpi->panel);
+
+	vc4_dpi_connector_destroy(dpi->connector);
+	drm_encoder_cleanup(dpi->encoder);
+
+	clk_disable_unprepare(dpi->core_clock);
+
+	vc4->dpi = NULL;
+}
+
+static const struct component_ops vc4_dpi_ops = {
+	.bind   = vc4_dpi_bind,
+	.unbind = vc4_dpi_unbind,
+};
+
+static int vc4_dpi_dev_probe(struct platform_device *pdev)
+{
+	return component_add(&pdev->dev, &vc4_dpi_ops);
+}
+
+static int vc4_dpi_dev_remove(struct platform_device *pdev)
+{
+	component_del(&pdev->dev, &vc4_dpi_ops);
+	return 0;
+}
+
+struct platform_driver vc4_dpi_driver = {
+	.probe = vc4_dpi_dev_probe,
+	.remove = vc4_dpi_dev_remove,
+	.driver = {
+		.name = "vc4_dpi",
+		.of_match_table = vc4_dpi_dt_match,
+	},
+};

drivers/gpu/drm/vc4/vc4_drv.c

@@ -237,6 +237,7 @@ static const struct component_master_ops vc4_drm_ops = {
 
 static struct platform_driver *const component_drivers[] = {
 	&vc4_hdmi_driver,
+	&vc4_dpi_driver,
 	&vc4_crtc_driver,
 	&vc4_hvs_driver,
 	&vc4_v3d_driver,

drivers/gpu/drm/vc4/vc4_drv.h

@@ -16,6 +16,7 @@ struct vc4_dev {
 	struct vc4_hvs *hvs;
 	struct vc4_crtc *crtc[3];
 	struct vc4_v3d *v3d;
+	struct vc4_dpi *dpi;
 
 	struct drm_fbdev_cma *fbdev;
 
@@ -422,6 +423,10 @@ void vc4_debugfs_cleanup(struct drm_minor *minor);
 /* vc4_drv.c */
 void __iomem *vc4_ioremap_regs(struct platform_device *dev, int index);
 
+/* vc4_dpi.c */
+extern struct platform_driver vc4_dpi_driver;
+int vc4_dpi_debugfs_regs(struct seq_file *m, void *unused);
+
 /* vc4_gem.c */
 void vc4_gem_init(struct drm_device *dev);
 void vc4_gem_destroy(struct drm_device *dev);