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From:   Maxime Ripard <maxime.ripard@free-electrons.com>
To:     Chen-Yu Tsai <wens@csie.org>,
        Maxime Ripard <maxime.ripard@free-electrons.com>
Cc:     dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, narmstrong@baylibre.com,
        thomas@vitsch.nl
Subject: [PATCH v4 08/13] drm/sun4i: Add a driver for the display frontend
Date:   Mon, 22 Jan 2018 10:25:22 +0100
Message-Id: <029cdc3478bf89d422f5e8d9e600baf5e48ce4db.1516613040.git-series.maxime.ripard@free-electrons.com>
In-Reply-To: <cover.671c2fcad4ca649d65bd2b9982a8361befa8bfd1.1516613040.git-series.maxime.ripard@free-electrons.com>
References: <cover.671c2fcad4ca649d65bd2b9982a8361befa8bfd1.1516613040.git-series.maxime.ripard@free-electrons.com>
In-Reply-To: <cover.671c2fcad4ca649d65bd2b9982a8361befa8bfd1.1516613040.git-series.maxime.ripard@free-electrons.com>
References: <cover.671c2fcad4ca649d65bd2b9982a8361befa8bfd1.1516613040.git-series.maxime.ripard@free-electrons.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

The display frontend is an hardware block that can be used to implement
some more advanced features like hardware scaling or colorspace
conversions. It can also be used to implement the output format of the VPU.

Let's create a minimal driver for it that will only enable the hardware
scaling features.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
---
 drivers/gpu/drm/sun4i/Makefile         |   3 +-
 drivers/gpu/drm/sun4i/sun4i_drv.c      |  27 +-
 drivers/gpu/drm/sun4i/sun4i_drv.h      |   1 +-
 drivers/gpu/drm/sun4i/sun4i_frontend.c | 389 ++++++++++++++++++++++++++-
 drivers/gpu/drm/sun4i/sun4i_frontend.h |  99 +++++++-
 5 files changed, 514 insertions(+), 5 deletions(-)
 create mode 100644 drivers/gpu/drm/sun4i/sun4i_frontend.c
 create mode 100644 drivers/gpu/drm/sun4i/sun4i_frontend.h

diff --git a/drivers/gpu/drm/sun4i/Makefile b/drivers/gpu/drm/sun4i/Makefile
index 0c2f8c7facae..b660d82011f4 100644
--- a/drivers/gpu/drm/sun4i/Makefile
+++ b/drivers/gpu/drm/sun4i/Makefile
@@ -1,5 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 sun4i-backend-y			+= sun4i_backend.o sun4i_layer.o
+sun4i-frontend-y		+= sun4i_frontend.o
 
 sun4i-drm-y			+= sun4i_drv.o
 sun4i-drm-y			+= sun4i_framebuffer.o
@@ -21,6 +22,6 @@ obj-$(CONFIG_DRM_SUN4I)		+= sun4i-tcon.o
 obj-$(CONFIG_DRM_SUN4I)		+= sun4i_tv.o
 obj-$(CONFIG_DRM_SUN4I)		+= sun6i_drc.o
 
-obj-$(CONFIG_DRM_SUN4I_BACKEND)	+= sun4i-backend.o
+obj-$(CONFIG_DRM_SUN4I_BACKEND)	+= sun4i-backend.o sun4i-frontend.o
 obj-$(CONFIG_DRM_SUN4I_HDMI)	+= sun4i-drm-hdmi.o
 obj-$(CONFIG_DRM_SUN8I_MIXER)	+= sun8i-mixer.o
diff --git a/drivers/gpu/drm/sun4i/sun4i_drv.c b/drivers/gpu/drm/sun4i/sun4i_drv.c
index 75c76cdd82bc..42e68cf3a2e8 100644
--- a/drivers/gpu/drm/sun4i/sun4i_drv.c
+++ b/drivers/gpu/drm/sun4i/sun4i_drv.c
@@ -23,6 +23,7 @@
 #include <drm/drm_of.h>
 
 #include "sun4i_drv.h"
+#include "sun4i_frontend.h"
 #include "sun4i_framebuffer.h"
 #include "sun4i_tcon.h"
 
@@ -98,6 +99,7 @@ static int sun4i_drv_bind(struct device *dev)
 		goto free_drm;
 	}
 	drm->dev_private = drv;
+	INIT_LIST_HEAD(&drv->frontend_list);
 	INIT_LIST_HEAD(&drv->engine_list);
 	INIT_LIST_HEAD(&drv->tcon_list);
 
@@ -185,6 +187,14 @@ static bool sun4i_drv_node_is_frontend(struct device_node *node)
 		of_device_is_compatible(node, "allwinner,sun8i-a33-display-frontend");
 }
 
+static bool sun4i_drv_node_is_supported_frontend(struct device_node *node)
+{
+	if (IS_ENABLED(CONFIG_DRM_SUN4I_BACKEND))
+		return !!of_match_node(sun4i_frontend_of_table, node);
+
+	return false;
+}
+
 static bool sun4i_drv_node_is_tcon(struct device_node *node)
 {
 	return of_device_is_compatible(node, "allwinner,sun4i-a10-tcon") ||
@@ -239,9 +249,11 @@ static int sun4i_drv_add_endpoints(struct device *dev,
 	int count = 0;
 
 	/*
-	 * We don't support the frontend for now, so we will never
-	 * have a device bound. Just skip over it, but we still want
-	 * the rest our pipeline to be added.
+	 * The frontend has been disabled in some of our old device
+	 * trees. If we find a node that is the frontend and is
+	 * disabled, we should just follow through and parse its
+	 * child, but without adding it to the component list.
+	 * Otherwise, we obviously want to add it to the list.
 	 */
 	if (!sun4i_drv_node_is_frontend(node) &&
 	    !of_device_is_available(node))
@@ -254,7 +266,14 @@ static int sun4i_drv_add_endpoints(struct device *dev,
 	if (sun4i_drv_node_is_connector(node))
 		return 0;
 
-	if (!sun4i_drv_node_is_frontend(node)) {
+	/*
+	 * If the device is either just a regular device, or an
+	 * enabled frontend supported by the driver, we add it to our
+	 * component list.
+	 */
+	if (!sun4i_drv_node_is_frontend(node) ||
+	    (sun4i_drv_node_is_supported_frontend(node) &&
+	     of_device_is_available(node))) {
 		/* Add current component */
 		DRM_DEBUG_DRIVER("Adding component %pOF\n", node);
 		drm_of_component_match_add(dev, match, compare_of, node);
diff --git a/drivers/gpu/drm/sun4i/sun4i_drv.h b/drivers/gpu/drm/sun4i/sun4i_drv.h
index a960c89270cc..9c26a345f85c 100644
--- a/drivers/gpu/drm/sun4i/sun4i_drv.h
+++ b/drivers/gpu/drm/sun4i/sun4i_drv.h
@@ -19,6 +19,7 @@
 
 struct sun4i_drv {
 	struct list_head	engine_list;
+	struct list_head	frontend_list;
 	struct list_head	tcon_list;
 
 	struct drm_fbdev_cma	*fbdev;
diff --git a/drivers/gpu/drm/sun4i/sun4i_frontend.c b/drivers/gpu/drm/sun4i/sun4i_frontend.c
new file mode 100644
index 000000000000..ddf6cfa6dd23
--- /dev/null
+++ b/drivers/gpu/drm/sun4i/sun4i_frontend.c
@@ -0,0 +1,389 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2017 Free Electrons
+ * Maxime Ripard <maxime.ripard@free-electrons.com>
+ */
+#include <drm/drmP.h>
+#include <drm/drm_gem_cma_helper.h>
+#include <drm/drm_fb_cma_helper.h>
+
+#include <linux/clk.h>
+#include <linux/component.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/regmap.h>
+#include <linux/reset.h>
+
+#include "sun4i_drv.h"
+#include "sun4i_frontend.h"
+
+static const u32 sun4i_frontend_vert_coef[32] = {
+	0x00004000, 0x000140ff, 0x00033ffe, 0x00043ffd,
+	0x00063efc, 0xff083dfc, 0x000a3bfb, 0xff0d39fb,
+	0xff0f37fb, 0xff1136fa, 0xfe1433fb, 0xfe1631fb,
+	0xfd192ffb, 0xfd1c2cfb, 0xfd1f29fb, 0xfc2127fc,
+	0xfc2424fc, 0xfc2721fc, 0xfb291ffd, 0xfb2c1cfd,
+	0xfb2f19fd, 0xfb3116fe, 0xfb3314fe, 0xfa3611ff,
+	0xfb370fff, 0xfb390dff, 0xfb3b0a00, 0xfc3d08ff,
+	0xfc3e0600, 0xfd3f0400, 0xfe3f0300, 0xff400100,
+};
+
+static const u32 sun4i_frontend_horz_coef[64] = {
+	0x40000000, 0x00000000, 0x40fe0000, 0x0000ff03,
+	0x3ffd0000, 0x0000ff05, 0x3ffc0000, 0x0000ff06,
+	0x3efb0000, 0x0000ff08, 0x3dfb0000, 0x0000ff09,
+	0x3bfa0000, 0x0000fe0d, 0x39fa0000, 0x0000fe0f,
+	0x38fa0000, 0x0000fe10, 0x36fa0000, 0x0000fe12,
+	0x33fa0000, 0x0000fd16, 0x31fa0000, 0x0000fd18,
+	0x2ffa0000, 0x0000fd1a, 0x2cfa0000, 0x0000fc1e,
+	0x29fa0000, 0x0000fc21, 0x27fb0000, 0x0000fb23,
+	0x24fb0000, 0x0000fb26, 0x21fb0000, 0x0000fb29,
+	0x1ffc0000, 0x0000fa2b, 0x1cfc0000, 0x0000fa2e,
+	0x19fd0000, 0x0000fa30, 0x16fd0000, 0x0000fa33,
+	0x14fd0000, 0x0000fa35, 0x11fe0000, 0x0000fa37,
+	0x0ffe0000, 0x0000fa39, 0x0dfe0000, 0x0000fa3b,
+	0x0afe0000, 0x0000fa3e, 0x08ff0000, 0x0000fb3e,
+	0x06ff0000, 0x0000fb40, 0x05ff0000, 0x0000fc40,
+	0x03ff0000, 0x0000fd41, 0x01ff0000, 0x0000fe42,
+};
+
+static void sun4i_frontend_scaler_init(struct sun4i_frontend *frontend)
+{
+	int i;
+
+	for (i = 0; i < 32; i++) {
+		regmap_write(frontend->regs, SUN4I_FRONTEND_CH0_HORZCOEF0_REG(i),
+			     sun4i_frontend_horz_coef[2 * i]);
+		regmap_write(frontend->regs, SUN4I_FRONTEND_CH1_HORZCOEF0_REG(i),
+			     sun4i_frontend_horz_coef[2 * i]);
+		regmap_write(frontend->regs, SUN4I_FRONTEND_CH0_HORZCOEF1_REG(i),
+			     sun4i_frontend_horz_coef[2 * i + 1]);
+		regmap_write(frontend->regs, SUN4I_FRONTEND_CH1_HORZCOEF1_REG(i),
+			     sun4i_frontend_horz_coef[2 * i + 1]);
+		regmap_write(frontend->regs, SUN4I_FRONTEND_CH0_VERTCOEF_REG(i),
+			     sun4i_frontend_vert_coef[i]);
+		regmap_write(frontend->regs, SUN4I_FRONTEND_CH1_VERTCOEF_REG(i),
+			     sun4i_frontend_vert_coef[i]);
+	}
+
+	regmap_update_bits(frontend->regs, SUN4I_FRONTEND_FRM_CTRL_REG,
+			   SUN4I_FRONTEND_FRM_CTRL_COEF_ACCESS_CTRL,
+			   SUN4I_FRONTEND_FRM_CTRL_COEF_ACCESS_CTRL);
+}
+
+int sun4i_frontend_init(struct sun4i_frontend *frontend)
+{
+	return pm_runtime_get_sync(frontend->dev);
+}
+EXPORT_SYMBOL(sun4i_frontend_init);
+
+void sun4i_frontend_exit(struct sun4i_frontend *frontend)
+{
+	pm_runtime_put(frontend->dev);
+}
+EXPORT_SYMBOL(sun4i_frontend_exit);
+
+void sun4i_frontend_update_buffer(struct sun4i_frontend *frontend,
+				  struct drm_plane *plane)
+{
+	struct drm_plane_state *state = plane->state;
+	struct drm_framebuffer *fb = state->fb;
+	dma_addr_t paddr;
+
+	/* Set the line width */
+	DRM_DEBUG_DRIVER("Frontend stride: %d bytes\n", fb->pitches[0]);
+	regmap_write(frontend->regs, SUN4I_FRONTEND_LINESTRD0_REG,
+		     fb->pitches[0]);
+
+	/* Set the physical address of the buffer in memory */
+	paddr = drm_fb_cma_get_gem_addr(fb, state, 0);
+	paddr -= PHYS_OFFSET;
+	DRM_DEBUG_DRIVER("Setting buffer address to %pad\n", &paddr);
+	regmap_write(frontend->regs, SUN4I_FRONTEND_BUF_ADDR0_REG, paddr);
+}
+EXPORT_SYMBOL(sun4i_frontend_update_buffer);
+
+static int sun4i_frontend_drm_format_to_input_fmt(uint32_t fmt, u32 *val)
+{
+	switch (fmt) {
+	case DRM_FORMAT_ARGB8888:
+		*val = 5;
+		return 0;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static int sun4i_frontend_drm_format_to_output_fmt(uint32_t fmt, u32 *val)
+{
+	switch (fmt) {
+	case DRM_FORMAT_XRGB8888:
+	case DRM_FORMAT_ARGB8888:
+		*val = 2;
+		return 0;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+int sun4i_frontend_update_formats(struct sun4i_frontend *frontend,
+				  struct drm_plane *plane, uint32_t out_fmt)
+{
+	struct drm_plane_state *state = plane->state;
+	struct drm_framebuffer *fb = state->fb;
+	u32 out_fmt_val;
+	u32 in_fmt_val;
+	int ret;
+
+	ret = sun4i_frontend_drm_format_to_input_fmt(fb->format->format,
+						     &in_fmt_val);
+	if (ret) {
+		DRM_DEBUG_DRIVER("Invalid input format\n");
+		return ret;
+	}
+
+	ret = sun4i_frontend_drm_format_to_output_fmt(out_fmt, &out_fmt_val);
+	if (ret) {
+		DRM_DEBUG_DRIVER("Invalid output format\n");
+		return ret;
+	}
+
+	/*
+	 * I have no idea what this does exactly, but it seems to be
+	 * related to the scaler FIR filter phase parameters.
+	 */
+	regmap_write(frontend->regs, SUN4I_FRONTEND_CH0_HORZPHASE_REG, 0x400);
+	regmap_write(frontend->regs, SUN4I_FRONTEND_CH1_HORZPHASE_REG, 0x400);
+	regmap_write(frontend->regs, SUN4I_FRONTEND_CH0_VERTPHASE0_REG, 0x400);
+	regmap_write(frontend->regs, SUN4I_FRONTEND_CH1_VERTPHASE0_REG, 0x400);
+	regmap_write(frontend->regs, SUN4I_FRONTEND_CH0_VERTPHASE1_REG, 0x400);
+	regmap_write(frontend->regs, SUN4I_FRONTEND_CH1_VERTPHASE1_REG, 0x400);
+
+	regmap_write(frontend->regs, SUN4I_FRONTEND_INPUT_FMT_REG,
+		     SUN4I_FRONTEND_INPUT_FMT_DATA_MOD(1) |
+		     SUN4I_FRONTEND_INPUT_FMT_DATA_FMT(in_fmt_val) |
+		     SUN4I_FRONTEND_INPUT_FMT_PS(1));
+
+	/*
+	 * TODO: It look like the A31 and A80 at least will need the
+	 * bit 7 (ALPHA_EN) enabled when using a format with alpha (so
+	 * ARGB8888).
+	 */
+	regmap_write(frontend->regs, SUN4I_FRONTEND_OUTPUT_FMT_REG,
+		     SUN4I_FRONTEND_OUTPUT_FMT_DATA_FMT(out_fmt_val));
+
+	return 0;
+}
+EXPORT_SYMBOL(sun4i_frontend_update_formats);
+
+void sun4i_frontend_update_coord(struct sun4i_frontend *frontend,
+				 struct drm_plane *plane)
+{
+	struct drm_plane_state *state = plane->state;
+
+	/* Set height and width */
+	DRM_DEBUG_DRIVER("Frontend size W: %u H: %u\n",
+			 state->crtc_w, state->crtc_h);
+	regmap_write(frontend->regs, SUN4I_FRONTEND_CH0_INSIZE_REG,
+		     SUN4I_FRONTEND_INSIZE(state->src_h >> 16,
+					   state->src_w >> 16));
+	regmap_write(frontend->regs, SUN4I_FRONTEND_CH1_INSIZE_REG,
+		     SUN4I_FRONTEND_INSIZE(state->src_h >> 16,
+					   state->src_w >> 16));
+
+	regmap_write(frontend->regs, SUN4I_FRONTEND_CH0_OUTSIZE_REG,
+		     SUN4I_FRONTEND_OUTSIZE(state->crtc_h, state->crtc_w));
+	regmap_write(frontend->regs, SUN4I_FRONTEND_CH1_OUTSIZE_REG,
+		     SUN4I_FRONTEND_OUTSIZE(state->crtc_h, state->crtc_w));
+
+	regmap_write(frontend->regs, SUN4I_FRONTEND_CH0_HORZFACT_REG,
+		     state->src_w / state->crtc_w);
+	regmap_write(frontend->regs, SUN4I_FRONTEND_CH1_HORZFACT_REG,
+		     state->src_w / state->crtc_w);
+
+	regmap_write(frontend->regs, SUN4I_FRONTEND_CH0_VERTFACT_REG,
+		     state->src_h / state->crtc_h);
+	regmap_write(frontend->regs, SUN4I_FRONTEND_CH1_VERTFACT_REG,
+		     state->src_h / state->crtc_h);
+
+	regmap_write_bits(frontend->regs, SUN4I_FRONTEND_FRM_CTRL_REG,
+			  SUN4I_FRONTEND_FRM_CTRL_REG_RDY,
+			  SUN4I_FRONTEND_FRM_CTRL_REG_RDY);
+}
+EXPORT_SYMBOL(sun4i_frontend_update_coord);
+
+int sun4i_frontend_enable(struct sun4i_frontend *frontend)
+{
+	regmap_write_bits(frontend->regs, SUN4I_FRONTEND_FRM_CTRL_REG,
+			  SUN4I_FRONTEND_FRM_CTRL_FRM_START,
+			  SUN4I_FRONTEND_FRM_CTRL_FRM_START);
+
+	return 0;
+}
+EXPORT_SYMBOL(sun4i_frontend_enable);
+
+static struct regmap_config sun4i_frontend_regmap_config = {
+	.reg_bits	= 32,
+	.val_bits	= 32,
+	.reg_stride	= 4,
+	.max_register	= 0x0a14,
+};
+
+static int sun4i_frontend_bind(struct device *dev, struct device *master,
+			 void *data)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct sun4i_frontend *frontend;
+	struct drm_device *drm = data;
+	struct sun4i_drv *drv = drm->dev_private;
+	struct resource *res;
+	void __iomem *regs;
+
+	frontend = devm_kzalloc(dev, sizeof(*frontend), GFP_KERNEL);
+	if (!frontend)
+		return -ENOMEM;
+
+	dev_set_drvdata(dev, frontend);
+	frontend->dev = dev;
+	frontend->node = dev->of_node;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	regs = devm_ioremap_resource(dev, res);
+	if (IS_ERR(regs))
+		return PTR_ERR(regs);
+
+	frontend->regs = devm_regmap_init_mmio(dev, regs,
+					       &sun4i_frontend_regmap_config);
+	if (IS_ERR(frontend->regs)) {
+		dev_err(dev, "Couldn't create the frontend regmap\n");
+		return PTR_ERR(frontend->regs);
+	}
+
+	frontend->reset = devm_reset_control_get(dev, NULL);
+	if (IS_ERR(frontend->reset)) {
+		dev_err(dev, "Couldn't get our reset line\n");
+		return PTR_ERR(frontend->reset);
+	}
+
+	frontend->bus_clk = devm_clk_get(dev, "ahb");
+	if (IS_ERR(frontend->bus_clk)) {
+		dev_err(dev, "Couldn't get our bus clock\n");
+		return PTR_ERR(frontend->bus_clk);
+	}
+
+	frontend->mod_clk = devm_clk_get(dev, "mod");
+	if (IS_ERR(frontend->mod_clk)) {
+		dev_err(dev, "Couldn't get our mod clock\n");
+		return PTR_ERR(frontend->mod_clk);
+	}
+
+	frontend->ram_clk = devm_clk_get(dev, "ram");
+	if (IS_ERR(frontend->ram_clk)) {
+		dev_err(dev, "Couldn't get our ram clock\n");
+		return PTR_ERR(frontend->ram_clk);
+	}
+
+	list_add_tail(&frontend->list, &drv->frontend_list);
+	pm_runtime_enable(dev);
+
+	return 0;
+}
+
+static void sun4i_frontend_unbind(struct device *dev, struct device *master,
+			    void *data)
+{
+	struct sun4i_frontend *frontend = dev_get_drvdata(dev);
+
+	list_del(&frontend->list);
+	pm_runtime_force_suspend(dev);
+}
+
+static const struct component_ops sun4i_frontend_ops = {
+	.bind	= sun4i_frontend_bind,
+	.unbind	= sun4i_frontend_unbind,
+};
+
+static int sun4i_frontend_probe(struct platform_device *pdev)
+{
+	return component_add(&pdev->dev, &sun4i_frontend_ops);
+}
+
+static int sun4i_frontend_remove(struct platform_device *pdev)
+{
+	component_del(&pdev->dev, &sun4i_frontend_ops);
+
+	return 0;
+}
+
+static int sun4i_frontend_runtime_resume(struct device *dev)
+{
+	struct sun4i_frontend *frontend = dev_get_drvdata(dev);
+	int ret;
+
+	clk_set_rate(frontend->mod_clk, 300000000);
+
+	clk_prepare_enable(frontend->bus_clk);
+	clk_prepare_enable(frontend->mod_clk);
+	clk_prepare_enable(frontend->ram_clk);
+
+	ret = reset_control_reset(frontend->reset);
+	if (ret) {
+		dev_err(dev, "Couldn't reset our device\n");
+		return ret;
+	}
+
+	regmap_update_bits(frontend->regs, SUN4I_FRONTEND_EN_REG,
+			   SUN4I_FRONTEND_EN_EN,
+			   SUN4I_FRONTEND_EN_EN);
+
+	regmap_update_bits(frontend->regs, SUN4I_FRONTEND_BYPASS_REG,
+			   SUN4I_FRONTEND_BYPASS_CSC_EN,
+			   SUN4I_FRONTEND_BYPASS_CSC_EN);
+
+	sun4i_frontend_scaler_init(frontend);
+
+	return 0;
+}
+
+static int sun4i_frontend_runtime_suspend(struct device *dev)
+{
+	struct sun4i_frontend *frontend = dev_get_drvdata(dev);
+
+	clk_disable_unprepare(frontend->ram_clk);
+	clk_disable_unprepare(frontend->mod_clk);
+	clk_disable_unprepare(frontend->bus_clk);
+
+	reset_control_assert(frontend->reset);
+
+	return 0;
+}
+
+static const struct dev_pm_ops sun4i_frontend_pm_ops = {
+	.runtime_resume		= sun4i_frontend_runtime_resume,
+	.runtime_suspend	= sun4i_frontend_runtime_suspend,
+};
+
+const struct of_device_id sun4i_frontend_of_table[] = {
+	{ .compatible = "allwinner,sun8i-a33-display-frontend" },
+	{ }
+};
+EXPORT_SYMBOL(sun4i_frontend_of_table);
+MODULE_DEVICE_TABLE(of, sun4i_frontend_of_table);
+
+static struct platform_driver sun4i_frontend_driver = {
+	.probe		= sun4i_frontend_probe,
+	.remove		= sun4i_frontend_remove,
+	.driver		= {
+		.name		= "sun4i-frontend",
+		.of_match_table	= sun4i_frontend_of_table,
+		.pm		= &sun4i_frontend_pm_ops,
+	},
+};
+module_platform_driver(sun4i_frontend_driver);
+
+MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
+MODULE_DESCRIPTION("Allwinner A10 Display Engine Frontend Driver");
+MODULE_LICENSE("GPL");
diff --git a/drivers/gpu/drm/sun4i/sun4i_frontend.h b/drivers/gpu/drm/sun4i/sun4i_frontend.h
new file mode 100644
index 000000000000..02661ce81f3e
--- /dev/null
+++ b/drivers/gpu/drm/sun4i/sun4i_frontend.h
@@ -0,0 +1,99 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2017 Free Electrons
+ * Maxime Ripard <maxime.ripard@free-electrons.com>
+ */
+
+#ifndef _SUN4I_FRONTEND_H_
+#define _SUN4I_FRONTEND_H_
+
+#include <linux/list.h>
+
+#define SUN4I_FRONTEND_EN_REG			0x000
+#define SUN4I_FRONTEND_EN_EN				BIT(0)
+
+#define SUN4I_FRONTEND_FRM_CTRL_REG		0x004
+#define SUN4I_FRONTEND_FRM_CTRL_COEF_ACCESS_CTRL	BIT(23)
+#define SUN4I_FRONTEND_FRM_CTRL_FRM_START		BIT(16)
+#define SUN4I_FRONTEND_FRM_CTRL_COEF_RDY		BIT(1)
+#define SUN4I_FRONTEND_FRM_CTRL_REG_RDY			BIT(0)
+
+#define SUN4I_FRONTEND_BYPASS_REG		0x008
+#define SUN4I_FRONTEND_BYPASS_CSC_EN			BIT(1)
+
+#define SUN4I_FRONTEND_BUF_ADDR0_REG		0x020
+
+#define SUN4I_FRONTEND_LINESTRD0_REG		0x040
+
+#define SUN4I_FRONTEND_INPUT_FMT_REG		0x04c
+#define SUN4I_FRONTEND_INPUT_FMT_DATA_MOD(mod)		((mod) << 8)
+#define SUN4I_FRONTEND_INPUT_FMT_DATA_FMT(fmt)		((fmt) << 4)
+#define SUN4I_FRONTEND_INPUT_FMT_PS(ps)			(ps)
+
+#define SUN4I_FRONTEND_OUTPUT_FMT_REG		0x05c
+#define SUN4I_FRONTEND_OUTPUT_FMT_DATA_FMT(fmt)		(fmt)
+
+#define SUN4I_FRONTEND_CH0_INSIZE_REG		0x100
+#define SUN4I_FRONTEND_INSIZE(h, w)			((((h) - 1) << 16) | (((w) - 1)))
+
+#define SUN4I_FRONTEND_CH0_OUTSIZE_REG		0x104
+#define SUN4I_FRONTEND_OUTSIZE(h, w)			((((h) - 1) << 16) | (((w) - 1)))
+
+#define SUN4I_FRONTEND_CH0_HORZFACT_REG		0x108
+#define SUN4I_FRONTEND_HORZFACT(i, f)			(((i) << 16) | (f))
+
+#define SUN4I_FRONTEND_CH0_VERTFACT_REG		0x10c
+#define SUN4I_FRONTEND_VERTFACT(i, f)			(((i) << 16) | (f))
+
+#define SUN4I_FRONTEND_CH0_HORZPHASE_REG	0x110
+#define SUN4I_FRONTEND_CH0_VERTPHASE0_REG	0x114
+#define SUN4I_FRONTEND_CH0_VERTPHASE1_REG	0x118
+
+#define SUN4I_FRONTEND_CH1_INSIZE_REG		0x200
+#define SUN4I_FRONTEND_CH1_OUTSIZE_REG		0x204
+#define SUN4I_FRONTEND_CH1_HORZFACT_REG		0x208
+#define SUN4I_FRONTEND_CH1_VERTFACT_REG		0x20c
+
+#define SUN4I_FRONTEND_CH1_HORZPHASE_REG	0x210
+#define SUN4I_FRONTEND_CH1_VERTPHASE0_REG	0x214
+#define SUN4I_FRONTEND_CH1_VERTPHASE1_REG	0x218
+
+#define SUN4I_FRONTEND_CH0_HORZCOEF0_REG(i)	(0x400 + i * 4)
+#define SUN4I_FRONTEND_CH0_HORZCOEF1_REG(i)	(0x480 + i * 4)
+#define SUN4I_FRONTEND_CH0_VERTCOEF_REG(i)	(0x500 + i * 4)
+#define SUN4I_FRONTEND_CH1_HORZCOEF0_REG(i)	(0x600 + i * 4)
+#define SUN4I_FRONTEND_CH1_HORZCOEF1_REG(i)	(0x680 + i * 4)
+#define SUN4I_FRONTEND_CH1_VERTCOEF_REG(i)	(0x700 + i * 4)
+
+struct clk;
+struct device_node;
+struct drm_plane;
+struct regmap;
+struct reset_control;
+
+struct sun4i_frontend {
+	struct list_head	list;
+	struct device		*dev;
+	struct device_node	*node;
+
+	struct clk		*bus_clk;
+	struct clk		*mod_clk;
+	struct clk		*ram_clk;
+	struct regmap		*regs;
+	struct reset_control	*reset;
+};
+
+extern const struct of_device_id sun4i_frontend_of_table[];
+
+int sun4i_frontend_init(struct sun4i_frontend *frontend);
+void sun4i_frontend_exit(struct sun4i_frontend *frontend);
+int sun4i_frontend_enable(struct sun4i_frontend *frontend);
+
+void sun4i_frontend_update_buffer(struct sun4i_frontend *frontend,
+				  struct drm_plane *plane);
+void sun4i_frontend_update_coord(struct sun4i_frontend *frontend,
+				 struct drm_plane *plane);
+int sun4i_frontend_update_formats(struct sun4i_frontend *frontend,
+				  struct drm_plane *plane, uint32_t out_fmt);
+
+#endif /* _SUN4I_FRONTEND_H_ */
-- 
git-series 0.9.1