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From: Sam Ravnborg <sam@ravnborg.org>
To: Boris Brezillon <boris.brezillon@bootlin.com>,
 Rob Herring <robh+dt@kernel.org>, Mark Rutland <mark.rutland@arm.com>,
 Lee Jones <lee.jones@linaro.org>,
 Nicolas Ferre <nicolas.ferre@microchip.com>,
 Alexandre Belloni <alexandre.belloni@bootlin.com>
Subject: [PATCH v1 7/7] drm: add Atmel LCDC display controller support
Date: Sun, 12 Aug 2018 20:46:29 +0200
Message-Id: <20180812184629.3808-7-sam@ravnborg.org>
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Cc: devicetree@vger.kernel.org, linux-pwm@vger.kernel.org,
 Boris Brezillon <boris.brezillon@free-electrons.com>,
 Nicolas Ferre <nicolas.ferre@atmel.com>, dri-devel@lists.freedesktop.org,
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This is a DRM based driver for the Atmel LCDC IP.
There exist today a framebuffer based driver and
this is a re-implmentation of the same on top of DRM.

The rewrite was based on the original fbdev driver
but the driver has also seen inspiration from
the atmel-hlcdc_dc driver and others.

The driver is not a full replacement:
- STN displays are not supported
	Binding support is missing but most of the
	STN specific functionality is otherwise ported
	from the fbdev driver.
- gamma support is missing
	The driver utilises drm_simple_kms_helper and
	this helper lacks support for settting up gamma
- modesetting is not checked (see TODO in file)
- support for extra modes as applicable (and lcd-wiring-mode)
- support for AVR32 (is it relevant?)

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Boris Brezillon <boris.brezillon@free-electrons.com>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
---
 MAINTAINERS                           |    7 +
 drivers/gpu/drm/atmel/Kconfig         |   12 +
 drivers/gpu/drm/atmel/Makefile        |    2 +
 drivers/gpu/drm/atmel/atmel_lcdc-dc.c | 1094 +++++++++++++++++++++++++++++++++
 4 files changed, 1115 insertions(+)
 create mode 100644 drivers/gpu/drm/atmel/atmel_lcdc-dc.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 09ce76a9a1dc..0a594d02a7c0 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4685,6 +4685,13 @@ F:	drivers/gpu/drm/atmel/atmel-hlcdc*
 F:	Documentation/devicetree/bindings/display/atmel/
 T:	git git://anongit.freedesktop.org/drm/drm-misc
 
+DRM DRIVERS FOR ATMEL LCDC
+M:	Sam Ravnborg <sam@ravnborg.org>
+L:	dri-devel@lists.freedesktop.org
+S:	Maintained
+F:	drivers/gpu/drm/atmel/atmel-lcdc*
+F:	Documentation/devicetree/bindings/display/atmel/
+
 DRM DRIVERS FOR BRIDGE CHIPS
 M:	Archit Taneja <architt@codeaurora.org>
 M:	Andrzej Hajda <a.hajda@samsung.com>
diff --git a/drivers/gpu/drm/atmel/Kconfig b/drivers/gpu/drm/atmel/Kconfig
index 7cd3862f9d18..c4c6150f271a 100644
--- a/drivers/gpu/drm/atmel/Kconfig
+++ b/drivers/gpu/drm/atmel/Kconfig
@@ -14,3 +14,15 @@ config DRM_ATMEL_HLCDC
 	help
 	  Choose this option if you have an ATMEL SoC with an HLCDC display
 	  controller (i.e. at91sam9n12, at91sam9x5 family or sama5d3 family).
+
+config DRM_ATMEL_LCDC
+	tristate "DRM Support for ATMEL LCDC Display Controller"
+	depends on DRM && OF && COMMON_CLK && MFD_ATMEL_LCDC && ARM
+	select DRM_ATMEL
+	select DRM_GEM_CMA_HELPER
+	select DRM_KMS_HELPER
+	select DRM_KMS_CMA_HELPER
+	select DRM_PANEL
+	help
+	  Choose this option if you have an ATMEL SoC with an LCDC display
+	  controller (only at91sam9263 or at91sam9rl).
diff --git a/drivers/gpu/drm/atmel/Makefile b/drivers/gpu/drm/atmel/Makefile
index 49dc89f36b73..9fdfada613d2 100644
--- a/drivers/gpu/drm/atmel/Makefile
+++ b/drivers/gpu/drm/atmel/Makefile
@@ -5,3 +5,5 @@ atmel-hlcdc-dc-y := atmel_hlcdc_crtc.o \
 		atmel_hlcdc_plane.o
 
 obj-$(CONFIG_DRM_ATMEL_HLCDC)	+= atmel-hlcdc-dc.o
+
+obj-$(CONFIG_DRM_ATMEL_LCDC)	+= atmel_lcdc-dc.o
diff --git a/drivers/gpu/drm/atmel/atmel_lcdc-dc.c b/drivers/gpu/drm/atmel/atmel_lcdc-dc.c
new file mode 100644
index 000000000000..275a09e2e100
--- /dev/null
+++ b/drivers/gpu/drm/atmel/atmel_lcdc-dc.c
@@ -0,0 +1,1094 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2018 Sam Ravnborg
+ *
+ * The driver is based on atmel_lcdfb which is:
+ * Copyright (C) 2007 Atmel Corporation
+ *
+ * Atmel LCD Controller Display Controller.
+ * A sub-device of the Atmel LCDC IP.
+ *
+ * The Atmel LCD Controller supports in the following configuration:
+ * - TFT only, with BGR565, 8 bits/pixel
+ * - Resolution up to 2048x2048
+ * - Single plane, crtc, one fixed output
+ *
+ * Features not (yet) ported from atmel_lcdfb:
+ * - Support for extra modes (and configurable intensify bit)
+ * - Check modesetting support - lcdc_dc_display_check()
+ * - set color / palette handling
+ * - support for STN displays (partly implemented)
+ * - AVR32 support (relevant?)
+ */
+
+#include <linux/regulator/consumer.h>
+#include <linux/mfd/atmel-lcdc.h>
+#include <linux/of_platform.h>
+#include <linux/pm_runtime.h>
+#include <linux/irqreturn.h>
+#include <linux/device.h>
+#include <linux/regmap.h>
+
+#include <video/videomode.h>
+
+#include <drm/drm_gem_framebuffer_helper.h>
+#include <drm/drm_simple_kms_helper.h>
+#include <drm/drm_gem_cma_helper.h>
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_fb_cma_helper.h>
+#include <drm/drm_crtc_helper.h>
+#include <drm/drm_fb_helper.h>
+#include <drm/drm_fourcc.h>
+#include <drm/drm_vblank.h>
+#include <drm/drm_modes.h>
+#include <drm/drm_panel.h>
+#include <drm/drm_print.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_of.h>
+
+/* Parameters */
+#define ATMEL_LCDC_DMA_BURST_LEN	8	/* words */
+
+/**
+ * struct atmel_lcdc_dc_desc - CPU specific configuration properties
+ */
+struct atmel_lcdc_dc_desc {
+	int guard_time;
+	int fifo_size;
+	int min_width;
+	int min_height;
+	int max_width;
+	int max_height;
+	bool have_hozval;
+	bool have_alt_pixclock;
+};
+
+/* private data */
+struct lcdc_dc {
+	const struct atmel_lcdc_dc_desc *desc;
+	struct atmel_mfd_lcdc *mfd_lcdc;
+	struct regulator *lcd_supply;
+	struct drm_fbdev_cma *fbdev;
+	struct drm_bridge *bridge;
+	struct drm_panel *panel;
+	struct regmap *regmap;
+	struct device *dev;
+
+	struct drm_simple_display_pipe pipe;
+	struct work_struct reset_lcdc_work;
+	struct drm_connector connector;
+};
+
+/* Configuration of individual CPU's */
+static const struct atmel_lcdc_dc_desc atmel_lcdc_dc_at91sam9261 = {
+	.guard_time = 1,
+	.fifo_size = 512,
+	.min_width = 0,
+	.min_height = 0,
+	.max_width = 2048,
+	.max_height = 2048,
+	.have_hozval = true,
+	.have_alt_pixclock = false,
+};
+
+static const struct atmel_lcdc_dc_desc atmel_lcdc_dc_at91sam9263 = {
+	.guard_time = 1,
+	.fifo_size = 2048,
+	.min_width = 0,
+	.min_height = 0,
+	.max_width = 2048,
+	.max_height = 2048,
+	.have_hozval = false,
+	.have_alt_pixclock = false,
+};
+
+static const struct atmel_lcdc_dc_desc atmel_lcdc_dc_at91sam9g10 = {
+	.guard_time = 1,
+	.fifo_size = 512,
+	.min_width = 0,
+	.min_height = 0,
+	.max_width = 2048,
+	.max_height = 2048,
+	.have_hozval = true,
+	.have_alt_pixclock = false,
+};
+
+static const struct atmel_lcdc_dc_desc atmel_lcdc_dc_at91sam9g45 = {
+	.guard_time = 1,
+	.fifo_size = 512,
+	.min_width = 0,
+	.min_height = 0,
+	.max_width = 2048,
+	.max_height = 2048,
+	.have_hozval = false,
+	.have_alt_pixclock = true,
+};
+
+static const struct atmel_lcdc_dc_desc atmel_lcdc_dc_at91sam9g46 = {
+	.guard_time = 1,
+	.fifo_size = 512,
+	.min_width = 0,
+	.min_height = 0,
+	.max_width = 2048,
+	.max_height = 2048,
+	.have_hozval = false,
+	.have_alt_pixclock = false,
+};
+
+static const struct atmel_lcdc_dc_desc atmel_lcdc_dc_at91sam9m10 = {
+	.guard_time = 1,
+	.fifo_size = 512,
+	.min_width = 0,
+	.min_height = 0,
+	.max_width = 2048,
+	.max_height = 2048,
+	.have_hozval = false,
+	.have_alt_pixclock = false,
+};
+
+static const struct atmel_lcdc_dc_desc atmel_lcdc_dc_at91sam9m11 = {
+	.guard_time = 1,
+	.fifo_size = 512,
+	.min_width = 0,
+	.min_height = 0,
+	.max_width = 2048,
+	.max_height = 2048,
+	.have_hozval = false,
+	.have_alt_pixclock = false,
+};
+
+static const struct atmel_lcdc_dc_desc atmel_lcdc_dc_at91sam9rl = {
+	.guard_time = 1,
+	.fifo_size = 512,
+	.min_width = 0,
+	.min_height = 0,
+	.max_width = 2048,
+	.max_height = 2048,
+	.have_hozval = false,
+	.have_alt_pixclock = false,
+};
+
+static const struct of_device_id atmel_lcdc_of_match[] = {
+	{
+		.compatible = "atmel,at91sam9261-lcdc-mfd",
+		.data = &atmel_lcdc_dc_at91sam9261,
+	}, {
+		.compatible = "atmel,at91sam9263-lcdc-mfd",
+		.data = &atmel_lcdc_dc_at91sam9263,
+	}, {
+		.compatible = "atmel,at91sam9g10-lcdc-mfd",
+		.data = &atmel_lcdc_dc_at91sam9g10,
+	}, {
+		.compatible = "atmel,at91sam9g45-lcdc-mfd",
+		.data = &atmel_lcdc_dc_at91sam9g45,
+	}, {
+		.compatible = "atmel,at91sam9g46-lcdc-mfd",
+		.data = &atmel_lcdc_dc_at91sam9g46,
+	}, {
+		.compatible = "atmel,at91sam9m10-lcdc-mfd",
+		.data = &atmel_lcdc_dc_at91sam9m10,
+	}, {
+		.compatible = "atmel,at91sam9m11-lcdc-mfd",
+		.data = &atmel_lcdc_dc_at91sam9m11,
+	}, {
+		.compatible = "atmel,at91sam9rl-lcdc-mfd",
+		.data = &atmel_lcdc_dc_at91sam9rl,
+	},
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, atmel_lcdc_of_match);
+
+/*
+ * The Atmel LCD controller display-controller supports several formats but
+ * this driver supports only a small subset.
+ * TODO: atmel_lcdfb supports more - port it over
+ * Maybe actual wiring will impact mode support?
+ */
+static const u32 lcdc_dc_formats[] = {
+	DRM_FORMAT_BGR565,
+};
+
+/* Start LCD Controller (DMA + PWR) */
+static void lcdc_dc_start(struct lcdc_dc *lcdc_dc)
+{
+	// Enable DMA
+	regmap_write(lcdc_dc->regmap, ATMEL_LCDC_DMACON, ATMEL_LCDC_DMAEN);
+	// Enable LCD
+	regmap_write(lcdc_dc->regmap, ATMEL_LCDC_PWRCON,
+		     (lcdc_dc->desc->guard_time << ATMEL_LCDC_GUARDT_OFFSET)
+		     | ATMEL_LCDC_PWR);
+}
+
+/* Stop LCD Controller (PWR + DMA) */
+static void lcdc_dc_stop(struct lcdc_dc *lcdc_dc)
+{
+	unsigned int pwrcon;
+
+	might_sleep();
+
+	/* Turn off the LCD controller and the DMA controller */
+	regmap_write(lcdc_dc->regmap, ATMEL_LCDC_PWRCON,
+			lcdc_dc->desc->guard_time << ATMEL_LCDC_GUARDT_OFFSET);
+
+	/* Wait for the LCDC core to become idle */
+	regmap_read_poll_timeout(lcdc_dc->regmap, ATMEL_LCDC_PWRCON, pwrcon,
+				 !(pwrcon & ATMEL_LCDC_BUSY), 100, 10000);
+	regmap_write(lcdc_dc->regmap, ATMEL_LCDC_DMACON, !(ATMEL_LCDC_DMAEN));
+}
+
+static void lcdc_dc_start_clock(struct lcdc_dc *lcdc_dc)
+{
+	clk_prepare_enable(lcdc_dc->mfd_lcdc->bus_clk);
+	clk_prepare_enable(lcdc_dc->mfd_lcdc->lcdc_clk);
+}
+
+static void lcdc_dc_stop_clock(struct lcdc_dc *lcdc_dc)
+{
+	clk_disable_unprepare(lcdc_dc->mfd_lcdc->bus_clk);
+	clk_disable_unprepare(lcdc_dc->mfd_lcdc->lcdc_clk);
+}
+
+static int lcdc_dc_display_check(struct drm_simple_display_pipe *pipe,
+				 struct drm_plane_state *pstate,
+				 struct drm_crtc_state *cstate)
+{
+	const struct drm_display_mode *dmode;
+	struct drm_framebuffer *old_fb;
+	struct drm_framebuffer *fb;
+
+	dmode = &cstate->mode;
+	old_fb = pipe->plane.state->fb;
+	fb = pstate->fb;
+
+	/* Check timing? */
+	/* TODO */
+
+	return 0;
+}
+
+/* Horizontal size of LCD module - configuration dependent */
+static unsigned int compute_hozval(struct lcdc_dc *lcdc_dc, unsigned int width)
+{
+	unsigned int valid_lcdd_data_line;
+	unsigned int hoz_display_size;
+	unsigned int disptype;
+	unsigned int scanmode;
+	unsigned int ifwidth;
+	unsigned int lcdcon2;
+
+	if (!lcdc_dc->desc->have_hozval)
+		return width;
+
+	regmap_read(lcdc_dc->regmap, ATMEL_LCDC_LCDCON2, &lcdcon2);
+	disptype = lcdcon2 & ATMEL_LCDC_DISTYPE;
+
+	if (disptype == ATMEL_LCDC_DISTYPE_TFT)
+		return width;
+
+	ifwidth = lcdcon2 & ATMEL_LCDC_IFWIDTH;
+	scanmode = lcdcon2 & ATMEL_LCDC_SCANMOD;
+
+	/*
+	 * STN display
+	 * Based on algorithm from datasheet calculate hozval
+	 */
+	if (disptype == ATMEL_LCDC_DISTYPE_STNCOLOR)
+		hoz_display_size = width * 3;
+	else
+		hoz_display_size = width;
+
+	switch (ifwidth) {
+	case ATMEL_LCDC_IFWIDTH_4:
+		valid_lcdd_data_line = 4;
+		break;
+	case ATMEL_LCDC_IFWIDTH_8:
+		if (scanmode == ATMEL_LCDC_SCANMOD_DUAL)
+			valid_lcdd_data_line = 4;
+		else
+			valid_lcdd_data_line = 8;
+		break;
+	default:
+		valid_lcdd_data_line = 8;
+		break;
+	}
+
+	return DIV_ROUND_UP(hoz_display_size, valid_lcdd_data_line);
+}
+
+static void set_vertical_timing(struct lcdc_dc *lcdc_dc,
+				struct drm_display_mode *dmode)
+{
+	unsigned int tim1;
+	unsigned int vfp;
+	unsigned int vbp;
+	unsigned int vpw;
+	unsigned int vhdly;
+
+	/* VFP: Vertical Front Porch */
+	vfp = dmode->vsync_start - dmode->vdisplay;
+
+	/* VBP: Vertical Back Porch */
+	vbp = dmode->vtotal - dmode->vsync_end;
+
+	/* VPW: Vertical Synchronization pulse width */
+	vpw = dmode->vsync_end - dmode->vsync_start - 1;
+
+	/* VHDLY: Vertical to horizontal delay */
+	vhdly = 0;
+
+	tim1 = vfp << ATMEL_LCDC_VFP_OFFSET |
+	       vbp << ATMEL_LCDC_VBP_OFFSET |
+	       vpw << ATMEL_LCDC_VPW_OFFSET |
+	       vhdly << ATMEL_LCDC_VHDLY_OFFSET;
+
+	DRM_DEV_DEBUG(lcdc_dc->dev, " TIM1 = %08x\n", tim1);
+	regmap_write(lcdc_dc->regmap, ATMEL_LCDC_TIM1, tim1);
+}
+
+static void set_horizontal_timing(struct lcdc_dc *lcdc_dc,
+				  struct drm_display_mode *dmode)
+{
+	unsigned int tim2;
+	unsigned int hbp;
+	unsigned int hpw;
+	unsigned int hfp;
+
+	/* HBP: Horizontal Back Porch */
+	hbp = dmode->htotal - dmode->hsync_end - 1;
+
+	/* HPW: Horizontal synchronization pulse width */
+	hpw = dmode->hsync_end - dmode->hsync_start - 1;
+
+	/* HFP: Horizontal Front Porch */
+	hfp = dmode->hsync_start - dmode->hdisplay - 2;
+
+	tim2 = hbp << ATMEL_LCDC_HBP_OFFSET |
+	       hpw << ATMEL_LCDC_HPW_OFFSET |
+	       hfp << ATMEL_LCDC_HFP_OFFSET;
+
+	DRM_DEV_DEBUG(lcdc_dc->dev, " TIM2 = %08x\n", tim2);
+	regmap_write(lcdc_dc->regmap, ATMEL_LCDC_TIM2, tim2);
+}
+
+static void lcdc_dc_crtc_mode_set_nofb(struct lcdc_dc *lcdc_dc)
+{
+	struct drm_display_mode *dmode;
+	unsigned int hozval_linesz;
+	unsigned int value;
+
+	dmode = &lcdc_dc->pipe.crtc.state->adjusted_mode;
+
+	/* Vertical & horizontal timing */
+	set_vertical_timing(lcdc_dc, dmode);
+	set_horizontal_timing(lcdc_dc, dmode);
+
+	/* Horizontal value (aka line size) */
+	hozval_linesz = compute_hozval(lcdc_dc, dmode->crtc_hdisplay);
+
+	/* Display size */
+	value = (hozval_linesz - 1) << ATMEL_LCDC_HOZVAL_OFFSET;
+	value |= dmode->crtc_vdisplay - 1;
+	DRM_DEV_DEBUG(lcdc_dc->dev, " LCDFRMCFG = %08x\n", value);
+	regmap_write(lcdc_dc->regmap, ATMEL_LCDC_LCDFRMCFG, value);
+
+	/* FIFO Threshold: Use formula from data sheet */
+	value = lcdc_dc->desc->fifo_size - (2 * ATMEL_LCDC_DMA_BURST_LEN + 3);
+	DRM_DEV_DEBUG(lcdc_dc->dev, " FIFO = %08x\n", value);
+	regmap_write(lcdc_dc->regmap, ATMEL_LCDC_FIFO, value);
+
+	/*
+	 * Toggle LCD_MODE every frame
+	 * Note: register not documented, this is from atmel_lcdfb
+	 */
+	regmap_write(lcdc_dc->regmap, ATMEL_LCDC_MVAL, 0);
+}
+
+static void lcdc_dc_enable(struct lcdc_dc *lcdc_dc,
+			   struct drm_device *drm,
+			   struct drm_crtc *crtc)
+{
+	const struct drm_format_info *format;
+	struct drm_display_mode *dmode;
+	unsigned long clk_value_khz;
+	unsigned int pix_factor;
+	unsigned int lcdcon1;
+	unsigned int lcdcon2;
+	u32 bus_flags;
+
+	dmode = &lcdc_dc->pipe.crtc.state->adjusted_mode;
+	format = crtc->primary->state->fb->format;
+
+	/* Control register 1 */
+
+	/* Set pixel clock */
+	if (lcdc_dc->desc->have_alt_pixclock)
+		pix_factor = 1;
+	else
+		pix_factor = 2;
+
+	clk_value_khz = clk_get_rate(lcdc_dc->mfd_lcdc->lcdc_clk) / 1000;
+	lcdcon1 = DIV_ROUND_UP(clk_value_khz, dmode->clock);
+
+	if (lcdcon1 < pix_factor) {
+		DRM_DEV_INFO(lcdc_dc->dev, "Bypassing pixel clock divider\n");
+		regmap_write(lcdc_dc->regmap,
+			     ATMEL_LCDC_LCDCON1, ATMEL_LCDC_BYPASS);
+	} else {
+
+		lcdcon1 = (lcdcon1 / pix_factor) - 1;
+		DRM_DEV_DEBUG(lcdc_dc->dev, "CLKVAL = 0x%08x\n", lcdcon1);
+		regmap_write(lcdc_dc->regmap, ATMEL_LCDC_LCDCON1,
+			     lcdcon1 << ATMEL_LCDC_CLKVAL_OFFSET);
+		dmode->clock = clk_value_khz / (pix_factor * (lcdcon1 + 1));
+		DRM_DEV_DEBUG(lcdc_dc->dev, "updated pixclk:  %u KHz\n",
+					dmode->clock);
+	}
+
+	/* Control register 2 */
+	/* Only TFT supported (Controller supports STN too) */
+	lcdcon2 = ATMEL_LCDC_DISTYPE_TFT;
+
+	/* scan mode (STN only) */
+	if (dmode->flags & DRM_MODE_FLAG_DBLSCAN)
+		lcdcon2 |= ATMEL_LCDC_SCANMOD_DUAL;
+	else
+		lcdcon2 |= ATMEL_LCDC_SCANMOD_SINGLE;
+
+	/* Interface width 4 bits (STN only) */
+	lcdcon2 |= ATMEL_LCDC_IFWIDTH_4;
+
+	/* bits per pixel */
+	switch (format->depth) {
+	case 1:
+		lcdcon2 |= ATMEL_LCDC_PIXELSIZE_1;
+		break;
+	case 2:
+		lcdcon2 |= ATMEL_LCDC_PIXELSIZE_2;
+		break;
+	case 4:
+		lcdcon2 |= ATMEL_LCDC_PIXELSIZE_4;
+		break;
+	case 8:
+		lcdcon2 |= ATMEL_LCDC_PIXELSIZE_8;
+		break;
+	case 15:
+		/* fall through */
+	case 16:
+		lcdcon2 |= ATMEL_LCDC_PIXELSIZE_16;
+		break;
+	case 24:
+		lcdcon2 |= ATMEL_LCDC_PIXELSIZE_24;
+		break;
+	case 32:
+		lcdcon2 |= ATMEL_LCDC_PIXELSIZE_32;
+		break;
+	default:
+		DRM_DEV_ERROR(lcdc_dc->dev, "Unexpected depth (%d)",
+			      format->depth);
+		break;
+	}
+
+	/* Polarity normal */
+	lcdcon2 |= ATMEL_LCDC_INVVD_NORMAL;
+
+	/* vsync polarity */
+	if (dmode->flags & DRM_MODE_FLAG_PVSYNC)
+		lcdcon2 |= ATMEL_LCDC_INVFRAME_INVERTED;
+	else
+		lcdcon2 |= ATMEL_LCDC_INVFRAME_NORMAL;
+
+	/* hsync polarity */
+	if (dmode->flags & DRM_MODE_FLAG_PHSYNC)
+		lcdcon2 |= ATMEL_LCDC_INVLINE_INVERTED;
+	else
+		lcdcon2 |= ATMEL_LCDC_INVLINE_NORMAL;
+
+	bus_flags = lcdc_dc->connector.display_info.bus_flags;
+
+	/* dot clock (pix clock) polarity */
+	if (bus_flags & DRM_BUS_FLAG_PIXDATA_NEGEDGE)
+		lcdcon2 |= ATMEL_LCDC_INVCLK_INVERTED;
+	else
+		lcdcon2 |= ATMEL_LCDC_INVCLK_NORMAL;
+
+	/* Date Enable polarity */
+	if (bus_flags & DRM_BUS_FLAG_DE_LOW)
+		lcdcon2 |= ATMEL_LCDC_INVDVAL_INVERTED;
+	else
+		lcdcon2 |= ATMEL_LCDC_INVDVAL_NORMAL;
+
+	/* Clock is always active */
+	lcdcon2 |= ATMEL_LCDC_CLKMOD_ALWAYSACTIVE;
+
+	/* Memory layout */
+	if (format->format & DRM_FORMAT_BIG_ENDIAN)
+		lcdcon2 |= ATMEL_LCDC_MEMOR_BIG;
+	else
+		lcdcon2 |= ATMEL_LCDC_MEMOR_LITTLE;
+
+	regmap_write(lcdc_dc->regmap, ATMEL_LCDC_LCDCON2, lcdcon2);
+
+	lcdc_dc_start(lcdc_dc);
+
+	drm_crtc_vblank_on(crtc);
+}
+
+static void lcdc_dc_display_enable(struct drm_simple_display_pipe *pipe,
+				   struct drm_crtc_state *cstate,
+				   struct drm_plane_state *plane_state)
+{
+	struct lcdc_dc *lcdc_dc;
+	struct drm_device *drm;
+	struct drm_crtc *crtc;
+	int ret;
+
+	crtc = &pipe->crtc;
+	drm = crtc->dev;
+	lcdc_dc = drm->dev_private;
+
+	ret = regulator_enable(lcdc_dc->lcd_supply);
+	if (ret)
+		DRM_DEV_ERROR(lcdc_dc->dev, "regulator_enable failed (%d)",
+			      ret);
+
+	drm_panel_prepare(lcdc_dc->panel);
+	lcdc_dc_crtc_mode_set_nofb(lcdc_dc);
+
+	/*
+	 * drm_simple_kms_helper have no support for gamma setup.
+	 * Add: lcdc_dc_setcolor(lcdc_dc, crtc); when we have it
+	 */
+	lcdc_dc_enable(lcdc_dc, drm, crtc);
+
+	drm_panel_enable(lcdc_dc->panel);
+}
+
+static void lcdc_dc_display_disable(struct drm_simple_display_pipe *pipe)
+{
+	struct lcdc_dc *lcdc_dc;
+	struct drm_device *drm;
+	struct drm_crtc *crtc;
+
+	crtc = &pipe->crtc;
+	drm = crtc->dev;
+	lcdc_dc = drm->dev_private;
+
+	drm_crtc_vblank_off(crtc);
+
+	drm_panel_disable(lcdc_dc->panel);
+
+	lcdc_dc_stop(lcdc_dc);
+
+	drm_panel_unprepare(lcdc_dc->panel);
+	regulator_disable(lcdc_dc->lcd_supply);
+}
+
+/* Update DMA config */
+static void lcdc_dc_update_dma(struct lcdc_dc *lcdc_dc,
+			       struct drm_simple_display_pipe *pipe)
+{
+	struct drm_plane_state *plane_state;
+	struct drm_framebuffer *fb;
+	unsigned int burst_length;
+	unsigned int frame_size;
+	dma_addr_t dma_addr;
+
+	plane_state = pipe->plane.state;
+	fb = plane_state->fb;
+
+	if (fb) {
+		unsigned int dmafrmcfg;
+
+		dma_addr = drm_fb_cma_get_gem_addr(fb, pipe->plane.state, 0);
+
+		/* Set frame buffer DMA base address */
+		regmap_write(lcdc_dc->regmap, ATMEL_LCDC_DMABADDR1, dma_addr);
+
+		/*
+		 * Set frame size and burst length
+		 * Frame_size equals size of visible area * bits / 32
+		 * (size in 32 bit words)
+		 */
+		frame_size = plane_state->crtc_w * plane_state->crtc_h;
+		frame_size = (frame_size * fb->format->depth) / 32;
+
+		burst_length = ATMEL_LCDC_DMA_BURST_LEN - 1;
+
+		dmafrmcfg = frame_size;
+		dmafrmcfg |= burst_length << ATMEL_LCDC_BLENGTH_OFFSET;
+
+		regmap_write(lcdc_dc->regmap, ATMEL_LCDC_DMAFRMCFG, dmafrmcfg);
+	}
+}
+
+static void lcdc_dc_update_event(struct drm_simple_display_pipe *pipe)
+{
+	struct drm_pending_vblank_event *event;
+	struct drm_crtc *crtc;
+
+	crtc = &pipe->crtc;
+	if (!crtc)
+		return;
+
+	spin_lock_irq(&crtc->dev->event_lock);
+	event = crtc->state->event;
+	if (event) {
+		crtc->state->event = NULL;
+
+		if (drm_crtc_vblank_get(crtc) == 0)
+			drm_crtc_arm_vblank_event(crtc, event);
+		else
+			drm_crtc_send_vblank_event(crtc, event);
+	}
+	spin_unlock_irq(&crtc->dev->event_lock);
+}
+
+static void lcdc_dc_display_update(struct drm_simple_display_pipe *pipe,
+				   struct drm_plane_state *old_pstate)
+{
+	struct drm_device *drm;
+	struct lcdc_dc *lcdc_dc;
+
+	drm = pipe->crtc.dev;
+	lcdc_dc = drm->dev_private;
+
+	/* Re-initialize the DMA engine... */
+	lcdc_dc_update_dma(lcdc_dc, pipe);
+
+	/* vblank event handling */
+	lcdc_dc_update_event(pipe);
+}
+
+static int lcdc_dc_display_enable_vblank(struct drm_simple_display_pipe *pipe)
+{
+	struct drm_crtc *crtc;
+	struct lcdc_dc *lcdc_dc;
+
+	crtc  = &pipe->crtc;
+	lcdc_dc = crtc->dev->dev_private;
+
+	/* Last line interrupt enable */
+	regmap_write(lcdc_dc->regmap, ATMEL_LCDC_IER, ATMEL_LCDC_LSTLNI);
+
+	return 0;
+}
+
+static void lcdc_dc_display_disable_vblank(struct drm_simple_display_pipe *pipe)
+{
+	struct drm_crtc *crtc;
+	struct lcdc_dc *lcdc_dc;
+
+	crtc  = &pipe->crtc;
+	lcdc_dc = crtc->dev->dev_private;
+
+	/* Last line interrupt disable */
+	regmap_write(lcdc_dc->regmap, ATMEL_LCDC_IDR, ATMEL_LCDC_LSTLNI);
+}
+
+static const struct drm_simple_display_pipe_funcs lcdc_dc_display_funcs = {
+	.check = lcdc_dc_display_check,
+	.enable = lcdc_dc_display_enable,
+	.disable = lcdc_dc_display_disable,
+	.update = lcdc_dc_display_update,
+	.prepare_fb = drm_gem_fb_simple_display_pipe_prepare_fb,
+	.enable_vblank = lcdc_dc_display_enable_vblank,
+	.disable_vblank = lcdc_dc_display_disable_vblank,
+};
+
+static const struct drm_mode_config_funcs mode_config_funcs = {
+	.fb_create = drm_gem_fb_create,
+	.atomic_check = drm_atomic_helper_check,
+	.atomic_commit = drm_atomic_helper_commit,
+};
+
+/* scheduled worker to reset LCD */
+static void reset_lcdc_work(struct work_struct *work)
+{
+	struct lcdc_dc *lcdc_dc;
+
+	lcdc_dc = container_of(work, struct lcdc_dc, reset_lcdc_work);
+
+	lcdc_dc_stop(lcdc_dc);
+	lcdc_dc_start(lcdc_dc);
+}
+
+static irqreturn_t lcdc_dc_irq_handler(int irq, void *arg)
+{
+	struct lcdc_dc *lcdc_dc;
+	struct drm_device *drm;
+	unsigned int status;
+	struct device *dev;
+	unsigned int imr;
+	unsigned int isr;
+
+	drm = arg;
+	lcdc_dc = drm->dev_private;
+	dev = lcdc_dc->dev;
+
+	regmap_read(lcdc_dc->regmap, ATMEL_LCDC_IMR, &imr);
+	regmap_read(lcdc_dc->regmap, ATMEL_LCDC_ISR, &isr);
+	status = imr & isr;
+	if (!status)
+		return IRQ_NONE;
+
+	if (status & ATMEL_LCDC_LSTLNI)
+		drm_crtc_handle_vblank(&lcdc_dc->pipe.crtc);
+
+	if (status & ATMEL_LCDC_UFLWI) {
+		DRM_DEV_INFO(dev, "FIFO underflow %#x\n", status);
+		/* reset DMA and FIFO to avoid screen shifting */
+		schedule_work(&lcdc_dc->reset_lcdc_work);
+	}
+	if (status & ATMEL_LCDC_OWRI)
+		DRM_DEV_INFO(dev, "FIFO overwrite interrupt");
+
+	if (status & ATMEL_LCDC_MERI)
+		DRM_DEV_INFO(dev, "DMA memory error");
+
+	/* Clear all reported (from ISR) interrupts */
+	regmap_write(lcdc_dc->regmap, ATMEL_LCDC_ICR, isr);
+
+	return IRQ_HANDLED;
+}
+
+static int lcdc_dc_irq_postinstall(struct drm_device *dev)
+{
+	struct lcdc_dc *lcdc_dc;
+	unsigned int ier;
+
+	lcdc_dc = dev->dev_private;
+
+	ier = 0;
+	/* FIFO underflow interrupt enable */
+	ier |= ATMEL_LCDC_UFLWI;
+	/* FIFO overwrite interrupt enable */
+	ier |= ATMEL_LCDC_OWRI;
+	/* DMA memory error interrupt enable */
+	ier |= ATMEL_LCDC_MERI;
+	regmap_write(lcdc_dc->regmap, ATMEL_LCDC_IER, ier);
+
+	return 0;
+}
+
+static void lcdc_dc_irq_uninstall(struct drm_device *dev)
+{
+	struct lcdc_dc *lcdc_dc;
+	unsigned int isr;
+
+	lcdc_dc  = dev->dev_private;
+
+	/* disable all interrupts */
+	regmap_write(lcdc_dc->regmap, ATMEL_LCDC_IDR, ~0);
+	regmap_write(lcdc_dc->regmap, ATMEL_LCDC_ICR, ~0);
+
+	/* Clear any pending interrupts */
+	regmap_read(lcdc_dc->regmap, ATMEL_LCDC_ISR, &isr);
+}
+
+DEFINE_DRM_GEM_CMA_FOPS(lcdc_dc_drm_fops);
+
+static struct drm_driver lcdc_dc_drm_driver = {
+	.driver_features = DRIVER_HAVE_IRQ |
+			   DRIVER_GEM |
+			   DRIVER_MODESET |
+			   DRIVER_PRIME |
+			   DRIVER_ATOMIC,
+	.name = "atmel-lcdc",
+	.desc = "Atmel LCD Display Controller DRM",
+	.date = "20180808",
+	.major = 1,
+	.minor = 0,
+	.patchlevel = 0,
+
+	.lastclose = drm_fb_helper_lastclose,
+	.fops = &lcdc_dc_drm_fops,
+
+	.irq_handler = lcdc_dc_irq_handler,
+	.irq_preinstall = lcdc_dc_irq_uninstall,
+	.irq_postinstall = lcdc_dc_irq_postinstall,
+	.irq_uninstall = lcdc_dc_irq_uninstall,
+
+	.dumb_create = drm_gem_cma_dumb_create,
+
+	.gem_print_info = drm_gem_cma_print_info,
+	.gem_vm_ops = &drm_gem_cma_vm_ops,
+
+	.prime_handle_to_fd = drm_gem_prime_handle_to_fd,
+	.prime_fd_to_handle = drm_gem_prime_fd_to_handle,
+
+	.gem_prime_import = drm_gem_prime_import,
+	.gem_prime_export = drm_gem_prime_export,
+
+	.gem_prime_get_sg_table	= drm_gem_cma_prime_get_sg_table,
+	.gem_free_object_unlocked = drm_gem_cma_free_object,
+
+	.gem_prime_import_sg_table = drm_gem_cma_prime_import_sg_table,
+	.gem_prime_vmap = drm_gem_cma_prime_vmap,
+	.gem_prime_vunmap = drm_gem_cma_prime_vunmap,
+	.gem_prime_mmap = drm_gem_cma_prime_mmap,
+};
+
+static int lcdc_dc_modeset_init(struct lcdc_dc *lcdc_dc, struct drm_device *drm)
+{
+	struct drm_bridge *bridge;
+	struct drm_panel *panel;
+	struct device_node *np;
+	struct device *dev;
+	int ret;
+
+	dev = drm->dev;
+
+	drm_mode_config_init(drm);
+	drm->mode_config.min_width  = lcdc_dc->desc->min_width;
+	drm->mode_config.min_height = lcdc_dc->desc->min_height;
+	drm->mode_config.max_width  = lcdc_dc->desc->max_width;
+	drm->mode_config.max_height = lcdc_dc->desc->max_height;
+	drm->mode_config.funcs	    = &mode_config_funcs;
+
+	np = dev->of_node;
+	/* port@0 is the output port */
+	ret = drm_of_find_panel_or_bridge(np, 0, 0, &panel, &bridge);
+	if (ret && ret != -ENODEV) {
+		DRM_DEV_ERROR(dev, "Failed to find panel (%d)\n", ret);
+		goto err_out;
+	}
+
+	bridge = drm_panel_bridge_add(panel, DRM_MODE_CONNECTOR_Unknown);
+	if (IS_ERR(bridge)) {
+		ret = PTR_ERR(bridge);
+		DRM_DEV_ERROR(dev, "Failed to add bridge (%d)", ret);
+		goto err_panel_remove;
+	}
+
+	lcdc_dc->panel = panel;
+	lcdc_dc->bridge = bridge;
+
+	ret = drm_simple_display_pipe_init(drm,
+					   &lcdc_dc->pipe,
+					   &lcdc_dc_display_funcs,
+					   lcdc_dc_formats,
+					   ARRAY_SIZE(lcdc_dc_formats),
+					   NULL,
+					   &lcdc_dc->connector);
+	if (ret) {
+		DRM_DEV_ERROR(dev, "Failed to init display pipe (%d)\n", ret);
+		goto err_panel_remove;
+	}
+
+	ret = drm_simple_display_pipe_attach_bridge(&lcdc_dc->pipe, bridge);
+	if (ret) {
+		DRM_DEV_ERROR(dev, "failed to attach bridge (%d)", ret);
+		goto err_panel_remove;
+	}
+
+	drm_mode_config_reset(drm);
+
+	return 0;
+
+err_panel_remove:
+	if (panel)
+		drm_panel_bridge_remove(bridge);
+
+err_out:
+	return ret;
+}
+
+static int lcdc_dc_load(struct drm_device *drm)
+{
+	const struct of_device_id *match;
+	struct platform_device *pdev;
+	struct lcdc_dc *lcdc_dc;
+	struct device *dev;
+	int ret;
+
+	dev = drm->dev;
+	pdev = to_platform_device(dev);
+
+	match = of_match_node(atmel_lcdc_of_match, dev->parent->of_node);
+	if (!match) {
+		DRM_DEV_ERROR(dev, "invalid compatible string (node=%s)",
+			      dev->parent->of_node->name);
+		return -ENODEV;
+	}
+
+	if (!match->data) {
+		DRM_DEV_ERROR(dev, "invalid lcdc_dc description\n");
+		return -EINVAL;
+	}
+
+	lcdc_dc = devm_kzalloc(dev, sizeof(*lcdc_dc), GFP_KERNEL);
+	if (!lcdc_dc) {
+		DRM_DEV_ERROR(dev, "Failed to allocate lcdc_dc\n");
+		return -ENOMEM;
+	}
+
+	/* reset of lcdc might sleep and require a preemptible task context */
+	INIT_WORK(&lcdc_dc->reset_lcdc_work, reset_lcdc_work);
+
+	platform_set_drvdata(pdev, drm);
+	dev_set_drvdata(dev, lcdc_dc);
+
+	lcdc_dc->mfd_lcdc = dev_get_drvdata(dev->parent);
+	drm->dev_private = lcdc_dc;
+
+	lcdc_dc->regmap = lcdc_dc->mfd_lcdc->regmap;
+	lcdc_dc->desc = match->data;
+	lcdc_dc->dev = dev;
+
+	lcdc_dc->lcd_supply = devm_regulator_get(dev, "lcd");
+	if (IS_ERR(lcdc_dc->lcd_supply)) {
+		DRM_DEV_ERROR(dev, "Failed to get lcd-supply (%ld)\n",
+			      PTR_ERR(lcdc_dc->lcd_supply));
+		lcdc_dc->lcd_supply = NULL;
+	}
+
+	lcdc_dc_start_clock(lcdc_dc);
+
+	pm_runtime_enable(dev);
+
+	ret = drm_vblank_init(drm, 1);
+	if (ret) {
+		DRM_DEV_ERROR(dev, "failed to initialize vblank (%d)\n",
+			      ret);
+		goto err_pm_runtime_disable;
+	}
+
+	ret = lcdc_dc_modeset_init(lcdc_dc, drm);
+	if (ret) {
+		DRM_DEV_ERROR(dev, "modeset_init failed (%d)", ret);
+		goto err_pm_runtime_disable;
+	}
+
+	pm_runtime_get_sync(dev);
+	ret = drm_irq_install(drm, lcdc_dc->mfd_lcdc->irq);
+	pm_runtime_put_sync(dev);
+	if (ret < 0) {
+		DRM_DEV_ERROR(dev, "Failed to install IRQ (%d)\n", ret);
+
+		goto err_pm_runtime_disable;
+	}
+
+	/*
+	 * Passing in 16 here will make the RGB656 mode the default
+	 * Passing in 32 will use XRGB8888 mode
+	 */
+	drm_fb_cma_fbdev_init(drm, 16, 0);
+
+	drm_kms_helper_poll_init(drm);
+
+	lcdc_dc->fbdev = drm_fbdev_cma_init(drm, 8, 1);
+	if (IS_ERR(lcdc_dc->fbdev)) {
+		ret = PTR_ERR(lcdc_dc->fbdev);
+		DRM_DEV_ERROR(dev, "Failed to init FB CMA area (%d)", ret);
+		goto err_irq_uninstall;
+	}
+
+	drm_helper_hpd_irq_event(drm);
+
+	return 0;
+
+err_irq_uninstall:
+	pm_runtime_get_sync(dev);
+	drm_irq_uninstall(drm);
+	pm_runtime_put_sync(dev);
+
+err_pm_runtime_disable:
+	pm_runtime_disable(dev);
+	lcdc_dc_stop_clock(lcdc_dc);
+
+	cancel_work_sync(&lcdc_dc->reset_lcdc_work);
+
+	return ret;
+}
+
+static void lcdc_dc_unload(struct drm_device *dev)
+{
+	struct lcdc_dc *lcdc_dc = dev->dev_private;
+
+	drm_fb_cma_fbdev_fini(dev);
+	flush_work(&lcdc_dc->reset_lcdc_work);
+	drm_kms_helper_poll_fini(dev);
+	if (lcdc_dc->panel)
+		drm_panel_bridge_remove(lcdc_dc->bridge);
+	drm_mode_config_cleanup(dev);
+
+	pm_runtime_get_sync(dev->dev);
+	drm_irq_uninstall(dev);
+	pm_runtime_put_sync(dev->dev);
+
+	dev->dev_private = NULL;
+
+	pm_runtime_disable(dev->dev);
+	lcdc_dc_stop_clock(lcdc_dc);
+	cancel_work_sync(&lcdc_dc->reset_lcdc_work);
+}
+
+
+static int lcdc_dc_probe(struct platform_device *pdev)
+{
+	struct drm_device *drm;
+	struct device *dev;
+	int ret;
+
+	dev = &pdev->dev;
+
+	drm = drm_dev_alloc(&lcdc_dc_drm_driver, dev);
+	if (IS_ERR(drm)) {
+		DRM_DEV_ERROR(dev, "Failed to allocate drm device\n");
+		return PTR_ERR(drm);
+	}
+
+	ret = lcdc_dc_load(drm);
+	if (ret)
+		goto err_put_ref;
+
+	ret = drm_dev_register(drm, 0);
+	if (ret) {
+		DRM_DEV_ERROR(dev, "Failed to register drm (%d)\n", ret);
+		goto err_unload;
+	}
+
+	return 0;
+
+err_unload:
+	lcdc_dc_unload(drm);
+
+err_put_ref:
+	drm_dev_put(drm);
+	return ret;
+}
+
+static int lcdc_dc_remove(struct platform_device *pdev)
+{
+	struct drm_device *drm;
+
+	drm = platform_get_drvdata(pdev);
+
+	drm_dev_unregister(drm);
+	lcdc_dc_unload(drm);
+	drm_dev_unref(drm);
+
+	return 0;
+}
+
+static const struct of_device_id lcdc_dc_dt_ids[] = {
+	{ .compatible = "atmel,lcdc-display-controller", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, lcdc_dc_dt_ids);
+
+static struct platform_driver lcdc_dc_driver = {
+	.probe		= lcdc_dc_probe,
+	.remove		= lcdc_dc_remove,
+	.driver		= {
+		.of_match_table = lcdc_dc_dt_ids,
+		.name	= "atmel-lcdc-dc",
+	},
+};
+
+module_platform_driver(lcdc_dc_driver);
+
+MODULE_AUTHOR("Sam Ravnborg <sam@ravnborg.org>");
+MODULE_DESCRIPTION("Atmel LCDC Display Controller DRM Driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:atmel-lcdc-dc");