drivers/video/mxsfb.c - github/trini/u-boot - Gitiles

 // SPDX-License-Identifier: GPL-2.0+
 /*
  * Freescale i.MX23/i.MX28 LCDIF driver
  *
  * Copyright (C) 2011-2013 Marek Vasut <marex@denx.de>
  */
 #include <clk.h>
 #include <dm.h>
 #include <env.h>
 #include <log.h>
 #include <asm/cache.h>
 #include <dm/device_compat.h>
 #include <linux/delay.h>
 #include <linux/errno.h>
 #include <malloc.h>
 #include <video.h>

 #include <asm/arch/clock.h>
 #include <asm/arch/imx-regs.h>
 #include <asm/arch/sys_proto.h>
 #include <asm/global_data.h>
 #include <asm/mach-imx/dma.h>
 #include <asm/io.h>

 #include "videomodes.h"

 #define	PS2KHZ(ps)	(1000000000UL / (ps))
 #define HZ2PS(hz)	(1000000000UL / ((hz) / 1000))

 #define BITS_PP		18
 #define BYTES_PP	4

 struct mxs_dma_desc desc;

 /**
  * mxsfb_system_setup() - Fine-tune LCDIF configuration
  *
  * This function is used to adjust the LCDIF configuration. This is usually
  * needed when driving the controller in System-Mode to operate an 8080 or
  * 6800 connected SmartLCD.
  */
 __weak void mxsfb_system_setup(void)
 {
 }

 /*
  * ARIES M28EVK:
  * setenv videomode
  * video=ctfb:x:800,y:480,depth:18,mode:0,pclk:30066,
  *       le:0,ri:256,up:0,lo:45,hs:1,vs:1,sync:100663296,vmode:0
  *
  * Freescale mx23evk/mx28evk with a Seiko 4.3'' WVGA panel:
  * setenv videomode
  * video=ctfb:x:800,y:480,depth:24,mode:0,pclk:29851,
  *	 le:89,ri:164,up:23,lo:10,hs:10,vs:10,sync:0,vmode:0
  */

 static void mxs_lcd_init(struct udevice *dev, u32 fb_addr,
 			 struct display_timing *timings, int bpp)
 {
 	struct mxs_lcdif_regs *regs = (struct mxs_lcdif_regs *)MXS_LCDIF_BASE;
 	const enum display_flags flags = timings->flags;
 	uint32_t word_len = 0, bus_width = 0;
 	uint8_t valid_data = 0;
 	uint32_t vdctrl0;

 #if CONFIG_IS_ENABLED(CLK)
 	struct clk clk;
 	int ret;

 	ret = clk_get_by_name(dev, "pix", &clk);
 	if (ret) {
 		dev_err(dev, "Failed to get mxs pix clk: %d\n", ret);
 		return;
 	}

 	ret = clk_set_rate(&clk, timings->pixelclock.typ);
 	if (ret < 0) {
 		dev_err(dev, "Failed to set mxs pix clk: %d\n", ret);
 		return;
 	}

 	ret = clk_enable(&clk);
 	if (ret < 0) {
 		dev_err(dev, "Failed to enable mxs pix clk: %d\n", ret);
 		return;
 	}

 	ret = clk_get_by_name(dev, "axi", &clk);
 	if (ret < 0) {
 		debug("%s: Failed to get mxs axi clk: %d\n", __func__, ret);
 	} else {
 		ret = clk_enable(&clk);
 		if (ret < 0) {
 			dev_err(dev, "Failed to enable mxs axi clk: %d\n", ret);
 			return;
 		}
 	}

 	ret = clk_get_by_name(dev, "disp_axi", &clk);
 	if (ret < 0) {
 		debug("%s: Failed to get mxs disp_axi clk: %d\n", __func__, ret);
 	} else {
 		ret = clk_enable(&clk);
 		if (ret < 0) {
 			dev_err(dev, "Failed to enable mxs disp_axi clk: %d\n", ret);
 			return;
 		}
 	}
 #else
 	/* Kick in the LCDIF clock */
 	mxs_set_lcdclk(MXS_LCDIF_BASE, timings->pixelclock.typ / 1000);
 #endif

 	/* Restart the LCDIF block */
 	mxs_reset_block(&regs->hw_lcdif_ctrl_reg);

 	switch (bpp) {
 	case 24:
 		word_len = LCDIF_CTRL_WORD_LENGTH_24BIT;
 		bus_width = LCDIF_CTRL_LCD_DATABUS_WIDTH_24BIT;
 		valid_data = 0x7;
 		break;
 	case 18:
 		word_len = LCDIF_CTRL_WORD_LENGTH_24BIT;
 		bus_width = LCDIF_CTRL_LCD_DATABUS_WIDTH_18BIT;
 		valid_data = 0x7;
 		break;
 	case 16:
 		word_len = LCDIF_CTRL_WORD_LENGTH_16BIT;
 		bus_width = LCDIF_CTRL_LCD_DATABUS_WIDTH_16BIT;
 		valid_data = 0xf;
 		break;
 	case 8:
 		word_len = LCDIF_CTRL_WORD_LENGTH_8BIT;
 		bus_width = LCDIF_CTRL_LCD_DATABUS_WIDTH_8BIT;
 		valid_data = 0xf;
 		break;
 	}

 	writel(bus_width | word_len | LCDIF_CTRL_DOTCLK_MODE |
 		LCDIF_CTRL_BYPASS_COUNT | LCDIF_CTRL_LCDIF_MASTER,
 		&regs->hw_lcdif_ctrl);

 	writel(valid_data << LCDIF_CTRL1_BYTE_PACKING_FORMAT_OFFSET,
 		&regs->hw_lcdif_ctrl1);

 	mxsfb_system_setup();

 	writel((timings->vactive.typ << LCDIF_TRANSFER_COUNT_V_COUNT_OFFSET) |
 		timings->hactive.typ, &regs->hw_lcdif_transfer_count);

 	vdctrl0 = LCDIF_VDCTRL0_ENABLE_PRESENT | LCDIF_VDCTRL0_ENABLE_POL |
 		  LCDIF_VDCTRL0_VSYNC_PERIOD_UNIT |
 		  LCDIF_VDCTRL0_VSYNC_PULSE_WIDTH_UNIT |
 		  timings->vsync_len.typ;

 	if(flags & DISPLAY_FLAGS_HSYNC_HIGH)
 		vdctrl0 |= LCDIF_VDCTRL0_HSYNC_POL;
 	if(flags & DISPLAY_FLAGS_VSYNC_HIGH)
 		vdctrl0 |= LCDIF_VDCTRL0_VSYNC_POL;
 	if(flags & DISPLAY_FLAGS_PIXDATA_NEGEDGE)
 		vdctrl0 |= LCDIF_VDCTRL0_DOTCLK_POL;
 	if(flags & DISPLAY_FLAGS_DE_HIGH)
 		vdctrl0 |= LCDIF_VDCTRL0_ENABLE_POL;

 	writel(vdctrl0, &regs->hw_lcdif_vdctrl0);
 	writel(timings->vback_porch.typ + timings->vfront_porch.typ +
 		timings->vsync_len.typ + timings->vactive.typ,
 		&regs->hw_lcdif_vdctrl1);
 	writel((timings->hsync_len.typ << LCDIF_VDCTRL2_HSYNC_PULSE_WIDTH_OFFSET) |
 		(timings->hback_porch.typ + timings->hfront_porch.typ +
 		timings->hsync_len.typ + timings->hactive.typ),
 		&regs->hw_lcdif_vdctrl2);
 	writel(((timings->hback_porch.typ + timings->hsync_len.typ) <<
 		LCDIF_VDCTRL3_HORIZONTAL_WAIT_CNT_OFFSET) |
 		(timings->vback_porch.typ + timings->vsync_len.typ),
 		&regs->hw_lcdif_vdctrl3);
 	writel((0 << LCDIF_VDCTRL4_DOTCLK_DLY_SEL_OFFSET) | timings->hactive.typ,
 		&regs->hw_lcdif_vdctrl4);

 	writel(fb_addr, &regs->hw_lcdif_cur_buf);
 	writel(fb_addr, &regs->hw_lcdif_next_buf);

 	/* Flush FIFO first */
 	writel(LCDIF_CTRL1_FIFO_CLEAR, &regs->hw_lcdif_ctrl1_set);

 #ifndef CONFIG_VIDEO_MXS_MODE_SYSTEM
 	/* Sync signals ON */
 	setbits_le32(&regs->hw_lcdif_vdctrl4, LCDIF_VDCTRL4_SYNC_SIGNALS_ON);
 #endif

 	/* FIFO cleared */
 	writel(LCDIF_CTRL1_FIFO_CLEAR, &regs->hw_lcdif_ctrl1_clr);

 	/* RUN! */
 	writel(LCDIF_CTRL_RUN, &regs->hw_lcdif_ctrl_set);
 }

 static int mxs_probe_common(struct udevice *dev, struct display_timing *timings,
 			    int bpp, u32 fb)
 {
 	/* Start framebuffer */
 	mxs_lcd_init(dev, fb, timings, bpp);

 #ifdef CONFIG_VIDEO_MXS_MODE_SYSTEM
 	/*
 	 * If the LCD runs in system mode, the LCD refresh has to be triggered
 	 * manually by setting the RUN bit in HW_LCDIF_CTRL register. To avoid
 	 * having to set this bit manually after every single change in the
 	 * framebuffer memory, we set up specially crafted circular DMA, which
 	 * sets the RUN bit, then waits until it gets cleared and repeats this
 	 * infinitelly. This way, we get smooth continuous updates of the LCD.
 	 */
 	struct mxs_lcdif_regs *regs = (struct mxs_lcdif_regs *)MXS_LCDIF_BASE;

 	memset(&desc, 0, sizeof(struct mxs_dma_desc));
 	desc.address = (dma_addr_t)&desc;
 	desc.cmd.data = MXS_DMA_DESC_COMMAND_NO_DMAXFER | MXS_DMA_DESC_CHAIN |
 			MXS_DMA_DESC_WAIT4END |
 			(1 << MXS_DMA_DESC_PIO_WORDS_OFFSET);
 	desc.cmd.pio_words[0] = readl(&regs->hw_lcdif_ctrl) | LCDIF_CTRL_RUN;
 	desc.cmd.next = (uint32_t)&desc.cmd;

 	/* Execute the DMA chain. */
 	mxs_dma_circ_start(MXS_DMA_CHANNEL_AHB_APBH_LCDIF, &desc);
 #endif

 	return 0;
 }

 static int mxs_remove_common(u32 fb)
 {
 	struct mxs_lcdif_regs *regs = (struct mxs_lcdif_regs *)MXS_LCDIF_BASE;
 	int timeout = 1000000;

 	if (!fb)
 		return -EINVAL;

 	writel(fb, &regs->hw_lcdif_cur_buf_reg);
 	writel(fb, &regs->hw_lcdif_next_buf_reg);
 	writel(LCDIF_CTRL1_VSYNC_EDGE_IRQ, &regs->hw_lcdif_ctrl1_clr);
 	while (--timeout) {
 		if (readl(&regs->hw_lcdif_ctrl1_reg) &
 		    LCDIF_CTRL1_VSYNC_EDGE_IRQ)
 			break;
 		udelay(1);
 	}
 	mxs_reset_block((struct mxs_register_32 *)&regs->hw_lcdif_ctrl_reg);

 	return 0;
 }

 static int mxs_of_get_timings(struct udevice *dev,
 			      struct display_timing *timings,
 			      u32 *bpp)
 {
 	int ret = 0;
 	u32 display_phandle;
 	ofnode display_node;

 	ret = ofnode_read_u32(dev_ofnode(dev), "display", &display_phandle);
 	if (ret) {
 		dev_err(dev, "required display property isn't provided\n");
 		return -EINVAL;
 	}

 	display_node = ofnode_get_by_phandle(display_phandle);
 	if (!ofnode_valid(display_node)) {
 		dev_err(dev, "failed to find display subnode\n");
 		return -EINVAL;
 	}

 	ret = ofnode_read_u32(display_node, "bits-per-pixel", bpp);
 	if (ret) {
 		dev_err(dev,
 			"required bits-per-pixel property isn't provided\n");
 		return -EINVAL;
 	}

 	ret = ofnode_decode_display_timing(display_node, 0, timings);
 	if (ret) {
 		dev_err(dev, "failed to get any display timings\n");
 		return -EINVAL;
 	}

 	return ret;
 }

 static int mxs_video_probe(struct udevice *dev)
 {
 	struct video_uc_plat *plat = dev_get_uclass_plat(dev);
 	struct video_priv *uc_priv = dev_get_uclass_priv(dev);

 	struct display_timing timings;
 	u32 bpp = 0;
 	u32 fb_start, fb_end;
 	int ret;

 	debug("%s() plat: base 0x%lx, size 0x%x\n",
 	       __func__, plat->base, plat->size);

 	ret = mxs_of_get_timings(dev, &timings, &bpp);
 	if (ret)
 		return ret;

 	ret = mxs_probe_common(dev, &timings, bpp, plat->base);
 	if (ret)
 		return ret;

 	switch (bpp) {
 	case 32:
 	case 24:
 	case 18:
 		uc_priv->bpix = VIDEO_BPP32;
 		break;
 	case 16:
 		uc_priv->bpix = VIDEO_BPP16;
 		break;
 	case 8:
 		uc_priv->bpix = VIDEO_BPP8;
 		break;
 	default:
 		dev_err(dev, "invalid bpp specified (bpp = %i)\n", bpp);
 		return -EINVAL;
 	}

 	uc_priv->xsize = timings.hactive.typ;
 	uc_priv->ysize = timings.vactive.typ;

 	/* Enable dcache for the frame buffer */
 	fb_start = plat->base & ~(MMU_SECTION_SIZE - 1);
 	fb_end = plat->base + plat->size;
 	fb_end = ALIGN(fb_end, 1 << MMU_SECTION_SHIFT);
 	mmu_set_region_dcache_behaviour(fb_start, fb_end - fb_start,
 					DCACHE_WRITEBACK);
 	video_set_flush_dcache(dev, true);
 	gd->fb_base = plat->base;

 	return ret;
 }

 static int mxs_video_bind(struct udevice *dev)
 {
 	struct video_uc_plat *plat = dev_get_uclass_plat(dev);
 	struct display_timing timings;
 	u32 bpp = 0;
 	u32 bytes_pp = 0;
 	int ret;

 	ret = mxs_of_get_timings(dev, &timings, &bpp);
 	if (ret)
 		return ret;

 	switch (bpp) {
 	case 32:
 	case 24:
 	case 18:
 		bytes_pp = 4;
 		break;
 	case 16:
 		bytes_pp = 2;
 		break;
 	case 8:
 		bytes_pp = 1;
 		break;
 	default:
 		dev_err(dev, "invalid bpp specified (bpp = %i)\n", bpp);
 		return -EINVAL;
 	}

 	plat->size = timings.hactive.typ * timings.vactive.typ * bytes_pp;

 	return 0;
 }

 static int mxs_video_remove(struct udevice *dev)
 {
 	struct video_uc_plat *plat = dev_get_uclass_plat(dev);

 	mxs_remove_common(plat->base);

 	return 0;
 }

 static const struct udevice_id mxs_video_ids[] = {
 	{ .compatible = "fsl,imx23-lcdif" },
 	{ .compatible = "fsl,imx28-lcdif" },
 	{ .compatible = "fsl,imx6sx-lcdif" },
 	{ .compatible = "fsl,imx7ulp-lcdif" },
 	{ .compatible = "fsl,imxrt-lcdif" },
 	{ /* sentinel */ }
 };

 U_BOOT_DRIVER(mxs_video) = {
 	.name	= "mxs_video",
 	.id	= UCLASS_VIDEO,
 	.of_match = mxs_video_ids,
 	.bind	= mxs_video_bind,
 	.probe	= mxs_video_probe,
 	.remove = mxs_video_remove,
 	.flags	= DM_FLAG_PRE_RELOC | DM_FLAG_OS_PREPARE,
 };
	// SPDX-License-Identifier: GPL-2.0+
	/*
	* Freescale i.MX23/i.MX28 LCDIF driver
	*
	* Copyright (C) 2011-2013 Marek Vasut <marex@denx.de>
	*/
	#include <clk.h>
	#include <dm.h>
	#include <env.h>
	#include <log.h>
	#include <asm/cache.h>
	#include <dm/device_compat.h>
	#include <linux/delay.h>
	#include <linux/errno.h>
	#include <malloc.h>
	#include <video.h>

	#include <asm/arch/clock.h>
	#include <asm/arch/imx-regs.h>
	#include <asm/arch/sys_proto.h>
	#include <asm/global_data.h>
	#include <asm/mach-imx/dma.h>
	#include <asm/io.h>

	#include "videomodes.h"

	#define PS2KHZ(ps) (1000000000UL / (ps))
	#define HZ2PS(hz) (1000000000UL / ((hz) / 1000))

	#define BITS_PP 18
	#define BYTES_PP 4

	struct mxs_dma_desc desc;

	/**
	* mxsfb_system_setup() - Fine-tune LCDIF configuration
	*
	* This function is used to adjust the LCDIF configuration. This is usually
	* needed when driving the controller in System-Mode to operate an 8080 or
	* 6800 connected SmartLCD.
	*/
	__weak void mxsfb_system_setup(void)
	{
	}

	/*
	* ARIES M28EVK:
	* setenv videomode
	* video=ctfb:x:800,y:480,depth:18,mode:0,pclk:30066,
	* le:0,ri:256,up:0,lo:45,hs:1,vs:1,sync:100663296,vmode:0
	*
	* Freescale mx23evk/mx28evk with a Seiko 4.3'' WVGA panel:
	* setenv videomode
	* video=ctfb:x:800,y:480,depth:24,mode:0,pclk:29851,
	* le:89,ri:164,up:23,lo:10,hs:10,vs:10,sync:0,vmode:0
	*/

	static void mxs_lcd_init(struct udevice *dev, u32 fb_addr,
	struct display_timing *timings, int bpp)
	{
	struct mxs_lcdif_regs regs = (struct mxs_lcdif_regs )MXS_LCDIF_BASE;
	const enum display_flags flags = timings->flags;
	uint32_t word_len = 0, bus_width = 0;
	uint8_t valid_data = 0;
	uint32_t vdctrl0;

	#if CONFIG_IS_ENABLED(CLK)
	struct clk clk;
	int ret;

	ret = clk_get_by_name(dev, "pix", &clk);
	if (ret) {
	dev_err(dev, "Failed to get mxs pix clk: %d\n", ret);
	return;
	}

	ret = clk_set_rate(&clk, timings->pixelclock.typ);
	if (ret < 0) {
	dev_err(dev, "Failed to set mxs pix clk: %d\n", ret);
	return;
	}

	ret = clk_enable(&clk);
	if (ret < 0) {
	dev_err(dev, "Failed to enable mxs pix clk: %d\n", ret);
	return;
	}

	ret = clk_get_by_name(dev, "axi", &clk);
	if (ret < 0) {
	debug("%s: Failed to get mxs axi clk: %d\n", __func__, ret);
	} else {
	ret = clk_enable(&clk);
	if (ret < 0) {
	dev_err(dev, "Failed to enable mxs axi clk: %d\n", ret);
	return;
	}
	}

	ret = clk_get_by_name(dev, "disp_axi", &clk);
	if (ret < 0) {
	debug("%s: Failed to get mxs disp_axi clk: %d\n", __func__, ret);
	} else {
	ret = clk_enable(&clk);
	if (ret < 0) {
	dev_err(dev, "Failed to enable mxs disp_axi clk: %d\n", ret);
	return;
	}
	}
	#else
	/* Kick in the LCDIF clock */
	mxs_set_lcdclk(MXS_LCDIF_BASE, timings->pixelclock.typ / 1000);
	#endif

	/* Restart the LCDIF block */
	mxs_reset_block(&regs->hw_lcdif_ctrl_reg);

	switch (bpp) {
	case 24:
	word_len = LCDIF_CTRL_WORD_LENGTH_24BIT;
	bus_width = LCDIF_CTRL_LCD_DATABUS_WIDTH_24BIT;
	valid_data = 0x7;
	break;
	case 18:
	word_len = LCDIF_CTRL_WORD_LENGTH_24BIT;
	bus_width = LCDIF_CTRL_LCD_DATABUS_WIDTH_18BIT;
	valid_data = 0x7;
	break;
	case 16:
	word_len = LCDIF_CTRL_WORD_LENGTH_16BIT;
	bus_width = LCDIF_CTRL_LCD_DATABUS_WIDTH_16BIT;
	valid_data = 0xf;
	break;
	case 8:
	word_len = LCDIF_CTRL_WORD_LENGTH_8BIT;
	bus_width = LCDIF_CTRL_LCD_DATABUS_WIDTH_8BIT;
	valid_data = 0xf;
	break;
	}

	writel(bus_width \| word_len \| LCDIF_CTRL_DOTCLK_MODE \|
	LCDIF_CTRL_BYPASS_COUNT \| LCDIF_CTRL_LCDIF_MASTER,
	&regs->hw_lcdif_ctrl);

	writel(valid_data << LCDIF_CTRL1_BYTE_PACKING_FORMAT_OFFSET,
	&regs->hw_lcdif_ctrl1);

	mxsfb_system_setup();

	writel((timings->vactive.typ << LCDIF_TRANSFER_COUNT_V_COUNT_OFFSET) \|
	timings->hactive.typ, &regs->hw_lcdif_transfer_count);

	vdctrl0 = LCDIF_VDCTRL0_ENABLE_PRESENT \| LCDIF_VDCTRL0_ENABLE_POL \|
	LCDIF_VDCTRL0_VSYNC_PERIOD_UNIT \|
	LCDIF_VDCTRL0_VSYNC_PULSE_WIDTH_UNIT \|
	timings->vsync_len.typ;

	if(flags & DISPLAY_FLAGS_HSYNC_HIGH)
	vdctrl0 \|= LCDIF_VDCTRL0_HSYNC_POL;
	if(flags & DISPLAY_FLAGS_VSYNC_HIGH)
	vdctrl0 \|= LCDIF_VDCTRL0_VSYNC_POL;
	if(flags & DISPLAY_FLAGS_PIXDATA_NEGEDGE)
	vdctrl0 \|= LCDIF_VDCTRL0_DOTCLK_POL;
	if(flags & DISPLAY_FLAGS_DE_HIGH)
	vdctrl0 \|= LCDIF_VDCTRL0_ENABLE_POL;

	writel(vdctrl0, &regs->hw_lcdif_vdctrl0);
	writel(timings->vback_porch.typ + timings->vfront_porch.typ +
	timings->vsync_len.typ + timings->vactive.typ,
	&regs->hw_lcdif_vdctrl1);
	writel((timings->hsync_len.typ << LCDIF_VDCTRL2_HSYNC_PULSE_WIDTH_OFFSET) \|
	(timings->hback_porch.typ + timings->hfront_porch.typ +
	timings->hsync_len.typ + timings->hactive.typ),
	&regs->hw_lcdif_vdctrl2);
	writel(((timings->hback_porch.typ + timings->hsync_len.typ) <<
	LCDIF_VDCTRL3_HORIZONTAL_WAIT_CNT_OFFSET) \|
	(timings->vback_porch.typ + timings->vsync_len.typ),
	&regs->hw_lcdif_vdctrl3);
	writel((0 << LCDIF_VDCTRL4_DOTCLK_DLY_SEL_OFFSET) \| timings->hactive.typ,
	&regs->hw_lcdif_vdctrl4);

	writel(fb_addr, &regs->hw_lcdif_cur_buf);
	writel(fb_addr, &regs->hw_lcdif_next_buf);

	/* Flush FIFO first */
	writel(LCDIF_CTRL1_FIFO_CLEAR, &regs->hw_lcdif_ctrl1_set);

	#ifndef CONFIG_VIDEO_MXS_MODE_SYSTEM
	/* Sync signals ON */
	setbits_le32(&regs->hw_lcdif_vdctrl4, LCDIF_VDCTRL4_SYNC_SIGNALS_ON);
	#endif

	/* FIFO cleared */
	writel(LCDIF_CTRL1_FIFO_CLEAR, &regs->hw_lcdif_ctrl1_clr);

	/* RUN! */
	writel(LCDIF_CTRL_RUN, &regs->hw_lcdif_ctrl_set);
	}

	static int mxs_probe_common(struct udevice dev, struct display_timing timings,
	int bpp, u32 fb)
	{
	/* Start framebuffer */
	mxs_lcd_init(dev, fb, timings, bpp);

	#ifdef CONFIG_VIDEO_MXS_MODE_SYSTEM
	/*
	* If the LCD runs in system mode, the LCD refresh has to be triggered
	* manually by setting the RUN bit in HW_LCDIF_CTRL register. To avoid
	* having to set this bit manually after every single change in the
	* framebuffer memory, we set up specially crafted circular DMA, which
	* sets the RUN bit, then waits until it gets cleared and repeats this
	* infinitelly. This way, we get smooth continuous updates of the LCD.
	*/
	struct mxs_lcdif_regs regs = (struct mxs_lcdif_regs )MXS_LCDIF_BASE;

	memset(&desc, 0, sizeof(struct mxs_dma_desc));
	desc.address = (dma_addr_t)&desc;
	desc.cmd.data = MXS_DMA_DESC_COMMAND_NO_DMAXFER \| MXS_DMA_DESC_CHAIN \|
	MXS_DMA_DESC_WAIT4END \|
	(1 << MXS_DMA_DESC_PIO_WORDS_OFFSET);
	desc.cmd.pio_words[0] = readl(&regs->hw_lcdif_ctrl) \| LCDIF_CTRL_RUN;
	desc.cmd.next = (uint32_t)&desc.cmd;

	/* Execute the DMA chain. */
	mxs_dma_circ_start(MXS_DMA_CHANNEL_AHB_APBH_LCDIF, &desc);
	#endif

	return 0;
	}

	static int mxs_remove_common(u32 fb)
	{
	struct mxs_lcdif_regs regs = (struct mxs_lcdif_regs )MXS_LCDIF_BASE;
	int timeout = 1000000;

	if (!fb)
	return -EINVAL;

	writel(fb, &regs->hw_lcdif_cur_buf_reg);
	writel(fb, &regs->hw_lcdif_next_buf_reg);
	writel(LCDIF_CTRL1_VSYNC_EDGE_IRQ, &regs->hw_lcdif_ctrl1_clr);
	while (--timeout) {
	if (readl(&regs->hw_lcdif_ctrl1_reg) &
	LCDIF_CTRL1_VSYNC_EDGE_IRQ)
	break;
	udelay(1);
	}
	mxs_reset_block((struct mxs_register_32 *)&regs->hw_lcdif_ctrl_reg);

	return 0;
	}

	static int mxs_of_get_timings(struct udevice *dev,
	struct display_timing *timings,
	u32 *bpp)
	{
	int ret = 0;
	u32 display_phandle;
	ofnode display_node;

	ret = ofnode_read_u32(dev_ofnode(dev), "display", &display_phandle);
	if (ret) {
	dev_err(dev, "required display property isn't provided\n");
	return -EINVAL;
	}

	display_node = ofnode_get_by_phandle(display_phandle);
	if (!ofnode_valid(display_node)) {
	dev_err(dev, "failed to find display subnode\n");
	return -EINVAL;
	}

	ret = ofnode_read_u32(display_node, "bits-per-pixel", bpp);
	if (ret) {
	dev_err(dev,
	"required bits-per-pixel property isn't provided\n");
	return -EINVAL;
	}

	ret = ofnode_decode_display_timing(display_node, 0, timings);
	if (ret) {
	dev_err(dev, "failed to get any display timings\n");
	return -EINVAL;
	}

	return ret;
	}

	static int mxs_video_probe(struct udevice *dev)
	{
	struct video_uc_plat *plat = dev_get_uclass_plat(dev);
	struct video_priv *uc_priv = dev_get_uclass_priv(dev);

	struct display_timing timings;
	u32 bpp = 0;
	u32 fb_start, fb_end;
	int ret;

	debug("%s() plat: base 0x%lx, size 0x%x\n",
	__func__, plat->base, plat->size);

	ret = mxs_of_get_timings(dev, &timings, &bpp);
	if (ret)
	return ret;

	ret = mxs_probe_common(dev, &timings, bpp, plat->base);
	if (ret)
	return ret;

	switch (bpp) {
	case 32:
	case 24:
	case 18:
	uc_priv->bpix = VIDEO_BPP32;
	break;
	case 16:
	uc_priv->bpix = VIDEO_BPP16;
	break;
	case 8:
	uc_priv->bpix = VIDEO_BPP8;
	break;
	default:
	dev_err(dev, "invalid bpp specified (bpp = %i)\n", bpp);
	return -EINVAL;
	}

	uc_priv->xsize = timings.hactive.typ;
	uc_priv->ysize = timings.vactive.typ;

	/* Enable dcache for the frame buffer */
	fb_start = plat->base & ~(MMU_SECTION_SIZE - 1);
	fb_end = plat->base + plat->size;
	fb_end = ALIGN(fb_end, 1 << MMU_SECTION_SHIFT);
	mmu_set_region_dcache_behaviour(fb_start, fb_end - fb_start,
	DCACHE_WRITEBACK);
	video_set_flush_dcache(dev, true);
	gd->fb_base = plat->base;

	return ret;
	}

	static int mxs_video_bind(struct udevice *dev)
	{
	struct video_uc_plat *plat = dev_get_uclass_plat(dev);
	struct display_timing timings;
	u32 bpp = 0;
	u32 bytes_pp = 0;
	int ret;

	ret = mxs_of_get_timings(dev, &timings, &bpp);
	if (ret)
	return ret;

	switch (bpp) {
	case 32:
	case 24:
	case 18:
	bytes_pp = 4;
	break;
	case 16:
	bytes_pp = 2;
	break;
	case 8:
	bytes_pp = 1;
	break;
	default:
	dev_err(dev, "invalid bpp specified (bpp = %i)\n", bpp);
	return -EINVAL;
	}

	plat->size = timings.hactive.typ * timings.vactive.typ * bytes_pp;

	return 0;
	}

	static int mxs_video_remove(struct udevice *dev)
	{
	struct video_uc_plat *plat = dev_get_uclass_plat(dev);

	mxs_remove_common(plat->base);

	return 0;
	}

	static const struct udevice_id mxs_video_ids[] = {
	{ .compatible = "fsl,imx23-lcdif" },
	{ .compatible = "fsl,imx28-lcdif" },
	{ .compatible = "fsl,imx6sx-lcdif" },
	{ .compatible = "fsl,imx7ulp-lcdif" },
	{ .compatible = "fsl,imxrt-lcdif" },
	{ /* sentinel */ }
	};

	U_BOOT_DRIVER(mxs_video) = {
	.name = "mxs_video",
	.id = UCLASS_VIDEO,
	.of_match = mxs_video_ids,
	.bind = mxs_video_bind,
	.probe = mxs_video_probe,
	.remove = mxs_video_remove,
	.flags = DM_FLAG_PRE_RELOC \| DM_FLAG_OS_PREPARE,
	};