drivers/video/stm32/stm32_ltdc.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright (C) 2017-2018 STMicroelectronics - All Rights Reserved
 * Author(s): Philippe Cornu <philippe.cornu@st.com> for STMicroelectronics.
 *	      Yannick Fertre <yannick.fertre@st.com> for STMicroelectronics.
 */

#define LOG_CATEGORY UCLASS_VIDEO

#include <clk.h>
#include <display.h>
#include <dm.h>
#include <log.h>
#include <panel.h>
#include <reset.h>
#include <video.h>
#include <video_bridge.h>
#include <asm/io.h>
#include <dm/device-internal.h>
#include <dm/device_compat.h>
#include <linux/bitops.h>
#include <linux/printk.h>

struct stm32_ltdc_priv {
	void __iomem *regs;
	enum video_log2_bpp l2bpp;
	u32 bg_col_argb;
	const u32 *layer_regs;
	const u32 *pix_fmt_hw;
	u32 crop_x, crop_y, crop_w, crop_h;
	u32 alpha;
	u32 hw_version;
};

/* Layer register offsets */
static const u32 layer_regs_a0[] = {
	0x80,	/* L1 configuration 0 */
	0x00,	/* not available */
	0x00,	/* not available */
	0x84,	/* L1 control register */
	0x88,	/* L1 window horizontal position configuration */
	0x8c,	/* L1 window vertical position configuration */
	0x90,	/* L1 color keying configuration */
	0x94,	/* L1 pixel format configuration */
	0x98,	/* L1 constant alpha configuration */
	0x9c,	/* L1 default color configuration */
	0xa0,	/* L1 blending factors configuration */
	0x00,	/* not available */
	0x00,	/* not available */
	0xac,	/* L1 color frame buffer address */
	0xb0,	/* L1 color frame buffer length */
	0xb4,	/* L1 color frame buffer line number */
	0x00,	/* not available */
	0x00,	/* not available */
	0x00,	/* not available */
	0x00,	/* not available */
	0xc4,	/* L1 CLUT write */
	0x00,	/* not available */
	0x00,	/* not available */
	0x00,	/* not available */
	0x00,	/* not available */
	0x00,	/* not available */
	0x00,	/* not available */
	0x00,	/* not available */
	0x00,	/* not available */
	0x00,	/* not available */
	0x00	/* not available */
};

static const u32 layer_regs_a1[] = {
	0x80,	/* L1 configuration 0 */
	0x84,	/* L1 configuration 1 */
	0x00,	/* L1 reload control */
	0x88,	/* L1 control register */
	0x8c,	/* L1 window horizontal position configuration */
	0x90,	/* L1 window vertical position configuration */
	0x94,	/* L1 color keying configuration */
	0x98,	/* L1 pixel format configuration */
	0x9c,	/* L1 constant alpha configuration */
	0xa0,	/* L1 default color configuration */
	0xa4,	/* L1 blending factors configuration */
	0xa8,	/* L1 burst length configuration */
	0x00,	/* not available */
	0xac,	/* L1 color frame buffer address */
	0xb0,	/* L1 color frame buffer length */
	0xb4,	/* L1 color frame buffer line number */
	0xb8,	/* L1 auxiliary frame buffer address 0 */
	0xbc,	/* L1 auxiliary frame buffer address 1 */
	0xc0,	/* L1 auxiliary frame buffer length */
	0xc4,	/* L1 auxiliary frame buffer line number */
	0xc8,	/* L1 CLUT write */
	0x00,	/* not available */
	0x00,	/* not available */
	0x00,	/* not available */
	0x00,	/* not available */
	0x00,	/* not available */
	0x00,	/* not available */
	0x00,	/* not available */
	0x00,	/* not available */
	0x00,	/* not available */
	0x00	/* not available */
};

static const u32 layer_regs_a2[] = {
	0x100,	/* L1 configuration 0 */
	0x104,	/* L1 configuration 1 */
	0x108,	/* L1 reload control */
	0x10c,	/* L1 control register */
	0x110,	/* L1 window horizontal position configuration */
	0x114,	/* L1 window vertical position configuration */
	0x118,	/* L1 color keying configuration */
	0x11c,	/* L1 pixel format configuration */
	0x120,	/* L1 constant alpha configuration */
	0x124,	/* L1 default color configuration */
	0x128,	/* L1 blending factors configuration */
	0x12c,	/* L1 burst length configuration */
	0x130,	/* L1 planar configuration */
	0x134,	/* L1 color frame buffer address */
	0x138,	/* L1 color frame buffer length */
	0x13c,	/* L1 color frame buffer line number */
	0x140,	/* L1 auxiliary frame buffer address 0 */
	0x144,	/* L1 auxiliary frame buffer address 1 */
	0x148,	/* L1 auxiliary frame buffer length */
	0x14c,	/* L1 auxiliary frame buffer line number */
	0x150,	/* L1 CLUT write */
	0x154,	/* not available */
	0x158,	/* not available */
	0x15c,	/* not available */
	0x160,	/* not available */
	0x164,	/* not available */
	0x168,	/* not available */
	0x16c,	/* L1 Conversion YCbCr RGB 0 */
	0x170,	/* L1 Conversion YCbCr RGB 1 */
	0x174,	/* L1 Flexible Pixel Format 0 */
	0x178	/* L1 Flexible Pixel Format 1 */
};

/* LTDC main registers */
#define LTDC_IDR	0x00	/* IDentification */
#define LTDC_LCR	0x04	/* Layer Count */
#define LTDC_SSCR	0x08	/* Synchronization Size Configuration */
#define LTDC_BPCR	0x0C	/* Back Porch Configuration */
#define LTDC_AWCR	0x10	/* Active Width Configuration */
#define LTDC_TWCR	0x14	/* Total Width Configuration */
#define LTDC_GCR	0x18	/* Global Control */
#define LTDC_GC1R	0x1C	/* Global Configuration 1 */
#define LTDC_GC2R	0x20	/* Global Configuration 2 */
#define LTDC_SRCR	0x24	/* Shadow Reload Configuration */
#define LTDC_GACR	0x28	/* GAmma Correction */
#define LTDC_BCCR	0x2C	/* Background Color Configuration */
#define LTDC_IER	0x34	/* Interrupt Enable */
#define LTDC_ISR	0x38	/* Interrupt Status */
#define LTDC_ICR	0x3C	/* Interrupt Clear */
#define LTDC_LIPCR	0x40	/* Line Interrupt Position Conf. */
#define LTDC_CPSR	0x44	/* Current Position Status */
#define LTDC_CDSR	0x48	/* Current Display Status */

/* Layer register offsets */
#define LTDC_L1C0R	(priv->layer_regs[0])	/* L1 configuration 0 */
#define LTDC_L1C1R	(priv->layer_regs[1])	/* L1 configuration 1 */
#define LTDC_L1RCR	(priv->layer_regs[2])	/* L1 reload control */
#define LTDC_L1CR	(priv->layer_regs[3])	/* L1 control register */
#define LTDC_L1WHPCR	(priv->layer_regs[4])	/* L1 window horizontal position configuration */
#define LTDC_L1WVPCR	(priv->layer_regs[5])	/* L1 window vertical position configuration */
#define LTDC_L1CKCR	(priv->layer_regs[6])	/* L1 color keying configuration */
#define LTDC_L1PFCR	(priv->layer_regs[7])	/* L1 pixel format configuration */
#define LTDC_L1CACR	(priv->layer_regs[8])	/* L1 constant alpha configuration */
#define LTDC_L1DCCR	(priv->layer_regs[9])	/* L1 default color configuration */
#define LTDC_L1BFCR	(priv->layer_regs[10])	/* L1 blending factors configuration */
#define LTDC_L1BLCR	(priv->layer_regs[11])	/* L1 burst length configuration */
#define LTDC_L1PCR	(priv->layer_regs[12])	/* L1 planar configuration */
#define LTDC_L1CFBAR	(priv->layer_regs[13])	/* L1 color frame buffer address */
#define LTDC_L1CFBLR	(priv->layer_regs[14])	/* L1 color frame buffer length */
#define LTDC_L1CFBLNR	(priv->layer_regs[15])	/* L1 color frame buffer line number */
#define LTDC_L1AFBA0R	(priv->layer_regs[16])	/* L1 auxiliary frame buffer address 0 */
#define LTDC_L1AFBA1R	(priv->layer_regs[17])	/* L1 auxiliary frame buffer address 1 */
#define LTDC_L1AFBLR	(priv->layer_regs[18])	/* L1 auxiliary frame buffer length */
#define LTDC_L1AFBLNR	(priv->layer_regs[19])	/* L1 auxiliary frame buffer line number */
#define LTDC_L1CLUTWR	(priv->layer_regs[20])	/* L1 CLUT write */
#define LTDC_L1CYR0R	(priv->layer_regs[27])	/* L1 Conversion YCbCr RGB 0 */
#define LTDC_L1CYR1R	(priv->layer_regs[28])	/* L1 Conversion YCbCr RGB 1 */
#define LTDC_L1FPF0R	(priv->layer_regs[29])	/* L1 Flexible Pixel Format 0 */
#define LTDC_L1FPF1R	(priv->layer_regs[30])	/* L1 Flexible Pixel Format 1 */

/* Bit definitions */
#define SSCR_VSH	GENMASK(10, 0)	/* Vertical Synchronization Height */
#define SSCR_HSW	GENMASK(27, 16)	/* Horizontal Synchronization Width */

#define BPCR_AVBP	GENMASK(10, 0)	/* Accumulated Vertical Back Porch */
#define BPCR_AHBP	GENMASK(27, 16)	/* Accumulated Horizontal Back Porch */

#define AWCR_AAH	GENMASK(10, 0)	/* Accumulated Active Height */
#define AWCR_AAW	GENMASK(27, 16)	/* Accumulated Active Width */

#define TWCR_TOTALH	GENMASK(10, 0)	/* TOTAL Height */
#define TWCR_TOTALW	GENMASK(27, 16)	/* TOTAL Width */

#define GCR_LTDCEN	BIT(0)		/* LTDC ENable */
#define GCR_DEN		BIT(16)		/* Dither ENable */
#define GCR_PCPOL	BIT(28)		/* Pixel Clock POLarity-Inverted */
#define GCR_DEPOL	BIT(29)		/* Data Enable POLarity-High */
#define GCR_VSPOL	BIT(30)		/* Vertical Synchro POLarity-High */
#define GCR_HSPOL	BIT(31)		/* Horizontal Synchro POLarity-High */

#define GC1R_WBCH	GENMASK(3, 0)	/* Width of Blue CHannel output */
#define GC1R_WGCH	GENMASK(7, 4)	/* Width of Green Channel output */
#define GC1R_WRCH	GENMASK(11, 8)	/* Width of Red Channel output */
#define GC1R_PBEN	BIT(12)		/* Precise Blending ENable */
#define GC1R_DT		GENMASK(15, 14)	/* Dithering Technique */
#define GC1R_GCT	GENMASK(19, 17)	/* Gamma Correction Technique */
#define GC1R_SHREN	BIT(21)		/* SHadow Registers ENabled */
#define GC1R_BCP	BIT(22)		/* Background Colour Programmable */
#define GC1R_BBEN	BIT(23)		/* Background Blending ENabled */
#define GC1R_LNIP	BIT(24)		/* Line Number IRQ Position */
#define GC1R_TP		BIT(25)		/* Timing Programmable */
#define GC1R_IPP	BIT(26)		/* IRQ Polarity Programmable */
#define GC1R_SPP	BIT(27)		/* Sync Polarity Programmable */
#define GC1R_DWP	BIT(28)		/* Dither Width Programmable */
#define GC1R_STREN	BIT(29)		/* STatus Registers ENabled */
#define GC1R_BMEN	BIT(31)		/* Blind Mode ENabled */

#define GC2R_EDCA	BIT(0)		/* External Display Control Ability  */
#define GC2R_STSAEN	BIT(1)		/* Slave Timing Sync Ability ENabled */
#define GC2R_DVAEN	BIT(2)		/* Dual-View Ability ENabled */
#define GC2R_DPAEN	BIT(3)		/* Dual-Port Ability ENabled */
#define GC2R_BW		GENMASK(6, 4)	/* Bus Width (log2 of nb of bytes) */
#define GC2R_EDCEN	BIT(7)		/* External Display Control ENabled */

#define SRCR_IMR	BIT(0)		/* IMmediate Reload */
#define SRCR_VBR	BIT(1)		/* Vertical Blanking Reload */

#define LXCR_LEN	BIT(0)		/* Layer ENable */
#define LXCR_COLKEN	BIT(1)		/* Color Keying Enable */
#define LXCR_CLUTEN	BIT(4)		/* Color Look-Up Table ENable */

#define LXWHPCR_WHSTPOS	GENMASK(11, 0)	/* Window Horizontal StarT POSition */
#define LXWHPCR_WHSPPOS	GENMASK(27, 16)	/* Window Horizontal StoP POSition */

#define LXWVPCR_WVSTPOS	GENMASK(10, 0)	/* Window Vertical StarT POSition */
#define LXWVPCR_WVSPPOS	GENMASK(26, 16)	/* Window Vertical StoP POSition */

#define LXPFCR_PF	GENMASK(2, 0)	/* Pixel Format */

#define LXCACR_CONSTA	GENMASK(7, 0)	/* CONSTant Alpha */

#define LXBFCR_BF2	GENMASK(2, 0)	/* Blending Factor 2 */
#define LXBFCR_BF1	GENMASK(10, 8)	/* Blending Factor 1 */

#define LXCFBLR_CFBLL	GENMASK(12, 0)	/* Color Frame Buffer Line Length */
#define LXCFBLR_CFBP	GENMASK(28, 16)	/* Color Frame Buffer Pitch in bytes */

#define LXCFBLNR_CFBLN	GENMASK(10, 0)	/* Color Frame Buffer Line Number */

#define BF1_PAXCA	0x600		/* Pixel Alpha x Constant Alpha */
#define BF1_CA		0x400		/* Constant Alpha */
#define BF2_1PAXCA	0x007		/* 1 - (Pixel Alpha x Constant Alpha) */
#define BF2_1CA		0x005		/* 1 - Constant Alpha */

#define NB_PF		8		/* Max nb of HW pixel format */

#define HWVER_10200 0x010200
#define HWVER_10300 0x010300
#define HWVER_20101 0x020101
#define HWVER_40100 0x040100

enum stm32_ltdc_pix_fmt {
	PF_ARGB8888 = 0,	/* ARGB [32 bits] */
	PF_ABGR8888,		/* ABGR [32 bits] */
	PF_BGRA8888,		/* BGRA [32 bits] */
	PF_RGBA8888,		/* RGBA [32 bits] */
	PF_RGB888,		/* RGB [24 bits] */
	PF_BGR565,		/* RGB [16 bits] */
	PF_RGB565,		/* RGB [16 bits] */
	PF_ARGB1555,		/* ARGB A:1 bit RGB:15 bits [16 bits] */
	PF_ARGB4444,		/* ARGB A:4 bits R/G/B: 4 bits each [16 bits] */
	PF_AL44,		/* Alpha:4 bits + indexed 4 bits [8 bits] */
	PF_AL88,		/* Alpha:8 bits + indexed 8 bits [16 bits] */
	PF_L8,			/* Indexed 8 bits [8 bits] */
	PF_NONE
};

static const enum stm32_ltdc_pix_fmt pix_fmt_a0[NB_PF] = {
	PF_ARGB8888,		/* 0x00 */
	PF_RGB888,		/* 0x01 */
	PF_RGB565,		/* 0x02 */
	PF_ARGB1555,		/* 0x03 */
	PF_ARGB4444,		/* 0x04 */
	PF_L8,			/* 0x05 */
	PF_AL44,		/* 0x06 */
	PF_AL88			/* 0x07 */
};

static const enum stm32_ltdc_pix_fmt pix_fmt_a1[NB_PF] = {
	PF_ARGB8888,		/* 0x00 */
	PF_RGB888,		/* 0x01 */
	PF_RGB565,		/* 0x02 */
	PF_RGBA8888,		/* 0x03 */
	PF_AL44,		/* 0x04 */
	PF_L8,			/* 0x05 */
	PF_ARGB1555,		/* 0x06 */
	PF_ARGB4444		/* 0x07 */
};

static const enum stm32_ltdc_pix_fmt pix_fmt_a2[NB_PF] = {
	PF_ARGB8888,		/* 0x00 */
	PF_ABGR8888,		/* 0x01 */
	PF_RGBA8888,		/* 0x02 */
	PF_BGRA8888,		/* 0x03 */
	PF_RGB565,		/* 0x04 */
	PF_BGR565,		/* 0x05 */
	PF_RGB888,		/* 0x06 */
	PF_NONE			/* 0x07 (flexible pixel format) */
};

/* TODO add more color format support */
static u32 stm32_ltdc_get_pixel_format(enum video_log2_bpp l2bpp)
{
	enum stm32_ltdc_pix_fmt pf;

	switch (l2bpp) {
	case VIDEO_BPP16:
		pf = PF_RGB565;
		break;

	case VIDEO_BPP32:
		pf = PF_ARGB8888;
		break;

	case VIDEO_BPP8:
		pf = PF_L8;
		break;

	case VIDEO_BPP1:
	case VIDEO_BPP2:
	case VIDEO_BPP4:
	default:
		log_warning("warning %dbpp not supported yet, %dbpp instead\n",
			    VNBITS(l2bpp), VNBITS(VIDEO_BPP16));
		pf = PF_RGB565;
		break;
	}

	log_debug("%d bpp -> ltdc pf %d\n", VNBITS(l2bpp), pf);

	return (u32)pf;
}

static bool has_alpha(u32 fmt)
{
	switch (fmt) {
	case PF_ARGB8888:
	case PF_ARGB1555:
	case PF_ARGB4444:
	case PF_AL44:
	case PF_AL88:
		return true;
	case PF_RGB888:
	case PF_RGB565:
	case PF_L8:
	default:
		return false;
	}
}

static void stm32_ltdc_enable(struct stm32_ltdc_priv *priv)
{
	/* Reload configuration immediately & enable LTDC */
	setbits_le32(priv->regs + LTDC_SRCR, SRCR_IMR);
	setbits_le32(priv->regs + LTDC_GCR, GCR_LTDCEN);
}

static void stm32_ltdc_set_mode(struct stm32_ltdc_priv *priv,
				struct display_timing *timings)
{
	void __iomem *regs = priv->regs;
	u32 hsync, vsync, acc_hbp, acc_vbp, acc_act_w, acc_act_h;
	u32 total_w, total_h;
	u32 val;

	/* Convert video timings to ltdc timings */
	hsync = timings->hsync_len.typ - 1;
	vsync = timings->vsync_len.typ - 1;
	acc_hbp = hsync + timings->hback_porch.typ;
	acc_vbp = vsync + timings->vback_porch.typ;
	acc_act_w = acc_hbp + timings->hactive.typ;
	acc_act_h = acc_vbp + timings->vactive.typ;
	total_w = acc_act_w + timings->hfront_porch.typ;
	total_h = acc_act_h + timings->vfront_porch.typ;

	/* Synchronization sizes */
	val = (hsync << 16) | vsync;
	clrsetbits_le32(regs + LTDC_SSCR, SSCR_VSH | SSCR_HSW, val);

	/* Accumulated back porch */
	val = (acc_hbp << 16) | acc_vbp;
	clrsetbits_le32(regs + LTDC_BPCR, BPCR_AVBP | BPCR_AHBP, val);

	/* Accumulated active width */
	val = (acc_act_w << 16) | acc_act_h;
	clrsetbits_le32(regs + LTDC_AWCR, AWCR_AAW | AWCR_AAH, val);

	/* Total width & height */
	val = (total_w << 16) | total_h;
	clrsetbits_le32(regs + LTDC_TWCR, TWCR_TOTALH | TWCR_TOTALW, val);

	setbits_le32(regs + LTDC_LIPCR, acc_act_h + 1);

	/* Signal polarities */
	val = 0;
	log_debug("timing->flags 0x%08x\n", timings->flags);
	if (timings->flags & DISPLAY_FLAGS_HSYNC_HIGH)
		val |= GCR_HSPOL;
	if (timings->flags & DISPLAY_FLAGS_VSYNC_HIGH)
		val |= GCR_VSPOL;
	if (timings->flags & DISPLAY_FLAGS_DE_LOW)
		val |= GCR_DEPOL;
	if (timings->flags & DISPLAY_FLAGS_PIXDATA_NEGEDGE)
		val |= GCR_PCPOL;
	clrsetbits_le32(regs + LTDC_GCR,
			GCR_HSPOL | GCR_VSPOL | GCR_DEPOL | GCR_PCPOL, val);

	/* Overall background color */
	writel(priv->bg_col_argb, priv->regs + LTDC_BCCR);
}

static void stm32_ltdc_set_layer1(struct stm32_ltdc_priv *priv, ulong fb_addr)
{
	void __iomem *regs = priv->regs;
	u32 x0, x1, y0, y1;
	u32 pitch_in_bytes;
	u32 line_length;
	u32 bus_width;
	u32 val, tmp, bpp;
	u32 format;

	x0 = priv->crop_x;
	x1 = priv->crop_x + priv->crop_w - 1;
	y0 = priv->crop_y;
	y1 = priv->crop_y + priv->crop_h - 1;

	/* Horizontal start and stop position */
	tmp = (readl(regs + LTDC_BPCR) & BPCR_AHBP) >> 16;
	val = ((x1 + 1 + tmp) << 16) + (x0 + 1 + tmp);
	clrsetbits_le32(regs + LTDC_L1WHPCR, LXWHPCR_WHSTPOS | LXWHPCR_WHSPPOS,
			val);

	/* Vertical start & stop position */
	tmp = readl(regs + LTDC_BPCR) & BPCR_AVBP;
	val = ((y1 + 1 + tmp) << 16) + (y0 + 1 + tmp);
	clrsetbits_le32(regs + LTDC_L1WVPCR, LXWVPCR_WVSTPOS | LXWVPCR_WVSPPOS,
			val);

	/* Layer background color */
	writel(priv->bg_col_argb, regs + LTDC_L1DCCR);

	/* Color frame buffer pitch in bytes & line length */
	bpp = VNBITS(priv->l2bpp);
	pitch_in_bytes = priv->crop_w * (bpp >> 3);
	bus_width = 8 << ((readl(regs + LTDC_GC2R) & GC2R_BW) >> 4);
	line_length = ((bpp >> 3) * priv->crop_w) + (bus_width >> 3) - 1;
	val = (pitch_in_bytes << 16) | line_length;
	clrsetbits_le32(regs + LTDC_L1CFBLR, LXCFBLR_CFBLL | LXCFBLR_CFBP, val);

	/* Pixel format */
	format = stm32_ltdc_get_pixel_format(priv->l2bpp);
	for (val = 0; val < NB_PF; val++)
		if (priv->pix_fmt_hw[val] == format)
			break;

	if (val >= NB_PF) {
		log_err("invalid pixel format\n");
		return;
	}

	clrsetbits_le32(regs + LTDC_L1PFCR, LXPFCR_PF, val);

	/* Constant alpha value */
	clrsetbits_le32(regs + LTDC_L1CACR, LXCACR_CONSTA, priv->alpha);

	/* Specifies the blending factors : with or without pixel alpha */
	/* Manage hw-specific capabilities */
	val = has_alpha(format) ? BF1_PAXCA | BF2_1PAXCA : BF1_CA | BF2_1CA;

	/* Blending factors */
	clrsetbits_le32(regs + LTDC_L1BFCR, LXBFCR_BF2 | LXBFCR_BF1, val);

	/* Frame buffer line number */
	clrsetbits_le32(regs + LTDC_L1CFBLNR, LXCFBLNR_CFBLN, priv->crop_h);

	/* Frame buffer address */
	writel(fb_addr, regs + LTDC_L1CFBAR);

	/* Enable layer 1 */
	setbits_le32(priv->regs + LTDC_L1CR, LXCR_LEN);
}

#if IS_ENABLED(CONFIG_TARGET_STM32F469_DISCOVERY)
static int stm32_ltdc_alloc_fb(struct udevice *dev)
{
	u32 sdram_size = gd->ram_size;
	struct video_uc_plat *uc_plat = dev_get_uclass_plat(dev);
	phys_addr_t cpu;
	dma_addr_t bus;
	u64 dma_size;
	int ret;

	ret = dev_get_dma_range(dev, &cpu, &bus, &dma_size);
	if (ret) {
		dev_err(dev, "failed to get dma address\n");
		return ret;
	}

	uc_plat->base = bus + sdram_size - ALIGN(uc_plat->size, uc_plat->align);
	return 0;
}
#else
static inline int stm32_ltdc_alloc_fb(struct udevice *dev)
{
	/* Delegate framebuffer allocation to video-uclass */
	return 0;
}
#endif

static int stm32_ltdc_probe(struct udevice *dev)
{
	struct video_uc_plat *uc_plat = dev_get_uclass_plat(dev);
	struct video_priv *uc_priv = dev_get_uclass_priv(dev);
	struct stm32_ltdc_priv *priv = dev_get_priv(dev);
	struct udevice *bridge = NULL;
	struct udevice *panel = NULL;
	struct display_timing timings;
	struct clk pclk;
	struct reset_ctl rst;
	ulong rate;
	int ret;

	priv->regs = dev_read_addr_ptr(dev);
	if (!priv->regs) {
		dev_err(dev, "ltdc dt register address error\n");
		return -EINVAL;
	}

	ret = clk_get_by_index(dev, 0, &pclk);
	if (ret) {
		dev_err(dev, "peripheral clock get error %d\n", ret);
		return ret;
	}

	ret = clk_enable(&pclk);
	if (ret) {
		dev_err(dev, "peripheral clock enable error %d\n", ret);
		return ret;
	}

	priv->hw_version = readl(priv->regs + LTDC_IDR);
	debug("%s: LTDC hardware 0x%x\n", __func__, priv->hw_version);

	switch (priv->hw_version) {
	case HWVER_10200:
	case HWVER_10300:
		priv->layer_regs = layer_regs_a0;
		priv->pix_fmt_hw = pix_fmt_a0;
		break;
	case HWVER_20101:
		priv->layer_regs = layer_regs_a1;
		priv->pix_fmt_hw = pix_fmt_a1;
		break;
	case HWVER_40100:
		priv->layer_regs = layer_regs_a2;
		priv->pix_fmt_hw = pix_fmt_a2;
		break;
	default:
		return -ENODEV;
	}

	ret = uclass_first_device_err(UCLASS_PANEL, &panel);
	if (ret) {
		if (ret != -ENODEV)
			dev_err(dev, "panel device error %d\n", ret);
		return ret;
	}

	ret = panel_get_display_timing(panel, &timings);
	if (ret) {
		ret = ofnode_decode_display_timing(dev_ofnode(panel),
						   0, &timings);
		if (ret) {
			dev_err(dev, "decode display timing error %d\n", ret);
			return ret;
		}
	}

	rate = clk_set_rate(&pclk, timings.pixelclock.typ);
	if (IS_ERR_VALUE(rate))
		dev_warn(dev, "fail to set pixel clock %d hz, ret=%ld\n",
			 timings.pixelclock.typ, rate);

	dev_dbg(dev, "Set pixel clock req %d hz get %ld hz\n",
		timings.pixelclock.typ, rate);

	ret = reset_get_by_index(dev, 0, &rst);
	if (ret) {
		dev_err(dev, "missing ltdc hardware reset\n");
		return ret;
	}

	/* Reset */
	reset_deassert(&rst);

	if (IS_ENABLED(CONFIG_VIDEO_BRIDGE)) {
		ret = uclass_get_device(UCLASS_VIDEO_BRIDGE, 0, &bridge);
		if (ret)
			dev_dbg(dev,
				"No video bridge, or no backlight on bridge\n");

		if (bridge) {
			ret = video_bridge_attach(bridge);
			if (ret) {
				dev_err(bridge, "fail to attach bridge\n");
				return ret;
			}
		}
	}

	/* TODO Below parameters are hard-coded for the moment... */
	priv->l2bpp = VIDEO_BPP16;
	priv->bg_col_argb = 0xFFFFFFFF; /* white no transparency */
	priv->crop_x = 0;
	priv->crop_y = 0;
	priv->crop_w = timings.hactive.typ;
	priv->crop_h = timings.vactive.typ;
	priv->alpha = 0xFF;

	ret = stm32_ltdc_alloc_fb(dev);
	if (ret)
		return ret;

	dev_dbg(dev, "%dx%d %dbpp frame buffer at 0x%lx\n",
		timings.hactive.typ, timings.vactive.typ,
		VNBITS(priv->l2bpp), uc_plat->base);
	dev_dbg(dev, "crop %d,%d %dx%d bg 0x%08x alpha %d\n",
		priv->crop_x, priv->crop_y, priv->crop_w, priv->crop_h,
		priv->bg_col_argb, priv->alpha);

	/* Configure & start LTDC */
	stm32_ltdc_set_mode(priv, &timings);
	stm32_ltdc_set_layer1(priv, uc_plat->base);
	stm32_ltdc_enable(priv);

	uc_priv->xsize = timings.hactive.typ;
	uc_priv->ysize = timings.vactive.typ;
	uc_priv->bpix = priv->l2bpp;

	if (!bridge) {
		ret = panel_enable_backlight(panel);
		if (ret) {
			dev_err(dev, "panel %s enable backlight error %d\n",
				panel->name, ret);
			return ret;
		}
	} else if (IS_ENABLED(CONFIG_VIDEO_BRIDGE)) {
		ret = video_bridge_set_backlight(bridge, 80);
		if (ret) {
			dev_err(dev, "fail to set backlight\n");
			return ret;
		}
	}

	video_set_flush_dcache(dev, true);

	return 0;
}

static int stm32_ltdc_bind(struct udevice *dev)
{
	struct video_uc_plat *uc_plat = dev_get_uclass_plat(dev);

	uc_plat->size = CONFIG_VIDEO_STM32_MAX_XRES *
			CONFIG_VIDEO_STM32_MAX_YRES *
			(CONFIG_VIDEO_STM32_MAX_BPP >> 3);
	/* align framebuffer on kernel MMU_SECTION_SIZE = max 2MB for LPAE */
	uc_plat->align = SZ_2M;
	dev_dbg(dev, "frame buffer max size %d bytes align %x\n",
		uc_plat->size, uc_plat->align);

	return 0;
}

static const struct udevice_id stm32_ltdc_ids[] = {
	{ .compatible = "st,stm32-ltdc" },
	{ }
};

U_BOOT_DRIVER(stm32_ltdc) = {
	.name			= "stm32_display",
	.id			= UCLASS_VIDEO,
	.of_match		= stm32_ltdc_ids,
	.probe			= stm32_ltdc_probe,
	.bind			= stm32_ltdc_bind,
	.priv_auto	= sizeof(struct stm32_ltdc_priv),
};