Message-Id: <20220728142824.3836-3-markuss.broks@gmail.com>
Date:   Thu, 28 Jul 2022 17:28:19 +0300
From:   Markuss Broks <markuss.broks@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     ~postmarketos/upstreaming@...ts.sr.ht, phone-devel@...r.kernel.org,
        Markuss Broks <markuss.broks@...il.com>,
        Jonathan Corbet <corbet@....net>,
        Ard Biesheuvel <ardb@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Helge Deller <deller@....de>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Borislav Petkov <bp@...e.de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Kees Cook <keescook@...omium.org>,
        Randy Dunlap <rdunlap@...radead.org>,
        Damien Le Moal <damien.lemoal@...nsource.wdc.com>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Javier Martinez Canillas <javierm@...hat.com>,
        Michal Suchanek <msuchanek@...e.de>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Arnd Bergmann <arnd@...db.de>,
        Wei Ming Chen <jj251510319013@...il.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Tony Lindgren <tony@...mide.com>, linux-doc@...r.kernel.org,
        linux-efi@...r.kernel.org, linux-serial@...r.kernel.org,
        linux-fbdev@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        Rob Herring <robh@...nel.org>
Subject: [PATCH 2/2] efi: earlycon: Add support for generic framebuffers and move to fbdev subsystem

Add early console support for generic linear framebuffer devices.
This driver supports probing from cmdline early parameters
or from the device-tree using information in simple-framebuffer node.
The EFI functionality should be retained in whole.
The driver was disabled on ARM because of a bug in early_ioremap
implementation on ARM.

Signed-off-by: Markuss Broks <markuss.broks@...il.com>
---
 .../admin-guide/kernel-parameters.txt         |  12 +-
 MAINTAINERS                                   |   5 +
 drivers/firmware/efi/Kconfig                  |   6 +-
 drivers/firmware/efi/Makefile                 |   1 -
 drivers/firmware/efi/earlycon.c               | 246 --------------
 drivers/video/fbdev/Kconfig                   |  11 +
 drivers/video/fbdev/Makefile                  |   1 +
 drivers/video/fbdev/earlycon.c                | 301 ++++++++++++++++++
 8 files changed, 327 insertions(+), 256 deletions(-)
 delete mode 100644 drivers/firmware/efi/earlycon.c
 create mode 100644 drivers/video/fbdev/earlycon.c

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 8090130b544b0701237a7b657a29c83c000a60f4..22a8625bb342f95e731fcc3a24390fca2c0f194c 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1281,12 +1281,9 @@
 			specified address. The serial port must already be
 			setup and configured. Options are not yet supported.
 
-		efifb,[options]
+		efifb
 			Start an early, unaccelerated console on the EFI
-			memory mapped framebuffer (if available). On cache
-			coherent non-x86 systems that use system memory for
-			the framebuffer, pass the 'ram' option so that it is
-			mapped with the correct attributes.
+			memory mapped framebuffer (if available).
 
 		linflex,<addr>
 			Use early console provided by Freescale LINFlexD UART
@@ -1294,6 +1291,11 @@
 			address must be provided, and the serial port must
 			already be setup and configured.
 
+		simplefb,<addr>,<width>,<height>,<bpp>
+			Use early console with simple framebuffer that is
+			pre-initialized by firmware. A valid base address,
+			width, height and pixel size must be provided.
+
 	earlyprintk=	[X86,SH,ARM,M68k,S390]
 			earlyprintk=vga
 			earlyprintk=sclp
diff --git a/MAINTAINERS b/MAINTAINERS
index 1fc9ead83d2aa3e60ccc4cfa8ee16df09ef579bf..140dee7f6920197a895d310afdde67a0de474522 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -7033,6 +7033,11 @@ Q:	http://patchwork.linuxtv.org/project/linux-media/list/
 T:	git git://linuxtv.org/anttip/media_tree.git
 F:	drivers/media/tuners/e4000*
 
+EARLY CONSOLE FRAMEBUFFER DRIVER
+M:	Markuss Broks <markuss.broks@...il.com>
+S:	Maintained
+F:	drivers/video/fbdev/earlycon.c
+
 EARTH_PT1 MEDIA DRIVER
 M:	Akihiro Tsukada <tskd08@...il.com>
 L:	linux-media@...r.kernel.org
diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig
index 7aa4717cdcac46f91dd202f868c463388eb02735..56241b2e19383d70387f07114a27bb4f33ac7857 100644
--- a/drivers/firmware/efi/Kconfig
+++ b/drivers/firmware/efi/Kconfig
@@ -259,10 +259,8 @@ config EFI_DISABLE_PCI_DMA
 	  may be used to override this option.
 
 config EFI_EARLYCON
-	def_bool y
-	depends on SERIAL_EARLYCON && !ARM && !IA64
-	select FONT_SUPPORT
-	select ARCH_USE_MEMREMAP_PROT
+	bool "EFI early console support"
+	depends on FB_EARLYCON && !IA64
 
 config EFI_CUSTOM_SSDT_OVERLAYS
 	bool "Load custom ACPI SSDT overlay from an EFI variable"
diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
index c02ff25dd47707090a2ab86ee4f330e467f878f5..64eea61fbb43d76ec2d5416d467dfbb9aa21bda0 100644
--- a/drivers/firmware/efi/Makefile
+++ b/drivers/firmware/efi/Makefile
@@ -44,6 +44,5 @@ obj-$(CONFIG_ARM64)			+= $(arm-obj-y)
 riscv-obj-$(CONFIG_EFI)			:= efi-init.o riscv-runtime.o
 obj-$(CONFIG_RISCV)			+= $(riscv-obj-y)
 obj-$(CONFIG_EFI_CAPSULE_LOADER)	+= capsule-loader.o
-obj-$(CONFIG_EFI_EARLYCON)		+= earlycon.o
 obj-$(CONFIG_UEFI_CPER_ARM)		+= cper-arm.o
 obj-$(CONFIG_UEFI_CPER_X86)		+= cper-x86.o
diff --git a/drivers/firmware/efi/earlycon.c b/drivers/firmware/efi/earlycon.c
deleted file mode 100644
index a52236e11e5f73ddea5bb1f42ca2ca7c42425dab..0000000000000000000000000000000000000000
--- a/drivers/firmware/efi/earlycon.c
+++ /dev/null
@@ -1,246 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * Copyright (C) 2013 Intel Corporation; author Matt Fleming
- */
-
-#include <linux/console.h>
-#include <linux/efi.h>
-#include <linux/font.h>
-#include <linux/io.h>
-#include <linux/kernel.h>
-#include <linux/serial_core.h>
-#include <linux/screen_info.h>
-
-#include <asm/early_ioremap.h>
-
-static const struct console *earlycon_console __initdata;
-static const struct font_desc *font;
-static u32 efi_x, efi_y;
-static u64 fb_base;
-static bool fb_wb;
-static void *efi_fb;
-
-/*
- * EFI earlycon needs to use early_memremap() to map the framebuffer.
- * But early_memremap() is not usable for 'earlycon=efifb keep_bootcon',
- * memremap() should be used instead. memremap() will be available after
- * paging_init() which is earlier than initcall callbacks. Thus adding this
- * early initcall function early_efi_map_fb() to map the whole EFI framebuffer.
- */
-static int __init efi_earlycon_remap_fb(void)
-{
-	/* bail if there is no bootconsole or it has been disabled already */
-	if (!earlycon_console || !(earlycon_console->flags & CON_ENABLED))
-		return 0;
-
-	efi_fb = memremap(fb_base, screen_info.lfb_size,
-			  fb_wb ? MEMREMAP_WB : MEMREMAP_WC);
-
-	return efi_fb ? 0 : -ENOMEM;
-}
-early_initcall(efi_earlycon_remap_fb);
-
-static int __init efi_earlycon_unmap_fb(void)
-{
-	/* unmap the bootconsole fb unless keep_bootcon has left it enabled */
-	if (efi_fb && !(earlycon_console->flags & CON_ENABLED))
-		memunmap(efi_fb);
-	return 0;
-}
-late_initcall(efi_earlycon_unmap_fb);
-
-static __ref void *efi_earlycon_map(unsigned long start, unsigned long len)
-{
-	pgprot_t fb_prot;
-
-	if (efi_fb)
-		return efi_fb + start;
-
-	fb_prot = fb_wb ? PAGE_KERNEL : pgprot_writecombine(PAGE_KERNEL);
-	return early_memremap_prot(fb_base + start, len, pgprot_val(fb_prot));
-}
-
-static __ref void efi_earlycon_unmap(void *addr, unsigned long len)
-{
-	if (efi_fb)
-		return;
-
-	early_memunmap(addr, len);
-}
-
-static void efi_earlycon_clear_scanline(unsigned int y)
-{
-	unsigned long *dst;
-	u16 len;
-
-	len = screen_info.lfb_linelength;
-	dst = efi_earlycon_map(y*len, len);
-	if (!dst)
-		return;
-
-	memset(dst, 0, len);
-	efi_earlycon_unmap(dst, len);
-}
-
-static void efi_earlycon_scroll_up(void)
-{
-	unsigned long *dst, *src;
-	u16 len;
-	u32 i, height;
-
-	len = screen_info.lfb_linelength;
-	height = screen_info.lfb_height;
-
-	for (i = 0; i < height - font->height; i++) {
-		dst = efi_earlycon_map(i*len, len);
-		if (!dst)
-			return;
-
-		src = efi_earlycon_map((i + font->height) * len, len);
-		if (!src) {
-			efi_earlycon_unmap(dst, len);
-			return;
-		}
-
-		memmove(dst, src, len);
-
-		efi_earlycon_unmap(src, len);
-		efi_earlycon_unmap(dst, len);
-	}
-}
-
-static void efi_earlycon_write_char(u32 *dst, unsigned char c, unsigned int h)
-{
-	const u32 color_black = 0x00000000;
-	const u32 color_white = 0x00ffffff;
-	const u8 *src;
-	int m, n, bytes;
-	u8 x;
-
-	bytes = BITS_TO_BYTES(font->width);
-	src = font->data + c * font->height * bytes + h * bytes;
-
-	for (m = 0; m < font->width; m++) {
-		n = m % 8;
-		x = *(src + m / 8);
-		if ((x >> (7 - n)) & 1)
-			*dst = color_white;
-		else
-			*dst = color_black;
-		dst++;
-	}
-}
-
-static void
-efi_earlycon_write(struct console *con, const char *str, unsigned int num)
-{
-	struct screen_info *si;
-	unsigned int len;
-	const char *s;
-	void *dst;
-
-	si = &screen_info;
-	len = si->lfb_linelength;
-
-	while (num) {
-		unsigned int linemax;
-		unsigned int h, count = 0;
-
-		for (s = str; *s && *s != '\n'; s++) {
-			if (count == num)
-				break;
-			count++;
-		}
-
-		linemax = (si->lfb_width - efi_x) / font->width;
-		if (count > linemax)
-			count = linemax;
-
-		for (h = 0; h < font->height; h++) {
-			unsigned int n, x;
-
-			dst = efi_earlycon_map((efi_y + h) * len, len);
-			if (!dst)
-				return;
-
-			s = str;
-			n = count;
-			x = efi_x;
-
-			while (n-- > 0) {
-				efi_earlycon_write_char(dst + x*4, *s, h);
-				x += font->width;
-				s++;
-			}
-
-			efi_earlycon_unmap(dst, len);
-		}
-
-		num -= count;
-		efi_x += count * font->width;
-		str += count;
-
-		if (num > 0 && *s == '\n') {
-			efi_x = 0;
-			efi_y += font->height;
-			str++;
-			num--;
-		}
-
-		if (efi_x + font->width > si->lfb_width) {
-			efi_x = 0;
-			efi_y += font->height;
-		}
-
-		if (efi_y + font->height > si->lfb_height) {
-			u32 i;
-
-			efi_y -= font->height;
-			efi_earlycon_scroll_up();
-
-			for (i = 0; i < font->height; i++)
-				efi_earlycon_clear_scanline(efi_y + i);
-		}
-	}
-}
-
-static int __init efi_earlycon_setup(struct earlycon_device *device,
-				     const char *opt)
-{
-	struct screen_info *si;
-	u16 xres, yres;
-	u32 i;
-
-	if (screen_info.orig_video_isVGA != VIDEO_TYPE_EFI)
-		return -ENODEV;
-
-	fb_base = screen_info.lfb_base;
-	if (screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE)
-		fb_base |= (u64)screen_info.ext_lfb_base << 32;
-
-	fb_wb = opt && !strcmp(opt, "ram");
-
-	si = &screen_info;
-	xres = si->lfb_width;
-	yres = si->lfb_height;
-
-	/*
-	 * efi_earlycon_write_char() implicitly assumes a framebuffer with
-	 * 32 bits per pixel.
-	 */
-	if (si->lfb_depth != 32)
-		return -ENODEV;
-
-	font = get_default_font(xres, yres, -1, -1);
-	if (!font)
-		return -ENODEV;
-
-	efi_y = rounddown(yres, font->height) - font->height;
-	for (i = 0; i < (yres - efi_y) / font->height; i++)
-		efi_earlycon_scroll_up();
-
-	device->con->write = efi_earlycon_write;
-	earlycon_console = device->con;
-	return 0;
-}
-EARLYCON_DECLARE(efifb, efi_earlycon_setup);
diff --git a/drivers/video/fbdev/Kconfig b/drivers/video/fbdev/Kconfig
index f2a6b81e45c41334db71cca35f4fa5a827f728fe..2bb3f7a9e6e0f8ad2e9042d8c602b1cdec30755c 100644
--- a/drivers/video/fbdev/Kconfig
+++ b/drivers/video/fbdev/Kconfig
@@ -627,6 +627,17 @@ config FB_VESA
 	  You will get a boot time penguin logo at no additional cost. Please
 	  read <file:Documentation/fb/vesafb.rst>. If unsure, say Y.
 
+config FB_EARLYCON
+	bool "Generic framebuffer early console"
+	depends on FB && SERIAL_EARLYCON && !ARM
+	select FONT_SUPPORT
+	select ARCH_USE_MEMREMAP_PROT
+	help
+	  Say Y here if you want early console support for firmware established
+	  linear framebuffer. Unless you are using EFI framebuffer, you need to
+	  specify framebuffer geometry and address in device-tree or in kernel
+	  command line.
+
 config FB_EFI
 	bool "EFI-based Framebuffer Support"
 	depends on (FB = y) && !IA64 && EFI
diff --git a/drivers/video/fbdev/Makefile b/drivers/video/fbdev/Makefile
index 7795c4126706fd7bb832d94da5d14b0060849d1f..07406ab45a3f306a07d008a9f0a401347aeaa695 100644
--- a/drivers/video/fbdev/Makefile
+++ b/drivers/video/fbdev/Makefile
@@ -129,6 +129,7 @@ obj-$(CONFIG_FB_MX3)		  += mx3fb.o
 obj-$(CONFIG_FB_DA8XX)		  += da8xx-fb.o
 obj-$(CONFIG_FB_SSD1307)	  += ssd1307fb.o
 obj-$(CONFIG_FB_SIMPLE)           += simplefb.o
+obj-$(CONFIG_FB_EARLYCON)         += earlycon.o
 
 # the test framebuffer is last
 obj-$(CONFIG_FB_VIRTUAL)          += vfb.o
diff --git a/drivers/video/fbdev/earlycon.c b/drivers/video/fbdev/earlycon.c
new file mode 100644
index 0000000000000000000000000000000000000000..5f6f4b228a50f23c1c77cf7ba5d50ff833efdd46
--- /dev/null
+++ b/drivers/video/fbdev/earlycon.c
@@ -0,0 +1,301 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2013 Intel Corporation; author Matt Fleming
+ * Copyright (C) 2022 Markuss Broks <markuss.broks@...il.com>
+ */
+
+#include <asm/early_ioremap.h>
+#include <linux/console.h>
+#include <linux/efi.h>
+#include <linux/font.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/of.h>
+#include <linux/of_fdt.h>
+#include <linux/serial_core.h>
+#include <linux/screen_info.h>
+
+struct fb_earlycon {
+	u32 x, y, curr_x, curr_y, depth, stride;
+	size_t size;
+	phys_addr_t phys_base;
+	void __iomem *virt_base;
+};
+
+static const struct console *earlycon_console __initconst;
+static struct fb_earlycon info;
+static const struct font_desc *font;
+
+static int __init simplefb_earlycon_remap_fb(void)
+{
+	int is_ram;
+	/* bail if there is no bootconsole or it has been disabled already */
+	if (!earlycon_console || !(earlycon_console->flags & CON_ENABLED))
+		return 0;
+
+	is_ram = region_intersects(info.phys_base, info.size,
+				   IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE);
+	is_ram = is_ram == REGION_INTERSECTS;
+
+	info.virt_base = memremap(info.phys_base, info.size,
+				  is_ram ? MEMREMAP_WB : MEMREMAP_WC);
+
+	return info.virt_base ? 0 : -ENOMEM;
+}
+early_initcall(simplefb_earlycon_remap_fb);
+
+static int __init simplefb_earlycon_unmap_fb(void)
+{
+	/* unmap the bootconsole fb unless keep_bootcon has left it enabled */
+	if (info.virt_base && !(earlycon_console->flags & CON_ENABLED))
+		memunmap(info.virt_base);
+	return 0;
+}
+late_initcall(simplefb_earlycon_unmap_fb);
+
+static __ref void *simplefb_earlycon_map(unsigned long start, unsigned long len)
+{
+	pgprot_t fb_prot;
+
+	if (info.virt_base)
+		return info.virt_base + start;
+
+	fb_prot = PAGE_KERNEL;
+	return early_memremap_prot(info.phys_base + start, len, pgprot_val(fb_prot));
+}
+
+static __ref void simplefb_earlycon_unmap(void *addr, unsigned long len)
+{
+	if (info.virt_base)
+		return;
+
+	early_memunmap(addr, len);
+}
+
+static void simplefb_earlycon_clear_scanline(unsigned int y)
+{
+	unsigned long *dst;
+	u16 len;
+
+	len = info.stride;
+	dst = simplefb_earlycon_map(y * len, len);
+	if (!dst)
+		return;
+
+	memset(dst, 0, len);
+	simplefb_earlycon_unmap(dst, len);
+}
+
+static void simplefb_earlycon_scroll_up(void)
+{
+	unsigned long *dst, *src;
+	u16 len;
+	u32 i, height;
+
+	len = info.stride;
+	height = info.y;
+
+	for (i = 0; i < height - font->height; i++) {
+		dst = simplefb_earlycon_map(i * len, len);
+		if (!dst)
+			return;
+
+		src = simplefb_earlycon_map((i + font->height) * len, len);
+		if (!src) {
+			simplefb_earlycon_unmap(dst, len);
+			return;
+		}
+
+		memmove(dst, src, len);
+
+		simplefb_earlycon_unmap(src, len);
+		simplefb_earlycon_unmap(dst, len);
+	}
+}
+
+static void simplefb_earlycon_write_char(u8 *dst, unsigned char c, unsigned int h)
+{
+	const u8 *src;
+	int m, n, bytes;
+	u8 x;
+
+	bytes = BITS_TO_BYTES(font->width);
+	src = font->data + c * font->height * bytes + h * bytes;
+
+	for (m = 0; m < font->width; m++) {
+		n = m % 8;
+		x = *(src + m / 8);
+		if ((x >> (7 - n)) & 1)
+			memset(dst, 0xff, (info.depth / 8));
+		else
+			memset(dst, 0, (info.depth / 8));
+		dst += (info.depth / 8);
+	}
+}
+
+static void
+simplefb_earlycon_write(struct console *con, const char *str, unsigned int num)
+{
+	unsigned int len;
+	const char *s;
+	void *dst;
+
+	len = info.stride;
+
+	while (num) {
+		unsigned int linemax;
+		unsigned int h, count = 0;
+
+		for (s = str; *s && *s != '\n'; s++) {
+			if (count == num)
+				break;
+			count++;
+		}
+
+		linemax = (info.x - info.curr_x) / font->width;
+		if (count > linemax)
+			count = linemax;
+
+		for (h = 0; h < font->height; h++) {
+			unsigned int n, x;
+
+			dst = simplefb_earlycon_map((info.curr_y + h) * len, len);
+			if (!dst)
+				return;
+
+			s = str;
+			n = count;
+			x = info.curr_x;
+
+			while (n-- > 0) {
+				simplefb_earlycon_write_char(dst + (x * 4), *s, h);
+				x += font->width;
+				s++;
+			}
+
+			simplefb_earlycon_unmap(dst, len);
+		}
+
+		num -= count;
+		info.curr_x += count * font->width;
+		str += count;
+
+		if (num > 0 && *s == '\n') {
+			info.curr_x = 0;
+			info.curr_y += font->height;
+			str++;
+			num--;
+		}
+
+		if (info.curr_x + font->width > info.x) {
+			info.curr_x = 0;
+			info.curr_y += font->height;
+		}
+
+		if (info.curr_y + font->height > info.y) {
+			u32 i;
+
+			info.curr_y -= font->height;
+			simplefb_earlycon_scroll_up();
+
+			for (i = 0; i < font->height; i++)
+				simplefb_earlycon_clear_scanline(info.curr_y + i);
+		}
+	}
+}
+
+static int __init simplefb_earlycon_setup_common(struct earlycon_device *device,
+						 const char *opt)
+{
+	int i;
+
+	info.stride = info.x * 4;
+	info.size = info.x * info.y * (info.depth / 8);
+
+	font = get_default_font(info.x, info.y, -1, -1);
+	if (!font)
+		return -ENODEV;
+
+	info.curr_y = rounddown(info.y, font->height) - font->height;
+	for (i = 0; i < (info.y - info.curr_y) / font->height; i++)
+		simplefb_earlycon_scroll_up();
+
+	device->con->write = simplefb_earlycon_write;
+	earlycon_console = device->con;
+	return 0;
+}
+
+static int __init simplefb_earlycon_setup(struct earlycon_device *device,
+					  const char *opt)
+{
+	struct uart_port *port = &device->port;
+	int ret;
+
+	if (!port->mapbase)
+		return -ENODEV;
+
+	info.phys_base = port->mapbase;
+
+	ret = sscanf(device->options, "%u,%u,%u", &info.x, &info.y, &info.depth);
+	if (ret != 3)
+		return -ENODEV;
+
+	return simplefb_earlycon_setup_common(device, opt);
+}
+
+EARLYCON_DECLARE(simplefb, simplefb_earlycon_setup);
+
+#ifdef CONFIG_EFI_EARLYCON
+static int __init simplefb_earlycon_setup_efi(struct earlycon_device *device,
+					      const char *opt)
+{
+	if (screen_info.orig_video_isVGA != VIDEO_TYPE_EFI)
+		return -ENODEV;
+
+	info.phys_base = screen_info.lfb_base;
+	if (screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE)
+		info.phys_base |= (u64)screen_info.ext_lfb_base << 32;
+
+	info.x = screen_info.lfb_width;
+	info.y = screen_info.lfb_height;
+	info.depth = screen_info.lfb_depth;
+
+	return simplefb_earlycon_setup_common(device, opt);
+}
+
+EARLYCON_DECLARE(efifb, simplefb_earlycon_setup_efi);
+#endif
+
+#ifdef CONFIG_OF_EARLY_FLATTREE
+static int __init simplefb_earlycon_setup_of(struct earlycon_device *device,
+					     const char *opt)
+{
+	struct uart_port *port = &device->port;
+	const __be32 *val;
+
+	if (!port->mapbase)
+		return -ENODEV;
+
+	info.phys_base = port->mapbase;
+
+	val = of_get_flat_dt_prop(device->node, "width", NULL);
+	if (!val)
+		return -ENODEV;
+	info.x = be32_to_cpu(*val);
+
+	val = of_get_flat_dt_prop(device->node, "height", NULL);
+	if (!val)
+		return -ENODEV;
+	info.y = be32_to_cpu(*val);
+
+	val = of_get_flat_dt_prop(device->node, "stride", NULL);
+	if (!val)
+		return -ENODEV;
+	info.depth = (be32_to_cpu(*val) / info.x) * 8;
+
+	return simplefb_earlycon_setup_common(device, opt);
+}
+
+OF_EARLYCON_DECLARE(simplefb, "simple-framebuffer", simplefb_earlycon_setup_of);
+#endif
-- 
2.37.0

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