Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Tue, 6 Sep 2022 23:52:24 +0200
From:   Daniel Vetter <daniel@ffwll.ch>
To:     Markuss Broks <markuss.broks@gmail.com>
Cc:     linux-kernel@vger.kernel.org,
        ~postmarketos/upstreaming@lists.sr.ht, phone-devel@vger.kernel.org,
        Jonathan Corbet <corbet@lwn.net>,
        Ard Biesheuvel <ardb@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jiri Slaby <jirislaby@kernel.org>,
        Helge Deller <deller@gmx.de>,
        "Paul E. McKenney" <paulmck@kernel.org>,
        Borislav Petkov <bp@suse.de>,
        Kees Cook <keescook@chromium.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Randy Dunlap <rdunlap@infradead.org>,
        Damien Le Moal <damien.lemoal@opensource.wdc.com>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        Michal Suchanek <msuchanek@suse.de>,
        Javier Martinez Canillas <javierm@redhat.com>,
        Arnd Bergmann <arnd@arndb.de>,
        Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Wei Ming Chen <jj251510319013@gmail.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
        Tony Lindgren <tony@atomide.com>, linux-doc@vger.kernel.org,
        linux-efi@vger.kernel.org, linux-serial@vger.kernel.org,
        linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org
Subject: Re: [PATCH v2 3/3] efi: earlycon: Add support for generic
 framebuffers and move to console subsystem
Message-ID: <YxfBGDg6YkIQ6Wzq@phenom.ffwll.local>
Mail-Followup-To: Markuss Broks <markuss.broks@gmail.com>,
        linux-kernel@vger.kernel.org, ~postmarketos/upstreaming@lists.sr.ht,
        phone-devel@vger.kernel.org, Jonathan Corbet <corbet@lwn.net>,
        Ard Biesheuvel <ardb@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jiri Slaby <jirislaby@kernel.org>, Helge Deller <deller@gmx.de>,
        "Paul E. McKenney" <paulmck@kernel.org>,
        Borislav Petkov <bp@suse.de>, Kees Cook <keescook@chromium.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Randy Dunlap <rdunlap@infradead.org>,
        Damien Le Moal <damien.lemoal@opensource.wdc.com>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        Michal Suchanek <msuchanek@suse.de>,
        Javier Martinez Canillas <javierm@redhat.com>,
        Arnd Bergmann <arnd@arndb.de>,
        Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Wei Ming Chen <jj251510319013@gmail.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
        Tony Lindgren <tony@atomide.com>, linux-doc@vger.kernel.org,
        linux-efi@vger.kernel.org, linux-serial@vger.kernel.org,
        linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org
References: <20220806163255.10404-1-markuss.broks@gmail.com>
 <20220806163255.10404-4-markuss.broks@gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20220806163255.10404-4-markuss.broks@gmail.com>
Precedence: bulk

On Sat, Aug 06, 2022 at 07:32:24PM +0300, Markuss Broks wrote:
> 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 and on IA64 because of lack of early_memremap_prot.
> 
> Signed-off-by: Markuss Broks <markuss.broks@gmail.com>
> ---
>  .../admin-guide/kernel-parameters.txt         |  12 +-
>  MAINTAINERS                                   |   5 +
>  drivers/firmware/efi/Kconfig                  |   7 +-
>  drivers/firmware/efi/Makefile                 |   1 -
>  drivers/firmware/efi/earlycon.c               | 246 --------------
>  drivers/video/console/Kconfig                 |  11 +
>  drivers/video/console/Makefile                |   1 +
>  drivers/video/console/earlycon.c              | 305 ++++++++++++++++++

Ok I have a more fundamental issue with this than the lack of proper patch
splitting I mentioned in the other thread.

This is the wrong place.

drivers/video/console is about the various vt console implementations,
which supply a struct consw to con_register_driver.

This otoh is an (early) kernel/printk console implemented using struct
console. Totally different thing, and really shouldn't end up in
drivers/video/console imo. Somewhere in drivers/firmware might still be
the best place, the sysfb stuff is also there. Maybe
drivers/firmware/sysfb_earlycon.c?

Also patch split is still an issue here, like I and Greg already said.
-Daniel

>  8 files changed, 332 insertions(+), 256 deletions(-)
>  delete mode 100644 drivers/firmware/efi/earlycon.c
>  create mode 100644 drivers/video/console/earlycon.c
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 8090130b544b0701237a7b657a29c83c000a60f4..bccb1ac8978eb5cf7e2bb20834b1881b27040666 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>x<height>x<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..af8b8e289483b6a264d477145061bd0e0ba34a25 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@gmail.com>
> +S:	Maintained
> +F:	drivers/video/console/earlycon.c
> +
>  EARTH_PT1 MEDIA DRIVER
>  M:	Akihiro Tsukada <tskd08@gmail.com>
>  L:	linux-media@vger.kernel.org
> diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig
> index 7aa4717cdcac46f91dd202f868c463388eb02735..ea76ccfb9bcd8ba44ddca06052eaa442ed6c30f7 100644
> --- a/drivers/firmware/efi/Kconfig
> +++ b/drivers/firmware/efi/Kconfig
> @@ -259,10 +259,9 @@ 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"
> +	select FB_EARLYCON
> +	default y
>  
>  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/console/Kconfig b/drivers/video/console/Kconfig
> index 40c50fa2dd70c33a1549141b15e6cba721352d2d..8052507e058fce37f5a51058e58ae2eb10d9669a 100644
> --- a/drivers/video/console/Kconfig
> +++ b/drivers/video/console/Kconfig
> @@ -69,6 +69,17 @@ config DUMMY_CONSOLE_ROWS
>  	  monitor.
>  	  Select 25 if you use a 640x480 resolution by default.
>  
> +config FB_EARLYCON
> +	bool "Generic framebuffer early console"
> +	depends on SERIAL_EARLYCON && !ARM && !IA64
> +	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 FRAMEBUFFER_CONSOLE
>  	bool "Framebuffer Console support"
>  	depends on FB && !UML
> diff --git a/drivers/video/console/Makefile b/drivers/video/console/Makefile
> index db07b784bd2ccdcbffde933926ed5cee2bbbc7d4..7818faee587fc9c40b429617cfa224c0ccbc557c 100644
> --- a/drivers/video/console/Makefile
> +++ b/drivers/video/console/Makefile
> @@ -9,4 +9,5 @@ obj-$(CONFIG_STI_CONSOLE)         += sticon.o sticore.o
>  obj-$(CONFIG_VGA_CONSOLE)         += vgacon.o
>  obj-$(CONFIG_MDA_CONSOLE)         += mdacon.o
>  
> +obj-$(CONFIG_FB_EARLYCON)         += earlycon.o
>  obj-$(CONFIG_FB_STI)              += sticore.o
> diff --git a/drivers/video/console/earlycon.c b/drivers/video/console/earlycon.c
> new file mode 100644
> index 0000000000000000000000000000000000000000..54436587e3db90034652dcc144669dca91b863d5
> --- /dev/null
> +++ b/drivers/video/console/earlycon.c
> @@ -0,0 +1,305 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2013 Intel Corporation; author Matt Fleming
> + * Copyright (C) 2022 Markuss Broks <markuss.broks@gmail.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)
> +{
> +	unsigned long mapping;
> +	/* bail if there is no bootconsole or it has been disabled already */
> +	if (!earlycon_console || !(earlycon_console->flags & CON_ENABLED))
> +		return 0;
> +
> +	if (region_intersects(info.phys_base, info.size,
> +			      IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE) == REGION_INTERSECTS)		
> +		mapping = MEMREMAP_WB;
> +	else
> +		mapping = MEMREMAP_WC;
> +
> +	info.virt_base = memremap(info.phys_base, info.size, mapping);
> +
> +	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.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, "%ux%ux%u", &info.x, &info.y, &info.depth);
> +	if (ret != 3)
> +		return -ENODEV;
> +
> +	info.stride = info.x * (info.depth / 8);
> +
> +	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;
> +	info.stride = screen_info.lfb_linelength;
> +
> +	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->offset, "width", NULL);
> +	if (!val)
> +		return -ENODEV;
> +	info.x = be32_to_cpu(*val);
> +
> +	val = of_get_flat_dt_prop(device->offset, "height", NULL);
> +	if (!val)
> +		return -ENODEV;
> +	info.y = be32_to_cpu(*val);
> +
> +	val = of_get_flat_dt_prop(device->offset, "stride", NULL);
> +	if (!val)
> +		return -ENODEV;
> +	info.stride = be32_to_cpu(*val);
> +	info.depth = (info.stride / info.x) * 8;
> +
> +	return simplefb_earlycon_setup_common(device, opt);
> +}
> +
> +OF_EARLYCON_DECLARE(simplefb, "simple-framebuffer", simplefb_earlycon_setup_of);
> +#endif
> -- 
> 2.37.0
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch