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Commit e3263ab3 authored by David Herrmann's avatar David Herrmann Committed by H. Peter Anvin
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x86: provide platform-devices for boot-framebuffers 



The current situation regarding boot-framebuffers (VGA, VESA/VBE, EFI) on
x86 causes troubles when loading multiple fbdev drivers. The global
"struct screen_info" does not provide any state-tracking about which
drivers use the FBs. request_mem_region() theoretically works, but
unfortunately vesafb/efifb ignore it due to quirks for broken boards.

Avoid this by creating a platform framebuffer devices with a pointer
to the "struct screen_info" as platform-data. Drivers can now create
platform-drivers and the driver-core will refuse multiple drivers being
active simultaneously.

We keep the screen_info available for backwards-compatibility. Drivers
can be converted in follow-up patches.

Different devices are created for VGA/VESA/EFI FBs to allow multiple
drivers to be loaded on distro kernels. We create:
 - "vesa-framebuffer" for VBE/VESA graphics FBs
 - "efi-framebuffer" for EFI FBs
 - "platform-framebuffer" for everything else
This allows to load vesafb, efifb and others simultaneously and each
picks up only the supported FB types.

Apart from platform-framebuffer devices, this also introduces a
compatibility option for "simple-framebuffer" drivers which recently got
introduced for OF based systems. If CONFIG_X86_SYSFB is selected, we
try to match the screen_info against a simple-framebuffer supported
format. If we succeed, we create a "simple-framebuffer" device instead
of a platform-framebuffer.
This allows to reuse the simplefb.c driver across architectures and also
to introduce a SimpleDRM driver. There is no need to have vesafb.c,
efifb.c, simplefb.c and more just to have architecture specific quirks
in their setup-routines.

Instead, we now move the architecture specific quirks into x86-setup and
provide a generic simple-framebuffer. For backwards-compatibility (if
strange formats are used), we still allow vesafb/efifb to be loaded
simultaneously and pick up all remaining devices.

Signed-off-by: default avatarDavid Herrmann <dh.herrmann@gmail.com>
Link: http://lkml.kernel.org/r/1375445127-15480-4-git-send-email-dh.herrmann@gmail.com


Tested-by: default avatarStephen Warren <swarren@nvidia.com>
Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
parent df0960ab

arch/x86/Kconfig

+26 −0
Original line number Diff line number Diff line
@@ -2270,6 +2270,32 @@ config RAPIDIO 


source "drivers/rapidio/Kconfig"



config X86_SYSFB

	bool "Mark VGA/VBE/EFI FB as generic system framebuffer"

	help

	  Firmwares often provide initial graphics framebuffers so the BIOS,

	  bootloader or kernel can show basic video-output during boot for

	  user-guidance and debugging. Historically, x86 used the VESA BIOS

	  Extensions and EFI-framebuffers for this, which are mostly limited

	  to x86.

	  This option, if enabled, marks VGA/VBE/EFI framebuffers as generic

	  framebuffers so the new generic system-framebuffer drivers can be

	  used on x86. If the framebuffer is not compatible with the generic

	  modes, it is adverticed as fallback platform framebuffer so legacy

	  drivers like efifb, vesafb and uvesafb can pick it up.

	  If this option is not selected, all system framebuffers are always

	  marked as fallback platform framebuffers as usual.



	  Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will

	  not be able to pick up generic system framebuffers if this option

	  is selected. You are highly encouraged to enable simplefb as

	  replacement if you select this option. simplefb can correctly deal

	  with generic system framebuffers. But you should still keep vesafb

	  and others enabled as fallback if a system framebuffer is

	  incompatible with simplefb.



	  If unsure, say Y.



endmenu

arch/x86/include/asm/sysfb.h

0 → 100644
+41 −0
Original line number Diff line number Diff line 
#ifndef _ARCH_X86_KERNEL_SYSFB_H

#define _ARCH_X86_KERNEL_SYSFB_H



/*

 * Generic System Framebuffers on x86

 * Copyright (c) 2012-2013 David Herrmann <dh.herrmann@gmail.com>

 *

 * This program is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License as published by the Free

 * Software Foundation; either version 2 of the License, or (at your option)

 * any later version.

 */



#include <linux/kernel.h>

#include <linux/platform_data/simplefb.h>

#include <linux/screen_info.h>



#ifdef CONFIG_X86_SYSFB



bool parse_mode(const struct screen_info *si,

		struct simplefb_platform_data *mode);

int create_simplefb(const struct screen_info *si,

		    const struct simplefb_platform_data *mode);



#else /* CONFIG_X86_SYSFB */



static inline bool parse_mode(const struct screen_info *si,

			      struct simplefb_platform_data *mode)

{

	return false;

}



static inline int create_simplefb(const struct screen_info *si,

				  const struct simplefb_platform_data *mode)

{

	return -EINVAL;

}



#endif /* CONFIG_X86_SYSFB */



#endif /* _ARCH_X86_KERNEL_SYSFB_H */

arch/x86/kernel/Makefile

+2 −0
Original line number Diff line number Diff line
@@ -103,6 +103,8 @@ obj-$(CONFIG_X86_CHECK_BIOS_CORRUPTION) += check.o 
obj-$(CONFIG_SWIOTLB)			+= pci-swiotlb.o

obj-$(CONFIG_OF)			+= devicetree.o

obj-$(CONFIG_UPROBES)			+= uprobes.o

obj-y					+= sysfb.o

obj-$(CONFIG_X86_SYSFB)			+= sysfb_simplefb.o



obj-$(CONFIG_PERF_EVENTS)		+= perf_regs.o

obj-$(CONFIG_TRACING)			+= tracepoint.o

arch/x86/kernel/sysfb.c

0 → 100644
+71 −0
Original line number Diff line number Diff line 
/*

 * Generic System Framebuffers on x86

 * Copyright (c) 2012-2013 David Herrmann <dh.herrmann@gmail.com>

 *

 * This program is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License as published by the Free

 * Software Foundation; either version 2 of the License, or (at your option)

 * any later version.

 */



/*

 * Simple-Framebuffer support for x86 systems

 * Create a platform-device for any available boot framebuffer. The

 * simple-framebuffer platform device is already available on DT systems, so

 * this module parses the global "screen_info" object and creates a suitable

 * platform device compatible with the "simple-framebuffer" DT object. If

 * the framebuffer is incompatible, we instead create a legacy

 * "vesa-framebuffer", "efi-framebuffer" or "platform-framebuffer" device and

 * pass the screen_info as platform_data. This allows legacy drivers

 * to pick these devices up without messing with simple-framebuffer drivers.

 * The global "screen_info" is still valid at all times.

 *

 * If CONFIG_X86_SYSFB is not selected, we never register "simple-framebuffer"

 * platform devices, but only use legacy framebuffer devices for

 * backwards compatibility.

 *

 * TODO: We set the dev_id field of all platform-devices to 0. This allows

 * other x86 OF/DT parsers to create such devices, too. However, they must

 * start at offset 1 for this to work.

 */



#include <linux/err.h>

#include <linux/init.h>

#include <linux/kernel.h>

#include <linux/mm.h>

#include <linux/platform_data/simplefb.h>

#include <linux/platform_device.h>

#include <linux/screen_info.h>

#include <asm/sysfb.h>



static __init int sysfb_init(void)

{

	struct screen_info *si = &screen_info;

	struct simplefb_platform_data mode;

	struct platform_device *pd;

	const char *name;

	bool compatible;

	int ret;



	/* try to create a simple-framebuffer device */

	compatible = parse_mode(si, &mode);

	if (compatible) {

		ret = create_simplefb(si, &mode);

		if (!ret)

			return 0;

	}



	/* if the FB is incompatible, create a legacy framebuffer device */

	if (si->orig_video_isVGA == VIDEO_TYPE_EFI)

		name = "efi-framebuffer";

	else if (si->orig_video_isVGA == VIDEO_TYPE_VLFB)

		name = "vesa-framebuffer";

	else

		name = "platform-framebuffer";



	pd = platform_device_register_resndata(NULL, name, 0,

					       NULL, 0, si, sizeof(*si));

	return IS_ERR(pd) ? PTR_ERR(pd) : 0;

}



device_initcall(sysfb_init);

arch/x86/kernel/sysfb_simplefb.c

0 → 100644
+95 −0
Original line number Diff line number Diff line 
/*

 * Generic System Framebuffers on x86

 * Copyright (c) 2012-2013 David Herrmann <dh.herrmann@gmail.com>

 *

 * This program is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License as published by the Free

 * Software Foundation; either version 2 of the License, or (at your option)

 * any later version.

 */



/*

 * simple-framebuffer probing

 * Try to convert "screen_info" into a "simple-framebuffer" compatible mode.

 * If the mode is incompatible, we return "false" and let the caller create

 * legacy nodes instead.

 */



#include <linux/err.h>

#include <linux/init.h>

#include <linux/kernel.h>

#include <linux/mm.h>

#include <linux/platform_data/simplefb.h>

#include <linux/platform_device.h>

#include <linux/screen_info.h>

#include <asm/sysfb.h>



static const char simplefb_resname[] = "BOOTFB";

static const struct simplefb_format formats[] = SIMPLEFB_FORMATS;



/* try parsing x86 screen_info into a simple-framebuffer mode struct */

__init bool parse_mode(const struct screen_info *si,

		       struct simplefb_platform_data *mode)

{

	const struct simplefb_format *f;

	__u8 type;

	unsigned int i;



	type = si->orig_video_isVGA;

	if (type != VIDEO_TYPE_VLFB && type != VIDEO_TYPE_EFI)

		return false;



	for (i = 0; i < ARRAY_SIZE(formats); ++i) {

		f = &formats[i];

		if (si->lfb_depth == f->bits_per_pixel &&

		    si->red_size == f->red.length &&

		    si->red_pos == f->red.offset &&

		    si->green_size == f->green.length &&

		    si->green_pos == f->green.offset &&

		    si->blue_size == f->blue.length &&

		    si->blue_pos == f->blue.offset &&

		    si->rsvd_size == f->transp.length &&

		    si->rsvd_pos == f->transp.offset) {

			mode->format = f->name;

			mode->width = si->lfb_width;

			mode->height = si->lfb_height;

			mode->stride = si->lfb_linelength;

			return true;

		}

	}



	return false;

}



__init int create_simplefb(const struct screen_info *si,

			   const struct simplefb_platform_data *mode)

{

	struct platform_device *pd;

	struct resource res;

	unsigned long len;



	/* don't use lfb_size as it may contain the whole VMEM instead of only

	 * the part that is occupied by the framebuffer */

	len = mode->height * mode->stride;

	len = PAGE_ALIGN(len);

	if (len > si->lfb_size << 16) {

		printk(KERN_WARNING "sysfb: VRAM smaller than advertised\n");

		return -EINVAL;

	}



	/* setup IORESOURCE_MEM as framebuffer memory */

	memset(&res, 0, sizeof(res));

	res.flags = IORESOURCE_MEM;

	res.name = simplefb_resname;

	res.start = si->lfb_base;

	res.end = si->lfb_base + len - 1;

	if (res.end <= res.start)

		return -EINVAL;



	pd = platform_device_register_resndata(NULL, "simple-framebuffer", 0,

					       &res, 1, mode, sizeof(*mode));

	if (IS_ERR(pd))

		return PTR_ERR(pd);



	return 0;

}