Hi
Any comments on this?
On Thu, Jul 4, 2013 at 2:25 PM, David Herrmann <dh.herrmann@xxxxxxxxx> wrote:
> 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: David Herrmann <dh.herrmann@xxxxxxxxx>
> ---
> arch/x86/Kconfig | 26 +++++++++++
> arch/x86/include/asm/sysfb.h | 41 +++++++++++++++++
> arch/x86/kernel/Makefile | 2 +
> arch/x86/kernel/sysfb.c | 71 ++++++++++++++++++++++++++++++
> arch/x86/kernel/sysfb_simplefb.c | 95 ++++++++++++++++++++++++++++++++++++++++
> 5 files changed, 235 insertions(+)
> create mode 100644 arch/x86/include/asm/sysfb.h
> create mode 100644 arch/x86/kernel/sysfb.c
> create mode 100644 arch/x86/kernel/sysfb_simplefb.c
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index fe120da..54a93a5 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -2255,6 +2255,32 @@ 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
>
>
> diff --git a/arch/x86/include/asm/sysfb.h b/arch/x86/include/asm/sysfb.h
> new file mode 100644
> index 0000000..2395fe0
> --- /dev/null
> +++ b/arch/x86/include/asm/sysfb.h
> @@ -0,0 +1,41 @@
> +#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@xxxxxxxxx>
> + *
> + * 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 */
> diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
> index 7bd3bd3..c5e7677 100644
> --- a/arch/x86/kernel/Makefile
> +++ b/arch/x86/kernel/Makefile
> @@ -100,6 +100,8 @@ 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
>
> diff --git a/arch/x86/kernel/sysfb.c b/arch/x86/kernel/sysfb.c
> new file mode 100644
> index 0000000..7f30e19
> --- /dev/null
> +++ b/arch/x86/kernel/sysfb.c
> @@ -0,0 +1,71 @@
> +/*
> + * Generic System Framebuffers on x86
> + * Copyright (c) 2012-2013 David Herrmann <dh.herrmann@xxxxxxxxx>
> + *
> + * 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);
> diff --git a/arch/x86/kernel/sysfb_simplefb.c b/arch/x86/kernel/sysfb_simplefb.c
> new file mode 100644
> index 0000000..22513e9
> --- /dev/null
> +++ b/arch/x86/kernel/sysfb_simplefb.c
> @@ -0,0 +1,95 @@
> +/*
> + * Generic System Framebuffers on x86
> + * Copyright (c) 2012-2013 David Herrmann <dh.herrmann@xxxxxxxxx>
> + *
> + * 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;
> +}
> --
> 1.8.3.2
>
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