diff mbox series

[2/2] efi: earlycon: Add support for generic framebuffers and move to fbdev subsystem

Message ID 20220728142824.3836-3-markuss.broks@gmail.com
State Superseded
Headers show
Series Add generic framebuffer support to EFI earlycon driver | expand

Commit Message

Markuss Broks July 28, 2022, 2:28 p.m. UTC
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@gmail.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

Comments

Arnd Bergmann July 28, 2022, 2:48 p.m. UTC | #1
On Thu, Jul 28, 2022 at 4:28 PM Markuss Broks <markuss.broks@gmail.com> 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.
>
> Signed-off-by: Markuss Broks <markuss.broks@gmail.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 ++++++++++++++++++

It looks like this is not actually related to fbdev, and since drivers are
moving from fbdev/simplefb towards drm/simpledrm, maybe it would be
better to put this into either drivers/gpu/drm/tiny/ or possibly
drivers/video/console to let this be used without enabling fbdev?

        Arnd
Markuss Broks July 28, 2022, 2:57 p.m. UTC | #2
Hi Arnd,

On 7/28/22 17:48, Arnd Bergmann wrote:
> On Thu, Jul 28, 2022 at 4:28 PM Markuss Broks <markuss.broks@gmail.com> 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.
>>
>> Signed-off-by: Markuss Broks <markuss.broks@gmail.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 ++++++++++++++++++
> 
> It looks like this is not actually related to fbdev, and since drivers are
> moving from fbdev/simplefb towards drm/simpledrm, maybe it would be
> better to put this into either drivers/gpu/drm/tiny/ or possibly
> drivers/video/console to let this be used without enabling fbdev?

Ideally this shouldn't depend on anything, because it isn't utilizing 
any of fbdev code and won't be utilizing any of drm/console code. I 
agree that either of those would be a better place for it, but which one 
do you think would suit more for this driver?

> 
>          Arnd

- Markuss
Arnd Bergmann July 28, 2022, 3:16 p.m. UTC | #3
On Thu, Jul 28, 2022 at 4:57 PM Markuss Broks <markuss.broks@gmail.com> wrote:
> On 7/28/22 17:48, Arnd Bergmann wrote:
> > On Thu, Jul 28, 2022 at 4:28 PM Markuss Broks <markuss.broks@gmail.com> 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.
> >>
> >> Signed-off-by: Markuss Broks <markuss.broks@gmail.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 ++++++++++++++++++
> >
> > It looks like this is not actually related to fbdev, and since drivers are
> > moving from fbdev/simplefb towards drm/simpledrm, maybe it would be
> > better to put this into either drivers/gpu/drm/tiny/ or possibly
> > drivers/video/console to let this be used without enabling fbdev?
>
> Ideally this shouldn't depend on anything, because it isn't utilizing
> any of fbdev code and won't be utilizing any of drm/console code. I
> agree that either of those would be a better place for it, but which one
> do you think would suit more for this driver?

I think ideally this would be integrated with simpledrm in the long run,
but I have no idea what that means in terms of future code changes.

Maybe Thomas Zimmermann has an idea here.

        Arnd
Andy Shevchenko July 28, 2022, 9:06 p.m. UTC | #4
On Thu, Jul 28, 2022 at 4:58 PM Markuss Broks <markuss.broks@gmail.com> wrote:
> On 7/28/22 17:39, Greg Kroah-Hartman wrote:
> > On Thu, Jul 28, 2022 at 05:28:19PM +0300, Markuss Broks wrote:

> >>   delete mode 100644 drivers/firmware/efi/earlycon.c
> >>   create mode 100644 drivers/video/fbdev/earlycon.c
> >
> > That should be a rename, not a delete/create, right?
>
> Should this change be split into two separate commits,
> one for moving the file and the second for making changes?

I think it's a pointer to use `git format-patch -M -C ...` when
preparing patches.
Andy Shevchenko July 28, 2022, 9:19 p.m. UTC | #5
On Thu, Jul 28, 2022 at 4:32 PM Markuss Broks <markuss.broks@gmail.com> 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.

...

> -               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).

If somebody passes those (legacy) options, what will happen?

...

>  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

This doesn't sound right. Previously on my configuration it was
selected automatically, now I need to select it explicitly? I mean
that for me EFI_EARLYCON should be selected by default as it was
before.

...

> +static int __init simplefb_earlycon_remap_fb(void)
> +{
> +       int is_ram;

+ blank line.

> +       /* 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;

Was it in the original code? Otherwise, I would go with plain conditional:

  if (region_intersects())
    base = ...
  else
    base = ...

> +       info.virt_base = memremap(info.phys_base, info.size,
> +                                 is_ram ? MEMREMAP_WB : MEMREMAP_WC);
> +
> +       return info.virt_base ? 0 : -ENOMEM;
> +}

...

> +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);
> +       }
> +}

Wondering if we already have something like this in DRM/fbdev and can
split into a generic helper.

...

> +       ret = sscanf(device->options, "%u,%u,%u", &info.x, &info.y, &info.depth);
> +       if (ret != 3)
> +               return -ENODEV;

Don't we have some standard template of this, something like XxYxD,
where X, Y, and D are respective decimal numbers?
kernel test robot July 28, 2022, 9:20 p.m. UTC | #6
Hi Markuss,

I love your patch! Yet something to improve:

[auto build test ERROR on tty/tty-testing]
[also build test ERROR on efi/next staging/staging-testing usb/usb-testing linus/master v5.19-rc8 next-20220728]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Markuss-Broks/Add-generic-framebuffer-support-to-EFI-earlycon-driver/20220728-223117
base:   https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git tty-testing
config: ia64-allmodconfig (https://download.01.org/0day-ci/archive/20220729/202207290523.Br8Zr7V3-lkp@intel.com/config)
compiler: ia64-linux-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/intel-lab-lkp/linux/commit/b6a59e731326deaa78f7dcbd97520e2eed2bc707
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Markuss-Broks/Add-generic-framebuffer-support-to-EFI-earlycon-driver/20220728-223117
        git checkout b6a59e731326deaa78f7dcbd97520e2eed2bc707
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=ia64 SHELL=/bin/bash drivers/video/fbdev/

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@intel.com>

All error/warnings (new ones prefixed by >>):

   drivers/video/fbdev/earlycon.c: In function 'simplefb_earlycon_map':
>> drivers/video/fbdev/earlycon.c:65:16: error: implicit declaration of function 'early_memremap_prot'; did you mean 'early_memremap'? [-Werror=implicit-function-declaration]
      65 |         return early_memremap_prot(info.phys_base + start, len, pgprot_val(fb_prot));
         |                ^~~~~~~~~~~~~~~~~~~
         |                early_memremap
>> drivers/video/fbdev/earlycon.c:65:16: warning: returning 'int' from a function with return type 'void *' makes pointer from integer without a cast [-Wint-conversion]
      65 |         return early_memremap_prot(info.phys_base + start, len, pgprot_val(fb_prot));
         |                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   cc1: some warnings being treated as errors
   {standard input}: Assembler messages:
   {standard input}:210: Error: Register number out of range 0..0
   {standard input}:211: Error: Register number out of range 0..0
   {standard input}:211: Warning: Use of 'mov' violates WAW dependency 'GR%, % in 1 - 127' (impliedf), specific resource number is 35
   {standard input}:211: Warning: Only the first path encountering the conflict is reported
   {standard input}:210: Warning: This is the location of the conflicting usage
   {standard input}:212: Error: Register number out of range 0..0
   {standard input}:212: Warning: Use of 'mov' violates WAW dependency 'GR%, % in 1 - 127' (impliedf), specific resource number is 35
   {standard input}:212: Warning: Only the first path encountering the conflict is reported
   {standard input}:210: Warning: This is the location of the conflicting usage
   {standard input}:212: Warning: Use of 'mov' violates WAW dependency 'GR%, % in 1 - 127' (impliedf), specific resource number is 35
   {standard input}:212: Warning: Only the first path encountering the conflict is reported
   {standard input}:211: Warning: This is the location of the conflicting usage
   {standard input}:214: Error: Register number out of range 0..0
   {standard input}:214: Warning: Use of 'mov' violates WAW dependency 'GR%, % in 1 - 127' (impliedf), specific resource number is 35
   {standard input}:214: Warning: Only the first path encountering the conflict is reported
   {standard input}:210: Warning: This is the location of the conflicting usage
   {standard input}:214: Warning: Use of 'mov' violates WAW dependency 'GR%, % in 1 - 127' (impliedf), specific resource number is 35
   {standard input}:214: Warning: Only the first path encountering the conflict is reported
   {standard input}:211: Warning: This is the location of the conflicting usage
   {standard input}:214: Warning: Use of 'mov' violates WAW dependency 'GR%, % in 1 - 127' (impliedf), specific resource number is 35
   {standard input}:214: Warning: Only the first path encountering the conflict is reported
   {standard input}:212: Warning: This is the location of the conflicting usage
   {standard input}:215: Error: Register number out of range 0..0
   {standard input}:215: Warning: Use of 'mov' violates WAW dependency 'GR%, % in 1 - 127' (impliedf), specific resource number is 35
   {standard input}:215: Warning: Only the first path encountering the conflict is reported
   {standard input}:210: Warning: This is the location of the conflicting usage
   {standard input}:215: Warning: Use of 'mov' violates WAW dependency 'GR%, % in 1 - 127' (impliedf), specific resource number is 35
   {standard input}:215: Warning: Only the first path encountering the conflict is reported
   {standard input}:211: Warning: This is the location of the conflicting usage
   {standard input}:215: Warning: Use of 'mov' violates WAW dependency 'GR%, % in 1 - 127' (impliedf), specific resource number is 35
   {standard input}:215: Warning: Only the first path encountering the conflict is reported
   {standard input}:212: Warning: This is the location of the conflicting usage
   {standard input}:215: Warning: Use of 'mov' violates WAW dependency 'GR%, % in 1 - 127' (impliedf), specific resource number is 35
   {standard input}:215: Warning: Only the first path encountering the conflict is reported
   {standard input}:214: Warning: This is the location of the conflicting usage
   {standard input}:216: Error: Register number out of range 0..0
   {standard input}:216: Warning: Use of 'mov' violates WAW dependency 'GR%, % in 1 - 127' (impliedf), specific resource number is 35
   {standard input}:216: Warning: Only the first path encountering the conflict is reported
   {standard input}:210: Warning: This is the location of the conflicting usage
   {standard input}:216: Warning: Use of 'mov' violates WAW dependency 'GR%, % in 1 - 127' (impliedf), specific resource number is 35
   {standard input}:216: Warning: Only the first path encountering the conflict is reported
   {standard input}:211: Warning: This is the location of the conflicting usage
   {standard input}:216: Warning: Use of 'mov' violates WAW dependency 'GR%, % in 1 - 127' (impliedf), specific resource number is 35
   {standard input}:216: Warning: Only the first path encountering the conflict is reported
   {standard input}:212: Warning: This is the location of the conflicting usage
   {standard input}:216: Warning: Use of 'mov' violates WAW dependency 'GR%, % in 1 - 127' (impliedf), specific resource number is 35
   {standard input}:216: Warning: Only the first path encountering the conflict is reported
   {standard input}:214: Warning: This is the location of the conflicting usage
   {standard input}:216: Warning: Use of 'mov' violates WAW dependency 'GR%, % in 1 - 127' (impliedf), specific resource number is 35
   {standard input}:216: Warning: Only the first path encountering the conflict is reported
   {standard input}:215: Warning: This is the location of the conflicting usage
   {standard input}:220: Error: Register number out of range 0..0
   {standard input}:376: Error: Register number out of range 0..1
   {standard input}:376: Warning: Use of 'mov' violates WAW dependency 'GR%, % in 1 - 127' (impliedf), specific resource number is 37
   {standard input}:376: Warning: Only the first path encountering the conflict is reported
   {standard input}:374: Warning: This is the location of the conflicting usage
   {standard input}:378: Error: Register number out of range 0..1
   {standard input}:378: Warning: Use of 'mov' violates WAW dependency 'GR%, % in 1 - 127' (impliedf), specific resource number is 37
   {standard input}:378: Warning: Only the first path encountering the conflict is reported
   {standard input}:374: Warning: This is the location of the conflicting usage
   {standard input}:378: Warning: Use of 'mov' violates WAW dependency 'GR%, % in 1 - 127' (impliedf), specific resource number is 37
   {standard input}:378: Warning: Only the first path encountering the conflict is reported
   {standard input}:376: Warning: This is the location of the conflicting usage
   {standard input}:379: Error: Register number out of range 0..1
   {standard input}:379: Warning: Use of 'mov' violates WAW dependency 'GR%, % in 1 - 127' (impliedf), specific resource number is 37
   {standard input}:379: Warning: Only the first path encountering the conflict is reported
   {standard input}:374: Warning: This is the location of the conflicting usage
   {standard input}:379: Warning: Use of 'mov' violates WAW dependency 'GR%, % in 1 - 127' (impliedf), specific resource number is 37
   {standard input}:379: Warning: Only the first path encountering the conflict is reported
   {standard input}:376: Warning: This is the location of the conflicting usage
   {standard input}:379: Warning: Use of 'mov' violates WAW dependency 'GR%, % in 1 - 127' (impliedf), specific resource number is 37
   {standard input}:379: Warning: Only the first path encountering the conflict is reported
   {standard input}:378: Warning: This is the location of the conflicting usage
   {standard input}:380: Error: Register number out of range 0..1
   {standard input}:380: Warning: Use of 'mov' violates WAW dependency 'GR%, % in 1 - 127' (impliedf), specific resource number is 37
   {standard input}:380: Warning: Only the first path encountering the conflict is reported
   {standard input}:374: Warning: This is the location of the conflicting usage
   {standard input}:380: Warning: Use of 'mov' violates WAW dependency 'GR%, % in 1 - 127' (impliedf), specific resource number is 37
   {standard input}:380: Warning: Only the first path encountering the conflict is reported
   {standard input}:376: Warning: This is the location of the conflicting usage
   {standard input}:380: Warning: Use of 'mov' violates WAW dependency 'GR%, % in 1 - 127' (impliedf), specific resource number is 37
   {standard input}:380: Warning: Only the first path encountering the conflict is reported
   {standard input}:378: Warning: This is the location of the conflicting usage
   {standard input}:380: Warning: Use of 'mov' violates WAW dependency 'GR%, % in 1 - 127' (impliedf), specific resource number is 37
   {standard input}:380: Warning: Only the first path encountering the conflict is reported
   {standard input}:379: Warning: This is the location of the conflicting usage
   {standard input}:383: Error: Register number out of range 0..1
   {standard input}:384: Error: Register number out of range 0..1
   {standard input}:384: Warning: Use of 'mov' violates WAW dependency 'GR%, % in 1 - 127' (impliedf), specific resource number is 37
   {standard input}:384: Warning: Only the first path encountering the conflict is reported
   {standard input}:383: Warning: This is the location of the conflicting usage


vim +65 drivers/video/fbdev/earlycon.c

    56	
    57	static __ref void *simplefb_earlycon_map(unsigned long start, unsigned long len)
    58	{
    59		pgprot_t fb_prot;
    60	
    61		if (info.virt_base)
    62			return info.virt_base + start;
    63	
    64		fb_prot = PAGE_KERNEL;
  > 65		return early_memremap_prot(info.phys_base + start, len, pgprot_val(fb_prot));
    66	}
    67
Andy Shevchenko July 30, 2022, 10:25 a.m. UTC | #7
On Sat, Jul 30, 2022 at 10:55 AM Markuss Broks <markuss.broks@gmail.com> wrote:
> On 7/29/22 00:19, Andy Shevchenko wrote:
> > On Thu, Jul 28, 2022 at 4:32 PM Markuss Broks <markuss.broks@gmail.com> wrote:

...

> I suppose we could use something like:
>
> if (region_intersects() == REGION_INTERSECTS)

Yes.

...

> >> +       ret = sscanf(device->options, "%u,%u,%u", &info.x, &info.y, &info.depth);
> >> +       if (ret != 3)
> >> +               return -ENODEV;
> >
> > Don't we have some standard template of this, something like XxYxD,
> > where X, Y, and D are respective decimal numbers?
>
> I'm not aware of this.

I believe we won't introduce more chaos in already existing formats of
one or another thing, so I prefer to be stuck with in practice use
(e.g. "1024x768x16" without quotes for x=1024, y=768, depth=16).
Markuss Broks July 30, 2022, 11:54 a.m. UTC | #8
Hi Andy,

On 7/29/22 00:19, Andy Shevchenko wrote:
> On Thu, Jul 28, 2022 at 4:32 PM Markuss Broks <markuss.broks@gmail.com> 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.
> 
> ...
> 
>> -               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).
> 
> If somebody passes those (legacy) options, what will happen?

Those would be ignored. Instead it would be automatically determined if 
framebuffer is located in RAM or in the I/O space.

> 
> ...
> 
>>   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
> 
> This doesn't sound right. Previously on my configuration it was
> selected automatically, now I need to select it explicitly? I mean
> that for me EFI_EARLYCON should be selected by default as it was
> before.

The problem I had with EFI_EARLYCON selected by default was that it 
would also carry fbdev with itself. Luckily, that's solved if it's moved 
to console subsystem.

> 
> ...
> 
>> +static int __init simplefb_earlycon_remap_fb(void)
>> +{
>> +       int is_ram;
> 
> + blank line.
> 
>> +       /* 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;
> 
> Was it in the original code? Otherwise, I would go with plain conditional:
> 
>    if (region_intersects())
>      base = ...
>    else
>      base = ...

It wasn't in original code. Original code assumed MEMREMAP_WC always
unless "ram" was specified as an option to efifb (e.g.
earlycon=efifb,ram). This code instead checks if the framebuffer is in 
RAM, and sets the mapping accordingly.

Another issue is that region_intersects() returns REGION_INTERSECTS 
(defined as 0) when true. I suppose we could use something like:

if (region_intersects() == REGION_INTERSECTS)
...

> 
>> +       info.virt_base = memremap(info.phys_base, info.size,
>> +                                 is_ram ? MEMREMAP_WB : MEMREMAP_WC);
>> +
>> +       return info.virt_base ? 0 : -ENOMEM;
>> +}
> 
> ...
> 
>> +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);
>> +       }
>> +}
> 
> Wondering if we already have something like this in DRM/fbdev and can
> split into a generic helper.
> 
> ...
> 
>> +       ret = sscanf(device->options, "%u,%u,%u", &info.x, &info.y, &info.depth);
>> +       if (ret != 3)
>> +               return -ENODEV;
> 
> Don't we have some standard template of this, something like XxYxD,
> where X, Y, and D are respective decimal numbers?

I'm not aware of this.

> 

-Markuss
Markuss Broks Aug. 6, 2022, 4:26 p.m. UTC | #9
Hi Greg,

On 7/28/22 18:01, Greg Kroah-Hartman wrote:
> On Thu, Jul 28, 2022 at 05:52:04PM +0300, Markuss Broks wrote:
>> Hi Greg,
>>
>> On 7/28/22 17:39, Greg Kroah-Hartman wrote:
>>> On Thu, Jul 28, 2022 at 05:28:19PM +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.
>>>>
>>>> Signed-off-by: Markuss Broks <markuss.broks@gmail.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
>>>
>>> That should be a rename, not a delete/create, right?
>>
>> Should this change be split into two separate commits,
>> one for moving the file and the second for making changes?
> 
> Git will show a rename and modification properly, if you use -M to git
> format-patch, so it should be fine.

It appears that there are so many changes Git would refuse to make it a 
"move" no matter what I do. What should be done here: should it be two 
separate commits for move/change or should it just be kept as delete/create?

- Markuss
Greg KH Aug. 7, 2022, 6:53 a.m. UTC | #10
On Sat, Aug 06, 2022 at 07:26:07PM +0300, Markuss Broks wrote:
> Hi Greg,
> 
> On 7/28/22 18:01, Greg Kroah-Hartman wrote:
> > On Thu, Jul 28, 2022 at 05:52:04PM +0300, Markuss Broks wrote:
> > > Hi Greg,
> > > 
> > > On 7/28/22 17:39, Greg Kroah-Hartman wrote:
> > > > On Thu, Jul 28, 2022 at 05:28:19PM +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.
> > > > > 
> > > > > Signed-off-by: Markuss Broks <markuss.broks@gmail.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
> > > > 
> > > > That should be a rename, not a delete/create, right?
> > > 
> > > Should this change be split into two separate commits,
> > > one for moving the file and the second for making changes?
> > 
> > Git will show a rename and modification properly, if you use -M to git
> > format-patch, so it should be fine.
> 
> It appears that there are so many changes Git would refuse to make it a
> "move" no matter what I do. What should be done here: should it be two
> separate commits for move/change or should it just be kept as delete/create?

One commit to move the file, and then add your changes on top of it
might be the easiest to review, right?

thanks,

greg k-h
Daniel Vetter Sept. 6, 2022, 7:39 p.m. UTC | #11
On Sun, Aug 07, 2022 at 08:53:14AM +0200, Greg Kroah-Hartman wrote:
> On Sat, Aug 06, 2022 at 07:26:07PM +0300, Markuss Broks wrote:
> > Hi Greg,
> > 
> > On 7/28/22 18:01, Greg Kroah-Hartman wrote:
> > > On Thu, Jul 28, 2022 at 05:52:04PM +0300, Markuss Broks wrote:
> > > > Hi Greg,
> > > > 
> > > > On 7/28/22 17:39, Greg Kroah-Hartman wrote:
> > > > > On Thu, Jul 28, 2022 at 05:28:19PM +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.
> > > > > > 
> > > > > > Signed-off-by: Markuss Broks <markuss.broks@gmail.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
> > > > > 
> > > > > That should be a rename, not a delete/create, right?
> > > > 
> > > > Should this change be split into two separate commits,
> > > > one for moving the file and the second for making changes?
> > > 
> > > Git will show a rename and modification properly, if you use -M to git
> > > format-patch, so it should be fine.
> > 
> > It appears that there are so many changes Git would refuse to make it a
> > "move" no matter what I do. What should be done here: should it be two
> > separate commits for move/change or should it just be kept as delete/create?
> 
> One commit to move the file, and then add your changes on top of it
> might be the easiest to review, right?

+1

I think this should be a least
- commit to move the file, as unchanged as possible
- commit to auto-select the right mapping mode (or maybe that's only in
  v2)
- actual change to add the simplefb support with a clearly readable diff

But also video/console is for Greg to maintain, I'm trying hard to not go
even more stupid :-)
-Daniel
diff mbox series

Patch

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@gmail.com>
+S:	Maintained
+F:	drivers/video/fbdev/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..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@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)
+{
+	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