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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Generic System Framebuffers
* Copyright (c) 2012-2013 David Herrmann <dh.herrmann@gmail.com>
*/
/*
* Simple-Framebuffer support
* 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_SYSFB_SIMPLEFB is not selected, 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 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 <linux/sysfb.h>
static struct platform_device *pd;
static DEFINE_MUTEX(disable_lock);
static bool disabled;
static bool sysfb_unregister(void)
{
if (IS_ERR_OR_NULL(pd))
return false;
platform_device_unregister(pd);
pd = NULL;
return true;
}
/**
* sysfb_disable() - disable the Generic System Framebuffers support
*
* This disables the registration of system framebuffer devices that match the
* generic drivers that make use of the system framebuffer set up by firmware.
*
* It also unregisters a device if this was already registered by sysfb_init().
*
* Context: The function can sleep. A @disable_lock mutex is acquired to serialize
* against sysfb_init(), that registers a system framebuffer device.
*/
void sysfb_disable(void)
{
mutex_lock(&disable_lock);
sysfb_unregister();
disabled = true;
mutex_unlock(&disable_lock);
}
EXPORT_SYMBOL_GPL(sysfb_disable);
static __init int sysfb_init(void)
{
struct screen_info *si = &screen_info;
struct simplefb_platform_data mode;
const char *name;
bool compatible;
int ret = 0;
mutex_lock(&disable_lock);
if (disabled)
goto unlock_mutex;
/* try to create a simple-framebuffer device */
compatible = sysfb_parse_mode(si, &mode);
if (compatible) {
pd = sysfb_create_simplefb(si, &mode);
if (!IS_ERR(pd))
goto unlock_mutex;
}
/* 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 if (si->orig_video_isVGA == VIDEO_TYPE_VGAC)
name = "vga-framebuffer";
else if (si->orig_video_isVGA == VIDEO_TYPE_EGAC)
name = "ega-framebuffer";
else
name = "platform-framebuffer";
pd = platform_device_alloc(name, 0);
if (!pd) {
ret = -ENOMEM;
goto unlock_mutex;
}
sysfb_apply_efi_quirks(pd);
ret = platform_device_add_data(pd, si, sizeof(*si));
if (ret)
goto err;
ret = platform_device_add(pd);
if (ret)
goto err;
goto unlock_mutex;
err:
platform_device_put(pd);
unlock_mutex:
mutex_unlock(&disable_lock);
return ret;
}
/* must execute after PCI subsystem for EFI quirks */
device_initcall(sysfb_init);
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