linux/drivers/firmware/sysfb.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Generic System Framebuffers
 * Copyright (c) 2012-2013 David Herrmann <[email protected]>
 */

/*
 * 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/pci.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)
{ … }

/**
 * 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)
{ … }
EXPORT_SYMBOL_GPL(…);

#if defined(CONFIG_PCI)
static __init bool sysfb_pci_dev_is_enabled(struct pci_dev *pdev)
{ … }
#else
static __init bool sysfb_pci_dev_is_enabled(struct pci_dev *pdev)
{
	return false;
}
#endif

static __init struct device *sysfb_parent_dev(const struct screen_info *si)
{ … }

static __init int sysfb_init(void)
{ … }

/* must execute after PCI subsystem for EFI quirks */
device_initcall(sysfb_init);