// 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/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 struct device *sysfb_parent_dev(const struct screen_info *si); 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 * @dev:	the device to check if non-NULL * * 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(struct device *dev){	struct screen_info *si = &screen_info;	struct device *parent; 	mutex_lock(&disable_lock);	parent = sysfb_parent_dev(si);	if (!dev || !parent || dev == parent) {		sysfb_unregister();		disabled = true;	}	mutex_unlock(&disable_lock);}EXPORT_SYMBOL_GPL(sysfb_disable); /** * sysfb_handles_screen_info() - reports if sysfb handles the global screen_info * * Callers can use sysfb_handles_screen_info() to determine whether the Generic * System Framebuffers (sysfb) can handle the global screen_info data structure * or not. Drivers might need this information to know if they have to setup the * system framebuffer, or if they have to delegate this action to sysfb instead. * * Returns: * True if sysfb handles the global screen_info data structure. */bool sysfb_handles_screen_info(void){	const struct screen_info *si = &screen_info; 	return !!screen_info_video_type(si);}EXPORT_SYMBOL_GPL(sysfb_handles_screen_info); #if defined(CONFIG_PCI)static bool sysfb_pci_dev_is_enabled(struct pci_dev *pdev){	/*	 * TODO: Try to integrate this code into the PCI subsystem	 */	int ret;	u16 command; 	ret = pci_read_config_word(pdev, PCI_COMMAND, &command);	if (ret != PCIBIOS_SUCCESSFUL)		return false;	if (!(command & PCI_COMMAND_MEMORY))		return false;	return true;}#elsestatic bool sysfb_pci_dev_is_enabled(struct pci_dev *pdev){	return false;}#endif static struct device *sysfb_parent_dev(const struct screen_info *si){	struct pci_dev *pdev; 	pdev = screen_info_pci_dev(si);	if (IS_ERR(pdev)) {		return ERR_CAST(pdev);	} else if (pdev) {		if (!sysfb_pci_dev_is_enabled(pdev)) {			pci_dev_put(pdev);			return ERR_PTR(-ENODEV);		}		return &pdev->dev;	} 	return NULL;} static __init int sysfb_init(void){	struct screen_info *si = &screen_info;	struct device *parent;	struct simplefb_platform_data mode;	const char *name;	bool compatible;	int ret = 0; 	screen_info_apply_fixups(); 	mutex_lock(&disable_lock);	if (disabled)		goto unlock_mutex; 	sysfb_apply_efi_quirks(); 	parent = sysfb_parent_dev(si);	if (IS_ERR(parent)) {		ret = PTR_ERR(parent);		goto unlock_mutex;	} 	/* try to create a simple-framebuffer device */	compatible = sysfb_parse_mode(si, &mode);	if (compatible) {		pd = sysfb_create_simplefb(si, &mode, parent);		if (!IS_ERR(pd))			goto put_device;	} 	/* 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 put_device;	} 	pd->dev.parent = parent; 	sysfb_set_efifb_fwnode(pd); 	ret = platform_device_add_data(pd, si, sizeof(*si));	if (ret)		goto err; 	ret = platform_device_add(pd);	if (ret)		goto err; 	goto put_device;err:	platform_device_put(pd);put_device:	put_device(parent);unlock_mutex:	mutex_unlock(&disable_lock);	return ret;} /* must execute after PCI subsystem for EFI quirks */device_initcall(sysfb_init);