// 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 = &sysfb_primary_display.screen; 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 = &sysfb_primary_display.screen; 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; } #else static 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 sysfb_display_info *dpy = &sysfb_primary_display; struct screen_info *si = &dpy->screen; struct device *parent; unsigned int type; 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(si); 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; } type = screen_info_video_type(si); /* if the FB is incompatible, create a legacy framebuffer device */ switch (type) { case VIDEO_TYPE_EGAC: name = "ega-framebuffer"; break; case VIDEO_TYPE_VGAC: name = "vga-framebuffer"; break; case VIDEO_TYPE_VLFB: name = "vesa-framebuffer"; break; case VIDEO_TYPE_EFI: name = "efi-framebuffer"; break; default: name = "platform-framebuffer"; break; } pd = platform_device_alloc(name, 0); if (!pd) { ret = -ENOMEM; goto put_device; } pd->dev.parent = parent; sysfb_set_efifb_fwnode(si, pd); ret = platform_device_add_data(pd, dpy, sizeof(*dpy)); 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);
