1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * Generic System Framebuffers
4 * Copyright (c) 2012-2013 David Herrmann <dh.herrmann@gmail.com>
8 * Simple-Framebuffer support
9 * Create a platform-device for any available boot framebuffer. The
10 * simple-framebuffer platform device is already available on DT systems, so
11 * this module parses the global "screen_info" object and creates a suitable
12 * platform device compatible with the "simple-framebuffer" DT object. If
13 * the framebuffer is incompatible, we instead create a legacy
14 * "vesa-framebuffer", "efi-framebuffer" or "platform-framebuffer" device and
15 * pass the screen_info as platform_data. This allows legacy drivers
16 * to pick these devices up without messing with simple-framebuffer drivers.
17 * The global "screen_info" is still valid at all times.
19 * If CONFIG_SYSFB_SIMPLEFB is not selected, never register "simple-framebuffer"
20 * platform devices, but only use legacy framebuffer devices for
21 * backwards compatibility.
23 * TODO: We set the dev_id field of all platform-devices to 0. This allows
24 * other OF/DT parsers to create such devices, too. However, they must
25 * start at offset 1 for this to work.
28 #include <linux/err.h>
29 #include <linux/init.h>
30 #include <linux/kernel.h>
32 #include <linux/pci.h>
33 #include <linux/platform_data/simplefb.h>
34 #include <linux/platform_device.h>
35 #include <linux/screen_info.h>
36 #include <linux/sysfb.h>
38 static struct platform_device *pd;
39 static DEFINE_MUTEX(disable_lock);
42 static bool sysfb_unregister(void)
44 if (IS_ERR_OR_NULL(pd))
47 platform_device_unregister(pd);
54 * sysfb_disable() - disable the Generic System Framebuffers support
56 * This disables the registration of system framebuffer devices that match the
57 * generic drivers that make use of the system framebuffer set up by firmware.
59 * It also unregisters a device if this was already registered by sysfb_init().
61 * Context: The function can sleep. A @disable_lock mutex is acquired to serialize
62 * against sysfb_init(), that registers a system framebuffer device.
64 void sysfb_disable(void)
66 mutex_lock(&disable_lock);
69 mutex_unlock(&disable_lock);
71 EXPORT_SYMBOL_GPL(sysfb_disable);
73 #if defined(CONFIG_PCI)
74 static __init bool sysfb_pci_dev_is_enabled(struct pci_dev *pdev)
77 * TODO: Try to integrate this code into the PCI subsystem
82 ret = pci_read_config_word(pdev, PCI_COMMAND, &command);
83 if (ret != PCIBIOS_SUCCESSFUL)
85 if (!(command & PCI_COMMAND_MEMORY))
90 static __init bool sysfb_pci_dev_is_enabled(struct pci_dev *pdev)
96 static __init struct device *sysfb_parent_dev(const struct screen_info *si)
100 pdev = screen_info_pci_dev(si);
102 return ERR_CAST(pdev);
104 if (!sysfb_pci_dev_is_enabled(pdev))
105 return ERR_PTR(-ENODEV);
112 static __init int sysfb_init(void)
114 struct screen_info *si = &screen_info;
115 struct device *parent;
116 struct simplefb_platform_data mode;
121 screen_info_apply_fixups();
123 mutex_lock(&disable_lock);
127 sysfb_apply_efi_quirks();
129 parent = sysfb_parent_dev(si);
130 if (IS_ERR(parent)) {
131 ret = PTR_ERR(parent);
135 /* try to create a simple-framebuffer device */
136 compatible = sysfb_parse_mode(si, &mode);
138 pd = sysfb_create_simplefb(si, &mode, parent);
143 /* if the FB is incompatible, create a legacy framebuffer device */
144 if (si->orig_video_isVGA == VIDEO_TYPE_EFI)
145 name = "efi-framebuffer";
146 else if (si->orig_video_isVGA == VIDEO_TYPE_VLFB)
147 name = "vesa-framebuffer";
148 else if (si->orig_video_isVGA == VIDEO_TYPE_VGAC)
149 name = "vga-framebuffer";
150 else if (si->orig_video_isVGA == VIDEO_TYPE_EGAC)
151 name = "ega-framebuffer";
153 name = "platform-framebuffer";
155 pd = platform_device_alloc(name, 0);
161 pd->dev.parent = parent;
163 sysfb_set_efifb_fwnode(pd);
165 ret = platform_device_add_data(pd, si, sizeof(*si));
169 ret = platform_device_add(pd);
175 platform_device_put(pd);
177 mutex_unlock(&disable_lock);
181 /* must execute after PCI subsystem for EFI quirks */
182 device_initcall(sysfb_init);