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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Generic System Framebuffers
4 * Copyright (c) 2012-2013 David Herrmann <dh.herrmann@gmail.com>
5 */
6
7/*
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.
18 *
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.
22 *
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.
26 */
27
28#include <linux/err.h>
29#include <linux/init.h>
30#include <linux/kernel.h>
31#include <linux/mm.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>
37
38static struct platform_device *pd;
39static DEFINE_MUTEX(disable_lock);
40static bool disabled;
41
42static bool sysfb_unregister(void)
43{
44 if (IS_ERR_OR_NULL(pd))
45 return false;
46
47 platform_device_unregister(pd);
48 pd = NULL;
49
50 return true;
51}
52
53/**
54 * sysfb_disable() - disable the Generic System Framebuffers support
55 *
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.
58 *
59 * It also unregisters a device if this was already registered by sysfb_init().
60 *
61 * Context: The function can sleep. A @disable_lock mutex is acquired to serialize
62 * against sysfb_init(), that registers a system framebuffer device.
63 */
64void sysfb_disable(void)
65{
66 mutex_lock(&disable_lock);
67 sysfb_unregister();
68 disabled = true;
69 mutex_unlock(&disable_lock);
70}
71EXPORT_SYMBOL_GPL(sysfb_disable);
72
73#if defined(CONFIG_PCI)
74static __init bool sysfb_pci_dev_is_enabled(struct pci_dev *pdev)
75{
76 /*
77 * TODO: Try to integrate this code into the PCI subsystem
78 */
79 int ret;
80 u16 command;
81
82 ret = pci_read_config_word(pdev, PCI_COMMAND, &command);
83 if (ret != PCIBIOS_SUCCESSFUL)
84 return false;
85 if (!(command & PCI_COMMAND_MEMORY))
86 return false;
87 return true;
88}
89#else
90static __init bool sysfb_pci_dev_is_enabled(struct pci_dev *pdev)
91{
92 return false;
93}
94#endif
95
96static __init struct device *sysfb_parent_dev(const struct screen_info *si)
97{
98 struct pci_dev *pdev;
99
100 pdev = screen_info_pci_dev(si);
101 if (IS_ERR(pdev)) {
102 return ERR_CAST(pdev);
103 } else if (pdev) {
104 if (!sysfb_pci_dev_is_enabled(pdev)) {
105 pci_dev_put(pdev);
106 return ERR_PTR(-ENODEV);
107 }
108 return &pdev->dev;
109 }
110
111 return NULL;
112}
113
114static __init int sysfb_init(void)
115{
116 struct screen_info *si = &screen_info;
117 struct device *parent;
118 struct simplefb_platform_data mode;
119 const char *name;
120 bool compatible;
121 int ret = 0;
122
123 screen_info_apply_fixups();
124
125 mutex_lock(&disable_lock);
126 if (disabled)
127 goto unlock_mutex;
128
129 sysfb_apply_efi_quirks();
130
131 parent = sysfb_parent_dev(si);
132 if (IS_ERR(parent)) {
133 ret = PTR_ERR(parent);
134 goto unlock_mutex;
135 }
136
137 /* try to create a simple-framebuffer device */
138 compatible = sysfb_parse_mode(si, &mode);
139 if (compatible) {
140 pd = sysfb_create_simplefb(si, &mode, parent);
141 if (!IS_ERR(pd))
142 goto put_device;
143 }
144
145 /* if the FB is incompatible, create a legacy framebuffer device */
146 if (si->orig_video_isVGA == VIDEO_TYPE_EFI)
147 name = "efi-framebuffer";
148 else if (si->orig_video_isVGA == VIDEO_TYPE_VLFB)
149 name = "vesa-framebuffer";
150 else if (si->orig_video_isVGA == VIDEO_TYPE_VGAC)
151 name = "vga-framebuffer";
152 else if (si->orig_video_isVGA == VIDEO_TYPE_EGAC)
153 name = "ega-framebuffer";
154 else
155 name = "platform-framebuffer";
156
157 pd = platform_device_alloc(name, 0);
158 if (!pd) {
159 ret = -ENOMEM;
160 goto put_device;
161 }
162
163 pd->dev.parent = parent;
164
165 sysfb_set_efifb_fwnode(pd);
166
167 ret = platform_device_add_data(pd, si, sizeof(*si));
168 if (ret)
169 goto err;
170
171 ret = platform_device_add(pd);
172 if (ret)
173 goto err;
174
175 goto put_device;
176err:
177 platform_device_put(pd);
178put_device:
179 put_device(parent);
180unlock_mutex:
181 mutex_unlock(&disable_lock);
182 return ret;
183}
184
185/* must execute after PCI subsystem for EFI quirks */
186device_initcall(sysfb_init);