projects/linux·blob assoc-array-fixes · refs

225 lines · 5.6 KiB

1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Generic System Framebuffers
4 * Copyright (c) 2012-2013 David Herrmann <[email protected]>
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 struct device *sysfb_parent_dev(const struct screen_info *si);
43
44static bool sysfb_unregister(void)
45{
46 if (IS_ERR_OR_NULL(pd))
47 return false;
48
49 platform_device_unregister(pd);
50 pd = NULL;
51
52 return true;
53}
54
55/**
56 * sysfb_disable() - disable the Generic System Framebuffers support
57 * @dev: the device to check if non-NULL
58 *
59 * This disables the registration of system framebuffer devices that match the
60 * generic drivers that make use of the system framebuffer set up by firmware.
61 *
62 * It also unregisters a device if this was already registered by sysfb_init().
63 *
64 * Context: The function can sleep. A @disable_lock mutex is acquired to serialize
65 * against sysfb_init(), that registers a system framebuffer device.
66 */
67void sysfb_disable(struct device *dev)
68{
69 struct screen_info *si = &sysfb_primary_display.screen;
70 struct device *parent;
71
72 mutex_lock(&disable_lock);
73 parent = sysfb_parent_dev(si);
74 if (!dev || !parent || dev == parent) {
75 sysfb_unregister();
76 disabled = true;
77 }
78 mutex_unlock(&disable_lock);
79}
80EXPORT_SYMBOL_GPL(sysfb_disable);
81
82/**
83 * sysfb_handles_screen_info() - reports if sysfb handles the global screen_info
84 *
85 * Callers can use sysfb_handles_screen_info() to determine whether the Generic
86 * System Framebuffers (sysfb) can handle the global screen_info data structure
87 * or not. Drivers might need this information to know if they have to setup the
88 * system framebuffer, or if they have to delegate this action to sysfb instead.
89 *
90 * Returns:
91 * True if sysfb handles the global screen_info data structure.
92 */
93bool sysfb_handles_screen_info(void)
94{
95 const struct screen_info *si = &sysfb_primary_display.screen;
96
97 return !!screen_info_video_type(si);
98}
99EXPORT_SYMBOL_GPL(sysfb_handles_screen_info);
100
101#if defined(CONFIG_PCI)
102static bool sysfb_pci_dev_is_enabled(struct pci_dev *pdev)
103{
104 /*
105 * TODO: Try to integrate this code into the PCI subsystem
106 */
107 int ret;
108 u16 command;
109
110 ret = pci_read_config_word(pdev, PCI_COMMAND, &command);
111 if (ret != PCIBIOS_SUCCESSFUL)
112 return false;
113 if (!(command & PCI_COMMAND_MEMORY))
114 return false;
115 return true;
116}
117#else
118static bool sysfb_pci_dev_is_enabled(struct pci_dev *pdev)
119{
120 return false;
121}
122#endif
123
124static struct device *sysfb_parent_dev(const struct screen_info *si)
125{
126 struct pci_dev *pdev;
127
128 pdev = screen_info_pci_dev(si);
129 if (IS_ERR(pdev)) {
130 return ERR_CAST(pdev);
131 } else if (pdev) {
132 if (!sysfb_pci_dev_is_enabled(pdev)) {
133 pci_dev_put(pdev);
134 return ERR_PTR(-ENODEV);
135 }
136 return &pdev->dev;
137 }
138
139 return NULL;
140}
141
142static __init int sysfb_init(void)
143{
144 struct sysfb_display_info *dpy = &sysfb_primary_display;
145 struct screen_info *si = &dpy->screen;
146 struct device *parent;
147 unsigned int type;
148 struct simplefb_platform_data mode;
149 const char *name;
150 bool compatible;
151 int ret = 0;
152
153 screen_info_apply_fixups();
154
155 mutex_lock(&disable_lock);
156 if (disabled)
157 goto unlock_mutex;
158
159 sysfb_apply_efi_quirks(si);
160
161 parent = sysfb_parent_dev(si);
162 if (IS_ERR(parent)) {
163 ret = PTR_ERR(parent);
164 goto unlock_mutex;
165 }
166
167 /* try to create a simple-framebuffer device */
168 compatible = sysfb_parse_mode(si, &mode);
169 if (compatible) {
170 pd = sysfb_create_simplefb(si, &mode, parent);
171 if (!IS_ERR(pd))
172 goto put_device;
173 }
174
175 type = screen_info_video_type(si);
176
177 /* if the FB is incompatible, create a legacy framebuffer device */
178 switch (type) {
179 case VIDEO_TYPE_EGAC:
180 name = "ega-framebuffer";
181 break;
182 case VIDEO_TYPE_VGAC:
183 name = "vga-framebuffer";
184 break;
185 case VIDEO_TYPE_VLFB:
186 name = "vesa-framebuffer";
187 break;
188 case VIDEO_TYPE_EFI:
189 name = "efi-framebuffer";
190 break;
191 default:
192 name = "platform-framebuffer";
193 break;
194 }
195
196 pd = platform_device_alloc(name, 0);
197 if (!pd) {
198 ret = -ENOMEM;
199 goto put_device;
200 }
201
202 pd->dev.parent = parent;
203
204 sysfb_set_efifb_fwnode(si, pd);
205
206 ret = platform_device_add_data(pd, dpy, sizeof(*dpy));
207 if (ret)
208 goto err;
209
210 ret = platform_device_add(pd);
211 if (ret)
212 goto err;
213
214 goto put_device;
215err:
216 platform_device_put(pd);
217put_device:
218 put_device(parent);
219unlock_mutex:
220 mutex_unlock(&disable_lock);
221 return ret;
222}
223
224/* must execute after PCI subsystem for EFI quirks */
225device_initcall(sysfb_init);