fb_info.c

 1// SPDX-License-Identifier: GPL-2.0-or-later
 2
 3#include <linux/export.h>
 4#include <linux/fb.h>
 5#include <linux/mutex.h>
 6#include <linux/slab.h>
 7
 8/**
 9 * framebuffer_alloc - creates a new frame buffer info structure
10 *
11 * @size: size of driver private data, can be zero
12 * @dev: pointer to the device for this fb, this can be NULL
13 *
14 * Creates a new frame buffer info structure. Also reserves @size bytes
15 * for driver private data (info->par). info->par (if any) will be
16 * aligned to sizeof(long). The new instances of struct fb_info and
17 * the driver private data are both cleared to zero.
18 *
19 * Returns the new structure, or NULL if an error occurred.
20 *
21 */
22struct fb_info *framebuffer_alloc(size_t size, struct device *dev)
23{
24#define BYTES_PER_LONG (BITS_PER_LONG/8)
25#define PADDING (BYTES_PER_LONG - (sizeof(struct fb_info) % BYTES_PER_LONG))
26	int fb_info_size = sizeof(struct fb_info);
27	struct fb_info *info;
28	char *p;
29
30	if (size)
31		fb_info_size += PADDING;
32
33	p = kzalloc(fb_info_size + size, GFP_KERNEL);
34
35	if (!p)
36		return NULL;
37
38	info = (struct fb_info *) p;
39
40	if (size)
41		info->par = p + fb_info_size;
42
43	info->device = dev;
44	info->fbcon_rotate_hint = -1;
45	info->blank = FB_BLANK_UNBLANK;
46
47#if IS_ENABLED(CONFIG_FB_BACKLIGHT)
48	mutex_init(&info->bl_curve_mutex);
49#endif
50
51	return info;
52#undef PADDING
53#undef BYTES_PER_LONG
54}
55EXPORT_SYMBOL(framebuffer_alloc);
56
57/**
58 * framebuffer_release - marks the structure available for freeing
59 *
60 * @info: frame buffer info structure
61 *
62 * Drop the reference count of the device embedded in the
63 * framebuffer info structure.
64 *
65 */
66void framebuffer_release(struct fb_info *info)
67{
68	if (!info)
69		return;
70
71	if (WARN_ON(refcount_read(&info->count)))
72		return;
73
74#if IS_ENABLED(CONFIG_FB_BACKLIGHT)
75	mutex_destroy(&info->bl_curve_mutex);
76#endif
77
78	kfree(info);
79}
80EXPORT_SYMBOL(framebuffer_release);