1// SPDX-License-Identifier: GPL-2.0
2
3#include <linux/fb.h>
4#include <linux/module.h>
5#include <linux/uaccess.h>
6
7ssize_t fb_io_read(struct fb_info *info, char __user *buf, size_t count, loff_t *ppos)
8{
9 unsigned long p = *ppos;
10 u8 *buffer, *dst;
11 u8 __iomem *src;
12 int c, cnt = 0, err = 0;
13 unsigned long total_size, trailing;
14
15 if (info->flags & FBINFO_VIRTFB)
16 fb_warn_once(info, "Framebuffer is not in I/O address space.");
17
18 if (!info->screen_base)
19 return -ENODEV;
20
21 total_size = info->screen_size;
22
23 if (total_size == 0)
24 total_size = info->fix.smem_len;
25
26 if (p >= total_size)
27 return 0;
28
29 if (count >= total_size)
30 count = total_size;
31
32 if (count + p > total_size)
33 count = total_size - p;
34
35 buffer = kmalloc(size: (count > PAGE_SIZE) ? PAGE_SIZE : count,
36 GFP_KERNEL);
37 if (!buffer)
38 return -ENOMEM;
39
40 src = (u8 __iomem *) (info->screen_base + p);
41
42 if (info->fbops->fb_sync)
43 info->fbops->fb_sync(info);
44
45 while (count) {
46 c = (count > PAGE_SIZE) ? PAGE_SIZE : count;
47 dst = buffer;
48 fb_memcpy_fromio(to: dst, from: src, n: c);
49 dst += c;
50 src += c;
51
52 trailing = copy_to_user(to: buf, from: buffer, n: c);
53 if (trailing == c) {
54 err = -EFAULT;
55 break;
56 }
57 c -= trailing;
58
59 *ppos += c;
60 buf += c;
61 cnt += c;
62 count -= c;
63 }
64
65 kfree(objp: buffer);
66
67 return cnt ? cnt : err;
68}
69EXPORT_SYMBOL(fb_io_read);
70
71ssize_t fb_io_write(struct fb_info *info, const char __user *buf, size_t count, loff_t *ppos)
72{
73 unsigned long p = *ppos;
74 u8 *buffer, *src;
75 u8 __iomem *dst;
76 int c, cnt = 0, err = 0;
77 unsigned long total_size, trailing;
78
79 if (info->flags & FBINFO_VIRTFB)
80 fb_warn_once(info, "Framebuffer is not in I/O address space.");
81
82 if (!info->screen_base)
83 return -ENODEV;
84
85 total_size = info->screen_size;
86
87 if (total_size == 0)
88 total_size = info->fix.smem_len;
89
90 if (p > total_size)
91 return -EFBIG;
92
93 if (count > total_size) {
94 err = -EFBIG;
95 count = total_size;
96 }
97
98 if (count + p > total_size) {
99 if (!err)
100 err = -ENOSPC;
101
102 count = total_size - p;
103 }
104
105 buffer = kmalloc(size: (count > PAGE_SIZE) ? PAGE_SIZE : count,
106 GFP_KERNEL);
107 if (!buffer)
108 return -ENOMEM;
109
110 dst = (u8 __iomem *) (info->screen_base + p);
111
112 if (info->fbops->fb_sync)
113 info->fbops->fb_sync(info);
114
115 while (count) {
116 c = (count > PAGE_SIZE) ? PAGE_SIZE : count;
117 src = buffer;
118
119 trailing = copy_from_user(to: src, from: buf, n: c);
120 if (trailing == c) {
121 err = -EFAULT;
122 break;
123 }
124 c -= trailing;
125
126 fb_memcpy_toio(to: dst, from: src, n: c);
127 dst += c;
128 src += c;
129 *ppos += c;
130 buf += c;
131 cnt += c;
132 count -= c;
133 }
134
135 kfree(objp: buffer);
136
137 return (cnt) ? cnt : err;
138}
139EXPORT_SYMBOL(fb_io_write);
140
141int fb_io_mmap(struct fb_info *info, struct vm_area_struct *vma)
142{
143 unsigned long start = info->fix.smem_start;
144 u32 len = info->fix.smem_len;
145 unsigned long mmio_pgoff = PAGE_ALIGN((start & ~PAGE_MASK) + len) >> PAGE_SHIFT;
146
147 if (info->flags & FBINFO_VIRTFB)
148 fb_warn_once(info, "Framebuffer is not in I/O address space.");
149
150 /*
151 * This can be either the framebuffer mapping, or if pgoff points
152 * past it, the mmio mapping.
153 */
154 if (vma->vm_pgoff >= mmio_pgoff) {
155 if (info->var.accel_flags)
156 return -EINVAL;
157
158 vma->vm_pgoff -= mmio_pgoff;
159 start = info->fix.mmio_start;
160 len = info->fix.mmio_len;
161 }
162
163 vma->vm_page_prot = vm_get_page_prot(vm_flags: vma->vm_flags);
164 vma->vm_page_prot = pgprot_framebuffer(prot: vma->vm_page_prot, vm_start: vma->vm_start,
165 vm_end: vma->vm_end, offset: start);
166
167 return vm_iomap_memory(vma, start, len);
168}
169EXPORT_SYMBOL(fb_io_mmap);
170
171MODULE_DESCRIPTION("Fbdev helpers for framebuffers in I/O memory");
172MODULE_LICENSE("GPL");
173

source code of linux/drivers/video/fbdev/core/fb_io_fops.c