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