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((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(dst, src, c);
49		dst += c;
50		src += c;
51
52		trailing = copy_to_user(buf, buffer, 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(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((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(src, buf, c);
120		if (trailing == c) {
121			err = -EFAULT;
122			break;
123		}
124		c -= trailing;
125
126		fb_memcpy_toio(dst, src, c);
127		dst += c;
128		src += c;
129		*ppos += c;
130		buf += c;
131		cnt += c;
132		count -= c;
133	}
134
135	kfree(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(vma->vm_flags);
164	vma->vm_page_prot = pgprot_framebuffer(vma->vm_page_prot, vma->vm_start,
165					       vma->vm_end, 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