xref: /linux/drivers/video/fbdev/core/fb_io_fops.c (revision 0ea5c948cb64bab5bc7a5516774eb8536f05aa0d)
1 // SPDX-License-Identifier: GPL-2.0
2 
3 #include <linux/fb.h>
4 #include <linux/module.h>
5 #include <linux/uaccess.h>
6 
fb_io_read(struct fb_info * info,char __user * buf,size_t count,loff_t * ppos)7 ssize_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 }
69 EXPORT_SYMBOL(fb_io_read);
70 
fb_io_write(struct fb_info * info,const char __user * buf,size_t count,loff_t * ppos)71 ssize_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 }
139 EXPORT_SYMBOL(fb_io_write);
140 
fb_io_mmap(struct fb_info * info,struct vm_area_struct * vma)141 int 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 }
169 EXPORT_SYMBOL(fb_io_mmap);
170 
171 MODULE_DESCRIPTION("Fbdev helpers for framebuffers in I/O memory");
172 MODULE_LICENSE("GPL");
173