fb_io_fops.c

  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");