/*
* Copyright 2004-2011 Freescale Semiconductor, Inc. All Rights Reserved.
*/
/*
* The code contained herein is licensed under the GNU General Public
* License. You may obtain a copy of the GNU General Public License
* Version 2 or later at the following locations:
*
* http://www.opensource.org/licenses/gpl-license.html
* http://www.gnu.org/copyleft/gpl.html
*/
/*!
* @defgroup Framebuffer Framebuffer Driver for surface sharing.
*/
/*!
* @file virtual_fb.c
*
* @brief Virtual Frame buffer driver for surface sharing
*
* @ingroup Framebuffer
*/
/*!
* Include files
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <linux/fb.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/ioport.h>
#include <linux/dma-mapping.h>
#include <linux/clk.h>
#include <linux/console.h>
#include <linux/io.h>
#include <linux/uaccess.h>
#include <asm/mach-types.h>
/*
* Driver name
*/
#define VIRT_FB_NAME "virtual_fb"
static int vfbcount = 10;
module_param(vfbcount, int, 0);
static struct fb_info ** g_fb_list;
static int virtfb_map_video_memory(struct fb_info *fbi);
static int virtfb_unmap_video_memory(struct fb_info *fbi);
/*
* Set fixed framebuffer parameters based on variable settings.
*
* @param info framebuffer information pointer
*/
static int virtfb_set_fix(struct fb_info *info)
{
struct fb_fix_screeninfo *fix = &info->fix;
struct fb_var_screeninfo *var = &info->var;
fix->line_length = var->xres_virtual * var->bits_per_pixel / 8;
fix->type = FB_TYPE_PACKED_PIXELS;
fix->accel = FB_ACCEL_NONE;
fix->visual = FB_VISUAL_TRUECOLOR;
fix->xpanstep = 1;
fix->ywrapstep = 1;
fix->ypanstep = 1;
return 0;
}
/*
* Set framebuffer parameters and change the operating mode.
*
* @param info framebuffer information pointer
*/
static int virtfb_set_par(struct fb_info *fbi)
{
int retval = 0;
u32 mem_len;
dev_dbg(fbi->device, "Reconfiguring framebuffer\n");
virtfb_set_fix(fbi);
mem_len = fbi->var.yres_virtual * fbi->fix.line_length;
if (!fbi->fix.smem_start || (mem_len > fbi->fix.smem_len)) {
if (fbi->fix.smem_start)
virtfb_unmap_video_memory(fbi);
if (virtfb_map_video_memory(fbi) < 0)
return -ENOMEM;
}
return retval;
}
/*
* Check framebuffer variable parameters and adjust to valid values.
*
* @param var framebuffer variable parameters
*
* @param info framebuffer information pointer
*/
static int virtfb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
{
/* fg should not bigger than bg */
if (var->xres_virtual < var->xres)
var->xres_virtual = var->xres;
if (var->yres_virtual < var->yres)
var->yres_virtual = var->yres;
if ((var->bits_per_pixel != 32) && (var->bits_per_pixel != 24) &&
(var->bits_per_pixel != 16) && (var->bits_per_pixel != 12) &&
(var->bits_per_pixel != 8))
var->bits_per_pixel = 16;
switch (var->bits_per_pixel) {
case 8:
var->red.length = 3;
var->red.offset = 5;
var->red.msb_right = 0;
var->green.length = 3;
var->green.offset = 2;
var->green.msb_right = 0;
var->blue.length = 2;
var->blue.offset = 0;
var->blue.msb_right = 0;
var->transp.length = 0;
var->transp.offset = 0;
var->transp.msb_right = 0;
break;
case 16:
var->red.length = 5;
var->red.offset = 11;
var->red.msb_right = 0;
var->green.length = 6;
var->green.offset = 5;
var->green.msb_right = 0;
var->blue.length = 5;
var->blue.offset = 0;
var->blue.msb_right = 0;
var->transp.length = 0;
var->transp.offset = 0;
var->transp.msb_right = 0;
break;
case 24:
var->red.length = 8;
var->red.offset = 16;
var->red.msb_right = 0;
var->green.length = 8;
var->green.offset = 8;
var->green.msb_right = 0;
var->blue.length = 8;
var->blue.offset = 0;
var->blue.msb_right = 0;
var->transp.length = 0;
var->transp.offset = 0;
var->transp.msb_right = 0;
break;
case 32:
var->red.length = 8;
var->red.offset = 16;
var->red.msb_right = 0;
var->green.length = 8;
var->green.offset = 8;
var->green.msb_right = 0;
var->blue.length = 8;
var->blue.offset = 0;
var->blue.msb_right = 0;
var->transp.length = 8;
var->transp.offset = 24;
var->transp.msb_right = 0;
break;
}
var->height = -1;
var->width = -1;
var->grayscale = 0;
return 0;
}
/*
* Pan or Wrap the Display
*
* This call looks only at xoffset, yoffset and the FB_VMODE_YWRAP flag
*
* @param var Variable screen buffer information
* @param info Framebuffer information pointer
*/
static int
virtfb_pan_display(struct fb_var_screeninfo *var, struct fb_info *info)
{
if (info->var.yoffset == var->yoffset)
return 0; /* No change, do nothing */
if ((var->yoffset + info->var.yres) > info->var.yres_virtual)
return -EINVAL;
info->var.yoffset = var->yoffset;
return 0;
}
/*
* Function to handle custom mmap for virtual framebuffer.
*
* @param fbi framebuffer information pointer
*
* @param vma Pointer to vm_area_struct
*/
static int virtfb_mmap(struct fb_info *fbi, struct vm_area_struct *vma)
{
u32 len;
unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
if (offset < fbi->fix.smem_len) {
/* mapping framebuffer memory */
len = fbi->fix.smem_len - offset;
vma->vm_pgoff = (fbi->fix.smem_start + offset) >> PAGE_SHIFT;
} else {
return -EINVAL;
}
len = PAGE_ALIGN(len);
if (vma->vm_end - vma->vm_start > len)
return -EINVAL;
/* make buffers bufferable */
vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
vma->vm_flags |= VM_IO | VM_RESERVED;
if (remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
vma->vm_end - vma->vm_start, vma->vm_page_prot)) {
dev_dbg(fbi->device, "mmap remap_pfn_range failed\n");
return -ENOBUFS;
}
return 0;
}
/*!
* This structure contains the pointers to the control functions that are
* invoked by the core framebuffer driver to perform operations like
* blitting, rectangle filling, copy regions and cursor definition.
*/
static struct fb_ops virtfb_ops = {
.owner = THIS_MODULE,
.fb_set_par = virtfb_set_par,
.fb_check_var = virtfb_check_var,
.fb_pan_display = virtfb_pan_display,
.fb_mmap = virtfb_mmap,
};
/*
* Main framebuffer functions
*/
/*!
* Allocates the DRAM memory for the frame buffer. This buffer is remapped
* into a non-cached, non-buffered, memory region to allow palette and pixel
* writes to occur without flushing the cache. Once this area is remapped,
* all virtual memory access to the video memory should occur at the new region.
*
* @param fbi framebuffer information pointer
*
* @return Error code indicating success or failure
*/
static int virtfb_map_video_memory(struct fb_info *fbi)
{
if (fbi->fix.smem_len < fbi->var.yres_virtual * fbi->fix.line_length)
fbi->fix.smem_len = fbi->var.yres_virtual *
fbi->fix.line_length;
fbi->screen_base = dma_alloc_writecombine(fbi->device,
fbi->fix.smem_len,
(dma_addr_t *)&fbi->fix.smem_start,
GFP_DMA);
if (fbi->screen_base == 0) {
dev_err(fbi->device, "Unable to allocate framebuffer memory\n");
fbi->fix.smem_len = 0;
fbi->fix.smem_start = 0;
return -EBUSY;
}
dev_dbg(fbi->device, "allocated fb @ paddr=0x%08X, size=%d.\n",
(uint32_t) fbi->fix.smem_start, fbi->fix.smem_len);
fbi->screen_size = fbi->fix.smem_len;
/* Clear the screen */
memset((char *)fbi->screen_base, 0, fbi->fix.smem_len);
return 0;
}
/*!
* De-allocates the DRAM memory for the frame buffer.
*
* @param fbi framebuffer information pointer
*
* @return Error code indicating success or failure
*/
static int virtfb_unmap_video_memory(struct fb_info *fbi)
{
dma_free_writecombine(fbi->device, fbi->fix.smem_len,
fbi->screen_base, fbi->fix.smem_start);
fbi->screen_base = 0;
fb
基于imx6q 的virtual framebuffer 官方例子
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2018-07-21
13:14:17
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259-virt_fb.tgz （9个子文件） 
virt_fb 
.virtual_fb.o.cmd 189KB .virtual_fb.mod.o.cmd 18KB .virtual_fb.c.swp 80KB .built-in.o.cmd 228B virtual_fb.c 11KB README 606B .tmp_versions virtual_fb.mod 69B .virtual_fb.ko.cmd 345B Makefile 23B资源评论
