linux驱动学习（8）----framebuffer子系统LCD屏驱动
主要内容---Framebuffer子系统--LCD屏驱动
1,Framebuffer子系统的框架
2,LCD屏的驱动移植
3, 启动LOGO的制作
4, 应用程序控制LCD屏的方法
5, Framebuffer子系统代码执行的流程
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补充知识点:设定自定义平台数据的方式
1,在pev的初始化的时候给定一个
struct platform_device smdkv210_dm9000 = {
.name = "dm9000",
.id = -1,
.num_resources = ARRAY_SIZE(smdkv210_dm9000_resources),
.resource = smdkv210_dm9000_resources,
.dev = {
.platform_data = &smdkv210_dm9000_platdata,
},
};
2,通过接口随时修改自定义数据
void __init s3c_fb_set_platdata(struct s3c_fb_platdata *pd)// pd就是平台自定义数据
{
struct s3c_fb_platdata *npd;
if (!pd) {
printk(KERN_ERR "%s: no platform data\n", __func__);
return;
}
npd = kmemdup(pd, sizeof(struct s3c_fb_platdata), GFP_KERNEL);
if (!npd)
printk(KERN_ERR "%s: no memory for platform data\n", __func__);
s3c_device_fb.dev.platform_data = npd;
}
1,Framebuffer子系统的框架
应用层
------------------------------------------------
fb通用层:知道映射,但是不知道如何分配显存
1, 负责和用户交互
2, 实现显存的映射
drivers/video/fbmem.c
-------------------------------------------------
drivers/video/s3c-fb.c
lcd控制器层:知道分配显存,但是不知道如何映射
1,初始化lcd控制器
2, 实现显存的分配
2, LCD屏的驱动移植--时序--Documentation/fb/framebuffer.txt
soc lcd屏 驱动
垂直方向
VSPW tvpw 1
LINVAL tvd 480 yres
VFPD tvfp 22 lower_margin
水平方向
HSPW thpw 1
HOZVAL thd 800 xres
HFPD thfp 210 right_margin
pdev:
struct platform_device s3c_device_fb = {
.name = "s3c-fb",
.id = -1,
.num_resources = ARRAY_SIZE(s3c_fb_resource),
.resource = s3c_fb_resource,
.dev.dma_mask = &s3c_device_fb.dev.coherent_dma_mask,
.dev.coherent_dma_mask = 0xffffffffUL,
};
smdkv210_machine_init(void)
|
s3c_fb_set_platdata(&smdkv210_lcd0_pdata);// smdkv210_lcd0_pdata就是自定义数据
1,移植的时候主要是设定自定义数据
arch/arm/mach-s5pv210/mach-smdkv210.c
根据参数修改如下
static struct s3c_fb_pd_win smdkv210_fb_win0 = {
.win_mode = {
.left_margin = 26,
.right_margin = 210,
.upper_margin = 13,
.lower_margin = 22,
.hsync_len = 20,
.vsync_len = 10,
.xres = 800,
.yres = 480,
},
.max_bpp = 32,
.default_bpp = 16, // 和应用有关
};
static struct s3c_fb_platdata smdkv210_lcd0_pdata __initdata = {
.win[0] = &smdkv210_fb_win0,
.vidcon0 = VIDCON0_VIDOUT_RGB | VIDCON0_PNRMODE_RGB,
.vidcon1 = VIDCON1_INV_HSYNC | VIDCON1_INV_VSYNC,
.setup_gpio = s5pv210_fb_gpio_setup_24bpp,
};
2, 确保fb通用层和lcd控制器层的驱动已经存在:
make menuconfig
Device Drivers --->
Graphics support --->
<*> Support for frame buffer devices --->// fbmem.c
<*> Samsung S3C framebuffer support // s3c-fb.c
Console display driver support --->
<*> Framebuffer Console support //将图片加载到显存中去显示
[*] Bootup logo --->
[*] Standard black and white Linux logo (NEW)
[*] Standard 16-color Linux logo (NEW)
[*] Standard 224-color Linux logo (NEW)//表示的是一张图片
3, 开启背光:
smdkv210_machine_init(void)
|
gpio_request(S5PV210_GPD0(0), "gpd0");
gpio_direction_output(S5PV210_GPD0(0),1);
gpio_free(S5PV210_GPD0(0));
make zImage -j2
更新内核:
cp -raf arch/arm/boot/zImage /tftpboot
3, 启动LOGO的制作---为内核添加一个图片,在启动的时候去指定
jpg/bmp------转换成ppm ----> 编译到内核---指定显示你的logo
如果将一个文件编译进内核:
Kconfig
576 config I2C_S3C2410 // CONFIG_I2C_S3C2410
577 tristate "S3C2410 I2C Driver"
578 depends on HAVE_S3C2410_I2C
579 help
580 Say Y here to include support for I2C controller in the
581 Samsung SoCs.
Makefile
obj-$(CONFIG_I2C_S3C2410) += i2c-s3c2410.o
1,制作ppm文件
drivers/video/logo
logo_girl_clut224.ppm
2, 修改Kconfig和Makefile
drivers/video/logo/Kconfig
31 config LOGO_GIRL_CLUT224
32 bool "Linux Girl for test logo"
33 help
34 you can you choose a girl
drivers/video/logo/Makefile
19 obj-$(CONFIG_LOGO_GIRL_CLUT224) += logo_girl_clut224.o
make menuconfig
Device Drivers --->
Graphics support --->
[*] Bootup logo --->
[*] Linux Girl for test logo
make zImage -j2
如果一旦编译成功:logo_girl_clut224.c
const struct linux_logo logo_girl_clut224 __initconst = {
.type = LINUX_LOGO_CLUT224,
.width = 800,
.height = 480,
.clutsize = 224,
.clut = logo_girl_clut224_clut,
.data = logo_girl_clut224_data
};
3, 指定显示你的logo
vim include/linux/linux_logo.h
51 extern const struct linux_logo logo_girl_clut224;
vim drivers/video/logo/logo.c
65 if (depth >= 8) {
66 #ifdef CONFIG_LOGO_LINUX_CLUT224
67 /* Generic Linux logo */
68 logo = &logo_linux_clut224;
69 #endif
//--------------->
72 #ifdef CONFIG_LOGO_GIRL_CLUT224
73 logo = &logo_girl_clut224;
74 #endif
75
make zImage -j2
更新内核:
cp -raf arch/arm/boot/zImage /tftpboot/
---------------------------------------------------------
4, 应用程序控制LCD屏的方法
5, Framebuffer子系统代码执行的流程
fbmem.c
static const struct file_operations fb_fops = {
.owner = THIS_MODULE,
.read = fb_read,
.write = fb_write,
.unlocked_ioctl = fb_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = fb_compat_ioctl,
#endif
.mmap = fb_mmap,
.open = fb_open,
.release = fb_release,
#ifdef HAVE_ARCH_FB_UNMAPPED_AREA
.get_unmapped_area = get_fb_unmapped_area,
#endif
#ifdef CONFIG_FB_DEFERRED_IO
.fsync = fb_deferred_io_fsync,
#endif
.llseek = default_llseek,
};
module_init(fbmem_init);
|
proc_create("fb", 0, NULL, &fb_proc_fops);//在/proc目录下创建了一个fb文件
// 注册主设备号
register_chrdev(FB_MAJOR,"fb",&fb_fops)
//创建类
fb_class = class_create(THIS_MODULE, "graphics");
-------------------------------------------------------------
s3c-fb.c
// fb_info
struct fb_info {
struct fb_var_screeninfo var; //可变参数--主要是时序,bpp
struct fb_fix_screeninfo fix; // 固定参数---显存的信息--一旦分配之后就不会改变
}
struct fb_fix_screeninfo {
unsigned long smem_start; /* Start of frame buffer mem */
/* (physical address) */
__u32 smem_len; /* Length of frame buffer mem */
}
struct fb_var_screeninfo {//可变参数--主要是时序,bpp,会给用户提供接口
__u32 xres; /* visible resolution */
__u32 yres;
__u32 bits_per_pixel; /* guess what */
__u32 pixclock; /* pixel clock in ps (pico seconds) */
__u32 left_margin; /* time from sync to picture */
__u32 right_margin; /* time from picture to sync */
__u32 upper_margin; /* time from sync to picture */
__u32 lower_margin;
__u32 hsync_len; /* length of horizontal sync */
__u32 vsync_len; /* length of vertical sync */
}
pdrv
platform_driver_register(&s3c_fb_driver);
|
s3c_fb_probe(struct platform_device *pdev)
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// 获取自定义数据
pd = pdev->dev.platform_data;
//分配一个全局的设备对象
sfb = kzalloc(sizeof(struct s3c_fb), GFP_KERNEL);
// 时钟使能
sfb->bus_clk = clk_get(dev, "lcd");
clk_enable(sfb->bus_clk);
//地址映射
sfb->regs = ioremap(res->start, resource_size(res));
//中断申请
sfb->irq_no = res->start;
ret = request_irq(sfb->irq_no, s3c_fb_irq,
0, "s3c_fb", sfb);
//初始化gpio口
pd->setup_gpio();
//电平翻转
writel(pd->vidcon1, sfb->regs + VIDCON1);
//在内部中,完成dma显存分配, fb_info初始化以及注册
s3c_fb_probe_win(sfb, win, fbdrv->win[win],&sfb->windows[win]);
|
struct fb_info *fbinfo;
fbinfo = framebuffer_alloc(sizeof(struct s3c_fb_win) + palette_size * sizeof(u32), sfb->dev);
// 初始化
//分配显存
s3c_fb_alloc_memory(sfb, win);
|
fbi->fix.smem_len = size; // xres * yres *max_bpp /8
// dma_alloc_writecombine返回显存的虚拟地址
// map_dma是显存的物理地址
fbi->screen_base = dma_alloc_writecombine(sfb->dev, size,
&map_dma, GFP_KERNEL);
fbi->fix.smem_start = map_dma; //记录到固定参数
fb_videomode_to_var(&fbinfo->var, initmode);
|//将平台自定义数据中的时序值保存到var中
var->xres = mode->xres;
var->yres = mode->yres;
var->xres_virtual = mode->xres;
var->yres_virtual = mode->yres;
var->xoffset = 0;
var->yoffset = 0;
var->pixclock = mode->pixclock;
var->left_margin = mode->left_margin;
var->right_margin = mode->right_margin;
var->upper_margin = mode->upper_margin;
var->lower_margin = mode->lower_margin;
var->hsync_len = mode->hsync_len;
var->vsync_len = mode->vsync_len;
var->sync = mode->sync;
var->vmode = mode->vmode & FB_VMODE_MASK;
fbinfo->fix.type = FB_TYPE_PACKED_PIXELS;
fbinfo->fix.accel = FB_ACCEL_NONE;
fbinfo->var.activate = FB_ACTIVATE_NOW;
fbinfo->var.vmode = FB_VMODE_NONINTERLACED;
fbinfo->var.bits_per_pixel = windata->default_bpp;
fbinfo->fbops = &s3c_fb_ops;
fbinfo->flags = FBINFO_FLAG_DEFAULT;
fbinfo->pseudo_palette = &win->pseudo_palette;
//将时序的值赋值到lcd控制器中去,将dma显存的地址写入到lcd控制器中
s3c_fb_set_par(fbinfo);
|
data = VIDTCON0_VBPD(var->upper_margin - 1) |
VIDTCON0_VFPD(var->lower_margin - 1) |
VIDTCON0_VSPW(var->vsync_len - 1);
writel(data, regs + sfb->variant.vidtcon);
data = VIDTCON1_HBPD(var->left_margin - 1) |
VIDTCON1_HFPD(var->right_margin - 1) |
VIDTCON1_HSPW(var->hsync_len - 1);
/* VIDTCON1 */
writel(data, regs + sfb->variant.vidtcon + 4);
data = VIDTCON2_LINEVAL(var->yres - 1) |
VIDTCON2_HOZVAL(var->xres - 1);
writel(data, regs + sfb->variant.vidtcon + 8);
//将显存的起始位置和结束位置写入到lcd控制器中
writel(info->fix.smem_start, buf + sfb->variant.buf_start);
data = info->fix.smem_start + info->fix.line_length * var->yres;
writel(data, buf + sfb->variant.buf_end);
// 注册
register_framebuffer(fbinfo);
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do_register_framebuffer(fb_info);
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for (i = 0 ; i < FB_MAX; i++)
if (!registered_fb[i])
break;
fb_info->dev = device_create(fb_class, fb_info->device,
MKDEV(FB_MAJOR, i), NULL, "fb%d", i);
registered_fb[i] = fb_info; //将当前注册的fb_info放在数组中
mmap()
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xx_mmap()
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struct fb_info *info = file_fb_info(file); //从数组中得到 fb_info
unsigned long off;
unsigned long start;
// 显存的起始位置
start = info->fix.smem_start;
//假想偏移量为0
off += start;
io_remap_pfn_range(vma, vma->vm_start, off >> PAGE_SHIFT,
vma->vm_end - vma->vm_start, vma->vm_page_prot)
------------------------------------------------------------
4, 应用程序控制LCD屏的方法
1, 打开设备
int fd = open("/dev/fb0", O_RDWR);
2, 获取到lcd屏的信息xres, yres, bpp
struct fb_var_screeninfo var;
ioctl(fd, FBIOGET_VSCREENINFO, &var);
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.unlocked_ioctl = fb_ioctl,
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struct fb_info *info = file_fb_info(file);//
|//从registered_fb数组中得到fb_info
struct fb_info *info = registered_fb[fbidx];
do_fb_ioctl(info, cmd, arg);
|
void __user *argp = (void __user *)arg;
switch (cmd) {
case FBIOGET_VSCREENINFO:
var = info->var;
copy_to_user(argp, &var, sizeof(var)) ? -EFAULT : 0;
size_t length = var.xres * var.yres * var.bits_per_pixel / 8
3,映射显存到用户空间
char *addr = mmap(NULL, size_t length, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
framebuffer_ptr =(char *)mmap( NULL,//如果此值为NULL,则表示用内核来自动给你分配一块虚拟空间
screensize, //空间大小
PROT_READ|PROT_WRITE,//权限
MAP_SHARED, //是否可以共享
framebuffer_fd, //文件描述符
0); //从哪个地方开始
4, 得到图片数据,将数据写入到addr
/*1.打开一副图片*/
pic_fd =open(argv[2],O_RDWR);
printf("pic_fd=%d\n",pic_fd);
/*2.获取图片大小*/
len =lseek(pic_fd, 0, SEEK_END);
printf("len =%ld\n",len);
buffer =(char *)malloc(len);
lseek(pic_fd, 0, SEEK_SET);
/*3.读取图片数据*/
read(pic_fd,buffer,len);
// buffer 存了bmp的图片数据, framebuffer_ptr映射之后的显存位置
draw_bmp(buffer,(unsigned short *) framebuffer_ptr);
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bmp_read_file(bmpfilename, &bmpdata);//跳过bmp文件头
bmp2fb16_rgb565(bmpdata, fb);
|//bmp2fb16_rgb565(unsigned char *bmpdata,unsigned short *fb16)
fb16_buff = fb16; // fb16_buff就是framebuffer_ptr,映射之后的显存位置
for (y = ysize; y > 0 ; y--)
{
for (x = 0 ; x < xsize; x++) /*copy one line to frame buffer*/
{
/*copy one pixel to frame buffer*/
b = *bmpdata;
bmpdata++;
b >>= 3;
g = *bmpdata;
bmpdata++;
g >>= 2;
r = *bmpdata;
bmpdata++;
r >>= 3;
pixel16 = (unsigned short) ((r << 11) | (g << 5) | b);
*( fb16_buff + (y* xsize + x) ) = pixel16;//将一个像素填写到显存
}
}
lcd屏的框架：
其对应的时序图：
