Smart210学习-----lcd驱动

分类: IT文章 • 2022-08-10 11:00:52

帧缓冲设备

1.1帧缓冲设备：
帧缓冲（framebuffer）是 Linux 系统为显示设备提供的一个接口，它将显示缓冲区抽象，屏蔽图像硬件的底层差异，允许上层应用程序在图形模式下直接对显示缓冲区进行读写操作。用户不必关心物理显示缓冲区的具体位置及存放方式，这些都由帧缓冲设备驱动本身来完成。对于帧缓冲设备而言，只要在显示缓冲区中与显示点对应的区域写入颜色值，对应的颜色会自动在屏幕上显示。

1.2 Linux帧缓冲相关数据结构与函数
　　fb_info结构体
　　　　帧缓冲设备最关键的一个数据结构体是fb_info结构体（为了便于记忆，我们把它简称为“FBI”），
　　FBI中包括了关于帧缓冲设备属性和操作的完整描述。

FBI 中记录了帧缓冲设备的全部信息，包括设备的设置参数、状态以及操作函数指针。每一个帧缓冲设备都必须对应一个 FBI。

1  struct fb_info {  
2     int node;  
3     int flags;  
4     struct mutex lock;              /* 用于 open/release/ioctl 的锁 */   
5     struct fb_var_screeninfo var; /*可变参数 */  
6     struct fb_fix_screeninfo fix; /*固定参数 */  
7     struct fb_monspecs monspecs; /*显示器标准 */  
8     struct work_struct queue; /* 帧缓冲事件队列 */  
9     struct fb_pixmap pixmap; /* 图像硬件 mapper */  
10    struct fb_pixmap sprite; /* 光标硬件 mapper */  
11    struct fb_cmap cmap; /* 目前的颜色表*/  
12    struct list_head modelist;   
13    struct fb_videomode *mode; /* 目前的 video 模式 */  
14   
15    #ifdef CONFIG_FB_BACKLIGHT  
16       /* 对应的背光设备 */  
17       struct backlight_device *bl_dev;  
18       /* 背光调整 */  
19       struct mutex bl_mutex;  
20       u8 bl_curve[FB_BACKLIGHT_LEVELS];  
21     #endif  
22     #ifdef CONFIG_FB_DEFERRED_IO  
23         struct delayed_work deferred_work;  
24         struct fb_deferred_io *fbdefio;  
25     #endif  
26     struct fb_ops *fbops; /* fb_ops，帧缓冲操作 */  
27     struct device *device; /* 父设备 */  
28     struct device *dev;             /* fb 设备 */  
29     int class_flag; /* 私有 sysfs 标志 */  
30     #ifdef CONFIG_FB_TILEBLITTING  
31         struct fb_tile_ops *tileops; /* 图块 Blitting */  
32     #endif  
33     char _ _iomem *screen_base; /* 虚拟基地址 */  
34     unsigned long screen_size; /* ioremapped 的虚拟内存大小 */  
35     void *pseudo_palette; /* 伪 16 色颜色表 */  
36     #define FBINFO_STATE_RUNNING 0  
37     #define FBINFO_STATE_SUSPENDED         1  
38     u32 state; /* 硬件状态，如挂起 */  
39     void *fbcon_par;  
40     void *par;  
41 };

fb_info结构体

fb_ops 结构体
FBI 的成员变量 fbops 为指向底层操作的函数的指针，这些函数是需要驱动程序开发人员编
写的。

1  struct fb_ops {  
2      struct module *owner;  
3       /* 打开/释放 */  
4      int(*fb_open)(struct fb_info *info, int user);  
5      int(*fb_release)(struct fb_info *info, int user);  
6    
7      /* 对于非线性布局的/常规内存映射无法工作的帧缓冲设备需要 */  
8      ssize_t(*fb_read)(struct file *file, char _ _user *buf, size_t count,  
9         loff_t*ppos);  
10     ssize_t(*fb_write)(struct file *file, const char _ _user *buf, size_t count,  
11        loff_t *ppos);  
12   
13     /* 检测可变参数，并调整到支持的值*/  
14     int(*fb_check_var)(struct fb_var_screeninfo *var, struct fb_info *info);  
15   
16    /* 根据 info->var 设置 video 模式 */  
17    int(*fb_set_par)(struct fb_info *info);  
18   
19    /* 设置 color 寄存器 */  
20    int(*fb_setcolreg)(unsigned regno, unsigned red, unsigned green, unsigned  
21        blue, unsigned transp, struct fb_info *info);  
22   
23     /* 批量设置 color 寄存器，设置颜色表 */  
24     int(*fb_setcmap)(struct fb_cmap *cmap, struct fb_info *info);  
25   
26     /*显示空白 */  
27     int(*fb_blank)(int blank, struct fb_info *info);  
28   
29     /* pan 显示 */  
30     int(*fb_pan_display)(struct fb_var_screeninfo *var, struct fb_info *info);  
31   
32     /* 矩形填充 */  
33     void(*fb_fillrect)(struct fb_info *info, const struct fb_fillrect *rect);  
34     /* 数据复制 */  
35     void(*fb_copyarea)(struct fb_info *info, const struct fb_copyarea *region);  
36     /* 图形填充 */  
37     void(*fb_imageblit)(struct fb_info *info, const struct fb_image *image);  
38   
39     /* 绘制光标 */  
40     int(*fb_cursor)(struct fb_info *info, struct fb_cursor *cursor);  
41   
42     /* 旋转显示 */  
43     void(*fb_rotate)(struct fb_info *info, int angle);  
44   
45     /* 等待 blit 空闲 (可选) */  
46     int(*fb_sync)(struct fb_info *info);  
47   
48     /* fb 特定的 ioctl (可选) */  
49   int(*fb_ioctl)(struct fb_info *info, unsigned int cmd, unsigned long arg);  
50   
51   /* 处理 32 位的 compat ioctl (可选) */  
52   int(*fb_compat_ioctl)(struct fb_info *info, unsigned cmd, unsigned long arg);  
53   
54   /* fb 特定的 mmap */  
55   int(*fb_mmap)(struct fb_info *info, struct vm_area_struct *vma);  
56   
57   /* 保存目前的硬件状态 */  
58   void(*fb_save_state)(struct fb_info *info);  
59   
60   /* 恢复被保存的硬件状态 */  
61   void(*fb_restore_state)(struct fb_info *info);  
62  
63   void (*fb_get_caps)(struct fb_info *info, struct fb_blit_caps *caps,  
64            struct fb_var_screeninfo *var);  
65 };

fb_ops 结构体

　fb_var_screeninfo 和 fb_fix_screeninfo 结构体

　　　FBI 的 fb_var_screeninfo 和 fb_fix_screeninfo 成员也是结构体，fb_var_screeninfo 记录用户可修改的显示控制器参数，包括屏幕分辨率和每个像素点的比特数。fb_var_screeninfo 中的 xres 定义屏幕一行有多少个点，yres 定义屏幕一列有多少个点，bits_per_pixel 定义每个点用多少个字节表示。而 fb_fix_screeninfo 中记录用户不能修改的显示控制器的参数，如屏幕缓冲区的物理地址、长度。当对帧缓冲设备进行映射操作的时候，就是从 fb_fix_screeninfo 中取得缓冲区物理地址的。上述数据成员都需要在驱动程序中初始化和设置。

1  struct fb_var_screeninfo {  
2     /* 可见解析度 */  
3     u32 xres;  
4     u32 yres;  
5     /* 虚拟解析度  */  
6     u32 xres_virtual;  
7     u32 yres_virtual;  
8     /* 虚拟到可见之间的偏移 */  
9     u32 xoffset;  
10    u32 yoffset;  
11   
12    u32 bits_per_pixel; /* 每像素位数，BPP */  
13    u32 grayscale; /非 0 时指灰度 */  
14   
15    /* fb 缓存的 RGB 位域 */  
16    struct fb_bitfield red;  
17    struct fb_bitfield green;  
18    struct fb_bitfield blue;  
19    struct fb_bitfield transp; /* 透明度 */  
20   
21    u32 nonstd; /* != 0 非标准像素格式 */  
22   
23    u32 activate;  
24   
25    u32 height; /*高度 */  
26    u32 width; /*宽度 */  
27   
28    u32 accel_flags; /* 看 fb_info.flags */  
29   
30    /* 定时: 除了 pixclock 本身外，其他的都以像素时钟为单位 */  
31    u32 pixclock; /* 像素时钟（皮秒） */  
32    u32 left_margin; /* 行切换：从同步到绘图之间的延迟    */  
33    u32 right_margin; /* 行切换：从绘图到同步之间的延迟   */  
34    u32 upper_margin; /* 帧切换：从同步到绘图之间的延迟  */  
35    u32 lower_margin; /* 帧切换：从绘图到同步之间的延迟  */  
36    u32 hsync_len; /* 水平同步的长度     */  
37    u32 vsync_len; /* 垂直同步的长度     */  
38    u32 sync;  
39    u32 vmode;  
40    u32 rotate; /* 顺时钟旋转的角度 */  
41    u32 reserved[5]; /* 保留 */  
42 };

fb_var_screeninfo 结构体

1 struct fb_fix_screeninfo { 2 char id[16]; /* 字符串形式的标识符 */ 3 unsigned long smem_start; /* fb 缓冲内存的开始位置（物理地址） */ 4 u32 smem_len; /* fb 缓冲的长度 */ 5 u32 type; /* FB_TYPE_* */ 6 u32 type_aux; /* Interleave */ 7 u32 visual; /* FB_VISUAL_* */ 8 u16 xpanstep; /* 如果没有硬件 panning ，赋 0 */ 9 u16 ypanstep; 10 u16 ywrapstep;/ 11 u32 line_length; /* 1 行的字节数 */ 12 unsigned long mmio_start; /* 内存映射 I/O 的开始位置 */ 13 u32 mmio_len; /* 内存映射 I/O 的长度 */ 14 u32 accel; 15 u16 reserved[3]; /* 保留*/ 16 };

1 static struct file_operations fb_fops = { 2 .owner = THIS_MODULE, 3 .read = fb_read, 4 .write = fb_write, 5 .ioctl = fb_ioctl, 6 #ifdef CONFIG_COMPAT 7 .compat_ioctl = fb_compat_ioctl, 8 #endif 9 .mmap = fb_mmap, 10 .open = fb_open, 11 .release = fb_release, 12 #ifdef HAVE_ARCH_FB_UNMAPPED_AREA 13 .get_unmapped_area = get_fb_unmapped_area, 14 #endif 15 #ifdef CONFIG_FB_DEFERRED_IO 16 .fsync = fb_deferred_io_fsync, 17 #endif 18 };

1 /* 平台驱动结构体 */ 2 static struct platform_driver xxxfb_driver = { 3 .probe = xxxfb_probe, 4 .remove = xxxfb_remove, 5 .suspend = xxxfb_suspend, 6 .resume = xxxfb_resume, 7 .driver = { 8 .name = "xxx-lcd", /* 驱动名 */ 9 .owner = THIS_MODULE, 10 } 11 }; 12 13 /* 平台驱动探测函数 */ 14 static int _ _init xxxfb_probe(...) 15 { 16 struct fb_info *info; 17 18 /*分配 fb_info 结构体*/ 19 info = framebuffer_alloc(...); 20 21 info->screen_base = framebuffer_virtual_memory; 22 info->var = xxxfb_var; /* 可变参数 */ 23 info->fix = xxxfb_fix; /* 固定参数 */ 24 25 /*分配显示缓冲区*/ 26 alloc_dis_buffer(...); 27 28 /*初始化 LCD 控制器*/ 29 lcd_init(...); 30 31 /*检查可变参数*/ 32 xxxfb_check_var(&info->var, info); 33 34 /*注册 fb_info*/ 35 if (register_framebuffer(info) < 0) 36 return - EINVAL; 37 38 return 0; 39 } 40 41 /* 平台驱动移除函数 */ 42 static void _ _exit xxxfb_remove(...) 43 { 44 struct fb_info *info = dev_get_drv_data(dev); 45 46 if (info) { 47 unregister_framebuffer(info); /* 注销 fb_info */ 48 dealloc_dis_buffer(...); /* 释放显示缓冲区 */ 49 framebuffer_release(info); /* 注销 fb_info */ 50 } 51 52 return 0; 53 } 54 55 /* 帧缓冲设备驱动模块加载与卸载函数 */ 56 int __init xxxfb_init(void) 57 { 58 return platform_driver_register(&xxxfb_driver); /* 注册平台设备 */ 59 } 60 61 static void __exit xxxfb_cleanup(void) 62 { 63 platform_driver_unregister(&xxxfb_driver); /* 注销平台设备 */ 64 } 65 66 module_init(xxxfb_init); 67 module_exit(xxxfb_cleanup);

#include <linux/module.h> #include <linux/kernel.h> #include <linux/errno.h> #include <linux/string.h> #include <linux/mm.h> #include <linux/slab.h> #include <linux/delay.h> #include <linux/fb.h> #include <linux/init.h> #include <linux/dma-mapping.h> #include <linux/interrupt.h> #include <linux/platform_device.h> #include <linux/clk.h> #include <linux/cpufreq.h> #include <asm/io.h> #include <asm/div64.h> #include <asm/mach/map.h> #include <mach/regs-gpio.h> //lcd控制器寄存器 struct lcd_regs { unsigned long VIDCON0; unsigned long VIDCON1; unsigned long VIDCON2; unsigned long VIDCON3; unsigned long VIDTCON0; unsigned long VIDTCON1 ; unsigned long VIDTCON2 ; unsigned long VIDTCON3 ; unsigned long WINCON0 ; unsigned long WINCON1 ; unsigned long WINCON2 ; unsigned long WINCON3 ; unsigned long WINCON4 ; unsigned long SHADOWCON; }; static unsigned long *VIDOSD0A; static unsigned long *VIDOSD0B; static unsigned long *VIDOSD0C; static unsigned long *VIDW00ADD0B0; static unsigned long *VIDW00ADD1B0; static struct lcd_regs *lcd_reg; static unsigned long *DISPLAY_CONTROL; /* LCD参数 */ #define VSPW 9 #define VBPD 13 #define LINEVAL 479 #define VFPD 21 #define HSPW 19 #define HBPD 25 #define HOZVAL 799 #define HFPD 209 #define LINEVAL 479 #define HOZVAL 799 #define LeftTopX_F 0 #define LeftTopY_F 0 #define RightBotX_F 799 #define RightBotY_F 479 /* 用于LCD的GPIO */ static unsigned long *gpf0con; static unsigned long *gpf1con; static unsigned long *gpf2con; static unsigned long *gpf3con; static unsigned long *gpd0con; static unsigned long *gpd0dat; static struct fb_info *lcd_info; static unsigned int pseudo_palette[16]; static inline unsigned int chan_to_field(unsigned int chan, struct fb_bitfield *bf) { chan &= 0xffff; chan >>= 16 - bf->length; return chan << bf->offset; } static int smart210_lcdfb_setcolreg(unsigned regno, unsigned red, unsigned green, unsigned blue, unsigned transp, struct fb_info *info) { unsigned int val; if (regno > 16) return 1; /* 用red,green,blue三原色构造出val */ val = chan_to_field(red, &info->var.red); val |= chan_to_field(green, &info->var.green); val |= chan_to_field(blue, &info->var.blue); //((u32 *)(info->pseudo_palette))[regno] = val; pseudo_palette[regno] = val; return 0; } static struct fb_ops smart210_lcd_ops = { .owner = THIS_MODULE, .fb_setcolreg = smart210_lcdfb_setcolreg, .fb_fillrect = cfb_fillrect, .fb_copyarea = cfb_copyarea, .fb_imageblit = cfb_imageblit, }; static int __init my_lcd_init(void) { struct clk *lcd_clk; /*分配一个fb_info的结构体*/ lcd_info = framebuffer_alloc(0 ,NULL); if(IS_ERR(lcd_info)) { printk(KERN_ALERT"framebuffer_alloc error "); return -ENOMEM; } /*设置*/ /*配置fix固定参数*/ strcpy(lcd_info->fix.id, "Smart210_lcd"); //lcd_info->fix.smem_start lcd_info->fix.smem_len = 800 * 480 * 4; /*7寸屏，rgb 8:8:8*/ lcd_info->fix.type = FB_TYPE_PACKED_PIXELS; lcd_info->fix.visual = FB_VISUAL_TRUECOLOR; //真彩 lcd_info->fix.line_length = 800 * 4; /*配置可变参数var*/ lcd_info->var.xres = 800; lcd_info->var.yres = 480; lcd_info->var.xres_virtual = 800; lcd_info->var.yres_virtual = 480; lcd_info->var.xoffset = 0; lcd_info->var.yoffset = 0; lcd_info->var.bits_per_pixel = 32; //每个像素多少位 32位 lcd_info->var.grayscale = 0; //灰度级设为0 lcd_info->var.red.length = 8; lcd_info->var.red.offset = 16; lcd_info->var.green.length = 8; lcd_info->var.green.offset = 8; lcd_info->var.blue.length = 8; lcd_info->var.blue.offset = 0; lcd_info->var.nonstd = 0; //标准像素 lcd_info->var.activate = FB_ACTIVATE_NOW; /*配置操作函数*/ lcd_info->fbops = &smart210_lcd_ops; //lcd_info->screen_base = ; /*虚拟基地址*/ lcd_info->screen_size = 800 * 480 * 4; lcd_info->pseudo_palette = pseudo_palette; //调色板 /*硬件相关的操作*/ gpf0con = ioremap(0xE0200120, 4); gpf1con = ioremap(0xE0200140, 4); gpf2con = ioremap(0xE0200160, 4); gpf3con = ioremap(0xE0200180, 4); gpd0con = ioremap(0xE02000A0, 4); gpd0dat = ioremap(0xE02000A4, 4); *gpf0con = 0x22222222; *gpf1con = 0x22222222; *gpf2con = 0x22222222; *gpf3con = 0x22222222; *gpd0con |= 1<<4; *gpd0dat |= 1<<1; lcd_clk = clk_get(NULL, "lcd"); if(IS_ERR(lcd_clk)) { printk(KERN_ALERT"clk_get error "); return -EINVAL; } clk_enable(lcd_clk); DISPLAY_CONTROL = ioremap( 0xE0107008, 4); lcd_reg = ioremap(0xF8000000, sizeof(struct lcd_regs)); VIDOSD0A = ioremap(0xF8000040, 4); VIDOSD0B = ioremap(0xF8000044, 4); VIDOSD0C = ioremap(0xF8000048, 4); VIDW00ADD0B0 = ioremap(0xF80000A0 , 4); VIDW00ADD1B0 = ioremap(0xF80000D0 , 4); *DISPLAY_CONTROL |= (2 << 0); //显示路径，必须 /* *vidcon0[28:26] 000 = WB interface and RGB interface *vidcon0[18] 0 *vidcon0[13:6] 0x4 5分频 *vidcon0[4] 1 = Divided by CLKVAL_F *vidcon0[2] 0 = HCLK 166.75 MHz *vidcon0[1]:ENVID 0 = Disables the video output and display control signal *vidcon0[0]:ENVID_F 0 = Disables the video output and display control signal. *NOTE: Display On: ENVID and ENVID_F are set to “1”. Direct Off: ENVID and ENVID_F are set to “0” simultaneously. Per Frame Off: ENVID_F is set to “0” and ENVID is set to “1”. */ lcd_reg->VIDCON0 &= ~((7 << 26) | (1 << 18) | (0xff << 6) | (1 << 2)); lcd_reg->VIDCON0 |= (0x4 << 6) | (1 << 4); /* *vidcon1[6] IHSYNC 1 = 反转根据芯片手册和lcd手册 *vidcon1[5] IVSYNC 1 = 反转 */ lcd_reg->VIDCON1 &= ~(1<<7); /* 在vclk的下降沿获取数据 */ lcd_reg->VIDCON1 |= (1 << 6) | (1 << 5); /* 设置时序(需要修改) */ lcd_reg->VIDTCON0 = (VBPD << 16) | (VFPD << 8) | (VSPW << 0); lcd_reg->VIDTCON1 = (HBPD << 16) | (HFPD << 8) | (HSPW << 0); /*设置水平大小，垂直大小*/ lcd_reg->VIDTCON2 |= LINEVAL << 11; lcd_reg->VIDTCON2 |= HOZVAL << 0; /* *WSWP_F [15] :1 = Swap Enable(为什么要使能)，，能够解决掉重影问题 *BPPMODE_F [5:2] 0xb = 24bpp *ENWIN_F [0] 1 Enables/ disables video output and logic immediately. */ lcd_reg->WINCON0 |= 1 << 15; lcd_reg->WINCON0 &= ~(0xf << 2); lcd_reg->WINCON0 |= 0xb << 2 | 1 << 0; /*窗口0 指定左上方,右下方像素的水平屏幕坐标*/ *VIDOSD0A |= (LeftTopX_F << 11) | (LeftTopY_F << 0); *VIDOSD0B |= (RightBotX_F << 11) | (RightBotX_F << 0); *VIDOSD0C |= ((LINEVAL + 1) * (HOZVAL + 1)); /*分配显存*/ lcd_info->screen_base = dma_alloc_writecombine(NULL, lcd_info->fix.smem_len, (dma_addr_t *)&(lcd_info->fix.smem_start), GFP_KERNEL); *VIDW00ADD0B0 = lcd_info->fix.smem_start; //显存的起始地址 *VIDW00ADD1B0 = lcd_info->fix.smem_start + lcd_info->fix.smem_len;//显存的结束地址 lcd_reg->SHADOWCON |= 0x1; //我们使用的是 Window0，所有需要使能 DMA 通道 0 /* LCD控制器开启 */ lcd_reg->VIDCON0 |= 0x3; lcd_reg->WINCON0 |= 0x1; /*注册*/ register_framebuffer(lcd_info); return 0; } static void __exit my_lcd_exit(void) { unregister_framebuffer(lcd_info); dma_free_writecombine(NULL, lcd_info->fix.smem_len, &(lcd_info->fix.smem_start), GFP_KERNEL); iounmap(gpf0con); iounmap(gpf1con); iounmap(gpf2con); iounmap(gpf3con); iounmap(gpd0con); iounmap(gpd0dat); iounmap(lcd_reg); iounmap(VIDOSD0A); iounmap(VIDOSD0B); iounmap(VIDOSD0C); iounmap(VIDW00ADD0B0); iounmap(VIDW00ADD1B0); framebuffer_release(lcd_info); } MODULE_LICENSE("GPL"); module_init(my_lcd_init); module_exit(my_lcd_exit);

Smart210学习-----lcd驱动

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