TQ2440(S3C2440)移植Linux-4.0.1内核全过程

古城微笑少年丶 2023-07-25 09:57 7阅读 0赞

# TQ2440(S3C2440)移植Linux-4.0.1内核全过程 #

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**文件系统yaffs2下载地址：[https://yaffs.net/get-yaffs][https_yaffs.net_get-yaffs]**  
**linux内核下载地址：[https://mirror.bjtu.edu.cn/kernel/linux/kernel/][https_mirror.bjtu.edu.cn_kernel_linux_kernel]**

--------------------

**构建根文件系统在这里：[嵌入式Linux构建yaffs根文件系统][Linux_yaffs]**

--------------------

## （一）初步移植启动linux内核 ##

**解压linux内核源码：**

tar xvf linux-4.0.1.tar.xz

**获取yaffs2文件系统源码并向linux内核打包使内核支持yaffs2文件系统：**

git clone git://www.aleph1.co.uk/yaffs2
    cd yaffs2
    ./patch-ker.sh c m ../linux-4.0.1

**进入linux内核源码目录并修改顶层Makefile：**

cd ../linux-4.0.1
    gedit Makefile

**找到：**

ARCH        ?= $(SUBARCH)
    CROSS_COMPILE   ?= $(CONFIG_CROSS_COMPILE:"%"=%)

**改为：**

ARCH        ?= arm
    CROSS_COMPILE   ?= arm-linux-

**加载mini2440的配置项：**

make mini2440_defconfig

**打开图形化配置内核：**

make menuconfig

**相关配置如下：**

Device Drivers  --->
     	Input device support  --->
     		[*]   Touchscreens  --->
     			<*>   Samsung S3C2410/generic touchscreen input driver  # 开启触摸屏支持
     	[*] Watchdog Timer Support  --->
     		< >   S3C2410 Watchdog  # 关闭看门狗，要不然系统会一直重启
     	 Graphics support  --->
     	 	[*] Bootup logo  --->
     	 		 [*]   Standard 16-color Linux logo  # 选中该项，取消其他项
     	<*> Memory Technology Device (MTD) support  --->
     		 < >   FTL (Flash Translation Layer) support  # 取消选中，要不然会出现警告：ftl_cs: FTL header not found
     		 < >   NFTL (NAND Flash Translation Layer) support # 取消选中，要不然会出现警告：ftl_cs: 
     		 < >   INFTL (Inverse NAND Flash Translation Layer) support # 取消选中，要不然会出现警告：ftl_cs: 
     		 <*>   NAND Device Support  --->
     		 	<*>   NAND Flash support for Samsung S3C SoCs
     		 		[*]     Samsung S3C NAND Hardware ECC  # 开启NAND的硬件ECC校验
     File systems  ---> 
     	[*] Miscellaneous filesystems  --->
     		<*>   yaffs2 file system support  # 开启yaffs2文件系统支持

**注：开启NAND的硬件ECC校验是选做，如果不开启那么默认使用软件ECC，也可以手动修改文件`drivers/mtd/nand/s3c2410.c`中的`s3c2410_nand_init_chip`函数，将图片框出的一行的宏改为`NAND_ECC_NONE`，即不适用ECC功能：**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxMTUzNDcxNTAz_size_16_color_FFFFFF_t_70]

**修改mini2440的机器码：**

gedit arch/arm/tools/mach-types

**找到：**

mini2440		MACH_MINI2440		MINI2440		1999

**改为：**

mini2440		MACH_MINI2440		MINI2440		168

*168是我的u-boot里的，这个机器码需要跟u-boot中的机器码相对应，要不然u-boot无法引导启动内核，如果你不知道uboot中的机器码是多少，在uboot命令行中输入命令`bdinfo`查看：*  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxMTUzNDcxNTAz_size_16_color_FFFFFF_t_70 1]

**进行初次编译：**

make -j4

*说明：参数4表示4个核心，是CPU的核数，目的为了加快编译速度。*

**出错：`fs/yaffs2/yaffs_vfs.c:321: error: 'struct file' has no member named 'f_dentry'`**  
*看错误信息是说结构体file没有名为f\_dentry的成员，我们查看一下`fs/yaffs2/yaffs_vfs.c`这个文件，定位到第321行是这么一句`obj = yaffs_dentry_to_obj(Y_GET_DENTRY(f));`，也就是说出错的是这个宏Y\_GET\_DENTRY，我们在定位到这个宏的定义位置：*\*

#if (LINUX_VERSION_CODE >= KERNEL_VERSION(4, 4, 0))
    #define PAGE_CACHE_SIZE PAGE_SIZE
    #define PAGE_CACHE_SHIFT PAGE_SHIFT
    #define Y_GET_DENTRY(f) ((f)->f_path.dentry)
    #define YAFFS_NEW_XATTR 1
    #define YAFFS_NEW_GET_LINK 1
    #else
    #define Y_GET_DENTRY(f) ((f)->f_dentry)
    #define YAFFS_NEW_XATTR 0
    #define YAFFS_NEW_GET_LINK 0
    #endif

*这里根据linux的版本宏定义了Y\_GET\_DENTRY，如果linux版本低于4.4那么使用f->f\_dentry，否则使用f->f\_path.dentry，执行的出错的原因是找不到f\_dentry，现在就要去看一下linux-4.0.1内核中的`struct fle`结构体的成员中有关键字dentry的是什么，因为这是文件系统相关的，所以我们到`include/linux/fs.h`中去找：*

struct file { 
    	union { 
    		struct llist_node	fu_llist;
    		struct rcu_head 	fu_rcuhead;
    	} f_u;
    	struct path		f_path;
    	struct inode		*f_inode;	/* cached value */
    	const struct file_operations	*f_op;
    
    	/* * Protects f_ep_links, f_flags. * Must not be taken from IRQ context. */
    	spinlock_t		f_lock;
    	atomic_long_t		f_count;
    	unsigned int 		f_flags;
    	fmode_t			f_mode;
    	struct mutex		f_pos_lock;
    	loff_t			f_pos;
    	struct fown_struct	f_owner;
    	const struct cred	*f_cred;
    	struct file_ra_state	f_ra;
    
    	u64			f_version;
    #ifdef CONFIG_SECURITY
    	void			*f_security;
    #endif
    	/* needed for tty driver, and maybe others */
    	void			*private_data;
    
    #ifdef CONFIG_EPOLL
    	/* Used by fs/eventpoll.c to link all the hooks to this file */
    	struct list_head	f_ep_links;
    	struct list_head	f_tfile_llink;
    #endif /* #ifdef CONFIG_EPOLL */
    	struct address_space	*f_mapping;
    } __attribute__((aligned(4)));	/* lest something weird decides that 2 is OK */
    
    struct file_handle { 
    	__u32 handle_bytes;
    	int handle_type;
    	/* file identifier */
    	unsigned char f_handle[0];
    };

**没有发现dentry的字样，但是看到了`struct path f_path;`，再去这个结构体中看看：**

struct path { 
    	struct vfsmount *mnt;
    	struct dentry *dentry;
    };

**果然找到了dentry成员！那么就将文件fs/yaffs2/yaffs\_vfs.c中的宏：**

#define Y_GET_DENTRY(f) ((f)->f_dentry)

**改为：**

#define Y_GET_DENTRY(f) ((f)->f_path.dentry)

**重新make一下，编译顺利通过！**

**接下来编译出用于u-boot引导的内核镜像：**

make uImage

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxMTUzNDcxNTAz_size_16_color_FFFFFF_t_70 2]  
**成功！**

**下面开始修改内核代码：**

gedit arch/arm/mach-s3c24xx/mach-mini2440.c

**修改NAND默认分区表为：**

/* NAND Flash on MINI2440 board */
    
    static struct mtd_partition mini2440_default_nand_part[] __initdata = { 
    	[0] = { 
    		.name	= "u-boot-spl",
    		.size	= SZ_128K,
    		.offset	= 0,
    	},
    	[1] = { 
    		.name	= "u-boot",
    		.offset = SZ_128K,
    		.size	= SZ_1M - SZ_128K,
    	},
    	[2] = { 
    		.name	= "u-boot-env",
    		.offset = SZ_1M,
    		.size	= SZ_256K,
    	},
    	[3] = { 
    		.name	= "kernel",
    		.offset	= SZ_1M + SZ_256K,
    		.size	= SZ_4M,
    	},
    	[4] = { 
    		.name	= "yaffs2",
    		.offset = SZ_4M + SZ_1M + SZ_256K,
    		.size	= MTDPART_SIZ_FULL,
    	},
    };

--------------------

**下面运行内核进行测试一下，这里我提前做好了yaffs2文件系统（制作方法见本博客首部链接），启动内核后开发板使用nfs的方式挂载文件系统。**

**首先设置uboot启动参数为：**

setenv bootargs noinitrd console=ttySAC0,115200 rootfstype=yaffs2 init=/linuxrc root=/dev/nfs rw nfsroot=192.168.166.254:/opt/embeded/yaffs2 ip=192.168.166.253:192.168.166.254:192.168.166.1:255.255.255.0::eth0:off

**保存环境变量并重启：**

saveenv
    reset

*参数说明：*

*  `nfsroot=192.168.166.254:/opt/embeded/yaffs2`：这是ubuntu的IP地址以及制作的yaffs2文件系统的目录
 *  `ip=192.168.166.253:192.168.166.254:192.168.166.1:255.255.255.0::eth0:off`：ip=\[开发板IP地址\]:\[ubuntu的IP地址\]:\[网关\]:\[掩码\]:eth0:off

**使用tftp下载系统内核镜像并启动：**

tftp 0x32000000 uImage; bootm 0x32000000

**成功启动：**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxMTUzNDcxNTAz_size_16_color_FFFFFF_t_70_pic_center]

**但是通过nfs挂载不上根文件系统，出现了问题：**

*  `nfs: server 192.168.166.254 not responding, still trying`
 *  `mount: server 192.168.166.254 not responding, timed out`

**原因：BWSCON和BANKCON4寄存器关于网卡的配置项有问题。**

**修改代码：**

gedit arch/arm/mach-s3c24xx/mach-mini2440.c

**添加头文件：**

#include "regs-mem.h"
    #include <linux/platform_data/touchscreen-s3c2410.h>

**定位到`mini2440_init`函数，在该函数尾部添加以下代码：**

/* 清除bank4的总线宽度设置 */
        *((volatile unsigned int *)S3C2410_BWSCON) &= ~(3 << 16);
    
    	/* 设置BANK4的总线宽度为16bits、设置开启BANK4等待状态、设置SRAM使用BANK4的UB/LB */
    	*((volatile unsigned int *)S3C2410_BWSCON) |= (1 << 16) | (1 << 18) | (1 << 19);
    
    	/* 设置BANK4控制寄存器 */
    	*((volatile unsigned int *)S3C2410_BANKCON4) = 0X1F7C;

**重新编译后使用tftp下载内核并运行：**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxMTUzNDcxNTAz_size_16_color_FFFFFF_t_70 3]  
**成功挂载！**

## （二）驱动修改 ##

**TQ2440板载一个AT24C02，接在I2C0上。**

gedit arch/arm/mach-s3c24xx/mach-mini2440.c

**找到I2C设备的相关配置，替换为：**

/* * I2C devices */
    static struct at24_platform_data at24c02 = { 
    	.byte_len	= SZ_2K / 8,   /* 2Kbits / 8 = 256bytes */
    	.page_size	= 8,           /* at24c02 page size = 8 */
    	.flags = 0,
    };
    
    static struct i2c_board_info mini2440_i2c_devs[] __initdata = { 
    	{ 
    	    /* * at24c02的地址由8位组成，高四位固定为1010，低四位为A2A1A0R/W, * A2A1A0三个引脚一般拉低与高四位组成7bit的地址码，R/W位为读写控制位， * 为0时表示芯片写操作，组合起来的地址就是0xA0(写)和0xA1(读)， * 但是在Linux系统中I2C设备地址的最高位为1，而剩余7位地址就是去掉R/W位后的剩余7位， * 所以就是0x50。 */
    		I2C_BOARD_INFO("24c02", 0x50),
    		.platform_data = &at24c02,
    	},
    };

**TQ2440板载4个LED灯，位于GPB5-GPB8，找到LED设备的相关配置，替换为：**

/* LEDS */
    
    static struct s3c24xx_led_platdata mini2440_led1_pdata = { 
    	.name		= "led1",
    	.gpio		= S3C2410_GPB(5),
    	.flags		= S3C24XX_LEDF_ACTLOW | S3C24XX_LEDF_TRISTATE,
    	.def_trigger	= "heartbeat",
    };
    
    static struct s3c24xx_led_platdata mini2440_led2_pdata = { 
    	.name		= "led2",
    	.gpio		= S3C2410_GPB(6),
    	.flags		= S3C24XX_LEDF_ACTLOW | S3C24XX_LEDF_TRISTATE,
    	.def_trigger	= "nand-disk",
    };
    
    static struct s3c24xx_led_platdata mini2440_led3_pdata = { 
    	.name		= "led3",
    	.gpio		= S3C2410_GPB(7),
    	.flags		= S3C24XX_LEDF_ACTLOW | S3C24XX_LEDF_TRISTATE,
    	.def_trigger	= "mmc0",
    };
    
    static struct s3c24xx_led_platdata mini2440_led4_pdata = { 
    	.name		= "led4",
    	.gpio		= S3C2410_GPB(8),
    	.flags		= S3C24XX_LEDF_ACTLOW | S3C24XX_LEDF_TRISTATE,
    	.def_trigger	= "",
    };
    
    static struct platform_device mini2440_led1 = { 
    	.name		= "s3c24xx_led",
    	.id		= 1,
    	.dev		= { 
    		.platform_data	= &mini2440_led1_pdata,
    	},
    };
    
    static struct platform_device mini2440_led2 = { 
    	.name		= "s3c24xx_led",
    	.id		= 2,
    	.dev		= { 
    		.platform_data	= &mini2440_led2_pdata,
    	},
    };
    
    static struct platform_device mini2440_led3 = { 
    	.name		= "s3c24xx_led",
    	.id		= 3,
    	.dev		= { 
    		.platform_data	= &mini2440_led3_pdata,
    	},
    };
    
    static struct platform_device mini2440_led4 = { 
    	.name		= "s3c24xx_led",
    	.id		= 4,
    	.dev		= { 
    		.platform_data	= &mini2440_led4_pdata,
    	},
    };

**并删除这两个结构，这两个结构数据未使用，编译的时候会出现警告，当然不删除也不影响：**

static struct platform_device mini2440_led_backlight = { 
    	.name		= "s3c24xx_led",
    	.id		= 5,
    	.dev		= { 
    		.platform_data	= &mini2440_led_backlight_pdata,
    	},
    };
    
    static struct s3c24xx_led_platdata mini2440_led_backlight_pdata = { 
    	.name		= "backlight",
    	.gpio		= S3C2410_GPG(4),
    	.def_trigger	= "backlight",
    };

**修改LCD设备驱动（我的屏幕是W43），找到`_LCD_DECLARE`这个宏并删除，修改`mini2440_lcd_cfg`这个结构为：**

/* LCD timing and setup */
    
    static struct s3c2410fb_display mini2440_lcd_cfg[] __initdata = { 
    
        [0] = { 
    		.lcdcon5	= S3C2410_LCDCON5_FRM565 |
    				  S3C2410_LCDCON5_INVVLINE |
    				  S3C2410_LCDCON5_INVVFRAME |
    				  S3C2410_LCDCON5_PWREN |
    				  S3C2410_LCDCON5_HWSWP,
    
    		.type		= S3C2410_LCDCON1_TFT,
    		.width		= 480,
    		.height		= 272,
    		.pixclock	= 40000, /* HCLK 60 MHz, divisor 10 */
    		.xres		= 480,
    		.yres		= 272,
    		.bpp		= 16,
    		.left_margin	= 19,
    		.right_margin	= 10,
    		.hsync_len	= 30,
    		.upper_margin	= 4,
    		.lower_margin	= 2,
    		.vsync_len	= 8,
        },
    };

**TQ2440板载一个蜂鸣器，接在了GPB0上，这里我们将beep以led平台设备驱动的方式进行注册，添加代码：**

/* BEEP */
    
    static struct s3c24xx_led_platdata mini2440_beep_pdata = { 
    	.name		= "beep",
    	.gpio		= S3C2410_GPB(0),
    	.flags		= S3C24XX_LEDF_TRISTATE,
    };
    
    static struct platform_device mini2440_beep = { 
    	.name		= "s3c24xx_led",
    	.id		= 5,
    	.dev		= { 
    		.platform_data	= &mini2440_beep_pdata,
    	},
    };

**TQ2440板载4个按键，位于GPF0、1、2、4，将按键相关配置改为：**

/* KEYS */
    
    static struct gpio_keys_button mini2440_buttons[] = { 
    	{ 
    		.gpio		= S3C2410_GPF(1),
    		.code		= KEY_UP,
    		.desc		= "Button Up",
    		.active_low	= 0,
    	},
    	{ 
    		.gpio		= S3C2410_GPF(4),
    		.code		= KEY_DOWN,
    		.desc		= "Button Down",
    		.active_low	= 0,
    	},
    	{ 
    		.gpio		= S3C2410_GPF(2),
    		.code		= KEY_LEFT,
    		.desc		= "Button Left",
    		.active_low	= 0,
    	},
    	{ 
    		.gpio		= S3C2410_GPF(0),
    		.code		= KEY_RIGHT,
    		.desc		= "Button Right",
    		.active_low	= 0,
    	},
    };

**修改触摸屏驱动，添加这个结构：**

/* Tcouch Screen */
    
    static struct s3c2410_ts_mach_info mini2440_ts_info __initdata = { 
        .delay = 10000,
    	.presc = 49,
    	.oversampling_shift = 2,
    };

**删除：**

/* * mini2440_features string * * t = Touchscreen present * b = backlight control * c = camera [TODO] * 0-9 LCD configuration * */
    static char mini2440_features_str[12] __initdata = "0tb";
    
    static int __init mini2440_features_setup(char *str)
    { 
    	if (str)
    		strlcpy(mini2440_features_str, str, sizeof(mini2440_features_str));
    	return 1;
    }
    
    __setup("mini2440=", mini2440_features_setup);
    
    #define FEATURE_SCREEN (1 << 0)
    #define FEATURE_BACKLIGHT (1 << 1)
    #define FEATURE_TOUCH (1 << 2)
    #define FEATURE_CAMERA (1 << 3)
    
    struct mini2440_features_t { 
    	int count;
    	int done;
    	int lcd_index;
    	struct platform_device *optional[8];
    };
    
    static void __init mini2440_parse_features(
    		struct mini2440_features_t * features,
    		const char * features_str )
    { 
    	const char * fp = features_str;
    
    	features->count = 0;
    	features->done = 0;
    	features->lcd_index = -1;
    
    	while (*fp) { 
    		char f = *fp++;
    
    		switch (f) { 
    		case '0'...'9':	/* tft screen */
    			if (features->done & FEATURE_SCREEN) { 
    				printk(KERN_INFO "MINI2440: '%c' ignored, "
    					"screen type already set\n", f);
    			} else { 
    				int li = f - '0';
    				if (li >= ARRAY_SIZE(mini2440_lcd_cfg))
    					printk(KERN_INFO "MINI2440: "
    						"'%c' out of range LCD mode\n", f);
    				else { 
    					features->optional[features->count++] =
    							&s3c_device_lcd;
    					features->lcd_index = li;
    				}
    			}
    			features->done |= FEATURE_SCREEN;
    			break;
    		case 'b':
    			if (features->done & FEATURE_BACKLIGHT)
    				printk(KERN_INFO "MINI2440: '%c' ignored, "
    					"backlight already set\n", f);
    			else { 
    				features->optional[features->count++] =
    						&mini2440_led_backlight;
    			}
    			features->done |= FEATURE_BACKLIGHT;
    			break;
    		case 't':
    			printk(KERN_INFO "MINI2440: '%c' ignored, "
    				"touchscreen not compiled in\n", f);
    			break;
    		case 'c':
    			if (features->done & FEATURE_CAMERA)
    				printk(KERN_INFO "MINI2440: '%c' ignored, "
    					"camera already registered\n", f);
    			else
    				features->optional[features->count++] =
    					&s3c_device_camif;
    			features->done |= FEATURE_CAMERA;
    			break;
    		}
    	}
    }

**找到`mini2440_init`函数，删除以下部分：**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxMTUzNDcxNTAz_size_16_color_FFFFFF_t_70_pic_center 1]  
**在for循环下添加设置触摸屏和显示的平台数据：**

s3c24xx_fb_set_platdata(&mini2440_fb_info);
    	s3c24xx_ts_set_platdata(&mini2440_ts_info);

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxMTUzNDcxNTAz_size_16_color_FFFFFF_t_70 4]  
**找到`mini2440_devices`这个结构，添加：**

&s3c_device_lcd,
    	&s3c_device_adc,
    	&s3c_device_ts,
    	&mini2440_beep,

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxMTUzNDcxNTAz_size_16_color_FFFFFF_t_70 5]

**修改内核自带的触摸屏驱动：**

gedit drivers/input/touchscreen/s3c2410_ts.c

**找到`touch_timer_fire`函数，定位到上报触摸事件这一句：**

input_report_key(ts.input, BTN_TOUCH, 1);

**下方添加按压事件上报：**

input_report_abs(ts.input, ABS_PRESSURE, 1);

**找到：**

input_report_key(ts.input, BTN_TOUCH, 0);

**下放添加：**

input_report_abs(ts.input, ABS_PRESSURE, 0);

**如下图所示：**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxMTUzNDcxNTAz_size_16_color_FFFFFF_t_70 6]  
**找到`s3c2410ts_probe`函数，将：**

ts.input->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);

**改为：**

ts.input->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS) | BIT(EV_SYN);

**找到这一句：**

input_set_abs_params(ts.input, ABS_Y, 0, 0x3FF, 0, 0);

**下方添加：**

input_set_abs_params(ts.input, ABS_PRESSURE, 0, 1, 0, 0);

**如下图所示：**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxMTUzNDcxNTAz_size_16_color_FFFFFF_t_70 7]

**重新make编译一下然后下载到开发板运行，LCD屏幕会显示一个linux的企鹅logo，LED1会闪烁！**

### （三）驱动测试 ###

#### （1）测试LED ####

**LED是以平台总线设备驱动的方式进行注册的，LED的相关代码已经标明了ID是1-4，BEEP是以led平台设备驱动进行方式注册的，ID为5，linux的led子系统会在/sys/class目录下生成leds文件夹，进入该目录就可以看到我们以led平台总线驱动方式注册的所有设备：**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxMTUzNDcxNTAz_size_16_color_FFFFFF_t_70 8]  
**可以看到有led1-4和beep，我们使用led4进行测试，进入led4文件夹：**  
![在这里插入图片描述][20200417104016599.png]  
**brightness这个文件就是led4的设备文件，操作这个文件就可以实现led4的亮和灭：**

*  点亮：echo 1 > brightness
 *  熄灭：echo 0 > brightness

#### （2）测试BEEP ####

**同led，进入beep文件夹：**  
![在这里插入图片描述][20200417104512263.png]  
**操作方式跟led一样：**

*  打开蜂鸣器：echo 1 > brightness
 *  熄灭蜂鸣器：echo 0 > brightness

#### （3）测试LCD显示 ####

**这里我使用Img2Lcd这个软件将衣服图片转成了bin文件，然后将该文件拷贝到了开发板文件系统上的/app/目录下：**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxMTUzNDcxNTAz_size_16_color_FFFFFF_t_70 9]  
**lcd帧缓冲的设备文件是/dev/fb0，在开发板上使用cat命令将图片bin输出到显示设备上：**

cat /app/logo.bin > /dev/fb0

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxMTUzNDcxNTAz_size_16_color_FFFFFF_t_70 10]

#### （4）测试触摸屏和按键 ####

**使用以下命令触摸屏幕或按下按键查看有无乱码输出：**

cat /dev/event0
    cat /dev/event1

**注意：如果在内核代码中没有修改名字的话，输入设备文件的默认名就是/dev/eventX，X是数字，在本次移植中有两个输入设备：①触摸屏，②按键，所以在/dev目录下有event0和event1这两个设备文件。**

--------------------

## （四）USB驱动：U盘、USB鼠标键盘 ##

make meunconfig

**关于USB键盘和U盘的配置如下**

Device Drivers  ---> 
    	SCSI device support  --->
    		<*> SCSI device support
    		[*] legacy /proc/scsi/ support
    		<*> SCSI disk support
    	[*] USB support  ---> 
    		<*>   Support for Host-side USB
    		[*]     Dynamic USB minor allocation
    		<*>     USB Monitor
    		<*>     OHCI HCD (USB 1.1) support
    			<*>       OHCI support for Samsung S3C24xx/S3C64xx SoC series
    		<*>     USB Mass Storage support
    	HID support  --->
    		USB HID support  --->
    			<*> USB HID transport layer 
    			[*] PID device support
    			[*] /dev/hiddev raw HID device support

**除此之外还要将字符级编译进内核，你可以使用拿个就编译进哪个，我为了方便将基本的字符级全都编译进去了，缺点是内核大小大概增加了500KB的大小：**

Device Drivers  ---> 
     	File systems  --->
     		-*- Native language support  --->

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxMTUzNDcxNTAz_size_16_color_FFFFFF_t_70 11]

**启动内核，插入U盘后成功识别，可以看到设备节点是sda4，下面挂载U盘：**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxMTUzNDcxNTAz_size_16_color_FFFFFF_t_70 12]  
**我的U盘文件系统格式是FAT32，挂载U盘命令：**

mount -t vfat -o iocharset=cp936 /dev/sda4 /mnt/udisk

*命令解释：*

*  \-t：文件系统类型，vfat代表挂载的U盘格式为FAT/FAT32
 *  \-o：字符集
 *  /dev/sda4：U盘的设备文件
 *  /mnt/udisk：挂载点

*注：一般情况下当有USB或者SD设备插入时，linux内核会首先扫描/etc/mdev.conf的配置文件，从其中获取挂载命令和挂载点从而实现自动挂载。*

**插入USB鼠标：**  
![在这里插入图片描述][20200421112916529.png]

**测试usb鼠标：**

cat /dev/mouseN

*注意：/dev目录下可能有多个mouseN设备文件，N为数字，键入命令后移动鼠标查看有无乱码输出，若没有则不是鼠标的设备文件，挨个试试。*

--------------------

完！

[https_yaffs.net_get-yaffs]: https://yaffs.net/get-yaffs
[https_mirror.bjtu.edu.cn_kernel_linux_kernel]: https://mirror.bjtu.edu.cn/kernel/linux/kernel/
[Linux_yaffs]: https://blog.csdn.net/qq153471503/article/details/105527886
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[20200417104016599.png]: /images/20230528/4134d02e9dd94b0f83b78e34b9abb878.png
[20200417104512263.png]: /images/20230528/5f1c925e8f97404f9c26518db1007e0c.png
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[20200421112916529.png]: /images/20230528/a0538155065345a989c5c38c3bc8ebb3.png