u-boot的board.c详解

你的名字 2021-07-26 15:47 230阅读 0赞

board.c是start.S后的第一个入口文件。

源代码如下：

/* * (C) Copyright 2002-2006 * Wolfgang Denk, DENX Software Engineering, wd@denx.de. * * (C) Copyright 2002 * Sysgo Real-Time Solutions, GmbH <www.elinos.com> * Marius Groeger <mgroeger@sysgo.de> * * See file CREDITS for list of people who contributed to this * project. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License as * published by the Free Software Foundation; either version 2 of * the License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, * MA 02111-1307 USA */
    
    /* * To match the U-Boot user interface on ARM platforms to the U-Boot * standard (as on PPC platforms), some messages with debug character * are removed from the default U-Boot build. * * Define DEBUG here if you want additional info as shown below * printed upon startup: * * U-Boot code: 00F00000 -> 00F3C774 BSS: -> 00FC3274 * IRQ Stack: 00ebff7c * FIQ Stack: 00ebef7c */
    
    #include <common.h>
    #include <command.h>
    #include <malloc.h>
    #include <stdio_dev.h>
    #include <timestamp.h>
    #include <version.h>
    #include <net.h>
    #include <serial.h>
    #include <nand.h>
    #include <onenand_uboot.h>
    #include <mmc.h>
    #include <asm/arch/s3c24x0_cpu.h> //tekkamanninja
    #include <asm/io.h> //tekkamanninja
    
    #ifdef CONFIG_BITBANGMII
    #include <miiphy.h>
    #endif
    
    #ifdef CONFIG_DRIVER_SMC91111
    #include "../drivers/net/smc91111.h"
    #endif
    #ifdef CONFIG_DRIVER_LAN91C96
    #include "../drivers/net/lan91c96.h"
    #endif
    
    DECLARE_GLOBAL_DATA_PTR;
    
    ulong monitor_flash_len;
    
    #ifdef CONFIG_HAS_DATAFLASH
    extern int  AT91F_DataflashInit(void);
    extern void dataflash_print_info(void);
    #endif
    
    #ifdef CONFIG_USB_DEVICE
    extern void usb_init_slave(void);
    #endif
    
    #ifndef CONFIG_IDENT_STRING
    #define CONFIG_IDENT_STRING ""
    #endif
    
    const char version_string[] =
    	U_BOOT_VERSION" (" U_BOOT_DATE " - " U_BOOT_TIME ")"CONFIG_IDENT_STRING;
    
    #ifdef CONFIG_DRIVER_RTL8019
    extern void rtl8019_get_enetaddr (uchar * addr);
    #endif
    
    #if defined(CONFIG_HARD_I2C) || \ defined(CONFIG_SOFT_I2C)
    #include <i2c.h>
    #endif
    
    #if 0
    /************************************************************************ * Coloured LED functionality ************************************************************************ * May be supplied by boards if desired */
    void inline __coloured_LED_init (void) { }
    void coloured_LED_init (void) __attribute__((weak, alias("__coloured_LED_init")));
    void inline __red_LED_on (void) { }
    void red_LED_on (void) __attribute__((weak, alias("__red_LED_on")));
    void inline __red_LED_off(void) { }
    void red_LED_off(void) __attribute__((weak, alias("__red_LED_off")));
    void inline __green_LED_on(void) { }
    void green_LED_on(void) __attribute__((weak, alias("__green_LED_on")));
    void inline __green_LED_off(void) { }
    void green_LED_off(void) __attribute__((weak, alias("__green_LED_off")));
    void inline __yellow_LED_on(void) { }
    void yellow_LED_on(void) __attribute__((weak, alias("__yellow_LED_on")));
    void inline __yellow_LED_off(void) { }
    void yellow_LED_off(void) __attribute__((weak, alias("__yellow_LED_off")));
    void inline __blue_LED_on(void) { }
    void blue_LED_on(void) __attribute__((weak, alias("__blue_LED_on")));
    void inline __blue_LED_off(void) { }
    void blue_LED_off(void) __attribute__((weak, alias("__blue_LED_off")));
    #endif
    
    /************************************************************************ * Init Utilities * ************************************************************************ * Some of this code should be moved into the core functions, * or dropped completely, * but let's get it working (again) first... */
    
    #if defined(CONFIG_ARM_DCC) && !defined(CONFIG_BAUDRATE)
    #define CONFIG_BAUDRATE 115200
    #endif
    static int init_baudrate (void)
    { 
    	char tmp[64];	/* long enough for environment variables */
    	int i = getenv_r ("baudrate", tmp, sizeof (tmp));
    	gd->bd->bi_baudrate = gd->baudrate = (i > 0)
    			? (int) simple_strtoul (tmp, NULL, 10)
    			: CONFIG_BAUDRATE;
    
    	return (0);
    }
    
    static int display_banner (void)
    { 
    #if defined(CONFIG_MINI2440_LED) 
    	struct s3c24x0_gpio * const gpio = s3c24x0_get_base_gpio();
    	writel(0x101, &gpio->GPBDAT);  //tekkamanninja
    #endif
    	printf ("\n\n%s\n\n", version_string);	
    	printf (" modified by tekkamanninja (tekkamanninja@163.com)\n");
    	printf (" Love Linux forever!!\n\n");
    	debug ("U-Boot code: %08lX -> %08lX BSS: -> %08lX\n",
    	       _armboot_start, _bss_start, _bss_end);
    #ifdef CONFIG_MODEM_SUPPORT
    	debug ("Modem Support enabled\n");
    #endif
    #ifdef CONFIG_USE_IRQ
    	debug ("IRQ Stack: %08lx\n", IRQ_STACK_START);
    	debug ("FIQ Stack: %08lx\n", FIQ_STACK_START);
    #endif
    
    	return (0);
    }
    
    /* * WARNING: this code looks "cleaner" than the PowerPC version, but * has the disadvantage that you either get nothing, or everything. * On PowerPC, you might see "DRAM: " before the system hangs - which * gives a simple yet clear indication which part of the * initialization if failing. */
    static int display_dram_config (void)
    { 
    	int i;
    
    #ifdef DEBUG
    	puts ("RAM Configuration:\n");
    
    	for(i=0; i<CONFIG_NR_DRAM_BANKS; i++) { 
    		printf ("Bank #%d: %08lx ", i, gd->bd->bi_dram[i].start);
    		print_size (gd->bd->bi_dram[i].size, "\n");
    	}
    #else
    	ulong size = 0;
    
    	for (i=0; i<CONFIG_NR_DRAM_BANKS; i++) { 
    		size += gd->bd->bi_dram[i].size;
    	}
    	puts("DRAM: ");
    	print_size(size, "\n");
    #endif
    
    	return (0);
    }
    
    #ifndef CONFIG_SYS_NO_FLASH
    static void display_flash_config (ulong size)
    { 
    	puts ("Flash: ");
    	print_size (size, "\n");
    }
    #endif /* CONFIG_SYS_NO_FLASH */
    
    #if defined(CONFIG_HARD_I2C) || defined(CONFIG_SOFT_I2C)
    static int init_func_i2c (void)
    { 
    	puts ("I2C: ");
    	i2c_init (CONFIG_SYS_I2C_SPEED, CONFIG_SYS_I2C_SLAVE);
    	puts ("ready\n");
    	return (0);
    }
    #endif
    
    #if defined(CONFIG_CMD_PCI) || defined (CONFIG_PCI)
    #include <pci.h>
    static int arm_pci_init(void)
    { 
    	pci_init();
    	return 0;
    }
    #endif /* CONFIG_CMD_PCI || CONFIG_PCI */
    
    /* * Breathe some life into the board... * * Initialize a serial port as console, and carry out some hardware * tests. * * The first part of initialization is running from Flash memory; * its main purpose is to initialize the RAM so that we * can relocate the monitor code to RAM. */
    
    /* * All attempts to come up with a "common" initialization sequence * that works for all boards and architectures failed: some of the * requirements are just _too_ different. To get rid of the resulting * mess of board dependent #ifdef'ed code we now make the whole * initialization sequence configurable to the user. * * The requirements for any new initalization function is simple: it * receives a pointer to the "global data" structure as it's only * argument, and returns an integer return code, where 0 means * "continue" and != 0 means "fatal error, hang the system". */
    	typedef int (init_fnc_t) (void);	/*声明一个 init_fnc_t 类型（int型）*/
    	
    	int print_cpuinfo (void);
    	/*init_sequence是一个指针数组，指向的是init_fnc_t类型的函数（这样遍历指针数组一次执行所有函数）*/
    	init_fnc_t *init_sequence[] = { 
    #if defined(CONFIG_ARCH_CPU_INIT)
    		arch_cpu_init,		/* basic arch cpu dependent setup >>这里没有被使用<<*/ 
    #endif
    		board_init, 	/* basic board dependent setup 板级初始化*/
    #if defined(CONFIG_USE_IRQ)
    		interrupt_init, 	/* set up exceptions 中断初始化*/
    #endif
    		timer_init, 	/* initialize timer 定时器初始化*/
    #ifdef CONFIG_FSL_ESDHC
    		get_clocks,
    #endif
    		env_init,		/* initialize environment 环境变量初始化*/
    		init_baudrate,		/* initialze baudrate settings 波特率初始化*/
    		serial_init,		/* serial communications setup 串口初始化*/
    		console_init_f, 	/* stage 1 init of console 终端初始化*/
    		display_banner, 	/* say that we are here 打印信息*/
    #if defined(CONFIG_DISPLAY_CPUINFO)
    		print_cpuinfo,		/* display cpu info (and speed) 打印cpu信息*/
    #endif
    #if defined(CONFIG_DISPLAY_BOARDINFO)
    		checkboard, 	/* display board info */
    #endif
    #if defined(CONFIG_HARD_I2C) || defined(CONFIG_SOFT_I2C) /*I2C初始化*/
    		init_func_i2c,
    #endif
    		dram_init,		/* configure available RAM banks */
    #if defined(CONFIG_CMD_PCI) || defined (CONFIG_PCI)
    		arm_pci_init,
    #endif
    		display_dram_config,
    		NULL,
    	};
    
    /*入口函数，start.S后执行的第一个函数*/
    void start_armboot (void)
    { 
    	init_fnc_t **init_fnc_ptr;/*init_fnc_ptr为指向函数指针的指针*/
    	char *s;
    #if defined(CONFIG_VFD) || defined(CONFIG_LCD)
    	unsigned long addr;
    #endif
    #if defined(CONFIG_MINI2440_LED) 
    	struct s3c24x0_gpio * const gpio = s3c24x0_get_base_gpio();  //gpio是指向以0x56000000为基地址的s3c24x0_gpio结构体指针
    #endif
    	/* Pointer is writable since we allocated a register for it */
    	gd = (gd_t*)(_armboot_start - CONFIG_SYS_MALLOC_LEN - sizeof(gd_t));  //初始化gd指针，gd指向一个可用的内存地址
    	/* compiler optimization barrier needed for GCC >= 3.4 */
    	__asm__ __volatile__("": : :"memory");
    
    	memset ((void*)gd, 0, sizeof (gd_t));
    	gd->bd = (bd_t*)((char*)gd - sizeof(bd_t));
    	memset (gd->bd, 0, sizeof (bd_t));
    
    	gd->flags |= GD_FLG_RELOC;
    /*这里需要注意的是_bss_start和_armboot_start在汇编中引用表示地址，而在C中，对汇编中的全局标号的引用，其值不再是地址，而是地址对应内存单元中的数据*/
    	monitor_flash_len = _bss_start - _armboot_start;
    /*遍历执行初始化函数*/
    /*init_fnc_ptr初始化指向init_sequence指针数组，下面的循环遇到NULL结束*/
    /*init_fnc_ptr ()和init_sequence; 只是(*init_fnc_ptr )();简写形式而已。我们之所以可以init_fnc_ptr ();这样调用函数，只是编译器帮我们做了调整而已。*/
    	for (init_fnc_ptr = init_sequence; *init_fnc_ptr; ++init_fnc_ptr) { 
    		if ((*init_fnc_ptr)() != 0) { /*(*init_fnc_ptr)()为C中调用指针指向的函数*/
    			hang ();
    		}
    	
    	}
    /*mem_malloc_init()函数为malloc申请内存空间：*/
    	/* armboot_start is defined in the board-specific linker script */
    	mem_malloc_init (_armboot_start - CONFIG_SYS_MALLOC_LEN,
    			CONFIG_SYS_MALLOC_LEN);
    /*增加对NorFlash的支持*/
    #ifndef CONFIG_SYS_NO_FLASH
    	/* configure available FLASH banks */
    	display_flash_config (flash_init ());  /*初始化flash*/
    #endif /* CONFIG_SYS_NO_FLASH */
    
    #ifdef CONFIG_VFD
    # ifndef PAGE_SIZE
    # define PAGE_SIZE 4096
    # endif
    	/* * reserve memory for VFD display (always full pages) */
    	/* bss_end is defined in the board-specific linker script */
    	addr = (_bss_end + (PAGE_SIZE - 1)) & ~(PAGE_SIZE - 1);
    	vfd_setmem (addr);
    	gd->fb_base = addr;
    #endif /* CONFIG_VFD */
    
    #ifdef CONFIG_LCD
    	/* board init may have inited fb_base */
    	if (!gd->fb_base) { 
    # ifndef PAGE_SIZE
    # define PAGE_SIZE 4096
    # endif
    		/* * reserve memory for LCD display (always full pages) */
    		/* bss_end is defined in the board-specific linker script */
    		addr = (_bss_end + (PAGE_SIZE - 1)) & ~(PAGE_SIZE - 1);
    		lcd_setmem (addr);
    		gd->fb_base = addr;
    	}
    #endif /* CONFIG_LCD */
    
    #if defined(CONFIG_CMD_NAND)
    	puts ("NAND: ");
    	nand_init();		/* go init the NAND */
    #endif
    
    #if defined(CONFIG_CMD_ONENAND)
    	onenand_init();
    #endif
    
    #ifdef CONFIG_HAS_DATAFLASH
    	AT91F_DataflashInit();
    	dataflash_print_info();
    #endif
    
    	/* initialize environment */
    	env_relocate ();
    
    #ifdef CONFIG_VFD
    	/* must do this after the framebuffer is allocated */
    	drv_vfd_init();
    #endif /* CONFIG_VFD */
    
    #ifdef CONFIG_SERIAL_MULTI
    	serial_initialize();
    #endif
    
    	/* IP Address */
    	gd->bd->bi_ip_addr = getenv_IPaddr ("ipaddr");
    
    	stdio_init ();	/* get the devices list going. */
    
    	jumptable_init ();
    
    #if defined(CONFIG_API)
    	/* Initialize API */
    	api_init ();
    #endif
    
    	console_init_r ();	/* fully init console as a device */
    
    #if defined(CONFIG_ARCH_MISC_INIT)
    	/* miscellaneous arch dependent initialisations */
    	arch_misc_init ();
    #endif
    #if defined(CONFIG_MISC_INIT_R)
    	/* miscellaneous platform dependent initialisations */
    	misc_init_r ();
    #endif
    	/* enable exceptions */
    	enable_interrupts ();
    
    #ifdef CONFIG_USB_DEVICE
    	usb_init_slave();
    #endif
    	/* Perform network card initialisation if necessary */
    #ifdef CONFIG_DRIVER_TI_EMAC
    	/* XXX: this needs to be moved to board init */
    extern void davinci_eth_set_mac_addr (const u_int8_t *addr);
    	if (getenv ("ethaddr")) { 
    		uchar enetaddr[6];
    		eth_getenv_enetaddr("ethaddr", enetaddr);
    		davinci_eth_set_mac_addr(enetaddr);
    	}
    #endif
    
    #if defined(CONFIG_DRIVER_SMC91111) || defined (CONFIG_DRIVER_LAN91C96)
    	/* XXX: this needs to be moved to board init */
    	if (getenv ("ethaddr")) { 
    		uchar enetaddr[6];
    		eth_getenv_enetaddr("ethaddr", enetaddr);
    		smc_set_mac_addr(enetaddr);
    	}
    #endif /* CONFIG_DRIVER_SMC91111 || CONFIG_DRIVER_LAN91C96 */
    
    	/* Initialize from environment */
    	if ((s = getenv ("loadaddr")) != NULL) { 
    		load_addr = simple_strtoul (s, NULL, 16);
    	}
    #if defined(CONFIG_CMD_NET)
    	if ((s = getenv ("bootfile")) != NULL) { 
    		copy_filename (BootFile, s, sizeof (BootFile));
    	}
    #endif
    
    #ifdef BOARD_LATE_INIT
    	board_late_init ();
    #endif
    
    #ifdef CONFIG_GENERIC_MMC
    	puts ("MMC: ");
    	mmc_initialize (gd->bd);
    #endif
    
    #ifdef CONFIG_BITBANGMII
    	bb_miiphy_init();
    #endif
    #if defined(CONFIG_CMD_NET)
    #if defined(CONFIG_NET_MULTI)
    	puts ("Net: ");
    #endif
    	eth_initialize(gd->bd);
    #if defined(CONFIG_RESET_PHY_R)
    	debug ("Reset Ethernet PHY\n");
    	reset_phy();
    #endif
    #endif
    #if defined(CONFIG_MINI2440_LED) 
    	writel(0x0, &gpio->GPBDAT);  //tekkamanninja
    #endif
     
    #if defined(CONFIG_CFB_CONSOLE) 
    	printf ("%s\n", version_string);
    	printf ("modified by tekkamanninja\n(tekkamanninja@163.com)\n");
    	printf ("Love Linux forever!!\n");
    #endif
    	/* main_loop() can return to retry autoboot, if so just run it again. */
    	for (;;) { 
    		main_loop ();
    	}
    
    	/* NOTREACHED - no way out of command loop except booting */
    }
    
    void hang (void)
    { 
    	puts ("### ERROR ### Please RESET the board ###\n");
    	for (;;);
    }

## 关于start\_armboot 详细分析 ##

start\_armboot 是uboot汇编启动代码start.S执行完后的后第一个c函数。

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTI1Nzc0NzQ_size_16_color_FFFFFF_t_70]  
start\_armboot 会马上申请三块空间，一块用来分配给malloc管理，一份用来存储gd\_t,一份用来存储bd\_t （如上图所示）。

1、分配gd空间

gd = (gd_t*)(_armboot_start - CONFIG_SYS_MALLOC_LEN - sizeof(gd_t));

2、分配bd空间

memset ((void*)gd, 0, sizeof (gd_t));
    	gd->bd = (bd_t*)((char*)gd - sizeof(bd_t));
    	memset (gd->bd, 0, sizeof (bd_t));

3、分配malloc空间

mem_malloc_init (_armboot_start - CONFIG_SYS_MALLOC_LEN,
    		CONFIG_SYS_MALLOC_LEN);

malloc（）是动态内存分配函数，用来向系统请求分配内存空间。当无法知道内存具体的位置时，  
想要绑定真正的内存空间，就要用到malloc（）函数。因为malloc只管分配内存空间，并不能对分  
配的空间进行初始化，所以申请到的内存中的值是随机的，经常会使用memset()进行置0操作后再使用。

与其配套的是free（），当申请到的空间不再使用时，要用free（）函数将内存空间释放掉，这样可以  
提高资源利用率，最重要的是----就是因为它可以申请内存空间，然后根据需要进行释放，才被称为“动态内存分配”！

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTI1Nzc0NzQ_size_16_color_FFFFFF_t_70]: /images/20210726/b5701c8c5f2b45a7bea71ded23379d29.png