1.     TI AM335x  内核源码分析

1.1 Board-am335xevm.c

Board-am335xevm.c(./arch/arm/mach-omap2)中开始执行入口：

MACHINE_START(AM335XEVM,"am335xevm")

/* Maintainer: Texas Instruments */

.atag_offset     = 0x100,

.map_io             =am335x_evm_map_io,

.init_early         = am33xx_init_early,

.init_irq    = ti81xx_init_irq,

.handle_irq     = omap3_intc_handle_irq,

.timer                =&omap3_am33xx_timer,

.init_machine  = am335x_evm_init,

MACHINE_END

MACHINE_START(AM335XIAEVM,"am335xiaevm")

/* Maintainer: Texas Instruments */

.atag_offset     = 0x100,

.map_io             =am335x_evm_map_io,

.init_irq    = ti81xx_init_irq,

.init_early         = am33xx_init_early,

.timer                =&omap3_am33xx_timer,

.init_machine  = am335x_evm_init,

MACHINE_END

1.2 am335x_evm_init

static void__init am335x_evm_init(void)

{

am33xx_cpuidle_init();

am33xx_mux_init(board_mux);

omap_serial_init();

am335x_evm_i2c_init();

//daughter_brd_detected = false;

am335x_evm_setup(NULL,NULL);                              //Tbao--------

omap_sdrc_init(NULL, NULL);

usb_musb_init(&musb_board_data);

omap_board_config = am335x_evm_config;

omap_board_config_size =ARRAY_SIZE(am335x_evm_config);

//setup_general_purpose_evm();

/* Create an alias for icss clock */

if (clk_add_alias("pruss",NULL, "pruss_uart_gclk", NULL))

pr_warn("failed tocreate an alias: icss_uart_gclk --> pruss\n");

/* Create an alias for gfx/sgx clock */

if (clk_add_alias("sgx_ck",NULL, "gfx_fclk", NULL))

pr_warn("failed tocreate an alias: gfx_fclk --> sgx_ck\n");

}

1.3 am335x_evm_setup

static voidam335x_evm_setup(struct memory_accessor *mem_acc, void *context)

{

setup_general_purpose_evm();

return;

#if 0

/* 1st get the MAC address from EEPROM*/

ret = mem_acc->read(mem_acc, (char*)&am335x_mac_addr,

EEPROM_MAC_ADDRESS_OFFSET,sizeof(am335x_mac_addr));

if (ret != sizeof(am335x_mac_addr)) {

pr_warning("AM335X: EVMConfig read fail: %d\n", ret);

return;

}

#endif

/* Fillup global mac id */

//am33xx_cpsw_macidfillup(&am335x_mac_addr[0][0],

//                         &am335x_mac_addr[1][0]);

#if 0

/* get board specific data */

ret = mem_acc->read(mem_acc, (char*)&config, 0, sizeof(config));

if (ret != sizeof(config)) {

pr_err("AM335X EVMconfig read fail, read %d bytes\n", ret);

pr_err("This likelymeans that there either is no/or a failed EEPROM\n");

goto out;

}

if (config.header !=AM335X_EEPROM_HEADER) {

pr_err("AM335X: wrongheader 0x%x, expected 0x%x\n",

config.header,AM335X_EEPROM_HEADER);

goto out;

}

if (strncmp("A335",config.name, 4)) {

pr_err("Board%s\ndoesn't look like an AM335x board\n",

config.name);

goto out;

}

snprintf(tmp, sizeof(config.name) + 1,"%s", config.name);

pr_info("Board name: %s\n",tmp);

snprintf(tmp, sizeof(config.version) +1, "%s", config.version);

pr_info("Board version:%s\n", tmp);

if (!strncmp("A335BONE",config.name, 8)) {

daughter_brd_detected =false;

if(!strncmp("00A1",config.version, 4) ||

!strncmp("00A2", config.version,4))

setup_beaglebone_old();

else

setup_beaglebone();

} else if (!strncmp("A335BNLT",config.name, 8)) {

setup_beagleboneblack();

} else if(!strncmp("A335X_SK", config.name, 8)) {

daughter_brd_detected =false;

#endif

//setup_starterkit();

#if 0

} else {

/* only 6 characters ofoptions string used for now */

snprintf(tmp, 7,"%s", config.opt);

pr_info("SKU:%s\n", tmp);

if(!strncmp("SKU#01", config.opt, 6))

setup_general_purpose_evm();

else if(!strncmp("SKU#02", config.opt, 6))

setup_ind_auto_motor_ctrl_evm();

else

goto out;

}

am335x_opp_update();

/*

* For now, Beaglebone Black uses PG 2.0 thatare speed binned and operate

* up to 1GHz. So re-enable Turbo and Nitromodes,

*/

if (!strncmp("A335BNLT",config.name, 8)) {

struct device *mpu_dev;

mpu_dev = omap_device_get_by_hwmod_name("mpu");

opp_enable(mpu_dev,

AM33XX_ES2_0_OPPTURBO_FREQ);

opp_enable(mpu_dev,

AM33XX_ES2_0_OPPNITRO_FREQ);

}

#endif

1.4 setup_general_purpose_evm

static voidsetup_general_purpose_evm(void)

{

u32prof_sel = am335x_get_profile_selection();

u32boardid = GEN_PURP_EVM;

if(!strncmp("1.5A", config.version, 4))

boardid= GEN_PURP_DDR3_EVM;

pr_info("Theboard is general purpose EVM %sin profile %d\n",

((boardid== GEN_PURP_DDR3_EVM) ? "with DDR3 " : ""),

prof_sel);

_configure_device(boardid,invt_evm_dev_cfg, -1);   //*****Tbao*****

am33xx_cpsw_init(AM33XX_CPSW_MODE_RMII,NULL, NULL);

/*Atheros Tx Clk delay Phy fixup */

phy_register_fixup_for_uid(AM335X_EVM_PHY_ID,AM335X_EVM_PHY_MASK,

beaglebone_phy_fixup);

}

_configure_device初始化：结构体很重要，初始化就是初始化这些函数指针结构体

static struct evm_dev_cfginvt_evm_dev_cfg[] = {

{enable_ecap0,        DEV_ON_BASEBOARD, PROFILE_NONE},

{lcdc_init,          DEV_ON_BASEBOARD, PROFILE_NONE},

{mfd_tscadc_init,    DEV_ON_BASEBOARD, PROFILE_NONE},

{rmii1_init,       DEV_ON_BASEBOARD, PROFILE_NONE},

{rmii2_init,       DEV_ON_BASEBOARD, PROFILE_NONE},

{usb0_init,        DEV_ON_BASEBOARD, PROFILE_NONE},

{usb1_init,        DEV_ON_BASEBOARD, PROFILE_NONE},

{evm_nand_init,DEV_ON_BASEBOARD,PROFILE_NONE},

{mmc0_init,     DEV_ON_BASEBOARD, PROFILE_NONE},

{spi0_init,         DEV_ON_BASEBOARD, PROFILE_NONE},

//{uart1_init,   DEV_ON_DGHTR_BRD, PROFILE_NONE},

//{switch1_init,        DEV_ON_DGHTR_BRD, PROFILE_NONE},

//{poweroff_init,      DEV_ON_DGHTR_BRD, PROFILE_NONE},

{NULL,0,0},

};

1.5 _configure_device

static void _configure_device(intevm_id, struct evm_dev_cfg *dev_cfg,

intprofile)

{

inti;

am335x_evm_set_id(evm_id);

if(profile == PROFILE_NONE) {

for(i = 0; dev_cfg->device_init != NULL; dev_cfg++) {

if(dev_cfg->device_on == DEV_ON_BASEBOARD)

dev_cfg->device_init(evm_id,profile);

elseif (daughter_brd_detected == true)

dev_cfg->device_init(evm_id,profile);

}

}else {

for(i = 0; dev_cfg->device_init != NULL; dev_cfg++) {

if(dev_cfg->profile & profile) {

if(dev_cfg->device_on == DEV_ON_BASEBOARD)

dev_cfg->device_init(evm_id,profile);

elseif (daughter_brd_detected == true)

dev_cfg->device_init(evm_id,profile);

}

}

}

}

1.6nand_base.c (drivers/mtd/nand)

在nand_base.c(drivers/mtd/nand) 中nand_scan_tail函数中加红色部分，加载文件系统：

/* Allow subpagewrites up to ecc.steps. Not possible for MLC flash */

if (!(chip->options &NAND_NO_SUBPAGE_WRITE) &&

!(chip->cellinfo & NAND_CI_CELLTYPE_MSK)) {

switch (chip->ecc.steps) {

case 2:

mtd->subpage_sft= 1;

break;

case 4:

case 8:

case 16:

mtd->subpage_sft= 2;

break;

}

mtd->subpage_sft= 0; //Tbao****************

}

chip->subpagesize =mtd->writesize >> mtd->subpage_sft;