[Linux bottom layer] U-boot compilation and transplantation

System version: Ubuntu18.04-64

Compiler version: gcc version 7.4.0 (Ubuntu/Linaro 7.4.0-1ubuntu1~18.04.1)

uboot version: 2018.07-linux4sam_6.0

Board model: at91sama5d3x-xplained

MCU model: sama5d36

1. The uboot directory is as follows:

2. There is an official default configuration under the configs/ folder

   # To put environment variables in nandflash (default):

   sama5d3_xplained_nandflash_defconfig

   # To put environment variables in SD/MMC card:

   sama5d3_xplained_mmc_defconfig

Compile for SAMA5D3-Xplained board:

Select nandflash boot

make sama5d3_xplained_nandflash_defconfig

make

3. The uboot downloaded from the official website can basically run, and the printed information can be seen through the serial port. There may be no problem with the DDR2 and NAND Flash drivers and they can be used normally. The network driver and LED driver designed by the manufacturer are adapted and cut according to the model;

Burn the compiled file u-boot.bin into it, and you can see the information printed by the serial port

U-Boot 2018.07-linux4sam_6.0 (Oct 11 2019 - 23:57:20 -0700)

CPU: SAMA5D36

Crystal frequency:       12 MHz

CPU clock        :      528 MHz

Master clock     :      132 MHz

DRAM:  256 MiB

NAND:  256 MiB

MMC:   Atmel mci: 0, Atmel mci: 1

Loading Environment from NAND... OK

In:    serial@ffffee00

Out:   serial@ffffee00

Err:   serial@ffffee00

Netjack:   macb_eth_probe phy-mode=mii,devname=ethernet@f0028000

eth0: ethernet@f0028000 [PRIME]macb_eth_probe phy-mode=rmii,devname=ethernet@f802c000

, eth1: ethernet@f802c000

Hit any key to stop autoboot:  0 

=> at

arch=arm

baudrate=115200

board=sama5d3_xplained

board_name=sama5d3_xplained

bootargs=console=ttyS0,115200 earlyprintk mtdparts=atmel_nand:256k(bootstrap)ro,768k(uboot)ro,256K(env_redundant),256k(env),512k(dtb),6M(kernel)ro,-(rootfs) rootfstype=ubifs ubi.mtd=6 root=ubi0:rootfs

bootcmd=tftp 0x21000000 at91-sama5d3_xplained.dtb;tftp 0x22000000 zImage;bootz 0x22000000 - 0x21000000

bootdelay=3

cpu=armv7

eth1addr=AA:AB:C1:D2:E6:C6

ethact=ethernet@f0028000

ethaddr=EE:AB:C1:D2:E6:C6

ethprime=ethernet@f0028000

fdtcontroladdr=2fb16b08

gatewayip=192.168.1.1

ipaddr=192.168.1.100

ipaddr1=192.168.2.100

netmask=255.255.255.0

serverip=192.168.1.108

soc=at91

stderr=serial@ffffee00

stdin=serial@ffffee00

stdout=serial@ffffee00

vendor=atmel

Environment size: 778/131067 bytes

=> 

4. Key Document Description

scripts/config_whitelist.txt List of all macro definitions

SAMA5D3_XPLAINED BOARD

M: Bo Shen

S: Maintained

F: board/atmel/sama5d3_xplained/sama5d3_xplained.c

F: include/configs/sama5d3_xplained.h

F: configs/sama5d3_xplained_mmc_defconfig

F: configs/sama5d3_xplained_nandflash_defconfig

arch/arm/mach-at91/spl_at91.c

arch/arm/mach-at91/include/mach/at91_common.h //public function declaration header file

sama5d3.h //CPU base address

sama5_boot.h //Boot mode

include/configs at91-sama5_common.h //CPU series common configuration

5. Cropped file list

//============================================

Determine the file of uboot compilation configuration, and the compilation option macro definition is found in these files

include/configs/at91-sama5_common.h

include/configs/sama5d3_xplained.h

configs/sama5d3_xplained_nandflash_defconfig

//

CONFIG_DM_ETH //Support device tree, network configuration is read from the device tree

This version of uboot supports the device tree function, making uboot lighter and no longer bloated and clumsy.

6. Modify the device tree and change the MAC interface mode of the network

arch/arm/dts

Makefile

dtb-$(CONFIG_TARGET_SAMA5D3_XPLAINED) +=

at91-sama5d3_xplained.dtb

macb0: ethernet@f0028000 {

phy-mode = "mii"; //Change the PHY interface mode

#address-cells = <1>;

#size-cells = <0>;

status = "okay";

ethernet-phy@7 {

reg = <0x7>;

};

};

7. Since uboot is a naked running program, it must have a main function. Start with the main function to see how to initialize peripherals, GPIO, network card, etc.

void board_init_r(gd_t *new_gd, ulong dest_addr)

{

    /*

     * Set up the new global data pointer. So far only x86 does this

     * here.

     * TODO(sjg@chromium.org): Consider doing this for all archs, or

     * dropping the new_gd parameter.

     */

#if CONFIG_IS_ENABLED(X86_64)

    arch_setup_gd(new_gd);

#endif

#ifdef CONFIG_NEEDS_MANUAL_RELOC

    int i;

#endif

#if !defined(CONFIG_X86) && !defined(CONFIG_ARM) && !defined(CONFIG_ARM64)

    gd = new_gd;

#endif

    gd->flags &= ~GD_FLG_LOG_READY;

#ifdef CONFIG_NEEDS_MANUAL_RELOC

    for (i = 0; i < ARRAY_SIZE(init_sequence_r); i++)

        init_sequence_r[i] += gd->reloc_off;

#endif

//All initialization depends on this array

    if (initcall_run_list(init_sequence_r))

        hang();

    /* NOTREACHED - run_main_loop() does not return */

    hang();

}

//Execute functions sequentially in the structure

//Execute functions sequentially in the structure

//Excerpt part of the code, there are many devices in the array, initialize

static init_fnc_t init_sequence_r[] = {

/* PPC has a udelay(20) here dating from 2002. Why? */

#ifdef CONFIG_CMD_NET

    initr_ethaddr, // Network device information initialization     

#endif

#ifdef CONFIG_CMD_NET

    INIT_FUNC_WATCHDOG_RESET  

    initr_net, //Initialize network devices, uboot prints the read network card information

#endif

PHY initialization process

eth_initialize(); //First level initialization of network equipment

eth_common_init(); //Second level initialization of network equipment

miiphy_init(); //Network device third level initialization

phy_init();//

phy_davicom_init(); //Network device fourth level initialization

phy_micrel_ksz8xxx_init();//

MDIO mii MAC+PHY=network card chip, the first 5 registers are the same for all PHY chips;

8. Set the board-level hardware clock configuration

arch/arm/mach-at91/spl_atmel.c

void board_init_f(head dummy)

{

    int ret;

    switch_to_main_crystal_osc();

#ifdef CONFIG_SAMA5D2

    configure_2nd_sram_as_l2_cache();

#endif

#if !defined(CONFIG_AT91SAM9_WATCHDOG)

    /* disable watchdog */

    at91_disable_wdt();

#endif

    /* PMC configuration */

    at91_pmc_init();

    at91_clock_init(CONFIG_SYS_AT91_MAIN_CLOCK);

    matrix_init();

    redirect_int_from_saic_to_aic();

    timer_init();

    board_early_init_f();

    mem_init();

    ret = spl_init();

    if (ret) {

        debug("spl_init() failed: %dn", ret);

        hang();

    }

    preloader_console_init();

9. CPU related settings

arch/arm/cpu/armv7

10. Board level information

board/atmel/sama5d3_xplained/sama5d3_xplained.c

int board_init(void)

{

    /* adress of boot parameters */

    gd->bd->bi_boot_params = CONFIG_SYS_SDRAM_BASE + 0x100;

#ifdef CONFIG_NAND_ATMEL

    sama5d3_xplained_nand_hw_init(); //Nand Flash initialization

#endif

#ifdef CONFIG_CMD_USB

    sama5d3_xplained_usb_hw_init(); //USB initialization

#endif

#ifdef CONFIG_GENERIC_ATMEL_MCI

    sama5d3_xplained_mci0_hw_init(); //EMMC initialization

#endif

    return 0;

}

11. The RESET pin of PHY 9031 is controlled by the CPU, and the power supply and RESET of PHY 8081 are controlled by the CPU. To ensure the timing, after the system is powered on, the RST pin of the PHY chip is pulled high first;

Control GPIO operation under uboot

board/atmel/sama5d3_xplained/sama5d3_xplained.c

Add code

tatic void sama5d3_xplained_phy_hw_init(void)

{

    //GPIO register configuration, output internal pull-up function;

    at91_set_pio_periph(AT91_PIO_PORTE, 9, 1);      /* GPIO output up*/

    at91_set_pio_periph(AT91_PIO_PORTC, 18, 1);         /* GPIO output up*/

    at91_set_pio_periph(AT91_PIO_PORTC, 31, 1);         /* GPIO output up*/

    at91_set_pio_periph(AT91_PIO_PORTB, 12, 1);         /* LED GPIO output up*/

        //Output corresponding level

    at91_set_pio_output(AT91_PIO_PORTE, 9, 1);      //micrel ksz9031 reset gpio

    at91_set_pio_output(AT91_PIO_PORTC, 18, 0);     //micrel ksz8081 power gpio

    at91_set_pio_output(AT91_PIO_PORTC, 31, 1);     //micrel ksz8081 reset gpio

    at91_set_pio_output(AT91_PIO_PORTB, 12, 0);     //Board led on

}

int board_init(void)

{

    /* adress of boot parameters */

    gd->bd->bi_boot_params = CONFIG_SYS_SDRAM_BASE + 0x100;

#ifdef CONFIG_NAND_ATMEL

    sama5d3_xplained_nand_hw_init();

#endif

#ifdef CONFIG_CMD_USB

    sama5d3_xplained_usb_hw_init();

#endif

#ifdef CONFIG_GENERIC_ATMEL_MCI

    sama5d3_xplained_mci0_hw_init();

#endif

    // add by for Jack phy init gpio

        //Add the GPIO initialization function to the initialization function of the development board and call

    sama5d3_xplained_phy_hw_init();

    return 0;

}

12. The official website uboot download link is:

https://www.linux4sam.org/bin/view/Linux4SAM/U-Boot