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AM3352: I2C usage in SPL and U-boot

Rohit Kotak
Intellectual 760 points

Part Number: AM3352

Hi,

I am using am3352 processor and have one carypto authentication chip connected on i2c2. Purpose of the communication with this chip is to authenticate the software at boot time and communicate at SPL level is to authenticate u-boot before handing over the command of boot process to u-boot.

I cloned the u-boot for ti 2018 and understood that common/spl/ participate in creating MLO and board/ti/am335x participate in generating u-boot.img while compiling the u-boot. is this correct? How to enable & use I2C2 at SPL & u-boot level?

Regards,

Rohit

CONFIG_SPL_BOARD_INIT
  • 0
    TI__Guru 65405 points

    Hi Rohit,

    Please, refer to linked below E2E thread which describing I2C2 u-boot configuration for Sitara am335x:
    e2e.ti.com/.../508057

    BR
    Tsvetolin Shulev

  • 0 in reply to Cvetolin Shulev-XID
    Intellectual 760 points

    Hi Tsvetolin,

    Thanks for your quick reply.

    I followed the steps mentioned in your suggested thread to enable I2C2 in u-boot and found that I2C2 is still not working. I verified it using performing read & write after I2C init, where I am able to perform read & write for I2C0 but not for I2C2. I performed read/write from board_late_init() function of board/ti/am335x/board.c file.

    I want to use I2C2 from SPL also. In SPL also I2C0 is working but I have no idea about configuring I2C2. here I performed read/write after spl_board_init() call from  board_init_r() function of common/spl/spl.c file.

    Please let me know how to enable I2C2 from SPL and U-boot.

    Regards,

    Rohit

  • 0 in reply to Rohit Kotak
    Intellectual 760 points
    Hi Tsvetolin,

    On U-boot console I am able to see Bus 0 and Bus 1 (as per am33xx.dtsi i2c2):
    SEM3_IOT# i2c bus
    Bus 0: i2c@44e0b000 (active 0)
    Bus 1: i2c@4802a000

    Able to probe all slaves on Bus 0:
    SEM3_IOT# i2c dev 0
    Setting bus to 0
    SEM3_IOT# i2c probe
    Valid chip addresses: 22 34 7C

    By using i2c_set_bus_num(1) function before read/write call, I am able to query read/write operation on I2C1 bus but not able to read/write the data. Following is the error messege:

    i2c_read (addr phase): pads on bus probably not configured (status=0x10)
    i2c_write: pads on bus probably not configured (status=0x10)

    following is the pic mux:
    static struct module_pin_mux i2c2_pin_mux[] = {
    {OFFSET(spi0_sclk), (MODE(2) | RXACTIVE |
    PULLUDEN | SLEWCTRL)}, /* I2C_DATA */
    {OFFSET(spi0_d0), (MODE(2) | RXACTIVE |
    PULLUDEN | SLEWCTRL)}, /* I2C_SCLK */
    {-1},
    };

    Regards,
    Rohit