Detect i2c in SPL for AST2600

[黃志偉]

Hello devs,
I’m working on a BMC system using ASPEED AST2600.
We got the u-boot 2019.04 code from BMC provider (AMI).
I’m trying to enable multidtb to support different SKUs of
our boards. The plan is to detect the board id via i2c so that
we can load the corresponding DTB.

I’ve read README.multi-dtb-fit and enabled these configs:
CONFIG_DTB_RESELECT=y
CONFIG_MULTI_DTB_FIT=y
CONFIG_OF_LIBFDT_OVERLAY=y
CONFIG_OF_LIST="ast2600-board1 ast2600-board2"

Then add board_fit_config_name_match like
#ifdef CONFIG_MULTI_DTB_FIT
int board_fit_config_name_match(const char *name)
{
    struct udevice *bus, *dev;
    int ret = uclass_get_device_by_seq(UCLASS_I2C, 2, &bus);
    if (ret) {
        printf("Can’t access I2C2: %d\n", ret);
        return ret;
    }

    ret = dm_i2c_probe(bus, 0xE8, 0, &dev);
    if (ret) {
        printf("Can’t detect id: %d\n", ret);
        return ret;
    }
   if (strcmp(name, "ast2600-board1")
        return -1;
   return 0;
}
#endif

However, it doesn’t work as expected.
uclass_get_device_by_seq failed with errno -19 (No such device).

After further study I guess I have to enable I2C in SPL.
So I added these configs:

CONFIG_SPL_I2C_SUPPORT=y
CONFIG_SPL_BOARD_INIT=y

Add spl_board_init like:
#ifdef CONFIG_SPL_BOARD_INIT
void spl_board_init(void)
{
    struct udevice *bus, *dev;
    int ret = uclass_get_device_by_seq(UCLASS_I2C, 2, &bus);
    if (ret) {
        printf("Can’t access I2C2: %d\n", ret);
    }

    ret = dm_i2c_probe(bus, 0xE8, 0, &dev);
    if (ret) {
        printf("Can’t detect id: %d\n", ret);
    }
}
#endif

I also added these to DTS:

&pinctrl_i2c3_default {
        u-boot,dm-spl;
};

&i2c2 {
        status = "okay";
        pinctrl-names = "default";
        pinctrl-0 = <&pinctrl_i2c3_default>;
        u-boot,dm-spl;
};

However, it still doesn’t work.
I have no idea how to go further.

Please give me some suggestions.
Or is it simply impossible to do that?

Best Regards,
Chih-Wei
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