Linux: How to detect GPIO level or read register value at very beginning of u-boot phase

shawn lin

Other Parts Discussed in Thread: DRA744, DRA746

Tool/software: Linux

Our processor is DRA74X, with 3.02.00.03 SDK version.

We have DRA744 & DRA746, i want to use different DDR configuration for different CPU at u-boot phase. Currently, i have two ideas,

1. Use GPIO, since our custom board have different GPIO value for different CPU, so if i can detect GPIO level, it'll be helpful.

2. Read the CTRL_WKUP_STD_FUSE_DIE_ID_2 register to get base_pn value, which can distinguish between DRA744 & DRA746.

Right now, i try these two ways at board_ti_get_emif_size() function of evm.c at u-boot, but fail. So, how can i know CPU type at very beginning of u-boot phase?

Regards,

Shawn

over 6 years ago

0 Yordan Kamenov over 6 years ago

TI__Mastermind 42515 points

Hi Shawn,

can you share how you try to read CTRL_WKUP_STD_FUSE_DIE_ID_2 and what error/result you get?

Regards,
Yordan

0 shawn lin over 6 years ago in reply to Yordan Kamenov

Genius 3450 points

Hi Yordan,

I use below method, but fail. Any suggestion?

uint8_t id=0;
uint32_t base_pn;

base_pn = readl(0x4ae0c20c);
id = ((base_pn>>24) & 0x0f);

0 Yordan Kamenov over 6 years ago in reply to shawn lin

TI__Mastermind 42515 points

Hi Shawn,

in which function you call this?
Also can you try to read it with:

base_pn = __raw_readl(0x4ae0c20c);

Regards,
Yordan

0 shawn lin over 6 years ago in reply to Yordan Kamenov

Genius 3450 points

Hi Yordan,

Yordan Kamenov said:
in which function you call this?

At two functions,

1.board_ti_get_emif_size()

2.dram_init_banksize()

Yordan Kamenov said:
Also can you try to read it with:

base_pn = __raw_readl(0x4ae0c20c);

It works, thank you.

Regards,
Shawn

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Linux: How to detect GPIO level or read register value at very beginning of u-boot phase