Linux/AM3352: NAND bus width detection

Balaji Srinivas

Part Number: AM3352

Tool/software: Linux

We're using u-boot v2013.07 and Kernel v4.4 on our custom boards and we're planning to upgrade custom boards with NAND flash from 8bit to 16bit. We are wondering if there is any run-time code support to detect whether the device attached is an 8-bit or 16-bit flash part. I've following questions,

Is there anyway we can detect attached NAND is 8bit vs 16bit in u-boot during runtime without using SYSBOOT options or any external methods?
If we detect correct flash part in u-boot then, is there way we can tell to kernel to select correct address bus width (and any other required configure options to select between 8bit vs 16bit) through kernel parameters from bootloader?

over 7 years ago

0 Biser Gatchev-XID over 7 years ago

TI__Guru**** 393215 points

Hi,

Will you boot from NAND, or use it only for storage?

0 Balaji Srinivas over 7 years ago in reply to Biser Gatchev-XID

Prodigy 90 points

Yep, our devices boots from NAND flash. Below is the possible method that we've been thinking,

Based on sysboot or product id registers we can load 8 bit vs 16 bit configuration in boot-loader but we're not quite how can we support same in Kernel with single image?

Is there are alternate methods to support both 8bit and 16bit NAND flash in single u-boot and Kernel images?

0 Biser Gatchev-XID over 7 years ago in reply to Balaji Srinivas

TI__Guru**** 393215 points

The AM335x ROM code detects NAND bus width automatically and configures the GPMC interface accordingly. See section 26.1.8.4 of the AM335x TRM Rev. P for details.

0 Balaji Srinivas over 7 years ago in reply to Biser Gatchev-XID

Prodigy 90 points

Thanks for pointing to right place for NAND Initialization.

In GPMC Initialization section under 26.1.8.4.2 Initialization and Detection section,
It mentioned that "the data bus width is initially set to 16 bits; and changed to 8 bits if needed after device parameters determination."

So is there similar support in SPL/U-boot?

Apparently it looks like we've to explicitly enable the corresponding defines (GPMC_NAND_ECC_LP_X8_LAYOUT & GPMC_NAND_ECC_LP_X16_LAYOUT for large page) to select 8 bit vs 16 bit in omap_gpmc.h file to configure NAND in u-boot. Is this correct or is there patch or code support similar to ROM code initialization?

What about Kernel NAND initialization?
Say if we define 16 bit NAND configuration in dts file (like bus width, gpmc pin mux etc) and so does Kernel automatically detects the correct NAND chip and configures the GPMC interface accordingly?

Thanks
Balaji

0 Steve Kipisz over 7 years ago in reply to Balaji Srinivas

TI__Genius 15510 points

Which SDK are you using? That is a very old u-boot.

Steve K.

0 Balaji Srinivas over 7 years ago in reply to Steve Kipisz

Prodigy 90 points

Yep, currently we're using very old version of u-boot - 2013.07 and we've just started to upgrade our systems to use u-boot-2017.01.

Is there any patch or support available on u-boot-2017.01 to auto detect NAND type (8 bit vs 16 bit) and auto configure GPMC and also with Kernel v4.4?

0 Steve Kipisz over 7 years ago in reply to Balaji Srinivas

TI__Genius 15510 points

Hi Balaji,
I don't know of any patches. I'll look at the boot ROM code and see how it is done in there.

Steve K.

0 Steve Kipisz over 7 years ago in reply to Steve Kipisz

TI__Genius 15510 points

The boot ROM code does exactly what the TRM says. Sorry I can't post any of it since it is TI internal. You should be able to write a routine to do the detection and then replace where bus-width is being set from device tree with a call to your routine.

Steve K.

Processors

Processors forum

Linux/AM3352: NAND bus width detection