Access SPI connected device from u-boot for Tx2i

walter.chow · April 30, 2020, 1:24am

Dear Nvidia team,

Is it possible to access spi connected device from u-boot for Tx2i?
Our customized board has a nvram connected to spi for Tx2i. There is no problem to operate this spi connected nvram from kernel space. However, I am unable to access the same nvram from u-boot using either “sf probe” or “sspi”, and the following is the reported error:

Invalid bus 0 (err=-19)
Failed to initialize SPI flash at 0:0 (error -19)

Any suggestion or pointers how to access the nvram from u-boot would be appreciated.
Thanks.

Walter

ShaneCCC · May 5, 2020, 2:11am

Have a check if below can help.

github.com

siemens/u-boot/blob/master/doc/driver-model/spi-howto.txt

How to port a SPI driver to driver model
========================================

Here is a rough step-by-step guide. It is based around converting the
exynos SPI driver to driver model (DM) and the example code is based
around U-Boot v2014.10-rc2 (commit be9f643). This has been updated for
v2015.04.

It is quite long since it includes actual code examples.

Before driver model, SPI drivers have their own private structure which
contains 'struct spi_slave'. With driver model, 'struct spi_slave' still
exists, but now it is 'per-child data' for the SPI bus. Each child of the
SPI bus is a SPI slave. The information that was stored in the
driver-specific slave structure can now be port in private data for the
SPI bus.

For example, struct tegra_spi_slave looks like this:

struct tegra_spi_slave {

This file has been truncated. show original

walter.chow · May 6, 2020, 1:16am

Hi,

Is there any spi driver currently available at u-boot space for TX2i without the need to port?
If not, I have couple more questions:

For porting a spi driver to driver model per spi-howto.txt , which driver should be based on? u-boot source has tegra114_spi and tegra210_qspi. Are these the right driver to base on? If not, what driver should be used for porting?
Is there a need to update the device tree to enable the access? If yes, can you provide information how to modify it like which file, and how does the entry looks like?
Is there a need to configure the pins? If yes, can you provide information how to configure it?

Thanks.

Walter

ShaneCCC · May 7, 2020, 2:44am

The tegra114_spi driver in U-Boot should be applicable to TX1, TX2, Nano, etc., . It’s not currently in the build for p2771 (aka TX2), so you need to add it to the defconfig for TX2 (p2771-0000-500_defconfig) as CONFIG_TEGRA114_SPI=y and rebuild U-Boot.

For the pin configure you may need to modify the cfg file.
https://elinux.org/Jetson/TX2_SPI#Modifying_the_Pinmux_Configuration

walter.chow · May 7, 2020, 6:59pm

Hi,

There is a compilation error after adding CONFIG_TEGRA114_SPI, and the error is below:

drivers/spi/tegra114_spi.c:12:10: fatal error: asm/arch/clock.h: No such file or directory
| #include <asm/arch/clock.h>
| ^~~~~~~~~~~~~~~~~~

Can you advise how to resolve the error? Thanks.

Walter

TWarren · May 21, 2020, 3:15pm

Walter, please update when you get a chance, I know thru our email conversations that you’ve made significant progress getting the tegra114_spi.c driver to work on TX2, and it might help others to see your changes here.

Thanks,

Tom

walter.chow · June 2, 2020, 5:10pm

Enabling spi device access involves:

Patching tegra186.dtsi and tegra186-p2771-0000.dtsi by adding the device entry.
There is a need to patch tegra114_spi driver in U-Boot to use tegra186 clock which is using driver model besides adding CONFIG_TEGRA114_SPI.
The compilation problem can be resolved by copying clock.h and clock-tables.h from 210 to 186 with update accordingly.

nadeemm · October 18, 2021, 6:18pm