AM62X-PET-CALC: AM62LX:How do I know what the number of the GPIO set by the AM62X_IOPAD macro is?

Hello,

I'm returning to office today& currently looking into this. Please ping this thread by Thursday if you haven't received a response yet.

Thanks,

Anshu

Hi Anshu：

I opened the file AM62x Datasheet and still didn't find the relationship between the GPIO number and the address offset

https://www.ti.com/lit/pdf/spruiv7 connection I can't open.,Is this a file? Can you send me the file directly?

Thanks

Hi Anshu：

Let's take an example：

AM62X_IOPAD(0x00c, PIN_INPUT, 0) /* (E25) OSPI0_D0 */

1、From this table, GPIO0_4 is used for functional OSPI_DO

2、So where does the 0x00c offset in the code get it? Or rather, viewed

3、And what is the address 0x00F4010 in the form used for?

Thanks

Mingxing

Hello Mingxing,

The two documents I referred to are on the AM625 product page: https://www.ti.com/product/AM625

OSPI0_D0 and OSPI0_D1 are two different pins. These two pins will have different PADCONFIG addresses and GPIOs associated with them.

Every PADCONFIG register has a base address of 0xF4000 and then add an offset for the specific register.

Huang Mingxin said:

And what is the address 0x00F4010 in the form used for?

See 14.2.1.2 Pad Configuration Registers in the AM62x TRM.

Thanks,
Anshu

Hi Anshu：

1.I still can't download the document you said from https://www.ti.com/product/AM625, I don't know if it's a network problem or something else, when I download it, it always can't load.

2.Can you send me the PDF file directly

3.If I want to configure the state of the GPIO in the device tree, then I need to figure out the relationship between the register address and offset and the GPIO number

Thanks

Mingxing

Hi Anshu:

1.I've downloaded the documentation, but I still don't understand how to set the GPIO state

2.You can use OSPI0_D0 (GPIO0_3) as an example to show me how to set GPIO3 to ouput high ？

How to set the parameters of AM62X_IOPAD(pa, val, muxmode)? Especially for the pa parameter, how do I know what value to write? 

3.Why not use the pinctrl mechanism to set the GPIO and use such a cumbersome encapsulation? Is there any merit in this

Thanks

Mingxing

Hello Mingxing,

Huang Mingxin said:

I still don't understand how to set the GPIO state

This is done in userspace with using commands like gpioget and gpioset NOT by pinmuxing: https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1260373/faq-transitioning-the-gpio-userspace-interface-from-sysfs-to-chardev

Huang Mingxin said:

How to set the parameters of AM62X_IOPAD(pa, val, muxmode)?

This is done in the Linux device tree under the main_pmx node. The components meaning I've stated before.

Anshu Madwesh said:

The first parameter is the address of the PAD CONFIGURATION register. The second parameter is the pad direction. The third parameter is the Mux Mode.

Notice the following for 'AM62X_IOPAD(0x008, PIN_INPUT, 7)':

You can see for an LED as an example: git.ti.com/.../k3-am62x-sk-common.dtsi

Huang Mingxin said:

Why not use the pinctrl mechanism to set the GPIO and use such a cumbersome encapsulation?

The alternative is to individually write to each PADCONFIG register that will be used. When there are 75+ pads in use, this is not feasible to write to each registers, one by one. Pinctrl helps take care of this during Linux boot.

Thanks,

Anshu

Hi Anshu：

I seem to understand how to set the state of the GPIO in the device tree, but there are still some small questions I would like to ask：

1. The offset in the device tree is used for the last 3 bits（008） of the register address, so what are the first 5 bits（000F4） of the register address used for?

2. I checked the macro that sets the GPIO state, there are set GPIO to input/output and pullup/pulldown, but I don't seem to see the GPIO set to high and low levels, where is the high and low level of GPIO set?

Thanks

Hello Mingxing,

Huang Mingxin said:

1. The offset in the device tree is used for the last 3 bits（008） of the register address, so what are the first 5 bits（000F4） of the register address used for?

Its just short hand notation. The known base address is 0xF4000 so all that matters is the offset of the register.

Huang Mingxin said:

2. I checked the macro that sets the GPIO state, there are set GPIO to input/output and pullup/pulldown, but I don't seem to see the GPIO set to high and low levels, where is the high and low level of GPIO set?

This PinMuxing does not change the GPIO state. This pinmuxing applies for all peripherals like UART, I2C, MMC, Display etc. not just GPIOs. The PinMuxing only allows the pad to be capable to receiving and transmitting.

The SoC requires the application to drive the state.

Feel free to read a longer discussion in the last post of this E2E: https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1426818/am623-gpio-status-not-updating-in-output-mode/5490248#5490248

Best Regards,

Anshu

Hi Anshu:

What if I want to use code to set a GPIO high when the kernel starts? According to what you said, the device tree can't be set high, so if I want to set high, can I only use the GPIO API(gpiod_line_set_value) to do high?

Thanks

Hello Mingxing,

You would have to do this a U-Boot stage. There is a simple FAQ to follow for setting a GPIO at U-Boot: https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1398803/faq-processor-sdk-am62x-how-to-toggle-gpios-and-leds-from-u-boot-command-prompt

Its also possible to configure from the U-Boot init code, but TI doesn't provide an example of this.

Best Regards,

Anshu

Hi Anshu：

I seem to understand what you mean

1.At the kernel layer, we can't configure it with dtsi to control the high and low levels of the GPIO, only the input and output modes and pullup/pulldowm

2.If you want to control the high and low levels, you can use the command gpio set/toggle/clear in the boot phase

3.As for the registers, I don't understand your strategy too well

4.I tried it myself, and in user space, I can control the high and low levels of GPIO in user space through a series of commands under the sys/class/gpio path

5.I searched the GPIO API (gpio_set_value) under the drivers path and found that it exists, and if you want to set the GPIO state at the kernel layer, you should be able to set it through the gpio_set_value

I don't know if there are any errors in my summary, if there are mistakes, please help point them out

Thanks

Hi Anshu：

Just note that TI cannot provide support for custom code and applications.

--->That's the question I stated, I mean, can we set the GPIO state in the boot phase of the boot code, and if so, can you tell me the location

Thanks

Hello Mingxing,

You can refer to this similar E2E thread: https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1422521/am62a7-configure-gpio-as-input-and-read-gpio-value-from-u-boot-source-code

Best Regards,

Anshu

Hi Anshu:

According to the connection you sent, I summarize the method of setting the GPIO in the boot phase：

1.Set via GPIO commands ，'gpio set <pin>', 'gpio toggle <pin>', 'gpio clear <pin>' 

2.Set the value of the GPIO by running it in the current evm.c file via the API function（gpio_request,gpio_direction_output,gpio_set_value

） in the gpio.h file

Please help to see if this is correct

Thanks