SPI config for AM5728

Srinidhi S

Other Parts Discussed in Thread: AM5728

Hello,

We are trying to configure SPI on a custom board on AM5728 core. We have similar design as that of BeagleBone-X15. We have made the below changes in the device tree to adapt SPI4.

************************************************************************

FILE NAME: am57xx-beagle-x15.dts

aliases {
rtc0 = &mcp_rtc;
rtc1 = &tps659038_rtc;
rtc2 = &rtc;
sound1 = &hdmi;
i2c5 = &i2c5;
spi4 = &mcspi4;
};

mcspi4_pins: pinmux_mcspi4_pins {
pinctrl-single,pins = <
0x3A4 (PIN_INPUT | MUX_MODE0) /* mcspi4_clk */
0x3AC (PIN_INPUT | MUX_MODE0) /* mcspi4_simo */
0x3A8 (PIN_INPUT | MUX_MODE0) /* mcspi4_somi */
0x3B0 (PIN_INPUT | MUX_MODE0) /* mcspi4_cs0 */
>;
};

&mcspi4 {
pinctrl-names = "default";
pinctrl-0 = <&mcspi4_pins>;
status = "okay";
};

************************************************************************

We have enabled the required SPI device driver in the kernel by

Device Drivers  --->
[*] SPI support
 [*] Mcspi Driver for Omap.

Is there anything to be done further? Please suggest.

Best Regards,

Srinidhi S.

over 9 years ago

0 Biser Gatchev-XID over 9 years ago

TI__Guru**** 393215 points

I will forward this to the software team.

0 Yordan Kovachev over 9 years ago

TI__Guru**** 161600 points

Hi,

Check the following thread: e2e.ti.com/.../496527

With the modifications described there, I've successfully enabled spi4 in am57xx beagle-x15.

Best Regards,
Yordan

0 Srinidhi S over 9 years ago in reply to Yordan Kovachev

Intellectual 875 points

Thanks for the reply. I see the following response to devmemcheck. Am not sure if this is correct.

./devmem2 0x4A009808
/dev/mem opened.
Memory mapped at address 0xb6f84000.
Value at address 0x4A009808 (0xb6f84808): 0x30000

And the spi_dev_test.c output yields:
spi mode: 0x0
bits per word: 8
max speed: 500000 Hz (500 KHz)
RX | 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 | ................................

Best Regards,
Srinidhi S.

0 Yordan Kovachev over 9 years ago in reply to Srinidhi S

TI__Guru**** 161600 points

Hi,

Yes, output should be similar.
Have you probed the spi pins with an oscilloscope to see if they are toggling?

Best Regards,
Yordan

0 Srinidhi S over 9 years ago in reply to Yordan Kovachev

Intellectual 875 points

Hello,
There seems to be no toggling in the pins!
My modified device tree is as below:

*********************************************************
aliases {
spi4 = &mcspi4;
};

mcspi4_pins: mcspi4_pins {
pinctrl-single,pins = <
0x160 (PIN_INPUT_PULLUP | MUX_MODE8) /* mcspi4_clk */
0x068 (PIN_INPUT_PULLUP | MUX_MODE8) /* mcspi4_miso */
0x348 (PIN_OUTPUT_PULLUP | MUX_MODE2) /* mcspi4_mosi */
0x06C (PIN_OUTPUT_PULLUP | MUX_MODE8) /* mcspi4_cs0 */
>;
};

&mcspi4 {
status = "okay";
pinctrl-names = "default";
pinctrl-0 = <&mcspi4_pins>;
ti,pindir-d0-out-d1-in=<1>;
spidev@4 {
spi-max-frequency = <8000000>;
reg = <0>;
compatible = "rohm,dh2228fv";
};
};
*********************************************************
cat /sys/kernel/debug/pinctrl/4a003400.pinmux/pingroups
group: mcspi4_pins
pin 88 (4a003560.0)
pin 26 (4a003468.0)
pin 210 (4a003748.0)
pin 27 (4a00346c.0)

Best Regards,
Srinidhi S.

0 Srinidhi S over 9 years ago in reply to Srinidhi S

Intellectual 875 points

Please respond to this thread.

Best Regards,
Srinidhi S.

0 Yordan Kovachev over 9 years ago in reply to Srinidhi S

TI__Guru**** 161600 points

Hi,

I measured again on my am572x beagle x15, using the exact same modifications as in my previous post. Measured pins are:

P17_ 37 -> spi4_clk

P17_35 -> spi4_d1

P17_6 -> spi4_cs0

Here are the oscilloscope diagrams:

I executed echo "DEADBEEF" > /dev/spidev1.0.

Have you checked in your sources that the muxed pins are NOT used by any other module? Have you enabled spidev driver (CONFIG_SPI_SPIDEV=y)?

Best Regards,
Yordan

0 Srinidhi S over 9 years ago in reply to Yordan Kovachev

Intellectual 875 points

My pins are not multiplexed anywhere. We have brought the pins directly from the core without any pullup/pulldown resistors anywhere.

But still i don't see any activities! Am surprised.

Best Regards,
Srinidhi S.

0 Yordan Kovachev over 9 years ago in reply to Srinidhi S

TI__Guru**** 161600 points

Hi,

"We have brought the pins directly from the core without any pullup/pulldown resistors anywhere. "

I am a little confused here.. you need to do a proper pinmux settings from kernel space (not user spce) with pulls enabled, if you want your spi to work properly.

Best Regards,
Yordan

0 Srinidhi S over 9 years ago in reply to Yordan Kovachev

Intellectual 875 points

I mean, in our schematics, we have not connected any pullup/pulldown resistors to the pins.
Ball G1 -> SPI4 clk;
Ball AB9 -> d1;
N9 -> d0;
p9 -> CS0 are running directly to the connection headers.
Will this cause any problem?

Best Regards,
Srinidhi S.

0 Srinidhi S over 9 years ago in reply to Srinidhi S

Intellectual 875 points

And also, CONFIG_SPI_SPIDEV=y

0 Yordan Kovachev over 9 years ago in reply to Srinidhi S

TI__Guru**** 161600 points

Hi,

Srinidhi S said:
Will this cause any problem?

No, It shouldn't cause problems. Internal pulls should be enough, if you check am572x gp evm schematic, you can see that the pins I use, i.e. mmc_dat4 (muxed as spi4_clk) is connected directly to the expansion header P17_35.

Check your boot log, there may be some error messages, which indicate why your system does not accept the pinmux & spi settings?

Best Regards,
Yordan

0 PRRADDHEP REDDE over 9 years ago in reply to Yordan Kovachev

Intellectual 790 points

Hi yordan,
I have same problem with SPI in my custom board with AM5728 processor.
/dev/spidev1.0 is available but while transferring data the clock is not showing in scope.
my dts file is

&mcspi1 {
pinctrl-names = "default";
pinctrl-0 = <&mcspi1_pins>;
status = "okay";

spidev@0{
compatible = "rohm,dh2228fv";
spi-max-frequency = <48000000>;
reg = <0x0>;
status = "okay";
};

};

Thanks,
PRRADDHEP REDDE

0 Yordan Kovachev over 9 years ago in reply to PRRADDHEP REDDE

TI__Guru**** 161600 points

Have you enabled the spidev driver in menuconfig?
Have you done the correct spi pinmuxing?

Can you probe all the other spi pins: CS0, D0 and D1, to see if you have any activity on them? If yes, then you may have measured on the wrong pin.

Best Regards,
Yordan

0 PRRADDHEP REDDE over 9 years ago in reply to Yordan Kovachev

Intellectual 790 points

Hi Yordan,

In CCS i got CLK and CS0 in scope.

But in Linux kernel my CS0 is high in scope and CLK is low.

When i transfer data in /dev/spidev1.0 (Which is SPI4) even though CLK is always low.

My PinMux in Linux for SPI4:

---------------------------------------

        mcspi4_pins: mcspi4_pins {
                pinctrl-single,pins = <
                        0x160 (PIN_INPUT_PULLUP | MANUAL_MODE | MUX_MODE8) /*vin2a_hsync0.spi4_clk*/
                        0x164 (PIN_INPUT_PULLUP | MANUAL_MODE | MUX_MODE8) /*vin2a_vsync0.spi4_d1*/
                        0x168 (PIN_OUTPUT_PULLUP | MANUAL_MODE | MUX_MODE8) /*vin2a_d0.spi4_d0*/
                        0x350 (PIN_OUTPUT_PULLUP | MANUAL_MODE | MUX_MODE2) /*mcasp5_axr1.spi4_cs0*/
                >;
        };

&mcspi4 {
        pinctrl-names = "default";
        pinctrl-0 = <&mcspi4_pins>;
        status = "okay";

        spidev@0{
                  compatible = "rohm,dh2228fv";
                  spi-max-frequency = <48000000>;
                  reg = <0x0>;
                  status = "okay";
        };

};

My kernal config for SPI:

----------------------------------------

CONFIG_SPI_SPIDEV=y

CONFIG_SPI_OMAP24XX=y

CONFIG_SPI=y
CONFIG_SPI_DEBUG=y
CONFIG_SPI_MASTER=y

In U-boot:

-------------------

In u-boot when i press "sspi" command the system hanged.Can i enable any thing regarding SPI in u-boot

Thanks,

PRRADDHEP REDDE

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SPI config for AM5728