AM437x McSPI problem

Zafar Iqbal

Other Parts Discussed in Thread: AM4372

Hi,

I am going to connect my FPGA from the SPI4 of AM437x, to enable the SPI4 I have made the following changes in the device tree.

spi4_pins: pinmux_spi4_pins {
                pinctrl-single,pins = <
                        0x250 (PIN_OUTPUT | MUX_MODE0) /* spi4_sclk.spi4_sclk */
                        0x254 (PIN_INPUT    | MUX_MODE0) /* spi4_d0.spi4_d0 */
                        0x258 (PIN_OUTPUT | MUX_MODE0) /* spi4_d1.spi4_d1 */
                        0x25C (PIN_OUTPUT | MUX_MODE0) /* spi4_cs0.spi4_cs0 */

and

&spi4 {
    pinctrl-0 = <&spi4_pins>;
    status = "okay";
    pinctrl-names = "default";
    spidev@4 {
        compatible = "rohm,dh2228fv";
        /*compatible = "linux, spidev";*/
        spi-max-frequency = <24000000>;
        reg = <0>;
    };
};

also, I enabled the McSPI driver for OMAP in the kernel configuration,

and enabled User mode SPI device driver support

after this I compiled the kernel and device tree and updated the sd card image and now I can see the spidev2.0 in the /dev.

Now I shorted the pin 65 and pin 63 which is data in and data out of the SPI4 to test the driver.

Now I am sendend the data to the driver but still not able to get any data back.

Please suggest what is the problem here.

Thank you.

Regards,

Zafar

over 9 years ago

0 Biser Gatchev-XID over 9 years ago

TI__Guru**** 393215 points

Hi,

You must change: 0x250 (PIN_OUTPUT | MUX_MODE0) /* spi4_sclk.spi4_sclk */
To: 0x250 (PIN_INPUT | MUX_MODE0) /* spi4_sclk.spi4_sclk */

See Note 1 below Table 26-4 in the AM437x TRM Rev. D for details.

0 Zafar Iqbal over 9 years ago in reply to Biser Gatchev-XID

Prodigy 150 points

Hi,

I have changed the 0x250 (PIN_OUTPUT | MUX_MODE0) to 0x250 (PIN_INTPUT | MUX_MODE0) now but still it is not working, I connected the pin 65 to 63( D1 to D0 ) and sending the data and receiving the same, but I am not able to get it. Is the mode is correct.

Thanks

Regards
Zafar

0 Biser Gatchev-XID over 9 years ago in reply to Zafar Iqbal

TI__Guru**** 393215 points

You seem to be missing the pinmux entry in your &spi4 node. See this wiki: processors.wiki.ti.com/.../Linux_Core_SPI_User's_Guide

0 Zafar Iqbal over 9 years ago in reply to Biser Gatchev-XID

Prodigy 150 points

Hi,

Thanks for your suggestion, Now I am able to use the SPI driver, I am using SPI4 since SPI4 support cs0 and cs1, I wanted to make use of cs1 also so that I can communicate with the other device also, using the same bus.

Please suggest what changes need to be done in the following device tree

spi4_pins: pinmux_spi4_pins {
pinctrl-single,pins = <
0x250 (PIN_OUTPUT | MUX_MODE0) /* spi4_sclk.spi4_sclk */
0x254 (PIN_INPUT | MUX_MODE0) /* spi4_d0.spi4_d0 */
0x258 (PIN_OUTPUT | MUX_MODE0) /* spi4_d1.spi4_d1 */
0x25C (PIN_OUTPUT | MUX_MODE0) /* spi4_cs0.spi4_cs0 */

and

&spi4 {
pinctrl-0 = <&spi4_pins>;
status = "okay";
pinctrl-names = "default";
spidev@4 {
compatible = "rohm,dh2228fv";
spi-max-frequency = <24000000>;
reg = <0>;
};
};

0 Biser Gatchev-XID over 9 years ago in reply to Zafar Iqbal

TI__Guru**** 393215 points

As long as you do not enable the input for SP_SCLK, the receive channel of the McSPI will not work, check Note 1 below Table 26-4 in the AM437x TRM Rev. E for details.

0 Zafar Iqbal over 9 years ago in reply to Biser Gatchev-XID

Prodigy 150 points

Hi,

I made following changes:

spi4_pins: pinmux_spi4_pins {
pinctrl-single,pins = <
0x250 (PIN_INPUT | MUX_MODE0) /* spi4_sclk.spi4_sclk */
0x254 (PIN_INPUT | MUX_MODE0) /* spi4_d0.spi4_d0 */
0x258 (PIN_OUTPUT | MUX_MODE0) /* spi4_d1.spi4_d1 */
0x25C (PIN_OUTPUT | MUX_MODE0) /* spi4_cs0.spi4_cs0 */

and

&spi4 {
pinctrl-0 = <&spi4_pins>;
status = "okay";
pinctrl-names = "default";
spidev@4 {
compatible = "rohm,dh2228fv";
spi-max-frequency = <24000000>;
reg = <0>;
};
};

Now I wanted to connect two devices from the SPI4 ( two different section in FPGA ) hence except the chip select all line D0, D1 and SCLK will remain same, So please suggest what changes I need to add in the device tree so that I can make use of the cs1 ( of SPI4 ) as well. presently only CS0 is used.

Thank you

Regards,

Zafar

0 Yordan Kovachev over 9 years ago in reply to Zafar Iqbal

TI__Guru**** 161600 points

Hi Zafar,

Zafar Iqbal said:
please suggest what changes I need to add in the device tree so that I can make use of the cs1 ( of SPI4 ) as well. presently only CS0 is used.

Try adding ti,spi-num-cs = <number_of_chip_selects>; in spi4: spi@48345000 in am4372.dtsi

Then in your dts try modifying the &spi4 like:
&spi4 {

pinctrl-names = "default";
pinctrl-0 = <&spi4_pins>;
status = "okay";
spidev@4 {
compatible = "rohm,dh2228fv";
spi-max-frequency = <24000000>;
reg = <0>; ==>CS0
};

spidev1@4 {

compatible = "rohm,dh2228fv";
spi-max-frequency = <24000000>;
reg = <1>; ==> CS1
};

};

Hope this helps.

Best Regards,
Yordan

0 Zafar Iqbal over 9 years ago in reply to Yordan Kovachev

Prodigy 150 points

Hi Yordan,

Thanks a lot.

This is working for me now.
Just one last question will this driver by default will be in duplex mode or I need to add duplex =<1> in the device tree to make it in the duplex mode.

Thank you.

Regards,
Zafar

0 Yordan Kovachev over 9 years ago in reply to Zafar Iqbal

TI__Guru**** 161600 points

Hi Zafar,

I am not sure that the spi.c supports full duplex mode. Have a look at the driver: drivers/spi/spi.c, you will see that it only mentions SPI_MASTER_HALF_DUPLEX.

Best Regards,
Yordan

0 Zafar Iqbal over 9 years ago in reply to Yordan Kovachev

Prodigy 150 points

Hi Yordan,

Thanks a lot for your support. I worked yesterday for sometime. I verified the same what you suggested, but those are condition, I looked into the spidev.c file also and found that it supports full duplex also. Now I am able to communicate in the full duplex mode also.

Thanks a lot to help me to make my device up and running.

regards,
Zafar

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AM437x McSPI problem