iMX8QXP SPI supported modes

[VijayAnnamalaisamy]

Hi NXP team,

I am working on iMX8QXP SPI. I need to know the supported modes for SPI in iMX8QXP. I understand from the manual that it supports both master and slave mode. So I am using spidev to communicate with the SPI interface. When I tried to set the 3-wire mode(which is half-duplex), I was not able to set it. Please find below the test code used and the output

=========================SPI Test Code BEGIN==============================

#include <fcntl.h>
#include <sys/ioctl.h>

int main(int argc, char *argv[])
{
int fd;
int ret = 0;
char mode;

fd = open("/dev/spidev0.0", O_RDWR);

if (fd >= 0)
{
/* write mode */
mode = SPI_MODE_0;
ret = ioctl(fd,SPI_IOC_WR_MODE,&mode);
if (ret == -1)
perror("mode0:");

/* read mode */
ioctl(fd,SPI_IOC_RD_MODE,&mode);
printf("mode0 = %u\n",mode);

/* write mode */
mode = SPI_MODE_1;
ret = ioctl(fd,SPI_IOC_WR_MODE,&mode);
if (ret == -1)
perror("mode1:");

/* read mode */
ioctl(fd,SPI_IOC_RD_MODE,&mode);
printf("mode1 = %u\n",mode);

/* write mode */
mode = SPI_MODE_2;
ret = ioctl(fd,SPI_IOC_WR_MODE,&mode);
if (ret == -1)
perror("mode2:");

/* read mode */
ioctl(fd,SPI_IOC_RD_MODE,&mode);
printf("mode2 = %u\n",mode);

/* write mode */
mode = SPI_MODE_3;
ret = ioctl(fd,SPI_IOC_WR_MODE,&mode);
if (ret == -1)
perror("mode3:");

/* read mode */
ioctl(fd,SPI_IOC_RD_MODE,&mode);
printf("mode3 = %u\n",mode);

/* write mode */
mode = SPI_3WIRE;
ret = ioctl(fd,SPI_IOC_WR_MODE,&mode);
if (ret == -1)
perror("mode-3wire:");

/* read mode */
ioctl(fd,SPI_IOC_RD_MODE,&mode);
printf("mode16 = %u\n",mode);
if (ret == -1)
perror("mode3:");

/* read mode */
ioctl(fd,SPI_IOC_RD_MODE,&mode);
printf("mode3 = %u\n",mode);

/* write mode */
mode = SPI_3WIRE;
ret = ioctl(fd,SPI_IOC_WR_MODE,&mode);
if (ret == -1)
perror("mode-3wire:");

/* read mode */
ioctl(fd,SPI_IOC_RD_MODE,&mode);
printf("mode16 = %u\n",mode);

}

close(fd);

return 0;
}

=========================SPI Test Code ENDS==============================

The output I have got is below which shows that 3-wire(half-duplex) is not supported:

mode0 = 4[ 1162.005031] spidev spi0.0: setup: unsupported mode bits 10

mode1 = 5
mode2 = 6
mode3 = 7
mode-3wire:: Invalid argument
mode16 = 7

Queries:

1. In iMX8 QXP, below modes are supported? Please let me know
   1. Full Duplex Master
   2. Full Duplex Slave
   3. Half Duplex(3-wire) Master
   4. Half Duplex(3-wire) Slave
2. Does any driver configurations need to be done to enable all the above modes?
3. In the above sample code, reading back the SPI modes give 4,5,6 & 7 instead of 0,1,2,3. What is the reason for this?
4. Please share some example or reference codes if any for the SPI

Thank you,

Vijay.

[Zhiming_Liu · Accepted solution]

Hi @VijayAnnamalaisamy 

Here is spi test code in BSP, you can refer that.

https://github.com/nxp-imx/imx-test/blob/lf-5.15.32_2.0.0/test/mxc_spi_test/mxc_spi_test1.c

Please refer driver logic, the mode you set from userspace will be handled in fsl_lpspi_set_cmd function.

static void fsl_lpspi_set_cmd(struct fsl_lpspi_data *fsl_lpspi)
{
	u32 temp = 0;

	temp |= fsl_lpspi->config.bpw - 1;
	temp |= (fsl_lpspi->config.mode & 0x3) << 30;
	temp |= (fsl_lpspi->config.chip_select & 0x3) << 24;
	if (!fsl_lpspi->is_slave) {
		temp |= fsl_lpspi->config.prescale << 27;
		/*
		 * Set TCR_CONT will keep SS asserted after current transfer.
		 * For the first transfer, clear TCR_CONTC to assert SS.
		 * For subsequent transfer, set TCR_CONTC to keep SS asserted.
		 */
		if (!fsl_lpspi->usedma) {
			temp |= TCR_CONT;
			if (fsl_lpspi->is_first_byte)
				temp &= ~TCR_CONTC;
			else
				temp |= TCR_CONTC;
		}
	}
	writel(temp, fsl_lpspi->base + IMX7ULP_TCR);

	dev_dbg(fsl_lpspi->dev, "TCR=0x%x\n", temp);
}

For controller, it doesn't support SPI_3WIRE feature.

controller->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;

For modes, it can support :

1. Full Duplex Master
2. Full Duplex Slave

[mengfei]

你好，我在你们官方网站中看到有关spi设置为slave模式的文章。 https://www.nxp.com.cn/docs/en/application-note/AN13633.pdf 其中在8 Software package description 中有说文档附带了测试程序。但是我只能看到文档看不到测试程序，能不能把文档里的代码给我发一份？

[Zhiming_Liu]

网站上有

i.MX 8M Applications Processor | Arm® Cortex®-A53, Cortex-M4 | 4K display resolution | NXP Semicondu...

[mengfei]

是我说的不够详细吗？ 文档我一直能下载并阅读。我想要的是文档里提到的你们的开发者写的patch及测试例程，文档里说其自己修改了spidev_test.c。

在8 Software package description中其指出该文档还应有几个附属的代码文件，我想要的就是那些测试代码。麻烦您看清我的需求。

[Zhiming_Liu]

在你发问之前瞪大眼睛看看图片上红色的范围是不是你想要的东西。

[VijayAnnamalaisamy]

Thank you @Zhiming_Liu for the support