DM385: Trouble with omap2_mcspi driver on linux

Eli Balta

Intellectual 935 points

Other Parts Discussed in Thread: DM385

I need to write a protocol driver for an SPI chip we are using in our application.

I have followed the instructions in those two guides:

http://www.jumpnowtek.com/?option=com_content&view=article&id=57&Itemid=62

http://processors.wiki.ti.com/index.php/TI81XX_PSP_McSPI_Driver_User_Guide

After muxing all the pins to their SPI functions in u-boot, and enabling SPI clock from uboot (CM_ALWON_SPI_CLKCTRL = 0x2), and adding the following code to the board file in the kernel:

struct spi_board_info __initdata dm385_spi_slave_info[] = {
{
.modalias = "an41919a",
.irq = -1,
.max_speed_hz = 10 * 1000 * 1000,
.bus_num = 1,
.chip_select = 0,
.mode = SPI_MODE_3 | SPI_CS_HIGH,
},

};

I can see that once omap2_mcspi.ko is loaded, it shows that it configured a new slave device at bus 1, cs 0, with all the above parameters, and once I load my an41919a.ko module, the probe callback function gets called.

But when I try to use an spi_write() command, I get a return value of 0, indicating no error, but no actual signals can be seen on a logic analyzer looking at the SPI wires.

From looking at omap2_mcspi.c code, it seems like the register configurations are different from what the DM385 TRM mentions for the SPI module.

Is the omap2_mcspi.c compatible with DM385? If yes, what else could I be missing? I have tried playing around with the pull down/up settings in the pinmux of the SPI bus without any results.

over 11 years ago

0 Eli Balta over 11 years ago

Intellectual 935 points

I've done some further debugging regarding the issue.

It seems that the memory addresses for the SPI registers are configured correctly on kernel startup.

My device is connected to SPI[1] bus on the board.

However, when using the correct config (bus_num=2 as opposed to using bus_num=1):

struct spi_board_info __initdata dm385_spi_slave_info[] = {
	{
	.modalias = "an41919a",
	.irq = -1,
	.max_speed_hz = 10 * 1000 * 1000,
	.bus_num = 2,
	.chip_select = 0,
	.mode = SPI_MODE_3 | SPI_CS_HIGH,
	},
};

the omap2_mcspi_probe() does not complete, and fails with an ENODEV error during the following loop:

	for (i = 0; i < num_chipselect; i++) {
 r = platform_get_resource(pdev, IORESOURCE_DMA, 0); 		if (r == NULL) {
				status = -ENODEV;
				goto err1;
			}
		mcspi->dma_channels[i].dma_tx_sync_dev = r->start;
		mcspi->dma_channels[i].dma_tx_channel = -1;
		//printk(KERN_INFO"allocated tx channel:%d\n",r->start);

 r = platform_get_resource(pdev, IORESOURCE_DMA, 1); 		if (r == NULL) {
				status = -ENODEV;
				goto err1;
			}
		//printk(KERN_INFO"allocated rx channel:%d\n",r->start);
		mcspi->dma_channels[i].dma_rx_sync_dev = r->start;
		mcspi->dma_channels[i].dma_rx_channel = -1;
	}

Only when using bus_num=1 this function completes successfuly and a new SPI slave is registered without problems.

Can anyone help me with this?

0 Eli Balta over 11 years ago in reply to Eli Balta

Intellectual 935 points

It seems that the version of omap2_mcspi.c that comes with IPNC_RDK 3.5 is problematic and causes DMA allocation errors for spi bus_num > 1

I have used the following version instead:

http://ubuntu.wikimedia.org/git/ubuntu-jaunty/drivers/spi/omap2_mcspi.c

Now I am successfully able to initialize bus 2, and I can see the CS and CLK changing on a logic analyzer whenever I initiate a transfer.

I am still not able to see any data on the MOSI and MISO channels.

I've noticed that the original driver is using D[1] to receive instead of D[0] and changed that in the new driver but that didn't solve the problem.

After changing the D[1] and D[0] Tx/Rx configurations in the driver for the appropriate CONFIG_MACH_TYPE, I am able to send SPI data on the MOSI line.

0 KALPESH PANCHAL over 10 years ago in reply to Eli Balta

Intellectual 265 points

Hi Eli Balta,

We are also facing same issue in IPNC RDK 3.5 for DM385:

McSpi works for "bus_num = 1" only and creates "/dev/spidev1.1 "

but it doesn’t creating spidev2.1 for "bus_num = 2"

The link provided above is not available now.

struct spi_board_info __initdata dm385_spi_slave_info[] = {
    {
        .modalias   = "spidev",
        .irq        = -1,
        .max_speed_hz   = 75000000,
        .bus_num    = 1,
        .chip_select    = 1,
        .mode = SPI_MODE_0,
    },
    {
        .modalias   = "spidev",
        .irq        = -1,
        .max_speed_hz   = 75000000,
        .bus_num    = 2,
        .chip_select    = 1,
        .mode = SPI_MODE_0,
    }
};
==================================

Error occurs in "for loop" described above.

Any help will be very much appreciated,

Thanks in advance

Kalpesh

Processors

Processors forum

DM385: Trouble with omap2_mcspi driver on linux