SPI Linux driver - davinci_spi.c

Joe Z

Intellectual 640 points

Other Parts Discussed in Thread: SYSBIOS

Hello everyone,

I am looking for help on spi driver issue.

I am using OMAPL-138 on LogicPD's (eXperimenter Kit) and work on ARM core with Linux OS, TI's DVSDK.

I find a problem is that this my salve spi device is set to the master' frequency.

On the function davinci_spi_setup_transfer(), there is a line of code

if (!hz)
hz = spi->max_speed_hz;

This 'hz' comes from above line of code

if (t) {
bits_per_word = t->bits_per_word;
hz = t->speed_hz;
}

The 't' is the passed argument, struct spi_transfer *t. which is "0" when a salve spi driver is in transfer operation.

Is anyone can help me on this?

My slave driver is based on spike -

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

and hook on the davinci_spi driver through board-da850-evm.c

Thank you for tips

Joe

over 13 years ago

0 Raja over 13 years ago

TI__Guru* 81335 points

Hi Joe,

Please configure the SPI slave device with "spike" driver as follows. (Please refer "Driver Setup" section of your link)

static struct spi_board_info da850evm_spi_info[] {
{
.modalias = ?,
.max_speed_hz = ?,
.bus_num = ?,
.chips_select = ?,
.mode = ?,
},
{
.modalias = "m25p80",
.platform_data = &da850evm_spiflash_data,
.controller_data = &da850evm_spiflash_cfg,
.mode = SPI_MODE_0,
.max_speed_hz = 30000000,
.bus_num = 1,
.chip_select = 0,

},
};

The m25p80 driver is used to read/write the SPI flash which is connected in SPI Master Interface.

0 Joe Z over 13 years ago in reply to Raja

Intellectual 640 points

Hi Rajasekaran,

I did add on that section as following,

{
.modalias = "spidev",
.controller_data = &da850evm_spike_cfg,
.mode = SPI_MODE_0,
.max_speed_hz = 30000000,
.bus_num = 1,
.chip_select = 2,
},

this code is to hook on the spi1. What else you can think about I should take care of it? Thank you

Joe

0 Raja over 13 years ago in reply to Joe Z

TI__Guru* 81335 points

Hi Joe,

This should be sufficient to hook up a driver for SPI device. Please follow the link section "Driver Setup".

Thanks.

0 Joe Z over 13 years ago in reply to Raja

Intellectual 640 points

Hi Rajasekara,

Would you tell me which "Driver Setup" section you have referred ?

Thanks

Joe

0 Raja over 13 years ago in reply to Joe Z

TI__Guru* 81335 points

Hi Joe,

I was referring to the link which is shared by you in this thread.

Please refer the Linux kernel documentation on "Overview of Linux kernel SPI support" for SPI Slave device.

0 Raja over 13 years ago in reply to Raja

TI__Guru* 81335 points

Hi Joe,

Could you able to configure the SPI Driver successfully?

0 Joe Z over 13 years ago in reply to Raja

Intellectual 640 points

No, I don't get why. I just configure it on master side.

0 Raja over 13 years ago in reply to Joe Z

TI__Guru* 81335 points

Hi Joe,

As per "Overview of Linux kernel SPI support" documentation, the Linux currently only supports the master side of SPI interactions.

Please refer the kernel documentation (Documentation/spi/spi-summary) for more details.

0 Joe Z over 13 years ago in reply to Raja

Intellectual 640 points

I think you misunderstood my question. If these documents will help, I will not ask help here.

0 Raja over 13 years ago in reply to Joe Z

TI__Guru* 81335 points

Joe,

Thanks for the post.

This is the Device forum, in which we will help users to solve the device related issues. We will provide the driver, examples source to validate the device components. To test SPI slave device, I shall provide non-OS/SYSBIOS based SPI driver & example sources. But that will not run on top of Linux.

Suggestion:

You shall modify the Linux SPI driver to support slave as below links.

http://e2e.ti.com/support/embedded/linux/f/354/t/162748.aspx

http://e2e.ti.com/support/embedded/linux/f/354/t/121380.aspx?pi65987=1

(OR)

2.You shall write a character device driver for SPI slave device and shall be loaded as module to the Linux kernel.

Links to SPI Slave Sources:

Please download the BSL from LogicPD, which has the source to configure the SPI slave. (Search for "BSL LogicPD" in google)
SYS BIOS based SPI Slave Source shall be found at: http://software-dl.ti.com/dsps/dsps_public_sw/psp/BIOSPSP/01_30_00_06/index_FDS.html

Please let us know, If the above information is not solving your issue then we will move this post to Linux Forum.

0 Joe Z over 13 years ago in reply to Raja

Intellectual 640 points

HI Rajasekaran,

Thank you for sending out info.

Yep, if you can move my question to Linux Form, It maybe better.

Joe

Processors

Processors forum

SPI Linux driver - davinci_spi.c