working kernel version - 2.6.20 patched at91
board - at91sam9260-ek

I'm going to develop the linux application which use the master mode SPI in at91sam9260. The kernel supply the SPI driver.(atmel_spi.c) But I don't know to use this driver in linux. Can I receive the sample application to use the SPI device driver?

I'm novice for Linux. former times, I develped the WinCE product.
And Linux program isn't a familiar job to me.

I found the 'spi-summary document in linux/Documentation/spi folder. Atfer I read this, I guess taht the atmel_spi.c is related the controller driver. And spi.c is Protocol drivers. Is it right?

I guess that the code modify the ek_spi_device structure in board-9260ek.c to customize SPI driver for my project.

But, as before, I don't know how to using the SPI driver in application.

I find the below code in drivers/char/at91_spidev.c

static struct file_operations spidev_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.read = spidev_rd_wr,
.write = (int (*) (struct file *file, const char *buf, size_t count, loff_t *offset))spidev_rd_wr,
.ioctl = spidev_ioctl,
.open = spidev_open,
.release = spidev_close,
};


So, If I write a below code in application, is it right?

file = open("/dev/module name", attribute);
open(file, ~);

I'm sorry for poor english.

Hi there

The SPI is a bridge device that connects other devices to the processor/system bus. There should be no need to access the SPI from an application. Device drivers would use the SPI, since I/O should be done in kernel space.

Dataflash is the only device on the at91sam920ek connected to SPI. Try taking a look at drivers/mtd/devices/at91_dataflash.c.

What device are you going to connect to SPI?

Regards

Thanks for your reply.

In my project, The system comprises two block. One is the main which use the AT91SAM9260, other is the sub block which use the atmel2560. And sub block is four board. Each board has the one atmel 2560.

i.e One AT91SAM9260 has to communicate four atmel2560 by SPI.

And I think to modify below code. (modalias, chip_select, bus_num)
I am planning to use the SPI1 to connect the slaves.

static struct spi_board_info ek_spi_devices[] = {
//#if !defined(CONFIG_MMC_AT91)
{ /* DataFlash chip */
.modalias = "mtd_dataflash",
.chip_select = 1,
.max_speed_hz = 15 * 1000 * 1000,
.bus_num = 0,
},
//#if defined(CONFIG_MTD_AT91_DATAFLASH_CARD)
{ /* DataFlash card */
.modalias = "mtd_dataflash",
.chip_select = 0,
.max_speed_hz = 15 * 1000 * 1000,
.bus_num = 0,
},
//#endif
//#endif
//#if defined(CONFIG_SND_AT73C213) || defined
//(CONFIG_SND_AT73C213_MODULE)
{ /* AT73C213 DAC */
.modalias = "at73c213",
.chip_select = 0,
.max_speed_hz = 10 * 1000 * 1000,
.bus_num = 1,
},
//#endif

As like above mentioned, I don't know how to program the application in user mode. (and now reading "Beginning Linux Programming 2nd" printed by WROX - chapter 3. ). ask advice of a application.

I'm very happy for appending reply.

Hi there

Okay, so you're going to use SPI as an interprocessor communications link.

Unless I'm missing something, fooling around with the existing atmel_spi.c driver is not reasonable. And as currently written, it's not a user accessible device; it has no major/minor numbers and it's not in /dev. So you cannot open, read or write it from an application program.

From the application point-of-view, you want to be able to access the slave processors. So create "devices" for each connected slave. The pseudo-device driver for each slave processor would resemble a combination of the dataflash and a com port. This driver would perform the actual SPI requests using atmel_spi.c just like the at91_dataflash.c driver does. But this driver would have major/minor numbers and open/read/write/ioctl/close operations.

Your application would open each slave device, and perform reads and writes to the slave device. The application should deal with the logical end of the SPI link. Let the device drivers handle all the intermediate SPI handshaking.

Just my $.02.

Regards

hum...I understand what you means. Suddenly, I felt this job very difficult.

Again, Thanks for your replying

I know that kernel 2.6.22 support spi character device driver. That is spidev.c file. (this file omitted the kernel 2.6.20)

The sample code and description is supplied in spidev kernel documentation.

I'm received the above information from Atmel.