UM0851 datasheet(90/245 Pages) STMICROELECTRONICS

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Communication device drivers

UM0851

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Doc ID 16604 Rev 2

struct spi_board_info can be initialized as:

static struct

spi_board_info spi_board_info[] __initdata = {

{

.modalias= "eeprom",

.platform_data= &m25_info,

.controller_data = &m25_hw,

.max_speed_hz= 21000000,/*21MHz*/

.mode = SPI_MODE_3,

.bus_num= SPEAR_SSP0_ID,

.chip_select= 1,

}

Note:

The name provided in modalias should be the same as the slave driver name.

The combination of bus_num and chip_select must be unique. The device will be visible in

the sysfs directory with the name: spi [bus_num].[chip_select].

The controller transmits data on the available frequency, which must be less than or equal to

Max_speed_hz.

Registering the driver

The SPI slave driver must be registered with the SPI framework. This is accomplished by

calling spi_register_driver(&eeprom_driver), where struct slave_driver is a structure which

contains information about the SPI slave driver.

struct spi_driver {

int

(*probe)(struct spi_device *spi);

int

(*remove)(struct spi_device *spi);

void

(*shutdown)(struct spi_device *spi);

int

(*suspend)(struct spi_device *spi, pm_message_t mesg);

int

(*resume)(struct spi_device *spi);

struct device_driverdriver;

};

You may not need to implement all these functions. Like for the EEPROM driver, only few

fields are given:

struct spi_driver eeprom_driver = {

.driver = {

.name

= "eeprom", /* field must contain the same name, which is used while

adding the slave device in spi_board_info structure, using

.modalias name */

.owner

= THIS_MODULE,

.probe

= eeprom_probe,

.remove

= __devexit_p(eeprom_remove),

};

The kind of interface provided to the user applications is slave driver dependent (sysfs, proc,

dev, etc).

The struct spi_device is passed to the slave driver when the probe function of the slave is

called from the SPI framework after the device registration. You must save the structrure in

the slave driver and use it for any communication with the SPI framework. The definition of

this structure is:

struct spi_device {

struct device dev;

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