spi.c File Reference

SPI devices. More...

#include <stddef.h>
#include <errno.h>
#include <unistd.h>
#include <ipxe/spi.h>

Go to the source code of this file.

Functions
	FILE_LICENCE (GPL2_OR_LATER_OR_UBDL)
static unsigned int	spi_command (unsigned int command, unsigned int address, int munge_address)
	Munge SPI device address into command.
static int	spi_wait (struct spi_device *device)
	Wait for SPI device to complete operation.
int	spi_read (struct nvs_device *nvs, unsigned int address, void *data, size_t len)
	Read data from SPI device.
int	spi_write (struct nvs_device *nvs, unsigned int address, const void *data, size_t len)
	Write data to SPI device.

Detailed Description

SPI devices.

Definition in file spi.c.

Function Documentation

FILE_LICENCE()

FILE_LICENCE

(

GPL2_OR_LATER_OR_UBDL

)

spi_command()

unsigned int spi_command ( unsigned int command, unsigned int address, int munge_address )

inlinestatic

Munge SPI device address into command.

Parameters

command	SPI command
address	Address
munge_address	Device requires address munging

Return values

command

Actual SPI command to use

Some devices with 9-bit addresses (e.g. AT25040A EEPROM) use bit 3 of the command byte as address bit A8, rather than having a two-byte address. This function takes care of generating the appropriate command.

Definition at line 50 of file spi.c.

                                                             {
        return ( command | ( ( ( address >> 8 ) & munge_address ) << 3 ) );
}

References address.

Referenced by spi_read(), and spi_write().

spi_wait()

int spi_wait ( struct spi_device * device )

static

Wait for SPI device to complete operation.

Parameters

device

SPI device

Return values

rc	Return status code

Definition at line 62 of file spi.c.

                                                  {
        struct spi_bus *bus = device->bus;
        uint8_t status;
        int i;
        int rc;
 
        for ( i = 0 ; i < 50 ; i++ ) {
                udelay ( 20 );
                if ( ( rc = bus->rw ( bus, device, SPI_RDSR, -1, NULL,
                                      &status, sizeof ( status ) ) ) != 0 )
                        return rc;
                if ( ! ( status & SPI_STATUS_NRDY ) )
                        return 0;
        }
        DBG ( "SPI %p timed out\n", device );
        return -ETIMEDOUT;
}

References bus, DBG, ETIMEDOUT, NULL, rc, SPI_RDSR, SPI_STATUS_NRDY, status, and udelay().

Referenced by spi_write().

spi_read()

int spi_read	(	struct nvs_device *	nvs,
		unsigned int	address,
		void *	data,
		size_t	len )

Read data from SPI device.

Parameters

nvs	NVS device
address	Address from which to read
data	Data buffer
len	Length of data buffer

Return values

rc	Return status code

Definition at line 89 of file spi.c.

                                        {
        struct spi_device *device = nvs_to_spi ( nvs );
        struct spi_bus *bus = device->bus;
        unsigned int command = spi_command ( SPI_READ, address,
                                             device->munge_address );
        int rc;
 
        DBG ( "SPI %p reading %zd bytes from %#04x\n", device, len, address );
        if ( ( rc = bus->rw ( bus, device, command, address,
                              NULL, data, len ) ) != 0 ) {
                DBG ( "SPI %p failed to read data from device\n", device );
                return rc;
        }
 
        return 0;
}

References address, bus, data, DBG, len, NULL, spi_device::nvs, rc, spi_command(), and SPI_READ.

spi_write()

int spi_write	(	struct nvs_device *	nvs,
		unsigned int	address,
		const void *	data,
		size_t	len )

Write data to SPI device.

Parameters

nvs	NVS device
address	Address from which to read
data	Data buffer
len	Length of data buffer

Return values

rc	Return status code

Definition at line 116 of file spi.c.

                                               {
        struct spi_device *device = nvs_to_spi ( nvs );
        struct spi_bus *bus = device->bus;
        unsigned int command = spi_command ( SPI_WRITE, address,
                                             device->munge_address );
        int rc;
 
        DBG ( "SPI %p writing %zd bytes to %#04x\n", device, len, address );
 
        if ( ( rc = bus->rw ( bus, device, SPI_WREN, -1,
                              NULL, NULL, 0 ) ) != 0 ) {
                DBG ( "SPI %p failed to write-enable device\n", device );
                return rc;
        }
 
        if ( ( rc = bus->rw ( bus, device, command, address,
                              data, NULL, len ) ) != 0 ) {
                DBG ( "SPI %p failed to write data to device\n", device );
                return rc;
        }
        
        if ( ( rc = spi_wait ( device ) ) != 0 ) {
                DBG ( "SPI %p failed to complete write operation\n", device );
                return rc;
        }
 
        return 0;
}

References address, bus, data, DBG, len, NULL, spi_device::nvs, rc, spi_command(), spi_wait(), SPI_WREN, and SPI_WRITE.