spi.c File Reference

SPI devices. More...

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

Go to the source code of this file.

Functions
	FILE_LICENCE (GPL2_OR_LATER)
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

(

GPL2_OR_LATER

)

static unsigned int spi_command	(	unsigned int	command,
		unsigned int	address,
		int	munge_address
	)			[inline, static]

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 45 of file spi.c.

Referenced by spi_read(), and spi_write().

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

static 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 57 of file spi.c.

References spi_device::bus, DBG, ETIMEDOUT, NULL, spi_bus::rw, SPI_RDSR, SPI_STATUS_NRDY, and udelay().

Referenced by spi_write().

                                                  {
        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;
}

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 84 of file spi.c.

References spi_device::bus, DBG, spi_device::munge_address, NULL, spi_bus::rw, spi_command(), and SPI_READ.

                                        {
        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;
}

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 111 of file spi.c.

References spi_device::bus, DBG, spi_device::munge_address, NULL, spi_bus::rw, spi_command(), spi_wait(), SPI_WREN, and SPI_WRITE.

                                               {
        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;
}