threewire.h File Reference

Three-wire serial interface. More...

#include <ipxe/spi.h>
#include <limits.h>

Go to the source code of this file.

Macros
#define	THREEWIRE_READ   0x6
	Read data from memory array. More...
#define	THREEWIRE_WRITE   0x5
	Write data to memory array. More...
#define	THREEWIRE_EWEN   0x4
	Write enable. More...
#define	THREEWIRE_EWEN_ADDRESS   INT_MAX
	Address to be used for write enable command. More...
#define	THREEWIRE_WRITE_MDELAY   10
	Time to wait for write cycles to complete. More...

Functions
	FILE_LICENCE (GPL2_OR_LATER)
int	threewire_read (struct nvs_device *nvs, unsigned int address, void *data, size_t len)
	Read data from three-wire device. More...
int	threewire_write (struct nvs_device *nvs, unsigned int address, const void *data, size_t len)
	Write data to three-wire device. More...
int	threewire_detect_address_len (struct spi_device *device)
	Autodetect device address length. More...
static	__attribute__ ((always_inline)) void init_at93c06(struct spi_device *device
	Initialise Atmel AT93C06 serial EEPROM. More...
	init_at93cx6 (device, organisation)

Variables
static unsigned int	organisation
device nvs	block_size = 1
device	command_len = 3
device device nvs	read = threewire_read
device nvs	write = threewire_write
device	address_len = ( ( organisation == 8 ) ? 7 : 6 )

Detailed Description

Three-wire serial interface.

The Atmel three-wire interface is a subset of the (newer) SPI interface, and is implemented here as a layer on top of the SPI support.

Definition in file threewire.h.

Function Documentation

FILE_LICENCE()

FILE_LICENCE

(

GPL2_OR_LATER

)

threewire_read()

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

Read data from three-wire 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 47 of file threewire.c.

                                              {
        struct spi_device *device = nvs_to_spi ( nvs );
        struct spi_bus *bus = device->bus;
        int rc;

        assert ( bus->mode == SPI_MODE_THREEWIRE );

        DBGC ( device, "3wire %p reading %zd bytes at %04x\n",
               device, len, address );

        if ( ( rc = bus->rw ( bus, device, THREEWIRE_READ, address,
                              NULL, data, len ) ) != 0 ) {
                DBGC ( device, "3wire %p could not read: %s\n",
                       device, strerror ( rc ) );
                return rc;
        }

        return 0;
}

References address, assert(), bus, data, DBGC, len, NULL, spi_device::nvs, rc, SPI_MODE_THREEWIRE, strerror(), and THREEWIRE_READ.

Referenced by threewire_detect_address_len().

threewire_write()

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

Write data to three-wire 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 77 of file threewire.c.

                                                     {
        struct spi_device *device = nvs_to_spi ( nvs );
        struct spi_bus *bus = device->bus;
        int rc;

        assert ( bus->mode == SPI_MODE_THREEWIRE );

        DBGC ( device, "3wire %p writing %zd bytes at %04x\n",
               device, len, address );

        /* Enable device for writing */
        if ( ( rc = bus->rw ( bus, device, THREEWIRE_EWEN,
                              THREEWIRE_EWEN_ADDRESS, NULL, NULL, 0 ) ) != 0 ){
                DBGC ( device, "3wire %p could not enable writing: %s\n",
                       device, strerror ( rc ) );
                return rc;
        }

        /* Write data */
        if ( ( rc = bus->rw ( bus, device, THREEWIRE_WRITE, address,
                              data, NULL, len ) ) != 0 ) {
                DBGC ( device, "3wire %p could not write: %s\n",
                       device, strerror ( rc ) );
                return rc;
        }

        /* Our model of an SPI bus doesn't provide a mechanism for
         * "assert CS, wait for MISO to become high, so just wait for
         * long enough to ensure that the write has completed.
         */
        mdelay ( THREEWIRE_WRITE_MDELAY );

        return 0;
}

References address, assert(), bus, data, DBGC, len, mdelay(), NULL, spi_device::nvs, rc, SPI_MODE_THREEWIRE, strerror(), THREEWIRE_EWEN, THREEWIRE_EWEN_ADDRESS, THREEWIRE_WRITE, and THREEWIRE_WRITE_MDELAY.

threewire_detect_address_len()

int threewire_detect_address_len

(

struct spi_device *

device

)

Autodetect device address length.

Parameters

device

SPI device

Return values

rc	Return status code

Definition at line 119 of file threewire.c.

                                                               {
        struct nvs_device *nvs = &device->nvs;
        int rc;

        DBGC ( device, "3wire %p autodetecting address length\n", device );

        device->address_len = SPI_AUTODETECT_ADDRESS_LEN;
        if ( ( rc = threewire_read ( nvs, 0, NULL,
                                     ( 1 << nvs->word_len_log2 ) ) ) != 0 ) {
                DBGC ( device, "3wire %p could not autodetect address "
                       "length: %s\n", device, strerror ( rc ) );
                return rc;
        }

        DBGC ( device, "3wire %p autodetected address length %d\n",
               device, device->address_len );
        return 0;
}

References DBGC, NULL, rc, SPI_AUTODETECT_ADDRESS_LEN, strerror(), threewire_read(), and nvs_device::word_len_log2.

Referenced by ifec_init_eeprom().