threewire.h File Reference

Three-wire serial interface. More...

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

Go to the source code of this file.

Defines
#define	THREEWIRE_READ   0x6
	Read data from memory array.
#define	THREEWIRE_WRITE   0x5
	Write data to memory array.
#define	THREEWIRE_EWEN   0x4
	Write enable.
#define	THREEWIRE_EWEN_ADDRESS   INT_MAX
	Address to be used for write enable command.
#define	THREEWIRE_WRITE_MDELAY   10
	Time to wait for write cycles to complete.
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.
int	threewire_write (struct nvs_device *nvs, unsigned int address, const void *data, size_t len)
	Write data to three-wire device.
int	threewire_detect_address_len (struct spi_device *device)
	Autodetect device address length.
static	__attribute__ ((always_inline)) void init_at93cx6(struct spi_device *device

---

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

(

GPL2_OR_LATER

)

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.

References assert, spi_device::bus, bus, DBGC, spi_bus::mode, NULL, rc, spi_bus::rw, SPI_MODE_THREEWIRE, strerror(), and THREEWIRE_READ.

Referenced by threewire_detect_address_len().

                                              {
        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;
}

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.

References assert, spi_device::bus, bus, DBGC, mdelay(), spi_bus::mode, NULL, rc, spi_bus::rw, SPI_MODE_THREEWIRE, strerror(), THREEWIRE_EWEN, THREEWIRE_EWEN_ADDRESS, THREEWIRE_WRITE, and THREEWIRE_WRITE_MDELAY.

                                                     {
        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;
}

int threewire_detect_address_len

(

struct spi_device *

device

)

Autodetect device address length.

device SPI device rc Return status code

Definition at line 119 of file threewire.c.

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

Referenced by ifec_init_eeprom().

                                                               {
        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;
}