/*
* Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
FILE_LICENCE ( GPL2_OR_LATER );
#include <stddef.h>
#include <string.h>
#include <assert.h>
#include <unistd.h>
#include <gpxe/threewire.h>
/** @file
*
* Three-wire serial devices
*
*/
/**
* Read data from three-wire device
*
* @v nvs NVS device
* @v address Address from which to read
* @v data Data buffer
* @v len Length of data buffer
* @ret rc Return status code
*/
int threewire_read ( struct nvs_device *nvs, unsigned int address,
void *data, size_t 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;
}
/**
* Write data to three-wire device
*
* @v nvs NVS device
* @v address Address from which to read
* @v data Data buffer
* @v len Length of data buffer
* @ret rc Return status code
*/
int threewire_write ( struct nvs_device *nvs, unsigned int address,
const void *data, size_t 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 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;
}
/**
* Autodetect device address length
*
* @v device SPI device
* @ret rc Return status code
*/
int threewire_detect_address_len ( struct spi_device *device ) {
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;
}
