/*
* 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 <errno.h>
#include <unistd.h>
#include <gpxe/spi.h>
/** @file
*
* SPI devices
*
*/
/**
* Munge SPI device address into command
*
* @v command SPI command
* @v address Address
* @v munge_address Device requires address munging
* @ret 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.
*/
static inline unsigned int spi_command ( unsigned int command,
unsigned int address,
int munge_address ) {
return ( command | ( ( ( address >> 8 ) & munge_address ) << 3 ) );
}
/**
* Wait for SPI device to complete operation
*
* @v device SPI device
* @ret rc Return status code
*/
static int spi_wait ( struct spi_device *device ) {
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;
}
/**
* Read data from SPI 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 spi_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;
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;
}
/**
* Write data to SPI 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 spi_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;
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;
}
