Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
Added generic SPI protocol handler with read and write support.
- Loading branch information
Michael Brown
committed
Dec 4, 2006
1 parent
946967f
commit 1961ba4
Showing
2 changed files
with
127 additions
and
0 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,122 @@ | ||
/* | ||
* 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. | ||
*/ | ||
|
||
#include <stddef.h> | ||
#include <errno.h> | ||
#include <timer.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, unsigned int 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 ); | ||
|
||
return bus->rw ( bus, device, command, address, NULL, data, len ); | ||
} | ||
|
||
/** | ||
* 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, unsigned int 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; | ||
|
||
if ( ( rc = bus->rw ( bus, device, SPI_WREN, -1, | ||
NULL, NULL, 0 ) ) != 0 ) | ||
return rc; | ||
|
||
if ( ( rc = bus->rw ( bus, device, command, address, | ||
data, NULL, len ) ) != 0 ) | ||
return rc; | ||
|
||
if ( ( rc = spi_wait ( device ) ) != 0 ) | ||
return rc; | ||
|
||
return 0; | ||
} | ||
|
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters