1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
|
/*
* 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;
}
|
