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
|
#ifndef _GPXE_SPI_H
#define _GPXE_SPI_H
/** @file
*
* SPI interface
*
*/
#include <gpxe/bitbash.h>
/** An SPI interface */
struct spi_interface {
/** SPI interface mode
*
* This is the bitwise OR of zero or more of @c SPI_MODE_CPHA
* and @c SPI_MODE_CPOL. It is also the number conventionally
* used to describe the SPI interface mode. For example, SPI
* mode 1 is the mode in which CPOL=0 and CPHA=1, which
* therefore corresponds to a mode value of (0|SPI_MODE_CPHA)
* which, happily, equals 1.
*/
unsigned int mode;
/**
* Select slave
*
* @v spi SPI interface
* @v slave Slave number
*/
void ( * select_slave ) ( struct spi_interface *spi,
unsigned int slave );
/**
* Deselect slave
*
* @v spi SPI interface
*/
void ( * deselect_slave ) ( struct spi_interface *spi );
/**
* Transfer bits over SPI bit-bashing interface
*
* @v spi SPI interface
* @v data_out TX data buffer (or NULL)
* @v data_in RX data buffer (or NULL)
* @v len Length of transfer (in @b bits)
*/
void ( * transfer ) ( struct spi_interface *spi, const void *data_out,
void *data_in, unsigned int len );
};
/** Clock phase (CPHA) mode bit
*
* Phase 0 is sample on rising edge, shift data on falling edge.
*
* Phase 1 is shift data on rising edge, sample data on falling edge.
*/
#define SPI_MODE_CPHA 0x01
/** Clock polarity (CPOL) mode bit
*
* This bit reflects the idle state of the clock line (SCLK).
*/
#define SPI_MODE_CPOL 0x02
/** Slave select polarity mode bit
*
* This bit reflects that active state of the slave select lines. It
* is not part of the normal SPI mode number (which covers only @c
* SPI_MODE_CPOL and @c SPI_MODE_CPHA), but is included here for
* convenience.
*/
#define SPI_MODE_SSPOL 0x10
/** Microwire-compatible mode
*
* This is SPI mode 1 (i.e. CPOL=0, CPHA=1), and is compatible with
* the original Microwire protocol.
*/
#define SPI_MODE_MICROWIRE 1
/** Microwire/Plus-compatible mode
*
* This is SPI mode 0 (i.e. CPOL=0, CPHA=0), and is compatible with
* the Microwire/Plus protocol
*/
#define SPI_MODE_MICROWIRE_PLUS 0
/** Threewire-compatible mode
*
* This mode is compatible with Atmel's series of "three-wire"
* interfaces.
*/
#define SPI_MODE_THREEWIRE ( SPI_MODE_MICROWIRE_PLUS | SPI_MODE_SSPOL )
/** A bit-bashing SPI interface */
struct spi_bit_basher {
/** SPI interface */
struct spi_interface spi;
/** Bit-bashing interface */
struct bit_basher basher;
/** Currently selected slave
*
* Valid only when a slave is actually selected.
*/
unsigned int slave;
};
/** Bit indices used for SPI bit-bashing interface */
enum {
/** Serial clock */
SPI_BIT_SCLK = 0,
/** Master Out Slave In */
SPI_BIT_MOSI,
/** Master In Slave Out */
SPI_BIT_MISO,
/** Slave 0 select */
SPI_BIT_SS0,
};
/**
* Determine bit index for a particular slave
*
* @v slave Slave number
* @ret index Bit index (i.e. SPI_BIT_SSN, where N=slave)
*/
#define SPI_BIT_SS( slave ) ( SPI_BIT_SS0 + (slave) )
/** Delay between SCLK transitions */
#define SPI_UDELAY 1
extern void init_spi_bit_basher ( struct spi_bit_basher *spibit );
#endif /* _GPXE_SPI_H */
|
