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
|
/*
* Copyright 2007,2008 Free Software Foundation, Inc.
*
* 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 3 of the License, or
* (at your option) 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, see <http://www.gnu.org/licenses/>.
*/
#include "spi.h"
#include "memory_map.h"
#include "pic.h"
#include "nonstdio.h"
void (*volatile spi_callback)(void); //SPI callback when xfer complete.
void
spi_init(void)
{
/*
* f_sclk = f_wb / ((div + 1) * 2)
*/
spi_regs->div = 1; // 0 = Div by 2 (25 MHz); 1 = Div-by-4 (12.5 MHz)
}
void
spi_wait(void)
{
while (spi_regs->ctrl & SPI_CTRL_GO_BSY)
;
}
uint32_t
spi_transact(bool readback, int slave, uint32_t data, int length, uint32_t flags)
{
flags &= (SPI_CTRL_TXNEG | SPI_CTRL_RXNEG);
int ctrl = SPI_CTRL_ASS | (SPI_CTRL_CHAR_LEN_MASK & length) | flags;
spi_wait();
// Tell it which SPI slave device to access
spi_regs->ss = slave & 0xffff;
// Data we will send
spi_regs->txrx0 = data;
// Run it -- write once and rewrite with GO set
spi_regs->ctrl = ctrl;
spi_regs->ctrl = ctrl | SPI_CTRL_GO_BSY;
if(readback) {
spi_wait();
return spi_regs->txrx0;
}
else
return 0;
}
void spi_register_callback(void (*volatile callback)(void)) {
spi_callback = callback;
}
void spi_irq_handler(void) {
printf("SPI IRQ handler\n");
if(spi_callback) spi_callback(); //we could just use the PIC to register the user's callback, but this provides the ability to do other things later
}
uint32_t spi_get_data(void) {
return spi_regs->txrx0;
}
bool
spi_async_transact(int slave, uint32_t data, int length, uint32_t flags, void (*volatile callback)(void)) {
flags &= (SPI_CTRL_TXNEG | SPI_CTRL_RXNEG);
int ctrl = SPI_CTRL_ASS | (SPI_CTRL_CHAR_LEN_MASK & length) | flags;
if(spi_regs->ctrl & SPI_CTRL_GO_BSY) return false; //we don't wait on busy, we just return failure.
// Tell it which SPI slave device to access
spi_regs->ss = slave & 0xffff;
// Data we will send
spi_regs->txrx0 = data;
// Run it -- write once and rewrite with GO set
spi_regs->ctrl = ctrl;
spi_regs->ctrl = ctrl | SPI_CTRL_GO_BSY;
spi_regs->ctrl |= SPI_CTRL_IE; //we do these here so that we don't have to start the PIC before the SPI sets up the clocks on startup
pic_register_handler(IRQ_SPI, spi_irq_handler);
spi_register_callback(callback);
return true;
}
|
