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
|
/*
ChibiOS/RT - Copyright (C) 2006-2007 Giovanni Di Sirio.
This file is part of ChibiOS/RT.
ChibiOS/RT 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.
ChibiOS/RT 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/>.
*/
/**
* @file LPC214x/lpc214x_ssp.c
* @brief LPC214x SSP driver code.
* @addtogroup LPC214x_SSP
* @{
*/
#include <ch.h>
#include <pal.h>
#include "lpc214x.h"
#include "lpc214x_ssp.h"
#if LPC214x_SSP_USE_MUTEX
static Semaphore me;
#endif
/**
* @brief Aquires access to the SSP bus.
* @note This function also handles the mutual exclusion on the SSP bus if
* the @p LPC214x_SSP_USE_MUTEX option is enabled.
*/
void sspAcquireBus(void) {
#if LPC214x_SSP_USE_MUTEX
chSemWait(&me);
#endif
palClearPad(IOPORT1, 20);
}
/**
* @brief Releases the SSP bus.
* @note This function also handles the mutual exclusion on the SSP bus if
* the @p LPC214x_SSP_USE_MUTEX option is enabled.
*/
void sspReleaseBus(void) {
palClearPad(IOPORT1, 20);
#if LPC214x_SSP_USE_MUTEX
chSemSignal(&me);
#endif
}
/**
* @brief Synchronous SSP transfer.
* @param[in] in pointer to the incoming data buffer, if this parameter is set
* to @p NULL then the incoming data is discarded
* @param[out] out pointer to the outgoing data buffer, if this parameter is
* set to @p NULL then 0xFF bytes will be output
* @param[in] n the number of bytes to be transferred
* @note The transfer is performed in a software loop and is not interrupt
* driven for performance reasons, this function should be invoked
* by a low priority thread in order to "play nice" with the
* rest of the system. This kind of peripheral would really need a
* dedicated DMA channel.
*/
void sspRW(uint8_t *in, uint8_t *out, size_t n) {
int icnt, ocnt;
SSP *ssp = SSPBase;
icnt = ocnt = n;
while (icnt) {
if (ssp->SSP_SR & SR_RNE) {
if (in)
*in++ = ssp->SSP_DR;
else
ssp->SSP_DR;
icnt--;
continue; /* Priority over transmission. */
}
if (ocnt && (ssp->SSP_SR & SR_TNF)) {
if (out)
ssp->SSP_DR = *out++;
else
ssp->SSP_DR = 0xFF;
ocnt--;
}
}
}
/**
* @brief SSP setup.
* @param[in] cpsr the value for the @p CPSR register
* @param[in] cr0 the value for the @p CR0 register
* @param[in] cr1 the value for the @p CR1 register
*/
void ssp_setup(int cpsr, int cr0, int cr1) {
SSP *ssp = SSPBase;
ssp->SSP_CR1 = 0;
ssp->SSP_CR0 = cr0;
ssp->SSP_CPSR = cpsr;
ssp->SSP_CR1 = cr1 | CR1_SSE;
}
/**
* @brief SSP subsystem initialization.
*/
void ssp_init(void) {
/* Enables the SPI1 clock */
PCONP = (PCONP & PCALL) | PCSPI1;
/* Clock = PCLK / 2 (fastest). */
ssp_setup(2, CR0_DSS8BIT | CR0_FRFSPI | CR0_CLOCKRATE(0), 0);
#if LPC214x_SSP_USE_MUTEX
chSemInit(&me, 1);
#endif
}
/** @} */
|
