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wdenke3093092002-10-01 01:07:28 +00001/*
2 * (C) Copyright 2002
3 * Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com.
4 *
5 * Influenced by code from:
6 * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
7 *
8 * See file CREDITS for list of people who contributed to this
9 * project.
10 *
11 * This program is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU General Public License as
13 * published by the Free Software Foundation; either version 2 of
14 * the License, or (at your option) any later version.
15 *
16 * This program is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 * GNU General Public License for more details.
20 *
21 * You should have received a copy of the GNU General Public License
22 * along with this program; if not, write to the Free Software
23 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
24 * MA 02111-1307 USA
25 */
26
27#include <common.h>
28#include <spi.h>
29
30#if defined(CONFIG_SOFT_SPI)
31
wdenke3093092002-10-01 01:07:28 +000032/*-----------------------------------------------------------------------
33 * Definitions
34 */
35
36#ifdef DEBUG_SPI
37#define PRINTD(fmt,args...) printf (fmt ,##args)
38#else
39#define PRINTD(fmt,args...)
40#endif
41
42
wdenke3093092002-10-01 01:07:28 +000043/*=====================================================================*/
44/* Public Functions */
45/*=====================================================================*/
46
47/*-----------------------------------------------------------------------
48 * Initialization
49 */
50void spi_init (void)
51{
52#ifdef SPI_INIT
53 volatile immap_t *immr = (immap_t *)CFG_IMMR;
54
55 SPI_INIT;
56#endif
57}
58
59
60/*-----------------------------------------------------------------------
61 * SPI transfer
62 *
63 * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks
64 * "bitlen" bits in the SPI MISO port. That's just the way SPI works.
65 *
66 * The source of the outgoing bits is the "dout" parameter and the
67 * destination of the input bits is the "din" parameter. Note that "dout"
68 * and "din" can point to the same memory location, in which case the
69 * input data overwrites the output data (since both are buffered by
70 * temporary variables, this is OK).
71 *
72 * If the chipsel() function is not NULL, it is called with a parameter
73 * of '1' (chip select active) at the start of the transfer and again with
74 * a parameter of '0' at the end of the transfer.
75 *
76 * If the chipsel() function _is_ NULL, it the responsibility of the
77 * caller to make the appropriate chip select active before calling
78 * spi_xfer() and making it inactive after spi_xfer() returns.
79 */
80int spi_xfer(spi_chipsel_type chipsel, int bitlen, uchar *dout, uchar *din)
81{
82 volatile immap_t *immr = (immap_t *)CFG_IMMR;
83 uchar tmpdin = 0;
84 uchar tmpdout = 0;
85 int j;
86
87 PRINTD("spi_xfer: chipsel %08X dout %08X din %08X bitlen %d\n",
88 (int)chipsel, *(uint *)dout, *(uint *)din, bitlen);
89
90 if(chipsel != NULL) {
91 (*chipsel)(1); /* select the target chip */
92 }
93
94 for(j = 0; j < bitlen; j++) {
95 /*
96 * Check if it is time to work on a new byte.
97 */
98 if((j % 8) == 0) {
99 tmpdout = *dout++;
100 if(j != 0) {
101 *din++ = tmpdin;
102 }
103 tmpdin = 0;
104 }
105 SPI_SCL(0);
106 SPI_SDA(tmpdout & 0x80);
107 SPI_DELAY;
108 SPI_SCL(1);
109 SPI_DELAY;
110 tmpdin <<= 1;
111 tmpdin |= SPI_READ;
112 tmpdout <<= 1;
113 }
114 /*
115 * If the number of bits isn't a multiple of 8, shift the last
116 * bits over to left-justify them. Then store the last byte
117 * read in.
118 */
119 if((bitlen % 8) != 0)
120 tmpdin <<= 8 - (bitlen % 8);
121 *din++ = tmpdin;
122
123 SPI_SCL(0); /* SPI wants the clock left low for idle */
124
125 if(chipsel != NULL) {
126 (*chipsel)(0); /* deselect the target chip */
127
128 }
129
130 return(0);
131}
132
133#endif /* CONFIG_SOFT_SPI */