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e3093091 WD |
1 | /* |
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 | ||
e3093091 WD |
32 | /*----------------------------------------------------------------------- |
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 | ||
43 | ||
44 | /*=====================================================================*/ | |
45 | /* Public Functions */ | |
46 | /*=====================================================================*/ | |
47 | ||
48 | /*----------------------------------------------------------------------- | |
49 | * Initialization | |
50 | */ | |
51 | void spi_init (void) | |
52 | { | |
53 | #ifdef SPI_INIT | |
54 | volatile immap_t *immr = (immap_t *)CFG_IMMR; | |
55 | ||
56 | SPI_INIT; | |
57 | #endif | |
58 | } | |
59 | ||
60 | ||
61 | /*----------------------------------------------------------------------- | |
62 | * SPI transfer | |
63 | * | |
64 | * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks | |
65 | * "bitlen" bits in the SPI MISO port. That's just the way SPI works. | |
66 | * | |
67 | * The source of the outgoing bits is the "dout" parameter and the | |
68 | * destination of the input bits is the "din" parameter. Note that "dout" | |
69 | * and "din" can point to the same memory location, in which case the | |
70 | * input data overwrites the output data (since both are buffered by | |
71 | * temporary variables, this is OK). | |
72 | * | |
73 | * If the chipsel() function is not NULL, it is called with a parameter | |
74 | * of '1' (chip select active) at the start of the transfer and again with | |
75 | * a parameter of '0' at the end of the transfer. | |
76 | * | |
77 | * If the chipsel() function _is_ NULL, it the responsibility of the | |
78 | * caller to make the appropriate chip select active before calling | |
79 | * spi_xfer() and making it inactive after spi_xfer() returns. | |
80 | */ | |
81 | int spi_xfer(spi_chipsel_type chipsel, int bitlen, uchar *dout, uchar *din) | |
82 | { | |
83 | volatile immap_t *immr = (immap_t *)CFG_IMMR; | |
84 | uchar tmpdin = 0; | |
85 | uchar tmpdout = 0; | |
86 | int j; | |
87 | ||
88 | PRINTD("spi_xfer: chipsel %08X dout %08X din %08X bitlen %d\n", | |
89 | (int)chipsel, *(uint *)dout, *(uint *)din, bitlen); | |
90 | ||
91 | if(chipsel != NULL) { | |
92 | (*chipsel)(1); /* select the target chip */ | |
93 | } | |
94 | ||
95 | for(j = 0; j < bitlen; j++) { | |
96 | /* | |
97 | * Check if it is time to work on a new byte. | |
98 | */ | |
99 | if((j % 8) == 0) { | |
100 | tmpdout = *dout++; | |
101 | if(j != 0) { | |
102 | *din++ = tmpdin; | |
103 | } | |
104 | tmpdin = 0; | |
105 | } | |
106 | SPI_SCL(0); | |
107 | SPI_SDA(tmpdout & 0x80); | |
108 | SPI_DELAY; | |
109 | SPI_SCL(1); | |
110 | SPI_DELAY; | |
111 | tmpdin <<= 1; | |
112 | tmpdin |= SPI_READ; | |
113 | tmpdout <<= 1; | |
114 | } | |
115 | /* | |
116 | * If the number of bits isn't a multiple of 8, shift the last | |
117 | * bits over to left-justify them. Then store the last byte | |
118 | * read in. | |
119 | */ | |
120 | if((bitlen % 8) != 0) | |
121 | tmpdin <<= 8 - (bitlen % 8); | |
122 | *din++ = tmpdin; | |
123 | ||
124 | SPI_SCL(0); /* SPI wants the clock left low for idle */ | |
125 | ||
126 | if(chipsel != NULL) { | |
127 | (*chipsel)(0); /* deselect the target chip */ | |
128 | ||
129 | } | |
130 | ||
131 | return(0); | |
132 | } | |
133 | ||
134 | #endif /* CONFIG_SOFT_SPI */ | |
135 |