wdenk | e309309 | 2002-10-01 01:07:28 +0000 | [diff] [blame^] | 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 | |
| 32 | #define DEBUG_SPI |
| 33 | |
| 34 | |
| 35 | /*----------------------------------------------------------------------- |
| 36 | * Definitions |
| 37 | */ |
| 38 | |
| 39 | #ifdef DEBUG_SPI |
| 40 | #define PRINTD(fmt,args...) printf (fmt ,##args) |
| 41 | #else |
| 42 | #define PRINTD(fmt,args...) |
| 43 | #endif |
| 44 | |
| 45 | |
| 46 | |
| 47 | /*=====================================================================*/ |
| 48 | /* Public Functions */ |
| 49 | /*=====================================================================*/ |
| 50 | |
| 51 | /*----------------------------------------------------------------------- |
| 52 | * Initialization |
| 53 | */ |
| 54 | void spi_init (void) |
| 55 | { |
| 56 | #ifdef SPI_INIT |
| 57 | volatile immap_t *immr = (immap_t *)CFG_IMMR; |
| 58 | |
| 59 | SPI_INIT; |
| 60 | #endif |
| 61 | } |
| 62 | |
| 63 | |
| 64 | /*----------------------------------------------------------------------- |
| 65 | * SPI transfer |
| 66 | * |
| 67 | * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks |
| 68 | * "bitlen" bits in the SPI MISO port. That's just the way SPI works. |
| 69 | * |
| 70 | * The source of the outgoing bits is the "dout" parameter and the |
| 71 | * destination of the input bits is the "din" parameter. Note that "dout" |
| 72 | * and "din" can point to the same memory location, in which case the |
| 73 | * input data overwrites the output data (since both are buffered by |
| 74 | * temporary variables, this is OK). |
| 75 | * |
| 76 | * If the chipsel() function is not NULL, it is called with a parameter |
| 77 | * of '1' (chip select active) at the start of the transfer and again with |
| 78 | * a parameter of '0' at the end of the transfer. |
| 79 | * |
| 80 | * If the chipsel() function _is_ NULL, it the responsibility of the |
| 81 | * caller to make the appropriate chip select active before calling |
| 82 | * spi_xfer() and making it inactive after spi_xfer() returns. |
| 83 | */ |
| 84 | int spi_xfer(spi_chipsel_type chipsel, int bitlen, uchar *dout, uchar *din) |
| 85 | { |
| 86 | volatile immap_t *immr = (immap_t *)CFG_IMMR; |
| 87 | uchar tmpdin = 0; |
| 88 | uchar tmpdout = 0; |
| 89 | int j; |
| 90 | |
| 91 | PRINTD("spi_xfer: chipsel %08X dout %08X din %08X bitlen %d\n", |
| 92 | (int)chipsel, *(uint *)dout, *(uint *)din, bitlen); |
| 93 | |
| 94 | if(chipsel != NULL) { |
| 95 | (*chipsel)(1); /* select the target chip */ |
| 96 | } |
| 97 | |
| 98 | for(j = 0; j < bitlen; j++) { |
| 99 | /* |
| 100 | * Check if it is time to work on a new byte. |
| 101 | */ |
| 102 | if((j % 8) == 0) { |
| 103 | tmpdout = *dout++; |
| 104 | if(j != 0) { |
| 105 | *din++ = tmpdin; |
| 106 | } |
| 107 | tmpdin = 0; |
| 108 | } |
| 109 | SPI_SCL(0); |
| 110 | SPI_SDA(tmpdout & 0x80); |
| 111 | SPI_DELAY; |
| 112 | SPI_SCL(1); |
| 113 | SPI_DELAY; |
| 114 | tmpdin <<= 1; |
| 115 | tmpdin |= SPI_READ; |
| 116 | tmpdout <<= 1; |
| 117 | } |
| 118 | /* |
| 119 | * If the number of bits isn't a multiple of 8, shift the last |
| 120 | * bits over to left-justify them. Then store the last byte |
| 121 | * read in. |
| 122 | */ |
| 123 | if((bitlen % 8) != 0) |
| 124 | tmpdin <<= 8 - (bitlen % 8); |
| 125 | *din++ = tmpdin; |
| 126 | |
| 127 | SPI_SCL(0); /* SPI wants the clock left low for idle */ |
| 128 | |
| 129 | if(chipsel != NULL) { |
| 130 | (*chipsel)(0); /* deselect the target chip */ |
| 131 | |
| 132 | } |
| 133 | |
| 134 | return(0); |
| 135 | } |
| 136 | |
| 137 | #endif /* CONFIG_SOFT_SPI */ |
| 138 | |