| Detlev Zundel | a9036ab | 2009-03-30 00:31:32 +0200 | [diff] [blame] | 1 | /* |
| 2 | * (C) Copyright 2009 |
| 3 | * Detlev Zundel, DENX Software Engineering, dzu@denx.de. |
| 4 | * |
| 5 | * See file CREDITS for list of people who contributed to this |
| 6 | * project. |
| 7 | * |
| 8 | * This program is free software; you can redistribute it and/or |
| 9 | * modify it under the terms of the GNU General Public License as |
| 10 | * published by the Free Software Foundation; either version 2 of |
| 11 | * the License, or (at your option) any later version. |
| 12 | * |
| 13 | * This program is distributed in the hope that it will be useful, |
| 14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 16 | * GNU General Public License for more details. |
| 17 | * |
| 18 | * You should have received a copy of the GNU General Public License |
| 19 | * along with this program; if not, write to the Free Software |
| 20 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, |
| 21 | * MA 02111-1307 USA |
| 22 | * |
| 23 | */ |
| 24 | |
| 25 | #define TWS_IMPLEMENTATION |
| 26 | #include <common.h> |
| 27 | |
| 28 | /*=====================================================================*/ |
| 29 | /* Public Functions */ |
| 30 | /*=====================================================================*/ |
| 31 | |
| 32 | /*----------------------------------------------------------------------- |
| 33 | * Read bits |
| 34 | */ |
| 35 | int tws_read(uchar *buffer, int len) |
| 36 | { |
| 37 | int rem = len; |
| 38 | uchar accu, shift; |
| 39 | |
| 40 | debug("tws_read: buffer %p len %d\n", buffer, len); |
| 41 | |
| 42 | /* Configure the data pin for input */ |
| 43 | tws_data_config_output(0); |
| 44 | |
| 45 | /* Disable WR, i.e. setup a read */ |
| 46 | tws_wr(0); |
| 47 | udelay(1); |
| 48 | |
| 49 | /* Rise CE */ |
| 50 | tws_ce(1); |
| 51 | udelay(1); |
| 52 | |
| 53 | for (; rem > 0; ) { |
| 54 | for (shift = 0, accu = 0; |
| 55 | (rem > 0) && (shift < 8); |
| 56 | rem--, shift++) { |
| 57 | tws_clk(1); |
| 58 | udelay(10); |
| 59 | accu |= (tws_data_read() << shift); /* LSB first */ |
| 60 | tws_clk(0); |
| 61 | udelay(10); |
| 62 | } |
| 63 | *buffer++ = accu; |
| 64 | } |
| 65 | |
| 66 | /* Lower CE */ |
| 67 | tws_ce(0); |
| 68 | |
| 69 | return len - rem; |
| 70 | } |
| 71 | |
| 72 | |
| 73 | /*----------------------------------------------------------------------- |
| 74 | * Write bits |
| 75 | */ |
| 76 | int tws_write(uchar *buffer, int len) |
| 77 | { |
| 78 | int rem = len; |
| 79 | uchar accu, shift; |
| 80 | |
| 81 | debug("tws_write: buffer %p len %d\n", buffer, len); |
| 82 | |
| 83 | /* Configure the data pin for output */ |
| 84 | tws_data_config_output(1); |
| 85 | |
| 86 | /* Enable WR, i.e. setup a write */ |
| 87 | tws_wr(1); |
| 88 | udelay(1); |
| 89 | |
| 90 | /* Rise CE */ |
| 91 | tws_ce(1); |
| 92 | udelay(1); |
| 93 | |
| 94 | for (; rem > 0; ) { |
| 95 | for (shift = 0, accu = *buffer++; |
| 96 | (rem > 0) && (shift < 8); |
| 97 | rem--, shift++) { |
| 98 | tws_data(accu & 0x01); /* LSB first */ |
| 99 | tws_clk(1); |
| 100 | udelay(10); |
| 101 | tws_clk(0); |
| 102 | udelay(10); |
| 103 | accu >>= 1; |
| 104 | } |
| 105 | } |
| 106 | |
| 107 | /* Lower CE */ |
| 108 | tws_ce(0); |
| 109 | |
| 110 | return len - rem; |
| 111 | } |