| Detlev Zundel | 572e617 | 2009-03-30 00:31:32 +0200 | [diff] [blame] | 1 | /* |
| 2 | * (C) Copyright 2009 |
| 3 | * Detlev Zundel, DENX Software Engineering, dzu@denx.de. |
| 4 | * |
| Wolfgang Denk | 1a45966 | 2013-07-08 09:37:19 +0200 | [diff] [blame] | 5 | * SPDX-License-Identifier: GPL-2.0+ |
| Detlev Zundel | 572e617 | 2009-03-30 00:31:32 +0200 | [diff] [blame] | 6 | */ |
| 7 | |
| 8 | #define TWS_IMPLEMENTATION |
| 9 | #include <common.h> |
| 10 | |
| 11 | /*=====================================================================*/ |
| 12 | /* Public Functions */ |
| 13 | /*=====================================================================*/ |
| 14 | |
| 15 | /*----------------------------------------------------------------------- |
| 16 | * Read bits |
| 17 | */ |
| 18 | int tws_read(uchar *buffer, int len) |
| 19 | { |
| 20 | int rem = len; |
| 21 | uchar accu, shift; |
| 22 | |
| 23 | debug("tws_read: buffer %p len %d\n", buffer, len); |
| 24 | |
| 25 | /* Configure the data pin for input */ |
| 26 | tws_data_config_output(0); |
| 27 | |
| 28 | /* Disable WR, i.e. setup a read */ |
| 29 | tws_wr(0); |
| 30 | udelay(1); |
| 31 | |
| 32 | /* Rise CE */ |
| 33 | tws_ce(1); |
| 34 | udelay(1); |
| 35 | |
| 36 | for (; rem > 0; ) { |
| 37 | for (shift = 0, accu = 0; |
| 38 | (rem > 0) && (shift < 8); |
| 39 | rem--, shift++) { |
| 40 | tws_clk(1); |
| 41 | udelay(10); |
| 42 | accu |= (tws_data_read() << shift); /* LSB first */ |
| 43 | tws_clk(0); |
| 44 | udelay(10); |
| 45 | } |
| 46 | *buffer++ = accu; |
| 47 | } |
| 48 | |
| 49 | /* Lower CE */ |
| 50 | tws_ce(0); |
| 51 | |
| 52 | return len - rem; |
| 53 | } |
| 54 | |
| 55 | |
| 56 | /*----------------------------------------------------------------------- |
| 57 | * Write bits |
| 58 | */ |
| 59 | int tws_write(uchar *buffer, int len) |
| 60 | { |
| 61 | int rem = len; |
| 62 | uchar accu, shift; |
| 63 | |
| 64 | debug("tws_write: buffer %p len %d\n", buffer, len); |
| 65 | |
| 66 | /* Configure the data pin for output */ |
| 67 | tws_data_config_output(1); |
| 68 | |
| 69 | /* Enable WR, i.e. setup a write */ |
| 70 | tws_wr(1); |
| 71 | udelay(1); |
| 72 | |
| 73 | /* Rise CE */ |
| 74 | tws_ce(1); |
| 75 | udelay(1); |
| 76 | |
| 77 | for (; rem > 0; ) { |
| 78 | for (shift = 0, accu = *buffer++; |
| 79 | (rem > 0) && (shift < 8); |
| 80 | rem--, shift++) { |
| 81 | tws_data(accu & 0x01); /* LSB first */ |
| 82 | tws_clk(1); |
| 83 | udelay(10); |
| 84 | tws_clk(0); |
| 85 | udelay(10); |
| 86 | accu >>= 1; |
| 87 | } |
| 88 | } |
| 89 | |
| 90 | /* Lower CE */ |
| 91 | tws_ce(0); |
| 92 | |
| 93 | return len - rem; |
| 94 | } |