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 */
tws_read(uchar * buffer,int len)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 */
tws_write(uchar * buffer,int len)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 }
112