1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
|
/*
* linux/arch/arm/kernel/iic.c
*
* Copyright (C) 1995, 1996 Russell King
*
* IIC is used to get the current time from the CMOS rtc.
*/
#include <linux/delay.h>
#include <linux/errno.h>
#include <asm/system.h>
#include <asm/hardware.h>
#include <asm/io.h>
#include <asm/ioc.h>
#define FORCE_ONES 0xdc
/*
* if delay loop has been calibrated then us that,
* else use IOC timer 1.
*/
static void iic_delay(void)
{
extern unsigned long loops_per_sec;
if (loops_per_sec != (1 << 12)) {
udelay(100); /* was 10 */
return;
} else {
unsigned long flags;
save_flags_cli(flags);
outb(254, IOC_T1LTCHL);
outb(255, IOC_T1LTCHH);
outb(0, IOC_T1GO);
outb(1<<6, IOC_IRQCLRA); /* clear T1 irq */
outb(10, IOC_T1LTCHL); /* was 4 */
outb(0, IOC_T1LTCHH);
outb(0, IOC_T1GO);
while ((inb(IOC_IRQSTATA) & (1<<6)) == 0);
restore_flags(flags);
}
}
#define IIC_INIT() dat = (inb(IOC_CONTROL) | FORCE_ONES) & ~3
#define IIC_SET_DAT outb(dat|=1, IOC_CONTROL);
#define IIC_CLR_DAT outb(dat&=~1, IOC_CONTROL);
#define IIC_SET_CLK outb(dat|=2, IOC_CONTROL);
#define IIC_CLR_CLK outb(dat&=~2, IOC_CONTROL);
#define IIC_DELAY iic_delay();
#define IIC_READ_DATA() (inb(IOC_CONTROL) & 1)
static inline void iic_set_lines(int clk, int dat)
{
int old;
old = inb(IOC_CONTROL) | FORCE_ONES;
old &= ~3;
if (clk)
old |= 2;
if (dat)
old |= 1;
outb(old, IOC_CONTROL);
iic_delay();
}
static inline unsigned int iic_read_data(void)
{
return inb(IOC_CONTROL) & 1;
}
/*
* C: ==~~_
* D: =~~__
*/
static inline void iic_start(void)
{
unsigned int dat;
IIC_INIT();
IIC_SET_DAT
IIC_DELAY
IIC_SET_CLK
IIC_DELAY
IIC_CLR_DAT
IIC_DELAY
IIC_CLR_CLK
IIC_DELAY
}
/*
* C: __~~
* D: =__~
*/
static inline void iic_stop(void)
{
unsigned int dat;
IIC_INIT();
IIC_CLR_DAT
IIC_DELAY
IIC_SET_CLK
IIC_DELAY
IIC_SET_DAT
IIC_DELAY
}
/*
* C: __~_
* D: =___
*/
static inline void iic_acknowledge(void)
{
unsigned int dat;
IIC_INIT();
IIC_CLR_DAT
IIC_DELAY
IIC_SET_CLK
IIC_DELAY
IIC_CLR_CLK
IIC_DELAY
}
/*
* C: __~_
* D: =~H~
*/
static inline int iic_is_acknowledged(void)
{
unsigned int dat, ack_bit;
IIC_INIT();
IIC_SET_DAT
IIC_DELAY
IIC_SET_CLK
IIC_DELAY
ack_bit = IIC_READ_DATA();
IIC_CLR_CLK
IIC_DELAY
return ack_bit == 0;
}
/*
* C: _~__~__~__~__~__~__~__~_
* D: =DDXDDXDDXDDXDDXDDXDDXDD
*/
static void iic_sendbyte(unsigned int b)
{
unsigned int dat, i;
IIC_INIT();
for (i = 0; i < 8; i++) {
if (b & 128)
IIC_SET_DAT
else
IIC_CLR_DAT
IIC_DELAY
IIC_SET_CLK
IIC_DELAY
IIC_CLR_CLK
IIC_DELAY
b <<= 1;
}
}
/*
* C: __~_~_~_~_~_~_~_~_
* D: =~HHHHHHHHHHHHHHHH
*/
static unsigned char iic_recvbyte(void)
{
unsigned int dat, i, in;
IIC_INIT();
IIC_SET_DAT
IIC_DELAY
in = 0;
for (i = 0; i < 8; i++) {
IIC_SET_CLK
IIC_DELAY
in = (in << 1) | IIC_READ_DATA();
IIC_CLR_CLK
IIC_DELAY
}
return in;
}
int iic_control (unsigned char addr, unsigned char loc, unsigned char *buf, int len)
{
int i, err = -EIO;
iic_start();
iic_sendbyte(addr & 0xfe);
if (!iic_is_acknowledged())
goto error;
iic_sendbyte(loc);
if (!iic_is_acknowledged())
goto error;
if (addr & 1) {
iic_stop();
iic_start();
iic_sendbyte(addr|1);
if (!iic_is_acknowledged())
goto error;
for (i = 0; i < len - 1; i++) {
buf[i] = iic_recvbyte();
iic_acknowledge();
}
buf[i] = iic_recvbyte();
} else {
for (i = 0; i < len; i++) {
iic_sendbyte(buf[i]);
if (!iic_is_acknowledged())
goto error;
}
}
err = 0;
error:
iic_stop();
return err;
}
|
