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
|
/*
* i2c-algo-sgi.c: i2c driver algorithms for SGI adapters.
*
* This file is subject to the terms and conditions of the GNU General Public
* License version 2 as published by the Free Software Foundation.
*
* Copyright (C) 2003 Ladislav Michl <ladis@linux-mips.org>
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/i2c-algo-sgi.h>
#define SGI_I2C_FORCE_IDLE (0 << 0)
#define SGI_I2C_NOT_IDLE (1 << 0)
#define SGI_I2C_WRITE (0 << 1)
#define SGI_I2C_READ (1 << 1)
#define SGI_I2C_RELEASE_BUS (0 << 2)
#define SGI_I2C_HOLD_BUS (1 << 2)
#define SGI_I2C_XFER_DONE (0 << 4)
#define SGI_I2C_XFER_BUSY (1 << 4)
#define SGI_I2C_ACK (0 << 5)
#define SGI_I2C_NACK (1 << 5)
#define SGI_I2C_BUS_OK (0 << 7)
#define SGI_I2C_BUS_ERR (1 << 7)
#define get_control() adap->getctrl(adap->data)
#define set_control(val) adap->setctrl(adap->data, val)
#define read_data() adap->rdata(adap->data)
#define write_data(val) adap->wdata(adap->data, val)
static int wait_xfer_done(struct i2c_algo_sgi_data *adap)
{
int i;
for (i = 0; i < adap->xfer_timeout; i++) {
if ((get_control() & SGI_I2C_XFER_BUSY) == 0)
return 0;
udelay(1);
}
return -ETIMEDOUT;
}
static int wait_ack(struct i2c_algo_sgi_data *adap)
{
int i;
if (wait_xfer_done(adap))
return -ETIMEDOUT;
for (i = 0; i < adap->ack_timeout; i++) {
if ((get_control() & SGI_I2C_NACK) == 0)
return 0;
udelay(1);
}
return -ETIMEDOUT;
}
static int force_idle(struct i2c_algo_sgi_data *adap)
{
int i;
set_control(SGI_I2C_FORCE_IDLE);
for (i = 0; i < adap->xfer_timeout; i++) {
if ((get_control() & SGI_I2C_NOT_IDLE) == 0)
goto out;
udelay(1);
}
return -ETIMEDOUT;
out:
if (get_control() & SGI_I2C_BUS_ERR)
return -EIO;
return 0;
}
static int do_address(struct i2c_algo_sgi_data *adap, unsigned int addr,
int rd)
{
if (rd)
set_control(SGI_I2C_NOT_IDLE);
/* Check if bus is idle, eventually force it to do so */
if (get_control() & SGI_I2C_NOT_IDLE)
if (force_idle(adap))
return -EIO;
/* Write out the i2c chip address and specify operation */
set_control(SGI_I2C_HOLD_BUS | SGI_I2C_WRITE | SGI_I2C_NOT_IDLE);
if (rd)
addr |= 1;
write_data(addr);
if (wait_ack(adap))
return -EIO;
return 0;
}
static int i2c_read(struct i2c_algo_sgi_data *adap, unsigned char *buf,
unsigned int len)
{
int i;
set_control(SGI_I2C_HOLD_BUS | SGI_I2C_READ | SGI_I2C_NOT_IDLE);
for (i = 0; i < len; i++) {
if (wait_xfer_done(adap))
return -EIO;
buf[i] = read_data();
}
set_control(SGI_I2C_RELEASE_BUS | SGI_I2C_FORCE_IDLE);
return 0;
}
static int i2c_write(struct i2c_algo_sgi_data *adap, unsigned char *buf,
unsigned int len)
{
int i;
/* We are already in write state */
for (i = 0; i < len; i++) {
write_data(buf[i]);
if (wait_ack(adap))
return -EIO;
}
return 0;
}
static int sgi_xfer(struct i2c_adapter *i2c_adap, struct i2c_msg *msgs,
int num)
{
struct i2c_algo_sgi_data *adap = i2c_adap->algo_data;
struct i2c_msg *p;
int i, err = 0;
for (i = 0; !err && i < num; i++) {
p = &msgs[i];
err = do_address(adap, p->addr, p->flags & I2C_M_RD);
if (err || !p->len)
continue;
if (p->flags & I2C_M_RD)
err = i2c_read(adap, p->buf, p->len);
else
err = i2c_write(adap, p->buf, p->len);
}
return err;
}
static u32 sgi_func(struct i2c_adapter *adap)
{
return I2C_FUNC_SMBUS_EMUL;
}
static struct i2c_algorithm sgi_algo = {
.id = I2C_ALGO_SGI,
.master_xfer = sgi_xfer,
.functionality = sgi_func,
};
/*
* registering functions to load algorithms at runtime
*/
int i2c_sgi_add_bus(struct i2c_adapter *adap)
{
adap->id |= I2C_ALGO_SGI;
adap->algo = &sgi_algo;
return i2c_add_adapter(adap);
}
int i2c_sgi_del_bus(struct i2c_adapter *adap)
{
return i2c_del_adapter(adap);
}
EXPORT_SYMBOL(i2c_sgi_add_bus);
EXPORT_SYMBOL(i2c_sgi_del_bus);
MODULE_AUTHOR("Ladislav Michl <ladis@linux-mips.org>");
MODULE_DESCRIPTION("I2C-Bus SGI algorithm");
MODULE_LICENSE("GPL");
|
