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Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * i2c-algo-sgi.c: i2c driver algorithms for SGI adapters.
3 *
4 * This file is subject to the terms and conditions of the GNU General Public
5 * License version 2 as published by the Free Software Foundation.
6 *
7 * Copyright (C) 2003 Ladislav Michl <ladis@linux-mips.org>
8 */
9
10#include <linux/kernel.h>
11#include <linux/module.h>
12#include <linux/init.h>
13#include <linux/errno.h>
14#include <linux/delay.h>
15
16#include <linux/i2c.h>
17#include <linux/i2c-algo-sgi.h>
18
19
20#define SGI_I2C_FORCE_IDLE (0 << 0)
21#define SGI_I2C_NOT_IDLE (1 << 0)
22#define SGI_I2C_WRITE (0 << 1)
23#define SGI_I2C_READ (1 << 1)
24#define SGI_I2C_RELEASE_BUS (0 << 2)
25#define SGI_I2C_HOLD_BUS (1 << 2)
26#define SGI_I2C_XFER_DONE (0 << 4)
27#define SGI_I2C_XFER_BUSY (1 << 4)
28#define SGI_I2C_ACK (0 << 5)
29#define SGI_I2C_NACK (1 << 5)
30#define SGI_I2C_BUS_OK (0 << 7)
31#define SGI_I2C_BUS_ERR (1 << 7)
32
33#define get_control() adap->getctrl(adap->data)
34#define set_control(val) adap->setctrl(adap->data, val)
35#define read_data() adap->rdata(adap->data)
36#define write_data(val) adap->wdata(adap->data, val)
37
38
39static int wait_xfer_done(struct i2c_algo_sgi_data *adap)
40{
41 int i;
42
43 for (i = 0; i < adap->xfer_timeout; i++) {
44 if ((get_control() & SGI_I2C_XFER_BUSY) == 0)
45 return 0;
46 udelay(1);
47 }
48
49 return -ETIMEDOUT;
50}
51
52static int wait_ack(struct i2c_algo_sgi_data *adap)
53{
54 int i;
55
56 if (wait_xfer_done(adap))
57 return -ETIMEDOUT;
58 for (i = 0; i < adap->ack_timeout; i++) {
59 if ((get_control() & SGI_I2C_NACK) == 0)
60 return 0;
61 udelay(1);
62 }
63
64 return -ETIMEDOUT;
65}
66
67static int force_idle(struct i2c_algo_sgi_data *adap)
68{
69 int i;
70
71 set_control(SGI_I2C_FORCE_IDLE);
72 for (i = 0; i < adap->xfer_timeout; i++) {
73 if ((get_control() & SGI_I2C_NOT_IDLE) == 0)
74 goto out;
75 udelay(1);
76 }
77 return -ETIMEDOUT;
78out:
79 if (get_control() & SGI_I2C_BUS_ERR)
80 return -EIO;
81 return 0;
82}
83
84static int do_address(struct i2c_algo_sgi_data *adap, unsigned int addr,
85 int rd)
86{
87 if (rd)
88 set_control(SGI_I2C_NOT_IDLE);
89 /* Check if bus is idle, eventually force it to do so */
90 if (get_control() & SGI_I2C_NOT_IDLE)
91 if (force_idle(adap))
92 return -EIO;
93 /* Write out the i2c chip address and specify operation */
94 set_control(SGI_I2C_HOLD_BUS | SGI_I2C_WRITE | SGI_I2C_NOT_IDLE);
95 if (rd)
96 addr |= 1;
97 write_data(addr);
98 if (wait_ack(adap))
99 return -EIO;
100 return 0;
101}
102
103static int i2c_read(struct i2c_algo_sgi_data *adap, unsigned char *buf,
104 unsigned int len)
105{
106 int i;
107
108 set_control(SGI_I2C_HOLD_BUS | SGI_I2C_READ | SGI_I2C_NOT_IDLE);
109 for (i = 0; i < len; i++) {
110 if (wait_xfer_done(adap))
111 return -EIO;
112 buf[i] = read_data();
113 }
114 set_control(SGI_I2C_RELEASE_BUS | SGI_I2C_FORCE_IDLE);
115
116 return 0;
117
118}
119
120static int i2c_write(struct i2c_algo_sgi_data *adap, unsigned char *buf,
121 unsigned int len)
122{
123 int i;
124
125 /* We are already in write state */
126 for (i = 0; i < len; i++) {
127 write_data(buf[i]);
128 if (wait_ack(adap))
129 return -EIO;
130 }
131 return 0;
132}
133
134static int sgi_xfer(struct i2c_adapter *i2c_adap, struct i2c_msg *msgs,
135 int num)
136{
137 struct i2c_algo_sgi_data *adap = i2c_adap->algo_data;
138 struct i2c_msg *p;
139 int i, err = 0;
140
141 for (i = 0; !err && i < num; i++) {
142 p = &msgs[i];
143 err = do_address(adap, p->addr, p->flags & I2C_M_RD);
144 if (err || !p->len)
145 continue;
146 if (p->flags & I2C_M_RD)
147 err = i2c_read(adap, p->buf, p->len);
148 else
149 err = i2c_write(adap, p->buf, p->len);
150 }
151
152 return (err < 0) ? err : i;
153}
154
155static u32 sgi_func(struct i2c_adapter *adap)
156{
157 return I2C_FUNC_SMBUS_EMUL;
158}
159
160static struct i2c_algorithm sgi_algo = {
161 .master_xfer = sgi_xfer,
162 .functionality = sgi_func,
163};
164
165/*
166 * registering functions to load algorithms at runtime
167 */
168int i2c_sgi_add_bus(struct i2c_adapter *adap)
169{
170 adap->algo = &sgi_algo;
171
172 return i2c_add_adapter(adap);
173}
174
175
176int i2c_sgi_del_bus(struct i2c_adapter *adap)
177{
178 return i2c_del_adapter(adap);
179}
180
181EXPORT_SYMBOL(i2c_sgi_add_bus);
182EXPORT_SYMBOL(i2c_sgi_del_bus);
183
184MODULE_AUTHOR("Ladislav Michl <ladis@linux-mips.org>");
185MODULE_DESCRIPTION("I2C-Bus SGI algorithm");
186MODULE_LICENSE("GPL");