dmi: clean-up dmi helper declarations
[linux-2.6/openmoko-kernel/knife-kernel.git] / drivers / i2c / algos / i2c-algo-sgi.c
blob6eaf145e1adae6f8c244f392d77dbba53c5a176c
1 /*
2 * i2c-algo-sgi.c: i2c driver algorithm used by the VINO (SGI Indy) and
3 * MACE (SGI O2) chips.
5 * This file is subject to the terms and conditions of the GNU General Public
6 * License version 2 as published by the Free Software Foundation.
8 * Copyright (C) 2003 Ladislav Michl <ladis@linux-mips.org>
9 */
11 #include <linux/kernel.h>
12 #include <linux/module.h>
13 #include <linux/init.h>
14 #include <linux/errno.h>
15 #include <linux/delay.h>
17 #include <linux/i2c.h>
18 #include <linux/i2c-algo-sgi.h>
21 #define SGI_I2C_FORCE_IDLE (0 << 0)
22 #define SGI_I2C_NOT_IDLE (1 << 0)
23 #define SGI_I2C_WRITE (0 << 1)
24 #define SGI_I2C_READ (1 << 1)
25 #define SGI_I2C_RELEASE_BUS (0 << 2)
26 #define SGI_I2C_HOLD_BUS (1 << 2)
27 #define SGI_I2C_XFER_DONE (0 << 4)
28 #define SGI_I2C_XFER_BUSY (1 << 4)
29 #define SGI_I2C_ACK (0 << 5)
30 #define SGI_I2C_NACK (1 << 5)
31 #define SGI_I2C_BUS_OK (0 << 7)
32 #define SGI_I2C_BUS_ERR (1 << 7)
34 #define get_control() adap->getctrl(adap->data)
35 #define set_control(val) adap->setctrl(adap->data, val)
36 #define read_data() adap->rdata(adap->data)
37 #define write_data(val) adap->wdata(adap->data, val)
40 static int wait_xfer_done(struct i2c_algo_sgi_data *adap)
42 int i;
44 for (i = 0; i < adap->xfer_timeout; i++) {
45 if ((get_control() & SGI_I2C_XFER_BUSY) == 0)
46 return 0;
47 udelay(1);
50 return -ETIMEDOUT;
53 static int wait_ack(struct i2c_algo_sgi_data *adap)
55 int i;
57 if (wait_xfer_done(adap))
58 return -ETIMEDOUT;
59 for (i = 0; i < adap->ack_timeout; i++) {
60 if ((get_control() & SGI_I2C_NACK) == 0)
61 return 0;
62 udelay(1);
65 return -ETIMEDOUT;
68 static int force_idle(struct i2c_algo_sgi_data *adap)
70 int i;
72 set_control(SGI_I2C_FORCE_IDLE);
73 for (i = 0; i < adap->xfer_timeout; i++) {
74 if ((get_control() & SGI_I2C_NOT_IDLE) == 0)
75 goto out;
76 udelay(1);
78 return -ETIMEDOUT;
79 out:
80 if (get_control() & SGI_I2C_BUS_ERR)
81 return -EIO;
82 return 0;
85 static int do_address(struct i2c_algo_sgi_data *adap, unsigned int addr,
86 int rd)
88 if (rd)
89 set_control(SGI_I2C_NOT_IDLE);
90 /* Check if bus is idle, eventually force it to do so */
91 if (get_control() & SGI_I2C_NOT_IDLE)
92 if (force_idle(adap))
93 return -EIO;
94 /* Write out the i2c chip address and specify operation */
95 set_control(SGI_I2C_HOLD_BUS | SGI_I2C_WRITE | SGI_I2C_NOT_IDLE);
96 if (rd)
97 addr |= 1;
98 write_data(addr);
99 if (wait_ack(adap))
100 return -EIO;
101 return 0;
104 static int i2c_read(struct i2c_algo_sgi_data *adap, unsigned char *buf,
105 unsigned int len)
107 int i;
109 set_control(SGI_I2C_HOLD_BUS | SGI_I2C_READ | SGI_I2C_NOT_IDLE);
110 for (i = 0; i < len; i++) {
111 if (wait_xfer_done(adap))
112 return -EIO;
113 buf[i] = read_data();
115 set_control(SGI_I2C_RELEASE_BUS | SGI_I2C_FORCE_IDLE);
117 return 0;
121 static int i2c_write(struct i2c_algo_sgi_data *adap, unsigned char *buf,
122 unsigned int len)
124 int i;
126 /* We are already in write state */
127 for (i = 0; i < len; i++) {
128 write_data(buf[i]);
129 if (wait_ack(adap))
130 return -EIO;
132 return 0;
135 static int sgi_xfer(struct i2c_adapter *i2c_adap, struct i2c_msg *msgs,
136 int num)
138 struct i2c_algo_sgi_data *adap = i2c_adap->algo_data;
139 struct i2c_msg *p;
140 int i, err = 0;
142 for (i = 0; !err && i < num; i++) {
143 p = &msgs[i];
144 err = do_address(adap, p->addr, p->flags & I2C_M_RD);
145 if (err || !p->len)
146 continue;
147 if (p->flags & I2C_M_RD)
148 err = i2c_read(adap, p->buf, p->len);
149 else
150 err = i2c_write(adap, p->buf, p->len);
153 return (err < 0) ? err : i;
156 static u32 sgi_func(struct i2c_adapter *adap)
158 return I2C_FUNC_SMBUS_EMUL;
161 static const struct i2c_algorithm sgi_algo = {
162 .master_xfer = sgi_xfer,
163 .functionality = sgi_func,
167 * registering functions to load algorithms at runtime
169 int i2c_sgi_add_bus(struct i2c_adapter *adap)
171 adap->algo = &sgi_algo;
173 return i2c_add_adapter(adap);
175 EXPORT_SYMBOL(i2c_sgi_add_bus);
177 MODULE_AUTHOR("Ladislav Michl <ladis@linux-mips.org>");
178 MODULE_DESCRIPTION("I2C-Bus SGI algorithm");
179 MODULE_LICENSE("GPL");