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/drivers/i2c/algos/i2c-algo-sgi.c

https://bitbucket.org/evzijst/gittest
C | 189 lines | 143 code | 32 blank | 14 comment | 25 complexity | 33f7ce044063a5d21b3e684bea23ba2c MD5 | raw file
  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;
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	.name		= "SGI algorithm",
162	.id		= I2C_ALGO_SGI,
163	.master_xfer	= sgi_xfer,
164	.functionality	= sgi_func,
165};
166
167/* 
168 * registering functions to load algorithms at runtime 
169 */
170int i2c_sgi_add_bus(struct i2c_adapter *adap)
171{
172	adap->id |= sgi_algo.id;
173	adap->algo = &sgi_algo;
174
175	return i2c_add_adapter(adap);
176}
177
178
179int i2c_sgi_del_bus(struct i2c_adapter *adap)
180{
181	return i2c_del_adapter(adap);
182}
183
184EXPORT_SYMBOL(i2c_sgi_add_bus);
185EXPORT_SYMBOL(i2c_sgi_del_bus);
186
187MODULE_AUTHOR("Ladislav Michl <ladis@linux-mips.org>");
188MODULE_DESCRIPTION("I2C-Bus SGI algorithm");
189MODULE_LICENSE("GPL");