summaryrefslogtreecommitdiff
path: root/drivers/i2c/busses/i2c-ixp2000.c
blob: ec943cad23147524c917c1fe5d93de97ad6e90c6 (plain)
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
/*
 * drivers/i2c/busses/i2c-ixp2000.c
 *
 * I2C adapter for IXP2000 systems using GPIOs for I2C bus
 *
 * Author: Deepak Saxena <dsaxena@plexity.net>
 * Based on IXDP2400 code by: Naeem M. Afzal <naeem.m.afzal@intel.com>
 * Made generic by: Jeff Daly <jeffrey.daly@intel.com>
 *
 * Copyright (c) 2003-2004 MontaVista Software Inc.
 *
 * This file is licensed under  the terms of the GNU General Public 
 * License version 2. This program is licensed "as is" without any 
 * warranty of any kind, whether express or implied.
 *
 * From Jeff Daly:
 *
 * I2C adapter driver for Intel IXDP2xxx platforms. This should work for any
 * IXP2000 platform if it uses the HW GPIO in the same manner.  Basically, 
 * SDA and SCL GPIOs have external pullups.  Setting the respective GPIO to 
 * an input will make the signal a '1' via the pullup.  Setting them to 
 * outputs will pull them down. 
 *
 * The GPIOs are open drain signals and are used as configuration strap inputs
 * during power-up so there's generally a buffer on the board that needs to be 
 * 'enabled' to drive the GPIOs.
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/i2c-algo-bit.h>

#include <asm/hardware.h>	/* Pick up IXP42000-specific bits */

static inline int ixp2000_scl_pin(void *data)
{
	return ((struct ixp2000_i2c_pins*)data)->scl_pin;
}

static inline int ixp2000_sda_pin(void *data)
{
	return ((struct ixp2000_i2c_pins*)data)->sda_pin;
}


static void ixp2000_bit_setscl(void *data, int val)
{
	int i = 5000;

	if (val) {
		gpio_line_config(ixp2000_scl_pin(data), GPIO_IN);
		while(!gpio_line_get(ixp2000_scl_pin(data)) && i--);
	} else {
		gpio_line_config(ixp2000_scl_pin(data), GPIO_OUT);
	}
}

static void ixp2000_bit_setsda(void *data, int val)
{
	if (val) {
		gpio_line_config(ixp2000_sda_pin(data), GPIO_IN);
	} else {
		gpio_line_config(ixp2000_sda_pin(data), GPIO_OUT);
	}
}

static int ixp2000_bit_getscl(void *data)
{
	return gpio_line_get(ixp2000_scl_pin(data));
}

static int ixp2000_bit_getsda(void *data)
{
	return gpio_line_get(ixp2000_sda_pin(data));
}

struct ixp2000_i2c_data {
	struct ixp2000_i2c_pins *gpio_pins;
	struct i2c_adapter adapter;
	struct i2c_algo_bit_data algo_data;
};

static int ixp2000_i2c_remove(struct device *dev)
{
	struct platform_device *plat_dev = to_platform_device(dev);
	struct ixp2000_i2c_data *drv_data = dev_get_drvdata(&plat_dev->dev);

	dev_set_drvdata(&plat_dev->dev, NULL);

	i2c_bit_del_bus(&drv_data->adapter);

	kfree(drv_data);

	return 0;
}

static int ixp2000_i2c_probe(struct device *dev)
{
	int err;
	struct platform_device *plat_dev = to_platform_device(dev);
	struct ixp2000_i2c_pins *gpio = plat_dev->dev.platform_data;
	struct ixp2000_i2c_data *drv_data = 
		kmalloc(sizeof(struct ixp2000_i2c_data), GFP_KERNEL);

	if (!drv_data)
		return -ENOMEM;
	memzero(drv_data, sizeof(*drv_data));
	drv_data->gpio_pins = gpio;

	drv_data->algo_data.data = gpio;
	drv_data->algo_data.setsda = ixp2000_bit_setsda;
	drv_data->algo_data.setscl = ixp2000_bit_setscl;
	drv_data->algo_data.getsda = ixp2000_bit_getsda;
	drv_data->algo_data.getscl = ixp2000_bit_getscl;
	drv_data->algo_data.udelay = 6;
	drv_data->algo_data.mdelay = 6;
	drv_data->algo_data.timeout = 100;

	drv_data->adapter.id = I2C_HW_B_IXP2000,
	drv_data->adapter.algo_data = &drv_data->algo_data,

	drv_data->adapter.dev.parent = &plat_dev->dev;

	gpio_line_config(gpio->sda_pin, GPIO_IN);
	gpio_line_config(gpio->scl_pin, GPIO_IN);
	gpio_line_set(gpio->scl_pin, 0);
	gpio_line_set(gpio->sda_pin, 0);

	if ((err = i2c_bit_add_bus(&drv_data->adapter)) != 0) {
		dev_err(dev, "Could not install, error %d\n", err);
		kfree(drv_data);
		return err;
	} 

	dev_set_drvdata(&plat_dev->dev, drv_data);

	return 0;
}

static struct device_driver ixp2000_i2c_driver = {
	.name		= "IXP2000-I2C",
	.bus		= &platform_bus_type,
	.probe		= ixp2000_i2c_probe,
	.remove		= ixp2000_i2c_remove,
};

static int __init ixp2000_i2c_init(void)
{
	return driver_register(&ixp2000_i2c_driver);
}

static void __exit ixp2000_i2c_exit(void)
{
	driver_unregister(&ixp2000_i2c_driver);
}

module_init(ixp2000_i2c_init);
module_exit(ixp2000_i2c_exit);

MODULE_AUTHOR ("Deepak Saxena <dsaxena@plexity.net>");
MODULE_DESCRIPTION("IXP2000 GPIO-based I2C bus driver");
MODULE_LICENSE("GPL");