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
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
|
// SPDX-License-Identifier: GPL-2.0+
/*
* simple parameterized no-irq of_driven i2c->gpio expander,
* cut down from gpio-pcf857x.c to be totally device-tree driven.
*
* Suitable for any "memory-like" device, where a 1-byte i2c read yields data
* which can safely be written back, possibly with a bit changed, with the
* effect of changing only the output level of that bit's GPIO pin.
*
* Copyright (C) 2016 Cavium Inc.
* Copyright (C) 2019 Marvell International Ltd.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/gpio.h>
#include <linux/i2c.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
struct gpio_i2c_platform_data {
unsigned int i2c_addr;
unsigned int pins;
};
static const struct of_device_id gpio_i2c_of_table[] = {
{ .compatible = "gpio-i2c" },
{ }
};
MODULE_DEVICE_TABLE(of, gpio_i2c_of_table);
struct gpio_i2c {
unsigned int i2c_addr;
struct gpio_chip chip;
struct i2c_client *client;
struct mutex lock; /* protect 'out' */
u8 out[]; /* software latch */
};
/*-------------------------------------------------------------------------*/
static int gpio_i2c_get(struct gpio_chip *chip, unsigned int offset)
{
struct gpio_i2c *gpio = container_of(chip, struct gpio_i2c, chip);
int value;
unsigned int byte = (offset >> 3);
unsigned int bit = (offset & 7);
mutex_lock(&gpio->lock);
value = i2c_smbus_read_byte_data(gpio->client, byte);
mutex_unlock(&gpio->lock);
return (value < 0) ? 0 : ((value >> bit) & 1);
}
static int gpio_i2c_output(struct gpio_chip *chip,
unsigned int offset, int value)
{
struct gpio_i2c *gpio = container_of(chip, struct gpio_i2c, chip);
unsigned int byte = (offset >> 3);
unsigned int bit = (offset & 7);
unsigned int mask = (1 << bit);
int status;
u8 was;
mutex_lock(&gpio->lock);
was = i2c_smbus_read_byte_data(gpio->client, byte);
if (value)
was |= mask;
else
was &= ~mask;
status = i2c_smbus_write_byte_data(gpio->client, byte, was);
gpio->out[byte] = was;
mutex_unlock(&gpio->lock);
return status;
}
static void gpio_i2c_set(struct gpio_chip *chip, unsigned int offset, int value)
{
gpio_i2c_output(chip, offset, value);
}
/* for open-drain: set as input by letting output go high */
static int gpio_i2c_input(struct gpio_chip *chip, unsigned int offset)
{
return gpio_i2c_output(chip, offset, 1);
}
/*-------------------------------------------------------------------------*/
static int gpio_i2c_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct gpio_i2c_platform_data *pdata = dev_get_platdata(&client->dev);
struct device_node *np = client->dev.of_node;
struct gpio_i2c *gpio;
u32 pins;
u32 i2c_addr;
int status;
if (np) {
status = of_property_read_u32(np, "reg", &i2c_addr);
if (status < 0) {
dev_dbg(&client->dev, "missing reg property\n");
return status;
}
status = of_property_read_u32(np, "ngpios", &pins);
if (status < 0) {
dev_dbg(&client->dev, "missing ngpios property\n");
return status;
}
} else if (pdata) {
i2c_addr = pdata->i2c_addr;
pins = pdata->pins;
} else {
dev_dbg(&client->dev, "no platform data\n");
return -EPROBE_DEFER;
}
/* Allocate, initialize, and register this gpio_chip. */
gpio = devm_kzalloc(&client->dev,
sizeof(*gpio) + (pins + 7) / 8, GFP_KERNEL);
if (!gpio)
return -ENOMEM;
mutex_init(&gpio->lock);
gpio->i2c_addr = i2c_addr;
gpio->chip.base = -1;
gpio->chip.can_sleep = true;
gpio->chip.parent = &client->dev;
gpio->chip.owner = THIS_MODULE;
gpio->chip.get = gpio_i2c_get;
gpio->chip.set = gpio_i2c_set;
gpio->chip.direction_input = gpio_i2c_input;
gpio->chip.direction_output = gpio_i2c_output;
gpio->chip.ngpio = pins;
gpio->chip.label = client->name;
gpio->client = client;
gpio->client->addr = i2c_addr;
i2c_set_clientdata(client, gpio);
status = gpiochip_add(&gpio->chip);
if (status < 0)
goto fail;
dev_info(&client->dev, "probed\n");
return 0;
fail:
dev_dbg(&client->dev, "probe error %d for '%s'\n", status,
client->name);
return status;
}
static int gpio_i2c_remove(struct i2c_client *client)
{
struct gpio_i2c *gpio = i2c_get_clientdata(client);
int status = 0;
gpiochip_remove(&gpio->chip);
return status;
}
/* this must _exist_ for i2c_device_probe() to call our probe, may be empty */
static struct i2c_device_id empty_id_table[] = {
{ },
};
MODULE_DEVICE_TABLE(i2c, empty_id_table);
static struct i2c_driver gpio_i2c_driver = {
.driver = {
.name = "gpio-i2c",
.of_match_table = of_match_ptr(gpio_i2c_of_table),
},
.probe = gpio_i2c_probe,
.remove = gpio_i2c_remove,
.id_table = empty_id_table,
};
module_i2c_driver(gpio_i2c_driver);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("David Brownell");
MODULE_AUTHOR("Peter Swain <pswain@cavium.com>");
/*
* arguably this name defies convention, but correct(?) alias has been
* taken by the inverse function in
* drivers/i2c/busses/i2c-gpio.c:MODULE_ALIAS("platform:i2c-gpio");
*/
MODULE_ALIAS("platform:gpio-i2c");
|
