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
207
208
209
210
211
212
213
214
215
216
217
218
219
220
|
/*
* GPIO latch driver
*
* Copyright (C) 2014 Gabor Juhos <juhosg@openwrt.org>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published
* by the Free Software Foundation.
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/gpio.h>
#include <linux/slab.h>
#include <linux/platform_device.h>
#include <linux/platform_data/gpio-latch.h>
struct gpio_latch_chip {
struct gpio_chip gc;
struct mutex mutex;
struct mutex latch_mutex;
bool latch_enabled;
int le_gpio;
bool le_active_low;
int *gpios;
};
static inline struct gpio_latch_chip *to_gpio_latch_chip(struct gpio_chip *gc)
{
return container_of(gc, struct gpio_latch_chip, gc);
}
static void gpio_latch_lock(struct gpio_latch_chip *glc, bool enable)
{
mutex_lock(&glc->mutex);
if (enable)
glc->latch_enabled = true;
if (glc->latch_enabled)
mutex_lock(&glc->latch_mutex);
}
static void gpio_latch_unlock(struct gpio_latch_chip *glc, bool disable)
{
if (glc->latch_enabled)
mutex_unlock(&glc->latch_mutex);
if (disable)
glc->latch_enabled = true;
mutex_unlock(&glc->mutex);
}
static int
gpio_latch_get(struct gpio_chip *gc, unsigned offset)
{
struct gpio_latch_chip *glc = to_gpio_latch_chip(gc);
int ret;
gpio_latch_lock(glc, false);
ret = gpio_get_value(glc->gpios[offset]);
gpio_latch_unlock(glc, false);
return ret;
}
static void
gpio_latch_set(struct gpio_chip *gc, unsigned offset, int value)
{
struct gpio_latch_chip *glc = to_gpio_latch_chip(gc);
bool enable_latch = false;
bool disable_latch = false;
int gpio;
gpio = glc->gpios[offset];
if (gpio == glc->le_gpio) {
enable_latch = value ^ glc->le_active_low;
disable_latch = !enable_latch;
}
gpio_latch_lock(glc, enable_latch);
gpio_set_value(gpio, value);
gpio_latch_unlock(glc, disable_latch);
}
static int
gpio_latch_direction_input(struct gpio_chip *gc, unsigned offset)
{
struct gpio_latch_chip *glc = to_gpio_latch_chip(gc);
int ret;
gpio_latch_lock(glc, false);
ret = gpio_direction_input(glc->gpios[offset]);
gpio_latch_unlock(glc, false);
return ret;
}
static int
gpio_latch_direction_output(struct gpio_chip *gc, unsigned offset, int value)
{
struct gpio_latch_chip *glc = to_gpio_latch_chip(gc);
bool enable_latch = false;
bool disable_latch = false;
int gpio;
int ret;
gpio = glc->gpios[offset];
if (gpio == glc->le_gpio) {
enable_latch = value ^ glc->le_active_low;
disable_latch = !enable_latch;
}
gpio_latch_lock(glc, enable_latch);
ret = gpio_direction_output(gpio, value);
gpio_latch_unlock(glc, disable_latch);
return ret;
}
static int gpio_latch_probe(struct platform_device *pdev)
{
struct gpio_latch_chip *glc;
struct gpio_latch_platform_data *pdata;
struct gpio_chip *gc;
int size;
int ret;
int i;
pdata = dev_get_platdata(&pdev->dev);
if (!pdata)
return -EINVAL;
if (pdata->le_gpio_index >= pdata->num_gpios ||
!pdata->num_gpios ||
!pdata->gpios)
return -EINVAL;
for (i = 0; i < pdata->num_gpios; i++) {
int gpio = pdata->gpios[i];
ret = devm_gpio_request(&pdev->dev, gpio,
GPIO_LATCH_DRIVER_NAME);
if (ret)
return ret;
}
glc = devm_kzalloc(&pdev->dev, sizeof(*glc), GFP_KERNEL);
if (!glc)
return -ENOMEM;
mutex_init(&glc->mutex);
mutex_init(&glc->latch_mutex);
size = pdata->num_gpios * sizeof(glc->gpios[0]);
glc->gpios = devm_kzalloc(&pdev->dev, size , GFP_KERNEL);
if (!glc->gpios)
return -ENOMEM;
memcpy(glc->gpios, pdata->gpios, size);
glc->le_gpio = glc->gpios[pdata->le_gpio_index];
glc->le_active_low = pdata->le_active_low;
gc = &glc->gc;
gc->label = GPIO_LATCH_DRIVER_NAME;
gc->base = pdata->base;
gc->can_sleep = true;
gc->ngpio = pdata->num_gpios;
gc->get = gpio_latch_get;
gc->set = gpio_latch_set;
gc->direction_input = gpio_latch_direction_input,
gc->direction_output = gpio_latch_direction_output;
platform_set_drvdata(pdev, glc);
ret = gpiochip_add(&glc->gc);
if (ret)
return ret;
return 0;
}
static int gpio_latch_remove(struct platform_device *pdev)
{
struct gpio_latch_chip *glc = platform_get_drvdata(pdev);
gpiochip_remove(&glc->gc);
return 0;
}
static struct platform_driver gpio_latch_driver = {
.probe = gpio_latch_probe,
.remove = gpio_latch_remove,
.driver = {
.name = GPIO_LATCH_DRIVER_NAME,
.owner = THIS_MODULE,
},
};
static int __init gpio_latch_init(void)
{
return platform_driver_register(&gpio_latch_driver);
}
postcore_initcall(gpio_latch_init);
MODULE_DESCRIPTION("GPIO latch driver");
MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:" GPIO_LATCH_DRIVER_NAME);
|
