tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * 74Hx164 - Generic serial-in/parallel-out 8-bits shift register GPIO driver
3 *
4 * Copyright (C) 2010 Gabor Juhos <juhosg@openwrt.org>
5 * Copyright (C) 2010 Miguel Gaio <miguel.gaio@efixo.com>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 */
11
12#include <linux/init.h>
13#include <linux/mutex.h>
14#include <linux/spi/spi.h>
15#include <linux/spi/74x164.h>
16#include <linux/gpio.h>
17#include <linux/slab.h>
18
19#define GEN_74X164_GPIO_COUNT 8
20
21
22struct gen_74x164_chip {
23 struct spi_device *spi;
24 struct gpio_chip gpio_chip;
25 struct mutex lock;
26 u8 port_config;
27};
28
29static void gen_74x164_set_value(struct gpio_chip *, unsigned, int);
30
31static struct gen_74x164_chip *gpio_to_chip(struct gpio_chip *gc)
32{
33 return container_of(gc, struct gen_74x164_chip, gpio_chip);
34}
35
36static int __gen_74x164_write_config(struct gen_74x164_chip *chip)
37{
38 return spi_write(chip->spi,
39 &chip->port_config, sizeof(chip->port_config));
40}
41
42static int gen_74x164_direction_output(struct gpio_chip *gc,
43 unsigned offset, int val)
44{
45 gen_74x164_set_value(gc, offset, val);
46 return 0;
47}
48
49static int gen_74x164_get_value(struct gpio_chip *gc, unsigned offset)
50{
51 struct gen_74x164_chip *chip = gpio_to_chip(gc);
52 int ret;
53
54 mutex_lock(&chip->lock);
55 ret = (chip->port_config >> offset) & 0x1;
56 mutex_unlock(&chip->lock);
57
58 return ret;
59}
60
61static void gen_74x164_set_value(struct gpio_chip *gc,
62 unsigned offset, int val)
63{
64 struct gen_74x164_chip *chip = gpio_to_chip(gc);
65
66 mutex_lock(&chip->lock);
67 if (val)
68 chip->port_config |= (1 << offset);
69 else
70 chip->port_config &= ~(1 << offset);
71
72 __gen_74x164_write_config(chip);
73 mutex_unlock(&chip->lock);
74}
75
76static int __devinit gen_74x164_probe(struct spi_device *spi)
77{
78 struct gen_74x164_chip *chip;
79 struct gen_74x164_chip_platform_data *pdata;
80 int ret;
81
82 pdata = spi->dev.platform_data;
83 if (!pdata || !pdata->base) {
84 dev_dbg(&spi->dev, "incorrect or missing platform data\n");
85 return -EINVAL;
86 }
87
88 /*
89 * bits_per_word cannot be configured in platform data
90 */
91 spi->bits_per_word = 8;
92
93 ret = spi_setup(spi);
94 if (ret < 0)
95 return ret;
96
97 chip = kzalloc(sizeof(*chip), GFP_KERNEL);
98 if (!chip)
99 return -ENOMEM;
100
101 mutex_init(&chip->lock);
102
103 dev_set_drvdata(&spi->dev, chip);
104
105 chip->spi = spi;
106
107 chip->gpio_chip.label = GEN_74X164_DRIVER_NAME,
108 chip->gpio_chip.direction_output = gen_74x164_direction_output;
109 chip->gpio_chip.get = gen_74x164_get_value;
110 chip->gpio_chip.set = gen_74x164_set_value;
111 chip->gpio_chip.base = pdata->base;
112 chip->gpio_chip.ngpio = GEN_74X164_GPIO_COUNT;
113 chip->gpio_chip.can_sleep = 1;
114 chip->gpio_chip.dev = &spi->dev;
115 chip->gpio_chip.owner = THIS_MODULE;
116
117 ret = __gen_74x164_write_config(chip);
118 if (ret) {
119 dev_err(&spi->dev, "Failed writing: %d\n", ret);
120 goto exit_destroy;
121 }
122
123 ret = gpiochip_add(&chip->gpio_chip);
124 if (ret)
125 goto exit_destroy;
126
127 return ret;
128
129exit_destroy:
130 dev_set_drvdata(&spi->dev, NULL);
131 mutex_destroy(&chip->lock);
132 kfree(chip);
133 return ret;
134}
135
136static int __devexit gen_74x164_remove(struct spi_device *spi)
137{
138 struct gen_74x164_chip *chip;
139 int ret;
140
141 chip = dev_get_drvdata(&spi->dev);
142 if (chip == NULL)
143 return -ENODEV;
144
145 dev_set_drvdata(&spi->dev, NULL);
146
147 ret = gpiochip_remove(&chip->gpio_chip);
148 if (!ret) {
149 mutex_destroy(&chip->lock);
150 kfree(chip);
151 } else
152 dev_err(&spi->dev, "Failed to remove the GPIO controller: %d\n",
153 ret);
154
155 return ret;
156}
157
158static struct spi_driver gen_74x164_driver = {
159 .driver = {
160 .name = GEN_74X164_DRIVER_NAME,
161 .owner = THIS_MODULE,
162 },
163 .probe = gen_74x164_probe,
164 .remove = __devexit_p(gen_74x164_remove),
165};
166
167static int __init gen_74x164_init(void)
168{
169 return spi_register_driver(&gen_74x164_driver);
170}
171subsys_initcall(gen_74x164_init);
172
173static void __exit gen_74x164_exit(void)
174{
175 spi_unregister_driver(&gen_74x164_driver);
176}
177module_exit(gen_74x164_exit);
178
179MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
180MODULE_AUTHOR("Miguel Gaio <miguel.gaio@efixo.com>");
181MODULE_DESCRIPTION("GPIO expander driver for 74X164 8-bits shift register");
182MODULE_LICENSE("GPL v2");