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#include <linux/module.h>
19
20struct gen_74x164_chip {
21	struct spi_device	*spi;
22	struct gpio_chip	gpio_chip;
23	struct mutex		lock;
24	u8			port_config;
25};
26
27static struct gen_74x164_chip *gpio_to_74x164_chip(struct gpio_chip *gc)
28{
29	return container_of(gc, struct gen_74x164_chip, gpio_chip);
30}
31
32static int __gen_74x164_write_config(struct gen_74x164_chip *chip)
33{
34	return spi_write(chip->spi,
35			 &chip->port_config, sizeof(chip->port_config));
36}
37
38static int gen_74x164_get_value(struct gpio_chip *gc, unsigned offset)
39{
40	struct gen_74x164_chip *chip = gpio_to_74x164_chip(gc);
41	int ret;
42
43	mutex_lock(&chip->lock);
44	ret = (chip->port_config >> offset) & 0x1;
45	mutex_unlock(&chip->lock);
46
47	return ret;
48}
49
50static void gen_74x164_set_value(struct gpio_chip *gc,
51		unsigned offset, int val)
52{
53	struct gen_74x164_chip *chip = gpio_to_74x164_chip(gc);
54
55	mutex_lock(&chip->lock);
56	if (val)
57		chip->port_config |= (1 << offset);
58	else
59		chip->port_config &= ~(1 << offset);
60
61	__gen_74x164_write_config(chip);
62	mutex_unlock(&chip->lock);
63}
64
65static int gen_74x164_direction_output(struct gpio_chip *gc,
66		unsigned offset, int val)
67{
68	gen_74x164_set_value(gc, offset, val);
69	return 0;
70}
71
72static int __devinit gen_74x164_probe(struct spi_device *spi)
73{
74	struct gen_74x164_chip *chip;
75	struct gen_74x164_chip_platform_data *pdata;
76	int ret;
77
78	pdata = spi->dev.platform_data;
79	if (!pdata || !pdata->base) {
80		dev_dbg(&spi->dev, "incorrect or missing platform data\n");
81		return -EINVAL;
82	}
83
84	/*
85	 * bits_per_word cannot be configured in platform data
86	 */
87	spi->bits_per_word = 8;
88
89	ret = spi_setup(spi);
90	if (ret < 0)
91		return ret;
92
93	chip = kzalloc(sizeof(*chip), GFP_KERNEL);
94	if (!chip)
95		return -ENOMEM;
96
97	mutex_init(&chip->lock);
98
99	dev_set_drvdata(&spi->dev, chip);
100
101	chip->spi = spi;
102
103	chip->gpio_chip.label = spi->modalias;
104	chip->gpio_chip.direction_output = gen_74x164_direction_output;
105	chip->gpio_chip.get = gen_74x164_get_value;
106	chip->gpio_chip.set = gen_74x164_set_value;
107	chip->gpio_chip.base = pdata->base;
108	chip->gpio_chip.ngpio = 8;
109	chip->gpio_chip.can_sleep = 1;
110	chip->gpio_chip.dev = &spi->dev;
111	chip->gpio_chip.owner = THIS_MODULE;
112
113	ret = __gen_74x164_write_config(chip);
114	if (ret) {
115		dev_err(&spi->dev, "Failed writing: %d\n", ret);
116		goto exit_destroy;
117	}
118
119	ret = gpiochip_add(&chip->gpio_chip);
120	if (ret)
121		goto exit_destroy;
122
123	return ret;
124
125exit_destroy:
126	dev_set_drvdata(&spi->dev, NULL);
127	mutex_destroy(&chip->lock);
128	kfree(chip);
129	return ret;
130}
131
132static int __devexit gen_74x164_remove(struct spi_device *spi)
133{
134	struct gen_74x164_chip *chip;
135	int ret;
136
137	chip = dev_get_drvdata(&spi->dev);
138	if (chip == NULL)
139		return -ENODEV;
140
141	dev_set_drvdata(&spi->dev, NULL);
142
143	ret = gpiochip_remove(&chip->gpio_chip);
144	if (!ret) {
145		mutex_destroy(&chip->lock);
146		kfree(chip);
147	} else
148		dev_err(&spi->dev, "Failed to remove the GPIO controller: %d\n",
149				ret);
150
151	return ret;
152}
153
154static struct spi_driver gen_74x164_driver = {
155	.driver = {
156		.name		= "74x164",
157		.owner		= THIS_MODULE,
158	},
159	.probe		= gen_74x164_probe,
160	.remove		= __devexit_p(gen_74x164_remove),
161};
162
163static int __init gen_74x164_init(void)
164{
165	return spi_register_driver(&gen_74x164_driver);
166}
167subsys_initcall(gen_74x164_init);
168
169static void __exit gen_74x164_exit(void)
170{
171	spi_unregister_driver(&gen_74x164_driver);
172}
173module_exit(gen_74x164_exit);
174
175MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
176MODULE_AUTHOR("Miguel Gaio <miguel.gaio@efixo.com>");
177MODULE_DESCRIPTION("GPIO expander driver for 74X164 8-bits shift register");
178MODULE_LICENSE("GPL v2");
179