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1/*
2 * MC33880 high-side/low-side switch GPIO driver
3 * Copyright (c) 2009 Intel Corporation
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
17 */
18
19/* Supports:
20 * Freescale MC33880 high-side/low-side switch
21 */
22
23#include <linux/init.h>
24#include <linux/mutex.h>
25#include <linux/spi/spi.h>
26#include <linux/spi/mc33880.h>
27#include <linux/gpio.h>
28#include <linux/slab.h>
29#include <linux/module.h>
30
31#define DRIVER_NAME "mc33880"
32
33/*
34 * Pin configurations, see MAX7301 datasheet page 6
35 */
36#define PIN_CONFIG_MASK 0x03
37#define PIN_CONFIG_IN_PULLUP 0x03
38#define PIN_CONFIG_IN_WO_PULLUP 0x02
39#define PIN_CONFIG_OUT 0x01
40
41#define PIN_NUMBER 8
42
43
44/*
45 * Some registers must be read back to modify.
46 * To save time we cache them here in memory
47 */
48struct mc33880 {
49	struct mutex	lock;	/* protect from simultaneous accesses */
50	u8		port_config;
51	struct gpio_chip chip;
52	struct spi_device *spi;
53};
54
55static int mc33880_write_config(struct mc33880 *mc)
56{
57	return spi_write(mc->spi, &mc->port_config, sizeof(mc->port_config));
58}
59
60
61static int __mc33880_set(struct mc33880 *mc, unsigned offset, int value)
62{
63	if (value)
64		mc->port_config |= 1 << offset;
65	else
66		mc->port_config &= ~(1 << offset);
67
68	return mc33880_write_config(mc);
69}
70
71
72static void mc33880_set(struct gpio_chip *chip, unsigned offset, int value)
73{
74	struct mc33880 *mc = container_of(chip, struct mc33880, chip);
75
76	mutex_lock(&mc->lock);
77
78	__mc33880_set(mc, offset, value);
79
80	mutex_unlock(&mc->lock);
81}
82
83static int mc33880_probe(struct spi_device *spi)
84{
85	struct mc33880 *mc;
86	struct mc33880_platform_data *pdata;
87	int ret;
88
89	pdata = dev_get_platdata(&spi->dev);
90	if (!pdata || !pdata->base) {
91		dev_dbg(&spi->dev, "incorrect or missing platform data\n");
92		return -EINVAL;
93	}
94
95	/*
96	 * bits_per_word cannot be configured in platform data
97	 */
98	spi->bits_per_word = 8;
99
100	ret = spi_setup(spi);
101	if (ret < 0)
102		return ret;
103
104	mc = devm_kzalloc(&spi->dev, sizeof(struct mc33880), GFP_KERNEL);
105	if (!mc)
106		return -ENOMEM;
107
108	mutex_init(&mc->lock);
109
110	spi_set_drvdata(spi, mc);
111
112	mc->spi = spi;
113
114	mc->chip.label = DRIVER_NAME,
115	mc->chip.set = mc33880_set;
116	mc->chip.base = pdata->base;
117	mc->chip.ngpio = PIN_NUMBER;
118	mc->chip.can_sleep = true;
119	mc->chip.dev = &spi->dev;
120	mc->chip.owner = THIS_MODULE;
121
122	mc->port_config = 0x00;
123	/* write twice, because during initialisation the first setting
124	 * is just for testing SPI communication, and the second is the
125	 * "real" configuration
126	 */
127	ret = mc33880_write_config(mc);
128	mc->port_config = 0x00;
129	if (!ret)
130		ret = mc33880_write_config(mc);
131
132	if (ret) {
133		dev_err(&spi->dev, "Failed writing to " DRIVER_NAME ": %d\n",
134			ret);
135		goto exit_destroy;
136	}
137
138	ret = gpiochip_add(&mc->chip);
139	if (ret)
140		goto exit_destroy;
141
142	return ret;
143
144exit_destroy:
145	mutex_destroy(&mc->lock);
146	return ret;
147}
148
149static int mc33880_remove(struct spi_device *spi)
150{
151	struct mc33880 *mc;
152
153	mc = spi_get_drvdata(spi);
154	if (mc == NULL)
155		return -ENODEV;
156
157	gpiochip_remove(&mc->chip);
158	mutex_destroy(&mc->lock);
159
160	return 0;
161}
162
163static struct spi_driver mc33880_driver = {
164	.driver = {
165		.name		= DRIVER_NAME,
166		.owner		= THIS_MODULE,
167	},
168	.probe		= mc33880_probe,
169	.remove		= mc33880_remove,
170};
171
172static int __init mc33880_init(void)
173{
174	return spi_register_driver(&mc33880_driver);
175}
176/* register after spi postcore initcall and before
177 * subsys initcalls that may rely on these GPIOs
178 */
179subsys_initcall(mc33880_init);
180
181static void __exit mc33880_exit(void)
182{
183	spi_unregister_driver(&mc33880_driver);
184}
185module_exit(mc33880_exit);
186
187MODULE_AUTHOR("Mocean Laboratories <info@mocean-labs.com>");
188MODULE_LICENSE("GPL v2");
189
190