Root/drivers/gpio/gpio-max730x.c

1/**
2 * Copyright (C) 2006 Juergen Beisert, Pengutronix
3 * Copyright (C) 2008 Guennadi Liakhovetski, Pengutronix
4 * Copyright (C) 2009 Wolfram Sang, Pengutronix
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 * The Maxim MAX7300/1 device is an I2C/SPI driven GPIO expander. There are
11 * 28 GPIOs. 8 of them can trigger an interrupt. See datasheet for more
12 * details
13 * Note:
14 * - DIN must be stable at the rising edge of clock.
15 * - when writing:
16 * - always clock in 16 clocks at once
17 * - at DIN: D15 first, D0 last
18 * - D0..D7 = databyte, D8..D14 = commandbyte
19 * - D15 = low -> write command
20 * - when reading
21 * - always clock in 16 clocks at once
22 * - at DIN: D15 first, D0 last
23 * - D0..D7 = dummy, D8..D14 = register address
24 * - D15 = high -> read command
25 * - raise CS and assert it again
26 * - always clock in 16 clocks at once
27 * - at DOUT: D15 first, D0 last
28 * - D0..D7 contains the data from the first cycle
29 *
30 * The driver exports a standard gpiochip interface
31 */
32
33#include <linux/module.h>
34#include <linux/init.h>
35#include <linux/platform_device.h>
36#include <linux/mutex.h>
37#include <linux/spi/max7301.h>
38#include <linux/gpio.h>
39#include <linux/slab.h>
40
41/*
42 * Pin configurations, see MAX7301 datasheet page 6
43 */
44#define PIN_CONFIG_MASK 0x03
45#define PIN_CONFIG_IN_PULLUP 0x03
46#define PIN_CONFIG_IN_WO_PULLUP 0x02
47#define PIN_CONFIG_OUT 0x01
48
49#define PIN_NUMBER 28
50
51static int max7301_direction_input(struct gpio_chip *chip, unsigned offset)
52{
53    struct max7301 *ts = container_of(chip, struct max7301, chip);
54    u8 *config;
55    u8 offset_bits, pin_config;
56    int ret;
57
58    /* First 4 pins are unused in the controller */
59    offset += 4;
60    offset_bits = (offset & 3) << 1;
61
62    config = &ts->port_config[offset >> 2];
63
64    if (ts->input_pullup_active & BIT(offset))
65        pin_config = PIN_CONFIG_IN_PULLUP;
66    else
67        pin_config = PIN_CONFIG_IN_WO_PULLUP;
68
69    mutex_lock(&ts->lock);
70
71    *config = (*config & ~(PIN_CONFIG_MASK << offset_bits))
72               | (pin_config << offset_bits);
73
74    ret = ts->write(ts->dev, 0x08 + (offset >> 2), *config);
75
76    mutex_unlock(&ts->lock);
77
78    return ret;
79}
80
81static int __max7301_set(struct max7301 *ts, unsigned offset, int value)
82{
83    if (value) {
84        ts->out_level |= 1 << offset;
85        return ts->write(ts->dev, 0x20 + offset, 0x01);
86    } else {
87        ts->out_level &= ~(1 << offset);
88        return ts->write(ts->dev, 0x20 + offset, 0x00);
89    }
90}
91
92static int max7301_direction_output(struct gpio_chip *chip, unsigned offset,
93                    int value)
94{
95    struct max7301 *ts = container_of(chip, struct max7301, chip);
96    u8 *config;
97    u8 offset_bits;
98    int ret;
99
100    /* First 4 pins are unused in the controller */
101    offset += 4;
102    offset_bits = (offset & 3) << 1;
103
104    config = &ts->port_config[offset >> 2];
105
106    mutex_lock(&ts->lock);
107
108    *config = (*config & ~(PIN_CONFIG_MASK << offset_bits))
109               | (PIN_CONFIG_OUT << offset_bits);
110
111    ret = __max7301_set(ts, offset, value);
112
113    if (!ret)
114        ret = ts->write(ts->dev, 0x08 + (offset >> 2), *config);
115
116    mutex_unlock(&ts->lock);
117
118    return ret;
119}
120
121static int max7301_get(struct gpio_chip *chip, unsigned offset)
122{
123    struct max7301 *ts = container_of(chip, struct max7301, chip);
124    int config, level = -EINVAL;
125
126    /* First 4 pins are unused in the controller */
127    offset += 4;
128
129    mutex_lock(&ts->lock);
130
131    config = (ts->port_config[offset >> 2] >> ((offset & 3) << 1))
132            & PIN_CONFIG_MASK;
133
134    switch (config) {
135    case PIN_CONFIG_OUT:
136        /* Output: return cached level */
137        level = !!(ts->out_level & (1 << offset));
138        break;
139    case PIN_CONFIG_IN_WO_PULLUP:
140    case PIN_CONFIG_IN_PULLUP:
141        /* Input: read out */
142        level = ts->read(ts->dev, 0x20 + offset) & 0x01;
143    }
144    mutex_unlock(&ts->lock);
145
146    return level;
147}
148
149static void max7301_set(struct gpio_chip *chip, unsigned offset, int value)
150{
151    struct max7301 *ts = container_of(chip, struct max7301, chip);
152
153    /* First 4 pins are unused in the controller */
154    offset += 4;
155
156    mutex_lock(&ts->lock);
157
158    __max7301_set(ts, offset, value);
159
160    mutex_unlock(&ts->lock);
161}
162
163int __devinit __max730x_probe(struct max7301 *ts)
164{
165    struct device *dev = ts->dev;
166    struct max7301_platform_data *pdata;
167    int i, ret;
168
169    pdata = dev->platform_data;
170    if (!pdata || !pdata->base) {
171        dev_err(dev, "incorrect or missing platform data\n");
172        return -EINVAL;
173    }
174
175    mutex_init(&ts->lock);
176    dev_set_drvdata(dev, ts);
177
178    /* Power up the chip and disable IRQ output */
179    ts->write(dev, 0x04, 0x01);
180
181    ts->input_pullup_active = pdata->input_pullup_active;
182    ts->chip.label = dev->driver->name;
183
184    ts->chip.direction_input = max7301_direction_input;
185    ts->chip.get = max7301_get;
186    ts->chip.direction_output = max7301_direction_output;
187    ts->chip.set = max7301_set;
188
189    ts->chip.base = pdata->base;
190    ts->chip.ngpio = PIN_NUMBER;
191    ts->chip.can_sleep = 1;
192    ts->chip.dev = dev;
193    ts->chip.owner = THIS_MODULE;
194
195    /*
196     * initialize pullups according to platform data and cache the
197     * register values for later use.
198     */
199    for (i = 1; i < 8; i++) {
200        int j;
201        /*
202         * initialize port_config with "0xAA", which means
203         * input with internal pullup disabled. This is needed
204         * to avoid writing zeros (in the inner for loop),
205         * which is not allowed according to the datasheet.
206         */
207        ts->port_config[i] = 0xAA;
208        for (j = 0; j < 4; j++) {
209            int offset = (i - 1) * 4 + j;
210            ret = max7301_direction_input(&ts->chip, offset);
211            if (ret)
212                goto exit_destroy;
213        }
214    }
215
216    ret = gpiochip_add(&ts->chip);
217    if (ret)
218        goto exit_destroy;
219
220    return ret;
221
222exit_destroy:
223    dev_set_drvdata(dev, NULL);
224    mutex_destroy(&ts->lock);
225    return ret;
226}
227EXPORT_SYMBOL_GPL(__max730x_probe);
228
229int __devexit __max730x_remove(struct device *dev)
230{
231    struct max7301 *ts = dev_get_drvdata(dev);
232    int ret;
233
234    if (ts == NULL)
235        return -ENODEV;
236
237    dev_set_drvdata(dev, NULL);
238
239    /* Power down the chip and disable IRQ output */
240    ts->write(dev, 0x04, 0x00);
241
242    ret = gpiochip_remove(&ts->chip);
243    if (!ret) {
244        mutex_destroy(&ts->lock);
245        kfree(ts);
246    } else
247        dev_err(dev, "Failed to remove GPIO controller: %d\n", ret);
248
249    return ret;
250}
251EXPORT_SYMBOL_GPL(__max730x_remove);
252
253MODULE_AUTHOR("Juergen Beisert, Wolfram Sang");
254MODULE_LICENSE("GPL v2");
255MODULE_DESCRIPTION("MAX730x GPIO-Expanders, generic parts");
256

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