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Wolfram Sange9528052010-03-05 13:44:33 -08001/**
2 * drivers/gpio/max7301.c
3 *
4 * Copyright (C) 2006 Juergen Beisert, Pengutronix
5 * Copyright (C) 2008 Guennadi Liakhovetski, Pengutronix
6 * Copyright (C) 2009 Wolfram Sang, Pengutronix
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 *
12 * The Maxim MAX7300/1 device is an I2C/SPI driven GPIO expander. There are
13 * 28 GPIOs. 8 of them can trigger an interrupt. See datasheet for more
14 * details
15 * Note:
16 * - DIN must be stable at the rising edge of clock.
17 * - when writing:
18 * - always clock in 16 clocks at once
19 * - at DIN: D15 first, D0 last
20 * - D0..D7 = databyte, D8..D14 = commandbyte
21 * - D15 = low -> write command
22 * - when reading
23 * - always clock in 16 clocks at once
24 * - at DIN: D15 first, D0 last
25 * - D0..D7 = dummy, D8..D14 = register address
26 * - D15 = high -> read command
27 * - raise CS and assert it again
28 * - always clock in 16 clocks at once
29 * - at DOUT: D15 first, D0 last
30 * - D0..D7 contains the data from the first cycle
31 *
32 * The driver exports a standard gpiochip interface
33 */
34
35#include <linux/module.h>
36#include <linux/init.h>
37#include <linux/platform_device.h>
38#include <linux/mutex.h>
39#include <linux/spi/max7301.h>
40#include <linux/gpio.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090041#include <linux/slab.h>
Wolfram Sange9528052010-03-05 13:44:33 -080042
43/*
44 * Pin configurations, see MAX7301 datasheet page 6
45 */
46#define PIN_CONFIG_MASK 0x03
47#define PIN_CONFIG_IN_PULLUP 0x03
48#define PIN_CONFIG_IN_WO_PULLUP 0x02
49#define PIN_CONFIG_OUT 0x01
50
51#define PIN_NUMBER 28
52
53static int max7301_direction_input(struct gpio_chip *chip, unsigned offset)
54{
55 struct max7301 *ts = container_of(chip, struct max7301, chip);
56 u8 *config;
Marc Kleine-Budde4a22b8a2010-08-10 18:02:23 -070057 u8 offset_bits, pin_config;
Wolfram Sange9528052010-03-05 13:44:33 -080058 int ret;
59
60 /* First 4 pins are unused in the controller */
61 offset += 4;
62 offset_bits = (offset & 3) << 1;
63
64 config = &ts->port_config[offset >> 2];
65
Marc Kleine-Budde4a22b8a2010-08-10 18:02:23 -070066 if (ts->input_pullup_active & BIT(offset))
67 pin_config = PIN_CONFIG_IN_PULLUP;
68 else
69 pin_config = PIN_CONFIG_IN_WO_PULLUP;
70
Wolfram Sange9528052010-03-05 13:44:33 -080071 mutex_lock(&ts->lock);
72
Wolfram Sange9528052010-03-05 13:44:33 -080073 *config = (*config & ~(PIN_CONFIG_MASK << offset_bits))
Marc Kleine-Budde4a22b8a2010-08-10 18:02:23 -070074 | (pin_config << offset_bits);
Wolfram Sange9528052010-03-05 13:44:33 -080075
76 ret = ts->write(ts->dev, 0x08 + (offset >> 2), *config);
77
78 mutex_unlock(&ts->lock);
79
80 return ret;
81}
82
83static int __max7301_set(struct max7301 *ts, unsigned offset, int value)
84{
85 if (value) {
86 ts->out_level |= 1 << offset;
87 return ts->write(ts->dev, 0x20 + offset, 0x01);
88 } else {
89 ts->out_level &= ~(1 << offset);
90 return ts->write(ts->dev, 0x20 + offset, 0x00);
91 }
92}
93
94static int max7301_direction_output(struct gpio_chip *chip, unsigned offset,
95 int value)
96{
97 struct max7301 *ts = container_of(chip, struct max7301, chip);
98 u8 *config;
99 u8 offset_bits;
100 int ret;
101
102 /* First 4 pins are unused in the controller */
103 offset += 4;
104 offset_bits = (offset & 3) << 1;
105
106 config = &ts->port_config[offset >> 2];
107
108 mutex_lock(&ts->lock);
109
110 *config = (*config & ~(PIN_CONFIG_MASK << offset_bits))
111 | (PIN_CONFIG_OUT << offset_bits);
112
113 ret = __max7301_set(ts, offset, value);
114
115 if (!ret)
116 ret = ts->write(ts->dev, 0x08 + (offset >> 2), *config);
117
118 mutex_unlock(&ts->lock);
119
120 return ret;
121}
122
123static int max7301_get(struct gpio_chip *chip, unsigned offset)
124{
125 struct max7301 *ts = container_of(chip, struct max7301, chip);
126 int config, level = -EINVAL;
127
128 /* First 4 pins are unused in the controller */
129 offset += 4;
130
131 mutex_lock(&ts->lock);
132
133 config = (ts->port_config[offset >> 2] >> ((offset & 3) << 1))
134 & PIN_CONFIG_MASK;
135
136 switch (config) {
137 case PIN_CONFIG_OUT:
138 /* Output: return cached level */
139 level = !!(ts->out_level & (1 << offset));
140 break;
141 case PIN_CONFIG_IN_WO_PULLUP:
142 case PIN_CONFIG_IN_PULLUP:
143 /* Input: read out */
144 level = ts->read(ts->dev, 0x20 + offset) & 0x01;
145 }
146 mutex_unlock(&ts->lock);
147
148 return level;
149}
150
151static void max7301_set(struct gpio_chip *chip, unsigned offset, int value)
152{
153 struct max7301 *ts = container_of(chip, struct max7301, chip);
154
155 /* First 4 pins are unused in the controller */
156 offset += 4;
157
158 mutex_lock(&ts->lock);
159
160 __max7301_set(ts, offset, value);
161
162 mutex_unlock(&ts->lock);
163}
164
165int __devinit __max730x_probe(struct max7301 *ts)
166{
167 struct device *dev = ts->dev;
168 struct max7301_platform_data *pdata;
169 int i, ret;
170
171 pdata = dev->platform_data;
172 if (!pdata || !pdata->base) {
173 dev_err(dev, "incorrect or missing platform data\n");
174 return -EINVAL;
175 }
176
177 mutex_init(&ts->lock);
178 dev_set_drvdata(dev, ts);
179
180 /* Power up the chip and disable IRQ output */
181 ts->write(dev, 0x04, 0x01);
182
Marc Kleine-Budde4a22b8a2010-08-10 18:02:23 -0700183 ts->input_pullup_active = pdata->input_pullup_active;
Wolfram Sange9528052010-03-05 13:44:33 -0800184 ts->chip.label = dev->driver->name;
185
186 ts->chip.direction_input = max7301_direction_input;
187 ts->chip.get = max7301_get;
188 ts->chip.direction_output = max7301_direction_output;
189 ts->chip.set = max7301_set;
190
191 ts->chip.base = pdata->base;
192 ts->chip.ngpio = PIN_NUMBER;
193 ts->chip.can_sleep = 1;
194 ts->chip.dev = dev;
195 ts->chip.owner = THIS_MODULE;
196
197 /*
Marc Kleine-Budde4a22b8a2010-08-10 18:02:23 -0700198 * initialize pullups according to platform data and cache the
Wolfram Sange9528052010-03-05 13:44:33 -0800199 * register values for later use.
200 */
201 for (i = 1; i < 8; i++) {
202 int j;
Marc Kleine-Budde4a22b8a2010-08-10 18:02:23 -0700203 /*
204 * initialize port_config with "0xAA", which means
205 * input with internal pullup disabled. This is needed
206 * to avoid writing zeros (in the inner for loop),
207 * which is not allowed according to the datasheet.
208 */
Wolfram Sange9528052010-03-05 13:44:33 -0800209 ts->port_config[i] = 0xAA;
210 for (j = 0; j < 4; j++) {
211 int offset = (i - 1) * 4 + j;
212 ret = max7301_direction_input(&ts->chip, offset);
213 if (ret)
214 goto exit_destroy;
215 }
216 }
217
218 ret = gpiochip_add(&ts->chip);
219 if (ret)
220 goto exit_destroy;
221
222 return ret;
223
224exit_destroy:
225 dev_set_drvdata(dev, NULL);
226 mutex_destroy(&ts->lock);
227 return ret;
228}
229EXPORT_SYMBOL_GPL(__max730x_probe);
230
231int __devexit __max730x_remove(struct device *dev)
232{
233 struct max7301 *ts = dev_get_drvdata(dev);
234 int ret;
235
236 if (ts == NULL)
237 return -ENODEV;
238
239 dev_set_drvdata(dev, NULL);
240
241 /* Power down the chip and disable IRQ output */
242 ts->write(dev, 0x04, 0x00);
243
244 ret = gpiochip_remove(&ts->chip);
245 if (!ret) {
246 mutex_destroy(&ts->lock);
247 kfree(ts);
248 } else
249 dev_err(dev, "Failed to remove GPIO controller: %d\n", ret);
250
251 return ret;
252}
253EXPORT_SYMBOL_GPL(__max730x_remove);
Richard Röjfors06ca02b2010-03-23 13:35:20 -0700254
255MODULE_AUTHOR("Juergen Beisert, Wolfram Sang");
256MODULE_LICENSE("GPL v2");
257MODULE_DESCRIPTION("MAX730x GPIO-Expanders, generic parts");