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/driver.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 = gpiochip_get_data(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 = gpiochip_get_data(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 = gpiochip_get_data(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 = gpiochip_get_data(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 __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_get_platdata(dev);
170
171 mutex_init(&ts->lock);
172 dev_set_drvdata(dev, ts);
173
174 /* Power up the chip and disable IRQ output */
175 ts->write(dev, 0x04, 0x01);
176
177 if (pdata) {
178 ts->input_pullup_active = pdata->input_pullup_active;
179 ts->chip.base = pdata->base;
180 } else {
181 ts->chip.base = -1;
182 }
183 ts->chip.label = dev->driver->name;
184
185 ts->chip.direction_input = max7301_direction_input;
186 ts->chip.get = max7301_get;
187 ts->chip.direction_output = max7301_direction_output;
188 ts->chip.set = max7301_set;
189
190 ts->chip.ngpio = PIN_NUMBER;
191 ts->chip.can_sleep = true;
192 ts->chip.parent = dev;
193 ts->chip.owner = THIS_MODULE;
194
195 ret = gpiochip_add_data(&ts->chip, ts);
196 if (ret)
197 goto exit_destroy;
198
199 /*
200 * initialize pullups according to platform data and cache the
201 * register values for later use.
202 */
203 for (i = 1; i < 8; i++) {
204 int j;
205 /*
206 * initialize port_config with "0xAA", which means
207 * input with internal pullup disabled. This is needed
208 * to avoid writing zeros (in the inner for loop),
209 * which is not allowed according to the datasheet.
210 */
211 ts->port_config[i] = 0xAA;
212 for (j = 0; j < 4; j++) {
213 int offset = (i - 1) * 4 + j;
214 ret = max7301_direction_input(&ts->chip, offset);
215 if (ret)
216 goto exit_destroy;
217 }
218 }
219
220 return ret;
221
222exit_destroy:
223 mutex_destroy(&ts->lock);
224 return ret;
225}
226EXPORT_SYMBOL_GPL(__max730x_probe);
227
228int __max730x_remove(struct device *dev)
229{
230 struct max7301 *ts = dev_get_drvdata(dev);
231
232 if (ts == NULL)
233 return -ENODEV;
234
235 /* Power down the chip and disable IRQ output */
236 ts->write(dev, 0x04, 0x00);
237 gpiochip_remove(&ts->chip);
238 mutex_destroy(&ts->lock);
239 return 0;
240}
241EXPORT_SYMBOL_GPL(__max730x_remove);
242
243MODULE_AUTHOR("Juergen Beisert, Wolfram Sang");
244MODULE_LICENSE("GPL v2");
245MODULE_DESCRIPTION("MAX730x GPIO-Expanders, generic parts");
246