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1 | /** |
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> | |
41 | ||
42 | /* | |
43 | * Pin configurations, see MAX7301 datasheet page 6 | |
44 | */ | |
45 | #define PIN_CONFIG_MASK 0x03 | |
46 | #define PIN_CONFIG_IN_PULLUP 0x03 | |
47 | #define PIN_CONFIG_IN_WO_PULLUP 0x02 | |
48 | #define PIN_CONFIG_OUT 0x01 | |
49 | ||
50 | #define PIN_NUMBER 28 | |
51 | ||
52 | static int max7301_direction_input(struct gpio_chip *chip, unsigned offset) | |
53 | { | |
54 | struct max7301 *ts = container_of(chip, struct max7301, chip); | |
55 | u8 *config; | |
56 | u8 offset_bits; | |
57 | int ret; | |
58 | ||
59 | /* First 4 pins are unused in the controller */ | |
60 | offset += 4; | |
61 | offset_bits = (offset & 3) << 1; | |
62 | ||
63 | config = &ts->port_config[offset >> 2]; | |
64 | ||
65 | mutex_lock(&ts->lock); | |
66 | ||
67 | /* Standard GPIO API doesn't support pull-ups, has to be extended. | |
68 | * Hard-coding no pollup for now. */ | |
69 | *config = (*config & ~(PIN_CONFIG_MASK << offset_bits)) | |
70 | | (PIN_CONFIG_IN_WO_PULLUP << offset_bits); | |
71 | ||
72 | ret = ts->write(ts->dev, 0x08 + (offset >> 2), *config); | |
73 | ||
74 | mutex_unlock(&ts->lock); | |
75 | ||
76 | return ret; | |
77 | } | |
78 | ||
79 | static int __max7301_set(struct max7301 *ts, unsigned offset, int value) | |
80 | { | |
81 | if (value) { | |
82 | ts->out_level |= 1 << offset; | |
83 | return ts->write(ts->dev, 0x20 + offset, 0x01); | |
84 | } else { | |
85 | ts->out_level &= ~(1 << offset); | |
86 | return ts->write(ts->dev, 0x20 + offset, 0x00); | |
87 | } | |
88 | } | |
89 | ||
90 | static int max7301_direction_output(struct gpio_chip *chip, unsigned offset, | |
91 | int value) | |
92 | { | |
93 | struct max7301 *ts = container_of(chip, struct max7301, chip); | |
94 | u8 *config; | |
95 | u8 offset_bits; | |
96 | int ret; | |
97 | ||
98 | /* First 4 pins are unused in the controller */ | |
99 | offset += 4; | |
100 | offset_bits = (offset & 3) << 1; | |
101 | ||
102 | config = &ts->port_config[offset >> 2]; | |
103 | ||
104 | mutex_lock(&ts->lock); | |
105 | ||
106 | *config = (*config & ~(PIN_CONFIG_MASK << offset_bits)) | |
107 | | (PIN_CONFIG_OUT << offset_bits); | |
108 | ||
109 | ret = __max7301_set(ts, offset, value); | |
110 | ||
111 | if (!ret) | |
112 | ret = ts->write(ts->dev, 0x08 + (offset >> 2), *config); | |
113 | ||
114 | mutex_unlock(&ts->lock); | |
115 | ||
116 | return ret; | |
117 | } | |
118 | ||
119 | static int max7301_get(struct gpio_chip *chip, unsigned offset) | |
120 | { | |
121 | struct max7301 *ts = container_of(chip, struct max7301, chip); | |
122 | int config, level = -EINVAL; | |
123 | ||
124 | /* First 4 pins are unused in the controller */ | |
125 | offset += 4; | |
126 | ||
127 | mutex_lock(&ts->lock); | |
128 | ||
129 | config = (ts->port_config[offset >> 2] >> ((offset & 3) << 1)) | |
130 | & PIN_CONFIG_MASK; | |
131 | ||
132 | switch (config) { | |
133 | case PIN_CONFIG_OUT: | |
134 | /* Output: return cached level */ | |
135 | level = !!(ts->out_level & (1 << offset)); | |
136 | break; | |
137 | case PIN_CONFIG_IN_WO_PULLUP: | |
138 | case PIN_CONFIG_IN_PULLUP: | |
139 | /* Input: read out */ | |
140 | level = ts->read(ts->dev, 0x20 + offset) & 0x01; | |
141 | } | |
142 | mutex_unlock(&ts->lock); | |
143 | ||
144 | return level; | |
145 | } | |
146 | ||
147 | static void max7301_set(struct gpio_chip *chip, unsigned offset, int value) | |
148 | { | |
149 | struct max7301 *ts = container_of(chip, struct max7301, chip); | |
150 | ||
151 | /* First 4 pins are unused in the controller */ | |
152 | offset += 4; | |
153 | ||
154 | mutex_lock(&ts->lock); | |
155 | ||
156 | __max7301_set(ts, offset, value); | |
157 | ||
158 | mutex_unlock(&ts->lock); | |
159 | } | |
160 | ||
161 | int __devinit __max730x_probe(struct max7301 *ts) | |
162 | { | |
163 | struct device *dev = ts->dev; | |
164 | struct max7301_platform_data *pdata; | |
165 | int i, ret; | |
166 | ||
167 | pdata = dev->platform_data; | |
168 | if (!pdata || !pdata->base) { | |
169 | dev_err(dev, "incorrect or missing platform data\n"); | |
170 | return -EINVAL; | |
171 | } | |
172 | ||
173 | mutex_init(&ts->lock); | |
174 | dev_set_drvdata(dev, ts); | |
175 | ||
176 | /* Power up the chip and disable IRQ output */ | |
177 | ts->write(dev, 0x04, 0x01); | |
178 | ||
179 | ts->chip.label = dev->driver->name; | |
180 | ||
181 | ts->chip.direction_input = max7301_direction_input; | |
182 | ts->chip.get = max7301_get; | |
183 | ts->chip.direction_output = max7301_direction_output; | |
184 | ts->chip.set = max7301_set; | |
185 | ||
186 | ts->chip.base = pdata->base; | |
187 | ts->chip.ngpio = PIN_NUMBER; | |
188 | ts->chip.can_sleep = 1; | |
189 | ts->chip.dev = dev; | |
190 | ts->chip.owner = THIS_MODULE; | |
191 | ||
192 | /* | |
193 | * tristate all pins in hardware and cache the | |
194 | * register values for later use. | |
195 | */ | |
196 | for (i = 1; i < 8; i++) { | |
197 | int j; | |
198 | /* 0xAA means input with internal pullup disabled */ | |
199 | ts->write(dev, 0x08 + i, 0xAA); | |
200 | ts->port_config[i] = 0xAA; | |
201 | for (j = 0; j < 4; j++) { | |
202 | int offset = (i - 1) * 4 + j; | |
203 | ret = max7301_direction_input(&ts->chip, offset); | |
204 | if (ret) | |
205 | goto exit_destroy; | |
206 | } | |
207 | } | |
208 | ||
209 | ret = gpiochip_add(&ts->chip); | |
210 | if (ret) | |
211 | goto exit_destroy; | |
212 | ||
213 | return ret; | |
214 | ||
215 | exit_destroy: | |
216 | dev_set_drvdata(dev, NULL); | |
217 | mutex_destroy(&ts->lock); | |
218 | return ret; | |
219 | } | |
220 | EXPORT_SYMBOL_GPL(__max730x_probe); | |
221 | ||
222 | int __devexit __max730x_remove(struct device *dev) | |
223 | { | |
224 | struct max7301 *ts = dev_get_drvdata(dev); | |
225 | int ret; | |
226 | ||
227 | if (ts == NULL) | |
228 | return -ENODEV; | |
229 | ||
230 | dev_set_drvdata(dev, NULL); | |
231 | ||
232 | /* Power down the chip and disable IRQ output */ | |
233 | ts->write(dev, 0x04, 0x00); | |
234 | ||
235 | ret = gpiochip_remove(&ts->chip); | |
236 | if (!ret) { | |
237 | mutex_destroy(&ts->lock); | |
238 | kfree(ts); | |
239 | } else | |
240 | dev_err(dev, "Failed to remove GPIO controller: %d\n", ret); | |
241 | ||
242 | return ret; | |
243 | } | |
244 | EXPORT_SYMBOL_GPL(__max730x_remove); |