2 * Copyright (C) 2006 Juergen Beisert, Pengutronix
3 * Copyright (C) 2008 Guennadi Liakhovetski, Pengutronix
4 * Copyright (C) 2009 Wolfram Sang, Pengutronix
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.
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
14 * - DIN must be stable at the rising edge of clock.
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
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
30 * The driver exports a standard gpiochip interface
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>
42 * Pin configurations, see MAX7301 datasheet page 6
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
51 static int max7301_direction_input(struct gpio_chip *chip, unsigned offset)
53 struct max7301 *ts = container_of(chip, struct max7301, chip);
55 u8 offset_bits, pin_config;
58 /* First 4 pins are unused in the controller */
60 offset_bits = (offset & 3) << 1;
62 config = &ts->port_config[offset >> 2];
64 if (ts->input_pullup_active & BIT(offset))
65 pin_config = PIN_CONFIG_IN_PULLUP;
67 pin_config = PIN_CONFIG_IN_WO_PULLUP;
69 mutex_lock(&ts->lock);
71 *config = (*config & ~(PIN_CONFIG_MASK << offset_bits))
72 | (pin_config << offset_bits);
74 ret = ts->write(ts->dev, 0x08 + (offset >> 2), *config);
76 mutex_unlock(&ts->lock);
81 static int __max7301_set(struct max7301 *ts, unsigned offset, int value)
84 ts->out_level |= 1 << offset;
85 return ts->write(ts->dev, 0x20 + offset, 0x01);
87 ts->out_level &= ~(1 << offset);
88 return ts->write(ts->dev, 0x20 + offset, 0x00);
92 static int max7301_direction_output(struct gpio_chip *chip, unsigned offset,
95 struct max7301 *ts = container_of(chip, struct max7301, chip);
100 /* First 4 pins are unused in the controller */
102 offset_bits = (offset & 3) << 1;
104 config = &ts->port_config[offset >> 2];
106 mutex_lock(&ts->lock);
108 *config = (*config & ~(PIN_CONFIG_MASK << offset_bits))
109 | (PIN_CONFIG_OUT << offset_bits);
111 ret = __max7301_set(ts, offset, value);
114 ret = ts->write(ts->dev, 0x08 + (offset >> 2), *config);
116 mutex_unlock(&ts->lock);
121 static int max7301_get(struct gpio_chip *chip, unsigned offset)
123 struct max7301 *ts = container_of(chip, struct max7301, chip);
124 int config, level = -EINVAL;
126 /* First 4 pins are unused in the controller */
129 mutex_lock(&ts->lock);
131 config = (ts->port_config[offset >> 2] >> ((offset & 3) << 1))
136 /* Output: return cached level */
137 level = !!(ts->out_level & (1 << offset));
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;
144 mutex_unlock(&ts->lock);
149 static void max7301_set(struct gpio_chip *chip, unsigned offset, int value)
151 struct max7301 *ts = container_of(chip, struct max7301, chip);
153 /* First 4 pins are unused in the controller */
156 mutex_lock(&ts->lock);
158 __max7301_set(ts, offset, value);
160 mutex_unlock(&ts->lock);
163 int __devinit __max730x_probe(struct max7301 *ts)
165 struct device *dev = ts->dev;
166 struct max7301_platform_data *pdata;
169 pdata = dev->platform_data;
171 mutex_init(&ts->lock);
172 dev_set_drvdata(dev, ts);
174 /* Power up the chip and disable IRQ output */
175 ts->write(dev, 0x04, 0x01);
178 ts->input_pullup_active = pdata->input_pullup_active;
179 ts->chip.base = pdata->base;
183 ts->chip.label = dev->driver->name;
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;
190 ts->chip.ngpio = PIN_NUMBER;
191 ts->chip.can_sleep = 1;
193 ts->chip.owner = THIS_MODULE;
196 * initialize pullups according to platform data and cache the
197 * register values for later use.
199 for (i = 1; i < 8; i++) {
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.
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);
216 ret = gpiochip_add(&ts->chip);
223 dev_set_drvdata(dev, NULL);
224 mutex_destroy(&ts->lock);
227 EXPORT_SYMBOL_GPL(__max730x_probe);
229 int __devexit __max730x_remove(struct device *dev)
231 struct max7301 *ts = dev_get_drvdata(dev);
237 dev_set_drvdata(dev, NULL);
239 /* Power down the chip and disable IRQ output */
240 ts->write(dev, 0x04, 0x00);
242 ret = gpiochip_remove(&ts->chip);
244 mutex_destroy(&ts->lock);
247 dev_err(dev, "Failed to remove GPIO controller: %d\n", ret);
251 EXPORT_SYMBOL_GPL(__max730x_remove);
253 MODULE_AUTHOR("Juergen Beisert, Wolfram Sang");
254 MODULE_LICENSE("GPL v2");
255 MODULE_DESCRIPTION("MAX730x GPIO-Expanders, generic parts");