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 __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.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	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