1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2006 Juergen Beisert, Pengutronix
4 * Copyright (C) 2008 Guennadi Liakhovetski, Pengutronix
5 * Copyright (C) 2009 Wolfram Sang, Pengutronix
6 *
7 * The Maxim MAX7300/1 device is an I2C/SPI driven GPIO expander. There are
8 * 28 GPIOs. 8 of them can trigger an interrupt. See datasheet for more
9 * details
10 * Note:
11 * - DIN must be stable at the rising edge of clock.
12 * - when writing:
13 *   - always clock in 16 clocks at once
14 *   - at DIN: D15 first, D0 last
15 *   - D0..D7 = databyte, D8..D14 = commandbyte
16 *   - D15 = low -> write command
17 * - when reading
18 *   - always clock in 16 clocks at once
19 *   - at DIN: D15 first, D0 last
20 *   - D0..D7 = dummy, D8..D14 = register address
21 *   - D15 = high -> read command
22 *   - raise CS and assert it again
23 *   - always clock in 16 clocks at once
24 *   - at DOUT: D15 first, D0 last
25 *   - D0..D7 contains the data from the first cycle
26 *
27 * The driver exports a standard gpiochip interface
28 */
29
30#include <linux/module.h>
31#include <linux/init.h>
32#include <linux/platform_device.h>
33#include <linux/mutex.h>
34#include <linux/spi/max7301.h>
35#include <linux/gpio/driver.h>
36#include <linux/slab.h>
37
38/*
39 * Pin configurations, see MAX7301 datasheet page 6
40 */
41#define PIN_CONFIG_MASK 0x03
42#define PIN_CONFIG_IN_PULLUP 0x03
43#define PIN_CONFIG_IN_WO_PULLUP 0x02
44#define PIN_CONFIG_OUT 0x01
45
46#define PIN_NUMBER 28
47
48static int max7301_direction_input(struct gpio_chip *chip, unsigned offset)
49{
50	struct max7301 *ts = container_of(chip, struct max7301, chip);
51	u8 *config;
52	u8 offset_bits, pin_config;
53	int ret;
54
55	/* First 4 pins are unused in the controller */
56	offset += 4;
57	offset_bits = (offset & 3) << 1;
58
59	config = &ts->port_config[offset >> 2];
60
61	if (ts->input_pullup_active & BIT(offset))
62		pin_config = PIN_CONFIG_IN_PULLUP;
63	else
64		pin_config = PIN_CONFIG_IN_WO_PULLUP;
65
66	mutex_lock(&ts->lock);
67
68	*config = (*config & ~(PIN_CONFIG_MASK << offset_bits))
69			   | (pin_config << offset_bits);
70
71	ret = ts->write(ts->dev, 0x08 + (offset >> 2), *config);
72
73	mutex_unlock(&ts->lock);
74
75	return ret;
76}
77
78static int __max7301_set(struct max7301 *ts, unsigned offset, int value)
79{
80	if (value) {
81		ts->out_level |= 1 << offset;
82		return ts->write(ts->dev, 0x20 + offset, 0x01);
83	} else {
84		ts->out_level &= ~(1 << offset);
85		return ts->write(ts->dev, 0x20 + offset, 0x00);
86	}
87}
88
89static int max7301_direction_output(struct gpio_chip *chip, unsigned offset,
90				    int value)
91{
92	struct max7301 *ts = container_of(chip, struct max7301, chip);
93	u8 *config;
94	u8 offset_bits;
95	int ret;
96
97	/* First 4 pins are unused in the controller */
98	offset += 4;
99	offset_bits = (offset & 3) << 1;
100
101	config = &ts->port_config[offset >> 2];
102
103	mutex_lock(&ts->lock);
104
105	*config = (*config & ~(PIN_CONFIG_MASK << offset_bits))
106			   | (PIN_CONFIG_OUT << offset_bits);
107
108	ret = __max7301_set(ts, offset, value);
109
110	if (!ret)
111		ret = ts->write(ts->dev, 0x08 + (offset >> 2), *config);
112
113	mutex_unlock(&ts->lock);
114
115	return ret;
116}
117
118static int max7301_get(struct gpio_chip *chip, unsigned offset)
119{
120	struct max7301 *ts = gpiochip_get_data(chip);
121	int config, level = -EINVAL;
122
123	/* First 4 pins are unused in the controller */
124	offset += 4;
125
126	mutex_lock(&ts->lock);
127
128	config = (ts->port_config[offset >> 2] >> ((offset & 3) << 1))
129			& PIN_CONFIG_MASK;
130
131	switch (config) {
132	case PIN_CONFIG_OUT:
133		/* Output: return cached level */
134		level =  !!(ts->out_level & (1 << offset));
135		break;
136	case PIN_CONFIG_IN_WO_PULLUP:
137	case PIN_CONFIG_IN_PULLUP:
138		/* Input: read out */
139		level = ts->read(ts->dev, 0x20 + offset) & 0x01;
140	}
141	mutex_unlock(&ts->lock);
142
143	return level;
144}
145
146static void max7301_set(struct gpio_chip *chip, unsigned offset, int value)
147{
148	struct max7301 *ts = gpiochip_get_data(chip);
149
150	/* First 4 pins are unused in the controller */
151	offset += 4;
152
153	mutex_lock(&ts->lock);
154
155	__max7301_set(ts, offset, value);
156
157	mutex_unlock(&ts->lock);
158}
159
160int __max730x_probe(struct max7301 *ts)
161{
162	struct device *dev = ts->dev;
163	struct max7301_platform_data *pdata;
164	int i, ret;
165
166	pdata = dev_get_platdata(dev);
167
168	mutex_init(&ts->lock);
169	dev_set_drvdata(dev, ts);
170
171	/* Power up the chip and disable IRQ output */
172	ts->write(dev, 0x04, 0x01);
173
174	if (pdata) {
175		ts->input_pullup_active = pdata->input_pullup_active;
176		ts->chip.base = pdata->base;
177	} else {
178		ts->chip.base = -1;
179	}
180	ts->chip.label = dev->driver->name;
181
182	ts->chip.direction_input = max7301_direction_input;
183	ts->chip.get = max7301_get;
184	ts->chip.direction_output = max7301_direction_output;
185	ts->chip.set = max7301_set;
186
187	ts->chip.ngpio = PIN_NUMBER;
188	ts->chip.can_sleep = true;
189	ts->chip.parent = dev;
190	ts->chip.owner = THIS_MODULE;
191
192	/*
193	 * initialize pullups according to platform data and cache the
194	 * register values for later use.
195	 */
196	for (i = 1; i < 8; i++) {
197		int j;
198		/*
199		 * initialize port_config with "0xAA", which means
200		 * input with internal pullup disabled. This is needed
201		 * to avoid writing zeros (in the inner for loop),
202		 * which is not allowed according to the datasheet.
203		 */
204		ts->port_config[i] = 0xAA;
205		for (j = 0; j < 4; j++) {
206			int offset = (i - 1) * 4 + j;
207			ret = max7301_direction_input(&ts->chip, offset);
208			if (ret)
209				goto exit_destroy;
210		}
211	}
212
213	ret = gpiochip_add_data(&ts->chip, ts);
214	if (!ret)
215		return ret;
216
217exit_destroy:
218	mutex_destroy(&ts->lock);
219	return ret;
220}
221EXPORT_SYMBOL_GPL(__max730x_probe);
222
223void __max730x_remove(struct device *dev)
224{
225	struct max7301 *ts = dev_get_drvdata(dev);
226
227	/* Power down the chip and disable IRQ output */
228	ts->write(dev, 0x04, 0x00);
229	gpiochip_remove(&ts->chip);
230	mutex_destroy(&ts->lock);
231}
232EXPORT_SYMBOL_GPL(__max730x_remove);
233
234MODULE_AUTHOR("Juergen Beisert, Wolfram Sang");
235MODULE_LICENSE("GPL v2");
236MODULE_DESCRIPTION("MAX730x GPIO-Expanders, generic parts");
237