gpio-max730x.c

  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 int max7301_set(struct gpio_chip *chip, unsigned int offset, int value)
147{
148	struct max7301 *ts = gpiochip_get_data(chip);
149	int ret;
150
151	/* First 4 pins are unused in the controller */
152	offset += 4;
153
154	mutex_lock(&ts->lock);
155
156	ret = __max7301_set(ts, offset, value);
157
158	mutex_unlock(&ts->lock);
159
160	return ret;
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	ret = devm_mutex_init(ts->dev, &ts->lock);
172	if (ret)
173		return ret;
174
175	dev_set_drvdata(dev, ts);
176
177	/* Power up the chip and disable IRQ output */
178	ts->write(dev, 0x04, 0x01);
179
180	if (pdata) {
181		ts->input_pullup_active = pdata->input_pullup_active;
182		ts->chip.base = pdata->base;
183	} else {
184		ts->chip.base = -1;
185	}
186	ts->chip.label = dev->driver->name;
187
188	ts->chip.direction_input = max7301_direction_input;
189	ts->chip.get = max7301_get;
190	ts->chip.direction_output = max7301_direction_output;
191	ts->chip.set = max7301_set;
192
193	ts->chip.ngpio = PIN_NUMBER;
194	ts->chip.can_sleep = true;
195	ts->chip.parent = dev;
196	ts->chip.owner = THIS_MODULE;
197
198	/*
199	 * initialize pullups according to platform data and cache the
200	 * register values for later use.
201	 */
202	for (i = 1; i < 8; i++) {
203		int j;
204		/*
205		 * initialize port_config with "0xAA", which means
206		 * input with internal pullup disabled. This is needed
207		 * to avoid writing zeros (in the inner for loop),
208		 * which is not allowed according to the datasheet.
209		 */
210		ts->port_config[i] = 0xAA;
211		for (j = 0; j < 4; j++) {
212			int offset = (i - 1) * 4 + j;
213			ret = max7301_direction_input(&ts->chip, offset);
214			if (ret)
215				return ret;
216		}
217	}
218
219	return devm_gpiochip_add_data(ts->dev, &ts->chip, ts);
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}
230EXPORT_SYMBOL_GPL(__max730x_remove);
231
232MODULE_AUTHOR("Juergen Beisert, Wolfram Sang");
233MODULE_LICENSE("GPL v2");
234MODULE_DESCRIPTION("MAX730x GPIO-Expanders, generic parts");