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 
max7301_direction_input(struct gpio_chip * chip,unsigned offset)48 static 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 
__max7301_set(struct max7301 * ts,unsigned offset,int value)78 static 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 
max7301_direction_output(struct gpio_chip * chip,unsigned offset,int value)89 static 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 
max7301_get(struct gpio_chip * chip,unsigned offset)118 static 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 
max7301_set(struct gpio_chip * chip,unsigned offset,int value)146 static 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 
__max730x_probe(struct max7301 * ts)160 int __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 
217 exit_destroy:
218 	mutex_destroy(&ts->lock);
219 	return ret;
220 }
221 EXPORT_SYMBOL_GPL(__max730x_probe);
222 
__max730x_remove(struct device * dev)223 void __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 }
232 EXPORT_SYMBOL_GPL(__max730x_remove);
233 
234 MODULE_AUTHOR("Juergen Beisert, Wolfram Sang");
235 MODULE_LICENSE("GPL v2");
236 MODULE_DESCRIPTION("MAX730x GPIO-Expanders, generic parts");
237