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 | |
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(lock: &ts->lock); |
74 | |
75 | return ret; |
76 | } |
77 | |
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 | |
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(lock: &ts->lock); |
114 | |
115 | return ret; |
116 | } |
117 | |
118 | static int max7301_get(struct gpio_chip *chip, unsigned offset) |
119 | { |
120 | struct max7301 *ts = gpiochip_get_data(gc: 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(lock: &ts->lock); |
142 | |
143 | return level; |
144 | } |
145 | |
146 | static void max7301_set(struct gpio_chip *chip, unsigned offset, int value) |
147 | { |
148 | struct max7301 *ts = gpiochip_get_data(gc: 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(lock: &ts->lock); |
158 | } |
159 | |
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, data: 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(chip: &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(lock: &ts->lock); |
219 | return ret; |
220 | } |
221 | EXPORT_SYMBOL_GPL(__max730x_probe); |
222 | |
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(gc: &ts->chip); |
230 | mutex_destroy(lock: &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 | |