1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copyright (C) 2006 Juergen Beisert, Pengutronix
4 * Copyright (C) 2008 Guennadi Liakhovetski, Pengutronix
5 * Copyright (C) 2009 Wolfram Sang, Pengutronix
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
11 * - DIN must be stable at the rising edge of clock.
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
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
27 * The driver exports a standard gpiochip interface
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>
39 * Pin configurations, see MAX7301 datasheet page 6
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
48 static int max7301_direction_input(struct gpio_chip
*chip
, unsigned offset
)
50 struct max7301
*ts
= container_of(chip
, struct max7301
, chip
);
52 u8 offset_bits
, pin_config
;
55 /* First 4 pins are unused in the controller */
57 offset_bits
= (offset
& 3) << 1;
59 config
= &ts
->port_config
[offset
>> 2];
61 if (ts
->input_pullup_active
& BIT(offset
))
62 pin_config
= PIN_CONFIG_IN_PULLUP
;
64 pin_config
= PIN_CONFIG_IN_WO_PULLUP
;
66 mutex_lock(&ts
->lock
);
68 *config
= (*config
& ~(PIN_CONFIG_MASK
<< offset_bits
))
69 | (pin_config
<< offset_bits
);
71 ret
= ts
->write(ts
->dev
, 0x08 + (offset
>> 2), *config
);
73 mutex_unlock(&ts
->lock
);
78 static int __max7301_set(struct max7301
*ts
, unsigned offset
, int value
)
81 ts
->out_level
|= 1 << offset
;
82 return ts
->write(ts
->dev
, 0x20 + offset
, 0x01);
84 ts
->out_level
&= ~(1 << offset
);
85 return ts
->write(ts
->dev
, 0x20 + offset
, 0x00);
89 static int max7301_direction_output(struct gpio_chip
*chip
, unsigned offset
,
92 struct max7301
*ts
= container_of(chip
, struct max7301
, chip
);
97 /* First 4 pins are unused in the controller */
99 offset_bits
= (offset
& 3) << 1;
101 config
= &ts
->port_config
[offset
>> 2];
103 mutex_lock(&ts
->lock
);
105 *config
= (*config
& ~(PIN_CONFIG_MASK
<< offset_bits
))
106 | (PIN_CONFIG_OUT
<< offset_bits
);
108 ret
= __max7301_set(ts
, offset
, value
);
111 ret
= ts
->write(ts
->dev
, 0x08 + (offset
>> 2), *config
);
113 mutex_unlock(&ts
->lock
);
118 static int max7301_get(struct gpio_chip
*chip
, unsigned offset
)
120 struct max7301
*ts
= gpiochip_get_data(chip
);
121 int config
, level
= -EINVAL
;
123 /* First 4 pins are unused in the controller */
126 mutex_lock(&ts
->lock
);
128 config
= (ts
->port_config
[offset
>> 2] >> ((offset
& 3) << 1))
133 /* Output: return cached level */
134 level
= !!(ts
->out_level
& (1 << offset
));
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;
141 mutex_unlock(&ts
->lock
);
146 static void max7301_set(struct gpio_chip
*chip
, unsigned offset
, int value
)
148 struct max7301
*ts
= gpiochip_get_data(chip
);
150 /* First 4 pins are unused in the controller */
153 mutex_lock(&ts
->lock
);
155 __max7301_set(ts
, offset
, value
);
157 mutex_unlock(&ts
->lock
);
160 int __max730x_probe(struct max7301
*ts
)
162 struct device
*dev
= ts
->dev
;
163 struct max7301_platform_data
*pdata
;
166 pdata
= dev_get_platdata(dev
);
168 mutex_init(&ts
->lock
);
169 dev_set_drvdata(dev
, ts
);
171 /* Power up the chip and disable IRQ output */
172 ts
->write(dev
, 0x04, 0x01);
175 ts
->input_pullup_active
= pdata
->input_pullup_active
;
176 ts
->chip
.base
= pdata
->base
;
180 ts
->chip
.label
= dev
->driver
->name
;
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
;
187 ts
->chip
.ngpio
= PIN_NUMBER
;
188 ts
->chip
.can_sleep
= true;
189 ts
->chip
.parent
= dev
;
190 ts
->chip
.owner
= THIS_MODULE
;
193 * initialize pullups according to platform data and cache the
194 * register values for later use.
196 for (i
= 1; i
< 8; i
++) {
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.
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
);
213 ret
= gpiochip_add_data(&ts
->chip
, ts
);
218 mutex_destroy(&ts
->lock
);
221 EXPORT_SYMBOL_GPL(__max730x_probe
);
223 int __max730x_remove(struct device
*dev
)
225 struct max7301
*ts
= dev_get_drvdata(dev
);
230 /* Power down the chip and disable IRQ output */
231 ts
->write(dev
, 0x04, 0x00);
232 gpiochip_remove(&ts
->chip
);
233 mutex_destroy(&ts
->lock
);
236 EXPORT_SYMBOL_GPL(__max730x_remove
);
238 MODULE_AUTHOR("Juergen Beisert, Wolfram Sang");
239 MODULE_LICENSE("GPL v2");
240 MODULE_DESCRIPTION("MAX730x GPIO-Expanders, generic parts");