1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Driver for PCA9570 I2C GPO expander
4 *
5 * Copyright (C) 2020 Sungbo Eo <mans0n@gorani.run>
6 *
7 * Based on gpio-tpic2810.c
8 * Copyright (C) 2015 Texas Instruments Incorporated - http://www.ti.com/
9 * Andrew F. Davis <afd@ti.com>
10 */
11
12 #include <linux/gpio/driver.h>
13 #include <linux/i2c.h>
14 #include <linux/module.h>
15 #include <linux/mutex.h>
16 #include <linux/property.h>
17
18 /**
19 * struct pca9570 - GPIO driver data
20 * @chip: GPIO controller chip
21 * @lock: Protects write sequences
22 * @out: Buffer for device register
23 */
24 struct pca9570 {
25 struct gpio_chip chip;
26 struct mutex lock;
27 u8 out;
28 };
29
pca9570_read(struct pca9570 * gpio,u8 * value)30 static int pca9570_read(struct pca9570 *gpio, u8 *value)
31 {
32 struct i2c_client *client = to_i2c_client(gpio->chip.parent);
33 int ret;
34
35 ret = i2c_smbus_read_byte(client);
36 if (ret < 0)
37 return ret;
38
39 *value = ret;
40 return 0;
41 }
42
pca9570_write(struct pca9570 * gpio,u8 value)43 static int pca9570_write(struct pca9570 *gpio, u8 value)
44 {
45 struct i2c_client *client = to_i2c_client(gpio->chip.parent);
46
47 return i2c_smbus_write_byte(client, value);
48 }
49
pca9570_get_direction(struct gpio_chip * chip,unsigned offset)50 static int pca9570_get_direction(struct gpio_chip *chip,
51 unsigned offset)
52 {
53 /* This device always output */
54 return GPIO_LINE_DIRECTION_OUT;
55 }
56
pca9570_get(struct gpio_chip * chip,unsigned offset)57 static int pca9570_get(struct gpio_chip *chip, unsigned offset)
58 {
59 struct pca9570 *gpio = gpiochip_get_data(chip);
60 u8 buffer;
61 int ret;
62
63 ret = pca9570_read(gpio, &buffer);
64 if (ret)
65 return ret;
66
67 return !!(buffer & BIT(offset));
68 }
69
pca9570_set(struct gpio_chip * chip,unsigned offset,int value)70 static void pca9570_set(struct gpio_chip *chip, unsigned offset, int value)
71 {
72 struct pca9570 *gpio = gpiochip_get_data(chip);
73 u8 buffer;
74 int ret;
75
76 mutex_lock(&gpio->lock);
77
78 buffer = gpio->out;
79 if (value)
80 buffer |= BIT(offset);
81 else
82 buffer &= ~BIT(offset);
83
84 ret = pca9570_write(gpio, buffer);
85 if (ret)
86 goto out;
87
88 gpio->out = buffer;
89
90 out:
91 mutex_unlock(&gpio->lock);
92 }
93
pca9570_probe(struct i2c_client * client)94 static int pca9570_probe(struct i2c_client *client)
95 {
96 struct pca9570 *gpio;
97
98 gpio = devm_kzalloc(&client->dev, sizeof(*gpio), GFP_KERNEL);
99 if (!gpio)
100 return -ENOMEM;
101
102 gpio->chip.label = client->name;
103 gpio->chip.parent = &client->dev;
104 gpio->chip.owner = THIS_MODULE;
105 gpio->chip.get_direction = pca9570_get_direction;
106 gpio->chip.get = pca9570_get;
107 gpio->chip.set = pca9570_set;
108 gpio->chip.base = -1;
109 gpio->chip.ngpio = (uintptr_t)device_get_match_data(&client->dev);
110 gpio->chip.can_sleep = true;
111
112 mutex_init(&gpio->lock);
113
114 /* Read the current output level */
115 pca9570_read(gpio, &gpio->out);
116
117 i2c_set_clientdata(client, gpio);
118
119 return devm_gpiochip_add_data(&client->dev, &gpio->chip, gpio);
120 }
121
122 static const struct i2c_device_id pca9570_id_table[] = {
123 { "pca9570", 4 },
124 { /* sentinel */ }
125 };
126 MODULE_DEVICE_TABLE(i2c, pca9570_id_table);
127
128 static const struct of_device_id pca9570_of_match_table[] = {
129 { .compatible = "nxp,pca9570", .data = (void *)4 },
130 { /* sentinel */ }
131 };
132 MODULE_DEVICE_TABLE(of, pca9570_of_match_table);
133
134 static struct i2c_driver pca9570_driver = {
135 .driver = {
136 .name = "pca9570",
137 .of_match_table = pca9570_of_match_table,
138 },
139 .probe_new = pca9570_probe,
140 .id_table = pca9570_id_table,
141 };
142 module_i2c_driver(pca9570_driver);
143
144 MODULE_AUTHOR("Sungbo Eo <mans0n@gorani.run>");
145 MODULE_DESCRIPTION("GPIO expander driver for PCA9570");
146 MODULE_LICENSE("GPL v2");
147