drivers/gpio/gpio-pca9570.c

   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
  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
  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
  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
  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
  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
  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");