drivers/gpio/gpio-104-idio-16.c

   1 /*
   2  * GPIO driver for the ACCES 104-IDIO-16 family
   3  * Copyright (C) 2015 William Breathitt Gray
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License, version 2, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  */
  14 #include <linux/device.h>
  15 #include <linux/errno.h>
  16 #include <linux/gpio/driver.h>
  17 #include <linux/io.h>
  18 #include <linux/ioport.h>
  19 #include <linux/kernel.h>
  20 #include <linux/module.h>
  21 #include <linux/moduleparam.h>
  22 #include <linux/platform_device.h>
  23 #include <linux/spinlock.h>
  24
  25 static unsigned idio_16_base;
  26 module_param(idio_16_base, uint, 0);
  27 MODULE_PARM_DESC(idio_16_base, "ACCES 104-IDIO-16 base address");
  28
  29 /**
  30  * struct idio_16_gpio - GPIO device private data structure
  31  * @chip:       instance of the gpio_chip
  32  * @lock:       synchronization lock to prevent gpio_set race conditions
  33  * @base:       base port address of the GPIO device
  34  * @extent:     extent of port address region of the GPIO device
  35  * @out_state:  output bits state
  36  */
  37 struct idio_16_gpio {
  38         struct gpio_chip chip;
  39         spinlock_t lock;
  40         unsigned base;
  41         unsigned extent;
  42         unsigned out_state;
  43 };
  44
  45 static int idio_16_gpio_get_direction(struct gpio_chip *chip, unsigned offset)
  46 {
  47         if (offset > 15)
  48                 return 1;
  49
  50         return 0;
  51 }
  52
  53 static int idio_16_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
  54 {
  55         return 0;
  56 }
  57
  58 static int idio_16_gpio_direction_output(struct gpio_chip *chip,
  59         unsigned offset, int value)
  60 {
  61         chip->set(chip, offset, value);
  62         return 0;
  63 }
  64
  65 static struct idio_16_gpio *to_idio16gpio(struct gpio_chip *gc)
  66 {
  67         return container_of(gc, struct idio_16_gpio, chip);
  68 }
  69
  70 static int idio_16_gpio_get(struct gpio_chip *chip, unsigned offset)
  71 {
  72         struct idio_16_gpio *const idio16gpio = to_idio16gpio(chip);
  73         const unsigned BIT_MASK = 1U << (offset-16);
  74
  75         if (offset < 16)
  76                 return -EINVAL;
  77
  78         if (offset < 24)
  79                 return !!(inb(idio16gpio->base + 1) & BIT_MASK);
  80
  81         return !!(inb(idio16gpio->base + 5) & (BIT_MASK>>8));
  82 }
  83
  84 static void idio_16_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
  85 {
  86         struct idio_16_gpio *const idio16gpio = to_idio16gpio(chip);
  87         const unsigned BIT_MASK = 1U << offset;
  88         unsigned long flags;
  89
  90         if (offset > 15)
  91                 return;
  92
  93         spin_lock_irqsave(&idio16gpio->lock, flags);
  94
  95         if (value)
  96                 idio16gpio->out_state |= BIT_MASK;
  97         else
  98                 idio16gpio->out_state &= ~BIT_MASK;
  99
 100         if (offset > 7)
 101                 outb(idio16gpio->out_state >> 8, idio16gpio->base + 4);
 102         else
 103                 outb(idio16gpio->out_state, idio16gpio->base);
 104
 105         spin_unlock_irqrestore(&idio16gpio->lock, flags);
 106 }
 107
 108 static int __init idio_16_probe(struct platform_device *pdev)
 109 {
 110         struct device *dev = &pdev->dev;
 111         struct idio_16_gpio *idio16gpio;
 112         int err;
 113
 114         const unsigned BASE = idio_16_base;
 115         const unsigned EXTENT = 8;
 116         const char *const NAME = dev_name(dev);
 117
 118         idio16gpio = devm_kzalloc(dev, sizeof(*idio16gpio), GFP_KERNEL);
 119         if (!idio16gpio)
 120                 return -ENOMEM;
 121
 122         if (!request_region(BASE, EXTENT, NAME)) {
 123                 dev_err(dev, "Unable to lock %s port addresses (0x%X-0x%X)\n",
 124                         NAME, BASE, BASE + EXTENT);
 125                 err = -EBUSY;
 126                 goto err_lock_io_port;
 127         }
 128
 129         idio16gpio->chip.label = NAME;
 130         idio16gpio->chip.dev = dev;
 131         idio16gpio->chip.owner = THIS_MODULE;
 132         idio16gpio->chip.base = -1;
 133         idio16gpio->chip.ngpio = 32;
 134         idio16gpio->chip.get_direction = idio_16_gpio_get_direction;
 135         idio16gpio->chip.direction_input = idio_16_gpio_direction_input;
 136         idio16gpio->chip.direction_output = idio_16_gpio_direction_output;
 137         idio16gpio->chip.get = idio_16_gpio_get;
 138         idio16gpio->chip.set = idio_16_gpio_set;
 139         idio16gpio->base = BASE;
 140         idio16gpio->extent = EXTENT;
 141         idio16gpio->out_state = 0xFFFF;
 142
 143         spin_lock_init(&idio16gpio->lock);
 144
 145         dev_set_drvdata(dev, idio16gpio);
 146
 147         err = gpiochip_add(&idio16gpio->chip);
 148         if (err) {
 149                 dev_err(dev, "GPIO registering failed (%d)\n", err);
 150                 goto err_gpio_register;
 151         }
 152
 153         return 0;
 154
 155 err_gpio_register:
 156         release_region(BASE, EXTENT);
 157 err_lock_io_port:
 158         return err;
 159 }
 160
 161 static int idio_16_remove(struct platform_device *pdev)
 162 {
 163         struct idio_16_gpio *const idio16gpio = platform_get_drvdata(pdev);
 164
 165         gpiochip_remove(&idio16gpio->chip);
 166         release_region(idio16gpio->base, idio16gpio->extent);
 167
 168         return 0;
 169 }
 170
 171 static struct platform_device *idio_16_device;
 172
 173 static struct platform_driver idio_16_driver = {
 174         .driver = {
 175                 .name = "104-idio-16"
 176         },
 177         .remove = idio_16_remove
 178 };
 179
 180 static void __exit idio_16_exit(void)
 181 {
 182         platform_device_unregister(idio_16_device);
 183         platform_driver_unregister(&idio_16_driver);
 184 }
 185
 186 static int __init idio_16_init(void)
 187 {
 188         int err;
 189
 190         idio_16_device = platform_device_alloc(idio_16_driver.driver.name, -1);
 191         if (!idio_16_device)
 192                 return -ENOMEM;
 193
 194         err = platform_device_add(idio_16_device);
 195         if (err)
 196                 goto err_platform_device;
 197
 198         err = platform_driver_probe(&idio_16_driver, idio_16_probe);
 199         if (err)
 200                 goto err_platform_driver;
 201
 202         return 0;
 203
 204 err_platform_driver:
 205         platform_device_del(idio_16_device);
 206 err_platform_device:
 207         platform_device_put(idio_16_device);
 208         return err;
 209 }
 210
 211 module_init(idio_16_init);
 212 module_exit(idio_16_exit);
 213
 214 MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
 215 MODULE_DESCRIPTION("ACCES 104-IDIO-16 GPIO driver");
 216 MODULE_LICENSE("GPL");