drivers/gpio/gpio-104-idi-48.c

   1 /*
   2  * GPIO driver for the ACCES 104-IDI-48 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/bitops.h>
  15 #include <linux/device.h>
  16 #include <linux/errno.h>
  17 #include <linux/gpio/driver.h>
  18 #include <linux/io.h>
  19 #include <linux/ioport.h>
  20 #include <linux/interrupt.h>
  21 #include <linux/irqdesc.h>
  22 #include <linux/kernel.h>
  23 #include <linux/module.h>
  24 #include <linux/moduleparam.h>
  25 #include <linux/platform_device.h>
  26 #include <linux/spinlock.h>
  27
  28 static unsigned idi_48_base;
  29 module_param(idi_48_base, uint, 0);
  30 MODULE_PARM_DESC(idi_48_base, "ACCES 104-IDI-48 base address");
  31 static unsigned idi_48_irq;
  32 module_param(idi_48_irq, uint, 0);
  33 MODULE_PARM_DESC(idi_48_irq, "ACCES 104-IDI-48 interrupt line number");
  34
  35 /**
  36  * struct idi_48_gpio - GPIO device private data structure
  37  * @chip:       instance of the gpio_chip
  38  * @lock:       synchronization lock to prevent I/O race conditions
  39  * @ack_lock:   synchronization lock to prevent IRQ handler race conditions
  40  * @irq_mask:   input bits affected by interrupts
  41  * @base:       base port address of the GPIO device
  42  * @irq:        Interrupt line number
  43  * @cos_enb:    Change-Of-State IRQ enable boundaries mask
  44  */
  45 struct idi_48_gpio {
  46         struct gpio_chip chip;
  47         spinlock_t lock;
  48         spinlock_t ack_lock;
  49         unsigned char irq_mask[6];
  50         unsigned base;
  51         unsigned irq;
  52         unsigned char cos_enb;
  53 };
  54
  55 static int idi_48_gpio_get_direction(struct gpio_chip *chip, unsigned offset)
  56 {
  57         return 1;
  58 }
  59
  60 static int idi_48_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
  61 {
  62         return 0;
  63 }
  64
  65 static int idi_48_gpio_get(struct gpio_chip *chip, unsigned offset)
  66 {
  67         struct idi_48_gpio *const idi48gpio = gpiochip_get_data(chip);
  68         unsigned i;
  69         const unsigned register_offset[6] = { 0, 1, 2, 4, 5, 6 };
  70         unsigned base_offset;
  71         unsigned mask;
  72
  73         for (i = 0; i < 48; i += 8)
  74                 if (offset < i + 8) {
  75                         base_offset = register_offset[i / 8];
  76                         mask = BIT(offset - i);
  77
  78                         return !!(inb(idi48gpio->base + base_offset) & mask);
  79                 }
  80
  81         /* The following line should never execute since offset < 48 */
  82         return 0;
  83 }
  84
  85 static void idi_48_irq_ack(struct irq_data *data)
  86 {
  87 }
  88
  89 static void idi_48_irq_mask(struct irq_data *data)
  90 {
  91         struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
  92         struct idi_48_gpio *const idi48gpio = gpiochip_get_data(chip);
  93         const unsigned offset = irqd_to_hwirq(data);
  94         unsigned i;
  95         unsigned mask;
  96         unsigned boundary;
  97         unsigned long flags;
  98
  99         for (i = 0; i < 48; i += 8)
 100                 if (offset < i + 8) {
 101                         mask = BIT(offset - i);
 102                         boundary = i / 8;
 103
 104                         idi48gpio->irq_mask[boundary] &= ~mask;
 105
 106                         if (!idi48gpio->irq_mask[boundary]) {
 107                                 idi48gpio->cos_enb &= ~BIT(boundary);
 108
 109                                 spin_lock_irqsave(&idi48gpio->lock, flags);
 110
 111                                 outb(idi48gpio->cos_enb, idi48gpio->base + 7);
 112
 113                                 spin_unlock_irqrestore(&idi48gpio->lock, flags);
 114                         }
 115
 116                         return;
 117                 }
 118 }
 119
 120 static void idi_48_irq_unmask(struct irq_data *data)
 121 {
 122         struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
 123         struct idi_48_gpio *const idi48gpio = gpiochip_get_data(chip);
 124         const unsigned offset = irqd_to_hwirq(data);
 125         unsigned i;
 126         unsigned mask;
 127         unsigned boundary;
 128         unsigned prev_irq_mask;
 129         unsigned long flags;
 130
 131         for (i = 0; i < 48; i += 8)
 132                 if (offset < i + 8) {
 133                         mask = BIT(offset - i);
 134                         boundary = i / 8;
 135                         prev_irq_mask = idi48gpio->irq_mask[boundary];
 136
 137                         idi48gpio->irq_mask[boundary] |= mask;
 138
 139                         if (!prev_irq_mask) {
 140                                 idi48gpio->cos_enb |= BIT(boundary);
 141
 142                                 spin_lock_irqsave(&idi48gpio->lock, flags);
 143
 144                                 outb(idi48gpio->cos_enb, idi48gpio->base + 7);
 145
 146                                 spin_unlock_irqrestore(&idi48gpio->lock, flags);
 147                         }
 148
 149                         return;
 150                 }
 151 }
 152
 153 static int idi_48_irq_set_type(struct irq_data *data, unsigned flow_type)
 154 {
 155         /* The only valid irq types are none and both-edges */
 156         if (flow_type != IRQ_TYPE_NONE &&
 157                 (flow_type & IRQ_TYPE_EDGE_BOTH) != IRQ_TYPE_EDGE_BOTH)
 158                 return -EINVAL;
 159
 160         return 0;
 161 }
 162
 163 static struct irq_chip idi_48_irqchip = {
 164         .name = "104-idi-48",
 165         .irq_ack = idi_48_irq_ack,
 166         .irq_mask = idi_48_irq_mask,
 167         .irq_unmask = idi_48_irq_unmask,
 168         .irq_set_type = idi_48_irq_set_type
 169 };
 170
 171 static irqreturn_t idi_48_irq_handler(int irq, void *dev_id)
 172 {
 173         struct idi_48_gpio *const idi48gpio = dev_id;
 174         unsigned long cos_status;
 175         unsigned long boundary;
 176         unsigned long irq_mask;
 177         unsigned long bit_num;
 178         unsigned long gpio;
 179         struct gpio_chip *const chip = &idi48gpio->chip;
 180
 181         spin_lock(&idi48gpio->ack_lock);
 182
 183         spin_lock(&idi48gpio->lock);
 184
 185         cos_status = inb(idi48gpio->base + 7);
 186
 187         spin_unlock(&idi48gpio->lock);
 188
 189         /* IRQ Status (bit 6) is active low (0 = IRQ generated by device) */
 190         if (cos_status & BIT(6)) {
 191                 spin_unlock(&idi48gpio->ack_lock);
 192                 return IRQ_NONE;
 193         }
 194
 195         /* Bit 0-5 indicate which Change-Of-State boundary triggered the IRQ */
 196         cos_status &= 0x3F;
 197
 198         for_each_set_bit(boundary, &cos_status, 6) {
 199                 irq_mask = idi48gpio->irq_mask[boundary];
 200
 201                 for_each_set_bit(bit_num, &irq_mask, 8) {
 202                         gpio = bit_num + boundary * 8;
 203
 204                         generic_handle_irq(irq_find_mapping(chip->irqdomain,
 205                                 gpio));
 206                 }
 207         }
 208
 209         spin_unlock(&idi48gpio->ack_lock);
 210
 211         return IRQ_HANDLED;
 212 }
 213
 214 static int __init idi_48_probe(struct platform_device *pdev)
 215 {
 216         struct device *dev = &pdev->dev;
 217         struct idi_48_gpio *idi48gpio;
 218         const unsigned base = idi_48_base;
 219         const unsigned extent = 8;
 220         const char *const name = dev_name(dev);
 221         int err;
 222         const unsigned irq = idi_48_irq;
 223
 224         idi48gpio = devm_kzalloc(dev, sizeof(*idi48gpio), GFP_KERNEL);
 225         if (!idi48gpio)
 226                 return -ENOMEM;
 227
 228         if (!devm_request_region(dev, base, extent, name)) {
 229                 dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n",
 230                         base, base + extent);
 231                 return -EBUSY;
 232         }
 233
 234         idi48gpio->chip.label = name;
 235         idi48gpio->chip.parent = dev;
 236         idi48gpio->chip.owner = THIS_MODULE;
 237         idi48gpio->chip.base = -1;
 238         idi48gpio->chip.ngpio = 48;
 239         idi48gpio->chip.get_direction = idi_48_gpio_get_direction;
 240         idi48gpio->chip.direction_input = idi_48_gpio_direction_input;
 241         idi48gpio->chip.get = idi_48_gpio_get;
 242         idi48gpio->base = base;
 243         idi48gpio->irq = irq;
 244
 245         spin_lock_init(&idi48gpio->lock);
 246
 247         dev_set_drvdata(dev, idi48gpio);
 248
 249         err = gpiochip_add_data(&idi48gpio->chip, idi48gpio);
 250         if (err) {
 251                 dev_err(dev, "GPIO registering failed (%d)\n", err);
 252                 return err;
 253         }
 254
 255         /* Disable IRQ by default */
 256         outb(0, base + 7);
 257         inb(base + 7);
 258
 259         err = gpiochip_irqchip_add(&idi48gpio->chip, &idi_48_irqchip, 0,
 260                 handle_edge_irq, IRQ_TYPE_NONE);
 261         if (err) {
 262                 dev_err(dev, "Could not add irqchip (%d)\n", err);
 263                 goto err_gpiochip_remove;
 264         }
 265
 266         err = request_irq(irq, idi_48_irq_handler, IRQF_SHARED, name,
 267                 idi48gpio);
 268         if (err) {
 269                 dev_err(dev, "IRQ handler registering failed (%d)\n", err);
 270                 goto err_gpiochip_remove;
 271         }
 272
 273         return 0;
 274
 275 err_gpiochip_remove:
 276         gpiochip_remove(&idi48gpio->chip);
 277         return err;
 278 }
 279
 280 static int idi_48_remove(struct platform_device *pdev)
 281 {
 282         struct idi_48_gpio *const idi48gpio = platform_get_drvdata(pdev);
 283
 284         free_irq(idi48gpio->irq, idi48gpio);
 285         gpiochip_remove(&idi48gpio->chip);
 286
 287         return 0;
 288 }
 289
 290 static struct platform_device *idi_48_device;
 291
 292 static struct platform_driver idi_48_driver = {
 293         .driver = {
 294                 .name = "104-idi-48"
 295         },
 296         .remove = idi_48_remove
 297 };
 298
 299 static void __exit idi_48_exit(void)
 300 {
 301         platform_device_unregister(idi_48_device);
 302         platform_driver_unregister(&idi_48_driver);
 303 }
 304
 305 static int __init idi_48_init(void)
 306 {
 307         int err;
 308
 309         idi_48_device = platform_device_alloc(idi_48_driver.driver.name, -1);
 310         if (!idi_48_device)
 311                 return -ENOMEM;
 312
 313         err = platform_device_add(idi_48_device);
 314         if (err)
 315                 goto err_platform_device;
 316
 317         err = platform_driver_probe(&idi_48_driver, idi_48_probe);
 318         if (err)
 319                 goto err_platform_driver;
 320
 321         return 0;
 322
 323 err_platform_driver:
 324         platform_device_del(idi_48_device);
 325 err_platform_device:
 326         platform_device_put(idi_48_device);
 327         return err;
 328 }
 329
 330 module_init(idi_48_init);
 331 module_exit(idi_48_exit);
 332
 333 MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
 334 MODULE_DESCRIPTION("ACCES 104-IDI-48 GPIO driver");
 335 MODULE_LICENSE("GPL v2");