linux/drivers/gpio/gpio-104-idi-48.c
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   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 * This driver supports the following ACCES devices: 104-IDI-48A,
  15 * 104-IDI-48AC, 104-IDI-48B, and 104-IDI-48BC.
  16 */
  17#include <linux/bitmap.h>
  18#include <linux/bitops.h>
  19#include <linux/device.h>
  20#include <linux/errno.h>
  21#include <linux/gpio/driver.h>
  22#include <linux/io.h>
  23#include <linux/ioport.h>
  24#include <linux/interrupt.h>
  25#include <linux/irqdesc.h>
  26#include <linux/isa.h>
  27#include <linux/kernel.h>
  28#include <linux/module.h>
  29#include <linux/moduleparam.h>
  30#include <linux/spinlock.h>
  31
  32#define IDI_48_EXTENT 8
  33#define MAX_NUM_IDI_48 max_num_isa_dev(IDI_48_EXTENT)
  34
  35static unsigned int base[MAX_NUM_IDI_48];
  36static unsigned int num_idi_48;
  37module_param_hw_array(base, uint, ioport, &num_idi_48, 0);
  38MODULE_PARM_DESC(base, "ACCES 104-IDI-48 base addresses");
  39
  40static unsigned int irq[MAX_NUM_IDI_48];
  41module_param_hw_array(irq, uint, irq, NULL, 0);
  42MODULE_PARM_DESC(irq, "ACCES 104-IDI-48 interrupt line numbers");
  43
  44/**
  45 * struct idi_48_gpio - GPIO device private data structure
  46 * @chip:       instance of the gpio_chip
  47 * @lock:       synchronization lock to prevent I/O race conditions
  48 * @ack_lock:   synchronization lock to prevent IRQ handler race conditions
  49 * @irq_mask:   input bits affected by interrupts
  50 * @base:       base port address of the GPIO device
  51 * @cos_enb:    Change-Of-State IRQ enable boundaries mask
  52 */
  53struct idi_48_gpio {
  54        struct gpio_chip chip;
  55        raw_spinlock_t lock;
  56        spinlock_t ack_lock;
  57        unsigned char irq_mask[6];
  58        unsigned base;
  59        unsigned char cos_enb;
  60};
  61
  62static int idi_48_gpio_get_direction(struct gpio_chip *chip, unsigned offset)
  63{
  64        return 1;
  65}
  66
  67static int idi_48_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
  68{
  69        return 0;
  70}
  71
  72static int idi_48_gpio_get(struct gpio_chip *chip, unsigned offset)
  73{
  74        struct idi_48_gpio *const idi48gpio = gpiochip_get_data(chip);
  75        unsigned i;
  76        const unsigned register_offset[6] = { 0, 1, 2, 4, 5, 6 };
  77        unsigned base_offset;
  78        unsigned mask;
  79
  80        for (i = 0; i < 48; i += 8)
  81                if (offset < i + 8) {
  82                        base_offset = register_offset[i / 8];
  83                        mask = BIT(offset - i);
  84
  85                        return !!(inb(idi48gpio->base + base_offset) & mask);
  86                }
  87
  88        /* The following line should never execute since offset < 48 */
  89        return 0;
  90}
  91
  92static int idi_48_gpio_get_multiple(struct gpio_chip *chip, unsigned long *mask,
  93        unsigned long *bits)
  94{
  95        struct idi_48_gpio *const idi48gpio = gpiochip_get_data(chip);
  96        size_t i;
  97        static const size_t ports[] = { 0, 1, 2, 4, 5, 6 };
  98        const unsigned int gpio_reg_size = 8;
  99        unsigned int bits_offset;
 100        size_t word_index;
 101        unsigned int word_offset;
 102        unsigned long word_mask;
 103        const unsigned long port_mask = GENMASK(gpio_reg_size - 1, 0);
 104        unsigned long port_state;
 105
 106        /* clear bits array to a clean slate */
 107        bitmap_zero(bits, chip->ngpio);
 108
 109        /* get bits are evaluated a gpio port register at a time */
 110        for (i = 0; i < ARRAY_SIZE(ports); i++) {
 111                /* gpio offset in bits array */
 112                bits_offset = i * gpio_reg_size;
 113
 114                /* word index for bits array */
 115                word_index = BIT_WORD(bits_offset);
 116
 117                /* gpio offset within current word of bits array */
 118                word_offset = bits_offset % BITS_PER_LONG;
 119
 120                /* mask of get bits for current gpio within current word */
 121                word_mask = mask[word_index] & (port_mask << word_offset);
 122                if (!word_mask) {
 123                        /* no get bits in this port so skip to next one */
 124                        continue;
 125                }
 126
 127                /* read bits from current gpio port */
 128                port_state = inb(idi48gpio->base + ports[i]);
 129
 130                /* store acquired bits at respective bits array offset */
 131                bits[word_index] |= port_state << word_offset;
 132        }
 133
 134        return 0;
 135}
 136
 137static void idi_48_irq_ack(struct irq_data *data)
 138{
 139}
 140
 141static void idi_48_irq_mask(struct irq_data *data)
 142{
 143        struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
 144        struct idi_48_gpio *const idi48gpio = gpiochip_get_data(chip);
 145        const unsigned offset = irqd_to_hwirq(data);
 146        unsigned i;
 147        unsigned mask;
 148        unsigned boundary;
 149        unsigned long flags;
 150
 151        for (i = 0; i < 48; i += 8)
 152                if (offset < i + 8) {
 153                        mask = BIT(offset - i);
 154                        boundary = i / 8;
 155
 156                        idi48gpio->irq_mask[boundary] &= ~mask;
 157
 158                        if (!idi48gpio->irq_mask[boundary]) {
 159                                idi48gpio->cos_enb &= ~BIT(boundary);
 160
 161                                raw_spin_lock_irqsave(&idi48gpio->lock, flags);
 162
 163                                outb(idi48gpio->cos_enb, idi48gpio->base + 7);
 164
 165                                raw_spin_unlock_irqrestore(&idi48gpio->lock,
 166                                                           flags);
 167                        }
 168
 169                        return;
 170                }
 171}
 172
 173static void idi_48_irq_unmask(struct irq_data *data)
 174{
 175        struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
 176        struct idi_48_gpio *const idi48gpio = gpiochip_get_data(chip);
 177        const unsigned offset = irqd_to_hwirq(data);
 178        unsigned i;
 179        unsigned mask;
 180        unsigned boundary;
 181        unsigned prev_irq_mask;
 182        unsigned long flags;
 183
 184        for (i = 0; i < 48; i += 8)
 185                if (offset < i + 8) {
 186                        mask = BIT(offset - i);
 187                        boundary = i / 8;
 188                        prev_irq_mask = idi48gpio->irq_mask[boundary];
 189
 190                        idi48gpio->irq_mask[boundary] |= mask;
 191
 192                        if (!prev_irq_mask) {
 193                                idi48gpio->cos_enb |= BIT(boundary);
 194
 195                                raw_spin_lock_irqsave(&idi48gpio->lock, flags);
 196
 197                                outb(idi48gpio->cos_enb, idi48gpio->base + 7);
 198
 199                                raw_spin_unlock_irqrestore(&idi48gpio->lock,
 200                                                           flags);
 201                        }
 202
 203                        return;
 204                }
 205}
 206
 207static int idi_48_irq_set_type(struct irq_data *data, unsigned flow_type)
 208{
 209        /* The only valid irq types are none and both-edges */
 210        if (flow_type != IRQ_TYPE_NONE &&
 211                (flow_type & IRQ_TYPE_EDGE_BOTH) != IRQ_TYPE_EDGE_BOTH)
 212                return -EINVAL;
 213
 214        return 0;
 215}
 216
 217static struct irq_chip idi_48_irqchip = {
 218        .name = "104-idi-48",
 219        .irq_ack = idi_48_irq_ack,
 220        .irq_mask = idi_48_irq_mask,
 221        .irq_unmask = idi_48_irq_unmask,
 222        .irq_set_type = idi_48_irq_set_type
 223};
 224
 225static irqreturn_t idi_48_irq_handler(int irq, void *dev_id)
 226{
 227        struct idi_48_gpio *const idi48gpio = dev_id;
 228        unsigned long cos_status;
 229        unsigned long boundary;
 230        unsigned long irq_mask;
 231        unsigned long bit_num;
 232        unsigned long gpio;
 233        struct gpio_chip *const chip = &idi48gpio->chip;
 234
 235        spin_lock(&idi48gpio->ack_lock);
 236
 237        raw_spin_lock(&idi48gpio->lock);
 238
 239        cos_status = inb(idi48gpio->base + 7);
 240
 241        raw_spin_unlock(&idi48gpio->lock);
 242
 243        /* IRQ Status (bit 6) is active low (0 = IRQ generated by device) */
 244        if (cos_status & BIT(6)) {
 245                spin_unlock(&idi48gpio->ack_lock);
 246                return IRQ_NONE;
 247        }
 248
 249        /* Bit 0-5 indicate which Change-Of-State boundary triggered the IRQ */
 250        cos_status &= 0x3F;
 251
 252        for_each_set_bit(boundary, &cos_status, 6) {
 253                irq_mask = idi48gpio->irq_mask[boundary];
 254
 255                for_each_set_bit(bit_num, &irq_mask, 8) {
 256                        gpio = bit_num + boundary * 8;
 257
 258                        generic_handle_irq(irq_find_mapping(chip->irq.domain,
 259                                gpio));
 260                }
 261        }
 262
 263        spin_unlock(&idi48gpio->ack_lock);
 264
 265        return IRQ_HANDLED;
 266}
 267
 268#define IDI48_NGPIO 48
 269static const char *idi48_names[IDI48_NGPIO] = {
 270        "Bit 0 A", "Bit 1 A", "Bit 2 A", "Bit 3 A", "Bit 4 A", "Bit 5 A",
 271        "Bit 6 A", "Bit 7 A", "Bit 8 A", "Bit 9 A", "Bit 10 A", "Bit 11 A",
 272        "Bit 12 A", "Bit 13 A", "Bit 14 A", "Bit 15 A", "Bit 16 A", "Bit 17 A",
 273        "Bit 18 A", "Bit 19 A", "Bit 20 A", "Bit 21 A", "Bit 22 A", "Bit 23 A",
 274        "Bit 0 B", "Bit 1 B", "Bit 2 B", "Bit 3 B", "Bit 4 B", "Bit 5 B",
 275        "Bit 6 B", "Bit 7 B", "Bit 8 B", "Bit 9 B", "Bit 10 B", "Bit 11 B",
 276        "Bit 12 B", "Bit 13 B", "Bit 14 B", "Bit 15 B", "Bit 16 B", "Bit 17 B",
 277        "Bit 18 B", "Bit 19 B", "Bit 20 B", "Bit 21 B", "Bit 22 B", "Bit 23 B"
 278};
 279
 280static int idi_48_probe(struct device *dev, unsigned int id)
 281{
 282        struct idi_48_gpio *idi48gpio;
 283        const char *const name = dev_name(dev);
 284        int err;
 285
 286        idi48gpio = devm_kzalloc(dev, sizeof(*idi48gpio), GFP_KERNEL);
 287        if (!idi48gpio)
 288                return -ENOMEM;
 289
 290        if (!devm_request_region(dev, base[id], IDI_48_EXTENT, name)) {
 291                dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n",
 292                        base[id], base[id] + IDI_48_EXTENT);
 293                return -EBUSY;
 294        }
 295
 296        idi48gpio->chip.label = name;
 297        idi48gpio->chip.parent = dev;
 298        idi48gpio->chip.owner = THIS_MODULE;
 299        idi48gpio->chip.base = -1;
 300        idi48gpio->chip.ngpio = IDI48_NGPIO;
 301        idi48gpio->chip.names = idi48_names;
 302        idi48gpio->chip.get_direction = idi_48_gpio_get_direction;
 303        idi48gpio->chip.direction_input = idi_48_gpio_direction_input;
 304        idi48gpio->chip.get = idi_48_gpio_get;
 305        idi48gpio->chip.get_multiple = idi_48_gpio_get_multiple;
 306        idi48gpio->base = base[id];
 307
 308        raw_spin_lock_init(&idi48gpio->lock);
 309        spin_lock_init(&idi48gpio->ack_lock);
 310
 311        err = devm_gpiochip_add_data(dev, &idi48gpio->chip, idi48gpio);
 312        if (err) {
 313                dev_err(dev, "GPIO registering failed (%d)\n", err);
 314                return err;
 315        }
 316
 317        /* Disable IRQ by default */
 318        outb(0, base[id] + 7);
 319        inb(base[id] + 7);
 320
 321        err = gpiochip_irqchip_add(&idi48gpio->chip, &idi_48_irqchip, 0,
 322                handle_edge_irq, IRQ_TYPE_NONE);
 323        if (err) {
 324                dev_err(dev, "Could not add irqchip (%d)\n", err);
 325                return err;
 326        }
 327
 328        err = devm_request_irq(dev, irq[id], idi_48_irq_handler, IRQF_SHARED,
 329                name, idi48gpio);
 330        if (err) {
 331                dev_err(dev, "IRQ handler registering failed (%d)\n", err);
 332                return err;
 333        }
 334
 335        return 0;
 336}
 337
 338static struct isa_driver idi_48_driver = {
 339        .probe = idi_48_probe,
 340        .driver = {
 341                .name = "104-idi-48"
 342        },
 343};
 344module_isa_driver(idi_48_driver, num_idi_48);
 345
 346MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
 347MODULE_DESCRIPTION("ACCES 104-IDI-48 GPIO driver");
 348MODULE_LICENSE("GPL v2");
 349