/* drivers/input/misc/gpio_axis.c
 *
 * Copyright (C) 2007 Google, Inc.
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 */

#include <linux/kernel.h>
#include <linux/gpio.h>
#include <linux/gpio_event.h>
#include <linux/interrupt.h>

struct gpio_axis_state {
        struct input_dev *input_dev;
        struct gpio_event_axis_info *info;
        uint32_t pos;
};

uint16_t gpio_axis_4bit_gray_map_table[] = {
        [0x0] = 0x0, [0x1] = 0x1, /* 0000 0001 */
        [0x3] = 0x2, [0x2] = 0x3, /* 0011 0010 */
        [0x6] = 0x4, [0x7] = 0x5, /* 0110 0111 */
        [0x5] = 0x6, [0x4] = 0x7, /* 0101 0100 */
        [0xc] = 0x8, [0xd] = 0x9, /* 1100 1101 */
        [0xf] = 0xa, [0xe] = 0xb, /* 1111 1110 */
        [0xa] = 0xc, [0xb] = 0xd, /* 1010 1011 */
        [0x9] = 0xe, [0x8] = 0xf, /* 1001 1000 */
};
uint16_t gpio_axis_4bit_gray_map(struct gpio_event_axis_info *info, uint16_t in)
{
        return gpio_axis_4bit_gray_map_table[in];
}

uint16_t gpio_axis_5bit_singletrack_map_table[] = {
        [0x10] = 0x00, [0x14] = 0x01, [0x1c] = 0x02, /*     10000 10100 11100 */
        [0x1e] = 0x03, [0x1a] = 0x04, [0x18] = 0x05, /*     11110 11010 11000 */
        [0x08] = 0x06, [0x0a] = 0x07, [0x0e] = 0x08, /*    01000 01010 01110  */
        [0x0f] = 0x09, [0x0d] = 0x0a, [0x0c] = 0x0b, /*    01111 01101 01100  */
        [0x04] = 0x0c, [0x05] = 0x0d, [0x07] = 0x0e, /*   00100 00101 00111   */
        [0x17] = 0x0f, [0x16] = 0x10, [0x06] = 0x11, /*   10111 10110 00110   */
        [0x02] = 0x12, [0x12] = 0x13, [0x13] = 0x14, /*  00010 10010 10011    */
        [0x1b] = 0x15, [0x0b] = 0x16, [0x03] = 0x17, /*  11011 01011 00011    */
        [0x01] = 0x18, [0x09] = 0x19, [0x19] = 0x1a, /* 00001 01001 11001     */
        [0x1d] = 0x1b, [0x15] = 0x1c, [0x11] = 0x1d, /* 11101 10101 10001     */
};
uint16_t gpio_axis_5bit_singletrack_map(
        struct gpio_event_axis_info *info, uint16_t in)
{
        return gpio_axis_5bit_singletrack_map_table[in];
}

static void gpio_event_update_axis(struct gpio_axis_state *as, int report)
{
        struct gpio_event_axis_info *ai = as->info;
        int i;
        int change;
        uint16_t state = 0;
        uint16_t pos;
        uint16_t old_pos = as->pos;
        for (i = ai->count - 1; i >= 0; i--)
                state = (state << 1) | gpio_get_value(ai->gpio[i]);
        pos = ai->map(ai, state);
        if (ai->flags & GPIOEAF_PRINT_RAW)
                pr_info("axis %d-%d raw %x, pos %d -> %d\n",
                        ai->type, ai->code, state, old_pos, pos);
        if (report && pos != old_pos) {
                if (ai->type == EV_REL) {
                        change = (ai->decoded_size + pos - old_pos) %
                                  ai->decoded_size;
                        if (change > ai->decoded_size / 2)
                                change -= ai->decoded_size;
                        if (change == ai->decoded_size / 2) {
                                if (ai->flags & GPIOEAF_PRINT_EVENT)
                                        pr_info("axis %d-%d unknown direction, "
                                                "pos %d -> %d\n", ai->type,
                                                ai->code, old_pos, pos);
                                change = 0; /* no closest direction */
                        }
                        if (ai->flags & GPIOEAF_PRINT_EVENT)
                                pr_info("axis %d-%d change %d\n",
                                        ai->type, ai->code, change);
                        input_report_rel(as->input_dev, ai->code, change);
                } else {
                        if (ai->flags & GPIOEAF_PRINT_EVENT)
                                pr_info("axis %d-%d now %d\n",
                                        ai->type, ai->code, pos);
                        input_event(as->input_dev, ai->type, ai->code, pos);
                }
                input_sync(as->input_dev);
        }
        as->pos = pos;
}

static irqreturn_t gpio_axis_irq_handler(int irq, void *dev_id)
{
        struct gpio_axis_state *as = dev_id;
        gpio_event_update_axis(as, 1);
        return IRQ_HANDLED;
}

int gpio_event_axis_func(struct input_dev *input_dev,
                         struct gpio_event_info *info, void **data, int func)
{
        int ret;
        int i;
        int irq;
        struct gpio_event_axis_info *ai;
        struct gpio_axis_state *as;

        ai = container_of(info, struct gpio_event_axis_info, info);
        if (func == GPIO_EVENT_FUNC_SUSPEND) {
                for (i = 0; i < ai->count; i++)
                        disable_irq(gpio_to_irq(ai->gpio[i]));
                return 0;
        }
        if (func == GPIO_EVENT_FUNC_RESUME) {
                for (i = 0; i < ai->count; i++)
                        enable_irq(gpio_to_irq(ai->gpio[i]));
                return 0;
        }

        if (func == GPIO_EVENT_FUNC_INIT) {
                *data = as = kmalloc(sizeof(*as), GFP_KERNEL);
                if (as == NULL) {
                        ret = -ENOMEM;
                        goto err_alloc_axis_state_failed;
                }
                as->input_dev = input_dev;
                as->info = ai;

                input_set_capability(input_dev, ai->type, ai->code);
                if (ai->type == EV_ABS) {
                        input_set_abs_params(input_dev, ai->code, 0,
                                             ai->decoded_size - 1, 0, 0);
                }
                for (i = 0; i < ai->count; i++) {
                        ret = gpio_request(ai->gpio[i], "gpio_event_axis");
                        if (ret < 0)
                                goto err_request_gpio_failed;
                        ret = gpio_direction_input(ai->gpio[i]);
                        if (ret < 0)
                                goto err_gpio_direction_input_failed;
                        ret = irq = gpio_to_irq(ai->gpio[i]);
                        if (ret < 0)
                                goto err_get_irq_num_failed;
                        ret = request_irq(irq, gpio_axis_irq_handler,
                                          IRQF_TRIGGER_RISING |
                                          IRQF_TRIGGER_FALLING,
                                          "gpio_event_axis", as);
                        if (ret < 0)
                                goto err_request_irq_failed;
                }
                gpio_event_update_axis(as, 0);
                return 0;
        }

        ret = 0;
        as = *data;
        for (i = ai->count - 1; i >= 0; i--) {
                free_irq(gpio_to_irq(ai->gpio[i]), as);
err_request_irq_failed:
err_get_irq_num_failed:
err_gpio_direction_input_failed:
                gpio_free(ai->gpio[i]);
err_request_gpio_failed:
                ;
        }
        kfree(as);
        *data = NULL;
err_alloc_axis_state_failed:
        return ret;
}