// SPDX-License-Identifier: GPL-2.0
/*
 *  Turris Mox Moxtet GPIO expander
 *
 *  Copyright (C) 2018 Marek Behún <kabel@kernel.org>
 */

#include <linux/bitops.h>
#include <linux/gpio/driver.h>
#include <linux/moxtet.h>
#include <linux/module.h>

#define MOXTET_GPIO_NGPIOS      12
#define MOXTET_GPIO_INPUTS      4

struct moxtet_gpio_desc {
        u16 in_mask;
        u16 out_mask;
};

static const struct moxtet_gpio_desc descs[] = {
        [TURRIS_MOX_MODULE_SFP] = {
                .in_mask = GENMASK(2, 0),
                .out_mask = GENMASK(5, 4),
        },
};

struct moxtet_gpio_chip {
        struct device                   *dev;
        struct gpio_chip                gpio_chip;
        const struct moxtet_gpio_desc   *desc;
};

static int moxtet_gpio_get_value(struct gpio_chip *gc, unsigned int offset)
{
        struct moxtet_gpio_chip *chip = gpiochip_get_data(gc);
        int ret;

        if (chip->desc->in_mask & BIT(offset)) {
                ret = moxtet_device_read(chip->dev);
        } else if (chip->desc->out_mask & BIT(offset)) {
                ret = moxtet_device_written(chip->dev);
                if (ret >= 0)
                        ret <<= MOXTET_GPIO_INPUTS;
        } else {
                return -EINVAL;
        }

        if (ret < 0)
                return ret;

        return !!(ret & BIT(offset));
}

static int moxtet_gpio_set_value(struct gpio_chip *gc, unsigned int offset,
                                 int val)
{
        struct moxtet_gpio_chip *chip = gpiochip_get_data(gc);
        int state;

        state = moxtet_device_written(chip->dev);
        if (state < 0)
                return state;

        offset -= MOXTET_GPIO_INPUTS;

        if (val)
                state |= BIT(offset);
        else
                state &= ~BIT(offset);

        return moxtet_device_write(chip->dev, state);
}

static int moxtet_gpio_get_direction(struct gpio_chip *gc, unsigned int offset)
{
        struct moxtet_gpio_chip *chip = gpiochip_get_data(gc);

        /* All lines are hard wired to be either input or output, not both. */
        if (chip->desc->in_mask & BIT(offset))
                return GPIO_LINE_DIRECTION_IN;
        else if (chip->desc->out_mask & BIT(offset))
                return GPIO_LINE_DIRECTION_OUT;
        else
                return -EINVAL;
}

static int moxtet_gpio_direction_input(struct gpio_chip *gc,
                                       unsigned int offset)
{
        struct moxtet_gpio_chip *chip = gpiochip_get_data(gc);

        if (chip->desc->in_mask & BIT(offset))
                return 0;
        else if (chip->desc->out_mask & BIT(offset))
                return -ENOTSUPP;
        else
                return -EINVAL;
}

static int moxtet_gpio_direction_output(struct gpio_chip *gc,
                                        unsigned int offset, int val)
{
        struct moxtet_gpio_chip *chip = gpiochip_get_data(gc);

        if (chip->desc->out_mask & BIT(offset))
                return moxtet_gpio_set_value(gc, offset, val);
        else if (chip->desc->in_mask & BIT(offset))
                return -ENOTSUPP;

        return -EINVAL;
}

static int moxtet_gpio_probe(struct device *dev)
{
        struct moxtet_gpio_chip *chip;
        struct device_node *nc = dev->of_node;
        int id;

        id = to_moxtet_device(dev)->id;

        if (id >= ARRAY_SIZE(descs)) {
                dev_err(dev, "%pOF Moxtet device id 0x%x is not supported by gpio-moxtet driver\n",
                        nc, id);
                return -ENOTSUPP;
        }

        chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
        if (!chip)
                return -ENOMEM;

        chip->dev = dev;
        chip->gpio_chip.parent = dev;
        chip->desc = &descs[id];

        dev_set_drvdata(dev, chip);

        chip->gpio_chip.label = dev_name(dev);
        chip->gpio_chip.get_direction = moxtet_gpio_get_direction;
        chip->gpio_chip.direction_input = moxtet_gpio_direction_input;
        chip->gpio_chip.direction_output = moxtet_gpio_direction_output;
        chip->gpio_chip.get = moxtet_gpio_get_value;
        chip->gpio_chip.set = moxtet_gpio_set_value;
        chip->gpio_chip.base = -1;

        chip->gpio_chip.ngpio = MOXTET_GPIO_NGPIOS;

        chip->gpio_chip.can_sleep = true;
        chip->gpio_chip.owner = THIS_MODULE;

        return devm_gpiochip_add_data(dev, &chip->gpio_chip, chip);
}

static const struct of_device_id moxtet_gpio_dt_ids[] = {
        { .compatible = "cznic,moxtet-gpio", },
        {},
};
MODULE_DEVICE_TABLE(of, moxtet_gpio_dt_ids);

static const enum turris_mox_module_id moxtet_gpio_module_table[] = {
        TURRIS_MOX_MODULE_SFP,
        0,
};

static struct moxtet_driver moxtet_gpio_driver = {
        .driver = {
                .name           = "moxtet-gpio",
                .of_match_table = moxtet_gpio_dt_ids,
                .probe          = moxtet_gpio_probe,
        },
        .id_table = moxtet_gpio_module_table,
};
module_moxtet_driver(moxtet_gpio_driver);

MODULE_AUTHOR("Marek Behun <kabel@kernel.org>");
MODULE_DESCRIPTION("Turris Mox Moxtet GPIO expander");
MODULE_LICENSE("GPL v2");