// SPDX-License-Identifier: GPL-2.0-only
/*
 * MEN 16Z127 GPIO driver
 *
 * Copyright (C) 2016 MEN Mikroelektronik GmbH (www.men.de)
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/io.h>
#include <linux/err.h>
#include <linux/mcb.h>
#include <linux/bitops.h>
#include <linux/gpio/driver.h>
#include <linux/gpio/generic.h>

#define MEN_Z127_CTRL   0x00
#define MEN_Z127_PSR    0x04
#define MEN_Z127_IRQR   0x08
#define MEN_Z127_GPIODR 0x0c
#define MEN_Z127_IER1   0x10
#define MEN_Z127_IER2   0x14
#define MEN_Z127_DBER   0x18
#define MEN_Z127_ODER   0x1C
#define GPIO_TO_DBCNT_REG(gpio) ((gpio * 4) + 0x80)

/* MEN Z127 supported model ids*/
#define MEN_Z127_ID     0x7f
#define MEN_Z034_ID     0x22
#define MEN_Z037_ID     0x25

#define MEN_Z127_DB_MIN_US      50
/* 16 bit compare register. Each bit represents 50us */
#define MEN_Z127_DB_MAX_US      (0xffff * MEN_Z127_DB_MIN_US)
#define MEN_Z127_DB_IN_RANGE(db)        ((db >= MEN_Z127_DB_MIN_US) && \
                                         (db <= MEN_Z127_DB_MAX_US))

struct men_z127_gpio {
        struct gpio_generic_chip chip;
        void __iomem *reg_base;
        struct resource *mem;
};

static int men_z127_debounce(struct gpio_chip *gc, unsigned gpio,
                             unsigned debounce)
{
        struct men_z127_gpio *priv = gpiochip_get_data(gc);
        struct device *dev = gc->parent;
        unsigned int rnd;
        u32 db_en, db_cnt;

        if (!MEN_Z127_DB_IN_RANGE(debounce)) {
                dev_err(dev, "debounce value %u out of range", debounce);
                return -EINVAL;
        }

        if (debounce > 0) {
                /* round up or down depending on MSB-1 */
                rnd = fls(debounce) - 1;

                if (rnd && (debounce & BIT(rnd - 1)))
                        debounce = roundup(debounce, MEN_Z127_DB_MIN_US);
                else
                        debounce = rounddown(debounce, MEN_Z127_DB_MIN_US);

                if (debounce > MEN_Z127_DB_MAX_US)
                        debounce = MEN_Z127_DB_MAX_US;

                /* 50us per register unit */
                debounce /= 50;
        }

        guard(gpio_generic_lock)(&priv->chip);

        db_en = readl(priv->reg_base + MEN_Z127_DBER);

        if (debounce == 0) {
                db_en &= ~BIT(gpio);
                db_cnt = 0;
        } else {
                db_en |= BIT(gpio);
                db_cnt = debounce;
        }

        writel(db_en, priv->reg_base + MEN_Z127_DBER);
        writel(db_cnt, priv->reg_base + GPIO_TO_DBCNT_REG(gpio));

        return 0;
}

static int men_z127_set_single_ended(struct gpio_chip *gc,
                                     unsigned offset,
                                     enum pin_config_param param)
{
        struct men_z127_gpio *priv = gpiochip_get_data(gc);
        u32 od_en;

        guard(gpio_generic_lock)(&priv->chip);

        od_en = readl(priv->reg_base + MEN_Z127_ODER);

        if (param == PIN_CONFIG_DRIVE_OPEN_DRAIN)
                od_en |= BIT(offset);
        else
                /* Implicitly PIN_CONFIG_DRIVE_PUSH_PULL */
                od_en &= ~BIT(offset);

        writel(od_en, priv->reg_base + MEN_Z127_ODER);

        return 0;
}

static int men_z127_set_config(struct gpio_chip *gc, unsigned offset,
                               unsigned long config)
{
        enum pin_config_param param = pinconf_to_config_param(config);

        switch (param) {
        case PIN_CONFIG_DRIVE_OPEN_DRAIN:
        case PIN_CONFIG_DRIVE_PUSH_PULL:
                return men_z127_set_single_ended(gc, offset, param);

        case PIN_CONFIG_INPUT_DEBOUNCE:
                return men_z127_debounce(gc, offset,
                        pinconf_to_config_argument(config));

        default:
                break;
        }

        return -ENOTSUPP;
}

static void men_z127_release_mem(void *data)
{
        struct resource *res = data;

        mcb_release_mem(res);
}

static int men_z127_probe(struct mcb_device *mdev,
                          const struct mcb_device_id *id)
{
        struct gpio_generic_chip_config config;
        struct men_z127_gpio *men_z127_gpio;
        struct device *dev = &mdev->dev;
        int ret;
        unsigned long sz;

        men_z127_gpio = devm_kzalloc(dev, sizeof(struct men_z127_gpio),
                                     GFP_KERNEL);
        if (!men_z127_gpio)
                return -ENOMEM;

        men_z127_gpio->mem = mcb_request_mem(mdev, dev_name(dev));
        if (IS_ERR(men_z127_gpio->mem))
                return dev_err_probe(dev, PTR_ERR(men_z127_gpio->mem),
                                     "failed to request device memory");

        ret = devm_add_action_or_reset(dev, men_z127_release_mem,
                                       men_z127_gpio->mem);
        if (ret)
                return ret;

        men_z127_gpio->reg_base = devm_ioremap(dev, men_z127_gpio->mem->start,
                                        resource_size(men_z127_gpio->mem));
        if (men_z127_gpio->reg_base == NULL)
                return -ENXIO;

        mcb_set_drvdata(mdev, men_z127_gpio);

        switch (mdev->id) {
        case MEN_Z127_ID:
                sz = 4;
                break;
        case MEN_Z034_ID:
        case MEN_Z037_ID:
                sz = 1;
                break;
        default:
                return dev_err_probe(&mdev->dev, -EINVAL, "no size found for id %d", mdev->id);
        }

        config = (struct gpio_generic_chip_config) {
                .dev = &mdev->dev,
                .sz = sz,
                .dat = men_z127_gpio->reg_base + MEN_Z127_PSR,
                .set = men_z127_gpio->reg_base + MEN_Z127_CTRL,
                .dirout = men_z127_gpio->reg_base + MEN_Z127_GPIODR,
        };

        ret = gpio_generic_chip_init(&men_z127_gpio->chip, &config);
        if (ret)
                return ret;

        men_z127_gpio->chip.gc.set_config = men_z127_set_config;

        ret = devm_gpiochip_add_data(dev, &men_z127_gpio->chip.gc, men_z127_gpio);
        if (ret)
                return dev_err_probe(dev, ret,
                        "failed to register MEN 16Z127 GPIO controller");

        return 0;
}

static const struct mcb_device_id men_z127_ids[] = {
        { .device = MEN_Z127_ID },
        { .device = MEN_Z034_ID },
        { .device = MEN_Z037_ID },
        { }
};
MODULE_DEVICE_TABLE(mcb, men_z127_ids);

static struct mcb_driver men_z127_driver = {
        .driver = {
                .name = "z127-gpio",
        },
        .probe = men_z127_probe,
        .id_table = men_z127_ids,
};
module_mcb_driver(men_z127_driver);

MODULE_AUTHOR("Andreas Werner <andreas.werner@men.de>");
MODULE_DESCRIPTION("MEN GPIO Controller");
MODULE_LICENSE("GPL v2");
MODULE_IMPORT_NS("MCB");