// SPDX-License-Identifier: GPL-2.0-only
/*
 * sl28cpld GPIO driver
 *
 * Copyright 2020 Michael Walle <michael@walle.cc>
 */

#include <linux/device.h>
#include <linux/gpio/driver.h>
#include <linux/gpio/regmap.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>

/* GPIO flavor */
#define GPIO_REG_DIR    0x00
#define GPIO_REG_OUT    0x01
#define GPIO_REG_IN     0x02
#define GPIO_REG_IE     0x03
#define GPIO_REG_IP     0x04

/* input-only flavor */
#define GPI_REG_IN      0x00

/* output-only flavor */
#define GPO_REG_OUT     0x00

enum sl28cpld_gpio_type {
        SL28CPLD_GPIO = 1,
        SL28CPLD_GPI,
        SL28CPLD_GPO,
};

static const struct regmap_irq sl28cpld_gpio_irqs[] = {
        REGMAP_IRQ_REG_LINE(0, 8),
        REGMAP_IRQ_REG_LINE(1, 8),
        REGMAP_IRQ_REG_LINE(2, 8),
        REGMAP_IRQ_REG_LINE(3, 8),
        REGMAP_IRQ_REG_LINE(4, 8),
        REGMAP_IRQ_REG_LINE(5, 8),
        REGMAP_IRQ_REG_LINE(6, 8),
        REGMAP_IRQ_REG_LINE(7, 8),
};

static int sl28cpld_gpio_irq_init(struct platform_device *pdev,
                                  unsigned int base,
                                  struct gpio_regmap_config *config)
{
        struct regmap_irq_chip_data *irq_data;
        struct regmap_irq_chip *irq_chip;
        struct device *dev = &pdev->dev;
        int irq, ret;

        if (!device_property_read_bool(dev, "interrupt-controller"))
                return 0;

        irq = platform_get_irq(pdev, 0);
        if (irq < 0)
                return irq;

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

        irq_chip->name = "sl28cpld-gpio-irq";
        irq_chip->irqs = sl28cpld_gpio_irqs;
        irq_chip->num_irqs = ARRAY_SIZE(sl28cpld_gpio_irqs);
        irq_chip->num_regs = 1;
        irq_chip->status_base = base + GPIO_REG_IP;
        irq_chip->unmask_base = base + GPIO_REG_IE;
        irq_chip->ack_base = base + GPIO_REG_IP;

        ret = devm_regmap_add_irq_chip_fwnode(dev, dev_fwnode(dev),
                                              config->regmap, irq,
                                              IRQF_SHARED | IRQF_ONESHOT,
                                              0, irq_chip, &irq_data);
        if (ret)
                return ret;

        config->irq_domain = regmap_irq_get_domain(irq_data);

        return 0;
}

static int sl28cpld_gpio_probe(struct platform_device *pdev)
{
        struct gpio_regmap_config config = {0};
        enum sl28cpld_gpio_type type;
        struct regmap *regmap;
        u32 base;
        int ret;

        if (!pdev->dev.parent)
                return -ENODEV;

        type = (uintptr_t)device_get_match_data(&pdev->dev);
        if (!type)
                return -ENODEV;

        ret = device_property_read_u32(&pdev->dev, "reg", &base);
        if (ret)
                return -EINVAL;

        regmap = dev_get_regmap(pdev->dev.parent, NULL);
        if (!regmap)
                return -ENODEV;

        config.regmap = regmap;
        config.parent = &pdev->dev;
        config.ngpio = 8;

        switch (type) {
        case SL28CPLD_GPIO:
                config.reg_dat_base = base + GPIO_REG_IN;
                config.reg_set_base = base + GPIO_REG_OUT;
                /* reg_dir_out_base might be zero */
                config.reg_dir_out_base = GPIO_REGMAP_ADDR(base + GPIO_REG_DIR);

                /* This type supports interrupts */
                ret = sl28cpld_gpio_irq_init(pdev, base, &config);
                if (ret)
                        return ret;
                break;
        case SL28CPLD_GPO:
                config.reg_set_base = base + GPO_REG_OUT;
                break;
        case SL28CPLD_GPI:
                config.reg_dat_base = base + GPI_REG_IN;
                break;
        default:
                dev_err(&pdev->dev, "unknown type %d\n", type);
                return -ENODEV;
        }

        return PTR_ERR_OR_ZERO(devm_gpio_regmap_register(&pdev->dev, &config));
}

static const struct of_device_id sl28cpld_gpio_of_match[] = {
        { .compatible = "kontron,sl28cpld-gpio", .data = (void *)SL28CPLD_GPIO },
        { .compatible = "kontron,sl28cpld-gpi", .data = (void *)SL28CPLD_GPI },
        { .compatible = "kontron,sl28cpld-gpo", .data = (void *)SL28CPLD_GPO },
        {}
};
MODULE_DEVICE_TABLE(of, sl28cpld_gpio_of_match);

static struct platform_driver sl28cpld_gpio_driver = {
        .probe = sl28cpld_gpio_probe,
        .driver = {
                .name = "sl28cpld-gpio",
                .of_match_table = sl28cpld_gpio_of_match,
        },
};
module_platform_driver(sl28cpld_gpio_driver);

MODULE_DESCRIPTION("sl28cpld GPIO Driver");
MODULE_AUTHOR("Michael Walle <michael@walle.cc>");
MODULE_LICENSE("GPL");