// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2013 Altera Corporation
 * Based on gpio-mpc8xxx.c
 */

#include <linux/bitops.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/spinlock.h>
#include <linux/types.h>

#include <linux/gpio/driver.h>

#define ALTERA_GPIO_MAX_NGPIO           32
#define ALTERA_GPIO_DATA                0x0
#define ALTERA_GPIO_DIR                 0x4
#define ALTERA_GPIO_IRQ_MASK            0x8
#define ALTERA_GPIO_EDGE_CAP            0xc

/**
* struct altera_gpio_chip
* @gc                   : GPIO chip structure.
* @regs                 : memory mapped IO address for the controller registers.
* @gpio_lock            : synchronization lock so that new irq/set/get requests
*                         will be blocked until the current one completes.
* @interrupt_trigger    : specifies the hardware configured IRQ trigger type
*                         (rising, falling, both, high)
*/
struct altera_gpio_chip {
        struct gpio_chip gc;
        void __iomem *regs;
        raw_spinlock_t gpio_lock;
        int interrupt_trigger;
};

static void altera_gpio_irq_unmask(struct irq_data *d)
{
        struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
        struct altera_gpio_chip *altera_gc = gpiochip_get_data(gc);
        unsigned long flags;
        u32 intmask;

        gpiochip_enable_irq(gc, irqd_to_hwirq(d));

        raw_spin_lock_irqsave(&altera_gc->gpio_lock, flags);
        intmask = readl(altera_gc->regs + ALTERA_GPIO_IRQ_MASK);
        /* Set ALTERA_GPIO_IRQ_MASK bit to unmask */
        intmask |= BIT(irqd_to_hwirq(d));
        writel(intmask, altera_gc->regs + ALTERA_GPIO_IRQ_MASK);
        raw_spin_unlock_irqrestore(&altera_gc->gpio_lock, flags);
}

static void altera_gpio_irq_mask(struct irq_data *d)
{
        struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
        struct altera_gpio_chip *altera_gc = gpiochip_get_data(gc);
        unsigned long flags;
        u32 intmask;

        raw_spin_lock_irqsave(&altera_gc->gpio_lock, flags);
        intmask = readl(altera_gc->regs + ALTERA_GPIO_IRQ_MASK);
        /* Clear ALTERA_GPIO_IRQ_MASK bit to mask */
        intmask &= ~BIT(irqd_to_hwirq(d));
        writel(intmask, altera_gc->regs + ALTERA_GPIO_IRQ_MASK);
        raw_spin_unlock_irqrestore(&altera_gc->gpio_lock, flags);

        gpiochip_disable_irq(gc, irqd_to_hwirq(d));
}

/*
 * This controller's IRQ type is synthesized in hardware, so this function
 * just checks if the requested set_type matches the synthesized IRQ type
 */
static int altera_gpio_irq_set_type(struct irq_data *d,
                                   unsigned int type)
{
        struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
        struct altera_gpio_chip *altera_gc = gpiochip_get_data(gc);

        if (type == IRQ_TYPE_NONE) {
                irq_set_handler_locked(d, handle_bad_irq);
                return 0;
        }
        if (type == altera_gc->interrupt_trigger) {
                if (type == IRQ_TYPE_LEVEL_HIGH)
                        irq_set_handler_locked(d, handle_level_irq);
                else
                        irq_set_handler_locked(d, handle_simple_irq);
                return 0;
        }
        irq_set_handler_locked(d, handle_bad_irq);
        return -EINVAL;
}

static unsigned int altera_gpio_irq_startup(struct irq_data *d)
{
        altera_gpio_irq_unmask(d);

        return 0;
}

static int altera_gpio_get(struct gpio_chip *gc, unsigned offset)
{
        struct altera_gpio_chip *altera_gc = gpiochip_get_data(gc);

        return !!(readl(altera_gc->regs + ALTERA_GPIO_DATA) & BIT(offset));
}

static int altera_gpio_set(struct gpio_chip *gc, unsigned int offset, int value)
{
        struct altera_gpio_chip *altera_gc = gpiochip_get_data(gc);
        unsigned long flags;
        unsigned int data_reg;

        raw_spin_lock_irqsave(&altera_gc->gpio_lock, flags);
        data_reg = readl(altera_gc->regs + ALTERA_GPIO_DATA);
        if (value)
                data_reg |= BIT(offset);
        else
                data_reg &= ~BIT(offset);
        writel(data_reg, altera_gc->regs + ALTERA_GPIO_DATA);
        raw_spin_unlock_irqrestore(&altera_gc->gpio_lock, flags);

        return 0;
}

static int altera_gpio_direction_input(struct gpio_chip *gc, unsigned offset)
{
        struct altera_gpio_chip *altera_gc = gpiochip_get_data(gc);
        unsigned long flags;
        unsigned int gpio_ddr;

        raw_spin_lock_irqsave(&altera_gc->gpio_lock, flags);
        /* Set pin as input, assumes software controlled IP */
        gpio_ddr = readl(altera_gc->regs + ALTERA_GPIO_DIR);
        gpio_ddr &= ~BIT(offset);
        writel(gpio_ddr, altera_gc->regs + ALTERA_GPIO_DIR);
        raw_spin_unlock_irqrestore(&altera_gc->gpio_lock, flags);

        return 0;
}

static int altera_gpio_direction_output(struct gpio_chip *gc,
                unsigned offset, int value)
{
        struct altera_gpio_chip *altera_gc = gpiochip_get_data(gc);
        unsigned long flags;
        unsigned int data_reg, gpio_ddr;

        raw_spin_lock_irqsave(&altera_gc->gpio_lock, flags);
        /* Sets the GPIO value */
        data_reg = readl(altera_gc->regs + ALTERA_GPIO_DATA);
        if (value)
                data_reg |= BIT(offset);
        else
                data_reg &= ~BIT(offset);
        writel(data_reg, altera_gc->regs + ALTERA_GPIO_DATA);

        /* Set pin as output, assumes software controlled IP */
        gpio_ddr = readl(altera_gc->regs + ALTERA_GPIO_DIR);
        gpio_ddr |= BIT(offset);
        writel(gpio_ddr, altera_gc->regs + ALTERA_GPIO_DIR);
        raw_spin_unlock_irqrestore(&altera_gc->gpio_lock, flags);

        return 0;
}

static void altera_gpio_irq_edge_handler(struct irq_desc *desc)
{
        struct gpio_chip *gc = irq_desc_get_handler_data(desc);
        struct altera_gpio_chip *altera_gc = gpiochip_get_data(gc);
        struct irq_domain *irqdomain = gc->irq.domain;
        struct irq_chip *chip;
        unsigned long status;
        int i;

        chip = irq_desc_get_chip(desc);

        chained_irq_enter(chip, desc);

        while ((status =
                (readl(altera_gc->regs + ALTERA_GPIO_EDGE_CAP) &
                 readl(altera_gc->regs + ALTERA_GPIO_IRQ_MASK)))) {
                writel(status, altera_gc->regs + ALTERA_GPIO_EDGE_CAP);
                for_each_set_bit(i, &status, gc->ngpio)
                        generic_handle_domain_irq(irqdomain, i);
        }

        chained_irq_exit(chip, desc);
}

static void altera_gpio_irq_leveL_high_handler(struct irq_desc *desc)
{
        struct gpio_chip *gc = irq_desc_get_handler_data(desc);
        struct altera_gpio_chip *altera_gc = gpiochip_get_data(gc);
        struct irq_domain *irqdomain = gc->irq.domain;
        struct irq_chip *chip;
        unsigned long status;
        int i;

        chip = irq_desc_get_chip(desc);

        chained_irq_enter(chip, desc);

        status = readl(altera_gc->regs + ALTERA_GPIO_DATA);
        status &= readl(altera_gc->regs + ALTERA_GPIO_IRQ_MASK);

        for_each_set_bit(i, &status, gc->ngpio)
                generic_handle_domain_irq(irqdomain, i);

        chained_irq_exit(chip, desc);
}

static const struct irq_chip altera_gpio_irq_chip = {
        .name = "altera-gpio",
        .irq_mask = altera_gpio_irq_mask,
        .irq_unmask = altera_gpio_irq_unmask,
        .irq_set_type = altera_gpio_irq_set_type,
        .irq_startup  = altera_gpio_irq_startup,
        .irq_shutdown = altera_gpio_irq_mask,
        .flags = IRQCHIP_IMMUTABLE,
        GPIOCHIP_IRQ_RESOURCE_HELPERS,
};

static int altera_gpio_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        int reg, ret;
        struct altera_gpio_chip *altera_gc;
        struct gpio_irq_chip *girq;
        int mapped_irq;

        altera_gc = devm_kzalloc(&pdev->dev, sizeof(*altera_gc), GFP_KERNEL);
        if (!altera_gc)
                return -ENOMEM;

        raw_spin_lock_init(&altera_gc->gpio_lock);

        if (device_property_read_u32(dev, "altr,ngpio", &reg))
                /* By default assume maximum ngpio */
                altera_gc->gc.ngpio = ALTERA_GPIO_MAX_NGPIO;
        else
                altera_gc->gc.ngpio = reg;

        if (altera_gc->gc.ngpio > ALTERA_GPIO_MAX_NGPIO) {
                dev_warn(&pdev->dev,
                        "ngpio is greater than %d, defaulting to %d\n",
                        ALTERA_GPIO_MAX_NGPIO, ALTERA_GPIO_MAX_NGPIO);
                altera_gc->gc.ngpio = ALTERA_GPIO_MAX_NGPIO;
        }

        altera_gc->gc.direction_input   = altera_gpio_direction_input;
        altera_gc->gc.direction_output  = altera_gpio_direction_output;
        altera_gc->gc.get               = altera_gpio_get;
        altera_gc->gc.set               = altera_gpio_set;
        altera_gc->gc.owner             = THIS_MODULE;
        altera_gc->gc.parent            = &pdev->dev;
        altera_gc->gc.base              = -1;

        altera_gc->gc.label = devm_kasprintf(dev, GFP_KERNEL, "%pfw", dev_fwnode(dev));
        if (!altera_gc->gc.label)
                return -ENOMEM;

        altera_gc->regs = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(altera_gc->regs))
                return dev_err_probe(dev, PTR_ERR(altera_gc->regs), "failed to ioremap memory resource\n");

        mapped_irq = platform_get_irq_optional(pdev, 0);
        if (mapped_irq < 0)
                goto skip_irq;

        if (device_property_read_u32(dev, "altr,interrupt-type", &reg)) {
                dev_err(&pdev->dev,
                        "altr,interrupt-type value not set in device tree\n");
                return -EINVAL;
        }
        altera_gc->interrupt_trigger = reg;

        girq = &altera_gc->gc.irq;
        gpio_irq_chip_set_chip(girq, &altera_gpio_irq_chip);

        if (altera_gc->interrupt_trigger == IRQ_TYPE_LEVEL_HIGH)
                girq->parent_handler = altera_gpio_irq_leveL_high_handler;
        else
                girq->parent_handler = altera_gpio_irq_edge_handler;
        girq->num_parents = 1;
        girq->parents = devm_kcalloc(&pdev->dev, 1, sizeof(*girq->parents),
                                     GFP_KERNEL);
        if (!girq->parents)
                return -ENOMEM;
        girq->default_type = IRQ_TYPE_NONE;
        girq->handler = handle_bad_irq;
        girq->parents[0] = mapped_irq;

skip_irq:
        ret = devm_gpiochip_add_data(dev, &altera_gc->gc, altera_gc);
        if (ret) {
                dev_err(&pdev->dev, "Failed adding memory mapped gpiochip\n");
                return ret;
        }

        return 0;
}

static const struct of_device_id altera_gpio_of_match[] = {
        { .compatible = "altr,pio-1.0", },
        {},
};
MODULE_DEVICE_TABLE(of, altera_gpio_of_match);

static struct platform_driver altera_gpio_driver = {
        .driver = {
                .name   = "altera_gpio",
                .of_match_table = altera_gpio_of_match,
        },
        .probe          = altera_gpio_probe,
};

static int __init altera_gpio_init(void)
{
        return platform_driver_register(&altera_gpio_driver);
}
subsys_initcall(altera_gpio_init);

static void __exit altera_gpio_exit(void)
{
        platform_driver_unregister(&altera_gpio_driver);
}
module_exit(altera_gpio_exit);

MODULE_AUTHOR("Tien Hock Loh <thloh@altera.com>");
MODULE_DESCRIPTION("Altera GPIO driver");
MODULE_LICENSE("GPL");