/*
 * TI DaVinci GPIO Support
 *
 * Copyright (c) 2006-2007 David Brownell
 * Copyright (c) 2007, MontaVista Software, Inc. <source@mvista.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */
#include <linux/gpio.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/irqdomain.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/platform_data/gpio-davinci.h>
#include <linux/irqchip/chained_irq.h>

struct davinci_gpio_regs {
        u32     dir;
        u32     out_data;
        u32     set_data;
        u32     clr_data;
        u32     in_data;
        u32     set_rising;
        u32     clr_rising;
        u32     set_falling;
        u32     clr_falling;
        u32     intstat;
};

typedef struct irq_chip *(*gpio_get_irq_chip_cb_t)(unsigned int irq);

#define BINTEN  0x8 /* GPIO Interrupt Per-Bank Enable Register */

#define chip2controller(chip)   \
        container_of(chip, struct davinci_gpio_controller, chip)

static void __iomem *gpio_base;

static struct davinci_gpio_regs __iomem *gpio2regs(unsigned gpio)
{
        void __iomem *ptr;

        if (gpio < 32 * 1)
                ptr = gpio_base + 0x10;
        else if (gpio < 32 * 2)
                ptr = gpio_base + 0x38;
        else if (gpio < 32 * 3)
                ptr = gpio_base + 0x60;
        else if (gpio < 32 * 4)
                ptr = gpio_base + 0x88;
        else if (gpio < 32 * 5)
                ptr = gpio_base + 0xb0;
        else
                ptr = NULL;
        return ptr;
}

static inline struct davinci_gpio_regs __iomem *irq2regs(int irq)
{
        struct davinci_gpio_regs __iomem *g;

        g = (__force struct davinci_gpio_regs __iomem *)irq_get_chip_data(irq);

        return g;
}

static int davinci_gpio_irq_setup(struct platform_device *pdev);

/*--------------------------------------------------------------------------*/

/* board setup code *MUST* setup pinmux and enable the GPIO clock. */
static inline int __davinci_direction(struct gpio_chip *chip,
                        unsigned offset, bool out, int value)
{
        struct davinci_gpio_controller *d = chip2controller(chip);
        struct davinci_gpio_regs __iomem *g = d->regs;
        unsigned long flags;
        u32 temp;
        u32 mask = 1 << offset;

        spin_lock_irqsave(&d->lock, flags);
        temp = readl_relaxed(&g->dir);
        if (out) {
                temp &= ~mask;
                writel_relaxed(mask, value ? &g->set_data : &g->clr_data);
        } else {
                temp |= mask;
        }
        writel_relaxed(temp, &g->dir);
        spin_unlock_irqrestore(&d->lock, flags);

        return 0;
}

static int davinci_direction_in(struct gpio_chip *chip, unsigned offset)
{
        return __davinci_direction(chip, offset, false, 0);
}

static int
davinci_direction_out(struct gpio_chip *chip, unsigned offset, int value)
{
        return __davinci_direction(chip, offset, true, value);
}

/*
 * Read the pin's value (works even if it's set up as output);
 * returns zero/nonzero.
 *
 * Note that changes are synched to the GPIO clock, so reading values back
 * right after you've set them may give old values.
 */
static int davinci_gpio_get(struct gpio_chip *chip, unsigned offset)
{
        struct davinci_gpio_controller *d = chip2controller(chip);
        struct davinci_gpio_regs __iomem *g = d->regs;

        return (1 << offset) & readl_relaxed(&g->in_data);
}

/*
 * Assuming the pin is muxed as a gpio output, set its output value.
 */
static void
davinci_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
{
        struct davinci_gpio_controller *d = chip2controller(chip);
        struct davinci_gpio_regs __iomem *g = d->regs;

        writel_relaxed((1 << offset), value ? &g->set_data : &g->clr_data);
}

static struct davinci_gpio_platform_data *
davinci_gpio_get_pdata(struct platform_device *pdev)
{
        struct device_node *dn = pdev->dev.of_node;
        struct davinci_gpio_platform_data *pdata;
        int ret;
        u32 val;

        if (!IS_ENABLED(CONFIG_OF) || !pdev->dev.of_node)
                return pdev->dev.platform_data;

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

        ret = of_property_read_u32(dn, "ti,ngpio", &val);
        if (ret)
                goto of_err;

        pdata->ngpio = val;

        ret = of_property_read_u32(dn, "ti,davinci-gpio-unbanked", &val);
        if (ret)
                goto of_err;

        pdata->gpio_unbanked = val;

        return pdata;

of_err:
        dev_err(&pdev->dev, "Populating pdata from DT failed: err %d\n", ret);
        return NULL;
}

#ifdef CONFIG_OF_GPIO
static int davinci_gpio_of_xlate(struct gpio_chip *gc,
                             const struct of_phandle_args *gpiospec,
                             u32 *flags)
{
        struct davinci_gpio_controller *chips = dev_get_drvdata(gc->dev);
        struct davinci_gpio_platform_data *pdata = dev_get_platdata(gc->dev);

        if (gpiospec->args[0] > pdata->ngpio)
                return -EINVAL;

        if (gc != &chips[gpiospec->args[0] / 32].chip)
                return -EINVAL;

        if (flags)
                *flags = gpiospec->args[1];

        return gpiospec->args[0] % 32;
}
#endif

static int davinci_gpio_probe(struct platform_device *pdev)
{
        int i, base;
        unsigned ngpio;
        struct davinci_gpio_controller *chips;
        struct davinci_gpio_platform_data *pdata;
        struct davinci_gpio_regs __iomem *regs;
        struct device *dev = &pdev->dev;
        struct resource *res;

        pdata = davinci_gpio_get_pdata(pdev);
        if (!pdata) {
                dev_err(dev, "No platform data found\n");
                return -EINVAL;
        }

        dev->platform_data = pdata;

        /*
         * The gpio banks conceptually expose a segmented bitmap,
         * and "ngpio" is one more than the largest zero-based
         * bit index that's valid.
         */
        ngpio = pdata->ngpio;
        if (ngpio == 0) {
                dev_err(dev, "How many GPIOs?\n");
                return -EINVAL;
        }

        if (WARN_ON(ARCH_NR_GPIOS < ngpio))
                ngpio = ARCH_NR_GPIOS;

        chips = devm_kzalloc(dev,
                             ngpio * sizeof(struct davinci_gpio_controller),
                             GFP_KERNEL);
        if (!chips)
                return -ENOMEM;

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res) {
                dev_err(dev, "Invalid memory resource\n");
                return -EBUSY;
        }

        gpio_base = devm_ioremap_resource(dev, res);
        if (IS_ERR(gpio_base))
                return PTR_ERR(gpio_base);

        for (i = 0, base = 0; base < ngpio; i++, base += 32) {
                chips[i].chip.label = "DaVinci";

                chips[i].chip.direction_input = davinci_direction_in;
                chips[i].chip.get = davinci_gpio_get;
                chips[i].chip.direction_output = davinci_direction_out;
                chips[i].chip.set = davinci_gpio_set;

                chips[i].chip.base = base;
                chips[i].chip.ngpio = ngpio - base;
                if (chips[i].chip.ngpio > 32)
                        chips[i].chip.ngpio = 32;

#ifdef CONFIG_OF_GPIO
                chips[i].chip.of_gpio_n_cells = 2;
                chips[i].chip.of_xlate = davinci_gpio_of_xlate;
                chips[i].chip.dev = dev;
                chips[i].chip.of_node = dev->of_node;
#endif
                spin_lock_init(&chips[i].lock);

                regs = gpio2regs(base);
                chips[i].regs = regs;
                chips[i].set_data = &regs->set_data;
                chips[i].clr_data = &regs->clr_data;
                chips[i].in_data = &regs->in_data;

                gpiochip_add(&chips[i].chip);
        }

        platform_set_drvdata(pdev, chips);
        davinci_gpio_irq_setup(pdev);
        return 0;
}

/*--------------------------------------------------------------------------*/
/*
 * We expect irqs will normally be set up as input pins, but they can also be
 * used as output pins ... which is convenient for testing.
 *
 * NOTE:  The first few GPIOs also have direct INTC hookups in addition
 * to their GPIOBNK0 irq, with a bit less overhead.
 *
 * All those INTC hookups (direct, plus several IRQ banks) can also
 * serve as EDMA event triggers.
 */

static void gpio_irq_disable(struct irq_data *d)
{
        struct davinci_gpio_regs __iomem *g = irq2regs(d->irq);
        u32 mask = (u32) irq_data_get_irq_handler_data(d);

        writel_relaxed(mask, &g->clr_falling);
        writel_relaxed(mask, &g->clr_rising);
}

static void gpio_irq_enable(struct irq_data *d)
{
        struct davinci_gpio_regs __iomem *g = irq2regs(d->irq);
        u32 mask = (u32) irq_data_get_irq_handler_data(d);
        unsigned status = irqd_get_trigger_type(d);

        status &= IRQ_TYPE_EDGE_FALLING | IRQ_TYPE_EDGE_RISING;
        if (!status)
                status = IRQ_TYPE_EDGE_FALLING | IRQ_TYPE_EDGE_RISING;

        if (status & IRQ_TYPE_EDGE_FALLING)
                writel_relaxed(mask, &g->set_falling);
        if (status & IRQ_TYPE_EDGE_RISING)
                writel_relaxed(mask, &g->set_rising);
}

static int gpio_irq_type(struct irq_data *d, unsigned trigger)
{
        if (trigger & ~(IRQ_TYPE_EDGE_FALLING | IRQ_TYPE_EDGE_RISING))
                return -EINVAL;

        return 0;
}

static struct irq_chip gpio_irqchip = {
        .name           = "GPIO",
        .irq_enable     = gpio_irq_enable,
        .irq_disable    = gpio_irq_disable,
        .irq_set_type   = gpio_irq_type,
        .flags          = IRQCHIP_SET_TYPE_MASKED,
};

static void
gpio_irq_handler(unsigned irq, struct irq_desc *desc)
{
        struct davinci_gpio_regs __iomem *g;
        u32 mask = 0xffff;
        struct davinci_gpio_controller *d;

        d = (struct davinci_gpio_controller *)irq_desc_get_handler_data(desc);
        g = (struct davinci_gpio_regs __iomem *)d->regs;

        /* we only care about one bank */
        if (irq & 1)
                mask <<= 16;

        /* temporarily mask (level sensitive) parent IRQ */
        chained_irq_enter(irq_desc_get_chip(desc), desc);
        while (1) {
                u32             status;
                int             bit;

                /* ack any irqs */
                status = readl_relaxed(&g->intstat) & mask;
                if (!status)
                        break;
                writel_relaxed(status, &g->intstat);

                /* now demux them to the right lowlevel handler */

                while (status) {
                        bit = __ffs(status);
                        status &= ~BIT(bit);
                        generic_handle_irq(
                                irq_find_mapping(d->irq_domain,
                                                 d->chip.base + bit));
                }
        }
        chained_irq_exit(irq_desc_get_chip(desc), desc);
        /* now it may re-trigger */
}

static int gpio_to_irq_banked(struct gpio_chip *chip, unsigned offset)
{
        struct davinci_gpio_controller *d = chip2controller(chip);

        if (d->irq_domain)
                return irq_create_mapping(d->irq_domain, d->chip.base + offset);
        else
                return -ENXIO;
}

static int gpio_to_irq_unbanked(struct gpio_chip *chip, unsigned offset)
{
        struct davinci_gpio_controller *d = chip2controller(chip);

        /*
         * NOTE:  we assume for now that only irqs in the first gpio_chip
         * can provide direct-mapped IRQs to AINTC (up to 32 GPIOs).
         */
        if (offset < d->gpio_unbanked)
                return d->gpio_irq + offset;
        else
                return -ENODEV;
}

static int gpio_irq_type_unbanked(struct irq_data *data, unsigned trigger)
{
        struct davinci_gpio_controller *d;
        struct davinci_gpio_regs __iomem *g;
        u32 mask;

        d = (struct davinci_gpio_controller *)data->handler_data;
        g = (struct davinci_gpio_regs __iomem *)d->regs;
        mask = __gpio_mask(data->irq - d->gpio_irq);

        if (trigger & ~(IRQ_TYPE_EDGE_FALLING | IRQ_TYPE_EDGE_RISING))
                return -EINVAL;

        writel_relaxed(mask, (trigger & IRQ_TYPE_EDGE_FALLING)
                     ? &g->set_falling : &g->clr_falling);
        writel_relaxed(mask, (trigger & IRQ_TYPE_EDGE_RISING)
                     ? &g->set_rising : &g->clr_rising);

        return 0;
}

static int
davinci_gpio_irq_map(struct irq_domain *d, unsigned int irq,
                     irq_hw_number_t hw)
{
        struct davinci_gpio_regs __iomem *g = gpio2regs(hw);

        irq_set_chip_and_handler_name(irq, &gpio_irqchip, handle_simple_irq,
                                "davinci_gpio");
        irq_set_irq_type(irq, IRQ_TYPE_NONE);
        irq_set_chip_data(irq, (__force void *)g);
        irq_set_handler_data(irq, (void *)__gpio_mask(hw));
        set_irq_flags(irq, IRQF_VALID);

        return 0;
}

static const struct irq_domain_ops davinci_gpio_irq_ops = {
        .map = davinci_gpio_irq_map,
        .xlate = irq_domain_xlate_onetwocell,
};

static struct irq_chip *davinci_gpio_get_irq_chip(unsigned int irq)
{
        static struct irq_chip_type gpio_unbanked;

        gpio_unbanked = *container_of(irq_get_chip(irq),
                                      struct irq_chip_type, chip);

        return &gpio_unbanked.chip;
};

static struct irq_chip *keystone_gpio_get_irq_chip(unsigned int irq)
{
        static struct irq_chip gpio_unbanked;

        gpio_unbanked = *irq_get_chip(irq);
        return &gpio_unbanked;
};

static const struct of_device_id davinci_gpio_ids[];

/*
 * NOTE:  for suspend/resume, probably best to make a platform_device with
 * suspend_late/resume_resume calls hooking into results of the set_wake()
 * calls ... so if no gpios are wakeup events the clock can be disabled,
 * with outputs left at previously set levels, and so that VDD3P3V.IOPWDN0
 * (dm6446) can be set appropriately for GPIOV33 pins.
 */

static int davinci_gpio_irq_setup(struct platform_device *pdev)
{
        unsigned        gpio, bank;
        int             irq;
        struct clk      *clk;
        u32             binten = 0;
        unsigned        ngpio, bank_irq;
        struct device *dev = &pdev->dev;
        struct resource *res;
        struct davinci_gpio_controller *chips = platform_get_drvdata(pdev);
        struct davinci_gpio_platform_data *pdata = dev->platform_data;
        struct davinci_gpio_regs __iomem *g;
        struct irq_domain       *irq_domain = NULL;
        const struct of_device_id *match;
        struct irq_chip *irq_chip;
        gpio_get_irq_chip_cb_t gpio_get_irq_chip;

        /*
         * Use davinci_gpio_get_irq_chip by default to handle non DT cases
         */
        gpio_get_irq_chip = davinci_gpio_get_irq_chip;
        match = of_match_device(of_match_ptr(davinci_gpio_ids),
                                dev);
        if (match)
                gpio_get_irq_chip = (gpio_get_irq_chip_cb_t)match->data;

        ngpio = pdata->ngpio;
        res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
        if (!res) {
                dev_err(dev, "Invalid IRQ resource\n");
                return -EBUSY;
        }

        bank_irq = res->start;

        if (!bank_irq) {
                dev_err(dev, "Invalid IRQ resource\n");
                return -ENODEV;
        }

        clk = devm_clk_get(dev, "gpio");
        if (IS_ERR(clk)) {
                printk(KERN_ERR "Error %ld getting gpio clock?\n",
                       PTR_ERR(clk));
                return PTR_ERR(clk);
        }
        clk_prepare_enable(clk);

        if (!pdata->gpio_unbanked) {
                irq = irq_alloc_descs(-1, 0, ngpio, 0);
                if (irq < 0) {
                        dev_err(dev, "Couldn't allocate IRQ numbers\n");
                        return irq;
                }

                irq_domain = irq_domain_add_legacy(NULL, ngpio, irq, 0,
                                                        &davinci_gpio_irq_ops,
                                                        chips);
                if (!irq_domain) {
                        dev_err(dev, "Couldn't register an IRQ domain\n");
                        return -ENODEV;
                }
        }

        /*
         * Arrange gpio_to_irq() support, handling either direct IRQs or
         * banked IRQs.  Having GPIOs in the first GPIO bank use direct
         * IRQs, while the others use banked IRQs, would need some setup
         * tweaks to recognize hardware which can do that.
         */
        for (gpio = 0, bank = 0; gpio < ngpio; bank++, gpio += 32) {
                chips[bank].chip.to_irq = gpio_to_irq_banked;
                chips[bank].irq_domain = irq_domain;
        }

        /*
         * AINTC can handle direct/unbanked IRQs for GPIOs, with the GPIO
         * controller only handling trigger modes.  We currently assume no
         * IRQ mux conflicts; gpio_irq_type_unbanked() is only for GPIOs.
         */
        if (pdata->gpio_unbanked) {
                /* pass "bank 0" GPIO IRQs to AINTC */
                chips[0].chip.to_irq = gpio_to_irq_unbanked;
                chips[0].gpio_irq = bank_irq;
                chips[0].gpio_unbanked = pdata->gpio_unbanked;
                binten = BIT(0);

                /* AINTC handles mask/unmask; GPIO handles triggering */
                irq = bank_irq;
                irq_chip = gpio_get_irq_chip(irq);
                irq_chip->name = "GPIO-AINTC";
                irq_chip->irq_set_type = gpio_irq_type_unbanked;

                /* default trigger: both edges */
                g = gpio2regs(0);
                writel_relaxed(~0, &g->set_falling);
                writel_relaxed(~0, &g->set_rising);

                /* set the direct IRQs up to use that irqchip */
                for (gpio = 0; gpio < pdata->gpio_unbanked; gpio++, irq++) {
                        irq_set_chip(irq, irq_chip);
                        irq_set_handler_data(irq, &chips[gpio / 32]);
                        irq_set_status_flags(irq, IRQ_TYPE_EDGE_BOTH);
                }

                goto done;
        }

        /*
         * Or, AINTC can handle IRQs for banks of 16 GPIO IRQs, which we
         * then chain through our own handler.
         */
        for (gpio = 0, bank = 0; gpio < ngpio; bank++, bank_irq++, gpio += 16) {
                /* disabled by default, enabled only as needed */
                g = gpio2regs(gpio);
                writel_relaxed(~0, &g->clr_falling);
                writel_relaxed(~0, &g->clr_rising);

                /* set up all irqs in this bank */
                irq_set_chained_handler(bank_irq, gpio_irq_handler);

                /*
                 * Each chip handles 32 gpios, and each irq bank consists of 16
                 * gpio irqs. Pass the irq bank's corresponding controller to
                 * the chained irq handler.
                 */
                irq_set_handler_data(bank_irq, &chips[gpio / 32]);

                binten |= BIT(bank);
        }

done:
        /*
         * BINTEN -- per-bank interrupt enable. genirq would also let these
         * bits be set/cleared dynamically.
         */
        writel_relaxed(binten, gpio_base + BINTEN);

        return 0;
}

#if IS_ENABLED(CONFIG_OF)
static const struct of_device_id davinci_gpio_ids[] = {
        { .compatible = "ti,keystone-gpio", keystone_gpio_get_irq_chip},
        { .compatible = "ti,dm6441-gpio", davinci_gpio_get_irq_chip},
        { /* sentinel */ },
};
MODULE_DEVICE_TABLE(of, davinci_gpio_ids);
#endif

static struct platform_driver davinci_gpio_driver = {
        .probe          = davinci_gpio_probe,
        .driver         = {
                .name           = "davinci_gpio",
                .owner          = THIS_MODULE,
                .of_match_table = of_match_ptr(davinci_gpio_ids),
        },
};

/**
 * GPIO driver registration needs to be done before machine_init functions
 * access GPIO. Hence davinci_gpio_drv_reg() is a postcore_initcall.
 */
static int __init davinci_gpio_drv_reg(void)
{
        return platform_driver_register(&davinci_gpio_driver);
}
postcore_initcall(davinci_gpio_drv_reg);