/*
 * Copyright (C) 2015 Broadcom Corporation
 *
 * 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 version 2.
 *
 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
 * kind, whether express or implied; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/bitops.h>
#include <linux/gpio/driver.h>
#include <linux/of_device.h>
#include <linux/of_irq.h>
#include <linux/module.h>
#include <linux/irqdomain.h>
#include <linux/irqchip/chained_irq.h>
#include <linux/interrupt.h>
#include <linux/reboot.h>

#define GIO_BANK_SIZE           0x20
#define GIO_ODEN(bank)          (((bank) * GIO_BANK_SIZE) + 0x00)
#define GIO_DATA(bank)          (((bank) * GIO_BANK_SIZE) + 0x04)
#define GIO_IODIR(bank)         (((bank) * GIO_BANK_SIZE) + 0x08)
#define GIO_EC(bank)            (((bank) * GIO_BANK_SIZE) + 0x0c)
#define GIO_EI(bank)            (((bank) * GIO_BANK_SIZE) + 0x10)
#define GIO_MASK(bank)          (((bank) * GIO_BANK_SIZE) + 0x14)
#define GIO_LEVEL(bank)         (((bank) * GIO_BANK_SIZE) + 0x18)
#define GIO_STAT(bank)          (((bank) * GIO_BANK_SIZE) + 0x1c)

struct brcmstb_gpio_bank {
        struct list_head node;
        int id;
        struct gpio_chip gc;
        struct brcmstb_gpio_priv *parent_priv;
        u32 width;
        struct irq_chip irq_chip;
};

struct brcmstb_gpio_priv {
        struct list_head bank_list;
        void __iomem *reg_base;
        struct platform_device *pdev;
        int parent_irq;
        int gpio_base;
        bool can_wake;
        int parent_wake_irq;
        struct notifier_block reboot_notifier;
};

#define MAX_GPIO_PER_BANK           32
#define GPIO_BANK(gpio)         ((gpio) >> 5)
/* assumes MAX_GPIO_PER_BANK is a multiple of 2 */
#define GPIO_BIT(gpio)          ((gpio) & (MAX_GPIO_PER_BANK - 1))

static inline struct brcmstb_gpio_priv *
brcmstb_gpio_gc_to_priv(struct gpio_chip *gc)
{
        struct brcmstb_gpio_bank *bank = gpiochip_get_data(gc);
        return bank->parent_priv;
}

static void brcmstb_gpio_set_imask(struct brcmstb_gpio_bank *bank,
                unsigned int offset, bool enable)
{
        struct gpio_chip *gc = &bank->gc;
        struct brcmstb_gpio_priv *priv = bank->parent_priv;
        u32 mask = gc->pin2mask(gc, offset);
        u32 imask;
        unsigned long flags;

        spin_lock_irqsave(&gc->bgpio_lock, flags);
        imask = gc->read_reg(priv->reg_base + GIO_MASK(bank->id));
        if (enable)
                imask |= mask;
        else
                imask &= ~mask;
        gc->write_reg(priv->reg_base + GIO_MASK(bank->id), imask);
        spin_unlock_irqrestore(&gc->bgpio_lock, flags);
}

/* -------------------- IRQ chip functions -------------------- */

static void brcmstb_gpio_irq_mask(struct irq_data *d)
{
        struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
        struct brcmstb_gpio_bank *bank = gpiochip_get_data(gc);

        brcmstb_gpio_set_imask(bank, d->hwirq, false);
}

static void brcmstb_gpio_irq_unmask(struct irq_data *d)
{
        struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
        struct brcmstb_gpio_bank *bank = gpiochip_get_data(gc);

        brcmstb_gpio_set_imask(bank, d->hwirq, true);
}

static int brcmstb_gpio_irq_set_type(struct irq_data *d, unsigned int type)
{
        struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
        struct brcmstb_gpio_bank *bank = gpiochip_get_data(gc);
        struct brcmstb_gpio_priv *priv = bank->parent_priv;
        u32 mask = BIT(d->hwirq);
        u32 edge_insensitive, iedge_insensitive;
        u32 edge_config, iedge_config;
        u32 level, ilevel;
        unsigned long flags;

        switch (type) {
        case IRQ_TYPE_LEVEL_LOW:
                level = 0;
                edge_config = 0;
                edge_insensitive = 0;
                break;
        case IRQ_TYPE_LEVEL_HIGH:
                level = mask;
                edge_config = 0;
                edge_insensitive = 0;
                break;
        case IRQ_TYPE_EDGE_FALLING:
                level = 0;
                edge_config = 0;
                edge_insensitive = 0;
                break;
        case IRQ_TYPE_EDGE_RISING:
                level = 0;
                edge_config = mask;
                edge_insensitive = 0;
                break;
        case IRQ_TYPE_EDGE_BOTH:
                level = 0;
                edge_config = 0;  /* don't care, but want known value */
                edge_insensitive = mask;
                break;
        default:
                return -EINVAL;
        }

        spin_lock_irqsave(&bank->gc.bgpio_lock, flags);

        iedge_config = bank->gc.read_reg(priv->reg_base +
                        GIO_EC(bank->id)) & ~mask;
        iedge_insensitive = bank->gc.read_reg(priv->reg_base +
                        GIO_EI(bank->id)) & ~mask;
        ilevel = bank->gc.read_reg(priv->reg_base +
                        GIO_LEVEL(bank->id)) & ~mask;

        bank->gc.write_reg(priv->reg_base + GIO_EC(bank->id),
                        iedge_config | edge_config);
        bank->gc.write_reg(priv->reg_base + GIO_EI(bank->id),
                        iedge_insensitive | edge_insensitive);
        bank->gc.write_reg(priv->reg_base + GIO_LEVEL(bank->id),
                        ilevel | level);

        spin_unlock_irqrestore(&bank->gc.bgpio_lock, flags);
        return 0;
}

static int brcmstb_gpio_priv_set_wake(struct brcmstb_gpio_priv *priv,
                unsigned int enable)
{
        int ret = 0;

        /*
         * Only enable wake IRQ once for however many hwirqs can wake
         * since they all use the same wake IRQ.  Mask will be set
         * up appropriately thanks to IRQCHIP_MASK_ON_SUSPEND flag.
         */
        if (enable)
                ret = enable_irq_wake(priv->parent_wake_irq);
        else
                ret = disable_irq_wake(priv->parent_wake_irq);
        if (ret)
                dev_err(&priv->pdev->dev, "failed to %s wake-up interrupt\n",
                                enable ? "enable" : "disable");
        return ret;
}

static int brcmstb_gpio_irq_set_wake(struct irq_data *d, unsigned int enable)
{
        struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
        struct brcmstb_gpio_priv *priv = brcmstb_gpio_gc_to_priv(gc);

        return brcmstb_gpio_priv_set_wake(priv, enable);
}

static irqreturn_t brcmstb_gpio_wake_irq_handler(int irq, void *data)
{
        struct brcmstb_gpio_priv *priv = data;

        if (!priv || irq != priv->parent_wake_irq)
                return IRQ_NONE;
        pm_wakeup_event(&priv->pdev->dev, 0);
        return IRQ_HANDLED;
}

static void brcmstb_gpio_irq_bank_handler(struct brcmstb_gpio_bank *bank)
{
        struct brcmstb_gpio_priv *priv = bank->parent_priv;
        struct irq_domain *irq_domain = bank->gc.irqdomain;
        void __iomem *reg_base = priv->reg_base;
        unsigned long status;
        unsigned long flags;

        spin_lock_irqsave(&bank->gc.bgpio_lock, flags);
        while ((status = bank->gc.read_reg(reg_base + GIO_STAT(bank->id)) &
                         bank->gc.read_reg(reg_base + GIO_MASK(bank->id)))) {
                int bit;

                for_each_set_bit(bit, &status, 32) {
                        u32 stat = bank->gc.read_reg(reg_base +
                                                      GIO_STAT(bank->id));
                        if (bit >= bank->width)
                                dev_warn(&priv->pdev->dev,
                                         "IRQ for invalid GPIO (bank=%d, offset=%d)\n",
                                         bank->id, bit);
                        bank->gc.write_reg(reg_base + GIO_STAT(bank->id),
                                            stat | BIT(bit));
                        generic_handle_irq(irq_find_mapping(irq_domain, bit));
                }
        }
        spin_unlock_irqrestore(&bank->gc.bgpio_lock, flags);
}

/* Each UPG GIO block has one IRQ for all banks */
static void brcmstb_gpio_irq_handler(struct irq_desc *desc)
{
        struct gpio_chip *gc = irq_desc_get_handler_data(desc);
        struct brcmstb_gpio_priv *priv = brcmstb_gpio_gc_to_priv(gc);
        struct irq_chip *chip = irq_desc_get_chip(desc);
        struct brcmstb_gpio_bank *bank;

        /* Interrupts weren't properly cleared during probe */
        BUG_ON(!priv || !chip);

        chained_irq_enter(chip, desc);
        list_for_each_entry(bank, &priv->bank_list, node)
                brcmstb_gpio_irq_bank_handler(bank);
        chained_irq_exit(chip, desc);
}

static int brcmstb_gpio_reboot(struct notifier_block *nb,
                unsigned long action, void *data)
{
        struct brcmstb_gpio_priv *priv =
                container_of(nb, struct brcmstb_gpio_priv, reboot_notifier);

        /* Enable GPIO for S5 cold boot */
        if (action == SYS_POWER_OFF)
                brcmstb_gpio_priv_set_wake(priv, 1);

        return NOTIFY_DONE;
}

/* Make sure that the number of banks matches up between properties */
static int brcmstb_gpio_sanity_check_banks(struct device *dev,
                struct device_node *np, struct resource *res)
{
        int res_num_banks = resource_size(res) / GIO_BANK_SIZE;
        int num_banks =
                of_property_count_u32_elems(np, "brcm,gpio-bank-widths");

        if (res_num_banks != num_banks) {
                dev_err(dev, "Mismatch in banks: res had %d, bank-widths had %d\n",
                                res_num_banks, num_banks);
                return -EINVAL;
        } else {
                return 0;
        }
}

static int brcmstb_gpio_remove(struct platform_device *pdev)
{
        struct brcmstb_gpio_priv *priv = platform_get_drvdata(pdev);
        struct brcmstb_gpio_bank *bank;
        int ret = 0;

        if (!priv) {
                dev_err(&pdev->dev, "called %s without drvdata!\n", __func__);
                return -EFAULT;
        }

        /*
         * You can lose return values below, but we report all errors, and it's
         * more important to actually perform all of the steps.
         */
        list_for_each_entry(bank, &priv->bank_list, node)
                gpiochip_remove(&bank->gc);

        if (priv->reboot_notifier.notifier_call) {
                ret = unregister_reboot_notifier(&priv->reboot_notifier);
                if (ret)
                        dev_err(&pdev->dev,
                                "failed to unregister reboot notifier\n");
        }
        return ret;
}

static int brcmstb_gpio_of_xlate(struct gpio_chip *gc,
                const struct of_phandle_args *gpiospec, u32 *flags)
{
        struct brcmstb_gpio_priv *priv = brcmstb_gpio_gc_to_priv(gc);
        struct brcmstb_gpio_bank *bank = gpiochip_get_data(gc);
        int offset;

        if (gc->of_gpio_n_cells != 2) {
                WARN_ON(1);
                return -EINVAL;
        }

        if (WARN_ON(gpiospec->args_count < gc->of_gpio_n_cells))
                return -EINVAL;

        offset = gpiospec->args[0] - (gc->base - priv->gpio_base);
        if (offset >= gc->ngpio || offset < 0)
                return -EINVAL;

        if (unlikely(offset >= bank->width)) {
                dev_warn_ratelimited(&priv->pdev->dev,
                        "Received request for invalid GPIO offset %d\n",
                        gpiospec->args[0]);
        }

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

        return offset;
}

/* Before calling, must have bank->parent_irq set and gpiochip registered */
static int brcmstb_gpio_irq_setup(struct platform_device *pdev,
                struct brcmstb_gpio_bank *bank)
{
        struct brcmstb_gpio_priv *priv = bank->parent_priv;
        struct device *dev = &pdev->dev;
        struct device_node *np = dev->of_node;

        bank->irq_chip.name = dev_name(dev);
        bank->irq_chip.irq_mask = brcmstb_gpio_irq_mask;
        bank->irq_chip.irq_unmask = brcmstb_gpio_irq_unmask;
        bank->irq_chip.irq_set_type = brcmstb_gpio_irq_set_type;

        /* Ensures that all non-wakeup IRQs are disabled at suspend */
        bank->irq_chip.flags = IRQCHIP_MASK_ON_SUSPEND;

        if (IS_ENABLED(CONFIG_PM_SLEEP) && !priv->can_wake &&
                        of_property_read_bool(np, "wakeup-source")) {
                priv->parent_wake_irq = platform_get_irq(pdev, 1);
                if (priv->parent_wake_irq < 0) {
                        dev_warn(dev,
                                "Couldn't get wake IRQ - GPIOs will not be able to wake from sleep");
                } else {
                        int err;

                        /*
                         * Set wakeup capability before requesting wakeup
                         * interrupt, so we can process boot-time "wakeups"
                         * (e.g., from S5 cold boot)
                         */
                        device_set_wakeup_capable(dev, true);
                        device_wakeup_enable(dev);
                        err = devm_request_irq(dev, priv->parent_wake_irq,
                                        brcmstb_gpio_wake_irq_handler, 0,
                                        "brcmstb-gpio-wake", priv);

                        if (err < 0) {
                                dev_err(dev, "Couldn't request wake IRQ");
                                return err;
                        }

                        priv->reboot_notifier.notifier_call =
                                brcmstb_gpio_reboot;
                        register_reboot_notifier(&priv->reboot_notifier);
                        priv->can_wake = true;
                }
        }

        if (priv->can_wake)
                bank->irq_chip.irq_set_wake = brcmstb_gpio_irq_set_wake;

        gpiochip_irqchip_add(&bank->gc, &bank->irq_chip, 0,
                        handle_simple_irq, IRQ_TYPE_NONE);
        gpiochip_set_chained_irqchip(&bank->gc, &bank->irq_chip,
                        priv->parent_irq, brcmstb_gpio_irq_handler);

        return 0;
}

static int brcmstb_gpio_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct device_node *np = dev->of_node;
        void __iomem *reg_base;
        struct brcmstb_gpio_priv *priv;
        struct resource *res;
        struct property *prop;
        const __be32 *p;
        u32 bank_width;
        int num_banks = 0;
        int err;
        static int gpio_base;
        unsigned long flags = 0;

        priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
        if (!priv)
                return -ENOMEM;
        platform_set_drvdata(pdev, priv);
        INIT_LIST_HEAD(&priv->bank_list);

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        reg_base = devm_ioremap_resource(dev, res);
        if (IS_ERR(reg_base))
                return PTR_ERR(reg_base);

        priv->gpio_base = gpio_base;
        priv->reg_base = reg_base;
        priv->pdev = pdev;

        if (of_property_read_bool(np, "interrupt-controller")) {
                priv->parent_irq = platform_get_irq(pdev, 0);
                if (priv->parent_irq <= 0) {
                        dev_err(dev, "Couldn't get IRQ");
                        return -ENOENT;
                }
        } else {
                priv->parent_irq = -ENOENT;
        }

        if (brcmstb_gpio_sanity_check_banks(dev, np, res))
                return -EINVAL;

        /*
         * MIPS endianness is configured by boot strap, which also reverses all
         * bus endianness (i.e., big-endian CPU + big endian bus ==> native
         * endian I/O).
         *
         * Other architectures (e.g., ARM) either do not support big endian, or
         * else leave I/O in little endian mode.
         */
#if defined(CONFIG_MIPS) && defined(__BIG_ENDIAN)
        flags = BGPIOF_BIG_ENDIAN_BYTE_ORDER;
#endif

        of_property_for_each_u32(np, "brcm,gpio-bank-widths", prop, p,
                        bank_width) {
                struct brcmstb_gpio_bank *bank;
                struct gpio_chip *gc;

                bank = devm_kzalloc(dev, sizeof(*bank), GFP_KERNEL);
                if (!bank) {
                        err = -ENOMEM;
                        goto fail;
                }

                bank->parent_priv = priv;
                bank->id = num_banks;
                if (bank_width <= 0 || bank_width > MAX_GPIO_PER_BANK) {
                        dev_err(dev, "Invalid bank width %d\n", bank_width);
                        err = -EINVAL;
                        goto fail;
                } else {
                        bank->width = bank_width;
                }

                /*
                 * Regs are 4 bytes wide, have data reg, no set/clear regs,
                 * and direction bits have 0 = output and 1 = input
                 */
                gc = &bank->gc;
                err = bgpio_init(gc, dev, 4,
                                reg_base + GIO_DATA(bank->id),
                                NULL, NULL, NULL,
                                reg_base + GIO_IODIR(bank->id), flags);
                if (err) {
                        dev_err(dev, "bgpio_init() failed\n");
                        goto fail;
                }

                gc->of_node = np;
                gc->owner = THIS_MODULE;
                gc->label = np->full_name;
                gc->base = gpio_base;
                gc->of_gpio_n_cells = 2;
                gc->of_xlate = brcmstb_gpio_of_xlate;
                /* not all ngpio lines are valid, will use bank width later */
                gc->ngpio = MAX_GPIO_PER_BANK;

                /*
                 * Mask all interrupts by default, since wakeup interrupts may
                 * be retained from S5 cold boot
                 */
                gc->write_reg(reg_base + GIO_MASK(bank->id), 0);

                err = gpiochip_add_data(gc, bank);
                if (err) {
                        dev_err(dev, "Could not add gpiochip for bank %d\n",
                                        bank->id);
                        goto fail;
                }
                gpio_base += gc->ngpio;

                if (priv->parent_irq > 0) {
                        err = brcmstb_gpio_irq_setup(pdev, bank);
                        if (err)
                                goto fail;
                }

                dev_dbg(dev, "bank=%d, base=%d, ngpio=%d, width=%d\n", bank->id,
                        gc->base, gc->ngpio, bank->width);

                /* Everything looks good, so add bank to list */
                list_add(&bank->node, &priv->bank_list);

                num_banks++;
        }

        dev_info(dev, "Registered %d banks (GPIO(s): %d-%d)\n",
                        num_banks, priv->gpio_base, gpio_base - 1);

        return 0;

fail:
        (void) brcmstb_gpio_remove(pdev);
        return err;
}

static const struct of_device_id brcmstb_gpio_of_match[] = {
        { .compatible = "brcm,brcmstb-gpio" },
        {},
};

MODULE_DEVICE_TABLE(of, brcmstb_gpio_of_match);

static struct platform_driver brcmstb_gpio_driver = {
        .driver = {
                .name = "brcmstb-gpio",
                .of_match_table = brcmstb_gpio_of_match,
        },
        .probe = brcmstb_gpio_probe,
        .remove = brcmstb_gpio_remove,
};
module_platform_driver(brcmstb_gpio_driver);

MODULE_AUTHOR("Gregory Fong");
MODULE_DESCRIPTION("Driver for Broadcom BRCMSTB SoC UPG GPIO");
MODULE_LICENSE("GPL v2");