/*
 * Toumaz Xenif TZ1090 GPIO handling.
 *
 * Copyright (C) 2008-2013 Imagination Technologies Ltd.
 *
 *  Based on ARM PXA code and others.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/bitops.h>
#include <linux/export.h>
#include <linux/gpio.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/irqdomain.h>
#include <linux/kernel.h>
#include <linux/of_irq.h>
#include <linux/pinctrl/consumer.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/syscore_ops.h>
#include <asm/global_lock.h>

/* Register offsets from bank base address */
#define REG_GPIO_DIR            0x00
#define REG_GPIO_IRQ_PLRT       0x20
#define REG_GPIO_IRQ_TYPE       0x30
#define REG_GPIO_IRQ_EN         0x40
#define REG_GPIO_IRQ_STS        0x50
#define REG_GPIO_BIT_EN         0x60
#define REG_GPIO_DIN            0x70
#define REG_GPIO_DOUT           0x80

/* REG_GPIO_IRQ_PLRT */
#define REG_GPIO_IRQ_PLRT_LOW   0
#define REG_GPIO_IRQ_PLRT_HIGH  1

/* REG_GPIO_IRQ_TYPE */
#define REG_GPIO_IRQ_TYPE_LEVEL 0
#define REG_GPIO_IRQ_TYPE_EDGE  1

/**
 * struct tz1090_gpio_bank - GPIO bank private data
 * @chip:       Generic GPIO chip for GPIO bank
 * @domain:     IRQ domain for GPIO bank (may be NULL)
 * @reg:        Base of registers, offset for this GPIO bank
 * @irq:        IRQ number for GPIO bank
 * @label:      Debug GPIO bank label, used for storage of chip->label
 *
 * This is the main private data for a GPIO bank. It encapsulates a gpio_chip,
 * and the callbacks for the gpio_chip can access the private data with the
 * to_bank() macro below.
 */
struct tz1090_gpio_bank {
        struct gpio_chip chip;
        struct irq_domain *domain;
        void __iomem *reg;
        int irq;
        char label[16];
};

/**
 * struct tz1090_gpio - Overall GPIO device private data
 * @dev:        Device (from platform device)
 * @reg:        Base of GPIO registers
 *
 * Represents the overall GPIO device. This structure is actually only
 * temporary, and used during init.
 */
struct tz1090_gpio {
        struct device *dev;
        void __iomem *reg;
};

/**
 * struct tz1090_gpio_bank_info - Temporary registration info for GPIO bank
 * @priv:       Overall GPIO device private data
 * @node:       Device tree node specific to this GPIO bank
 * @index:      Index of bank in range 0-2
 */
struct tz1090_gpio_bank_info {
        struct tz1090_gpio *priv;
        struct device_node *node;
        unsigned int index;
};

/* Convenience register accessors */
static inline void tz1090_gpio_write(struct tz1090_gpio_bank *bank,
                              unsigned int reg_offs, u32 data)
{
        iowrite32(data, bank->reg + reg_offs);
}

static inline u32 tz1090_gpio_read(struct tz1090_gpio_bank *bank,
                            unsigned int reg_offs)
{
        return ioread32(bank->reg + reg_offs);
}

/* caller must hold LOCK2 */
static inline void _tz1090_gpio_clear_bit(struct tz1090_gpio_bank *bank,
                                          unsigned int reg_offs,
                                          unsigned int offset)
{
        u32 value;

        value = tz1090_gpio_read(bank, reg_offs);
        value &= ~BIT(offset);
        tz1090_gpio_write(bank, reg_offs, value);
}

static void tz1090_gpio_clear_bit(struct tz1090_gpio_bank *bank,
                                  unsigned int reg_offs,
                                  unsigned int offset)
{
        int lstat;

        __global_lock2(lstat);
        _tz1090_gpio_clear_bit(bank, reg_offs, offset);
        __global_unlock2(lstat);
}

/* caller must hold LOCK2 */
static inline void _tz1090_gpio_set_bit(struct tz1090_gpio_bank *bank,
                                        unsigned int reg_offs,
                                        unsigned int offset)
{
        u32 value;

        value = tz1090_gpio_read(bank, reg_offs);
        value |= BIT(offset);
        tz1090_gpio_write(bank, reg_offs, value);
}

static void tz1090_gpio_set_bit(struct tz1090_gpio_bank *bank,
                                unsigned int reg_offs,
                                unsigned int offset)
{
        int lstat;

        __global_lock2(lstat);
        _tz1090_gpio_set_bit(bank, reg_offs, offset);
        __global_unlock2(lstat);
}

/* caller must hold LOCK2 */
static inline void _tz1090_gpio_mod_bit(struct tz1090_gpio_bank *bank,
                                        unsigned int reg_offs,
                                        unsigned int offset,
                                        bool val)
{
        u32 value;

        value = tz1090_gpio_read(bank, reg_offs);
        value &= ~BIT(offset);
        if (val)
                value |= BIT(offset);
        tz1090_gpio_write(bank, reg_offs, value);
}

static void tz1090_gpio_mod_bit(struct tz1090_gpio_bank *bank,
                                unsigned int reg_offs,
                                unsigned int offset,
                                bool val)
{
        int lstat;

        __global_lock2(lstat);
        _tz1090_gpio_mod_bit(bank, reg_offs, offset, val);
        __global_unlock2(lstat);
}

static inline int tz1090_gpio_read_bit(struct tz1090_gpio_bank *bank,
                                       unsigned int reg_offs,
                                       unsigned int offset)
{
        return tz1090_gpio_read(bank, reg_offs) & BIT(offset);
}

/* GPIO chip callbacks */

static int tz1090_gpio_direction_input(struct gpio_chip *chip,
                                       unsigned int offset)
{
        struct tz1090_gpio_bank *bank = gpiochip_get_data(chip);
        tz1090_gpio_set_bit(bank, REG_GPIO_DIR, offset);

        return 0;
}

static int tz1090_gpio_direction_output(struct gpio_chip *chip,
                                        unsigned int offset, int output_value)
{
        struct tz1090_gpio_bank *bank = gpiochip_get_data(chip);
        int lstat;

        __global_lock2(lstat);
        _tz1090_gpio_mod_bit(bank, REG_GPIO_DOUT, offset, output_value);
        _tz1090_gpio_clear_bit(bank, REG_GPIO_DIR, offset);
        __global_unlock2(lstat);

        return 0;
}

/*
 * Return GPIO level
 */
static int tz1090_gpio_get(struct gpio_chip *chip, unsigned int offset)
{
        struct tz1090_gpio_bank *bank = gpiochip_get_data(chip);

        return !!tz1090_gpio_read_bit(bank, REG_GPIO_DIN, offset);
}

/*
 * Set output GPIO level
 */
static void tz1090_gpio_set(struct gpio_chip *chip, unsigned int offset,
                            int output_value)
{
        struct tz1090_gpio_bank *bank = gpiochip_get_data(chip);

        tz1090_gpio_mod_bit(bank, REG_GPIO_DOUT, offset, output_value);
}

static int tz1090_gpio_request(struct gpio_chip *chip, unsigned int offset)
{
        struct tz1090_gpio_bank *bank = gpiochip_get_data(chip);
        int ret;

        ret = pinctrl_gpio_request(chip->base + offset);
        if (ret)
                return ret;

        tz1090_gpio_set_bit(bank, REG_GPIO_DIR, offset);
        tz1090_gpio_set_bit(bank, REG_GPIO_BIT_EN, offset);

        return 0;
}

static void tz1090_gpio_free(struct gpio_chip *chip, unsigned int offset)
{
        struct tz1090_gpio_bank *bank = gpiochip_get_data(chip);

        pinctrl_gpio_free(chip->base + offset);

        tz1090_gpio_clear_bit(bank, REG_GPIO_BIT_EN, offset);
}

static int tz1090_gpio_to_irq(struct gpio_chip *chip, unsigned int offset)
{
        struct tz1090_gpio_bank *bank = gpiochip_get_data(chip);

        if (!bank->domain)
                return -EINVAL;

        return irq_create_mapping(bank->domain, offset);
}

/* IRQ chip handlers */

/* Get TZ1090 GPIO chip from irq data provided to generic IRQ callbacks */
static inline struct tz1090_gpio_bank *irqd_to_gpio_bank(struct irq_data *data)
{
        return (struct tz1090_gpio_bank *)data->domain->host_data;
}

static void tz1090_gpio_irq_polarity(struct tz1090_gpio_bank *bank,
                                     unsigned int offset, unsigned int polarity)
{
        tz1090_gpio_mod_bit(bank, REG_GPIO_IRQ_PLRT, offset, polarity);
}

static void tz1090_gpio_irq_type(struct tz1090_gpio_bank *bank,
                                 unsigned int offset, unsigned int type)
{
        tz1090_gpio_mod_bit(bank, REG_GPIO_IRQ_TYPE, offset, type);
}

/* set polarity to trigger on next edge, whether rising or falling */
static void tz1090_gpio_irq_next_edge(struct tz1090_gpio_bank *bank,
                                      unsigned int offset)
{
        unsigned int value_p, value_i;
        int lstat;

        /*
         * Set the GPIO's interrupt polarity to the opposite of the current
         * input value so that the next edge triggers an interrupt.
         */
        __global_lock2(lstat);
        value_i = ~tz1090_gpio_read(bank, REG_GPIO_DIN);
        value_p = tz1090_gpio_read(bank, REG_GPIO_IRQ_PLRT);
        value_p &= ~BIT(offset);
        value_p |= value_i & BIT(offset);
        tz1090_gpio_write(bank, REG_GPIO_IRQ_PLRT, value_p);
        __global_unlock2(lstat);
}

static unsigned int gpio_startup_irq(struct irq_data *data)
{
        /*
         * This warning indicates that the type of the irq hasn't been set
         * before enabling the irq. This would normally be done by passing some
         * trigger flags to request_irq().
         */
        WARN(irqd_get_trigger_type(data) == IRQ_TYPE_NONE,
                "irq type not set before enabling gpio irq %d", data->irq);

        irq_gc_ack_clr_bit(data);
        irq_gc_mask_set_bit(data);
        return 0;
}

static int gpio_set_irq_type(struct irq_data *data, unsigned int flow_type)
{
        struct tz1090_gpio_bank *bank = irqd_to_gpio_bank(data);
        unsigned int type;
        unsigned int polarity;

        switch (flow_type) {
        case IRQ_TYPE_EDGE_BOTH:
                type = REG_GPIO_IRQ_TYPE_EDGE;
                polarity = REG_GPIO_IRQ_PLRT_LOW;
                break;
        case IRQ_TYPE_EDGE_RISING:
                type = REG_GPIO_IRQ_TYPE_EDGE;
                polarity = REG_GPIO_IRQ_PLRT_HIGH;
                break;
        case IRQ_TYPE_EDGE_FALLING:
                type = REG_GPIO_IRQ_TYPE_EDGE;
                polarity = REG_GPIO_IRQ_PLRT_LOW;
                break;
        case IRQ_TYPE_LEVEL_HIGH:
                type = REG_GPIO_IRQ_TYPE_LEVEL;
                polarity = REG_GPIO_IRQ_PLRT_HIGH;
                break;
        case IRQ_TYPE_LEVEL_LOW:
                type = REG_GPIO_IRQ_TYPE_LEVEL;
                polarity = REG_GPIO_IRQ_PLRT_LOW;
                break;
        default:
                return -EINVAL;
        }

        tz1090_gpio_irq_type(bank, data->hwirq, type);
        irq_setup_alt_chip(data, flow_type);

        if (flow_type == IRQ_TYPE_EDGE_BOTH)
                tz1090_gpio_irq_next_edge(bank, data->hwirq);
        else
                tz1090_gpio_irq_polarity(bank, data->hwirq, polarity);

        return 0;
}

#ifdef CONFIG_SUSPEND
static int gpio_set_irq_wake(struct irq_data *data, unsigned int on)
{
        struct tz1090_gpio_bank *bank = irqd_to_gpio_bank(data);

#ifdef CONFIG_PM_DEBUG
        pr_info("irq_wake irq%d state:%d\n", data->irq, on);
#endif

        /* wake on gpio block interrupt */
        return irq_set_irq_wake(bank->irq, on);
}
#else
#define gpio_set_irq_wake NULL
#endif

static void tz1090_gpio_irq_handler(struct irq_desc *desc)
{
        irq_hw_number_t hw;
        unsigned int irq_stat, irq_no;
        struct tz1090_gpio_bank *bank;
        struct irq_desc *child_desc;

        bank = (struct tz1090_gpio_bank *)irq_desc_get_handler_data(desc);
        irq_stat = tz1090_gpio_read(bank, REG_GPIO_DIR) &
                   tz1090_gpio_read(bank, REG_GPIO_IRQ_STS) &
                   tz1090_gpio_read(bank, REG_GPIO_IRQ_EN) &
                   0x3FFFFFFF; /* 30 bits only */

        for (hw = 0; irq_stat; irq_stat >>= 1, ++hw) {
                if (!(irq_stat & 1))
                        continue;

                irq_no = irq_linear_revmap(bank->domain, hw);
                child_desc = irq_to_desc(irq_no);

                /* Toggle edge for pin with both edges triggering enabled */
                if (irqd_get_trigger_type(&child_desc->irq_data)
                                == IRQ_TYPE_EDGE_BOTH)
                        tz1090_gpio_irq_next_edge(bank, hw);

                generic_handle_irq_desc(child_desc);
        }
}

static int tz1090_gpio_bank_probe(struct tz1090_gpio_bank_info *info)
{
        struct device_node *np = info->node;
        struct device *dev = info->priv->dev;
        struct tz1090_gpio_bank *bank;
        struct irq_chip_generic *gc;
        int err;

        bank = devm_kzalloc(dev, sizeof(*bank), GFP_KERNEL);
        if (!bank) {
                dev_err(dev, "unable to allocate driver data\n");
                return -ENOMEM;
        }

        /* Offset the main registers to the first register in this bank */
        bank->reg = info->priv->reg + info->index * 4;

        /* Set up GPIO chip */
        snprintf(bank->label, sizeof(bank->label), "tz1090-gpio-%u",
                 info->index);
        bank->chip.label                = bank->label;
        bank->chip.parent               = dev;
        bank->chip.direction_input      = tz1090_gpio_direction_input;
        bank->chip.direction_output     = tz1090_gpio_direction_output;
        bank->chip.get                  = tz1090_gpio_get;
        bank->chip.set                  = tz1090_gpio_set;
        bank->chip.free                 = tz1090_gpio_free;
        bank->chip.request              = tz1090_gpio_request;
        bank->chip.to_irq               = tz1090_gpio_to_irq;
        bank->chip.of_node              = np;

        /* GPIO numbering from 0 */
        bank->chip.base                 = info->index * 30;
        bank->chip.ngpio                = 30;

        /* Add the GPIO bank */
        gpiochip_add_data(&bank->chip, bank);

        /* Get the GPIO bank IRQ if provided */
        bank->irq = irq_of_parse_and_map(np, 0);

        /* The interrupt is optional (it may be used by another core on chip) */
        if (!bank->irq) {
                dev_info(dev, "IRQ not provided for bank %u, IRQs disabled\n",
                         info->index);
                return 0;
        }

        dev_info(dev, "Setting up IRQs for GPIO bank %u\n",
                 info->index);

        /*
         * Initialise all interrupts to disabled so we don't get
         * spurious ones on a dirty boot and hit the BUG_ON in the
         * handler.
         */
        tz1090_gpio_write(bank, REG_GPIO_IRQ_EN, 0);

        /* Add a virtual IRQ for each GPIO */
        bank->domain = irq_domain_add_linear(np,
                                             bank->chip.ngpio,
                                             &irq_generic_chip_ops,
                                             bank);

        /* Set up a generic irq chip with 2 chip types (level and edge) */
        err = irq_alloc_domain_generic_chips(bank->domain, bank->chip.ngpio, 2,
                                             bank->label, handle_bad_irq, 0, 0,
                                             IRQ_GC_INIT_NESTED_LOCK);
        if (err) {
                dev_info(dev,
                         "irq_alloc_domain_generic_chips failed for bank %u, IRQs disabled\n",
                         info->index);
                irq_domain_remove(bank->domain);
                return 0;
        }

        gc = irq_get_domain_generic_chip(bank->domain, 0);
        gc->reg_base    = bank->reg;

        /* level chip type */
        gc->chip_types[0].type                  = IRQ_TYPE_LEVEL_MASK;
        gc->chip_types[0].handler               = handle_level_irq;
        gc->chip_types[0].regs.ack              = REG_GPIO_IRQ_STS;
        gc->chip_types[0].regs.mask             = REG_GPIO_IRQ_EN;
        gc->chip_types[0].chip.irq_startup      = gpio_startup_irq;
        gc->chip_types[0].chip.irq_ack          = irq_gc_ack_clr_bit;
        gc->chip_types[0].chip.irq_mask         = irq_gc_mask_clr_bit;
        gc->chip_types[0].chip.irq_unmask       = irq_gc_mask_set_bit;
        gc->chip_types[0].chip.irq_set_type     = gpio_set_irq_type;
        gc->chip_types[0].chip.irq_set_wake     = gpio_set_irq_wake;
        gc->chip_types[0].chip.flags            = IRQCHIP_MASK_ON_SUSPEND;

        /* edge chip type */
        gc->chip_types[1].type                  = IRQ_TYPE_EDGE_BOTH;
        gc->chip_types[1].handler               = handle_edge_irq;
        gc->chip_types[1].regs.ack              = REG_GPIO_IRQ_STS;
        gc->chip_types[1].regs.mask             = REG_GPIO_IRQ_EN;
        gc->chip_types[1].chip.irq_startup      = gpio_startup_irq;
        gc->chip_types[1].chip.irq_ack          = irq_gc_ack_clr_bit;
        gc->chip_types[1].chip.irq_mask         = irq_gc_mask_clr_bit;
        gc->chip_types[1].chip.irq_unmask       = irq_gc_mask_set_bit;
        gc->chip_types[1].chip.irq_set_type     = gpio_set_irq_type;
        gc->chip_types[1].chip.irq_set_wake     = gpio_set_irq_wake;
        gc->chip_types[1].chip.flags            = IRQCHIP_MASK_ON_SUSPEND;

        /* Setup chained handler for this GPIO bank */
        irq_set_chained_handler_and_data(bank->irq, tz1090_gpio_irq_handler,
                                         bank);

        return 0;
}

static void tz1090_gpio_register_banks(struct tz1090_gpio *priv)
{
        struct device_node *np = priv->dev->of_node;
        struct device_node *node;

        for_each_available_child_of_node(np, node) {
                struct tz1090_gpio_bank_info info;
                u32 addr;
                int ret;

                ret = of_property_read_u32(node, "reg", &addr);
                if (ret) {
                        dev_err(priv->dev, "invalid reg on %pOF\n", node);
                        continue;
                }
                if (addr >= 3) {
                        dev_err(priv->dev, "index %u in %pOF out of range\n",
                                addr, node);
                        continue;
                }

                info.index = addr;
                info.node = of_node_get(node);
                info.priv = priv;

                ret = tz1090_gpio_bank_probe(&info);
                if (ret) {
                        dev_err(priv->dev, "failure registering %pOF\n", node);
                        of_node_put(node);
                        continue;
                }
        }
}

static int tz1090_gpio_probe(struct platform_device *pdev)
{
        struct device_node *np = pdev->dev.of_node;
        struct resource *res_regs;
        struct tz1090_gpio priv;

        if (!np) {
                dev_err(&pdev->dev, "must be instantiated via devicetree\n");
                return -ENOENT;
        }

        res_regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res_regs) {
                dev_err(&pdev->dev, "cannot find registers resource\n");
                return -ENOENT;
        }

        priv.dev = &pdev->dev;

        /* Ioremap the registers */
        priv.reg = devm_ioremap(&pdev->dev, res_regs->start,
                                resource_size(res_regs));
        if (!priv.reg) {
                dev_err(&pdev->dev, "unable to ioremap registers\n");
                return -ENOMEM;
        }

        /* Look for banks */
        tz1090_gpio_register_banks(&priv);

        return 0;
}

static struct of_device_id tz1090_gpio_of_match[] = {
        { .compatible = "img,tz1090-gpio" },
        { },
};

static struct platform_driver tz1090_gpio_driver = {
        .driver = {
                .name           = "tz1090-gpio",
                .of_match_table = tz1090_gpio_of_match,
        },
        .probe          = tz1090_gpio_probe,
};

static int __init tz1090_gpio_init(void)
{
        return platform_driver_register(&tz1090_gpio_driver);
}
subsys_initcall(tz1090_gpio_init);