/*
 * Support for the GPIO/IRQ expander chips present on several HTC phones.
 * These are implemented in CPLD chips present on the board.
 *
 * Copyright (c) 2007 Kevin O'Connor <kevin@koconnor.net>
 * Copyright (c) 2007 Philipp Zabel <philipp.zabel@gmail.com>
 *
 * This file may be distributed under the terms of the GNU GPL license.
 */

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/io.h>
#include <linux/spinlock.h>
#include <linux/platform_data/gpio-htc-egpio.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/gpio/driver.h>

struct egpio_chip {
        int              reg_start;
        int              cached_values;
        unsigned long    is_out;
        struct device    *dev;
        struct gpio_chip chip;
};

struct egpio_info {
        spinlock_t        lock;

        /* iomem info */
        void __iomem      *base_addr;
        int               bus_shift;    /* byte shift */
        int               reg_shift;    /* bit shift */
        int               reg_mask;

        /* irq info */
        int               ack_register;
        int               ack_write;
        u16               irqs_enabled;
        uint              irq_start;
        int               nirqs;
        uint              chained_irq;

        /* egpio info */
        struct egpio_chip *chip;
        int               nchips;
};

static inline void egpio_writew(u16 value, struct egpio_info *ei, int reg)
{
        writew(value, ei->base_addr + (reg << ei->bus_shift));
}

static inline u16 egpio_readw(struct egpio_info *ei, int reg)
{
        return readw(ei->base_addr + (reg << ei->bus_shift));
}

/*
 * IRQs
 */

static inline void ack_irqs(struct egpio_info *ei)
{
        egpio_writew(ei->ack_write, ei, ei->ack_register);
        pr_debug("EGPIO ack - write %x to base+%x\n",
                        ei->ack_write, ei->ack_register << ei->bus_shift);
}

static void egpio_ack(struct irq_data *data)
{
}

/* There does not appear to be a way to proactively mask interrupts
 * on the egpio chip itself.  So, we simply ignore interrupts that
 * aren't desired. */
static void egpio_mask(struct irq_data *data)
{
        struct egpio_info *ei = irq_data_get_irq_chip_data(data);
        ei->irqs_enabled &= ~(1 << (data->irq - ei->irq_start));
        pr_debug("EGPIO mask %d %04x\n", data->irq, ei->irqs_enabled);
}

static void egpio_unmask(struct irq_data *data)
{
        struct egpio_info *ei = irq_data_get_irq_chip_data(data);
        ei->irqs_enabled |= 1 << (data->irq - ei->irq_start);
        pr_debug("EGPIO unmask %d %04x\n", data->irq, ei->irqs_enabled);
}

static struct irq_chip egpio_muxed_chip = {
        .name           = "htc-egpio",
        .irq_ack        = egpio_ack,
        .irq_mask       = egpio_mask,
        .irq_unmask     = egpio_unmask,
};

static void egpio_handler(struct irq_desc *desc)
{
        struct egpio_info *ei = irq_desc_get_handler_data(desc);
        int irqpin;

        /* Read current pins. */
        unsigned long readval = egpio_readw(ei, ei->ack_register);
        pr_debug("IRQ reg: %x\n", (unsigned int)readval);
        /* Ack/unmask interrupts. */
        ack_irqs(ei);
        /* Process all set pins. */
        readval &= ei->irqs_enabled;
        for_each_set_bit(irqpin, &readval, ei->nirqs) {
                /* Run irq handler */
                pr_debug("got IRQ %d\n", irqpin);
                generic_handle_irq(ei->irq_start + irqpin);
        }
}

static inline int egpio_pos(struct egpio_info *ei, int bit)
{
        return bit >> ei->reg_shift;
}

static inline int egpio_bit(struct egpio_info *ei, int bit)
{
        return 1 << (bit & ((1 << ei->reg_shift)-1));
}

/*
 * Input pins
 */

static int egpio_get(struct gpio_chip *chip, unsigned offset)
{
        struct egpio_chip *egpio;
        struct egpio_info *ei;
        unsigned           bit;
        int                reg;
        int                value;

        pr_debug("egpio_get_value(%d)\n", chip->base + offset);

        egpio = gpiochip_get_data(chip);
        ei    = dev_get_drvdata(egpio->dev);
        bit   = egpio_bit(ei, offset);
        reg   = egpio->reg_start + egpio_pos(ei, offset);

        if (test_bit(offset, &egpio->is_out)) {
                return !!(egpio->cached_values & (1 << offset));
        } else {
                value = egpio_readw(ei, reg);
                pr_debug("readw(%p + %x) = %x\n",
                         ei->base_addr, reg << ei->bus_shift, value);
                return !!(value & bit);
        }
}

static int egpio_direction_input(struct gpio_chip *chip, unsigned offset)
{
        struct egpio_chip *egpio;

        egpio = gpiochip_get_data(chip);
        return test_bit(offset, &egpio->is_out) ? -EINVAL : 0;
}


/*
 * Output pins
 */

static int egpio_set(struct gpio_chip *chip, unsigned int offset, int value)
{
        unsigned long     flag;
        struct egpio_chip *egpio;
        struct egpio_info *ei;
        int               pos;
        int               reg;
        int               shift;

        pr_debug("egpio_set(%s, %d(%d), %d)\n",
                        chip->label, offset, offset+chip->base, value);

        egpio = gpiochip_get_data(chip);
        ei    = dev_get_drvdata(egpio->dev);
        pos   = egpio_pos(ei, offset);
        reg   = egpio->reg_start + pos;
        shift = pos << ei->reg_shift;

        pr_debug("egpio %s: reg %d = 0x%04x\n", value ? "set" : "clear",
                        reg, (egpio->cached_values >> shift) & ei->reg_mask);

        spin_lock_irqsave(&ei->lock, flag);
        if (value)
                egpio->cached_values |= (1 << offset);
        else
                egpio->cached_values &= ~(1 << offset);
        egpio_writew((egpio->cached_values >> shift) & ei->reg_mask, ei, reg);
        spin_unlock_irqrestore(&ei->lock, flag);

        return 0;
}

static int egpio_direction_output(struct gpio_chip *chip,
                                        unsigned offset, int value)
{
        struct egpio_chip *egpio;

        egpio = gpiochip_get_data(chip);
        if (test_bit(offset, &egpio->is_out))
                return egpio_set(chip, offset, value);

        return -EINVAL;
}

static int egpio_get_direction(struct gpio_chip *chip, unsigned offset)
{
        struct egpio_chip *egpio;

        egpio = gpiochip_get_data(chip);

        if (test_bit(offset, &egpio->is_out))
                return GPIO_LINE_DIRECTION_OUT;

        return GPIO_LINE_DIRECTION_IN;
}

static void egpio_write_cache(struct egpio_info *ei)
{
        int               i;
        struct egpio_chip *egpio;
        int               shift;

        for (i = 0; i < ei->nchips; i++) {
                egpio = &(ei->chip[i]);
                if (!egpio->is_out)
                        continue;

                for (shift = 0; shift < egpio->chip.ngpio;
                                shift += (1<<ei->reg_shift)) {

                        int reg = egpio->reg_start + egpio_pos(ei, shift);

                        if (!((egpio->is_out >> shift) & ei->reg_mask))
                                continue;

                        pr_debug("EGPIO: setting %x to %x, was %x\n", reg,
                                (egpio->cached_values >> shift) & ei->reg_mask,
                                egpio_readw(ei, reg));

                        egpio_writew((egpio->cached_values >> shift)
                                        & ei->reg_mask, ei, reg);
                }
        }
}


/*
 * Setup
 */

static int __init egpio_probe(struct platform_device *pdev)
{
        struct htc_egpio_platform_data *pdata = dev_get_platdata(&pdev->dev);
        struct resource   *res;
        struct egpio_info *ei;
        struct gpio_chip  *chip;
        unsigned int      irq, irq_end;
        int               i;

        /* Initialize ei data structure. */
        ei = devm_kzalloc(&pdev->dev, sizeof(*ei), GFP_KERNEL);
        if (!ei)
                return -ENOMEM;

        spin_lock_init(&ei->lock);

        /* Find chained irq */
        res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
        if (res)
                ei->chained_irq = res->start;

        /* Map egpio chip into virtual address space. */
        ei->base_addr = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(ei->base_addr))
                return PTR_ERR(ei->base_addr);

        if ((pdata->bus_width != 16) && (pdata->bus_width != 32))
                return -EINVAL;

        ei->bus_shift = fls(pdata->bus_width - 1) - 3;
        pr_debug("bus_shift = %d\n", ei->bus_shift);

        if ((pdata->reg_width != 8) && (pdata->reg_width != 16))
                return -EINVAL;

        ei->reg_shift = fls(pdata->reg_width - 1);
        pr_debug("reg_shift = %d\n", ei->reg_shift);

        ei->reg_mask = (1 << pdata->reg_width) - 1;

        platform_set_drvdata(pdev, ei);

        ei->nchips = pdata->num_chips;
        ei->chip = devm_kcalloc(&pdev->dev,
                                ei->nchips, sizeof(struct egpio_chip),
                                GFP_KERNEL);
        if (!ei->chip)
                return -ENOMEM;

        for (i = 0; i < ei->nchips; i++) {
                ei->chip[i].reg_start = pdata->chip[i].reg_start;
                ei->chip[i].cached_values = pdata->chip[i].initial_values;
                ei->chip[i].is_out = pdata->chip[i].direction;
                ei->chip[i].dev = &(pdev->dev);
                chip = &(ei->chip[i].chip);
                chip->label = devm_kasprintf(&pdev->dev, GFP_KERNEL,
                                             "htc-egpio-%d",
                                             i);
                if (!chip->label)
                        return -ENOMEM;

                chip->parent          = &pdev->dev;
                chip->owner           = THIS_MODULE;
                chip->get             = egpio_get;
                chip->set             = egpio_set;
                chip->direction_input = egpio_direction_input;
                chip->direction_output = egpio_direction_output;
                chip->get_direction   = egpio_get_direction;
                chip->base            = pdata->chip[i].gpio_base;
                chip->ngpio           = pdata->chip[i].num_gpios;

                gpiochip_add_data(chip, &ei->chip[i]);
        }

        /* Set initial pin values */
        egpio_write_cache(ei);

        ei->irq_start = pdata->irq_base;
        ei->nirqs = pdata->num_irqs;
        ei->ack_register = pdata->ack_register;

        if (ei->chained_irq) {
                /* Setup irq handlers */
                ei->ack_write = 0xFFFF;
                if (pdata->invert_acks)
                        ei->ack_write = 0;
                irq_end = ei->irq_start + ei->nirqs;
                for (irq = ei->irq_start; irq < irq_end; irq++) {
                        irq_set_chip_and_handler(irq, &egpio_muxed_chip,
                                                 handle_simple_irq);
                        irq_set_chip_data(irq, ei);
                        irq_clear_status_flags(irq, IRQ_NOREQUEST | IRQ_NOPROBE);
                }
                irq_set_irq_type(ei->chained_irq, IRQ_TYPE_EDGE_RISING);
                irq_set_chained_handler_and_data(ei->chained_irq,
                                                 egpio_handler, ei);
                ack_irqs(ei);

                device_init_wakeup(&pdev->dev, 1);
        }

        return 0;
}

static int egpio_suspend(struct device *dev)
{
        struct egpio_info *ei = dev_get_drvdata(dev);

        if (ei->chained_irq && device_may_wakeup(dev))
                enable_irq_wake(ei->chained_irq);
        return 0;
}

static int egpio_resume(struct device *dev)
{
        struct egpio_info *ei = dev_get_drvdata(dev);

        if (ei->chained_irq && device_may_wakeup(dev))
                disable_irq_wake(ei->chained_irq);

        /* Update registers from the cache, in case
           the CPLD was powered off during suspend */
        egpio_write_cache(ei);
        return 0;
}

static DEFINE_SIMPLE_DEV_PM_OPS(egpio_pm_ops, egpio_suspend, egpio_resume);

static struct platform_driver egpio_driver = {
        .driver = {
                .name = "htc-egpio",
                .suppress_bind_attrs = true,
                .pm = pm_sleep_ptr(&egpio_pm_ops),
        },
};

static int __init egpio_init(void)
{
        return platform_driver_probe(&egpio_driver, egpio_probe);
}
/* start early for dependencies */
subsys_initcall(egpio_init);