/*
 * 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_device.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/mfd/htc-egpio.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(unsigned int irq, struct irq_desc *desc)
{
        struct egpio_info *ei = get_irq_data(irq);
        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);
                irq = ei->irq_start + irqpin;
                desc = irq_to_desc(irq);
                desc->handle_irq(irq, desc);
        }
}

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

        /* Read current pins. */
        u16 readval = egpio_readw(ei, ei->ack_register);
        /* Ack/unmask interrupts. */
        ack_irqs(ei);
        /* Return first set pin. */
        readval &= ei->irqs_enabled;
        return ei->irq_start + ffs(readval) - 1;
}
EXPORT_SYMBOL(htc_egpio_get_wakeup_irq);

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

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


/*
 * Output pins
 */

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

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

        egpio = container_of(chip, struct egpio_chip, chip);
        ei    = dev_get_drvdata(egpio->dev);
        bit   = egpio_bit(ei, offset);
        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);
}

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

        egpio = container_of(chip, struct egpio_chip, chip);
        if (test_bit(offset, &egpio->is_out)) {
                egpio_set(chip, offset, value);
                return 0;
        } else {
                return -EINVAL;
        }
}

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 = pdev->dev.platform_data;
        struct resource   *res;
        struct egpio_info *ei;
        struct gpio_chip  *chip;
        unsigned int      irq, irq_end;
        int               i;
        int               ret;

        /* Initialize ei data structure. */
        ei = kzalloc(sizeof(*ei), GFP_KERNEL);
        if (!ei)
                return -ENOMEM;

        spin_lock_init(&ei->lock);

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

        /* Map egpio chip into virtual address space. */
        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res)
                goto fail;
        ei->base_addr = ioremap_nocache(res->start, resource_size(res));
        if (!ei->base_addr)
                goto fail;
        pr_debug("EGPIO phys=%08x virt=%p\n", (u32)res->start, ei->base_addr);

        if ((pdata->bus_width != 16) && (pdata->bus_width != 32))
                goto fail;
        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))
                goto fail;
        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 = kzalloc(sizeof(struct egpio_chip) * ei->nchips, GFP_KERNEL);
        if (!ei->chip) {
                ret = -ENOMEM;
                goto fail;
        }
        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           = "htc-egpio";
                chip->dev             = &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->base            = pdata->chip[i].gpio_base;
                chip->ngpio           = pdata->chip[i].num_gpios;

                gpiochip_add(chip);
        }

        /* 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++) {
                        set_irq_chip(irq, &egpio_muxed_chip);
                        set_irq_chip_data(irq, ei);
                        set_irq_handler(irq, handle_simple_irq);
                        set_irq_flags(irq, IRQF_VALID | IRQF_PROBE);
                }
                set_irq_type(ei->chained_irq, IRQ_TYPE_EDGE_RISING);
                set_irq_data(ei->chained_irq, ei);
                set_irq_chained_handler(ei->chained_irq, egpio_handler);
                ack_irqs(ei);

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

        return 0;

fail:
        printk(KERN_ERR "EGPIO failed to setup\n");
        kfree(ei);
        return ret;
}

static int __exit egpio_remove(struct platform_device *pdev)
{
        struct egpio_info *ei = platform_get_drvdata(pdev);
        unsigned int      irq, irq_end;

        if (ei->chained_irq) {
                irq_end = ei->irq_start + ei->nirqs;
                for (irq = ei->irq_start; irq < irq_end; irq++) {
                        set_irq_chip(irq, NULL);
                        set_irq_handler(irq, NULL);
                        set_irq_flags(irq, 0);
                }
                set_irq_chained_handler(ei->chained_irq, NULL);
                device_init_wakeup(&pdev->dev, 0);
        }
        iounmap(ei->base_addr);
        kfree(ei->chip);
        kfree(ei);

        return 0;
}

#ifdef CONFIG_PM
static int egpio_suspend(struct platform_device *pdev, pm_message_t state)
{
        struct egpio_info *ei = platform_get_drvdata(pdev);

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

static int egpio_resume(struct platform_device *pdev)
{
        struct egpio_info *ei = platform_get_drvdata(pdev);

        if (ei->chained_irq && device_may_wakeup(&pdev->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;
}
#else
#define egpio_suspend NULL
#define egpio_resume NULL
#endif


static struct platform_driver egpio_driver = {
        .driver = {
                .name = "htc-egpio",
        },
        .remove       = __exit_p(egpio_remove),
        .suspend      = egpio_suspend,
        .resume       = egpio_resume,
};

static int __init egpio_init(void)
{
        return platform_driver_probe(&egpio_driver, egpio_probe);
}

static void __exit egpio_exit(void)
{
        platform_driver_unregister(&egpio_driver);
}

/* start early for dependencies */
subsys_initcall(egpio_init);
module_exit(egpio_exit)

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Kevin O'Connor <kevin@koconnor.net>");