/*
 * Pinctrl GPIO driver for Intel Baytrail
 * Copyright (c) 2012-2013, Intel Corporation.
 *
 * Author: Mathias Nyman <mathias.nyman@linux.intel.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 *
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/bitops.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/gpio.h>
#include <linux/irqdomain.h>
#include <linux/acpi.h>
#include <linux/acpi_gpio.h>
#include <linux/platform_device.h>
#include <linux/seq_file.h>
#include <linux/io.h>
#include <linux/pm_runtime.h>
#include <linux/pinctrl/pinctrl.h>

/* memory mapped register offsets */
#define BYT_CONF0_REG           0x000
#define BYT_CONF1_REG           0x004
#define BYT_VAL_REG             0x008
#define BYT_DFT_REG             0x00c
#define BYT_INT_STAT_REG        0x800

/* BYT_CONF0_REG register bits */
#define BYT_TRIG_NEG            BIT(26)
#define BYT_TRIG_POS            BIT(25)
#define BYT_TRIG_LVL            BIT(24)
#define BYT_PIN_MUX             0x07

/* BYT_VAL_REG register bits */
#define BYT_INPUT_EN            BIT(2)  /* 0: input enabled (active low)*/
#define BYT_OUTPUT_EN           BIT(1)  /* 0: output enabled (active low)*/
#define BYT_LEVEL               BIT(0)

#define BYT_DIR_MASK            (BIT(1) | BIT(2))
#define BYT_TRIG_MASK           (BIT(26) | BIT(25) | BIT(24))

#define BYT_NGPIO_SCORE         102
#define BYT_NGPIO_NCORE         28
#define BYT_NGPIO_SUS           44

/*
 * Baytrail gpio controller consist of three separate sub-controllers called
 * SCORE, NCORE and SUS. The sub-controllers are identified by their acpi UID.
 *
 * GPIO numbering is _not_ ordered meaning that gpio # 0 in ACPI namespace does
 * _not_ correspond to the first gpio register at controller's gpio base.
 * There is no logic or pattern in mapping gpio numbers to registers (pads) so
 * each sub-controller needs to have its own mapping table
 */

/* score_pins[gpio_nr] = pad_nr */

static unsigned const score_pins[BYT_NGPIO_SCORE] = {
        85, 89, 93, 96, 99, 102, 98, 101, 34, 37,
        36, 38, 39, 35, 40, 84, 62, 61, 64, 59,
        54, 56, 60, 55, 63, 57, 51, 50, 53, 47,
        52, 49, 48, 43, 46, 41, 45, 42, 58, 44,
        95, 105, 70, 68, 67, 66, 69, 71, 65, 72,
        86, 90, 88, 92, 103, 77, 79, 83, 78, 81,
        80, 82, 13, 12, 15, 14, 17, 18, 19, 16,
        2, 1, 0, 4, 6, 7, 9, 8, 33, 32,
        31, 30, 29, 27, 25, 28, 26, 23, 21, 20,
        24, 22, 5, 3, 10, 11, 106, 87, 91, 104,
        97, 100,
};

static unsigned const ncore_pins[BYT_NGPIO_NCORE] = {
        19, 18, 17, 20, 21, 22, 24, 25, 23, 16,
        14, 15, 12, 26, 27, 1, 4, 8, 11, 0,
        3, 6, 10, 13, 2, 5, 9, 7,
};

static unsigned const sus_pins[BYT_NGPIO_SUS] = {
        29, 33, 30, 31, 32, 34, 36, 35, 38, 37,
        18, 7, 11, 20, 17, 1, 8, 10, 19, 12,
        0, 2, 23, 39, 28, 27, 22, 21, 24, 25,
        26, 51, 56, 54, 49, 55, 48, 57, 50, 58,
        52, 53, 59, 40,
};

static struct pinctrl_gpio_range byt_ranges[] = {
        {
                .name = "1", /* match with acpi _UID in probe */
                .npins = BYT_NGPIO_SCORE,
                .pins = score_pins,
        },
        {
                .name = "2",
                .npins = BYT_NGPIO_NCORE,
                .pins = ncore_pins,
        },
        {
                .name = "3",
                .npins = BYT_NGPIO_SUS,
                .pins = sus_pins,
        },
        {
        },
};

struct byt_gpio {
        struct gpio_chip                chip;
        struct irq_domain               *domain;
        struct platform_device          *pdev;
        spinlock_t                      lock;
        void __iomem                    *reg_base;
        struct pinctrl_gpio_range       *range;
};

#define to_byt_gpio(c)  container_of(c, struct byt_gpio, chip)

static void __iomem *byt_gpio_reg(struct gpio_chip *chip, unsigned offset,
                                 int reg)
{
        struct byt_gpio *vg = to_byt_gpio(chip);
        u32 reg_offset;

        if (reg == BYT_INT_STAT_REG)
                reg_offset = (offset / 32) * 4;
        else
                reg_offset = vg->range->pins[offset] * 16;

        return vg->reg_base + reg_offset + reg;
}

static int byt_gpio_request(struct gpio_chip *chip, unsigned offset)
{
        struct byt_gpio *vg = to_byt_gpio(chip);

        pm_runtime_get(&vg->pdev->dev);

        return 0;
}

static void byt_gpio_free(struct gpio_chip *chip, unsigned offset)
{
        struct byt_gpio *vg = to_byt_gpio(chip);
        void __iomem *reg = byt_gpio_reg(&vg->chip, offset, BYT_CONF0_REG);
        u32 value;

        /* clear interrupt triggering */
        value = readl(reg);
        value &= ~(BYT_TRIG_POS | BYT_TRIG_NEG | BYT_TRIG_LVL);
        writel(value, reg);

        pm_runtime_put(&vg->pdev->dev);
}

static int byt_irq_type(struct irq_data *d, unsigned type)
{
        struct byt_gpio *vg = irq_data_get_irq_chip_data(d);
        u32 offset = irqd_to_hwirq(d);
        u32 value;
        unsigned long flags;
        void __iomem *reg = byt_gpio_reg(&vg->chip, offset, BYT_CONF0_REG);

        if (offset >= vg->chip.ngpio)
                return -EINVAL;

        spin_lock_irqsave(&vg->lock, flags);
        value = readl(reg);

        /* For level trigges the BYT_TRIG_POS and BYT_TRIG_NEG bits
         * are used to indicate high and low level triggering
         */
        value &= ~(BYT_TRIG_POS | BYT_TRIG_NEG | BYT_TRIG_LVL);

        switch (type) {
        case IRQ_TYPE_LEVEL_HIGH:
                value |= BYT_TRIG_LVL;
        case IRQ_TYPE_EDGE_RISING:
                value |= BYT_TRIG_POS;
                break;
        case IRQ_TYPE_LEVEL_LOW:
                value |= BYT_TRIG_LVL;
        case IRQ_TYPE_EDGE_FALLING:
                value |= BYT_TRIG_NEG;
                break;
        case IRQ_TYPE_EDGE_BOTH:
                value |= (BYT_TRIG_NEG | BYT_TRIG_POS);
                break;
        }
        writel(value, reg);

        spin_unlock_irqrestore(&vg->lock, flags);

        return 0;
}

static int byt_gpio_get(struct gpio_chip *chip, unsigned offset)
{
        void __iomem *reg = byt_gpio_reg(chip, offset, BYT_VAL_REG);
        return readl(reg) & BYT_LEVEL;
}

static void byt_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
{
        struct byt_gpio *vg = to_byt_gpio(chip);
        void __iomem *reg = byt_gpio_reg(chip, offset, BYT_VAL_REG);
        unsigned long flags;
        u32 old_val;

        spin_lock_irqsave(&vg->lock, flags);

        old_val = readl(reg);

        if (value)
                writel(old_val | BYT_LEVEL, reg);
        else
                writel(old_val & ~BYT_LEVEL, reg);

        spin_unlock_irqrestore(&vg->lock, flags);
}

static int byt_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
{
        struct byt_gpio *vg = to_byt_gpio(chip);
        void __iomem *reg = byt_gpio_reg(chip, offset, BYT_VAL_REG);
        unsigned long flags;
        u32 value;

        spin_lock_irqsave(&vg->lock, flags);

        value = readl(reg) | BYT_DIR_MASK;
        value &= ~BYT_INPUT_EN;         /* active low */
        writel(value, reg);

        spin_unlock_irqrestore(&vg->lock, flags);

        return 0;
}

static int byt_gpio_direction_output(struct gpio_chip *chip,
                                     unsigned gpio, int value)
{
        struct byt_gpio *vg = to_byt_gpio(chip);
        void __iomem *reg = byt_gpio_reg(chip, gpio, BYT_VAL_REG);
        unsigned long flags;
        u32 reg_val;

        spin_lock_irqsave(&vg->lock, flags);

        reg_val = readl(reg) | BYT_DIR_MASK;
        reg_val &= ~BYT_OUTPUT_EN;

        if (value)
                writel(reg_val | BYT_LEVEL, reg);
        else
                writel(reg_val & ~BYT_LEVEL, reg);

        spin_unlock_irqrestore(&vg->lock, flags);

        return 0;
}

static void byt_gpio_dbg_show(struct seq_file *s, struct gpio_chip *chip)
{
        struct byt_gpio *vg = to_byt_gpio(chip);
        int i;
        unsigned long flags;
        u32 conf0, val, offs;

        spin_lock_irqsave(&vg->lock, flags);

        for (i = 0; i < vg->chip.ngpio; i++) {
                offs = vg->range->pins[i] * 16;
                conf0 = readl(vg->reg_base + offs + BYT_CONF0_REG);
                val = readl(vg->reg_base + offs + BYT_VAL_REG);

                seq_printf(s,
                           " gpio-%-3d %s %s %s pad-%-3d offset:0x%03x mux:%d %s%s%s\n",
                           i,
                           val & BYT_INPUT_EN ? "  " : "in",
                           val & BYT_OUTPUT_EN ? "   " : "out",
                           val & BYT_LEVEL ? "hi" : "lo",
                           vg->range->pins[i], offs,
                           conf0 & 0x7,
                           conf0 & BYT_TRIG_NEG ? " fall" : "",
                           conf0 & BYT_TRIG_POS ? " rise" : "",
                           conf0 & BYT_TRIG_LVL ? " level" : "");
        }
        spin_unlock_irqrestore(&vg->lock, flags);
}

static int byt_gpio_to_irq(struct gpio_chip *chip, unsigned offset)
{
        struct byt_gpio *vg = to_byt_gpio(chip);
        return irq_create_mapping(vg->domain, offset);
}

static void byt_gpio_irq_handler(unsigned irq, struct irq_desc *desc)
{
        struct irq_data *data = irq_desc_get_irq_data(desc);
        struct byt_gpio *vg = irq_data_get_irq_handler_data(data);
        struct irq_chip *chip = irq_data_get_irq_chip(data);
        u32 base, pin, mask;
        void __iomem *reg;
        u32 pending;
        unsigned virq;
        int looplimit = 0;

        /* check from GPIO controller which pin triggered the interrupt */
        for (base = 0; base < vg->chip.ngpio; base += 32) {

                reg = byt_gpio_reg(&vg->chip, base, BYT_INT_STAT_REG);

                while ((pending = readl(reg))) {
                        pin = __ffs(pending);
                        mask = BIT(pin);
                        /* Clear before handling so we can't lose an edge */
                        writel(mask, reg);

                        virq = irq_find_mapping(vg->domain, base + pin);
                        generic_handle_irq(virq);

                        /* In case bios or user sets triggering incorretly a pin
                         * might remain in "interrupt triggered" state.
                         */
                        if (looplimit++ > 32) {
                                dev_err(&vg->pdev->dev,
                                        "Gpio %d interrupt flood, disabling\n",
                                        base + pin);

                                reg = byt_gpio_reg(&vg->chip, base + pin,
                                                   BYT_CONF0_REG);
                                mask = readl(reg);
                                mask &= ~(BYT_TRIG_NEG | BYT_TRIG_POS |
                                          BYT_TRIG_LVL);
                                writel(mask, reg);
                                mask = readl(reg); /* flush */
                                break;
                        }
                }
        }
        chip->irq_eoi(data);
}

static void byt_irq_unmask(struct irq_data *d)
{
}

static void byt_irq_mask(struct irq_data *d)
{
}

static struct irq_chip byt_irqchip = {
        .name = "BYT-GPIO",
        .irq_mask = byt_irq_mask,
        .irq_unmask = byt_irq_unmask,
        .irq_set_type = byt_irq_type,
};

static void byt_gpio_irq_init_hw(struct byt_gpio *vg)
{
        void __iomem *reg;
        u32 base, value;

        /* clear interrupt status trigger registers */
        for (base = 0; base < vg->chip.ngpio; base += 32) {
                reg = byt_gpio_reg(&vg->chip, base, BYT_INT_STAT_REG);
                writel(0xffffffff, reg);
                /* make sure trigger bits are cleared, if not then a pin
                   might be misconfigured in bios */
                value = readl(reg);
                if (value)
                        dev_err(&vg->pdev->dev,
                                "GPIO interrupt error, pins misconfigured\n");
        }
}

static int byt_gpio_irq_map(struct irq_domain *d, unsigned int virq,
                            irq_hw_number_t hw)
{
        struct byt_gpio *vg = d->host_data;

        irq_set_chip_and_handler_name(virq, &byt_irqchip, handle_simple_irq,
                                      "demux");
        irq_set_chip_data(virq, vg);
        irq_set_irq_type(virq, IRQ_TYPE_NONE);

        return 0;
}

static const struct irq_domain_ops byt_gpio_irq_ops = {
        .map = byt_gpio_irq_map,
};

static int byt_gpio_probe(struct platform_device *pdev)
{
        struct byt_gpio *vg;
        struct gpio_chip *gc;
        struct resource *mem_rc, *irq_rc;
        struct device *dev = &pdev->dev;
        struct acpi_device *acpi_dev;
        struct pinctrl_gpio_range *range;
        acpi_handle handle = ACPI_HANDLE(dev);
        unsigned hwirq;
        int ret;

        if (acpi_bus_get_device(handle, &acpi_dev))
                return -ENODEV;

        vg = devm_kzalloc(dev, sizeof(struct byt_gpio), GFP_KERNEL);
        if (!vg) {
                dev_err(&pdev->dev, "can't allocate byt_gpio chip data\n");
                return -ENOMEM;
        }

        for (range = byt_ranges; range->name; range++) {
                if (!strcmp(acpi_dev->pnp.unique_id, range->name)) {
                        vg->chip.ngpio = range->npins;
                        vg->range = range;
                        break;
                }
        }

        if (!vg->chip.ngpio || !vg->range)
                return -ENODEV;

        vg->pdev = pdev;
        platform_set_drvdata(pdev, vg);

        mem_rc = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        vg->reg_base = devm_ioremap_resource(dev, mem_rc);
        if (IS_ERR(vg->reg_base))
                return PTR_ERR(vg->reg_base);

        spin_lock_init(&vg->lock);

        gc = &vg->chip;
        gc->label = dev_name(&pdev->dev);
        gc->owner = THIS_MODULE;
        gc->request = byt_gpio_request;
        gc->free = byt_gpio_free;
        gc->direction_input = byt_gpio_direction_input;
        gc->direction_output = byt_gpio_direction_output;
        gc->get = byt_gpio_get;
        gc->set = byt_gpio_set;
        gc->dbg_show = byt_gpio_dbg_show;
        gc->base = -1;
        gc->can_sleep = 0;
        gc->dev = dev;

        ret = gpiochip_add(gc);
        if (ret) {
                dev_err(&pdev->dev, "failed adding byt-gpio chip\n");
                return ret;
        }

        /* set up interrupts  */
        irq_rc = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
        if (irq_rc && irq_rc->start) {
                hwirq = irq_rc->start;
                gc->to_irq = byt_gpio_to_irq;

                vg->domain = irq_domain_add_linear(NULL, gc->ngpio,
                                                   &byt_gpio_irq_ops, vg);
                if (!vg->domain)
                        return -ENXIO;

                byt_gpio_irq_init_hw(vg);

                irq_set_handler_data(hwirq, vg);
                irq_set_chained_handler(hwirq, byt_gpio_irq_handler);

                /* Register interrupt handlers for gpio signaled acpi events */
                acpi_gpiochip_request_interrupts(gc);
        }

        pm_runtime_enable(dev);

        return 0;
}

static int byt_gpio_runtime_suspend(struct device *dev)
{
        return 0;
}

static int byt_gpio_runtime_resume(struct device *dev)
{
        return 0;
}

static const struct dev_pm_ops byt_gpio_pm_ops = {
        .runtime_suspend = byt_gpio_runtime_suspend,
        .runtime_resume = byt_gpio_runtime_resume,
};

static const struct acpi_device_id byt_gpio_acpi_match[] = {
        { "INT33B2", 0 },
        { }
};
MODULE_DEVICE_TABLE(acpi, byt_gpio_acpi_match);

static int byt_gpio_remove(struct platform_device *pdev)
{
        struct byt_gpio *vg = platform_get_drvdata(pdev);
        int err;

        pm_runtime_disable(&pdev->dev);
        err = gpiochip_remove(&vg->chip);
        if (err)
                dev_warn(&pdev->dev, "failed to remove gpio_chip.\n");

        return 0;
}

static struct platform_driver byt_gpio_driver = {
        .probe          = byt_gpio_probe,
        .remove         = byt_gpio_remove,
        .driver         = {
                .name   = "byt_gpio",
                .owner  = THIS_MODULE,
                .pm     = &byt_gpio_pm_ops,
                .acpi_match_table = ACPI_PTR(byt_gpio_acpi_match),
        },
};

static int __init byt_gpio_init(void)
{
        return platform_driver_register(&byt_gpio_driver);
}

subsys_initcall(byt_gpio_init);