/*
 * Intel MID GPIO driver
 *
 * Copyright (c) 2008-2014,2016 Intel Corporation.
 *
 * 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.
 *
 * This program is distributed in the hope that 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.
 */

/* Supports:
 * Moorestown platform Langwell chip.
 * Medfield platform Penwell chip.
 * Clovertrail platform Cloverview chip.
 */

#include <linux/delay.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/gpio/driver.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/slab.h>
#include <linux/stddef.h>

#define INTEL_MID_IRQ_TYPE_EDGE         (1 << 0)
#define INTEL_MID_IRQ_TYPE_LEVEL        (1 << 1)

/*
 * Langwell chip has 64 pins and thus there are 2 32bit registers to control
 * each feature, while Penwell chip has 96 pins for each block, and need 3 32bit
 * registers to control them, so we only define the order here instead of a
 * structure, to get a bit offset for a pin (use GPDR as an example):
 *
 * nreg = ngpio / 32;
 * reg = offset / 32;
 * bit = offset % 32;
 * reg_addr = reg_base + GPDR * nreg * 4 + reg * 4;
 *
 * so the bit of reg_addr is to control pin offset's GPDR feature
*/

enum GPIO_REG {
        GPLR = 0,       /* pin level read-only */
        GPDR,           /* pin direction */
        GPSR,           /* pin set */
        GPCR,           /* pin clear */
        GRER,           /* rising edge detect */
        GFER,           /* falling edge detect */
        GEDR,           /* edge detect result */
        GAFR,           /* alt function */
};

/* intel_mid gpio driver data */
struct intel_mid_gpio_ddata {
        u16 ngpio;              /* number of gpio pins */
        u32 chip_irq_type;      /* chip interrupt type */
};

struct intel_mid_gpio {
        struct gpio_chip                chip;
        void __iomem                    *reg_base;
        spinlock_t                      lock;
        struct pci_dev                  *pdev;
};

static void __iomem *gpio_reg(struct gpio_chip *chip, unsigned offset,
                              enum GPIO_REG reg_type)
{
        struct intel_mid_gpio *priv = gpiochip_get_data(chip);
        unsigned nreg = chip->ngpio / 32;
        u8 reg = offset / 32;

        return priv->reg_base + reg_type * nreg * 4 + reg * 4;
}

static void __iomem *gpio_reg_2bit(struct gpio_chip *chip, unsigned offset,
                                   enum GPIO_REG reg_type)
{
        struct intel_mid_gpio *priv = gpiochip_get_data(chip);
        unsigned nreg = chip->ngpio / 32;
        u8 reg = offset / 16;

        return priv->reg_base + reg_type * nreg * 4 + reg * 4;
}

static int intel_gpio_request(struct gpio_chip *chip, unsigned offset)
{
        void __iomem *gafr = gpio_reg_2bit(chip, offset, GAFR);
        u32 value = readl(gafr);
        int shift = (offset % 16) << 1, af = (value >> shift) & 3;

        if (af) {
                value &= ~(3 << shift);
                writel(value, gafr);
        }
        return 0;
}

static int intel_gpio_get(struct gpio_chip *chip, unsigned offset)
{
        void __iomem *gplr = gpio_reg(chip, offset, GPLR);

        return !!(readl(gplr) & BIT(offset % 32));
}

static void intel_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
{
        void __iomem *gpsr, *gpcr;

        if (value) {
                gpsr = gpio_reg(chip, offset, GPSR);
                writel(BIT(offset % 32), gpsr);
        } else {
                gpcr = gpio_reg(chip, offset, GPCR);
                writel(BIT(offset % 32), gpcr);
        }
}

static int intel_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
{
        struct intel_mid_gpio *priv = gpiochip_get_data(chip);
        void __iomem *gpdr = gpio_reg(chip, offset, GPDR);
        u32 value;
        unsigned long flags;

        if (priv->pdev)
                pm_runtime_get(&priv->pdev->dev);

        spin_lock_irqsave(&priv->lock, flags);
        value = readl(gpdr);
        value &= ~BIT(offset % 32);
        writel(value, gpdr);
        spin_unlock_irqrestore(&priv->lock, flags);

        if (priv->pdev)
                pm_runtime_put(&priv->pdev->dev);

        return 0;
}

static int intel_gpio_direction_output(struct gpio_chip *chip,
                        unsigned offset, int value)
{
        struct intel_mid_gpio *priv = gpiochip_get_data(chip);
        void __iomem *gpdr = gpio_reg(chip, offset, GPDR);
        unsigned long flags;

        intel_gpio_set(chip, offset, value);

        if (priv->pdev)
                pm_runtime_get(&priv->pdev->dev);

        spin_lock_irqsave(&priv->lock, flags);
        value = readl(gpdr);
        value |= BIT(offset % 32);
        writel(value, gpdr);
        spin_unlock_irqrestore(&priv->lock, flags);

        if (priv->pdev)
                pm_runtime_put(&priv->pdev->dev);

        return 0;
}

static int intel_mid_irq_type(struct irq_data *d, unsigned type)
{
        struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
        struct intel_mid_gpio *priv = gpiochip_get_data(gc);
        u32 gpio = irqd_to_hwirq(d);
        unsigned long flags;
        u32 value;
        void __iomem *grer = gpio_reg(&priv->chip, gpio, GRER);
        void __iomem *gfer = gpio_reg(&priv->chip, gpio, GFER);

        if (gpio >= priv->chip.ngpio)
                return -EINVAL;

        if (priv->pdev)
                pm_runtime_get(&priv->pdev->dev);

        spin_lock_irqsave(&priv->lock, flags);
        if (type & IRQ_TYPE_EDGE_RISING)
                value = readl(grer) | BIT(gpio % 32);
        else
                value = readl(grer) & (~BIT(gpio % 32));
        writel(value, grer);

        if (type & IRQ_TYPE_EDGE_FALLING)
                value = readl(gfer) | BIT(gpio % 32);
        else
                value = readl(gfer) & (~BIT(gpio % 32));
        writel(value, gfer);
        spin_unlock_irqrestore(&priv->lock, flags);

        if (priv->pdev)
                pm_runtime_put(&priv->pdev->dev);

        return 0;
}

static void intel_mid_irq_unmask(struct irq_data *d)
{
}

static void intel_mid_irq_mask(struct irq_data *d)
{
}

static struct irq_chip intel_mid_irqchip = {
        .name           = "INTEL_MID-GPIO",
        .irq_mask       = intel_mid_irq_mask,
        .irq_unmask     = intel_mid_irq_unmask,
        .irq_set_type   = intel_mid_irq_type,
};

static const struct intel_mid_gpio_ddata gpio_lincroft = {
        .ngpio = 64,
};

static const struct intel_mid_gpio_ddata gpio_penwell_aon = {
        .ngpio = 96,
        .chip_irq_type = INTEL_MID_IRQ_TYPE_EDGE,
};

static const struct intel_mid_gpio_ddata gpio_penwell_core = {
        .ngpio = 96,
        .chip_irq_type = INTEL_MID_IRQ_TYPE_EDGE,
};

static const struct intel_mid_gpio_ddata gpio_cloverview_aon = {
        .ngpio = 96,
        .chip_irq_type = INTEL_MID_IRQ_TYPE_EDGE | INTEL_MID_IRQ_TYPE_LEVEL,
};

static const struct intel_mid_gpio_ddata gpio_cloverview_core = {
        .ngpio = 96,
        .chip_irq_type = INTEL_MID_IRQ_TYPE_EDGE,
};

static const struct pci_device_id intel_gpio_ids[] = {
        {
                /* Lincroft */
                PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x080f),
                .driver_data = (kernel_ulong_t)&gpio_lincroft,
        },
        {
                /* Penwell AON */
                PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x081f),
                .driver_data = (kernel_ulong_t)&gpio_penwell_aon,
        },
        {
                /* Penwell Core */
                PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x081a),
                .driver_data = (kernel_ulong_t)&gpio_penwell_core,
        },
        {
                /* Cloverview Aon */
                PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x08eb),
                .driver_data = (kernel_ulong_t)&gpio_cloverview_aon,
        },
        {
                /* Cloverview Core */
                PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x08f7),
                .driver_data = (kernel_ulong_t)&gpio_cloverview_core,
        },
        { 0 }
};
MODULE_DEVICE_TABLE(pci, intel_gpio_ids);

static void intel_mid_irq_handler(struct irq_desc *desc)
{
        struct gpio_chip *gc = irq_desc_get_handler_data(desc);
        struct intel_mid_gpio *priv = gpiochip_get_data(gc);
        struct irq_data *data = irq_desc_get_irq_data(desc);
        struct irq_chip *chip = irq_data_get_irq_chip(data);
        u32 base, gpio, mask;
        unsigned long pending;
        void __iomem *gedr;

        /* check GPIO controller to check which pin triggered the interrupt */
        for (base = 0; base < priv->chip.ngpio; base += 32) {
                gedr = gpio_reg(&priv->chip, base, GEDR);
                while ((pending = readl(gedr))) {
                        gpio = __ffs(pending);
                        mask = BIT(gpio);
                        /* Clear before handling so we can't lose an edge */
                        writel(mask, gedr);
                        generic_handle_irq(irq_find_mapping(gc->irqdomain,
                                                            base + gpio));
                }
        }

        chip->irq_eoi(data);
}

static void intel_mid_irq_init_hw(struct intel_mid_gpio *priv)
{
        void __iomem *reg;
        unsigned base;

        for (base = 0; base < priv->chip.ngpio; base += 32) {
                /* Clear the rising-edge detect register */
                reg = gpio_reg(&priv->chip, base, GRER);
                writel(0, reg);
                /* Clear the falling-edge detect register */
                reg = gpio_reg(&priv->chip, base, GFER);
                writel(0, reg);
                /* Clear the edge detect status register */
                reg = gpio_reg(&priv->chip, base, GEDR);
                writel(~0, reg);
        }
}

static int intel_gpio_runtime_idle(struct device *dev)
{
        int err = pm_schedule_suspend(dev, 500);
        return err ?: -EBUSY;
}

static const struct dev_pm_ops intel_gpio_pm_ops = {
        SET_RUNTIME_PM_OPS(NULL, NULL, intel_gpio_runtime_idle)
};

static int intel_gpio_probe(struct pci_dev *pdev,
                          const struct pci_device_id *id)
{
        void __iomem *base;
        struct intel_mid_gpio *priv;
        u32 gpio_base;
        u32 irq_base;
        int retval;
        struct intel_mid_gpio_ddata *ddata =
                                (struct intel_mid_gpio_ddata *)id->driver_data;

        retval = pcim_enable_device(pdev);
        if (retval)
                return retval;

        retval = pcim_iomap_regions(pdev, 1 << 0 | 1 << 1, pci_name(pdev));
        if (retval) {
                dev_err(&pdev->dev, "I/O memory mapping error\n");
                return retval;
        }

        base = pcim_iomap_table(pdev)[1];

        irq_base = readl(base);
        gpio_base = readl(sizeof(u32) + base);

        /* release the IO mapping, since we already get the info from bar1 */
        pcim_iounmap_regions(pdev, 1 << 1);

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

        priv->reg_base = pcim_iomap_table(pdev)[0];
        priv->chip.label = dev_name(&pdev->dev);
        priv->chip.parent = &pdev->dev;
        priv->chip.request = intel_gpio_request;
        priv->chip.direction_input = intel_gpio_direction_input;
        priv->chip.direction_output = intel_gpio_direction_output;
        priv->chip.get = intel_gpio_get;
        priv->chip.set = intel_gpio_set;
        priv->chip.base = gpio_base;
        priv->chip.ngpio = ddata->ngpio;
        priv->chip.can_sleep = false;
        priv->pdev = pdev;

        spin_lock_init(&priv->lock);

        pci_set_drvdata(pdev, priv);
        retval = devm_gpiochip_add_data(&pdev->dev, &priv->chip, priv);
        if (retval) {
                dev_err(&pdev->dev, "gpiochip_add error %d\n", retval);
                return retval;
        }

        retval = gpiochip_irqchip_add(&priv->chip,
                                      &intel_mid_irqchip,
                                      irq_base,
                                      handle_simple_irq,
                                      IRQ_TYPE_NONE);
        if (retval) {
                dev_err(&pdev->dev,
                        "could not connect irqchip to gpiochip\n");
                return retval;
        }

        intel_mid_irq_init_hw(priv);

        gpiochip_set_chained_irqchip(&priv->chip,
                                     &intel_mid_irqchip,
                                     pdev->irq,
                                     intel_mid_irq_handler);

        pm_runtime_put_noidle(&pdev->dev);
        pm_runtime_allow(&pdev->dev);

        return 0;
}

static struct pci_driver intel_gpio_driver = {
        .name           = "intel_mid_gpio",
        .id_table       = intel_gpio_ids,
        .probe          = intel_gpio_probe,
        .driver         = {
                .pm     = &intel_gpio_pm_ops,
        },
};

static int __init intel_gpio_init(void)
{
        return pci_register_driver(&intel_gpio_driver);
}

device_initcall(intel_gpio_init);