/*
 * Toumaz Xenif TZ1090 PDC GPIO handling.
 *
 * Copyright (C) 2012-2013 Imagination Technologies Ltd.
 *
 * 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/gpio.h>
#include <linux/io.h>
#include <linux/module.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 SOC_GPIO_CONTROL0 */
#define REG_SOC_GPIO_CONTROL0   0x00
#define REG_SOC_GPIO_CONTROL1   0x04
#define REG_SOC_GPIO_CONTROL2   0x08
#define REG_SOC_GPIO_CONTROL3   0x0c
#define REG_SOC_GPIO_STATUS     0x80

/* PDC GPIOs go after normal GPIOs */
#define GPIO_PDC_BASE           90
#define GPIO_PDC_NGPIO          7

/* Out of PDC gpios, only syswakes have irqs */
#define GPIO_PDC_IRQ_FIRST      2
#define GPIO_PDC_NIRQ           3

/**
 * struct tz1090_pdc_gpio - GPIO bank private data
 * @chip:       Generic GPIO chip for GPIO bank
 * @reg:        Base of registers, offset for this GPIO bank
 * @irq:        IRQ numbers for Syswake GPIOs
 *
 * This is the main private data for the PDC GPIO driver. It encapsulates a
 * gpio_chip, and the callbacks for the gpio_chip can access the private data
 * with the to_pdc() macro below.
 */
struct tz1090_pdc_gpio {
        struct gpio_chip chip;
        void __iomem *reg;
        int irq[GPIO_PDC_NIRQ];
};

/* Register accesses into the PDC MMIO area */

static inline void pdc_write(struct tz1090_pdc_gpio *priv, unsigned int reg_offs,
                      unsigned int data)
{
        writel(data, priv->reg + reg_offs);
}

static inline unsigned int pdc_read(struct tz1090_pdc_gpio *priv,
                             unsigned int reg_offs)
{
        return readl(priv->reg + reg_offs);
}

/* Generic GPIO interface */

static int tz1090_pdc_gpio_direction_input(struct gpio_chip *chip,
                                           unsigned int offset)
{
        struct tz1090_pdc_gpio *priv = gpiochip_get_data(chip);
        u32 value;
        int lstat;

        __global_lock2(lstat);
        value = pdc_read(priv, REG_SOC_GPIO_CONTROL1);
        value |= BIT(offset);
        pdc_write(priv, REG_SOC_GPIO_CONTROL1, value);
        __global_unlock2(lstat);

        return 0;
}

static int tz1090_pdc_gpio_direction_output(struct gpio_chip *chip,
                                            unsigned int offset,
                                            int output_value)
{
        struct tz1090_pdc_gpio *priv = gpiochip_get_data(chip);
        u32 value;
        int lstat;

        __global_lock2(lstat);
        /* EXT_POWER doesn't seem to have an output value bit */
        if (offset < 6) {
                value = pdc_read(priv, REG_SOC_GPIO_CONTROL0);
                if (output_value)
                        value |= BIT(offset);
                else
                        value &= ~BIT(offset);
                pdc_write(priv, REG_SOC_GPIO_CONTROL0, value);
        }

        value = pdc_read(priv, REG_SOC_GPIO_CONTROL1);
        value &= ~BIT(offset);
        pdc_write(priv, REG_SOC_GPIO_CONTROL1, value);
        __global_unlock2(lstat);

        return 0;
}

static int tz1090_pdc_gpio_get(struct gpio_chip *chip, unsigned int offset)
{
        struct tz1090_pdc_gpio *priv = gpiochip_get_data(chip);
        return !!(pdc_read(priv, REG_SOC_GPIO_STATUS) & BIT(offset));
}

static void tz1090_pdc_gpio_set(struct gpio_chip *chip, unsigned int offset,
                                int output_value)
{
        struct tz1090_pdc_gpio *priv = gpiochip_get_data(chip);
        u32 value;
        int lstat;

        /* EXT_POWER doesn't seem to have an output value bit */
        if (offset >= 6)
                return;

        __global_lock2(lstat);
        value = pdc_read(priv, REG_SOC_GPIO_CONTROL0);
        if (output_value)
                value |= BIT(offset);
        else
                value &= ~BIT(offset);
        pdc_write(priv, REG_SOC_GPIO_CONTROL0, value);
        __global_unlock2(lstat);
}

static int tz1090_pdc_gpio_to_irq(struct gpio_chip *chip, unsigned int offset)
{
        struct tz1090_pdc_gpio *priv = gpiochip_get_data(chip);
        unsigned int syswake = offset - GPIO_PDC_IRQ_FIRST;
        int irq;

        /* only syswakes have irqs */
        if (syswake >= GPIO_PDC_NIRQ)
                return -EINVAL;

        irq = priv->irq[syswake];
        if (!irq)
                return -EINVAL;

        return irq;
}

static int tz1090_pdc_gpio_probe(struct platform_device *pdev)
{
        struct device_node *np = pdev->dev.of_node;
        struct resource *res_regs;
        struct tz1090_pdc_gpio *priv;
        unsigned int i;

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

        /* 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;
        }

        /* Set up GPIO chip */
        priv->chip.label                = "tz1090-pdc-gpio";
        priv->chip.parent               = &pdev->dev;
        priv->chip.direction_input      = tz1090_pdc_gpio_direction_input;
        priv->chip.direction_output     = tz1090_pdc_gpio_direction_output;
        priv->chip.get                  = tz1090_pdc_gpio_get;
        priv->chip.set                  = tz1090_pdc_gpio_set;
        priv->chip.free                 = gpiochip_generic_free;
        priv->chip.request              = gpiochip_generic_request;
        priv->chip.to_irq               = tz1090_pdc_gpio_to_irq;
        priv->chip.of_node              = np;

        /* GPIO numbering */
        priv->chip.base                 = GPIO_PDC_BASE;
        priv->chip.ngpio                = GPIO_PDC_NGPIO;

        /* Map the syswake irqs */
        for (i = 0; i < GPIO_PDC_NIRQ; ++i)
                priv->irq[i] = irq_of_parse_and_map(np, i);

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

        return 0;
}

static struct of_device_id tz1090_pdc_gpio_of_match[] = {
        { .compatible = "img,tz1090-pdc-gpio" },
        { },
};

static struct platform_driver tz1090_pdc_gpio_driver = {
        .driver = {
                .name           = "tz1090-pdc-gpio",
                .of_match_table = tz1090_pdc_gpio_of_match,
        },
        .probe          = tz1090_pdc_gpio_probe,
};

static int __init tz1090_pdc_gpio_init(void)
{
        return platform_driver_register(&tz1090_pdc_gpio_driver);
}
subsys_initcall(tz1090_pdc_gpio_init);