/*
 * SPEAr platform PLGPIO driver
 *
 * Copyright (C) 2012 ST Microelectronics
 * Viresh Kumar <viresh.kumar@linaro.org>
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#include <linux/clk.h>
#include <linux/err.h>
#include <linux/gpio/driver.h>
#include <linux/io.h>
#include <linux/init.h>
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/pinctrl/consumer.h>
#include <linux/platform_device.h>
#include <linux/pm.h>
#include <linux/spinlock.h>

#define MAX_GPIO_PER_REG                32
#define PIN_OFFSET(pin)                 (pin % MAX_GPIO_PER_REG)
#define REG_OFFSET(base, reg, pin)      (base + reg + (pin / MAX_GPIO_PER_REG) \
                                                        * sizeof(int *))

/*
 * plgpio pins in all machines are not one to one mapped, bitwise with registers
 * bits. These set of macros define register masks for which below functions
 * (pin_to_offset and offset_to_pin) are required to be called.
 */
#define PTO_ENB_REG             0x001
#define PTO_WDATA_REG           0x002
#define PTO_DIR_REG             0x004
#define PTO_IE_REG              0x008
#define PTO_RDATA_REG           0x010
#define PTO_MIS_REG             0x020

struct plgpio_regs {
        u32 enb;                /* enable register */
        u32 wdata;              /* write data register */
        u32 dir;                /* direction set register */
        u32 rdata;              /* read data register */
        u32 ie;                 /* interrupt enable register */
        u32 mis;                /* mask interrupt status register */
        u32 eit;                /* edge interrupt type */
};

/*
 * struct plgpio: plgpio driver specific structure
 *
 * lock: lock for guarding gpio registers
 * base: base address of plgpio block
 * chip: gpio framework specific chip information structure
 * p2o: function ptr for pin to offset conversion. This is required only for
 *      machines where mapping b/w pin and offset is not 1-to-1.
 * o2p: function ptr for offset to pin conversion. This is required only for
 *      machines where mapping b/w pin and offset is not 1-to-1.
 * p2o_regs: mask of registers for which p2o and o2p are applicable
 * regs: register offsets
 * csave_regs: context save registers for standby/sleep/hibernate cases
 */
struct plgpio {
        spinlock_t              lock;
        void __iomem            *base;
        struct clk              *clk;
        struct gpio_chip        chip;
        int                     (*p2o)(int pin);        /* pin_to_offset */
        int                     (*o2p)(int offset);     /* offset_to_pin */
        u32                     p2o_regs;
        struct plgpio_regs      regs;
#ifdef CONFIG_PM_SLEEP
        struct plgpio_regs      *csave_regs;
#endif
};

/* register manipulation inline functions */
static inline u32 is_plgpio_set(void __iomem *base, u32 pin, u32 reg)
{
        u32 offset = PIN_OFFSET(pin);
        void __iomem *reg_off = REG_OFFSET(base, reg, pin);
        u32 val = readl_relaxed(reg_off);

        return !!(val & (1 << offset));
}

static inline void plgpio_reg_set(void __iomem *base, u32 pin, u32 reg)
{
        u32 offset = PIN_OFFSET(pin);
        void __iomem *reg_off = REG_OFFSET(base, reg, pin);
        u32 val = readl_relaxed(reg_off);

        writel_relaxed(val | (1 << offset), reg_off);
}

static inline void plgpio_reg_reset(void __iomem *base, u32 pin, u32 reg)
{
        u32 offset = PIN_OFFSET(pin);
        void __iomem *reg_off = REG_OFFSET(base, reg, pin);
        u32 val = readl_relaxed(reg_off);

        writel_relaxed(val & ~(1 << offset), reg_off);
}

/* gpio framework specific routines */
static int plgpio_direction_input(struct gpio_chip *chip, unsigned offset)
{
        struct plgpio *plgpio = gpiochip_get_data(chip);
        unsigned long flags;

        /* get correct offset for "offset" pin */
        if (plgpio->p2o && (plgpio->p2o_regs & PTO_DIR_REG)) {
                offset = plgpio->p2o(offset);
                if (offset == -1)
                        return -EINVAL;
        }

        spin_lock_irqsave(&plgpio->lock, flags);
        plgpio_reg_set(plgpio->base, offset, plgpio->regs.dir);
        spin_unlock_irqrestore(&plgpio->lock, flags);

        return 0;
}

static int plgpio_direction_output(struct gpio_chip *chip, unsigned offset,
                int value)
{
        struct plgpio *plgpio = gpiochip_get_data(chip);
        unsigned long flags;
        unsigned dir_offset = offset, wdata_offset = offset, tmp;

        /* get correct offset for "offset" pin */
        if (plgpio->p2o && (plgpio->p2o_regs & (PTO_DIR_REG | PTO_WDATA_REG))) {
                tmp = plgpio->p2o(offset);
                if (tmp == -1)
                        return -EINVAL;

                if (plgpio->p2o_regs & PTO_DIR_REG)
                        dir_offset = tmp;
                if (plgpio->p2o_regs & PTO_WDATA_REG)
                        wdata_offset = tmp;
        }

        spin_lock_irqsave(&plgpio->lock, flags);
        if (value)
                plgpio_reg_set(plgpio->base, wdata_offset,
                                plgpio->regs.wdata);
        else
                plgpio_reg_reset(plgpio->base, wdata_offset,
                                plgpio->regs.wdata);

        plgpio_reg_reset(plgpio->base, dir_offset, plgpio->regs.dir);
        spin_unlock_irqrestore(&plgpio->lock, flags);

        return 0;
}

static int plgpio_get_value(struct gpio_chip *chip, unsigned offset)
{
        struct plgpio *plgpio = gpiochip_get_data(chip);

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

        /* get correct offset for "offset" pin */
        if (plgpio->p2o && (plgpio->p2o_regs & PTO_RDATA_REG)) {
                offset = plgpio->p2o(offset);
                if (offset == -1)
                        return -EINVAL;
        }

        return is_plgpio_set(plgpio->base, offset, plgpio->regs.rdata);
}

static void plgpio_set_value(struct gpio_chip *chip, unsigned offset, int value)
{
        struct plgpio *plgpio = gpiochip_get_data(chip);

        if (offset >= chip->ngpio)
                return;

        /* get correct offset for "offset" pin */
        if (plgpio->p2o && (plgpio->p2o_regs & PTO_WDATA_REG)) {
                offset = plgpio->p2o(offset);
                if (offset == -1)
                        return;
        }

        if (value)
                plgpio_reg_set(plgpio->base, offset, plgpio->regs.wdata);
        else
                plgpio_reg_reset(plgpio->base, offset, plgpio->regs.wdata);
}

static int plgpio_request(struct gpio_chip *chip, unsigned offset)
{
        struct plgpio *plgpio = gpiochip_get_data(chip);
        int gpio = chip->base + offset;
        unsigned long flags;
        int ret = 0;

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

        ret = pinctrl_gpio_request(gpio);
        if (ret)
                return ret;

        if (!IS_ERR(plgpio->clk)) {
                ret = clk_enable(plgpio->clk);
                if (ret)
                        goto err0;
        }

        if (plgpio->regs.enb == -1)
                return 0;

        /*
         * put gpio in IN mode before enabling it. This make enabling gpio safe
         */
        ret = plgpio_direction_input(chip, offset);
        if (ret)
                goto err1;

        /* get correct offset for "offset" pin */
        if (plgpio->p2o && (plgpio->p2o_regs & PTO_ENB_REG)) {
                offset = plgpio->p2o(offset);
                if (offset == -1) {
                        ret = -EINVAL;
                        goto err1;
                }
        }

        spin_lock_irqsave(&plgpio->lock, flags);
        plgpio_reg_set(plgpio->base, offset, plgpio->regs.enb);
        spin_unlock_irqrestore(&plgpio->lock, flags);
        return 0;

err1:
        if (!IS_ERR(plgpio->clk))
                clk_disable(plgpio->clk);
err0:
        pinctrl_gpio_free(gpio);
        return ret;
}

static void plgpio_free(struct gpio_chip *chip, unsigned offset)
{
        struct plgpio *plgpio = gpiochip_get_data(chip);
        int gpio = chip->base + offset;
        unsigned long flags;

        if (offset >= chip->ngpio)
                return;

        if (plgpio->regs.enb == -1)
                goto disable_clk;

        /* get correct offset for "offset" pin */
        if (plgpio->p2o && (plgpio->p2o_regs & PTO_ENB_REG)) {
                offset = plgpio->p2o(offset);
                if (offset == -1)
                        return;
        }

        spin_lock_irqsave(&plgpio->lock, flags);
        plgpio_reg_reset(plgpio->base, offset, plgpio->regs.enb);
        spin_unlock_irqrestore(&plgpio->lock, flags);

disable_clk:
        if (!IS_ERR(plgpio->clk))
                clk_disable(plgpio->clk);

        pinctrl_gpio_free(gpio);
}

/* PLGPIO IRQ */
static void plgpio_irq_disable(struct irq_data *d)
{
        struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
        struct plgpio *plgpio = gpiochip_get_data(gc);
        int offset = d->hwirq;
        unsigned long flags;

        /* get correct offset for "offset" pin */
        if (plgpio->p2o && (plgpio->p2o_regs & PTO_IE_REG)) {
                offset = plgpio->p2o(offset);
                if (offset == -1)
                        return;
        }

        spin_lock_irqsave(&plgpio->lock, flags);
        plgpio_reg_set(plgpio->base, offset, plgpio->regs.ie);
        spin_unlock_irqrestore(&plgpio->lock, flags);
}

static void plgpio_irq_enable(struct irq_data *d)
{
        struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
        struct plgpio *plgpio = gpiochip_get_data(gc);
        int offset = d->hwirq;
        unsigned long flags;

        /* get correct offset for "offset" pin */
        if (plgpio->p2o && (plgpio->p2o_regs & PTO_IE_REG)) {
                offset = plgpio->p2o(offset);
                if (offset == -1)
                        return;
        }

        spin_lock_irqsave(&plgpio->lock, flags);
        plgpio_reg_reset(plgpio->base, offset, plgpio->regs.ie);
        spin_unlock_irqrestore(&plgpio->lock, flags);
}

static int plgpio_irq_set_type(struct irq_data *d, unsigned trigger)
{
        struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
        struct plgpio *plgpio = gpiochip_get_data(gc);
        int offset = d->hwirq;
        void __iomem *reg_off;
        unsigned int supported_type = 0, val;

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

        if (plgpio->regs.eit == -1)
                supported_type = IRQ_TYPE_LEVEL_HIGH;
        else
                supported_type = IRQ_TYPE_EDGE_RISING | IRQ_TYPE_EDGE_FALLING;

        if (!(trigger & supported_type))
                return -EINVAL;

        if (plgpio->regs.eit == -1)
                return 0;

        reg_off = REG_OFFSET(plgpio->base, plgpio->regs.eit, offset);
        val = readl_relaxed(reg_off);

        offset = PIN_OFFSET(offset);
        if (trigger & IRQ_TYPE_EDGE_RISING)
                writel_relaxed(val | (1 << offset), reg_off);
        else
                writel_relaxed(val & ~(1 << offset), reg_off);

        return 0;
}

static struct irq_chip plgpio_irqchip = {
        .name           = "PLGPIO",
        .irq_enable     = plgpio_irq_enable,
        .irq_disable    = plgpio_irq_disable,
        .irq_set_type   = plgpio_irq_set_type,
};

static void plgpio_irq_handler(struct irq_desc *desc)
{
        struct gpio_chip *gc = irq_desc_get_handler_data(desc);
        struct plgpio *plgpio = gpiochip_get_data(gc);
        struct irq_chip *irqchip = irq_desc_get_chip(desc);
        int regs_count, count, pin, offset, i = 0;
        unsigned long pending;

        count = plgpio->chip.ngpio;
        regs_count = DIV_ROUND_UP(count, MAX_GPIO_PER_REG);

        chained_irq_enter(irqchip, desc);
        /* check all plgpio MIS registers for a possible interrupt */
        for (; i < regs_count; i++) {
                pending = readl_relaxed(plgpio->base + plgpio->regs.mis +
                                i * sizeof(int *));
                if (!pending)
                        continue;

                /* clear interrupts */
                writel_relaxed(~pending, plgpio->base + plgpio->regs.mis +
                                i * sizeof(int *));
                /*
                 * clear extra bits in last register having gpios < MAX/REG
                 * ex: Suppose there are max 102 plgpios. then last register
                 * must have only (102 - MAX_GPIO_PER_REG * 3) = 6 relevant bits
                 * so, we must not take other 28 bits into consideration for
                 * checking interrupt. so clear those bits.
                 */
                count = count - i * MAX_GPIO_PER_REG;
                if (count < MAX_GPIO_PER_REG)
                        pending &= (1 << count) - 1;

                for_each_set_bit(offset, &pending, MAX_GPIO_PER_REG) {
                        /* get correct pin for "offset" */
                        if (plgpio->o2p && (plgpio->p2o_regs & PTO_MIS_REG)) {
                                pin = plgpio->o2p(offset);
                                if (pin == -1)
                                        continue;
                        } else
                                pin = offset;

                        /* get correct irq line number */
                        pin = i * MAX_GPIO_PER_REG + pin;
                        generic_handle_irq(
                                irq_find_mapping(gc->irq.domain, pin));
                }
        }
        chained_irq_exit(irqchip, desc);
}

/*
 * pin to offset and offset to pin converter functions
 *
 * In spear310 there is inconsistency among bit positions in plgpio regiseters,
 * for different plgpio pins. For example: for pin 27, bit offset is 23, pin
 * 28-33 are not supported, pin 95 has offset bit 95, bit 100 has offset bit 1
 */
static int spear310_p2o(int pin)
{
        int offset = pin;

        if (pin <= 27)
                offset += 4;
        else if (pin <= 33)
                offset = -1;
        else if (pin <= 97)
                offset -= 2;
        else if (pin <= 101)
                offset = 101 - pin;
        else
                offset = -1;

        return offset;
}

static int spear310_o2p(int offset)
{
        if (offset <= 3)
                return 101 - offset;
        else if (offset <= 31)
                return offset - 4;
        else
                return offset + 2;
}

static int plgpio_probe_dt(struct platform_device *pdev, struct plgpio *plgpio)
{
        struct device_node *np = pdev->dev.of_node;
        int ret = -EINVAL;
        u32 val;

        if (of_machine_is_compatible("st,spear310")) {
                plgpio->p2o = spear310_p2o;
                plgpio->o2p = spear310_o2p;
                plgpio->p2o_regs = PTO_WDATA_REG | PTO_DIR_REG | PTO_IE_REG |
                        PTO_RDATA_REG | PTO_MIS_REG;
        }

        if (!of_property_read_u32(np, "st-plgpio,ngpio", &val)) {
                plgpio->chip.ngpio = val;
        } else {
                dev_err(&pdev->dev, "DT: Invalid ngpio field\n");
                goto end;
        }

        if (!of_property_read_u32(np, "st-plgpio,enb-reg", &val))
                plgpio->regs.enb = val;
        else
                plgpio->regs.enb = -1;

        if (!of_property_read_u32(np, "st-plgpio,wdata-reg", &val)) {
                plgpio->regs.wdata = val;
        } else {
                dev_err(&pdev->dev, "DT: Invalid wdata reg\n");
                goto end;
        }

        if (!of_property_read_u32(np, "st-plgpio,dir-reg", &val)) {
                plgpio->regs.dir = val;
        } else {
                dev_err(&pdev->dev, "DT: Invalid dir reg\n");
                goto end;
        }

        if (!of_property_read_u32(np, "st-plgpio,ie-reg", &val)) {
                plgpio->regs.ie = val;
        } else {
                dev_err(&pdev->dev, "DT: Invalid ie reg\n");
                goto end;
        }

        if (!of_property_read_u32(np, "st-plgpio,rdata-reg", &val)) {
                plgpio->regs.rdata = val;
        } else {
                dev_err(&pdev->dev, "DT: Invalid rdata reg\n");
                goto end;
        }

        if (!of_property_read_u32(np, "st-plgpio,mis-reg", &val)) {
                plgpio->regs.mis = val;
        } else {
                dev_err(&pdev->dev, "DT: Invalid mis reg\n");
                goto end;
        }

        if (!of_property_read_u32(np, "st-plgpio,eit-reg", &val))
                plgpio->regs.eit = val;
        else
                plgpio->regs.eit = -1;

        return 0;

end:
        return ret;
}
static int plgpio_probe(struct platform_device *pdev)
{
        struct plgpio *plgpio;
        struct resource *res;
        int ret, irq;

        plgpio = devm_kzalloc(&pdev->dev, sizeof(*plgpio), GFP_KERNEL);
        if (!plgpio)
                return -ENOMEM;

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        plgpio->base = devm_ioremap_resource(&pdev->dev, res);
        if (IS_ERR(plgpio->base))
                return PTR_ERR(plgpio->base);

        ret = plgpio_probe_dt(pdev, plgpio);
        if (ret) {
                dev_err(&pdev->dev, "DT probe failed\n");
                return ret;
        }

        plgpio->clk = devm_clk_get(&pdev->dev, NULL);
        if (IS_ERR(plgpio->clk))
                dev_warn(&pdev->dev, "clk_get() failed, work without it\n");

#ifdef CONFIG_PM_SLEEP
        plgpio->csave_regs = devm_kcalloc(&pdev->dev,
                        DIV_ROUND_UP(plgpio->chip.ngpio, MAX_GPIO_PER_REG),
                        sizeof(*plgpio->csave_regs),
                        GFP_KERNEL);
        if (!plgpio->csave_regs)
                return -ENOMEM;
#endif

        platform_set_drvdata(pdev, plgpio);
        spin_lock_init(&plgpio->lock);

        plgpio->chip.base = -1;
        plgpio->chip.request = plgpio_request;
        plgpio->chip.free = plgpio_free;
        plgpio->chip.direction_input = plgpio_direction_input;
        plgpio->chip.direction_output = plgpio_direction_output;
        plgpio->chip.get = plgpio_get_value;
        plgpio->chip.set = plgpio_set_value;
        plgpio->chip.label = dev_name(&pdev->dev);
        plgpio->chip.parent = &pdev->dev;
        plgpio->chip.owner = THIS_MODULE;
        plgpio->chip.of_node = pdev->dev.of_node;

        if (!IS_ERR(plgpio->clk)) {
                ret = clk_prepare(plgpio->clk);
                if (ret) {
                        dev_err(&pdev->dev, "clk prepare failed\n");
                        return ret;
                }
        }

        ret = gpiochip_add_data(&plgpio->chip, plgpio);
        if (ret) {
                dev_err(&pdev->dev, "unable to add gpio chip\n");
                goto unprepare_clk;
        }

        irq = platform_get_irq(pdev, 0);
        if (irq < 0) {
                dev_info(&pdev->dev, "PLGPIO registered without IRQs\n");
                return 0;
        }

        ret = gpiochip_irqchip_add(&plgpio->chip,
                                   &plgpio_irqchip,
                                   0,
                                   handle_simple_irq,
                                   IRQ_TYPE_NONE);
        if (ret) {
                dev_err(&pdev->dev, "failed to add irqchip to gpiochip\n");
                goto remove_gpiochip;
        }

        gpiochip_set_chained_irqchip(&plgpio->chip,
                                     &plgpio_irqchip,
                                     irq,
                                     plgpio_irq_handler);

        dev_info(&pdev->dev, "PLGPIO registered with IRQs\n");

        return 0;

remove_gpiochip:
        dev_info(&pdev->dev, "Remove gpiochip\n");
        gpiochip_remove(&plgpio->chip);
unprepare_clk:
        if (!IS_ERR(plgpio->clk))
                clk_unprepare(plgpio->clk);

        return ret;
}

#ifdef CONFIG_PM_SLEEP
static int plgpio_suspend(struct device *dev)
{
        struct plgpio *plgpio = dev_get_drvdata(dev);
        int i, reg_count = DIV_ROUND_UP(plgpio->chip.ngpio, MAX_GPIO_PER_REG);
        void __iomem *off;

        for (i = 0; i < reg_count; i++) {
                off = plgpio->base + i * sizeof(int *);

                if (plgpio->regs.enb != -1)
                        plgpio->csave_regs[i].enb =
                                readl_relaxed(plgpio->regs.enb + off);
                if (plgpio->regs.eit != -1)
                        plgpio->csave_regs[i].eit =
                                readl_relaxed(plgpio->regs.eit + off);
                plgpio->csave_regs[i].wdata = readl_relaxed(plgpio->regs.wdata +
                                off);
                plgpio->csave_regs[i].dir = readl_relaxed(plgpio->regs.dir +
                                off);
                plgpio->csave_regs[i].ie = readl_relaxed(plgpio->regs.ie + off);
        }

        return 0;
}

/*
 * This is used to correct the values in end registers. End registers contain
 * extra bits that might be used for other purpose in platform. So, we shouldn't
 * overwrite these bits. This macro, reads given register again, preserves other
 * bit values (non-plgpio bits), and retain captured value (plgpio bits).
 */
#define plgpio_prepare_reg(__reg, _off, _mask, _tmp)            \
{                                                               \
        _tmp = readl_relaxed(plgpio->regs.__reg + _off);                \
        _tmp &= ~_mask;                                         \
        plgpio->csave_regs[i].__reg =                           \
                _tmp | (plgpio->csave_regs[i].__reg & _mask);   \
}

static int plgpio_resume(struct device *dev)
{
        struct plgpio *plgpio = dev_get_drvdata(dev);
        int i, reg_count = DIV_ROUND_UP(plgpio->chip.ngpio, MAX_GPIO_PER_REG);
        void __iomem *off;
        u32 mask, tmp;

        for (i = 0; i < reg_count; i++) {
                off = plgpio->base + i * sizeof(int *);

                if (i == reg_count - 1) {
                        mask = (1 << (plgpio->chip.ngpio - i *
                                                MAX_GPIO_PER_REG)) - 1;

                        if (plgpio->regs.enb != -1)
                                plgpio_prepare_reg(enb, off, mask, tmp);

                        if (plgpio->regs.eit != -1)
                                plgpio_prepare_reg(eit, off, mask, tmp);

                        plgpio_prepare_reg(wdata, off, mask, tmp);
                        plgpio_prepare_reg(dir, off, mask, tmp);
                        plgpio_prepare_reg(ie, off, mask, tmp);
                }

                writel_relaxed(plgpio->csave_regs[i].wdata, plgpio->regs.wdata +
                                off);
                writel_relaxed(plgpio->csave_regs[i].dir, plgpio->regs.dir +
                                off);

                if (plgpio->regs.eit != -1)
                        writel_relaxed(plgpio->csave_regs[i].eit,
                                        plgpio->regs.eit + off);

                writel_relaxed(plgpio->csave_regs[i].ie, plgpio->regs.ie + off);

                if (plgpio->regs.enb != -1)
                        writel_relaxed(plgpio->csave_regs[i].enb,
                                        plgpio->regs.enb + off);
        }

        return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(plgpio_dev_pm_ops, plgpio_suspend, plgpio_resume);

static const struct of_device_id plgpio_of_match[] = {
        { .compatible = "st,spear-plgpio" },
        {}
};

static struct platform_driver plgpio_driver = {
        .probe = plgpio_probe,
        .driver = {
                .name = "spear-plgpio",
                .pm = &plgpio_dev_pm_ops,
                .of_match_table = plgpio_of_match,
        },
};

static int __init plgpio_init(void)
{
        return platform_driver_register(&plgpio_driver);
}
subsys_initcall(plgpio_init);