/*
 * QUICC Engine GPIOs
 *
 * Copyright (c) MontaVista Software, Inc. 2008.
 *
 * Author: Anton Vorontsov <avorontsov@ru.mvista.com>
 *
 * This program is free software; you can redistribute  it and/or modify it
 * under  the terms of  the GNU General  Public License as published by the
 * Free Software Foundation;  either version 2 of the  License, or (at your
 * option) any later version.
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/of_gpio.h>
#include <linux/gpio.h>
#include <linux/slab.h>
#include <asm/qe.h>

struct qe_gpio_chip {
        struct of_mm_gpio_chip mm_gc;
        spinlock_t lock;

        unsigned long pin_flags[QE_PIO_PINS];
#define QE_PIN_REQUESTED 0

        /* shadowed data register to clear/set bits safely */
        u32 cpdata;

        /* saved_regs used to restore dedicated functions */
        struct qe_pio_regs saved_regs;
};

static inline struct qe_gpio_chip *
to_qe_gpio_chip(struct of_mm_gpio_chip *mm_gc)
{
        return container_of(mm_gc, struct qe_gpio_chip, mm_gc);
}

static void qe_gpio_save_regs(struct of_mm_gpio_chip *mm_gc)
{
        struct qe_gpio_chip *qe_gc = to_qe_gpio_chip(mm_gc);
        struct qe_pio_regs __iomem *regs = mm_gc->regs;

        qe_gc->cpdata = in_be32(&regs->cpdata);
        qe_gc->saved_regs.cpdata = qe_gc->cpdata;
        qe_gc->saved_regs.cpdir1 = in_be32(&regs->cpdir1);
        qe_gc->saved_regs.cpdir2 = in_be32(&regs->cpdir2);
        qe_gc->saved_regs.cppar1 = in_be32(&regs->cppar1);
        qe_gc->saved_regs.cppar2 = in_be32(&regs->cppar2);
        qe_gc->saved_regs.cpodr = in_be32(&regs->cpodr);
}

static int qe_gpio_get(struct gpio_chip *gc, unsigned int gpio)
{
        struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
        struct qe_pio_regs __iomem *regs = mm_gc->regs;
        u32 pin_mask = 1 << (QE_PIO_PINS - 1 - gpio);

        return in_be32(&regs->cpdata) & pin_mask;
}

static void qe_gpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
{
        struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
        struct qe_gpio_chip *qe_gc = to_qe_gpio_chip(mm_gc);
        struct qe_pio_regs __iomem *regs = mm_gc->regs;
        unsigned long flags;
        u32 pin_mask = 1 << (QE_PIO_PINS - 1 - gpio);

        spin_lock_irqsave(&qe_gc->lock, flags);

        if (val)
                qe_gc->cpdata |= pin_mask;
        else
                qe_gc->cpdata &= ~pin_mask;

        out_be32(&regs->cpdata, qe_gc->cpdata);

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

static int qe_gpio_dir_in(struct gpio_chip *gc, unsigned int gpio)
{
        struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
        struct qe_gpio_chip *qe_gc = to_qe_gpio_chip(mm_gc);
        unsigned long flags;

        spin_lock_irqsave(&qe_gc->lock, flags);

        __par_io_config_pin(mm_gc->regs, gpio, QE_PIO_DIR_IN, 0, 0, 0);

        spin_unlock_irqrestore(&qe_gc->lock, flags);

        return 0;
}

static int qe_gpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
{
        struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
        struct qe_gpio_chip *qe_gc = to_qe_gpio_chip(mm_gc);
        unsigned long flags;

        qe_gpio_set(gc, gpio, val);

        spin_lock_irqsave(&qe_gc->lock, flags);

        __par_io_config_pin(mm_gc->regs, gpio, QE_PIO_DIR_OUT, 0, 0, 0);

        spin_unlock_irqrestore(&qe_gc->lock, flags);

        return 0;
}

struct qe_pin {
        /*
         * The qe_gpio_chip name is unfortunate, we should change that to
         * something like qe_pio_controller. Someday.
         */
        struct qe_gpio_chip *controller;
        int num;
};

/**
 * qe_pin_request - Request a QE pin
 * @np:         device node to get a pin from
 * @index:      index of a pin in the device tree
 * Context:     non-atomic
 *
 * This function return qe_pin so that you could use it with the rest of
 * the QE Pin Multiplexing API.
 */
struct qe_pin *qe_pin_request(struct device_node *np, int index)
{
        struct qe_pin *qe_pin;
        struct device_node *gpio_np;
        struct gpio_chip *gc;
        struct of_mm_gpio_chip *mm_gc;
        struct qe_gpio_chip *qe_gc;
        int err;
        int size;
        const void *gpio_spec;
        const u32 *gpio_cells;
        unsigned long flags;

        qe_pin = kzalloc(sizeof(*qe_pin), GFP_KERNEL);
        if (!qe_pin) {
                pr_debug("%s: can't allocate memory\n", __func__);
                return ERR_PTR(-ENOMEM);
        }

        err = of_parse_phandles_with_args(np, "gpios", "#gpio-cells", index,
                                          &gpio_np, &gpio_spec);
        if (err) {
                pr_debug("%s: can't parse gpios property\n", __func__);
                goto err0;
        }

        if (!of_device_is_compatible(gpio_np, "fsl,mpc8323-qe-pario-bank")) {
                pr_debug("%s: tried to get a non-qe pin\n", __func__);
                err = -EINVAL;
                goto err1;
        }

        gc = of_node_to_gpiochip(gpio_np);
        if (!gc) {
                pr_debug("%s: gpio controller %s isn't registered\n",
                         np->full_name, gpio_np->full_name);
                err = -ENODEV;
                goto err1;
        }

        gpio_cells = of_get_property(gpio_np, "#gpio-cells", &size);
        if (!gpio_cells || size != sizeof(*gpio_cells) ||
                        *gpio_cells != gc->of_gpio_n_cells) {
                pr_debug("%s: wrong #gpio-cells for %s\n",
                         np->full_name, gpio_np->full_name);
                err = -EINVAL;
                goto err1;
        }

        err = gc->of_xlate(gc, np, gpio_spec, NULL);
        if (err < 0)
                goto err1;

        mm_gc = to_of_mm_gpio_chip(gc);
        qe_gc = to_qe_gpio_chip(mm_gc);

        spin_lock_irqsave(&qe_gc->lock, flags);

        if (test_and_set_bit(QE_PIN_REQUESTED, &qe_gc->pin_flags[err]) == 0) {
                qe_pin->controller = qe_gc;
                qe_pin->num = err;
                err = 0;
        } else {
                err = -EBUSY;
        }

        spin_unlock_irqrestore(&qe_gc->lock, flags);

        if (!err)
                return qe_pin;
err1:
        of_node_put(gpio_np);
err0:
        kfree(qe_pin);
        pr_debug("%s failed with status %d\n", __func__, err);
        return ERR_PTR(err);
}
EXPORT_SYMBOL(qe_pin_request);

/**
 * qe_pin_free - Free a pin
 * @qe_pin:     pointer to the qe_pin structure
 * Context:     any
 *
 * This function frees the qe_pin structure and makes a pin available
 * for further qe_pin_request() calls.
 */
void qe_pin_free(struct qe_pin *qe_pin)
{
        struct qe_gpio_chip *qe_gc = qe_pin->controller;
        unsigned long flags;
        const int pin = qe_pin->num;

        spin_lock_irqsave(&qe_gc->lock, flags);
        test_and_clear_bit(QE_PIN_REQUESTED, &qe_gc->pin_flags[pin]);
        spin_unlock_irqrestore(&qe_gc->lock, flags);

        kfree(qe_pin);
}
EXPORT_SYMBOL(qe_pin_free);

/**
 * qe_pin_set_dedicated - Revert a pin to a dedicated peripheral function mode
 * @qe_pin:     pointer to the qe_pin structure
 * Context:     any
 *
 * This function resets a pin to a dedicated peripheral function that
 * has been set up by the firmware.
 */
void qe_pin_set_dedicated(struct qe_pin *qe_pin)
{
        struct qe_gpio_chip *qe_gc = qe_pin->controller;
        struct qe_pio_regs __iomem *regs = qe_gc->mm_gc.regs;
        struct qe_pio_regs *sregs = &qe_gc->saved_regs;
        int pin = qe_pin->num;
        u32 mask1 = 1 << (QE_PIO_PINS - (pin + 1));
        u32 mask2 = 0x3 << (QE_PIO_PINS - (pin % (QE_PIO_PINS / 2) + 1) * 2);
        bool second_reg = pin > (QE_PIO_PINS / 2) - 1;
        unsigned long flags;

        spin_lock_irqsave(&qe_gc->lock, flags);

        if (second_reg) {
                clrsetbits_be32(&regs->cpdir2, mask2, sregs->cpdir2 & mask2);
                clrsetbits_be32(&regs->cppar2, mask2, sregs->cppar2 & mask2);
        } else {
                clrsetbits_be32(&regs->cpdir1, mask2, sregs->cpdir1 & mask2);
                clrsetbits_be32(&regs->cppar1, mask2, sregs->cppar1 & mask2);
        }

        if (sregs->cpdata & mask1)
                qe_gc->cpdata |= mask1;
        else
                qe_gc->cpdata &= ~mask1;

        out_be32(&regs->cpdata, qe_gc->cpdata);
        clrsetbits_be32(&regs->cpodr, mask1, sregs->cpodr & mask1);

        spin_unlock_irqrestore(&qe_gc->lock, flags);
}
EXPORT_SYMBOL(qe_pin_set_dedicated);

/**
 * qe_pin_set_gpio - Set a pin to the GPIO mode
 * @qe_pin:     pointer to the qe_pin structure
 * Context:     any
 *
 * This function sets a pin to the GPIO mode.
 */
void qe_pin_set_gpio(struct qe_pin *qe_pin)
{
        struct qe_gpio_chip *qe_gc = qe_pin->controller;
        struct qe_pio_regs __iomem *regs = qe_gc->mm_gc.regs;
        unsigned long flags;

        spin_lock_irqsave(&qe_gc->lock, flags);

        /* Let's make it input by default, GPIO API is able to change that. */
        __par_io_config_pin(regs, qe_pin->num, QE_PIO_DIR_IN, 0, 0, 0);

        spin_unlock_irqrestore(&qe_gc->lock, flags);
}
EXPORT_SYMBOL(qe_pin_set_gpio);

static int __init qe_add_gpiochips(void)
{
        struct device_node *np;

        for_each_compatible_node(np, NULL, "fsl,mpc8323-qe-pario-bank") {
                int ret;
                struct qe_gpio_chip *qe_gc;
                struct of_mm_gpio_chip *mm_gc;
                struct gpio_chip *gc;

                qe_gc = kzalloc(sizeof(*qe_gc), GFP_KERNEL);
                if (!qe_gc) {
                        ret = -ENOMEM;
                        goto err;
                }

                spin_lock_init(&qe_gc->lock);

                mm_gc = &qe_gc->mm_gc;
                gc = &mm_gc->gc;

                mm_gc->save_regs = qe_gpio_save_regs;
                gc->ngpio = QE_PIO_PINS;
                gc->direction_input = qe_gpio_dir_in;
                gc->direction_output = qe_gpio_dir_out;
                gc->get = qe_gpio_get;
                gc->set = qe_gpio_set;

                ret = of_mm_gpiochip_add(np, mm_gc);
                if (ret)
                        goto err;
                continue;
err:
                pr_err("%s: registration failed with status %d\n",
                       np->full_name, ret);
                kfree(qe_gc);
                /* try others anyway */
        }
        return 0;
}
arch_initcall(qe_add_gpiochips);