/*
 * Copyright 2011-2012, Meador Inge, Mentor Graphics Corporation.
 *
 * Some ideas based on un-pushed work done by Vivek Mahajan, Jason Jin, and
 * Mingkai Hu from Freescale Semiconductor, Inc.
 *
 * 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; version 2 of the
 * License.
 *
 */

#include <linux/list.h>
#include <linux/of_platform.h>
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <asm/prom.h>
#include <asm/hw_irq.h>
#include <asm/ppc-pci.h>
#include <asm/mpic_msgr.h>

#define MPIC_MSGR_REGISTERS_PER_BLOCK   4
#define MPIC_MSGR_STRIDE                0x10
#define MPIC_MSGR_MER_OFFSET            0x100
#define MSGR_INUSE                      0
#define MSGR_FREE                       1

static struct mpic_msgr **mpic_msgrs;
static unsigned int mpic_msgr_count;
static DEFINE_RAW_SPINLOCK(msgrs_lock);

static inline void _mpic_msgr_mer_write(struct mpic_msgr *msgr, u32 value)
{
        out_be32(msgr->mer, value);
}

static inline u32 _mpic_msgr_mer_read(struct mpic_msgr *msgr)
{
        return in_be32(msgr->mer);
}

static inline void _mpic_msgr_disable(struct mpic_msgr *msgr)
{
        u32 mer = _mpic_msgr_mer_read(msgr);

        _mpic_msgr_mer_write(msgr, mer & ~(1 << msgr->num));
}

struct mpic_msgr *mpic_msgr_get(unsigned int reg_num)
{
        unsigned long flags;
        struct mpic_msgr *msgr;

        /* Assume busy until proven otherwise.  */
        msgr = ERR_PTR(-EBUSY);

        if (reg_num >= mpic_msgr_count)
                return ERR_PTR(-ENODEV);

        raw_spin_lock_irqsave(&msgrs_lock, flags);
        msgr = mpic_msgrs[reg_num];
        if (msgr->in_use == MSGR_FREE)
                msgr->in_use = MSGR_INUSE;
        raw_spin_unlock_irqrestore(&msgrs_lock, flags);

        return msgr;
}
EXPORT_SYMBOL_GPL(mpic_msgr_get);

void mpic_msgr_put(struct mpic_msgr *msgr)
{
        unsigned long flags;

        raw_spin_lock_irqsave(&msgr->lock, flags);
        msgr->in_use = MSGR_FREE;
        _mpic_msgr_disable(msgr);
        raw_spin_unlock_irqrestore(&msgr->lock, flags);
}
EXPORT_SYMBOL_GPL(mpic_msgr_put);

void mpic_msgr_enable(struct mpic_msgr *msgr)
{
        unsigned long flags;
        u32 mer;

        raw_spin_lock_irqsave(&msgr->lock, flags);
        mer = _mpic_msgr_mer_read(msgr);
        _mpic_msgr_mer_write(msgr, mer | (1 << msgr->num));
        raw_spin_unlock_irqrestore(&msgr->lock, flags);
}
EXPORT_SYMBOL_GPL(mpic_msgr_enable);

void mpic_msgr_disable(struct mpic_msgr *msgr)
{
        unsigned long flags;

        raw_spin_lock_irqsave(&msgr->lock, flags);
        _mpic_msgr_disable(msgr);
        raw_spin_unlock_irqrestore(&msgr->lock, flags);
}
EXPORT_SYMBOL_GPL(mpic_msgr_disable);

/* The following three functions are used to compute the order and number of
 * the message register blocks.  They are clearly very inefficent.  However,
 * they are called *only* a few times during device initialization.
 */
static unsigned int mpic_msgr_number_of_blocks(void)
{
        unsigned int count;
        struct device_node *aliases;

        count = 0;
        aliases = of_find_node_by_name(NULL, "aliases");

        if (aliases) {
                char buf[32];

                for (;;) {
                        snprintf(buf, sizeof(buf), "mpic-msgr-block%d", count);
                        if (!of_find_property(aliases, buf, NULL))
                                break;

                        count += 1;
                }
        }

        return count;
}

static unsigned int mpic_msgr_number_of_registers(void)
{
        return mpic_msgr_number_of_blocks() * MPIC_MSGR_REGISTERS_PER_BLOCK;
}

static int mpic_msgr_block_number(struct device_node *node)
{
        struct device_node *aliases;
        unsigned int index, number_of_blocks;
        char buf[64];

        number_of_blocks = mpic_msgr_number_of_blocks();
        aliases = of_find_node_by_name(NULL, "aliases");
        if (!aliases)
                return -1;

        for (index = 0; index < number_of_blocks; ++index) {
                struct property *prop;

                snprintf(buf, sizeof(buf), "mpic-msgr-block%d", index);
                prop = of_find_property(aliases, buf, NULL);
                if (node == of_find_node_by_path(prop->value))
                        break;
        }

        return index == number_of_blocks ? -1 : index;
}

/* The probe function for a single message register block.
 */
static int mpic_msgr_probe(struct platform_device *dev)
{
        void __iomem *msgr_block_addr;
        int block_number;
        struct resource rsrc;
        unsigned int i;
        unsigned int irq_index;
        struct device_node *np = dev->dev.of_node;
        unsigned int receive_mask;
        const unsigned int *prop;

        if (!np) {
                dev_err(&dev->dev, "Device OF-Node is NULL");
                return -EFAULT;
        }

        /* Allocate the message register array upon the first device
         * registered.
         */
        if (!mpic_msgrs) {
                mpic_msgr_count = mpic_msgr_number_of_registers();
                dev_info(&dev->dev, "Found %d message registers\n",
                                mpic_msgr_count);

                mpic_msgrs = kcalloc(mpic_msgr_count, sizeof(*mpic_msgrs),
                                                         GFP_KERNEL);
                if (!mpic_msgrs) {
                        dev_err(&dev->dev,
                                "No memory for message register blocks\n");
                        return -ENOMEM;
                }
        }
        dev_info(&dev->dev, "Of-device full name %s\n", np->full_name);

        /* IO map the message register block. */
        of_address_to_resource(np, 0, &rsrc);
        msgr_block_addr = ioremap(rsrc.start, rsrc.end - rsrc.start);
        if (!msgr_block_addr) {
                dev_err(&dev->dev, "Failed to iomap MPIC message registers");
                return -EFAULT;
        }

        /* Ensure the block has a defined order. */
        block_number = mpic_msgr_block_number(np);
        if (block_number < 0) {
                dev_err(&dev->dev,
                        "Failed to find message register block alias\n");
                return -ENODEV;
        }
        dev_info(&dev->dev, "Setting up message register block %d\n",
                        block_number);

        /* Grab the receive mask which specifies what registers can receive
         * interrupts.
         */
        prop = of_get_property(np, "mpic-msgr-receive-mask", NULL);
        receive_mask = (prop) ? *prop : 0xF;

        /* Build up the appropriate message register data structures. */
        for (i = 0, irq_index = 0; i < MPIC_MSGR_REGISTERS_PER_BLOCK; ++i) {
                struct mpic_msgr *msgr;
                unsigned int reg_number;

                msgr = kzalloc(sizeof(struct mpic_msgr), GFP_KERNEL);
                if (!msgr) {
                        dev_err(&dev->dev, "No memory for message register\n");
                        return -ENOMEM;
                }

                reg_number = block_number * MPIC_MSGR_REGISTERS_PER_BLOCK + i;
                msgr->base = msgr_block_addr + i * MPIC_MSGR_STRIDE;
                msgr->mer = (u32 *)((u8 *)msgr->base + MPIC_MSGR_MER_OFFSET);
                msgr->in_use = MSGR_FREE;
                msgr->num = i;
                raw_spin_lock_init(&msgr->lock);

                if (receive_mask & (1 << i)) {
                        msgr->irq = irq_of_parse_and_map(np, irq_index);
                        if (msgr->irq == NO_IRQ) {
                                dev_err(&dev->dev,
                                                "Missing interrupt specifier");
                                kfree(msgr);
                                return -EFAULT;
                        }
                        irq_index += 1;
                } else {
                        msgr->irq = NO_IRQ;
                }

                mpic_msgrs[reg_number] = msgr;
                mpic_msgr_disable(msgr);
                dev_info(&dev->dev, "Register %d initialized: irq %d\n",
                                reg_number, msgr->irq);

        }

        return 0;
}

static const struct of_device_id mpic_msgr_ids[] = {
        {
                .compatible = "fsl,mpic-v3.1-msgr",
                .data = NULL,
        },
        {}
};

static struct platform_driver mpic_msgr_driver = {
        .driver = {
                .name = "mpic-msgr",
                .of_match_table = mpic_msgr_ids,
        },
        .probe = mpic_msgr_probe,
};

static __init int mpic_msgr_init(void)
{
        return platform_driver_register(&mpic_msgr_driver);
}
subsys_initcall(mpic_msgr_init);