/*
 * External Interrupt Controller on Spider South Bridge
 *
 * (C) Copyright IBM Deutschland Entwicklung GmbH 2005
 *
 * Author: Arnd Bergmann <arndb@de.ibm.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, or (at your option)
 * any later version.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/ioport.h>

#include <asm/pgtable.h>
#include <asm/prom.h>
#include <asm/io.h>

#include "interrupt.h"

/* register layout taken from Spider spec, table 7.4-4 */
enum {
        TIR_DEN         = 0x004, /* Detection Enable Register */
        TIR_MSK         = 0x084, /* Mask Level Register */
        TIR_EDC         = 0x0c0, /* Edge Detection Clear Register */
        TIR_PNDA        = 0x100, /* Pending Register A */
        TIR_PNDB        = 0x104, /* Pending Register B */
        TIR_CS          = 0x144, /* Current Status Register */
        TIR_LCSA        = 0x150, /* Level Current Status Register A */
        TIR_LCSB        = 0x154, /* Level Current Status Register B */
        TIR_LCSC        = 0x158, /* Level Current Status Register C */
        TIR_LCSD        = 0x15c, /* Level Current Status Register D */
        TIR_CFGA        = 0x200, /* Setting Register A0 */
        TIR_CFGB        = 0x204, /* Setting Register B0 */
                        /* 0x208 ... 0x3ff Setting Register An/Bn */
        TIR_PPNDA       = 0x400, /* Packet Pending Register A */
        TIR_PPNDB       = 0x404, /* Packet Pending Register B */
        TIR_PIERA       = 0x408, /* Packet Output Error Register A */
        TIR_PIERB       = 0x40c, /* Packet Output Error Register B */
        TIR_PIEN        = 0x444, /* Packet Output Enable Register */
        TIR_PIPND       = 0x454, /* Packet Output Pending Register */
        TIRDID          = 0x484, /* Spider Device ID Register */
        REISTIM         = 0x500, /* Reissue Command Timeout Time Setting */
        REISTIMEN       = 0x504, /* Reissue Command Timeout Setting */
        REISWAITEN      = 0x508, /* Reissue Wait Control*/
};

#define SPIDER_CHIP_COUNT       4
#define SPIDER_SRC_COUNT        64
#define SPIDER_IRQ_INVALID      63

struct spider_pic {
        struct irq_domain               *host;
        void __iomem            *regs;
        unsigned int            node_id;
};
static struct spider_pic spider_pics[SPIDER_CHIP_COUNT];

static struct spider_pic *spider_irq_data_to_pic(struct irq_data *d)
{
        return irq_data_get_irq_chip_data(d);
}

static void __iomem *spider_get_irq_config(struct spider_pic *pic,
                                           unsigned int src)
{
        return pic->regs + TIR_CFGA + 8 * src;
}

static void spider_unmask_irq(struct irq_data *d)
{
        struct spider_pic *pic = spider_irq_data_to_pic(d);
        void __iomem *cfg = spider_get_irq_config(pic, irqd_to_hwirq(d));

        out_be32(cfg, in_be32(cfg) | 0x30000000u);
}

static void spider_mask_irq(struct irq_data *d)
{
        struct spider_pic *pic = spider_irq_data_to_pic(d);
        void __iomem *cfg = spider_get_irq_config(pic, irqd_to_hwirq(d));

        out_be32(cfg, in_be32(cfg) & ~0x30000000u);
}

static void spider_ack_irq(struct irq_data *d)
{
        struct spider_pic *pic = spider_irq_data_to_pic(d);
        unsigned int src = irqd_to_hwirq(d);

        /* Reset edge detection logic if necessary
         */
        if (irqd_is_level_type(d))
                return;

        /* Only interrupts 47 to 50 can be set to edge */
        if (src < 47 || src > 50)
                return;

        /* Perform the clear of the edge logic */
        out_be32(pic->regs + TIR_EDC, 0x100 | (src & 0xf));
}

static int spider_set_irq_type(struct irq_data *d, unsigned int type)
{
        unsigned int sense = type & IRQ_TYPE_SENSE_MASK;
        struct spider_pic *pic = spider_irq_data_to_pic(d);
        unsigned int hw = irqd_to_hwirq(d);
        void __iomem *cfg = spider_get_irq_config(pic, hw);
        u32 old_mask;
        u32 ic;

        /* Note that only level high is supported for most interrupts */
        if (sense != IRQ_TYPE_NONE && sense != IRQ_TYPE_LEVEL_HIGH &&
            (hw < 47 || hw > 50))
                return -EINVAL;

        /* Decode sense type */
        switch(sense) {
        case IRQ_TYPE_EDGE_RISING:
                ic = 0x3;
                break;
        case IRQ_TYPE_EDGE_FALLING:
                ic = 0x2;
                break;
        case IRQ_TYPE_LEVEL_LOW:
                ic = 0x0;
                break;
        case IRQ_TYPE_LEVEL_HIGH:
        case IRQ_TYPE_NONE:
                ic = 0x1;
                break;
        default:
                return -EINVAL;
        }

        /* Configure the source. One gross hack that was there before and
         * that I've kept around is the priority to the BE which I set to
         * be the same as the interrupt source number. I don't know whether
         * that's supposed to make any kind of sense however, we'll have to
         * decide that, but for now, I'm not changing the behaviour.
         */
        old_mask = in_be32(cfg) & 0x30000000u;
        out_be32(cfg, old_mask | (ic << 24) | (0x7 << 16) |
                 (pic->node_id << 4) | 0xe);
        out_be32(cfg + 4, (0x2 << 16) | (hw & 0xff));

        return 0;
}

static struct irq_chip spider_pic = {
        .name = "SPIDER",
        .irq_unmask = spider_unmask_irq,
        .irq_mask = spider_mask_irq,
        .irq_ack = spider_ack_irq,
        .irq_set_type = spider_set_irq_type,
};

static int spider_host_map(struct irq_domain *h, unsigned int virq,
                        irq_hw_number_t hw)
{
        irq_set_chip_data(virq, h->host_data);
        irq_set_chip_and_handler(virq, &spider_pic, handle_level_irq);

        /* Set default irq type */
        irq_set_irq_type(virq, IRQ_TYPE_NONE);

        return 0;
}

static int spider_host_xlate(struct irq_domain *h, struct device_node *ct,
                           const u32 *intspec, unsigned int intsize,
                           irq_hw_number_t *out_hwirq, unsigned int *out_flags)

{
        /* Spider interrupts have 2 cells, first is the interrupt source,
         * second, well, I don't know for sure yet ... We mask the top bits
         * because old device-trees encode a node number in there
         */
        *out_hwirq = intspec[0] & 0x3f;
        *out_flags = IRQ_TYPE_LEVEL_HIGH;
        return 0;
}

static const struct irq_domain_ops spider_host_ops = {
        .map = spider_host_map,
        .xlate = spider_host_xlate,
};

static void spider_irq_cascade(unsigned int irq, struct irq_desc *desc)
{
        struct irq_chip *chip = irq_desc_get_chip(desc);
        struct spider_pic *pic = irq_desc_get_handler_data(desc);
        unsigned int cs, virq;

        cs = in_be32(pic->regs + TIR_CS) >> 24;
        if (cs == SPIDER_IRQ_INVALID)
                virq = NO_IRQ;
        else
                virq = irq_linear_revmap(pic->host, cs);

        if (virq != NO_IRQ)
                generic_handle_irq(virq);

        chip->irq_eoi(&desc->irq_data);
}

/* For hooking up the cascace we have a problem. Our device-tree is
 * crap and we don't know on which BE iic interrupt we are hooked on at
 * least not the "standard" way. We can reconstitute it based on two
 * informations though: which BE node we are connected to and whether
 * we are connected to IOIF0 or IOIF1. Right now, we really only care
 * about the IBM cell blade and we know that its firmware gives us an
 * interrupt-map property which is pretty strange.
 */
static unsigned int __init spider_find_cascade_and_node(struct spider_pic *pic)
{
        unsigned int virq;
        const u32 *imap, *tmp;
        int imaplen, intsize, unit;
        struct device_node *iic;

        /* First, we check whether we have a real "interrupts" in the device
         * tree in case the device-tree is ever fixed
         */
        struct of_irq oirq;
        if (of_irq_map_one(pic->host->of_node, 0, &oirq) == 0) {
                virq = irq_create_of_mapping(oirq.controller, oirq.specifier,
                                             oirq.size);
                return virq;
        }

        /* Now do the horrible hacks */
        tmp = of_get_property(pic->host->of_node, "#interrupt-cells", NULL);
        if (tmp == NULL)
                return NO_IRQ;
        intsize = *tmp;
        imap = of_get_property(pic->host->of_node, "interrupt-map", &imaplen);
        if (imap == NULL || imaplen < (intsize + 1))
                return NO_IRQ;
        iic = of_find_node_by_phandle(imap[intsize]);
        if (iic == NULL)
                return NO_IRQ;
        imap += intsize + 1;
        tmp = of_get_property(iic, "#interrupt-cells", NULL);
        if (tmp == NULL) {
                of_node_put(iic);
                return NO_IRQ;
        }
        intsize = *tmp;
        /* Assume unit is last entry of interrupt specifier */
        unit = imap[intsize - 1];
        /* Ok, we have a unit, now let's try to get the node */
        tmp = of_get_property(iic, "ibm,interrupt-server-ranges", NULL);
        if (tmp == NULL) {
                of_node_put(iic);
                return NO_IRQ;
        }
        /* ugly as hell but works for now */
        pic->node_id = (*tmp) >> 1;
        of_node_put(iic);

        /* Ok, now let's get cracking. You may ask me why I just didn't match
         * the iic host from the iic OF node, but that way I'm still compatible
         * with really really old old firmwares for which we don't have a node
         */
        /* Manufacture an IIC interrupt number of class 2 */
        virq = irq_create_mapping(NULL,
                                  (pic->node_id << IIC_IRQ_NODE_SHIFT) |
                                  (2 << IIC_IRQ_CLASS_SHIFT) |
                                  unit);
        if (virq == NO_IRQ)
                printk(KERN_ERR "spider_pic: failed to map cascade !");
        return virq;
}


static void __init spider_init_one(struct device_node *of_node, int chip,
                                   unsigned long addr)
{
        struct spider_pic *pic = &spider_pics[chip];
        int i, virq;

        /* Map registers */
        pic->regs = ioremap(addr, 0x1000);
        if (pic->regs == NULL)
                panic("spider_pic: can't map registers !");

        /* Allocate a host */
        pic->host = irq_domain_add_linear(of_node, SPIDER_SRC_COUNT,
                                          &spider_host_ops, pic);
        if (pic->host == NULL)
                panic("spider_pic: can't allocate irq host !");

        /* Go through all sources and disable them */
        for (i = 0; i < SPIDER_SRC_COUNT; i++) {
                void __iomem *cfg = pic->regs + TIR_CFGA + 8 * i;
                out_be32(cfg, in_be32(cfg) & ~0x30000000u);
        }

        /* do not mask any interrupts because of level */
        out_be32(pic->regs + TIR_MSK, 0x0);

        /* enable interrupt packets to be output */
        out_be32(pic->regs + TIR_PIEN, in_be32(pic->regs + TIR_PIEN) | 0x1);

        /* Hook up the cascade interrupt to the iic and nodeid */
        virq = spider_find_cascade_and_node(pic);
        if (virq == NO_IRQ)
                return;
        irq_set_handler_data(virq, pic);
        irq_set_chained_handler(virq, spider_irq_cascade);

        printk(KERN_INFO "spider_pic: node %d, addr: 0x%lx %s\n",
               pic->node_id, addr, of_node->full_name);

        /* Enable the interrupt detection enable bit. Do this last! */
        out_be32(pic->regs + TIR_DEN, in_be32(pic->regs + TIR_DEN) | 0x1);
}

void __init spider_init_IRQ(void)
{
        struct resource r;
        struct device_node *dn;
        int chip = 0;

        /* XXX node numbers are totally bogus. We _hope_ we get the device
         * nodes in the right order here but that's definitely not guaranteed,
         * we need to get the node from the device tree instead.
         * There is currently no proper property for it (but our whole
         * device-tree is bogus anyway) so all we can do is pray or maybe test
         * the address and deduce the node-id
         */
        for (dn = NULL;
             (dn = of_find_node_by_name(dn, "interrupt-controller"));) {
                if (of_device_is_compatible(dn, "CBEA,platform-spider-pic")) {
                        if (of_address_to_resource(dn, 0, &r)) {
                                printk(KERN_WARNING "spider-pic: Failed\n");
                                continue;
                        }
                } else if (of_device_is_compatible(dn, "sti,platform-spider-pic")
                           && (chip < 2)) {
                        static long hard_coded_pics[] =
                                { 0x24000008000ul, 0x34000008000ul};
                        r.start = hard_coded_pics[chip];
                } else
                        continue;
                spider_init_one(dn, chip++, r.start);
        }
}