/* -*- mode: c; c-basic-offset: 8 -*- */

/*
 * MCA bus support functions for legacy (2.4) API.
 *
 * Legacy API means the API that operates in terms of MCA slot number
 *
 * (C) 2002 James Bottomley <James.Bottomley@HansenPartnership.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.
**
**  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/module.h>
#include <linux/device.h>
#include <linux/mca-legacy.h>
#include <asm/io.h>

/* NOTE: This structure is stack allocated */
struct mca_find_adapter_info {
        int                     id;
        int                     slot;
        struct mca_device       *mca_dev;
};

/* The purpose of this iterator is to loop over all the devices and
 * find the one with the smallest slot number that's just greater than
 * or equal to the required slot with a matching id */
static int mca_find_adapter_callback(struct device *dev, void *data)
{
        struct mca_find_adapter_info *info = data;
        struct mca_device *mca_dev = to_mca_device(dev);

        if(mca_dev->pos_id != info->id)
                return 0;

        if(mca_dev->slot < info->slot)
                return 0;

        if(!info->mca_dev || info->mca_dev->slot >= mca_dev->slot)
                info->mca_dev = mca_dev;

        return 0;
}

/**
 *      mca_find_adapter - scan for adapters
 *      @id:    MCA identification to search for
 *      @start: starting slot
 *
 *      Search the MCA configuration for adapters matching the 16bit
 *      ID given. The first time it should be called with start as zero
 *      and then further calls made passing the return value of the
 *      previous call until %MCA_NOTFOUND is returned.
 *
 *      Disabled adapters are not reported.
 */

int mca_find_adapter(int id, int start)
{
        struct mca_find_adapter_info info;

        if(id == 0xffff)
                return MCA_NOTFOUND;

        info.slot = start;
        info.id = id;
        info.mca_dev = NULL;

        for(;;) {
                bus_for_each_dev(&mca_bus_type, NULL, &info, mca_find_adapter_callback);

                if(info.mca_dev == NULL)
                        return MCA_NOTFOUND;

                if(info.mca_dev->status != MCA_ADAPTER_DISABLED)
                        break;

                /* OK, found adapter but it was disabled.  Go around
                 * again, excluding the slot we just found */

                info.slot = info.mca_dev->slot + 1;
                info.mca_dev = NULL;
        }
                
        return info.mca_dev->slot;
}
EXPORT_SYMBOL(mca_find_adapter);

/*--------------------------------------------------------------------*/

/**
 *      mca_find_unused_adapter - scan for unused adapters
 *      @id:    MCA identification to search for
 *      @start: starting slot
 *
 *      Search the MCA configuration for adapters matching the 16bit
 *      ID given. The first time it should be called with start as zero
 *      and then further calls made passing the return value of the
 *      previous call until %MCA_NOTFOUND is returned.
 *
 *      Adapters that have been claimed by drivers and those that
 *      are disabled are not reported. This function thus allows a driver
 *      to scan for further cards when some may already be driven.
 */

int mca_find_unused_adapter(int id, int start)
{
        struct mca_find_adapter_info info = { 0 };

        if (!MCA_bus || id == 0xffff)
                return MCA_NOTFOUND;

        info.slot = start;
        info.id = id;
        info.mca_dev = NULL;

        for(;;) {
                bus_for_each_dev(&mca_bus_type, NULL, &info, mca_find_adapter_callback);

                if(info.mca_dev == NULL)
                        return MCA_NOTFOUND;

                if(info.mca_dev->status != MCA_ADAPTER_DISABLED
                   && !info.mca_dev->driver_loaded)
                        break;

                /* OK, found adapter but it was disabled or already in
                 * use.  Go around again, excluding the slot we just
                 * found */

                info.slot = info.mca_dev->slot + 1;
                info.mca_dev = NULL;
        }
                
        return info.mca_dev->slot;
}
EXPORT_SYMBOL(mca_find_unused_adapter);

/* NOTE: stack allocated structure */
struct mca_find_device_by_slot_info {
        int                     slot;
        struct mca_device       *mca_dev;
};

static int mca_find_device_by_slot_callback(struct device *dev, void *data)
{
        struct mca_find_device_by_slot_info *info = data;
        struct mca_device *mca_dev = to_mca_device(dev);

        if(mca_dev->slot == info->slot)
                info->mca_dev = mca_dev;

        return 0;
}

struct mca_device *mca_find_device_by_slot(int slot)
{
        struct mca_find_device_by_slot_info info;

        info.slot = slot;
        info.mca_dev = NULL;

        bus_for_each_dev(&mca_bus_type, NULL, &info, mca_find_device_by_slot_callback);

        return info.mca_dev;
}

/**
 *      mca_read_stored_pos - read POS register from boot data
 *      @slot: slot number to read from
 *      @reg:  register to read from
 *
 *      Fetch a POS value that was stored at boot time by the kernel
 *      when it scanned the MCA space. The register value is returned.
 *      Missing or invalid registers report 0.
 */
unsigned char mca_read_stored_pos(int slot, int reg)
{
        struct mca_device *mca_dev = mca_find_device_by_slot(slot);

        if(!mca_dev)
                return 0;

        return mca_device_read_stored_pos(mca_dev, reg);
}
EXPORT_SYMBOL(mca_read_stored_pos);


/**
 *      mca_read_pos - read POS register from card
 *      @slot: slot number to read from
 *      @reg:  register to read from
 *
 *      Fetch a POS value directly from the hardware to obtain the
 *      current value. This is much slower than mca_read_stored_pos and
 *      may not be invoked from interrupt context. It handles the
 *      deep magic required for onboard devices transparently.
 */

unsigned char mca_read_pos(int slot, int reg)
{
        struct mca_device *mca_dev = mca_find_device_by_slot(slot);

        if(!mca_dev)
                return 0;

        return mca_device_read_pos(mca_dev, reg);
}
EXPORT_SYMBOL(mca_read_pos);

                
/**
 *      mca_write_pos - read POS register from card
 *      @slot: slot number to read from
 *      @reg:  register to read from
 *      @byte: byte to write to the POS registers
 *
 *      Store a POS value directly from the hardware. You should not
 *      normally need to use this function and should have a very good
 *      knowledge of MCA bus before you do so. Doing this wrongly can
 *      damage the hardware.
 *
 *      This function may not be used from interrupt context.
 *
 *      Note that this a technically a Bad Thing, as IBM tech stuff says
 *      you should only set POS values through their utilities.
 *      However, some devices such as the 3c523 recommend that you write
 *      back some data to make sure the configuration is consistent.
 *      I'd say that IBM is right, but I like my drivers to work.
 *
 *      This function can't do checks to see if multiple devices end up
 *      with the same resources, so you might see magic smoke if someone
 *      screws up.
 */

void mca_write_pos(int slot, int reg, unsigned char byte)
{
        struct mca_device *mca_dev = mca_find_device_by_slot(slot);

        if(!mca_dev)
                return;

        mca_device_write_pos(mca_dev, reg, byte);
}
EXPORT_SYMBOL(mca_write_pos);

/**
 *      mca_set_adapter_name - Set the description of the card
 *      @slot: slot to name
 *      @name: text string for the namen
 *
 *      This function sets the name reported via /proc for this
 *      adapter slot. This is for user information only. Setting a
 *      name deletes any previous name.
 */

void mca_set_adapter_name(int slot, char* name)
{
        struct mca_device *mca_dev = mca_find_device_by_slot(slot);

        if(!mca_dev)
                return;

        mca_device_set_name(mca_dev, name);
}
EXPORT_SYMBOL(mca_set_adapter_name);

/**
 *      mca_mark_as_used - claim an MCA device
 *      @slot:  slot to claim
 *      FIXME:  should we make this threadsafe
 *
 *      Claim an MCA slot for a device driver. If the
 *      slot is already taken the function returns 1,
 *      if it is not taken it is claimed and 0 is
 *      returned.
 */

int mca_mark_as_used(int slot)
{
        struct mca_device *mca_dev = mca_find_device_by_slot(slot);

        if(!mca_dev)
                /* FIXME: this is actually a severe error */
                return 1;

        if(mca_device_claimed(mca_dev))
                return 1;

        mca_device_set_claim(mca_dev, 1);

        return 0;
}
EXPORT_SYMBOL(mca_mark_as_used);

/**
 *      mca_mark_as_unused - release an MCA device
 *      @slot:  slot to claim
 *
 *      Release the slot for other drives to use.
 */

void mca_mark_as_unused(int slot)
{
        struct mca_device *mca_dev = mca_find_device_by_slot(slot);

        if(!mca_dev)
                return;

        mca_device_set_claim(mca_dev, 0);
}
EXPORT_SYMBOL(mca_mark_as_unused);