/*
    module/drivers.c
    functions for manipulating drivers

    COMEDI - Linux Control and Measurement Device Interface
    Copyright (C) 1997-2000 David A. Schleef <ds@schleef.org>

    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/device.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/kconfig.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/fcntl.h>
#include <linux/delay.h>
#include <linux/ioport.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/highmem.h>      /* for SuSE brokenness */
#include <linux/vmalloc.h>
#include <linux/cdev.h>
#include <linux/dma-mapping.h>
#include <linux/io.h>
#include <linux/interrupt.h>

#include "comedidev.h"
#include "comedi_internal.h"

struct comedi_driver *comedi_drivers;

int comedi_set_hw_dev(struct comedi_device *dev, struct device *hw_dev)
{
        if (hw_dev == dev->hw_dev)
                return 0;
        if (dev->hw_dev != NULL)
                return -EEXIST;
        dev->hw_dev = get_device(hw_dev);
        return 0;
}
EXPORT_SYMBOL_GPL(comedi_set_hw_dev);

static void comedi_clear_hw_dev(struct comedi_device *dev)
{
        put_device(dev->hw_dev);
        dev->hw_dev = NULL;
}

int comedi_alloc_subdevices(struct comedi_device *dev, int num_subdevices)
{
        struct comedi_subdevice *s;
        int i;

        if (num_subdevices < 1)
                return -EINVAL;

        s = kcalloc(num_subdevices, sizeof(*s), GFP_KERNEL);
        if (!s)
                return -ENOMEM;
        dev->subdevices = s;
        dev->n_subdevices = num_subdevices;

        for (i = 0; i < num_subdevices; ++i) {
                s = &dev->subdevices[i];
                s->device = dev;
                s->index = i;
                s->async_dma_dir = DMA_NONE;
                spin_lock_init(&s->spin_lock);
                s->minor = -1;
        }
        return 0;
}
EXPORT_SYMBOL_GPL(comedi_alloc_subdevices);

void comedi_spriv_free(struct comedi_device *dev, int subdev_num)
{
        struct comedi_subdevice *s;

        if (dev->subdevices && subdev_num < dev->n_subdevices) {
                s = &dev->subdevices[subdev_num];
                kfree(s->private);
                s->private = NULL;
        }
}
EXPORT_SYMBOL_GPL(comedi_spriv_free);

static void cleanup_device(struct comedi_device *dev)
{
        int i;
        struct comedi_subdevice *s;

        if (dev->subdevices) {
                for (i = 0; i < dev->n_subdevices; i++) {
                        s = &dev->subdevices[i];
                        comedi_free_subdevice_minor(s);
                        if (s->async) {
                                comedi_buf_alloc(dev, s, 0);
                                kfree(s->async);
                        }
                }
                kfree(dev->subdevices);
                dev->subdevices = NULL;
                dev->n_subdevices = 0;
        }
        kfree(dev->private);
        dev->private = NULL;
        dev->driver = NULL;
        dev->board_name = NULL;
        dev->board_ptr = NULL;
        dev->iobase = 0;
        dev->iolen = 0;
        dev->ioenabled = false;
        dev->irq = 0;
        dev->read_subdev = NULL;
        dev->write_subdev = NULL;
        dev->open = NULL;
        dev->close = NULL;
        comedi_clear_hw_dev(dev);
}

void comedi_device_detach(struct comedi_device *dev)
{
        dev->attached = false;
        if (dev->driver)
                dev->driver->detach(dev);
        cleanup_device(dev);
}

static int poll_invalid(struct comedi_device *dev, struct comedi_subdevice *s)
{
        return -EINVAL;
}

int insn_inval(struct comedi_device *dev, struct comedi_subdevice *s,
               struct comedi_insn *insn, unsigned int *data)
{
        return -EINVAL;
}

static int insn_rw_emulate_bits(struct comedi_device *dev,
                                struct comedi_subdevice *s,
                                struct comedi_insn *insn, unsigned int *data)
{
        struct comedi_insn new_insn;
        int ret;
        static const unsigned channels_per_bitfield = 32;

        unsigned chan = CR_CHAN(insn->chanspec);
        const unsigned base_bitfield_channel =
            (chan < channels_per_bitfield) ? 0 : chan;
        unsigned int new_data[2];
        memset(new_data, 0, sizeof(new_data));
        memset(&new_insn, 0, sizeof(new_insn));
        new_insn.insn = INSN_BITS;
        new_insn.chanspec = base_bitfield_channel;
        new_insn.n = 2;
        new_insn.subdev = insn->subdev;

        if (insn->insn == INSN_WRITE) {
                if (!(s->subdev_flags & SDF_WRITABLE))
                        return -EINVAL;
                new_data[0] = 1 << (chan - base_bitfield_channel); /* mask */
                new_data[1] = data[0] ? (1 << (chan - base_bitfield_channel))
                              : 0; /* bits */
        }

        ret = s->insn_bits(dev, s, &new_insn, new_data);
        if (ret < 0)
                return ret;

        if (insn->insn == INSN_READ)
                data[0] = (new_data[1] >> (chan - base_bitfield_channel)) & 1;

        return 1;
}

static int __comedi_device_postconfig_async(struct comedi_device *dev,
                                            struct comedi_subdevice *s)
{
        struct comedi_async *async;
        unsigned int buf_size;
        int ret;

        if ((s->subdev_flags & (SDF_CMD_READ | SDF_CMD_WRITE)) == 0) {
                dev_warn(dev->class_dev,
                         "async subdevices must support SDF_CMD_READ or SDF_CMD_WRITE\n");
                return -EINVAL;
        }
        if (!s->do_cmdtest) {
                dev_warn(dev->class_dev,
                         "async subdevices must have a do_cmdtest() function\n");
                return -EINVAL;
        }

        async = kzalloc(sizeof(*async), GFP_KERNEL);
        if (!async)
                return -ENOMEM;

        init_waitqueue_head(&async->wait_head);
        async->subdevice = s;
        s->async = async;

        async->max_bufsize = comedi_default_buf_maxsize_kb * 1024;
        buf_size = comedi_default_buf_size_kb * 1024;
        if (buf_size > async->max_bufsize)
                buf_size = async->max_bufsize;

        if (comedi_buf_alloc(dev, s, buf_size) < 0) {
                dev_warn(dev->class_dev, "Buffer allocation failed\n");
                return -ENOMEM;
        }
        if (s->buf_change) {
                ret = s->buf_change(dev, s, buf_size);
                if (ret < 0)
                        return ret;
        }

        comedi_alloc_subdevice_minor(s);

        return 0;
}

static int __comedi_device_postconfig(struct comedi_device *dev)
{
        struct comedi_subdevice *s;
        int ret;
        int i;

        for (i = 0; i < dev->n_subdevices; i++) {
                s = &dev->subdevices[i];

                if (s->type == COMEDI_SUBD_UNUSED)
                        continue;

                if (s->len_chanlist == 0)
                        s->len_chanlist = 1;

                if (s->do_cmd) {
                        ret = __comedi_device_postconfig_async(dev, s);
                        if (ret)
                                return ret;
                }

                if (!s->range_table && !s->range_table_list)
                        s->range_table = &range_unknown;

                if (!s->insn_read && s->insn_bits)
                        s->insn_read = insn_rw_emulate_bits;
                if (!s->insn_write && s->insn_bits)
                        s->insn_write = insn_rw_emulate_bits;

                if (!s->insn_read)
                        s->insn_read = insn_inval;
                if (!s->insn_write)
                        s->insn_write = insn_inval;
                if (!s->insn_bits)
                        s->insn_bits = insn_inval;
                if (!s->insn_config)
                        s->insn_config = insn_inval;

                if (!s->poll)
                        s->poll = poll_invalid;
        }

        return 0;
}

/* do a little post-config cleanup */
static int comedi_device_postconfig(struct comedi_device *dev)
{
        int ret;

        ret = __comedi_device_postconfig(dev);
        if (ret < 0)
                return ret;
        smp_wmb();
        dev->attached = true;
        return 0;
}

/*
 * Generic recognize function for drivers that register their supported
 * board names.
 *
 * 'driv->board_name' points to a 'const char *' member within the
 * zeroth element of an array of some private board information
 * structure, say 'struct foo_board' containing a member 'const char
 * *board_name' that is initialized to point to a board name string that
 * is one of the candidates matched against this function's 'name'
 * parameter.
 *
 * 'driv->offset' is the size of the private board information
 * structure, say 'sizeof(struct foo_board)', and 'driv->num_names' is
 * the length of the array of private board information structures.
 *
 * If one of the board names in the array of private board information
 * structures matches the name supplied to this function, the function
 * returns a pointer to the pointer to the board name, otherwise it
 * returns NULL.  The return value ends up in the 'board_ptr' member of
 * a 'struct comedi_device' that the low-level comedi driver's
 * 'attach()' hook can convert to a point to a particular element of its
 * array of private board information structures by subtracting the
 * offset of the member that points to the board name.  (No subtraction
 * is required if the board name pointer is the first member of the
 * private board information structure, which is generally the case.)
 */
static void *comedi_recognize(struct comedi_driver *driv, const char *name)
{
        char **name_ptr = (char **)driv->board_name;
        int i;

        for (i = 0; i < driv->num_names; i++) {
                if (strcmp(*name_ptr, name) == 0)
                        return name_ptr;
                name_ptr = (void *)name_ptr + driv->offset;
        }

        return NULL;
}

static void comedi_report_boards(struct comedi_driver *driv)
{
        unsigned int i;
        const char *const *name_ptr;

        pr_info("comedi: valid board names for %s driver are:\n",
                driv->driver_name);

        name_ptr = driv->board_name;
        for (i = 0; i < driv->num_names; i++) {
                pr_info(" %s\n", *name_ptr);
                name_ptr = (const char **)((char *)name_ptr + driv->offset);
        }

        if (driv->num_names == 0)
                pr_info(" %s\n", driv->driver_name);
}

/**
 * __comedi_request_region() - Request an I/O reqion for a legacy driver.
 * @dev: comedi_device struct
 * @start: base address of the I/O reqion
 * @len: length of the I/O region
 */
int __comedi_request_region(struct comedi_device *dev,
                            unsigned long start, unsigned long len)
{
        if (!start) {
                dev_warn(dev->class_dev,
                         "%s: a I/O base address must be specified\n",
                         dev->board_name);
                return -EINVAL;
        }

        if (!request_region(start, len, dev->board_name)) {
                dev_warn(dev->class_dev, "%s: I/O port conflict (%#lx,%lu)\n",
                         dev->board_name, start, len);
                return -EIO;
        }

        return 0;
}
EXPORT_SYMBOL_GPL(__comedi_request_region);

/**
 * comedi_request_region() - Request an I/O reqion for a legacy driver.
 * @dev: comedi_device struct
 * @start: base address of the I/O reqion
 * @len: length of the I/O region
 */
int comedi_request_region(struct comedi_device *dev,
                          unsigned long start, unsigned long len)
{
        int ret;

        ret = __comedi_request_region(dev, start, len);
        if (ret == 0) {
                dev->iobase = start;
                dev->iolen = len;
        }

        return ret;
}
EXPORT_SYMBOL_GPL(comedi_request_region);

/**
 * comedi_legacy_detach() - A generic (*detach) function for legacy drivers.
 * @dev: comedi_device struct
 */
void comedi_legacy_detach(struct comedi_device *dev)
{
        if (dev->irq) {
                free_irq(dev->irq, dev);
                dev->irq = 0;
        }
        if (dev->iobase && dev->iolen) {
                release_region(dev->iobase, dev->iolen);
                dev->iobase = 0;
                dev->iolen = 0;
        }
}
EXPORT_SYMBOL_GPL(comedi_legacy_detach);

int comedi_device_attach(struct comedi_device *dev, struct comedi_devconfig *it)
{
        struct comedi_driver *driv;
        int ret;

        if (dev->attached)
                return -EBUSY;

        for (driv = comedi_drivers; driv; driv = driv->next) {
                if (!try_module_get(driv->module))
                        continue;
                if (driv->num_names) {
                        dev->board_ptr = comedi_recognize(driv, it->board_name);
                        if (dev->board_ptr)
                                break;
                } else if (strcmp(driv->driver_name, it->board_name) == 0)
                        break;
                module_put(driv->module);
        }
        if (driv == NULL) {
                /*  recognize has failed if we get here */
                /*  report valid board names before returning error */
                for (driv = comedi_drivers; driv; driv = driv->next) {
                        if (!try_module_get(driv->module))
                                continue;
                        comedi_report_boards(driv);
                        module_put(driv->module);
                }
                return -EIO;
        }
        if (driv->attach == NULL) {
                /* driver does not support manual configuration */
                dev_warn(dev->class_dev,
                         "driver '%s' does not support attach using comedi_config\n",
                         driv->driver_name);
                module_put(driv->module);
                return -ENOSYS;
        }
        /* initialize dev->driver here so
         * comedi_error() can be called from attach */
        dev->driver = driv;
        dev->board_name = dev->board_ptr ? *(const char **)dev->board_ptr
                                         : dev->driver->driver_name;
        ret = driv->attach(dev, it);
        if (ret >= 0)
                ret = comedi_device_postconfig(dev);
        if (ret < 0) {
                comedi_device_detach(dev);
                module_put(dev->driver->module);
        }
        /* On success, the driver module count has been incremented. */
        return ret;
}

int comedi_auto_config(struct device *hardware_device,
                       struct comedi_driver *driver, unsigned long context)
{
        struct comedi_device *dev;
        int ret;

        if (!hardware_device) {
                pr_warn("BUG! comedi_auto_config called with NULL hardware_device\n");
                return -EINVAL;
        }
        if (!driver) {
                dev_warn(hardware_device,
                         "BUG! comedi_auto_config called with NULL comedi driver\n");
                return -EINVAL;
        }

        if (!driver->auto_attach) {
                dev_warn(hardware_device,
                         "BUG! comedi driver '%s' has no auto_attach handler\n",
                         driver->driver_name);
                return -EINVAL;
        }

        dev = comedi_alloc_board_minor(hardware_device);
        if (IS_ERR(dev))
                return PTR_ERR(dev);
        /* Note: comedi_alloc_board_minor() locked dev->mutex. */

        dev->driver = driver;
        dev->board_name = dev->driver->driver_name;
        ret = driver->auto_attach(dev, context);
        if (ret >= 0)
                ret = comedi_device_postconfig(dev);
        if (ret < 0)
                comedi_device_detach(dev);
        mutex_unlock(&dev->mutex);

        if (ret < 0)
                comedi_release_hardware_device(hardware_device);
        return ret;
}
EXPORT_SYMBOL_GPL(comedi_auto_config);

void comedi_auto_unconfig(struct device *hardware_device)
{
        if (hardware_device == NULL)
                return;
        comedi_release_hardware_device(hardware_device);
}
EXPORT_SYMBOL_GPL(comedi_auto_unconfig);

int comedi_driver_register(struct comedi_driver *driver)
{
        driver->next = comedi_drivers;
        comedi_drivers = driver;

        return 0;
}
EXPORT_SYMBOL_GPL(comedi_driver_register);

int comedi_driver_unregister(struct comedi_driver *driver)
{
        struct comedi_driver *prev;
        int i;

        /* check for devices using this driver */
        for (i = 0; i < COMEDI_NUM_BOARD_MINORS; i++) {
                struct comedi_device *dev = comedi_dev_from_minor(i);

                if (!dev)
                        continue;

                mutex_lock(&dev->mutex);
                if (dev->attached && dev->driver == driver) {
                        if (dev->use_count)
                                dev_warn(dev->class_dev,
                                         "BUG! detaching device with use_count=%d\n",
                                         dev->use_count);
                        comedi_device_detach(dev);
                }
                mutex_unlock(&dev->mutex);
        }

        if (comedi_drivers == driver) {
                comedi_drivers = driver->next;
                return 0;
        }

        for (prev = comedi_drivers; prev->next; prev = prev->next) {
                if (prev->next == driver) {
                        prev->next = driver->next;
                        return 0;
                }
        }
        return -EINVAL;
}
EXPORT_SYMBOL_GPL(comedi_driver_unregister);