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/*
* Copyright (c) 2023-2024 Ian Marco Moffett and the Osmora Team.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of Hyra nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/device.h>
#include <sys/types.h>
#include <sys/errno.h>
#include <vm/dynalloc.h>
#include <string.h>
#define MAX_MAJOR 256
#define MAX_MINOR 256
struct device_major {
void **devsw_tab;
uint16_t devsw_count;
};
static struct device_major devtab[MAX_MAJOR];
/*
* Allocate a device major.
*
* Returns 0 on failure.
*/
devmajor_t
dev_alloc_major(void)
{
static devmajor_t next = 1;
if (next > MAX_MAJOR)
return 0;
return next++;
}
/*
* Allocates a device minor.
*
* @major: Major number for class of device.
*
* Returns 0 on failure.
*/
dev_t
dev_alloc(devmajor_t major)
{
struct device_major *devmajor;
size_t allocsize;
if (major >= MAX_MAJOR)
return 0;
devmajor = &devtab[major];
if (devmajor->devsw_count >= MAX_MINOR)
return 0;
/*
* Try to allocate a devsw table if needed.
*
* XXX: If MAX_MINOR is 256 then we'll need roughly 8 * 256
* (2048) bytes to store each table. Perhaps we should
* figure out a way we can save memory?
*/
if (devmajor->devsw_tab == NULL) {
allocsize = sizeof(void *) * MAX_MINOR;
devmajor->devsw_tab = dynalloc(allocsize);
if (devmajor->devsw_tab == NULL)
return 0;
memset(devmajor->devsw_tab, 0, allocsize);
}
return ++devmajor->devsw_count;
}
/*
* Register a device.
*
* Returns less than zero value on failure.
*/
int
dev_register(devmajor_t major, dev_t dev, void *devsw)
{
struct device_major *devmajor;
if (major >= MAX_MAJOR)
return -EINVAL;
devmajor = &devtab[major];
if (dev > devmajor->devsw_count)
return -EINVAL;
devmajor->devsw_tab[dev] = devsw;
return 0;
}
/*
* Get a devsw structure from device major
* and minor numbers.
*
* @major: Major number to lookup.
* @dev: Minor number to lookup.
*/
void *
dev_get(devmajor_t major, dev_t dev)
{
struct device_major *devmajor;
if (major >= MAX_MAJOR)
return 0;
devmajor = &devtab[major];
if (dev > devmajor->devsw_count)
return NULL;
return devmajor->devsw_tab[dev];
}
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