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/*
* pio.c -- low level functions I/O ports
*
* 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.
*
* Written by Soós Péter <sp@osb.hu>, 2002-2004
* Modified by Mathieu Bérard <mathieu.berard@crans.org>, 2006
*/
#include "omnibook.h"
#include <linux/types.h>
#include <linux/delay.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/ioport.h>
#include <asm/io.h>
#include "hardware.h"
/*
* IO port backend. Only support single or dual ports operations
* private data structure: it's the linked list of requested ports
*
* Race condition issue: omnibook_pio_init/exit functions are only called from
* omnibook_backend_match and omnibook_remove from init.c, this should happen
* only at module init/exit time so there is no need for a lock.
*/
struct pio_priv_data_t {
unsigned long addr;
struct kref refcount;
struct list_head list;
};
static struct pio_priv_data_t pio_priv_data = {
.addr = 0,
.list = LIST_HEAD_INIT(pio_priv_data.list),
};
/*
* Match an entry in the linked list helper function: see if we have and entry
* whose addr field match maddr
*/
static struct pio_priv_data_t *omnibook_match_port(struct pio_priv_data_t *data,
unsigned long maddr)
{
struct pio_priv_data_t *cursor;
list_for_each_entry(cursor, &data->list, list) {
if (cursor->addr == maddr) {
return cursor;
}
}
return NULL;
}
/*
* See if we have to request raddr
*/
static int omnibook_claim_port(struct pio_priv_data_t *data, unsigned long raddr)
{
struct pio_priv_data_t *match, *new;
match = omnibook_match_port(data, raddr);
if (match) {
/* Already requested by us: increment kref and quit */
kref_get(&match->refcount);
return 0;
}
/* there was no match: request the region and add to list */
if (!request_region(raddr, 1, OMNIBOOK_MODULE_NAME)) {
printk(O_ERR "Request I/O port error\n");
return -ENODEV;
}
new = kmalloc(sizeof(struct pio_priv_data_t), GFP_KERNEL);
if (!new) {
release_region(raddr, 1);
return -ENOMEM;
}
kref_init(&new->refcount);
new->addr = raddr;
list_add(&new->list, &data->list);
return 0;
}
/*
* Register read_addr and write_addr
*/
static int omnibook_pio_init(const struct omnibook_operation *io_op)
{
int retval = 0;
if (io_op->read_addr
&& (retval = omnibook_claim_port(io_op->backend->data, io_op->read_addr)))
goto out;
if (io_op->write_addr && (io_op->write_addr != io_op->read_addr))
retval = omnibook_claim_port(io_op->backend->data, io_op->write_addr);
out:
return retval;
}
/*
* REALLY release a port
*/
static void omnibook_free_port(struct kref *ref)
{
struct pio_priv_data_t *data;
data = container_of(ref, struct pio_priv_data_t, refcount);
release_region(data->addr, 1);
list_del(&data->list);
kfree(data);
}
/*
* Unregister read_addr and write_addr
*/
static void omnibook_pio_exit(const struct omnibook_operation *io_op)
{
struct pio_priv_data_t *match;
match = omnibook_match_port(io_op->backend->data, io_op->read_addr);
if (match)
kref_put(&match->refcount, omnibook_free_port);
match = omnibook_match_port(io_op->backend->data, io_op->write_addr);
if (match)
kref_put(&match->refcount, omnibook_free_port);
}
static int omnibook_io_read(const struct omnibook_operation *io_op, u8 * value)
{
*value = inb(io_op->read_addr);
if (io_op->read_mask)
*value &= io_op->read_mask;
return 0;
}
static int omnibook_io_write(const struct omnibook_operation *io_op, u8 value)
{
outb(io_op->write_addr, value);
return 0;
}
/*
* Backend interface declarations
*/
struct omnibook_backend pio_backend = {
.name = "pio",
.data = &pio_priv_data,
.init = omnibook_pio_init,
.exit = omnibook_pio_exit,
.byte_read = omnibook_io_read,
.byte_write = omnibook_io_write,
};
/* End of file */
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