path: root/drivers/input/serio/hil_mlc.c

/*
 * HIL MLC state machine and serio interface driver
 *
 * Copyright (c) 2001 Brian S. Julin
 * 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,
 *    without modification.
 * 2. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL").
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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
 *
 * References:
 * HP-HIL Technical Reference Manual.  Hewlett Packard Product No. 45918A
 *
 *
 *	Driver theory of operation:
 *
 *	Some access methods and an ISR is defined by the sub-driver
 *	(e.g. hp_sdc_mlc.c).  These methods are expected to provide a
 *	few bits of logic in addition to raw access to the HIL MLC,
 *	specifically, the ISR, which is entirely registered by the
 *	sub-driver and invoked directly, must check for record
 *	termination or packet match, at which point a semaphore must
 *	be cleared and then the hil_mlcs_tasklet must be scheduled.
 *
 *	The hil_mlcs_tasklet processes the state machine for all MLCs
 *	each time it runs, checking each MLC's progress at the current
 *	node in the state machine, and moving the MLC to subsequent nodes
 *	in the state machine when appropriate.  It will reschedule
 *	itself if output is pending.  (This rescheduling should be replaced
 *	at some point with a sub-driver-specific mechanism.)
 *
 *	A timer task prods the tasklet once per second to prevent
 *	hangups when attached devices do not return expected data
 *	and to initiate probes of the loop for new devices.
 */

#include <linux/hil_mlc.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/timer.h>
#include <linux/list.h>

MODULE_AUTHOR("Brian S. Julin <bri@calyx.com>");
MODULE_DESCRIPTION("HIL MLC serio");
MODULE_LICENSE("Dual BSD/GPL");

EXPORT_SYMBOL(hil_mlc_register);
EXPORT_SYMBOL(hil_mlc_unregister);

#define PREFIX "HIL MLC: "

static LIST_HEAD(hil_mlcs);
static DEFINE_RWLOCK(hil_mlcs_lock);
static struct timer_list	hil_mlcs_kicker;
static int			hil_mlcs_probe;

static void hil_mlcs_process(unsigned long unused);
DECLARE_TASKLET_DISABLED(hil_mlcs_tasklet, hil_mlcs_process, 0);


/* #define HIL_MLC_DEBUG */

/********************** Device info/instance management **********************/

static void hil_mlc_clear_di_map(hil_mlc *mlc, int val)
{
	int j;

	for (j = val; j < 7 ; j++)
		mlc->di_map[j] = -1;
}

static void hil_mlc_clear_di_scratch(hil_mlc *mlc)
{
	memset(&mlc->di_scratch, 0, sizeof(mlc->di_scratch));
}

static void hil_mlc_copy_di_scratch(hil_mlc *mlc, int idx)
{
	memcpy(&mlc->di[idx], &mlc->di_scratch, sizeof(mlc->di_scratch));
}

static int hil_mlc_match_di_scratch(hil_mlc *mlc)
{
	int idx;

	for (idx = 0; idx < HIL_MLC_DEVMEM; idx++) {
		int j, found = 0;

		/* In-use slots are not eligible. */
		for (j = 0; j < 7 ; j++)
			if (mlc->di_map[j] == idx)
				found++;

		if (found)
			continue;

		if (!memcmp(mlc->di + idx, &mlc->di_scratch,
				sizeof(mlc->di_scratch)))
			break;
	}
	return idx >= HIL_MLC_DEVMEM ? -1 : idx;
}

static int hil_mlc_find_free_di(hil_mlc *mlc)
{
	int idx;

	/* TODO: Pick all-zero slots first, failing that,
	 * randomize the slot picked among those eligible.
	 */
	for (idx = 0; idx < HIL_MLC_DEVMEM; idx++) {
		int j, found = 0;

		for (j = 0; j < 7 ; j++)
			if (mlc->di_map[j] == idx)
				found++;

		if (!found)
			break;
	}

	return idx; /* Note: It is guaranteed at least one above will match */
}

static inline void hil_mlc_clean_serio_map(hil_mlc *mlc)
{
	int idx;

	for (idx = 0; idx < HIL_MLC_DEVMEM; idx++) {
		int j, found = 0;

		for (j = 0; j < 7 ; j++)
			if (mlc->di_map[j] == idx)
				found++;

		if (!found)
			mlc->serio_map[idx].di_revmap = -1;
	}
}

static void hil_mlc_send_polls(hil_mlc *mlc)
{
	int did, i, cnt;
	struct serio *serio;
	struct serio_driver *drv;

	i = cnt = 0;
	did = (mlc->ipacket[0] & HIL_PKT_ADDR_MASK) >> 8;
	serio = did ? mlc->