cregit-Linux how code gets into the kernel

Release 4.11 drivers/input/serio/hp_sdc.c

Directory: drivers/input/serio
/*
 * HP i8042-based System Device Controller 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:
 * System Device Controller Microprocessor Firmware Theory of Operation
 *      for Part Number 1820-4784 Revision B.  Dwg No. A-1820-4784-2
 * Helge Deller's original hilkbd.c port for PA-RISC.
 *
 *
 * Driver theory of operation:
 *
 * hp_sdc_put does all writing to the SDC.  ISR can run on a different
 * CPU than hp_sdc_put, but only one CPU runs hp_sdc_put at a time
 * (it cannot really benefit from SMP anyway.)  A tasket fit this perfectly.
 *
 * All data coming back from the SDC is sent via interrupt and can be read
 * fully in the ISR, so there are no latency/throughput problems there.
 * The problem is with output, due to the slow clock speed of the SDC
 * compared to the CPU.  This should not be too horrible most of the time,
 * but if used with HIL devices that support the multibyte transfer command,
 * keeping outbound throughput flowing at the 6500KBps that the HIL is
 * capable of is more than can be done at HZ=100.
 *
 * Busy polling for IBF clear wastes CPU cycles and bus cycles.  hp_sdc.ibf
 * is set to 0 when the IBF flag in the status register has cleared.  ISR
 * may do this, and may also access the parts of queued transactions related
 * to reading data back from the SDC, but otherwise will not touch the
 * hp_sdc state. Whenever a register is written hp_sdc.ibf is set to 1.
 *
 * The i8042 write index and the values in the 4-byte input buffer
 * starting at 0x70 are kept track of in hp_sdc.wi, and .r7[], respectively,
 * to minimize the amount of IO needed to the SDC.  However these values
 * do not need to be locked since they are only ever accessed by hp_sdc_put.
 *
 * A timer task schedules the tasklet once per second just to make
 * sure it doesn't freeze up and to allow for bad reads to time out.
 */

#include <linux/hp_sdc.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/ioport.h>
#include <linux/time.h>
#include <linux/semaphore.h>
#include <linux/slab.h>
#include <linux/hil.h>
#include <asm/io.h>

/* Machine-specific abstraction */

#if defined(__hppa__)
# include <asm/parisc-device.h>

# define sdc_readb(p)		gsc_readb(p)

# define sdc_writeb(v,p)	gsc_writeb((v),(p))
#elif defined(__mc68000__)
#include <linux/uaccess.h>

# define sdc_readb(p)		in_8(p)

# define sdc_writeb(v,p)	out_8((p),(v))
#else
# error "HIL is not supported on this platform"
#endif


#define PREFIX "HP SDC: "

MODULE_AUTHOR("Brian S. Julin <bri@calyx.com>");
MODULE_DESCRIPTION("HP i8042-based SDC Driver");
MODULE_LICENSE("Dual BSD/GPL");


EXPORT_SYMBOL(hp_sdc_request_timer_irq);

EXPORT_SYMBOL(hp_sdc_request_hil_irq);

EXPORT_SYMBOL(hp_sdc_request_cooked_irq);


EXPORT_SYMBOL(hp_sdc_release_timer_irq);

EXPORT_SYMBOL(hp_sdc_release_hil_irq);

EXPORT_SYMBOL(hp_sdc_release_cooked_irq);


EXPORT_SYMBOL(__hp_sdc_enqueue_transaction);

EXPORT_SYMBOL(hp_sdc_enqueue_transaction);

EXPORT_SYMBOL(hp_sdc_dequeue_transaction);


static bool hp_sdc_disabled;
module_param_named(no_hpsdc, hp_sdc_disabled, bool, 0);
MODULE_PARM_DESC(no_hpsdc, "Do not enable HP SDC driver.");


static hp_i8042_sdc	hp_sdc;	
/* All driver state is kept in here. */

/*************** primitives for use in any context *********************/



static inline uint8_t hp_sdc_status_in8(void)
{
	uint8_t status;
	unsigned long flags;

	write_lock_irqsave(&hp_sdc.ibf_lock, flags);
	status = sdc_readb(hp_sdc.status_io);
	if (!(status & HP_SDC_STATUS_IBF))
		hp_sdc.ibf = 0;
	write_unlock_irqrestore(&hp_sdc.ibf_lock, flags);

	return status;
}


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static inline uint8_t hp_sdc_data_in8(void)
{
	return sdc_readb(hp_sdc.data_io);
}


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static inline void hp_sdc_status_out8(uint8_t val)
{
	unsigned long flags;

	write_lock_irqsave(&hp_sdc.ibf_lock, flags);
	hp_sdc.ibf = 1;
	if ((val & 0xf0) == 0xe0)
		hp_sdc.wi = 0xff;
	sdc_writeb(val, hp_sdc.status_io);
	write_unlock_irqrestore(&hp_sdc.ibf_lock, flags);
}


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static inline void hp_sdc_data_out8(uint8_t val)
{
	unsigned long flags;

	write_lock_irqsave(&hp_sdc.ibf_lock, flags);
	hp_sdc.ibf = 1;
	sdc_writeb(val, hp_sdc.data_io);
	write_unlock_irqrestore(&hp_sdc.ibf_lock, flags);
}


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/*      Care must be taken to only invoke hp_sdc_spin_ibf when
 *      absolutely needed, or in rarely invoked subroutines.
 *      Not only does it waste CPU cycles, it also wastes bus cycles.
 */



static inline void hp_sdc_spin_ibf(void)
{
	unsigned long flags;
	rwlock_t *lock;

	lock = &hp_sdc.ibf_lock;

	read_lock_irqsave(lock, flags);
	if (!hp_sdc.ibf) {
		read_unlock_irqrestore(lock, flags);
		return;
	}
	read_unlock(lock);
	write_lock(lock);
	while (sdc_readb(hp_sdc.status_io) & HP_SDC_STATUS_IBF)
		{ }
	hp_sdc.ibf = 0;
	write_unlock_irqrestore(lock, flags);
}



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/************************ Interrupt context functions ************************/



static void hp_sdc_take(int irq, void *dev_id, uint8_t status, uint8_t data)
{
	hp_sdc_transaction *curr;

	read_lock(&hp_sdc.rtq_lock);
	if (hp_sdc.rcurr < 0) {
		read_unlock(&hp_sdc.rtq_lock);
		return;
	}
	curr = hp_sdc.tq[hp_sdc.rcurr];
	read_unlock(&hp_sdc.rtq_lock);

	curr->seq[curr->idx++] = status;
	curr->seq[curr->idx++] = data;
	hp_sdc.rqty -= 2;
	do_gettimeofday(&hp_sdc.rtv);

	if (hp_sdc.rqty <= 0) {
		/* All data has been gathered. */
		if (curr->seq[curr->actidx] & HP_SDC_ACT_SEMAPHORE)
			if (curr->act.semaphore)
				up(curr->act.semaphore);

		if (curr->seq[curr->actidx] & HP_SDC_ACT_CALLBACK)
			if (curr->act.irqhook)
				curr->act.irqhook(irq, dev_id, status, data);

		curr->actidx = curr->idx;
		curr->idx++;
		/* Return control of this transaction */
		write_lock(&hp_sdc.rtq_lock);
		hp_sdc.rcurr = -1;
		hp_sdc.rqty = 0;
		write_unlock(&hp_sdc.rtq_lock);
		tasklet_schedule(&hp_sdc.task);
	}
}


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static irqreturn_t hp_sdc_isr(int irq, void *dev_id)
{
	uint8_t status, data;

	status = hp_sdc_status_in8();
	/* Read data unconditionally to advance i8042. */
	data =   hp_sdc_data_in8();

	/* For now we are ignoring these until we get the SDC to behave. */
	if (((status & 0xf1) == 0x51) && data == 0x82)
		return IRQ_HANDLED;

	switch (status & HP_SDC_STATUS_IRQMASK) {
	case 0: /* This case is not documented. */
		break;

	case HP_SDC_STATUS_USERTIMER:
	case HP_SDC_STATUS_PERIODIC:
	case HP_SDC_STATUS_TIMER:
		read_lock(&hp_sdc.hook_lock);
		if (hp_sdc.timer != NULL)
			hp_sdc.timer(irq, dev_id, status, data);
		read_unlock(&hp_sdc.hook_lock);
		break;

	case HP_SDC_STATUS_REG:
		hp_sdc_take(irq, dev_id, status, data);
		break;

	case HP_SDC_STATUS_HILCMD:
	case HP_SDC_STATUS_HILDATA:
		read_lock(&hp_sdc.hook_lock);
		if (hp_sdc.hil != NULL)
			hp_sdc.hil(irq, dev_id, status, data);
		read_unlock(&hp_sdc.hook_lock);
		break;

	case HP_SDC_STATUS_PUP:
		read_lock(&hp_sdc.hook_lock);
		if (hp_sdc.pup != NULL)
			hp_sdc.pup(irq, dev_id, status, data);
		else
			printk(KERN_INFO PREFIX "HP SDC reports successful PUP.\n");
		read_unlock(&hp_sdc.hook_lock);
		break;

	default:
		read_lock(&hp_sdc.hook_lock);
		if (hp_sdc.cooked != NULL)
			hp_sdc.cooked(irq, dev_id, status, data);
		read_unlock(&hp_sdc.hook_lock);
		break;
	}

	return IRQ_HANDLED;
}



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static irqreturn_t hp_sdc_nmisr(int irq, void *dev_id)
{
	int status;

	status = hp_sdc_status_in8();
	printk(KERN_WARNING PREFIX "NMI !\n");

#if 0
	if (status & HP_SDC_NMISTATUS_FHS) {
                read_lock(&hp_sdc.hook_lock);
                if (hp_sdc.timer != NULL)
                        hp_sdc.timer(irq, dev_id, status, 0);
                read_unlock(&hp_sdc.hook_lock);
        } else {
		/* TODO: pass this on to the HIL handler, or do SAK here? */
		printk(KERN_WARNING PREFIX "HIL NMI\n");
        }
#endif

	return IRQ_HANDLED;
}



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/***************** Kernel (tasklet) context functions ****************/

unsigned long hp_sdc_put(void);




static void hp_sdc_tasklet(unsigned long foo)
{
	write_lock_irq(&hp_sdc.rtq_lock);

	if (hp_sdc.rcurr >= 0) {
		struct timeval tv;

		do_gettimeofday(&tv);
		if (tv.tv_sec > hp_sdc.rtv.tv_sec)
			tv.tv_usec += USEC_PER_SEC;

		if (tv.tv_usec - hp_sdc.rtv.tv_usec > HP_SDC_MAX_REG_DELAY) {
			hp_sdc_transaction *curr;
			uint8_t tmp;

			curr = hp_sdc.tq[hp_sdc.rcurr];
			/* If this turns out to be a normal failure mode
                         * we'll need to figure out a way to communicate
                         * it back to the application. and be less verbose.
                         */
			printk(KERN_WARNING PREFIX "read timeout (%ius)!\n",
			       (int)(tv.tv_usec - hp_sdc.rtv.tv_usec));
			curr->idx += hp_sdc.rqty;
			hp_sdc.rqty = 0;
			tmp = curr->seq[curr->actidx];
			curr->seq[curr->actidx] |= HP_SDC_ACT_DEAD;
			if (tmp & HP_SDC_ACT_SEMAPHORE)
				if (curr->act.semaphore)
					up(curr->act.semaphore);

			if (tmp & HP_SDC_ACT_CALLBACK) {
				/* Note this means that irqhooks may be called
                                 * in tasklet/bh context.
                                 */
				if (curr->act.irqhook)
					curr->act.irqhook(0, NULL, 0, 0);
			}

			curr->actidx = curr->idx;
			curr->idx++;
			hp_sdc.rcurr = -1;
		}
	}
	write_unlock_irq(&hp_sdc.rtq_lock);
	hp_sdc_put();
}


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unsigned long hp_sdc_put(void)
{
	hp_sdc_transaction *curr;
	uint8_t act;
	int idx, curridx;

	int limit = 0;

	write_lock(&hp_sdc.lock);

	/* If i8042 buffers are full, we cannot do anything that
           requires output, so we skip to the administrativa. */
	if (hp_sdc.ibf) {
		hp_sdc_status_in8();
		if (hp_sdc.ibf)
			goto finish;
	}

 anew:
	/* See if we are in the middle of a sequence. */
	if (hp_sdc.wcurr < 0)
		hp_sdc.wcurr = 0;
	read_lock_irq(&hp_sdc.rtq_lock);
	if (hp_sdc.rcurr == hp_sdc.wcurr)
		hp_sdc.wcurr++;
	read_unlock_irq(&hp_sdc.rtq_lock);
	if (hp_sdc.wcurr >= HP_SDC_QUEUE_LEN)
		hp_sdc.wcurr = 0;
	curridx = hp_sdc.wcurr;

	if (hp_sdc.tq[curridx] != NULL)
		goto start;

	while (++curridx != hp_sdc.wcurr) {
		if (curridx >= HP_SDC_QUEUE_LEN) {
			curridx = -1; /* Wrap to top */
			continue;
		}
		read_lock_irq(&hp_sdc.rtq_lock);
		if (hp_sdc.rcurr == curridx) {
			read_unlock_irq(&hp_sdc.rtq_lock);
			continue;
		}
		read_unlock_irq(&hp_sdc.rtq_lock);
		if (hp_sdc.tq[curridx] != NULL)
			break; /* Found one. */
	}
	if (curridx == hp_sdc.wcurr) { /* There's nothing queued to do. */
		curridx = -1;
	}
	hp_sdc.wcurr = curridx;

 start:

	/* Check to see if the interrupt mask needs to be set. */
	if (hp_sdc.set_im) {
		hp_sdc_status_out8(hp_sdc.im | HP_SDC_CMD_SET_IM);
		hp_sdc.set_im = 0;
		goto finish;
	}

	if (hp_sdc.wcurr == -1)
		goto done;

	curr = hp_sdc.tq[curridx];
	idx = curr->actidx;

	if (curr->actidx >= curr->endidx) {
		hp_sdc.tq[curridx] = NULL;
		/* Interleave outbound data between the transactions. */
		hp_sdc.wcurr++;
		if (hp_sdc.wcurr >= HP_SDC_QUEUE_LEN)
			hp_sdc.wcurr = 0;
		goto finish;
	}

	act = curr->seq[idx];
	idx++;

	if (curr->idx >= curr->endidx) {
		if (act & HP_SDC_ACT_DEALLOC)
			kfree(curr);
		hp_sdc.tq[curridx] = NULL;
		/* Interleave outbound data between the transactions. */
		hp_sdc.wcurr++;
		if (hp_sdc.wcurr >= HP_SDC_QUEUE_LEN)
			hp_sdc.wcurr = 0;
		goto finish;
	}

	while (act & HP_SDC_ACT_PRECMD) {
		if (curr->idx != idx) {
			idx++;
			act &= ~HP_SDC_ACT_PRECMD;
			break;
		}
		hp_sdc_status_out8(curr->seq[idx]);
		curr->idx++;
		/* act finished? */
		if ((act & HP_SDC_ACT_DURING) == HP_SDC_ACT_PRECMD)
			goto actdone;
		/* skip quantity field if data-out sequence follows. */
		if (act & HP_SDC_ACT_DATAOUT)
			curr->idx++;
		goto finish;
	}
	if (act & HP_SDC_ACT_DATAOUT) {
		int qty;

		qty = curr->seq[idx];
		idx++;
		if (curr->idx - idx < qty) {
			hp_sdc_data_out8(curr->seq[curr->idx]);
			curr->idx++;
			/* act finished? */
			if (curr->idx - idx >= qty &&
			    (act & HP_SDC_ACT_DURING) == HP_SDC_ACT_DATAOUT)
				goto actdone;
			goto finish;
		}
		idx += qty;
		act &= ~HP_SDC_ACT_DATAOUT;
	} else
	    while (act & HP_SDC_ACT_DATAREG) {
		int mask;
		uint8_t w7[4];

		mask = curr->seq[idx];
		if (idx != curr->idx) {
			idx++;
			idx += !!(mask & 1);
			idx += !!(mask & 2);
			idx += !!(mask & 4);
			idx += !!(mask & 8);
			act &= ~HP_SDC_ACT_DATAREG;
			break;
		}

		w7[0] = (mask & 1) ? curr->seq[++idx] : hp_sdc.r7[0];
		w7[1] = (mask & 2) ? curr->seq[++idx] : hp_sdc.r7[1];
		w7[2] = (mask & 4) ? curr->seq[++idx] : hp_sdc.r7[2];
		w7[3] = (mask & 8) ? curr->seq[++idx] : hp_sdc.r7[3];

		if (hp_sdc.wi > 0x73 || hp_sdc.wi < 0x70 ||
		    w7[hp_sdc.wi - 0x70] == hp_sdc.r7[hp_sdc.wi - 0x70]) {
			int i = 0;

			/* Need to point the write index register */
			while (i < 4 && w7[i] == hp_sdc.r7[i])
				i++;

			if (i < 4) {
				hp_sdc_status_out8(HP_SDC_CMD_SET_D0 + i);
				hp_sdc.wi = 0x70 + i;
				goto finish;
			}

			idx++;
			if ((act & HP_SDC_ACT_DURING) == HP_SDC_ACT_DATAREG)
				goto actdone;

			curr->idx = idx;
			act &= ~HP_SDC_ACT_DATAREG;
			break;
		}

		hp_sdc_data_out8(w7[hp_sdc.wi - 0x70]);
		hp_sdc.r7[hp_sdc.wi - 0x70] = w7[hp_sdc.wi - 0x70];
		hp_sdc.wi++; /* write index register autoincrements */
		{
			int i = 0;

			while ((i < 4) && w7[i] == hp_sdc.r7[i])
				i++;
			if (i >= 4) {
				curr->idx = idx + 1;
				if ((act & HP_SDC_ACT_DURING) ==
				    HP_SDC_ACT_DATAREG)
					goto actdone;
			}
		}
		goto finish;
	}
	/* We don't go any further in the command if there is a pending read,
           because we don't want interleaved results. */
	read_lock_irq(&hp_sdc.rtq_lock);
	if (hp_sdc.rcurr >= 0) {
		read_unlock_irq(&hp_sdc.rtq_lock);
		goto finish;
	}
	read_unlock_irq(&hp_sdc.rtq_lock);


	if (act & HP_SDC_ACT_POSTCMD) {
		uint8_t postcmd;

		/* curr->idx should == idx at this point. */
		postcmd = curr->seq[idx];
		curr->idx++;
		if (act & HP_SDC_ACT_DATAIN) {

			/* Start a new read */
			hp_sdc.rqty = curr->seq[curr->idx];
			do_gettimeofday(&hp_sdc.rtv);
			curr->idx++;
			/* Still need to lock here in case of spurious irq. */
			write_lock_irq(&hp_sdc.rtq_lock);
			hp_sdc.rcurr = curridx;
			write_unlock_irq(&hp_sdc.rtq_lock);
			hp_sdc_status_out8(postcmd);
			goto finish;
		}
		hp_sdc_status_out8(postcmd);
		goto actdone;
	}

 actdone:
	if (act & HP_SDC_ACT_SEMAPHORE)
		up(curr->act.semaphore);
	else if (act & HP_SDC_ACT_CALLBACK)
		curr->act.irqhook(0,NULL,0,0);

	if (curr->idx >= curr->endidx) { /* This transaction is over. */
		if (act & HP_SDC_ACT_DEALLOC)
			kfree(curr);
		hp_sdc.tq[curridx] = NULL;
	} else {
		curr->actidx = idx + 1;
		curr->idx = idx + 2;
	}
	/* Interleave outbound data between the transactions. */
	hp_sdc.wcurr++;
	if (hp_sdc.wcurr >= HP_SDC_QUEUE_LEN)
		hp_sdc.wcurr = 0;

 finish:
	/* If by some quirk IBF has cleared and our ISR has run to
           see that that has happened, do it all again. */
	if (!hp_sdc.ibf && limit++ < 20)
		goto anew;

 done:
	if (hp_sdc.wcurr >= 0)
		tasklet_schedule(&hp_sdc.task);
	write_unlock(&hp_sdc.lock);

	return 0;
}


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/******* Functions called in either user or kernel context ****/



int __hp_sdc_enqueue_transaction(hp_sdc_transaction *this)
{
	int i;

	if (this == NULL) {
		BUG();
		return -EINVAL;
	}

	/* Can't have same transaction on queue twice */
	for (i = 0; i < HP_SDC_QUEUE_LEN; i++)
		if (hp_sdc.tq[i] == this)
			goto fail;

	this->actidx = 0;
	this->idx = 1;

	/* Search for empty slot */
	for (i = 0; i < HP_SDC_QUEUE_LEN; i++)
		if (hp_sdc.tq[i] == NULL) {
			hp_sdc.tq[i] = this;
			tasklet_schedule(&hp_sdc.task);
			return 0;
		}

	printk(KERN_WARNING PREFIX "No free slot to add transaction.\n");
	return -EBUSY;

 fail:
	printk(KERN_WARNING PREFIX "Transaction add failed: transaction already queued?\n");
	return -EINVAL;
}


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int hp_sdc_enqueue_transaction(hp_sdc_transaction *this) {
	unsigned long flags;
	int ret;

	write_lock_irqsave(&hp_sdc.lock, flags);
	ret = __hp_sdc_enqueue_transaction(this);
	write_unlock_irqrestore(&hp_sdc.lock,flags);

	return ret;
}


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int hp_sdc_dequeue_transaction(hp_sdc_transaction *this)
{
	unsigned long flags;
	int i;

	write_lock_irqsave(&hp_sdc.lock, flags);

	/* TODO: don't remove it if it's not done. */

	for (i = 0; i < HP_SDC_QUEUE_LEN; i++)
		if (hp_sdc.tq[i] == this)
			hp_sdc.tq[i] = NULL;

	write_unlock_irqrestore(&hp_sdc.lock, flags);
	return 0;
}




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/********************** User context functions **************************/



int hp_sdc_request_timer_irq(hp_sdc_irqhook *callback)
{
	if (callback == NULL || hp_sdc.dev == NULL)
		return -EINVAL;

	write_lock_irq(&hp_sdc.hook_lock);
	if (hp_sdc.timer != NULL) {
		write_unlock_irq(&hp_sdc.hook_lock);
		return -EBUSY;
	}

	hp_sdc.timer = callback;
	/* Enable interrupts from the timers */
	hp_sdc.im &= ~HP_SDC_IM_FH;
        hp_sdc.im &= ~HP_SDC_IM_PT;
	hp_sdc.im &= ~HP_SDC_IM_TIMERS;
	hp_sdc.set_im = 1;
	write_unlock_irq(&hp_sdc.hook_lock);

	tasklet_schedule(&hp_sdc.task);

	return 0;
}


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int hp_sdc_request_hil_irq(hp_sdc_irqhook *callback)
{
	if (callback == NULL || hp_sdc.dev == NULL)
		return -EINVAL;

	write_lock_irq(&hp_sdc.hook_lock);
	if (hp_sdc.hil != NULL) {
		write_unlock_irq(&hp_sdc.hook_lock);
		return -EBUSY;
	}

	hp_sdc.hil = callback;
	hp_sdc.im &= ~(HP_SDC_IM_HIL | HP_SDC_IM_RESET);
	hp_sdc.set_im = 1;
	write_unlock_irq(&hp_sdc.hook_lock);

	tasklet_schedule(&hp_sdc.task);

	return 0;
}


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int hp_sdc_request_cooked_irq(hp_sdc_irqhook *callback)
{
	if (callback == NULL || hp_sdc.dev == NULL)
		return -EINVAL;

	write_lock_irq(&hp_sdc.hook_lock);
	if (hp_sdc.cooked != NULL) {
		write_unlock_irq(&hp_sdc.hook_lock);
		return -EBUSY;
	}

	/* Enable interrupts from the HIL MLC */
	hp_sdc.cooked = callback;
	hp_sdc.im