[mirror_ubuntu-jammy-kernel.git] / drivers / misc / ibmasm / event.c

// SPDX-License-Identifier: GPL-2.0-or-later

/*
 * IBM ASM Service Processor Device Driver
 *
 * Copyright (C) IBM Corporation, 2004
 *
 * Author: Max Asböck <amax@us.ibm.com>
 */

#include <linux/sched.h>
#include <linux/slab.h>
#include "ibmasm.h"
#include "lowlevel.h"

/*
 * ASM service processor event handling routines.
 *
 * Events are signalled to the device drivers through interrupts.
 * They have the format of dot commands, with the type field set to
 * sp_event.
 * The driver does not interpret the events, it simply stores them in a
 * circular buffer.
 */

static void wake_up_event_readers(struct service_processor *sp)
{
	struct event_reader *reader;

	list_for_each_entry(reader, &sp->event_buffer->readers, node)
                wake_up_interruptible(&reader->wait);
}

/*
 * receive_event
 * Called by the interrupt handler when a dot command of type sp_event is
 * received.
 * Store the event in the circular event buffer, wake up any sleeping
 * event readers.
 * There is no reader marker in the buffer, therefore readers are
 * responsible for keeping up with the writer, or they will lose events.
 */
void ibmasm_receive_event(struct service_processor *sp, void *data, unsigned int data_size)
{
	struct event_buffer *buffer = sp->event_buffer;
	struct ibmasm_event *event;
	unsigned long flags;

	data_size = min(data_size, IBMASM_EVENT_MAX_SIZE);

	spin_lock_irqsave(&sp->lock, flags);
	/* copy the event into the next slot in the circular buffer */
	event = &buffer->events[buffer->next_index];
	memcpy_fromio(event->data, data, data_size);
	event->data_size = data_size;
	event->serial_number = buffer->next_serial_number;

	/* advance indices in the buffer */
	buffer->next_index = (buffer->next_index + 1) % IBMASM_NUM_EVENTS;
	buffer->next_serial_number++;
	spin_unlock_irqrestore(&sp->lock, flags);

	wake_up_event_readers(sp);
}

static inline int event_available(struct event_buffer *b, struct event_reader *r)
{
	return (r->next_serial_number < b->next_serial_number);
}

/*
 * get_next_event
 * Called by event readers (initiated from user space through the file
 * system).
 * Sleeps until a new event is available.
 */
int ibmasm_get_next_event(struct service_processor *sp, struct event_reader *reader)
{
	struct event_buffer *buffer = sp->event_buffer;
	struct ibmasm_event *event;
	unsigned int index;
	unsigned long flags;

	reader->cancelled = 0;

	if (wait_event_interruptible(reader->wait,
			event_available(buffer, reader) || reader->cancelled))
		return -ERESTARTSYS;

	if (!event_available(buffer, reader))
		return 0;

	spin_lock_irqsave(&sp->lock, flags);

	index = buffer->next_index;
	event = &buffer->events[index];
	while (event->serial_number < reader->next_serial_number) {
		index = (index + 1) % IBMASM_NUM_EVENTS;
		event = &buffer->events[index];
	}
	memcpy(reader->data, event->data, event->data_size);
	reader->data_size = event->data_size;
	reader->next_serial_number = event->serial_number + 1;

	spin_unlock_irqrestore(&sp->lock, flags);

	return event->data_size;
}

void ibmasm_cancel_next_event(struct event_reader *reader)
{
        reader->cancelled = 1;
        wake_up_interruptible(&reader->wait);
}

void ibmasm_event_reader_register(struct service_processor *sp, struct event_reader *reader)
{
	unsigned long flags;

	reader->next_serial_number = sp->event_buffer->next_serial_number;
	init_waitqueue_head(&reader->wait);
	spin_lock_irqsave(&sp->lock, flags);
	list_add(&reader->node, &sp->event_buffer->readers);
	spin_unlock_irqrestore(&sp->lock, flags);
}

void ibmasm_event_reader_unregister(struct service_processor *sp, struct event_reader *reader)
{
	unsigned long flags;

	spin_lock_irqsave(&sp->lock, flags);
	list_del(&reader->node);
	spin_unlock_irqrestore(&sp->lock, flags);
}

int ibmasm_event_buffer_init(struct service_processor *sp)
{
	struct event_buffer *buffer;
	struct ibmasm_event *event;
	int i;

	buffer = kmalloc(sizeof(struct event_buffer), GFP_KERNEL);
	if (!buffer)
		return -ENOMEM;

	buffer->next_index = 0;
	buffer->next_serial_number = 1;

	event = buffer->events;
	for (i=0; i<IBMASM_NUM_EVENTS; i++, event++)
		event->serial_number = 0;

	INIT_LIST_HEAD(&buffer->readers);

	sp->event_buffer = buffer;

	return 0;
}

void ibmasm_event_buffer_exit(struct service_processor *sp)
{
	kfree(sp->event_buffer);
}
Commit	Line	Data
1a59d1b8	1	// SPDX-License-Identifier: GPL-2.0-or-later
1da177e4 LT	2
	3	/*
	4	* IBM ASM Service Processor Device Driver
	5	*
1da177e4 LT	6	* Copyright (C) IBM Corporation, 2004
1da177e4 LT	7	*
d36b6910	8	* Author: Max Asböck <amax@us.ibm.com>
1da177e4 LT	9	*/
1da177e4 LT	10
d43c36dc	11	#include <linux/sched.h>
5a0e3ad6	12	#include <linux/slab.h>
1da177e4	13	#include "ibmasm.h"
b8acb808	14	#include "lowlevel.h"
1da177e4 LT	15
	16	/*
	17	* ASM service processor event handling routines.
	18	*
	19	* Events are signalled to the device drivers through interrupts.
	20	* They have the format of dot commands, with the type field set to
	21	* sp_event.
	22	* The driver does not interpret the events, it simply stores them in a
	23	* circular buffer.
	24	*/
	25
1da177e4 LT	26	static void wake_up_event_readers(struct service_processor *sp)
	27	{
	28	struct event_reader *reader;
	29
	30	list_for_each_entry(reader, &sp->event_buffer->readers, node)
	31	wake_up_interruptible(&reader->wait);
	32	}
	33
63969cf2	34	/*
1da177e4 LT	35	* receive_event
	36	* Called by the interrupt handler when a dot command of type sp_event is
	37	* received.
	38	* Store the event in the circular event buffer, wake up any sleeping
	39	* event readers.
	40	* There is no reader marker in the buffer, therefore readers are
3a4e3678	41	* responsible for keeping up with the writer, or they will lose events.
3110dc7a	42	*/
1da177e4 LT	43	void ibmasm_receive_event(struct service_processor sp, void data, unsigned int data_size)
	44	{
	45	struct event_buffer *buffer = sp->event_buffer;
	46	struct ibmasm_event *event;
	47	unsigned long flags;
	48
	49	data_size = min(data_size, IBMASM_EVENT_MAX_SIZE);
	50
	51	spin_lock_irqsave(&sp->lock, flags);
	52	/* copy the event into the next slot in the circular buffer */
	53	event = &buffer->events[buffer->next_index];
b8acb808	54	memcpy_fromio(event->data, data, data_size);
1da177e4 LT	55	event->data_size = data_size;
	56	event->serial_number = buffer->next_serial_number;
	57
	58	/* advance indices in the buffer */
	59	buffer->next_index = (buffer->next_index + 1) % IBMASM_NUM_EVENTS;
	60	buffer->next_serial_number++;
	61	spin_unlock_irqrestore(&sp->lock, flags);
	62
	63	wake_up_event_readers(sp);
	64	}
	65
	66	static inline int event_available(struct event_buffer b, struct event_reader r)
	67	{
3110dc7a	68	return (r->next_serial_number < b->next_serial_number);
1da177e4 LT	69	}
1da177e4 LT	70
63969cf2	71	/*
1da177e4 LT	72	* get_next_event
1da177e4 LT	73	* Called by event readers (initiated from user space through the file
3110dc7a	74	* system).
1da177e4 LT	75	* Sleeps until a new event is available.
	76	*/
	77	int ibmasm_get_next_event(struct service_processor sp, struct event_reader reader)
	78	{
	79	struct event_buffer *buffer = sp->event_buffer;
	80	struct ibmasm_event *event;
	81	unsigned int index;
	82	unsigned long flags;
	83
b8acb808 MA	84	reader->cancelled = 0;
	85
	86	if (wait_event_interruptible(reader->wait,
	87	event_available(buffer, reader) \|\| reader->cancelled))
1da177e4 LT	88	return -ERESTARTSYS;
	89
	90	if (!event_available(buffer, reader))
	91	return 0;
	92
	93	spin_lock_irqsave(&sp->lock, flags);
	94
	95	index = buffer->next_index;
	96	event = &buffer->events[index];
	97	while (event->serial_number < reader->next_serial_number) {
	98	index = (index + 1) % IBMASM_NUM_EVENTS;
	99	event = &buffer->events[index];
	100	}
	101	memcpy(reader->data, event->data, event->data_size);
	102	reader->data_size = event->data_size;
	103	reader->next_serial_number = event->serial_number + 1;
	104
	105	spin_unlock_irqrestore(&sp->lock, flags);
	106
	107	return event->data_size;
	108	}
	109
b8acb808 MA	110	void ibmasm_cancel_next_event(struct event_reader *reader)
	111	{
	112	reader->cancelled = 1;
	113	wake_up_interruptible(&reader->wait);
	114	}
	115
1da177e4 LT	116	void ibmasm_event_reader_register(struct service_processor sp, struct event_reader reader)
	117	{
	118	unsigned long flags;
	119
	120	reader->next_serial_number = sp->event_buffer->next_serial_number;
	121	init_waitqueue_head(&reader->wait);
	122	spin_lock_irqsave(&sp->lock, flags);
	123	list_add(&reader->node, &sp->event_buffer->readers);
	124	spin_unlock_irqrestore(&sp->lock, flags);
	125	}
	126
	127	void ibmasm_event_reader_unregister(struct service_processor sp, struct event_reader reader)
	128	{
	129	unsigned long flags;
	130
1da177e4 LT	131	spin_lock_irqsave(&sp->lock, flags);
	132	list_del(&reader->node);
	133	spin_unlock_irqrestore(&sp->lock, flags);
	134	}
	135
	136	int ibmasm_event_buffer_init(struct service_processor *sp)
	137	{
	138	struct event_buffer *buffer;
	139	struct ibmasm_event *event;
	140	int i;
	141
	142	buffer = kmalloc(sizeof(struct event_buffer), GFP_KERNEL);
	143	if (!buffer)
f403f85f	144	return -ENOMEM;
1da177e4 LT	145
	146	buffer->next_index = 0;
	147	buffer->next_serial_number = 1;
	148
	149	event = buffer->events;
	150	for (i=0; i<IBMASM_NUM_EVENTS; i++, event++)
	151	event->serial_number = 0;
	152
	153	INIT_LIST_HEAD(&buffer->readers);
	154
	155	sp->event_buffer = buffer;
	156
	157	return 0;
	158	}
	159
	160	void ibmasm_event_buffer_exit(struct service_processor *sp)
	161	{
1da177e4 LT	162	kfree(sp->event_buffer);
1da177e4 LT	163	}