1// SPDX-License-Identifier: GPL-2.0-or-later
2
3/*
4 * IBM ASM Service Processor Device Driver
5 *
6 * Copyright (C) IBM Corporation, 2004
7 *
8 * Author: Max Asb��ck <amax@us.ibm.com>
9 */
10
11#include <linux/sched.h>
12#include <linux/slab.h>
13#include "ibmasm.h"
14#include "lowlevel.h"
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
26static 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
34/*
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
41 * responsible for keeping up with the writer, or they will lose events.
42 */
43void 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];
54	memcpy_fromio(event->data, data, data_size);
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
66static inline int event_available(struct event_buffer *b, struct event_reader *r)
67{
68	return (r->next_serial_number < b->next_serial_number);
69}
70
71/*
72 * get_next_event
73 * Called by event readers (initiated from user space through the file
74 * system).
75 * Sleeps until a new event is available.
76 */
77int 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
84	reader->cancelled = 0;
85
86	if (wait_event_interruptible(reader->wait,
87			event_available(buffer, reader) || reader->cancelled))
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
110void ibmasm_cancel_next_event(struct event_reader *reader)
111{
112        reader->cancelled = 1;
113        wake_up_interruptible(&reader->wait);
114}
115
116void 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
127void ibmasm_event_reader_unregister(struct service_processor *sp, struct event_reader *reader)
128{
129	unsigned long flags;
130
131	spin_lock_irqsave(&sp->lock, flags);
132	list_del(&reader->node);
133	spin_unlock_irqrestore(&sp->lock, flags);
134}
135
136int 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)
144		return -ENOMEM;
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
160void ibmasm_event_buffer_exit(struct service_processor *sp)
161{
162	kfree(sp->event_buffer);
163}
164