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// 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);
}
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