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hw/core/split-irq: Device that splits IRQ lines

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In some board or SoC models it is necessary to split a qemu_irq line
so that one input can feed multiple outputs.  We currently have
qemu_irq_split() for this, but that has several deficiencies:
 * it can only handle splitting a line into two
 * it unavoidably leaks memory, so it can't be used
   in a device that can be deleted

Implement a qdev device that encapsulates splitting of IRQs, with a
configurable number of outputs.  (This is in some ways the inverse of
the TYPE_OR_IRQ device.)

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20180220180325.29818-13-peter.maydell@linaro.org
This commit is contained in:
Peter Maydell 2018-03-02 10:45:38 +00:00
parent 4a151677a8
commit 5edb1b3fa9
4 changed files with 150 additions and 1 deletions
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57
include/hw/core/split-irq.h Normal file
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/*
* IRQ splitter device.
*
* Copyright (c) 2018 Linaro Limited.
* Written by Peter Maydell
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
/* This is a simple device which has one GPIO input line and multiple
* GPIO output lines. Any change on the input line is forwarded to all
* of the outputs.
*
* QEMU interface:
* + one unnamed GPIO input: the input line
* + N unnamed GPIO outputs: the output lines
* + QOM property "num-lines": sets the number of output lines
*/
#ifndef HW_SPLIT_IRQ_H
#define HW_SPLIT_IRQ_H
#include "hw/irq.h"
#include "hw/sysbus.h"
#include "qom/object.h"
#define TYPE_SPLIT_IRQ "split-irq"
#define MAX_SPLIT_LINES 16
typedef struct SplitIRQ SplitIRQ;
#define SPLIT_IRQ(obj) OBJECT_CHECK(SplitIRQ, (obj), TYPE_SPLIT_IRQ)
struct SplitIRQ {
DeviceState parent_obj;
qemu_irq out_irq[MAX_SPLIT_LINES];
uint16_t num_lines;
};
#endif