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hw/core/or-irq: Support more than 16 inputs to an OR gate

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For the IoTKit MPC support, we need to wire together the
interrupt outputs of 17 MPCs; this exceeds the current
value of MAX_OR_LINES. Increase MAX_OR_LINES to 32 (which
should be enough for anyone).

The tricky part is retaining the migration compatibility for
existing OR gates; we add a subsection which is only used
for larger OR gates, and define it such that we can freely
increase MAX_OR_LINES in future (or even move to a dynamically
allocated levels[] array without an upper size limit) without
breaking compatibility.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-id: 20180604152941.20374-10-peter.maydell@linaro.org
This commit is contained in:
Peter Maydell 2018-06-15 14:57:14 +01:00
parent 95f875654a
commit f81804a52b
2 changed files with 41 additions and 3 deletions
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39
hw/core/or-irq.c
View file

@ -66,14 +66,49 @@ static void or_irq_init(Object *obj)
qdev_init_gpio_out(DEVICE(obj), &s->out_irq, 1);
}
/* The original version of this device had a fixed 16 entries in its
* VMState array; devices with more inputs than this need to
* migrate the extra lines via a subsection.
* The subsection migrates as much of the levels[] array as is needed
* (including repeating the first 16 elements), to avoid the awkwardness
* of splitting it in two to meet the requirements of VMSTATE_VARRAY_UINT16.
*/
#define OLD_MAX_OR_LINES 16
#if MAX_OR_LINES < OLD_MAX_OR_LINES
#error MAX_OR_LINES must be at least 16 for migration compatibility
#endif
static bool vmstate_extras_needed(void *opaque)
{
qemu_or_irq *s = OR_IRQ(opaque);
return s->num_lines >= OLD_MAX_OR_LINES;
}
static const VMStateDescription vmstate_or_irq_extras = {
.name = "or-irq-extras",
.version_id = 1,
.minimum_version_id = 1,
.needed = vmstate_extras_needed,
.fields = (VMStateField[]) {
VMSTATE_VARRAY_UINT16_UNSAFE(levels, qemu_or_irq, num_lines, 0,
vmstate_info_bool, bool),
VMSTATE_END_OF_LIST(),
},
};
static const VMStateDescription vmstate_or_irq = {
.name = TYPE_OR_IRQ,
.version_id = 1,
.minimum_version_id = 1,
.fields = (VMStateField[]) {
VMSTATE_BOOL_ARRAY(levels, qemu_or_irq, MAX_OR_LINES),
VMSTATE_BOOL_SUB_ARRAY(levels, qemu_or_irq, 0, OLD_MAX_OR_LINES),
VMSTATE_END_OF_LIST(),
}
},
.subsections = (const VMStateDescription*[]) {
&vmstate_or_irq_extras,
NULL
},
};
static Property or_irq_properties[] = {

5
include/hw/or-irq.h
View file

@ -31,7 +31,10 @@
#define TYPE_OR_IRQ "or-irq"
#define MAX_OR_LINES 16
/* This can safely be increased if necessary without breaking
* migration compatibility (as long as it remains greater than 15).
*/
#define MAX_OR_LINES 32
typedef struct OrIRQState qemu_or_irq;