path: root/include/hw
diff options
authorPeter Maydell <peter.maydell@linaro.org>2020-08-03 17:55:03 +0100
committerPeter Maydell <peter.maydell@linaro.org>2020-08-03 17:55:03 +0100
commitfaf7c6de34fb8eaa566726cc658ba5ad81fb32af (patch)
tree345e882da13bdc0bfb228a045560777625c666df /include/hw
parente7e5a9595ab1136845c444141830fca0d2746a73 (diff)
include/hw/irq.h: New function qemu_irq_is_connected()
Mostly devices don't need to care whether one of their output qemu_irq lines is connected, because functions like qemu_set_irq() silently do nothing if there is nothing on the other end. However sometimes a device might want to implement default behaviour for the case where the machine hasn't wired the line up to anywhere. Provide a function qemu_irq_is_connected() that devices can use for this purpose. (The test is trivial but encapsulating it in a function makes it easier to see where we're doing it in case we need to change the implementation later.) Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org> Reviewed-by: Alistair Francis <alistair.francis@wdc.com> Message-id: 20200728103744.6909-2-peter.maydell@linaro.org
Diffstat (limited to 'include/hw')
1 files changed, 18 insertions, 0 deletions
diff --git a/include/hw/irq.h b/include/hw/irq.h
index 24ba0ece11..dc7abf199e 100644
--- a/include/hw/irq.h
+++ b/include/hw/irq.h
@@ -55,4 +55,22 @@ qemu_irq qemu_irq_split(qemu_irq irq1, qemu_irq irq2);
on an existing vector of qemu_irq. */
void qemu_irq_intercept_in(qemu_irq *gpio_in, qemu_irq_handler handler, int n);
+ * qemu_irq_is_connected: Return true if IRQ line is wired up
+ *
+ * If a qemu_irq has a device on the other (receiving) end of it,
+ * return true; otherwise return false.
+ *
+ * Usually device models don't need to care whether the machine model
+ * has wired up their outbound qemu_irq lines, because functions like
+ * qemu_set_irq() silently do nothing if there is nothing on the other
+ * end of the line. However occasionally a device model will want to
+ * provide default behaviour if its output is left floating, and
+ * it can use this function to identify when that is the case.
+ */
+static inline bool qemu_irq_is_connected(qemu_irq irq)
+ return irq != NULL;