From faf7c6de34fb8eaa566726cc658ba5ad81fb32af Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Mon, 3 Aug 2020 17:55:03 +0100 Subject: [PATCH] include/hw/irq.h: New function qemu_irq_is_connected() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Reviewed-by: Philippe Mathieu-Daudé Reviewed-by: Alistair Francis Message-id: 20200728103744.6909-2-peter.maydell@linaro.org --- include/hw/irq.h | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) 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; +} + #endif