Re: [Qemu-devel] [PATCH v1 08/16] qdev: gpio: Add API for intercepting an IRQ

[Alexander Graf <agraf@suse.de>]

On 04.08.14 03:55, Peter Crosthwaite wrote:
> To replace the old qemu_irq intercept API (which had users reaching
> into qdev private state for IRQs).
>
> Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
> ---
>
>   hw/core/qdev.c         | 25 +++++++++++++++++++++++++
>   include/hw/qdev-core.h |  2 ++
>   2 files changed, 27 insertions(+)
>
> diff --git a/hw/core/qdev.c b/hw/core/qdev.c
> index e6b2231..4cbf773 100644
> --- a/hw/core/qdev.c
> +++ b/hw/core/qdev.c
> @@ -412,6 +412,31 @@ void qdev_connect_gpio_out_named(DeviceState *dev, const char *name, int n,
>       g_free(propname);
>   }
>   
> +/* disconnect a GPIO ouput, returning the disconnected input (if any) */
> +
> +static qemu_irq qdev_disconnect_gpio_out_named(DeviceState *dev,
> +                                               const char *name, int n)
> +{
> +    char *propname = g_strdup_printf("%s[%d]",
> +                                     name ? name : "unnamed-gpio-out", n);
> +
> +    qemu_irq ret = (qemu_irq)object_property_get_link(OBJECT(dev), propname,
> +                                                      NULL);
> +    if (ret) {
> +        object_property_set_link(OBJECT(dev), NULL, propname, NULL);
> +    }
> +    g_free(propname);
> +    return ret;
> +}
> +
> +void qdev_intercept_gpio_out(DeviceState *dev, qemu_irq_handler handler,
> +                             const char *name, int n)
> +{
> +    qemu_irq disconnected = qdev_disconnect_gpio_out_named(dev, name, n);
> +    qemu_irq icpt = qemu_allocate_irq(handler, disconnected, n);

This means that we can't pass in any other opaque to the intercepting 
handler which sounds suboptimal to me. Can't we pass in a qemu_irq as 
parameter and a pointer to a field where we can store the disconnected 
qemu_irq?

Then the caller can allocate its own qemu_irq with all the opaque data 
it wants and just have the intercept function overwrite a single field 
in the passed down opaque.

Or you just return the disconnected qemu_irq. Then the caller can do 
whatever it likes with it, such as set icpt->opaque to it.


Alex