From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1ILMsy-0004yn-IS for qemu-devel@nongnu.org; Wed, 15 Aug 2007 13:42:24 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1ILMsv-0004uf-Rt for qemu-devel@nongnu.org; Wed, 15 Aug 2007 13:42:24 -0400 Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1ILMsv-0004uU-IF for qemu-devel@nongnu.org; Wed, 15 Aug 2007 13:42:21 -0400 Received: from mail.codesourcery.com ([65.74.133.4]) by monty-python.gnu.org with esmtps (TLS-1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1ILMsv-0004qt-3M for qemu-devel@nongnu.org; Wed, 15 Aug 2007 13:42:21 -0400 From: Paul Brook Date: Wed, 15 Aug 2007 18:42:16 +0100 References: <200708151822.56446.paul@codesourcery.com> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200708151842.17437.paul@codesourcery.com> Subject: [Qemu-devel] Re: Extending qemu_irq for reset signals Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Blue Swirl Cc: qemu-devel On Wednesday 15 August 2007, Blue Swirl wrote: > On 8/15/07, Paul Brook wrote: > > On Wednesday 15 August 2007, Paul Brook wrote: > > > > Okay, more explaining. This is the case where I'd want to use the > > > > signal: DMA controller ("upstream") can reset the slave device (ESP > > > > or Lance). DMA controller is created first and I also want to > > > > allocate reset signals at that point. Later when ESP is created, it > > > > should be possible to put ESP reset function and opaque data to the > > > > signal given but this is not possible with current API. Currently the > > > > DMA data would be passed to qemu_allocate_irqs. > > > > > > Ah, I see. The problem here is that you've got a cyclic dependency. For > > > DMA operations the ESP is in charge, so it makes sense to create the > > > subservient DMA device first. For the reset signals the DMA controller > > > is in charge so ideally you create the ESP device first. Because the > > > DMA interface is most complicated, it's probably takes precedence. > > > > > > I think you need to modify or use sparc32_dma_set_reset_data to take a > > > qemu_irq rather than a callback and opaque argument. Alternatively you > > > can move things around a bit and have the sun4m code do something > > > similar. i.e. the ESP and lance devices return the reset lines, then > > > the sun4m code pokes into the DMA device state. > > > > Oh, or you can pass a pointer to a qemu_irq from the DMA to the ESP and > > have the ESP poke its reset object in there that way. > > That's what I had in mind. Should I just extend the API for example with > /* Change the callback function and/or data */ > void qemu_irq_change(qemu_irq irq, qemu_irq_handler handler, > void *opaque); I'm not so keen on that. It breaks the nice property of having the IRQ lines owned by the receiver. I was thinking something like: struct DMAState { qemu_irq device_reset; }; qemu_irq *dma_init() { struct DMAState * d = malloc(); return &d->device_reset; } void esp_init(qemu_irq *resetp) { ESPState *d = malloc(); *reset = *qemu_irq_alloc(d, 1); } void sun4m_init() { qemu_irq *p = dma_init(); esp_init(p); } Paul