On Fri, 18 Oct 2024 at 17:05, Daniel P. Berrangé <berra...@redhat.com> wrote: > > On Fri, Oct 18, 2024 at 04:38:24PM +0100, Peter Maydell wrote: > > On Thu, 10 Oct 2024 at 18:39, Octavian Purdila <ta...@google.com> wrote: > > > > > > From: Valentin Ghita <valentingh...@google.com> > > > > > > Add option to allow for connecting device GPIOs. This is useful when > > > adding a peripheral device from the command line which uses an > > > interrupt. > > > > > > It takes the following options: > > > > > > * in-dev-path, out-dev-path - required, the device canonical object > > > path (e.g. /machine/peripheral-anon/device[0], > > > /machine/iotkit/cluster0/armv7m0) for the devices that should have > > > their in <-> out GPIOs connected > > > > > > * in-gpio-name, out-gpio-name - optional, the name of the GPIO list; > > > if not specified, the unnamed GPIO list is used > > > > > > * in-gpio-index, out-gpio-index - optional, the index in the GPIO list > > > that identifies the GPIO to be used; if not specified 0 (the first > > > GPIO in the list) is used > > > > > > Usage example: > > > > > > # add the tmp105 sensor and connects its irq line to the CPU > > > qemu-system-arm \ > > > --machine mps2-an505 \ > > > --device tmp105,bus=/versatile_i2c/i2c,address=0x50 \ > > > --connect-gpios out-dev-path=/machine/peripheral-anon/device[0],\ > > > in-dev-path=/machine/iotkit/cluster0/armv7m0,in-gpio-index=100 > > > > > > This seems to be moving down the path towards "create and > > wire up machines on the command line". We shouldn't > > be doing that ad-hoc with one small commandline option > > at a time, we should be doing it with a coherent plan. > > Yeah, as a general rule, adding new CLI args is pretty undesirable. > To avoid that we could utilize QOM for representing data: > eg a "gpio-connection" object: > > --object gpio-connection,out-dev-path=/machine/peripheral-anon/device[0],\ > in-dev-path=/machine/iotkit/cluster0/armv7m0,in-gpio-index=100 > > this would be OK if we're fine with some code somewhere that iterates > over the 'gpio-connection' object instances performing the wiring.
Maybe, but as I say we would want an overall design for this, not a single "well this happens to let this one user do this one specific thing" approach. At the moment our design is "QEMU command line options are for doing the equivalent of plugging in PCI cards into slots, not for the equivalent of soldering chips onto boards". And in that view of the world "link this gpio line from the tmp105 up to the armv7m interrupt controller" is not something to do on the command line, because it's definitely soldering wires. So for current QEMU the answer is "if the AN505 has a tmp105 sensor, we should be creating it in the C code for the machine, and if it doesn't then we don't support creating it on the command line". thanks -- PMM
