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Re: [PATCH] hw/misc: Add an iBT device model


From: Cédric Le Goater
Subject: Re: [PATCH] hw/misc: Add an iBT device model
Date: Tue, 28 Sep 2021 19:54:26 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.1.0

On 9/24/21 20:43, Titus Rwantare wrote:
On Fri, 24 Sept 2021 at 03:55, Cédric Le Goater <clg@kaod.org> wrote:

Hello Titus,

On 9/24/21 10:42, Philippe Mathieu-Daudé wrote:
On 9/24/21 01:48, Titus Rwantare wrote:
Hello all,

I'd like some clarification on how the following code transfers irqs
back and forth:
b/hw/arm/aspeed_soc.c
+    /* iBT */
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->ibt), errp)) {
+        return;
+    }
+    memory_region_add_subregion(&s->lpc.iomem,
+                   sc->memmap[ASPEED_DEV_IBT] - sc->memmap[ASPEED_DEV_LPC],
+                   &s->ibt.iomem);
+    sysbus_connect_irq(SYS_BUS_DEVICE(&s->lpc), 1 + aspeed_lpc_ibt,


The iBT device IRQ is connected to a subdevice irq of the LPC device.
See aspeed_lpc_realize(). And triggered in aspeed_lpc_set_irq()

Yes, that side makes sense. I tried to get at that irq from
aspeed_ibt.c as follows:

qemu_irq_lower(ibt->lpc->subdevice_irqs[aspeed_lpc_ibt]); // or raise

static void aspeed_ibt_realize(DeviceState *dev, Error **errp)
{
AspeedIBTState *ibt = ASPEED_IBT(dev);
SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
IPMIInterface *ii = IPMI_INTERFACE(dev);
ibt->lpc = ASPEED_LPC(dev);
...

but this doesn't work and maybe I'm misusing the dynamic cast?

+                       qdev_get_gpio_in(DEVICE(&s->lpc), aspeed_lpc_ibt));
}

and

hw/misc/aspeed_ibt.c
+static void aspeed_ibt_realize(DeviceState *dev, Error **errp)
+{
+    SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
+    AspeedIBTState *ibt = ASPEED_IBT(dev);
...
+
+    sysbus_init_irq(sbd, &ibt->irq);

I ask because the code in aspeed_soc.c seems to connect to the
lpc->subdevice_irqs[aspeed_lpc_ibt], initialised on
hw/misc/aspeed_lpc.c:408.
I noticed that bmc firmware running in qemu was checking the BT_CTRL
register less frequently than I'd like while editing this patch to use
the IPMIInterface.

OK.

This might be a problem in aspeed_ibt_update_irq(). This patch is
an experiment from some few years ago. It still works good enough
for the witherspoon-bmc and powernv9 machines for simple IPMI
commands: fru, sdr, lan, power off (to be checked).

Could you share your BMC and host command line ?


Host:
-chardev socket,id=ipmichr1,host=localhost,port=9999,reconnect=10 \
-device ipmi-bmc-extern,chardev=ipmichr1,id=bmc0 \
-device isa-ipmi-bt,bmc=bmc0,irq=10 -nodefaults

BMC:
-chardev socket,id=ipmichr1,host=localhost,port=9999,server=on,wait=off \
-device ipmi-host-extern,chardev=ipmichr1,responder=/machine/soc/ibt

This looks correct.

But for this to work you need Hao's patch as well: [PATCH 7/8]
hw/ipmi: Add an IPMI external host device.
Is it based on my aspeed branch which contains the iBT model ?
Could you send the patchset as an RFC maybe ?


Thanks,

C.





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