Hi Mark,
On Sun, 26 Sept 2021 at 14:53, Mark Kettenis mark.kettenis@xs4all.nl wrote:
From: Simon Glass sjg@chromium.org Date: Mon, 20 Sep 2021 19:11:25 -0600
Hi Simon,
[..]
+static int apple_dart_bind(struct udevice *dev) +{
void *base;int sid, i;base = dev_read_addr_ptr(dev);if (!base)return -EINVAL;u32 params2 = readl(base + DART_PARAMS2);if (params2 & DART_PARAMS2_BYPASS_SUPPORT) {for (sid = 0; sid < 16; sid++) {writel(DART_TCR_BYPASS_DART | DART_TCR_BYPASS_DAPF,base + DART_TCR(sid));for (i = 0; i < 4; i++)writel(0, base + DART_TTBR(sid, i));}}Not allowed hardware access in bind(). Can this more to probe() ?
Well, I need to make sure that this happens before other drivers get probed (in particular the xhci-dwc3 driver). Is there a better mechanism to achieve that?
If those drivers have something in the DT indicating that they need this, then you can add a uclass_get_device_by_phandle() in those drivers.
Yes, there is an "iommus" property that points at the IOMMU. This is a standard property and I think it would make sense to have the core device probing code handle it in a way similar to how "power-domains" is handled. That way we don't have to add IOMMU hooks into each and every driver.
OK.
If not, then you can probe all the DART devices with uclass_probe_all().
Having said that, I see you are using UCLASS_MISC. I suspect this should have its own UCLASS_IOMMU.
So here is a proof-of-concept diff to add UCLASS_IOMMU. This deliberately does not yet introduce driver ops yet; coming up with something sensible there needs a bit more thought. For USB support all I need is for the probe function to put the IOMMU in bypass mode, so that is what's implemented here.
Does this look reasonable? I'll split this up eventually into a commit that adds UCLASS_IOMMU and a commit that adds the apple_dart driver.
Yes from a quick look. Remember for the IOMMU uclass to add a sandbox test, even though for now it will only probe the driver since there are no ops.
Also you don't need the #if in iommu-uclass.c as the linked will garbage-collect it.
Regards, Simon