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Date: Tue, 14 Sep 2021 10:35:32 +0100
From: Marc Zyngier <maz@...nel.org>
To: "Sven Peter" <sven@...npeter.dev>
Cc: devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-pci@...r.kernel.org, "Bjorn Helgaas" <bhelgaas@...gle.com>,
"Rob Herring" <robh+dt@...nel.org>,
"Lorenzo Pieralisi" <lorenzo.pieralisi@....com>,
Krzysztof Wilczyński <kw@...ux.com>,
"Alyssa Rosenzweig" <alyssa@...enzweig.io>,
"Stan Skowronek" <stan@...ellium.com>,
"Mark Kettenis" <kettenis@...nbsd.org>,
"Hector Martin" <marcan@...can.st>,
"Robin Murphy" <Robin.Murphy@....com>, kernel-team@...roid.com
Subject: Re: [PATCH v3 10/10] PCI: apple: Configure RID to SID mapper on device addition
On Mon, 13 Sep 2021 21:45:13 +0100,
"Sven Peter" <sven@...npeter.dev> wrote:
>
>
>
> On Mon, Sep 13, 2021, at 20:25, Marc Zyngier wrote:
> > The Apple PCIe controller doesn't directly feed the endpoint's
> > Requester ID to the IOMMU (DART), but instead maps RIDs onto
> > Stream IDs (SIDs). The DART and the PCIe controller must thus
> > agree on the SIDs that are used for translation (by using
> > the 'iommu-map' property).
> >
> > For this purpose, parse the 'iommu-map' property each time a
> > device gets added, and use the resulting translation to configure
> > the PCIe RID-to-SID mapper. Similarily, remove the translation
> > if/when the device gets removed.
> >
> > This is all driven from a bus notifier which gets registered at
> > probe time. Hopefully this is the only PCI controller driver
> > in the whole system.
> >
> > Signed-off-by: Marc Zyngier <maz@...nel.org>
> > ---
> > drivers/pci/controller/pcie-apple.c | 158 +++++++++++++++++++++++++++-
> > 1 file changed, 156 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/pci/controller/pcie-apple.c
> > b/drivers/pci/controller/pcie-apple.c
> > index 76344223245d..68d71eabe708 100644
> > --- a/drivers/pci/controller/pcie-apple.c
> > +++ b/drivers/pci/controller/pcie-apple.c
> > @@ -23,8 +23,10 @@
> > #include <linux/iopoll.h>
> > #include <linux/irqchip/chained_irq.h>
> > #include <linux/irqdomain.h>
> > +#include <linux/list.h>
> > #include <linux/module.h>
> > #include <linux/msi.h>
> > +#include <linux/notifier.h>
> > #include <linux/of_irq.h>
> > #include <linux/pci-ecam.h>
> >
> > @@ -116,6 +118,8 @@
> > #define PORT_TUNSTAT_PERST_ACK_PEND BIT(1)
> > #define PORT_PREFMEM_ENABLE 0x00994
> >
> > +#define MAX_RID2SID 64
>
> Do these actually have 64 slots? I thought that was only for
> the Thunderbolt controllers and that these only had 16.
You are indeed right, and I blindly used the limit used in the
Correlium driver. Using entries from 16 onward result in a non booting
system. The registers do not fault though, and simply ignore writes. I
came up with an simple fix for this, see below.
> I never checked it myself though and it doesn't make much
> of a difference for now since only four different RIDs will
> ever be connected anyway.
Four? I guess the radios expose more than a single RID?
Thanks,
M.
diff --git a/drivers/pci/controller/pcie-apple.c b/drivers/pci/controller/pcie-apple.c
index 68d71eabe708..ec9e7abd2aca 100644
--- a/drivers/pci/controller/pcie-apple.c
+++ b/drivers/pci/controller/pcie-apple.c
@@ -148,6 +148,7 @@ struct apple_pcie_port {
struct irq_domain *domain;
struct list_head entry;
DECLARE_BITMAP( sid_map, MAX_RID2SID);
+ int sid_map_sz;
int idx;
};
@@ -495,12 +496,12 @@ static int apple_pcie_setup_refclk(struct apple_pcie *pcie,
return 0;
}
-static void apple_pcie_rid2sid_write(struct apple_pcie_port *port,
+static u32 apple_pcie_rid2sid_write(struct apple_pcie_port *port,
int idx, u32 val)
{
writel_relaxed(val, port->base + PORT_RID2SID(idx));
/* Read back to ensure completion of the write */
- (void)readl_relaxed(port->base + PORT_RID2SID(idx));
+ return readl_relaxed(port->base + PORT_RID2SID(idx));
}
static int apple_pcie_setup_port(struct apple_pcie *pcie,
@@ -557,9 +558,16 @@ static int apple_pcie_setup_port(struct apple_pcie *pcie,
if (ret)
return ret;
- /* Reset all RID/SID mappings */
- for (i = 0; i < MAX_RID2SID; i++)
+ /* Reset all RID/SID mappings, and check for RAZ/WI registers */
+ for (i = 0; i < MAX_RID2SID; i++) {
+ if (apple_pcie_rid2sid_write(port, i, 0xbad1d) != 0xbad1d)
+ break;
apple_pcie_rid2sid_write(port, i, 0);
+ }
+
+ dev_dbg(pcie->dev, "%pOF: %d RID/SID mapping entries\n", np, i);
+
+ port->sid_map_sz = i;
list_add_tail(&port->entry, &pcie->ports);
init_completion(&pcie->event);
@@ -667,7 +675,7 @@ static int apple_pcie_add_device(struct pci_dev *pdev)
return err;
mutex_lock(&port->pcie->lock);
- sid_idx = bitmap_find_free_region(port->sid_map, MAX_RID2SID, 0);
+ sid_idx = bitmap_find_free_region(port->sid_map, port->sid_map_sz, 0);
mutex_unlock(&port->pcie->lock);
if (sid_idx < 0)
@@ -696,7 +704,7 @@ static void apple_pcie_release_device(struct pci_dev *pdev)
mutex_lock(&port->pcie->lock);
- for_each_set_bit(idx, port->sid_map, MAX_RID2SID) {
+ for_each_set_bit(idx, port->sid_map, port->sid_map_sz) {
u32 val;
val = readl_relaxed(port->base + PORT_RID2SID(idx));
--
Without deviation from the norm, progress is not possible.
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