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 <20210913182550.264165-11-maz@kernel.org>
Date:   Mon, 13 Sep 2021 22:45:13 +0200
From:   "Sven Peter" <sven@svenpeter.dev>
To:     "Marc Zyngier" <maz@kernel.org>, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org
Cc:     "Bjorn Helgaas" <bhelgaas@google.com>,
        "Rob Herring" <robh+dt@kernel.org>,
        "Lorenzo Pieralisi" <lorenzo.pieralisi@arm.com>,
        =?UTF-8?Q?Krzysztof_Wilczy=C5=84ski?= <kw@linux.com>,
        "Alyssa Rosenzweig" <alyssa@rosenzweig.io>,
        "Stan Skowronek" <stan@corellium.com>,
        "Mark Kettenis" <kettenis@openbsd.org>,
        "Hector Martin" <marcan@marcan.st>,
        "Robin Murphy" <Robin.Murphy@arm.com>, kernel-team@android.com
Subject: =?UTF-8?Q?Re:_[PATCH_v3_10/10]_PCI:_apple:_Configure_RID_to_SID_mapper_o?=
 =?UTF-8?Q?n_device_addition?=
Content-Type: text/plain
Precedence: bulk


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@kernel.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.
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.


Sven