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Frank Li
4dbf0155df
Add a new field called 'parent_bus_addr' to struct of_pci_range to use
when retrieving parent bus address information.
Refer to the diagram below to better understand that the bus fabric in
some systems (like i.MX8QXP) does not always use a 1:1 address map
between input and output.
Currently, many controller drivers use the cpu_addr_fixup() callback
that would often hardcode address translation directly in the code, e.g.,
"cpu_addr & CDNS_PLAT_CPU_TO_BUS_ADDR" or "cpu_addr + BUS_IATU_OFFSET",
etc., even though those translations *should* be described via DT.
However, the cpu_addr_fixup() can be eliminated if DT correctly reflects
hardware behavior and drivers use 'parent_bus_addr' in struct of_pci_range.
┌─────────┐ ┌────────────┐
┌─────┐ │ │ IA: 0x8ff8_0000 │ │
│ CPU ├───►│ ┌────►├─────────────────┐ │ PCI │
└─────┘ │ │ │ IA: 0x8ff0_0000 │ │ │
CPU Addr │ │ ┌─►├─────────────┐ │ │ Controller │
0x7ff8_0000─┼───┘ │ │ │ │ │ │
│ │ │ │ │ │ │ PCI Addr
0x7ff0_0000─┼──────┘ │ │ └──► IOSpace ─┼────────────►
│ │ │ │ │ 0
0x7000_0000─┼────────►├─────────┐ │ │ │
└─────────┘ │ └──────► CfgSpace ─┼────────────►
BUS Fabric │ │ │ 0
│ │ │
└──────────► MemSpace ─┼────────────►
IA: 0x8000_0000 │ │ 0x8000_0000
└────────────┘
bus@5f000000 {
compatible = "simple-bus";
#address-cells = <1>;
#size-cells = <1>;
ranges = <0x80000000 0x0 0x70000000 0x10000000>;
pcie@5f010000 {
compatible = "fsl,imx8q-pcie";
reg = <0x5f010000 0x10000>, <0x8ff00000 0x80000>;
reg-names = "dbi", "config";
#address-cells = <3>;
#size-cells = <2>;
device_type = "pci";
bus-range = <0x00 0xff>;
ranges = <0x81000000 0 0x00000000 0x8ff80000 0 0x00010000>,
<0x82000000 0 0x80000000 0x80000000 0 0x0ff00000>;
...
};
};
In the diagram above, the 'parent_bus_addr' field in struct of_pci_range
can indicate internal address (IA) address information.
Link: https://lore.kernel.org/r/20241119-pci_fixup_addr-v8-1-c4bfa5193288@nxp.com
Signed-off-by: Frank Li <Frank.Li@nxp.com>
[kwilczynski: commit log]
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Acked-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.