Re: [PATCH v7 1/7] of: address: Add parent_bus_addr to struct of_pci_range

Manivannan Sadhasivam
2024-11-15T16:37:15Z

On Tue, Oct 29, 2024 at 12:36:34PM -0400, Frank Li wrote:
> Introduce field 'parent_bus_addr' in struct of_pci_range to retrieve parent
> bus address information.
>
> Refer to the diagram below to understand that the bus fabric in some
> systems (like i.MX8QXP) does not use a 1:1 address map between input and
> output.
>
> Currently, many controller drivers use .cpu_addr_fixup() callback hardcodes
> that translation in the code, e.g., "cpu_addr & CDNS_PLAT_CPU_TO_BUS_ADDR"
> (drivers/pci/controller/cadence/pcie-cadence-plat.c),
> "cpu_addr + BUS_IATU_OFFSET"(drivers/pci/controller/dwc/pcie-intel-gw.c),
> etc, even though those translations *should* be described via DT.
>
> The .cpu_addr_fixup() can be eliminated if DT correct reflect hardware
> behavior and driver 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>;
> ...
> };
> };
>
> 'parent_bus_addr' in struct of_pci_range can indicate above diagram internal
> address (IA) address information.
>
> Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
> Signed-off-by: Frank Li <Frank.Li@nxp.com>

Acked-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

- Mani

> ---
> Change from v5 to v7
> -none
>
> Change from v4 to v5
> - remove confused <0x5f000000 0x0 0x5f000000 0x21000000>
> - change address order to 7ff8_0000, 7ff0_0000, 7000_0000
> - In commit message use parent bus addres
>
> Change from v3 to v4
> - improve commit message by driver source code path.
>
> Change from v2 to v3
> - cpu_untranslate_addr -> parent_bus_addr
> - Add Rob's review tag
> I changed commit message base on Bjorn, if you have concern about review
> added tag, let me know.
>
> Change from v1 to v2
> - add parent_bus_addr in struct of_pci_range, instead adding new API.
> ---
> drivers/of/address.c | 2 ++
> include/linux/of_address.h | 1 +
> 2 files changed, 3 insertions(+)
>
> diff --git a/drivers/of/address.c b/drivers/of/address.c
> index 286f0c161e332..1a0229ee4e0b2 100644
> --- a/drivers/of/address.c
> +++ b/drivers/of/address.c
> @@ -811,6 +811,8 @@ struct of_pci_range *of_pci_range_parser_one(struct of_pci_range_parser *parser,
> else
> range->cpu_addr = of_translate_address(parser->node,
> parser->range + na);
> +
> + range->parent_bus_addr = of_read_number(parser->range + na, parser->pna);
> range->size = of_read_number(parser->range + parser->pna + na, ns);
>
> parser->range += np;
> diff --git a/include/linux/of_address.h b/include/linux/of_address.h
> index 26a19daf0d092..13dd79186d02c 100644
> --- a/include/linux/of_address.h
> +++ b/include/linux/of_address.h
> @@ -26,6 +26,7 @@ struct of_pci_range {
> u64 bus_addr;
> };
> u64 cpu_addr;
> + u64 parent_bus_addr;
> u64 size;
> u32 flags;
> };
>
> --
> 2.34.1
>

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