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

Frank Li
2024-10-29T18:46:47Z

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>
---
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