[PATCH v7 2/7] PCI: dwc: Using parent_bus_addr in of_range to eliminate cpu_addr_fixup()

Frank Li
2024-10-29T18:46:53Z

parent_bus_addr in struct of_range can indicate address information just
ahead of PCIe controller. Most system's bus fabric use 1:1 map between
input and output address. but some hardware like i.MX8QXP doesn't use 1:1
map. See below diagram:

┌─────────┐ ┌────────────┐
┌─────┐ │ │ 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>;
...
};
};

Term internal address (IA) here means the address just before PCIe
controller. After ATU use this IA instead CPU address, cpu_addr_fixup() can
be removed.

Signed-off-by: Frank Li <Frank.Li@nxp.com>
---
Add a resource_size_t parent_bus_addr local varible to fix 32bit build
error.
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202410291546.kvgEWJv7-lkp@intel.com/

Chagne from v5 to v6
-add comments for of_property_read_reg().

Change from v4 to v5
- remove confused 0x5f00_0000 range in sample dts.
- reorder address at above diagram.

Change from v3 to v4
- none

Change from v2 to v3
- %s/cpu_untranslate_addr/parent_bus_addr/g
- update diagram.
- improve commit message.

Change from v1 to v2
- update because patch1 change get untranslate address method.
- add using_dtbus_info in case break back compatibility for exited platform.
---
drivers/pci/controller/dwc/pcie-designware-host.c | 55 ++++++++++++++++++++++-
drivers/pci/controller/dwc/pcie-designware.h | 8 ++++
2 files changed, 62 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index 3e41865c72904..ea01b7bda0a76 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -418,6 +418,34 @@ static void dw_pcie_host_request_msg_tlp_res(struct dw_pcie_rp *pp)
}
}

+static int dw_pcie_get_untranslate_addr(struct dw_pcie *pci, resource_size_t pci_addr,
+ resource_size_t *i_addr)
+{
+ struct device *dev = pci->dev;
+ struct device_node *np = dev->of_node;
+ struct of_range_parser parser;
+ struct of_range range;
+ int ret;
+
+ if (!pci->using_dtbus_info) {
+ *i_addr = pci_addr;
+ return 0;
+ }
+
+ ret = of_range_parser_init(&parser, np);
+ if (ret)
+ return ret;
+
+ for_each_of_pci_range(&parser, &range) {
+ if (pci_addr == range.bus_addr) {
+ *i_addr = range.parent_bus_addr;
+ break;
+ }
+ }
+
+ return 0;
+}
+
int dw_pcie_host_init(struct dw_pcie_rp *pp)
{
struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
@@ -427,6 +455,7 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp)
struct resource_entry *win;
struct pci_host_bridge *bridge;
struct resource *res;
+ int index;
int ret;

raw_spin_lock_init(&pp->lock);
@@ -440,6 +469,20 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp)
pp->cfg0_size = resource_size(res);
pp->cfg0_base = res->start;

+ if (pci->using_dtbus_info) {
+ index = of_property_match_string(np, "reg-names", "config");
+ if (index < 0)
+ return -EINVAL;
+ /*
+ * Retrieve the parent bus address of PCI config space.
+ * If the parent bus ranges in the device tree provide
+ * the correct address conversion information, set
+ * 'using_dtbus_info' to true, The 'cpu_addr_fixup()'
+ * can be eliminated.
+ */
+ of_property_read_reg(np, index, &pp->cfg0_base, NULL);
+ }
+
pp->va_cfg0_base = devm_pci_remap_cfg_resource(dev, res);
if (IS_ERR(pp->va_cfg0_base))
return PTR_ERR(pp->va_cfg0_base);
@@ -462,6 +505,9 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp)
pp->io_base = pci_pio_to_address(win->res->start);
}

+ if (dw_pcie_get_untranslate_addr(pci, pp->io_bus_addr, &pp->io_base))
+ return -ENODEV;
+
/* Set default bus ops */
bridge->ops = &dw_pcie_ops;
bridge->child_ops = &dw_child_pcie_ops;
@@ -722,6 +768,8 @@ static int dw_pcie_iatu_setup(struct dw_pcie_rp *pp)

i = 0;
resource_list_for_each_entry(entry, &pp->bridge->windows) {
+ resource_size_t parent_bus_addr;
+
if (resource_type(entry->res) != IORESOURCE_MEM)
continue;

@@ -730,9 +778,14 @@ static int dw_pcie_iatu_setup(struct dw_pcie_rp *pp)

atu.index = i;
atu.type = PCIE_ATU_TYPE_MEM;
- atu.cpu_addr = entry->res->start;
+ parent_bus_addr = entry->res->start;
atu.pci_addr = entry->res->start - entry->offset;

+ if (dw_pcie_get_untranslate_addr(pci, entry->res->start, &parent_bus_addr))
+ return -EINVAL;
+
+ atu.cpu_addr = parent_bus_addr;
+
/* Adjust iATU size if MSG TLP region was allocated before */
if (pp->msg_res && pp->msg_res->parent == entry->res)
atu.size = resource_size(entry->res) -
diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index 347ab74ac35aa..f8067393ad35a 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -463,6 +463,14 @@ struct dw_pcie {
struct reset_control_bulk_data core_rsts[DW_PCIE_NUM_CORE_RSTS];
struct gpio_desc *pe_rst;
bool suspended;
+ /*
+ * Use device tree 'ranges' property of bus node instead using
+ * cpu_addr_fixup(). Some old platform dts 'ranges' in bus node may not
+ * reflect real hardware's behavior. In case break these platform back
+ * compatibility, add below flags. Set it true if dts already correct
+ * indicate bus fabric address convert.
+ */
+ bool using_dtbus_info;
};

#define to_dw_pcie_from_pp(port) container_of((port), struct dw_pcie, pp)

--
2.34.1