[PATCH v9 4/7] PCI: dwc: Use devicetree 'ranges' property to get rid of cpu_addr_fixup() callback

Frank Li
2025-01-28T22:08:45Z

parent_bus_offset in resource_entry 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 Intermediate 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>
---
chagne from v8 to v9
- use resoure_entry parent_bus_offset to simple code logic
- add check for use_parent_dt_ranges and cpu_addr_fixup to make sure only
one set.

Change from v7 to v8
- Add dev_warning_once at dw_pcie_iatu_detect() to reminder
cpu_addr_fixup() user to correct their code
- use 'use_parent_dt_ranges' control enable use dt parent bus node ranges.
- rename dw_pcie_get_untranslate_addr to dw_pcie_get_parent_addr().
- of_property_read_reg() already have comments, so needn't add more.
- return actual err code from function

Change from v6 to v7
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 | 34 +++++++++++++++++++++--
drivers/pci/controller/dwc/pcie-designware.c | 9 ++++++
drivers/pci/controller/dwc/pcie-designware.h | 8 ++++++
3 files changed, 49 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index 1206b26bff3f2..a0c8e6f66ec4d 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -413,8 +413,10 @@ static void dw_pcie_host_request_msg_tlp_res(struct dw_pcie_rp *pp)
res->name = "msg";
res->flags = win->res->flags | IORESOURCE_BUSY;

- if (!devm_request_resource(pci->dev, win->res, res))
+ if (!devm_request_resource(pci->dev, win->res, res)) {
pp->msg_res = res;
+ pp->msg_parent_bus_offset = win->parent_bus_offset;
+ }
}
}

@@ -427,6 +429,7 @@ 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);
@@ -448,6 +451,26 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp)
if (IS_ERR(pp->va_cfg0_base))
return PTR_ERR(pp->va_cfg0_base);

+ if (pci->use_parent_dt_ranges) {
+ if (pci->ops->cpu_addr_fixup) {
+ dev_err(dev, "Use parent bus DT ranges, cpu_addr_fixup() must be removed\n");
+ return -EINVAL;
+ }
+
+ 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
+ * 'use_parent_dt_ranges' to true, The
+ * 'cpu_addr_fixup()' can be eliminated.
+ */
+ of_property_read_reg(np, index, &pp->cfg0_base, NULL);
+ }
+
bridge = devm_pci_alloc_host_bridge(dev, 0);
if (!bridge)
return -ENOMEM;
@@ -460,6 +483,9 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp)
pp->io_size = resource_size(win->res);
pp->io_bus_addr = win->res->start - win->offset;
pp->io_base = pci_pio_to_address(win->res->start);
+ /* In case ranges in pci node provide wrong information */
+ if (pci->use_parent_dt_ranges)
+ pp->io_base -= win->parent_bus_offset;
}

/* Set default bus ops */
@@ -739,6 +765,10 @@ static int dw_pcie_iatu_setup(struct dw_pcie_rp *pp)
atu.parent_bus_addr = entry->res->start;
atu.pci_addr = entry->res->start - entry->offset;

+ /* In case ranges in pci node provide wrong information */
+ if (pci->use_parent_dt_ranges)
+ atu.parent_bus_addr -= entry->parent_bus_offset;
+
/* 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) -
@@ -902,7 +932,7 @@ static int dw_pcie_pme_turn_off(struct dw_pcie *pci)
atu.size = resource_size(pci->pp.msg_res);
atu.index = pci->pp.msg_atu_index;

- atu.parent_bus_addr = pci->pp.msg_res->start;
+ atu.parent_bus_addr = pci->pp.msg_res->start - pci->pp.msg_parent_bus_offset;

ret = dw_pcie_prog_outbound_atu(pci, &atu);
if (ret)
diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
index 9d0a5f75effcc..909b14986660c 100644
--- a/drivers/pci/controller/dwc/pcie-designware.c
+++ b/drivers/pci/controller/dwc/pcie-designware.c
@@ -841,6 +841,15 @@ void dw_pcie_iatu_detect(struct dw_pcie *pci)
pci->region_align = 1 << fls(min);
pci->region_limit = (max << 32) | (SZ_4G - 1);

+ if (pci->ops && pci->ops->cpu_addr_fixup) {
+ /*
+ * If the parent 'ranges' property in DT correctly describes
+ * the address translation, cpu_addr_fixup() callback is not
+ * needed.
+ */
+ dev_warn_once(pci->dev, "cpu_addr_fixup() usage detected. Please fix DT!\n");
+ }
+
dev_info(pci->dev, "iATU: unroll %s, %u ob, %u ib, align %uK, limit %lluG\n",
dw_pcie_cap_is(pci, IATU_UNROLL) ? "T" : "F",
pci->num_ob_windows, pci->num_ib_windows,
diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index ac23604c829f4..483911ab9e629 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -380,6 +380,7 @@ struct dw_pcie_rp {
bool use_atu_msg;
int msg_atu_index;
struct resource *msg_res;
+ resource_size_t msg_parent_bus_offset;
bool use_linkup_irq;
};

@@ -465,6 +466,13 @@ struct dw_pcie {
struct reset_control_bulk_data core_rsts[DW_PCIE_NUM_CORE_RSTS];
struct gpio_desc *pe_rst;
bool suspended;
+ /*
+ * This flag indicates that the vendor driver uses devicetree 'ranges'
+ * property to allow iATU to use the Intermediate Address (IA) for
+ * outbound mapping. Using this flag also avoids the usage of
+ * 'cpu_addr_fixup' callback implementation in the driver.
+ */
+ bool use_parent_dt_ranges;
};

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

--
2.34.1