[PATCH 5/5] riscv: sophgo: dts: enable pcie for PioneerBox

[PATCH 5/5] riscv: sophgo: dts: enable pcie for PioneerBox

[Chen Wang]

From: Chen Wang <unicorn_wang@outlook.com>

Enable pcie controllers for PioneerBox, which uses SG2042 SoC.

Signed-off-by: Chen Wang <unicorn_wang@outlook.com>
---
 arch/riscv/boot/dts/sophgo/sg2042-milkv-pioneer.dts | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/arch/riscv/boot/dts/sophgo/sg2042-milkv-pioneer.dts b/arch/riscv/boot/dts/sophgo/sg2042-milkv-pioneer.dts
index a3f9d6f22566..746b9c3d254c 100644
--- a/arch/riscv/boot/dts/sophgo/sg2042-milkv-pioneer.dts
+++ b/arch/riscv/boot/dts/sophgo/sg2042-milkv-pioneer.dts
@@ -45,6 +45,18 @@ mcu: syscon@17 {
 	};
 };
 
+&pcie_rc0 {
+	status = "okay";
+};
+
+&pcie_rc1 {
+	status = "okay";
+};
+
+&pcie_rc2 {
+	status = "okay";
+};
+
 &sd {
 	bus-width = <4>;
 	no-sdio;
-- 
2.34.1


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[PATCH 0/5] Add PCIe support to Sophgo SG2042 SoC

[Chen Wang]

From: Chen Wang <unicorn_wang@outlook.com>

Sophgo's SG2042 SoC uses Cadence PCIe core to implement RC mode.

This is a completely rewritten PCIe driver for SG2042. It inherits
some previously submitted patch codes (not merged into the upstream
mainline), but the biggest difference is that the support for
compatibility with old 32-bit PCIe devices has been removed in this
new version. This is because after discussing with community users,
we felt that there was not much demand for support for old devices,
so we made a new design based on the simplified design and practical
needs. If someone really needs to play with old devices, we can provide
them with some necessary hack patches in the downstream repository.

Since the new design is quite different from the old code, I will
release it as a new patch series. The old patch series can be found in
here [old-series].

Note, regarding [2/5] of this patchset, this fix is introduced because
the pcie->ops pointer is not filled in SG2042 PCIe driver. This is not
a must-have parameter, if we use it w/o checking will cause a null
pointer access error during runtime.

Link: https://lore.kernel.org/linux-riscv/cover.1736923025.git.unicorn_wang@outlook.com/ [old-series]

This patchset is based on v6.17-rc1.

Thanks,
Chen

---

Chen Wang (5):
  dt-bindings: pci: Add Sophgo SG2042 PCIe host
  PCI: cadence: Fix NULL pointer error for ops
  PCI: sg2042: Add Sophgo SG2042 PCIe driver
  riscv: sophgo: dts: add pcie controllers for SG2042
  riscv: sophgo: dts: enable pcie for PioneerBox

 .../bindings/pci/sophgo,sg2042-pcie-host.yaml |  66 +++++++++
 .../boot/dts/sophgo/sg2042-milkv-pioneer.dts  |  12 ++
 arch/riscv/boot/dts/sophgo/sg2042.dtsi        |  66 +++++++++
 drivers/pci/controller/cadence/Kconfig        |  12 ++
 drivers/pci/controller/cadence/Makefile       |   1 +
 .../controller/cadence/pcie-cadence-host.c    |   2 +-
 drivers/pci/controller/cadence/pcie-cadence.c |   4 +-
 drivers/pci/controller/cadence/pcie-cadence.h |   6 +-
 drivers/pci/controller/cadence/pcie-sg2042.c  | 134 ++++++++++++++++++
 9 files changed, 297 insertions(+), 6 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/pci/sophgo,sg2042-pcie-host.yaml
 create mode 100644 drivers/pci/controller/cadence/pcie-sg2042.c


base-commit: 8f5ae30d69d7543eee0d70083daf4de8fe15d585
-- 
2.34.1


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[PATCH 1/5] dt-bindings: pci: Add Sophgo SG2042 PCIe host

[Chen Wang]

From: Chen Wang <unicorn_wang@outlook.com>

Add binding for Sophgo SG2042 PCIe host controller.

Signed-off-by: Chen Wang <unicorn_wang@outlook.com>
---
 .../bindings/pci/sophgo,sg2042-pcie-host.yaml | 66 +++++++++++++++++++
 1 file changed, 66 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/pci/sophgo,sg2042-pcie-host.yaml

diff --git a/Documentation/devicetree/bindings/pci/sophgo,sg2042-pcie-host.yaml b/Documentation/devicetree/bindings/pci/sophgo,sg2042-pcie-host.yaml
new file mode 100644
index 000000000000..2cca3d113d11
--- /dev/null
+++ b/Documentation/devicetree/bindings/pci/sophgo,sg2042-pcie-host.yaml
@@ -0,0 +1,66 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/pci/sophgo,sg2042-pcie-host.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Sophgo SG2042 PCIe Host (Cadence PCIe Wrapper)
+
+description:
+  Sophgo SG2042 PCIe host controller is based on the Cadence PCIe core.
+
+maintainers:
+  - Chen Wang <unicorn_wang@outlook.com>
+
+properties:
+  compatible:
+    const: sophgo,sg2042-pcie-host
+
+  reg:
+    maxItems: 2
+
+  reg-names:
+    items:
+      - const: reg
+      - const: cfg
+
+  vendor-id:
+    const: 0x1f1c
+
+  device-id:
+    const: 0x2042
+
+  msi-parent: true
+
+allOf:
+  - $ref: cdns-pcie-host.yaml#
+
+required:
+  - compatible
+  - reg
+  - reg-names
+  - vendor-id
+  - device-id
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    pcie@62000000 {
+      compatible = "sophgo,sg2042-pcie-host";
+      device_type = "pci";
+      reg = <0x62000000  0x00800000>,
+            <0x48000000  0x00001000>;
+      reg-names = "reg", "cfg";
+      #address-cells = <3>;
+      #size-cells = <2>;
+      ranges = <0x81000000 0 0x00000000 0xde000000 0 0x00010000>,
+               <0x82000000 0 0xd0400000 0xd0400000 0 0x0d000000>;
+      bus-range = <0x00 0xff>;
+      vendor-id = <0x1f1c>;
+      device-id = <0x2042>;
+      cdns,no-bar-match-nbits = <48>;
+      msi-parent = <&msi>;
+    };
-- 
2.34.1


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[PATCH 2/5] PCI: cadence: Fix NULL pointer error for ops

[Chen Wang]

From: Chen Wang <unicorn_wang@outlook.com>

ops of struct cdns_pcie may be NULL, direct use
will result in a null pointer error.

Add checking of pcie->ops before using it.

Fixes: 40d957e6f9eb ("PCI: cadence: Add support to start link and verify link status")
Signed-off-by: Chen Wang <unicorn_wang@outlook.com>
---
 drivers/pci/controller/cadence/pcie-cadence-host.c | 2 +-
 drivers/pci/controller/cadence/pcie-cadence.c      | 4 ++--
 drivers/pci/controller/cadence/pcie-cadence.h      | 6 +++---
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/controller/cadence/pcie-cadence-host.c b/drivers/pci/controller/cadence/pcie-cadence-host.c
index 59a4631de79f..fffd63d6665e 100644
--- a/drivers/pci/controller/cadence/pcie-cadence-host.c
+++ b/drivers/pci/controller/cadence/pcie-cadence-host.c
@@ -531,7 +531,7 @@ static int cdns_pcie_host_init_address_translation(struct cdns_pcie_rc *rc)
 	cdns_pcie_writel(pcie, CDNS_PCIE_AT_OB_REGION_PCI_ADDR1(0), addr1);
 	cdns_pcie_writel(pcie, CDNS_PCIE_AT_OB_REGION_DESC1(0), desc1);
 
-	if (pcie->ops->cpu_addr_fixup)
+	if (pcie->ops && pcie->ops->cpu_addr_fixup)
 		cpu_addr = pcie->ops->cpu_addr_fixup(pcie, cpu_addr);
 
 	addr0 = CDNS_PCIE_AT_OB_REGION_CPU_ADDR0_NBITS(12) |
diff --git a/drivers/pci/controller/cadence/pcie-cadence.c b/drivers/pci/controller/cadence/pcie-cadence.c
index 70a19573440e..61806bbd8aa3 100644
--- a/drivers/pci/controller/cadence/pcie-cadence.c
+++ b/drivers/pci/controller/cadence/pcie-cadence.c
@@ -92,7 +92,7 @@ void cdns_pcie_set_outbound_region(struct cdns_pcie *pcie, u8 busnr, u8 fn,
 	cdns_pcie_writel(pcie, CDNS_PCIE_AT_OB_REGION_DESC1(r), desc1);
 
 	/* Set the CPU address */
-	if (pcie->ops->cpu_addr_fixup)
+	if (pcie->ops && pcie->ops->cpu_addr_fixup)
 		cpu_addr = pcie->ops->cpu_addr_fixup(pcie, cpu_addr);
 
 	addr0 = CDNS_PCIE_AT_OB_REGION_CPU_ADDR0_NBITS(nbits) |
@@ -123,7 +123,7 @@ void cdns_pcie_set_outbound_region_for_normal_msg(struct cdns_pcie *pcie,
 	}
 
 	/* Set the CPU address */
-	if (pcie->ops->cpu_addr_fixup)
+	if (pcie->ops && pcie->ops->cpu_addr_fixup)
 		cpu_addr = pcie->ops->cpu_addr_fixup(pcie, cpu_addr);
 
 	addr0 = CDNS_PCIE_AT_OB_REGION_CPU_ADDR0_NBITS(17) |
diff --git a/drivers/pci/controller/cadence/pcie-cadence.h b/drivers/pci/controller/cadence/pcie-cadence.h
index 1d81c4bf6c6d..2f07ba661bda 100644
--- a/drivers/pci/controller/cadence/pcie-cadence.h
+++ b/drivers/pci/controller/cadence/pcie-cadence.h
@@ -468,7 +468,7 @@ static inline u32 cdns_pcie_ep_fn_readl(struct cdns_pcie *pcie, u8 fn, u32 reg)
 
 static inline int cdns_pcie_start_link(struct cdns_pcie *pcie)
 {
-	if (pcie->ops->start_link)
+	if (pcie->ops && pcie->ops->start_link)
 		return pcie->ops->start_link(pcie);
 
 	return 0;
@@ -476,13 +476,13 @@ static inline int cdns_pcie_start_link(struct cdns_pcie *pcie)
 
 static inline void cdns_pcie_stop_link(struct cdns_pcie *pcie)
 {
-	if (pcie->ops->stop_link)
+	if (pcie->ops && pcie->ops->stop_link)
 		pcie->ops->stop_link(pcie);
 }
 
 static inline bool cdns_pcie_link_up(struct cdns_pcie *pcie)
 {
-	if (pcie->ops->link_up)
+	if (pcie->ops && pcie->ops->link_up)
 		return pcie->ops->link_up(pcie);
 
 	return true;
-- 
2.34.1


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[PATCH 3/5] PCI: sg2042: Add Sophgo SG2042 PCIe driver

[Chen Wang]

From: Chen Wang <unicorn_wang@outlook.com>

Add support for PCIe controller in SG2042 SoC. The controller
uses the Cadence PCIe core programmed by pcie-cadence*.c. The
PCIe controller will work in host mode only.

Signed-off-by: Chen Wang <unicorn_wang@outlook.com>
---
 drivers/pci/controller/cadence/Kconfig       |  12 ++
 drivers/pci/controller/cadence/Makefile      |   1 +
 drivers/pci/controller/cadence/pcie-sg2042.c | 134 +++++++++++++++++++
 3 files changed, 147 insertions(+)
 create mode 100644 drivers/pci/controller/cadence/pcie-sg2042.c

diff --git a/drivers/pci/controller/cadence/Kconfig b/drivers/pci/controller/cadence/Kconfig
index 666e16b6367f..b1f1941d5208 100644
--- a/drivers/pci/controller/cadence/Kconfig
+++ b/drivers/pci/controller/cadence/Kconfig
@@ -42,6 +42,17 @@ config PCIE_CADENCE_PLAT_EP
 	  endpoint mode. This PCIe controller may be embedded into many
 	  different vendors SoCs.
 
+config PCIE_SG2042
+	bool "Sophgo SG2042 PCIe controller (host mode)"
+	depends on ARCH_SOPHGO || COMPILE_TEST
+	depends on OF
+	depends on PCI_MSI
+	select PCIE_CADENCE_HOST
+	help
+	  Say Y here if you want to support the Sophgo SG2042 PCIe platform
+	  controller in host mode. Sophgo SG2042 PCIe controller uses Cadence
+	  PCIe core.
+
 config PCI_J721E
 	tristate
 	select PCIE_CADENCE_HOST if PCI_J721E_HOST != n
@@ -67,4 +78,5 @@ config PCI_J721E_EP
 	  Say Y here if you want to support the TI J721E PCIe platform
 	  controller in endpoint mode. TI J721E PCIe controller uses Cadence PCIe
 	  core.
+
 endmenu
diff --git a/drivers/pci/controller/cadence/Makefile b/drivers/pci/controller/cadence/Makefile
index 9bac5fb2f13d..4df4456d9539 100644
--- a/drivers/pci/controller/cadence/Makefile
+++ b/drivers/pci/controller/cadence/Makefile
@@ -4,3 +4,4 @@ obj-$(CONFIG_PCIE_CADENCE_HOST) += pcie-cadence-host.o
 obj-$(CONFIG_PCIE_CADENCE_EP) += pcie-cadence-ep.o
 obj-$(CONFIG_PCIE_CADENCE_PLAT) += pcie-cadence-plat.o
 obj-$(CONFIG_PCI_J721E) += pci-j721e.o
+obj-$(CONFIG_PCIE_SG2042) += pcie-sg2042.o
diff --git a/drivers/pci/controller/cadence/pcie-sg2042.c b/drivers/pci/controller/cadence/pcie-sg2042.c
new file mode 100644
index 000000000000..fe434dc2967e
--- /dev/null
+++ b/drivers/pci/controller/cadence/pcie-sg2042.c
@@ -0,0 +1,134 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * pcie-sg2042 - PCIe controller driver for Sophgo SG2042 SoC
+ *
+ * Copyright (C) 2025 Sophgo Technology Inc.
+ * Copyright (C) 2025 Chen Wang <unicorn_wang@outlook.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/of.h>
+#include <linux/pci.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+
+#include "pcie-cadence.h"
+
+/*
+ * SG2042 only support 4-byte aligned access, so for the rootbus (i.e. to read
+ * the Root Port itself, read32 is required. For non-rootbus (i.e. to read
+ * the PCIe peripheral registers, supports 1/2/4 byte aligned access, so
+ * directly using read should be fine.
+ *
+ * The same is true for write.
+ */
+static int sg2042_pcie_config_read(struct pci_bus *bus, unsigned int devfn,
+				   int where, int size, u32 *value)
+{
+	if (pci_is_root_bus(bus))
+		return pci_generic_config_read32(bus, devfn, where, size,
+						 value);
+
+	return pci_generic_config_read(bus, devfn, where, size, value);
+}
+
+static int sg2042_pcie_config_write(struct pci_bus *bus, unsigned int devfn,
+				    int where, int size, u32 value)
+{
+	if (pci_is_root_bus(bus))
+		return pci_generic_config_write32(bus, devfn, where, size,
+						  value);
+
+	return pci_generic_config_write(bus, devfn, where, size, value);
+}
+
+static struct pci_ops sg2042_pcie_host_ops = {
+	.map_bus	= cdns_pci_map_bus,
+	.read		= sg2042_pcie_config_read,
+	.write		= sg2042_pcie_config_write,
+};
+
+static int sg2042_pcie_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct pci_host_bridge *bridge;
+	struct cdns_pcie *pcie;
+	struct cdns_pcie_rc *rc;
+	int ret;
+
+	pcie = devm_kzalloc(dev, sizeof(*pcie), GFP_KERNEL);
+	if (!pcie)
+		return -ENOMEM;
+
+	bridge = devm_pci_alloc_host_bridge(dev, sizeof(*rc));
+	if (!bridge) {
+		dev_err(dev, "Failed to alloc host bridge!\n");
+		return -ENOMEM;
+	}
+
+	bridge->ops = &sg2042_pcie_host_ops;
+
+	rc = pci_host_bridge_priv(bridge);
+	pcie = &rc->pcie;
+	pcie->dev = dev;
+
+	platform_set_drvdata(pdev, pcie);
+
+	pm_runtime_enable(dev);
+
+	ret = pm_runtime_get_sync(dev);
+	if (ret < 0) {
+		dev_err(dev, "pm_runtime_get_sync failed\n");
+		goto err_get_sync;
+	}
+
+	ret = cdns_pcie_init_phy(dev, pcie);
+	if (ret) {
+		dev_err(dev, "Failed to init phy!\n");
+		goto err_get_sync;
+	}
+
+	ret = cdns_pcie_host_setup(rc);
+	if (ret < 0) {
+		dev_err(dev, "Failed to setup host!\n");
+		goto err_host_setup;
+	}
+
+	return 0;
+
+err_host_setup:
+	cdns_pcie_disable_phy(pcie);
+
+err_get_sync:
+	pm_runtime_put(dev);
+	pm_runtime_disable(dev);
+
+	return ret;
+}
+
+static void sg2042_pcie_shutdown(struct platform_device *pdev)
+{
+	struct cdns_pcie *pcie = platform_get_drvdata(pdev);
+	struct device *dev = &pdev->dev;
+
+	cdns_pcie_disable_phy(pcie);
+
+	pm_runtime_put(dev);
+	pm_runtime_disable(dev);
+}
+
+static const struct of_device_id sg2042_pcie_of_match[] = {
+	{ .compatible = "sophgo,sg2042-pcie-host" },
+	{},
+};
+
+static struct platform_driver sg2042_pcie_driver = {
+	.driver = {
+		.name		= "sg2042-pcie",
+		.of_match_table	= sg2042_pcie_of_match,
+		.pm		= &cdns_pcie_pm_ops,
+	},
+	.probe		= sg2042_pcie_probe,
+	.shutdown	= sg2042_pcie_shutdown,
+};
+builtin_platform_driver(sg2042_pcie_driver);
-- 
2.34.1


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[PATCH 4/5] riscv: sophgo: dts: add pcie controllers for SG2042

[Chen Wang]

From: Chen Wang <unicorn_wang@outlook.com>

Add PCIe controller nodes in DTS for Sophgo SG2042.
Default they are disabled.

Signed-off-by: Chen Wang <unicorn_wang@outlook.com>
---
 arch/riscv/boot/dts/sophgo/sg2042.dtsi | 66 ++++++++++++++++++++++++++
 1 file changed, 66 insertions(+)

diff --git a/arch/riscv/boot/dts/sophgo/sg2042.dtsi b/arch/riscv/boot/dts/sophgo/sg2042.dtsi
index b3e4d3c18fdc..346aba5bd9bf 100644
--- a/arch/riscv/boot/dts/sophgo/sg2042.dtsi
+++ b/arch/riscv/boot/dts/sophgo/sg2042.dtsi
@@ -220,6 +220,72 @@ clkgen: clock-controller@7030012000 {
 			#clock-cells = <1>;
 		};
 
+		pcie_rc0: pcie@7060000000 {
+			compatible = "sophgo,sg2042-pcie-host";
+			device_type = "pci";
+			reg = <0x70 0x60000000  0x0 0x02000000>,
+			      <0x40 0x00000000  0x0 0x00001000>;
+			reg-names = "reg", "cfg";
+			linux,pci-domain = <0>;
+			#address-cells = <3>;
+			#size-cells = <2>;
+			ranges = <0x01000000 0x0  0xc0000000  0x40 0xc0000000  0x0 0x00400000>,
+				 <0x42000000 0x0  0xd0000000  0x40 0xd0000000  0x0 0x10000000>,
+				 <0x02000000 0x0  0xe0000000  0x40 0xe0000000  0x0 0x20000000>,
+				 <0x43000000 0x42 0x00000000  0x42 0x00000000  0x2 0x00000000>,
+				 <0x03000000 0x41 0x00000000  0x41 0x00000000  0x1 0x00000000>;
+			bus-range = <0x0 0xff>;
+			vendor-id = <0x1f1c>;
+			device-id = <0x2042>;
+			cdns,no-bar-match-nbits = <48>;
+			msi-parent = <&msi>;
+			status = "disabled";
+		};
+
+		pcie_rc1: pcie@7062000000 {
+			compatible = "sophgo,sg2042-pcie-host";
+			device_type = "pci";
+			reg = <0x70 0x62000000  0x0 0x00800000>,
+			      <0x48 0x00000000  0x0 0x00001000>;
+			reg-names = "reg", "cfg";
+			linux,pci-domain = <1>;
+			#address-cells = <3>;
+			#size-cells = <2>;
+			ranges = <0x01000000 0x0  0xc0800000  0x48 0xc0800000  0x0 0x00400000>,
+				 <0x42000000 0x0  0xd0000000  0x48 0xd0000000  0x0 0x10000000>,
+				 <0x02000000 0x0  0xe0000000  0x48 0xe0000000  0x0 0x20000000>,
+				 <0x03000000 0x49 0x00000000  0x49 0x00000000  0x1 0x00000000>,
+				 <0x43000000 0x4a 0x00000000  0x4a 0x00000000  0x2 0x00000000>;
+			bus-range = <0x0 0xff>;
+			vendor-id = <0x1f1c>;
+			device-id = <0x2042>;
+			cdns,no-bar-match-nbits = <48>;
+			msi-parent = <&msi>;
+			status = "disabled";
+		};
+
+		pcie_rc2: pcie@7062800000 {
+			compatible = "sophgo,sg2042-pcie-host";
+			device_type = "pci";
+			reg = <0x70 0x62800000  0x0 0x00800000>,
+			      <0x4c 0x00000000  0x0 0x00001000>;
+			reg-names = "reg", "cfg";
+			linux,pci-domain = <2>;
+			#address-cells = <3>;
+			#size-cells = <2>;
+			ranges = <0x01000000 0x0  0xc0c00000  0x4c 0xc0c00000  0x0 0x00400000>,
+				 <0x42000000 0x0  0xf8000000  0x4c 0xf8000000  0x0 0x04000000>,
+				 <0x02000000 0x0  0xfc000000  0x4c 0xfc000000  0x0 0x04000000>,
+				 <0x43000000 0x4e 0x00000000  0x4e 0x00000000  0x2 0x00000000>,
+				 <0x03000000 0x4d 0x00000000  0x4d 0x00000000  0x1 0x00000000>;
+			bus-range = <0x0 0xff>;
+			vendor-id = <0x1f1c>;
+			device-id = <0x2042>;
+			cdns,no-bar-match-nbits = <48>;
+			msi-parent = <&msi>;
+			status = "disabled";
+		};
+
 		clint_mswi: interrupt-controller@7094000000 {
 			compatible = "sophgo,sg2042-aclint-mswi", "thead,c900-aclint-mswi";
 			reg = <0x00000070 0x94000000 0x00000000 0x00004000>;
-- 
2.34.1


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[PATCH 5/5] riscv: sophgo: dts: enable pcie for PioneerBox

[Chen Wang]

From: Chen Wang <unicorn_wang@outlook.com>

Enable pcie controllers for PioneerBox, which uses SG2042 SoC.

Signed-off-by: Chen Wang <unicorn_wang@outlook.com>
---
 arch/riscv/boot/dts/sophgo/sg2042-milkv-pioneer.dts | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/arch/riscv/boot/dts/sophgo/sg2042-milkv-pioneer.dts b/arch/riscv/boot/dts/sophgo/sg2042-milkv-pioneer.dts
index ef3a602172b1..6574d8e0b369 100644
--- a/arch/riscv/boot/dts/sophgo/sg2042-milkv-pioneer.dts
+++ b/arch/riscv/boot/dts/sophgo/sg2042-milkv-pioneer.dts
@@ -128,6 +128,18 @@ uart0-rx-pins {
 	};
 };
 
+&pcie_rc0 {
+	status = "okay";
+};
+
+&pcie_rc1 {
+	status = "okay";
+};
+
+&pcie_rc2 {
+	status = "okay";
+};
+
 &sd {
 	pinctrl-0 = <&sd_cfg>;
 	pinctrl-names = "default";
-- 
2.34.1


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Re: [PATCH 3/5] PCI: sg2042: Add Sophgo SG2042 PCIe driver

[ALOK TIWARI]

On 8/28/2025 7:47 AM, Chen Wang wrote:
> From: Chen Wang <unicorn_wang@outlook.com>
> 
> Add support for PCIe controller in SG2042 SoC. The controller
> uses the Cadence PCIe core programmed by pcie-cadence*.c. The
> PCIe controller will work in host mode only.
> 
> Signed-off-by: Chen Wang <unicorn_wang@outlook.com>
> ---
>   drivers/pci/controller/cadence/Kconfig       |  12 ++
>   drivers/pci/controller/cadence/Makefile      |   1 +
>   drivers/pci/controller/cadence/pcie-sg2042.c | 134 +++++++++++++++++++
>   3 files changed, 147 insertions(+)
>   create mode 100644 drivers/pci/controller/cadence/pcie-sg2042.c
> 
> diff --git a/drivers/pci/controller/cadence/Kconfig b/drivers/pci/controller/cadence/Kconfig
> index 666e16b6367f..b1f1941d5208 100644
> --- a/drivers/pci/controller/cadence/Kconfig
> +++ b/drivers/pci/controller/cadence/Kconfig
> @@ -42,6 +42,17 @@ config PCIE_CADENCE_PLAT_EP
>   	  endpoint mode. This PCIe controller may be embedded into many
>   	  different vendors SoCs.
>   
> +config PCIE_SG2042
> +	bool "Sophgo SG2042 PCIe controller (host mode)"
> +	depends on ARCH_SOPHGO || COMPILE_TEST
> +	depends on OF
> +	depends on PCI_MSI
> +	select PCIE_CADENCE_HOST
> +	help
> +	  Say Y here if you want to support the Sophgo SG2042 PCIe platform
> +	  controller in host mode. Sophgo SG2042 PCIe controller uses Cadence
> +	  PCIe core.
> +
>   config PCI_J721E
>   	tristate
>   	select PCIE_CADENCE_HOST if PCI_J721E_HOST != n
> @@ -67,4 +78,5 @@ config PCI_J721E_EP
>   	  Say Y here if you want to support the TI J721E PCIe platform
>   	  controller in endpoint mode. TI J721E PCIe controller uses Cadence PCIe
>   	  core.
> +
>   endmenu
> diff --git a/drivers/pci/controller/cadence/Makefile b/drivers/pci/controller/cadence/Makefile
> index 9bac5fb2f13d..4df4456d9539 100644
> --- a/drivers/pci/controller/cadence/Makefile
> +++ b/drivers/pci/controller/cadence/Makefile
> @@ -4,3 +4,4 @@ obj-$(CONFIG_PCIE_CADENCE_HOST) += pcie-cadence-host.o
>   obj-$(CONFIG_PCIE_CADENCE_EP) += pcie-cadence-ep.o
>   obj-$(CONFIG_PCIE_CADENCE_PLAT) += pcie-cadence-plat.o
>   obj-$(CONFIG_PCI_J721E) += pci-j721e.o
> +obj-$(CONFIG_PCIE_SG2042) += pcie-sg2042.o
> diff --git a/drivers/pci/controller/cadence/pcie-sg2042.c b/drivers/pci/controller/cadence/pcie-sg2042.c
> new file mode 100644
> index 000000000000..fe434dc2967e
> --- /dev/null
> +++ b/drivers/pci/controller/cadence/pcie-sg2042.c
> @@ -0,0 +1,134 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * pcie-sg2042 - PCIe controller driver for Sophgo SG2042 SoC
> + *
> + * Copyright (C) 2025 Sophgo Technology Inc.
> + * Copyright (C) 2025 Chen Wang <unicorn_wang@outlook.com>
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/of.h>
> +#include <linux/pci.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
> +
> +#include "pcie-cadence.h"
> +
> +/*
> + * SG2042 only support 4-byte aligned access, so for the rootbus (i.e. to read

support -> supports

> + * the Root Port itself, read32 is required. For non-rootbus (i.e. to read
> + * the PCIe peripheral registers, supports 1/2/4 byte aligned access, so
> + * directly using read should be fine.
> + *
> + * The same is true for write.
[clip]
> +static int sg2042_pcie_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct pci_host_bridge *bridge;
> +	struct cdns_pcie *pcie;
> +	struct cdns_pcie_rc *rc;
> +	int ret;
> +
> +	pcie = devm_kzalloc(dev, sizeof(*pcie), GFP_KERNEL);
> +	if (!pcie)
> +		return -ENOMEM;
> +
> +	bridge = devm_pci_alloc_host_bridge(dev, sizeof(*rc));
> +	if (!bridge) {
> +		dev_err(dev, "Failed to alloc host bridge!\n");
> +		return -ENOMEM;
> +	}
> +
> +	bridge->ops = &sg2042_pcie_host_ops;
> +
> +	rc = pci_host_bridge_priv(bridge);
> +	pcie = &rc->pcie;
First, pcie is allocated and then reassigned to &rc->pcie,
which makes the initial allocation effectively leaked and unnecessary.

> +	pcie->dev = dev;
> +
> +	platform_set_drvdata(pdev, pcie);
> +
> +	pm_runtime_enable(dev);
> +
> +	ret = pm_runtime_get_sync(dev);
> +	if (ret < 0) {
> +		dev_err(dev, "pm_runtime_get_sync failed\n");
> +		goto err_get_sync;
> +	}
> +
> +	ret = cdns_pcie_init_phy(dev, pcie);
> +	if (ret) {
> +		dev_err(dev, "Failed to init phy!\n");
> +		goto err_get_sync;
> +	}
> +
> +	ret = cdns_pcie_host_setup(rc);
> +	if (ret < 0) {
> +		dev_err(dev, "Failed to setup host!\n");
> +		goto err_host_setup;
> +	}
> +
> +	return 0;
> +
> +err_host_setup:
> +	cdns_pcie_disable_phy(pcie);
> +
> +err_get_sync:
> +	pm_runtime_put(dev);
> +	pm_runtime_disable(dev);
> +
> +	return ret;
> +}


Thanks,
Alok

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Re: [PATCH 2/5] PCI: cadence: Fix NULL pointer error for ops

[Bjorn Helgaas]

On Thu, Aug 28, 2025 at 10:17:17AM +0800, Chen Wang wrote:
> From: Chen Wang <unicorn_wang@outlook.com>
> 
> ops of struct cdns_pcie may be NULL, direct use
> will result in a null pointer error.
> 
> Add checking of pcie->ops before using it.
> 
> Fixes: 40d957e6f9eb ("PCI: cadence: Add support to start link and verify link status")

Do you observe this NULL pointer dereference with an existing driver?

If this is only to make it possible to add a new driver that doesn't
supply a pcie->ops pointer, it doesn't need a Fixes: tag because
there's not a problem with existing drivers and this change would not
need to be backported.

If it *is* a problem with an existing driver, please point out which
one.

> Signed-off-by: Chen Wang <unicorn_wang@outlook.com>
> ---
>  drivers/pci/controller/cadence/pcie-cadence-host.c | 2 +-
>  drivers/pci/controller/cadence/pcie-cadence.c      | 4 ++--
>  drivers/pci/controller/cadence/pcie-cadence.h      | 6 +++---
>  3 files changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/pci/controller/cadence/pcie-cadence-host.c b/drivers/pci/controller/cadence/pcie-cadence-host.c
> index 59a4631de79f..fffd63d6665e 100644
> --- a/drivers/pci/controller/cadence/pcie-cadence-host.c
> +++ b/drivers/pci/controller/cadence/pcie-cadence-host.c
> @@ -531,7 +531,7 @@ static int cdns_pcie_host_init_address_translation(struct cdns_pcie_rc *rc)
>  	cdns_pcie_writel(pcie, CDNS_PCIE_AT_OB_REGION_PCI_ADDR1(0), addr1);
>  	cdns_pcie_writel(pcie, CDNS_PCIE_AT_OB_REGION_DESC1(0), desc1);
>  
> -	if (pcie->ops->cpu_addr_fixup)
> +	if (pcie->ops && pcie->ops->cpu_addr_fixup)
>  		cpu_addr = pcie->ops->cpu_addr_fixup(pcie, cpu_addr);
>  
>  	addr0 = CDNS_PCIE_AT_OB_REGION_CPU_ADDR0_NBITS(12) |
> diff --git a/drivers/pci/controller/cadence/pcie-cadence.c b/drivers/pci/controller/cadence/pcie-cadence.c
> index 70a19573440e..61806bbd8aa3 100644
> --- a/drivers/pci/controller/cadence/pcie-cadence.c
> +++ b/drivers/pci/controller/cadence/pcie-cadence.c
> @@ -92,7 +92,7 @@ void cdns_pcie_set_outbound_region(struct cdns_pcie *pcie, u8 busnr, u8 fn,
>  	cdns_pcie_writel(pcie, CDNS_PCIE_AT_OB_REGION_DESC1(r), desc1);
>  
>  	/* Set the CPU address */
> -	if (pcie->ops->cpu_addr_fixup)
> +	if (pcie->ops && pcie->ops->cpu_addr_fixup)
>  		cpu_addr = pcie->ops->cpu_addr_fixup(pcie, cpu_addr);
>  
>  	addr0 = CDNS_PCIE_AT_OB_REGION_CPU_ADDR0_NBITS(nbits) |
> @@ -123,7 +123,7 @@ void cdns_pcie_set_outbound_region_for_normal_msg(struct cdns_pcie *pcie,
>  	}
>  
>  	/* Set the CPU address */
> -	if (pcie->ops->cpu_addr_fixup)
> +	if (pcie->ops && pcie->ops->cpu_addr_fixup)
>  		cpu_addr = pcie->ops->cpu_addr_fixup(pcie, cpu_addr);
>  
>  	addr0 = CDNS_PCIE_AT_OB_REGION_CPU_ADDR0_NBITS(17) |
> diff --git a/drivers/pci/controller/cadence/pcie-cadence.h b/drivers/pci/controller/cadence/pcie-cadence.h
> index 1d81c4bf6c6d..2f07ba661bda 100644
> --- a/drivers/pci/controller/cadence/pcie-cadence.h
> +++ b/drivers/pci/controller/cadence/pcie-cadence.h
> @@ -468,7 +468,7 @@ static inline u32 cdns_pcie_ep_fn_readl(struct cdns_pcie *pcie, u8 fn, u32 reg)
>  
>  static inline int cdns_pcie_start_link(struct cdns_pcie *pcie)
>  {
> -	if (pcie->ops->start_link)
> +	if (pcie->ops && pcie->ops->start_link)
>  		return pcie->ops->start_link(pcie);
>  
>  	return 0;
> @@ -476,13 +476,13 @@ static inline int cdns_pcie_start_link(struct cdns_pcie *pcie)
>  
>  static inline void cdns_pcie_stop_link(struct cdns_pcie *pcie)
>  {
> -	if (pcie->ops->stop_link)
> +	if (pcie->ops && pcie->ops->stop_link)
>  		pcie->ops->stop_link(pcie);
>  }
>  
>  static inline bool cdns_pcie_link_up(struct cdns_pcie *pcie)
>  {
> -	if (pcie->ops->link_up)
> +	if (pcie->ops && pcie->ops->link_up)
>  		return pcie->ops->link_up(pcie);
>  
>  	return true;
> -- 
> 2.34.1
> 

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Re: [PATCH 3/5] PCI: sg2042: Add Sophgo SG2042 PCIe driver

[Chen Wang]

On 8/28/2025 7:18 PM, ALOK TIWARI wrote:
>
>
> On 8/28/2025 7:47 AM, Chen Wang wrote:
>> From: Chen Wang <unicorn_wang@outlook.com>
>>
[......]

>> +
>> +#include <linux/kernel.h>
>> +#include <linux/of.h>
>> +#include <linux/pci.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/pm_runtime.h>
>> +
>> +#include "pcie-cadence.h"
>> +
>> +/*
>> + * SG2042 only support 4-byte aligned access, so for the rootbus 
>> (i.e. to read
>
> support -> supports
Nice catch!
>
>> + * the Root Port itself, read32 is required. For non-rootbus (i.e. 
>> to read
>> + * the PCIe peripheral registers, supports 1/2/4 byte aligned 
>> access, so
>> + * directly using read should be fine.
>> + *
>> + * The same is true for write.
> [clip]
>> +static int sg2042_pcie_probe(struct platform_device *pdev)
>> +{
>> +    struct device *dev = &pdev->dev;
>> +    struct pci_host_bridge *bridge;
>> +    struct cdns_pcie *pcie;
>> +    struct cdns_pcie_rc *rc;
>> +    int ret;
>> +
>> +    pcie = devm_kzalloc(dev, sizeof(*pcie), GFP_KERNEL);
>> +    if (!pcie)
>> +        return -ENOMEM;
>> +
>> +    bridge = devm_pci_alloc_host_bridge(dev, sizeof(*rc));
>> +    if (!bridge) {
>> +        dev_err(dev, "Failed to alloc host bridge!\n");
>> +        return -ENOMEM;
>> +    }
>> +
>> +    bridge->ops = &sg2042_pcie_host_ops;
>> +
>> +    rc = pci_host_bridge_priv(bridge);
>> +    pcie = &rc->pcie;
> First, pcie is allocated and then reassigned to &rc->pcie,
> which makes the initial allocation effectively leaked and unnecessary.

My fault.

Thanks,

Chen

[......]

>
> Thanks,
> Alok

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Re: [PATCH 2/5] PCI: cadence: Fix NULL pointer error for ops

[Chen Wang]

On 8/29/2025 5:43 AM, Bjorn Helgaas wrote:
> On Thu, Aug 28, 2025 at 10:17:17AM +0800, Chen Wang wrote:
>> From: Chen Wang <unicorn_wang@outlook.com>
>>
>> ops of struct cdns_pcie may be NULL, direct use
>> will result in a null pointer error.
>>
>> Add checking of pcie->ops before using it.
>>
>> Fixes: 40d957e6f9eb ("PCI: cadence: Add support to start link and verify link status")
> Do you observe this NULL pointer dereference with an existing driver?
>
> If this is only to make it possible to add a new driver that doesn't
> supply a pcie->ops pointer, it doesn't need a Fixes: tag because
> there's not a problem with existing drivers and this change would not
> need to be backported.
>
> If it *is* a problem with an existing driver, please point out which
> one.

No, the existing driver does not have this problem. Only my newly added 
driver doesn't supply a pcie->ops pointer.

I will remove this Fixes tag in next revision.

Thanks,

Chen

[......]


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Re: [PATCH 3/5] PCI: sg2042: Add Sophgo SG2042 PCIe driver

[Rob Herring]

On Thu, Aug 28, 2025 at 10:17:40AM +0800, Chen Wang wrote:
> From: Chen Wang <unicorn_wang@outlook.com>
> 
> Add support for PCIe controller in SG2042 SoC. The controller
> uses the Cadence PCIe core programmed by pcie-cadence*.c. The
> PCIe controller will work in host mode only.
> 
> Signed-off-by: Chen Wang <unicorn_wang@outlook.com>
> ---
>  drivers/pci/controller/cadence/Kconfig       |  12 ++
>  drivers/pci/controller/cadence/Makefile      |   1 +
>  drivers/pci/controller/cadence/pcie-sg2042.c | 134 +++++++++++++++++++
>  3 files changed, 147 insertions(+)
>  create mode 100644 drivers/pci/controller/cadence/pcie-sg2042.c
> 
> diff --git a/drivers/pci/controller/cadence/Kconfig b/drivers/pci/controller/cadence/Kconfig
> index 666e16b6367f..b1f1941d5208 100644
> --- a/drivers/pci/controller/cadence/Kconfig
> +++ b/drivers/pci/controller/cadence/Kconfig
> @@ -42,6 +42,17 @@ config PCIE_CADENCE_PLAT_EP
>  	  endpoint mode. This PCIe controller may be embedded into many
>  	  different vendors SoCs.
>  
> +config PCIE_SG2042
> +	bool "Sophgo SG2042 PCIe controller (host mode)"
> +	depends on ARCH_SOPHGO || COMPILE_TEST
> +	depends on OF
> +	depends on PCI_MSI
> +	select PCIE_CADENCE_HOST
> +	help
> +	  Say Y here if you want to support the Sophgo SG2042 PCIe platform
> +	  controller in host mode. Sophgo SG2042 PCIe controller uses Cadence
> +	  PCIe core.
> +
>  config PCI_J721E
>  	tristate
>  	select PCIE_CADENCE_HOST if PCI_J721E_HOST != n
> @@ -67,4 +78,5 @@ config PCI_J721E_EP
>  	  Say Y here if you want to support the TI J721E PCIe platform
>  	  controller in endpoint mode. TI J721E PCIe controller uses Cadence PCIe
>  	  core.
> +
>  endmenu
> diff --git a/drivers/pci/controller/cadence/Makefile b/drivers/pci/controller/cadence/Makefile
> index 9bac5fb2f13d..4df4456d9539 100644
> --- a/drivers/pci/controller/cadence/Makefile
> +++ b/drivers/pci/controller/cadence/Makefile
> @@ -4,3 +4,4 @@ obj-$(CONFIG_PCIE_CADENCE_HOST) += pcie-cadence-host.o
>  obj-$(CONFIG_PCIE_CADENCE_EP) += pcie-cadence-ep.o
>  obj-$(CONFIG_PCIE_CADENCE_PLAT) += pcie-cadence-plat.o
>  obj-$(CONFIG_PCI_J721E) += pci-j721e.o
> +obj-$(CONFIG_PCIE_SG2042) += pcie-sg2042.o
> diff --git a/drivers/pci/controller/cadence/pcie-sg2042.c b/drivers/pci/controller/cadence/pcie-sg2042.c
> new file mode 100644
> index 000000000000..fe434dc2967e
> --- /dev/null
> +++ b/drivers/pci/controller/cadence/pcie-sg2042.c
> @@ -0,0 +1,134 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * pcie-sg2042 - PCIe controller driver for Sophgo SG2042 SoC
> + *
> + * Copyright (C) 2025 Sophgo Technology Inc.
> + * Copyright (C) 2025 Chen Wang <unicorn_wang@outlook.com>
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/of.h>

Looks like you just need mod_devicetable.h instead.

> +#include <linux/pci.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
> +
> +#include "pcie-cadence.h"
> +
> +/*
> + * SG2042 only support 4-byte aligned access, so for the rootbus (i.e. to read
> + * the Root Port itself, read32 is required. For non-rootbus (i.e. to read
> + * the PCIe peripheral registers, supports 1/2/4 byte aligned access, so
> + * directly using read should be fine.
> + *
> + * The same is true for write.
> + */
> +static int sg2042_pcie_config_read(struct pci_bus *bus, unsigned int devfn,
> +				   int where, int size, u32 *value)
> +{
> +	if (pci_is_root_bus(bus))

You can have separate pci_ops for the root bus and child buses. Do that 
and then sg2042_pcie_config_read() goes away. IIRC, there's examples in 
the tree of your exact issue (root bus being 32-bit only).

> +		return pci_generic_config_read32(bus, devfn, where, size,
> +						 value);
> +
> +	return pci_generic_config_read(bus, devfn, where, size, value);
> +}
> +
> +static int sg2042_pcie_config_write(struct pci_bus *bus, unsigned int devfn,
> +				    int where, int size, u32 value)
> +{
> +	if (pci_is_root_bus(bus))
> +		return pci_generic_config_write32(bus, devfn, where, size,
> +						  value);
> +
> +	return pci_generic_config_write(bus, devfn, where, size, value);
> +}
> +
> +static struct pci_ops sg2042_pcie_host_ops = {
> +	.map_bus	= cdns_pci_map_bus,
> +	.read		= sg2042_pcie_config_read,
> +	.write		= sg2042_pcie_config_write,
> +};
> +
> +static int sg2042_pcie_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct pci_host_bridge *bridge;
> +	struct cdns_pcie *pcie;
> +	struct cdns_pcie_rc *rc;
> +	int ret;
> +
> +	pcie = devm_kzalloc(dev, sizeof(*pcie), GFP_KERNEL);
> +	if (!pcie)
> +		return -ENOMEM;
> +
> +	bridge = devm_pci_alloc_host_bridge(dev, sizeof(*rc));
> +	if (!bridge) {
> +		dev_err(dev, "Failed to alloc host bridge!\n");
> +		return -ENOMEM;
> +	}
> +
> +	bridge->ops = &sg2042_pcie_host_ops;
> +
> +	rc = pci_host_bridge_priv(bridge);
> +	pcie = &rc->pcie;
> +	pcie->dev = dev;
> +
> +	platform_set_drvdata(pdev, pcie);
> +
> +	pm_runtime_enable(dev);
> +
> +	ret = pm_runtime_get_sync(dev);
> +	if (ret < 0) {
> +		dev_err(dev, "pm_runtime_get_sync failed\n");
> +		goto err_get_sync;
> +	}
> +
> +	ret = cdns_pcie_init_phy(dev, pcie);
> +	if (ret) {
> +		dev_err(dev, "Failed to init phy!\n");
> +		goto err_get_sync;
> +	}
> +
> +	ret = cdns_pcie_host_setup(rc);
> +	if (ret < 0) {
> +		dev_err(dev, "Failed to setup host!\n");
> +		goto err_host_setup;
> +	}
> +
> +	return 0;
> +
> +err_host_setup:
> +	cdns_pcie_disable_phy(pcie);
> +
> +err_get_sync:
> +	pm_runtime_put(dev);
> +	pm_runtime_disable(dev);
> +
> +	return ret;
> +}
> +
> +static void sg2042_pcie_shutdown(struct platform_device *pdev)
> +{
> +	struct cdns_pcie *pcie = platform_get_drvdata(pdev);
> +	struct device *dev = &pdev->dev;
> +
> +	cdns_pcie_disable_phy(pcie);
> +
> +	pm_runtime_put(dev);
> +	pm_runtime_disable(dev);
> +}
> +
> +static const struct of_device_id sg2042_pcie_of_match[] = {
> +	{ .compatible = "sophgo,sg2042-pcie-host" },
> +	{},
> +};
> +
> +static struct platform_driver sg2042_pcie_driver = {
> +	.driver = {
> +		.name		= "sg2042-pcie",
> +		.of_match_table	= sg2042_pcie_of_match,
> +		.pm		= &cdns_pcie_pm_ops,
> +	},
> +	.probe		= sg2042_pcie_probe,
> +	.shutdown	= sg2042_pcie_shutdown,
> +};
> +builtin_platform_driver(sg2042_pcie_driver);

What prevents this from being a module?

Rob

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Re: [PATCH 1/5] dt-bindings: pci: Add Sophgo SG2042 PCIe host

[Rob Herring (Arm)]

On Thu, 28 Aug 2025 10:16:54 +0800, Chen Wang wrote:
> From: Chen Wang <unicorn_wang@outlook.com>
> 
> Add binding for Sophgo SG2042 PCIe host controller.
> 
> Signed-off-by: Chen Wang <unicorn_wang@outlook.com>
> ---
>  .../bindings/pci/sophgo,sg2042-pcie-host.yaml | 66 +++++++++++++++++++
>  1 file changed, 66 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/pci/sophgo,sg2042-pcie-host.yaml
> 

Reviewed-by: Rob Herring (Arm) <robh@kernel.org>


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Re: [PATCH 3/5] PCI: sg2042: Add Sophgo SG2042 PCIe driver

[Chen Wang]

On 8/30/2025 1:09 AM, Rob Herring wrote:
> On Thu, Aug 28, 2025 at 10:17:40AM +0800, Chen Wang wrote:

[......]

>> diff --git a/drivers/pci/controller/cadence/pcie-sg2042.c b/drivers/pci/controller/cadence/pcie-sg2042.c
>> new file mode 100644
>> index 000000000000..fe434dc2967e
>> --- /dev/null
>> +++ b/drivers/pci/controller/cadence/pcie-sg2042.c
>> @@ -0,0 +1,134 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * pcie-sg2042 - PCIe controller driver for Sophgo SG2042 SoC
>> + *
>> + * Copyright (C) 2025 Sophgo Technology Inc.
>> + * Copyright (C) 2025 Chen Wang <unicorn_wang@outlook.com>
>> + */
>> +
>> +#include <linux/kernel.h>
>> +#include <linux/of.h>
> Looks like you just need mod_devicetable.h instead.

Thanks, I tried and seems just mod_devicetable.h does work.

To be honest, I am more curious about how to know which header files 
should be included. Is it just based on experience, because sometimes 
including these or those header files will compile without any problems.

>> +#include <linux/pci.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/pm_runtime.h>
>> +
>> +#include "pcie-cadence.h"
>> +
>> +/*
>> + * SG2042 only support 4-byte aligned access, so for the rootbus (i.e. to read
>> + * the Root Port itself, read32 is required. For non-rootbus (i.e. to read
>> + * the PCIe peripheral registers, supports 1/2/4 byte aligned access, so
>> + * directly using read should be fine.
>> + *
>> + * The same is true for write.
>> + */
>> +static int sg2042_pcie_config_read(struct pci_bus *bus, unsigned int devfn,
>> +				   int where, int size, u32 *value)
>> +{
>> +	if (pci_is_root_bus(bus))
> You can have separate pci_ops for the root bus and child buses. Do that
> and then sg2042_pcie_config_read() goes away. IIRC, there's examples in
> the tree of your exact issue (root bus being 32-bit only).

Yes, you're right, I learned it. Thanks,

>> +		return pci_generic_config_read32(bus, devfn, where, size,
>> +						 value);
>> +
>> +	return pci_generic_config_read(bus, devfn, where, size, value);
>> +}
>> +
>> +static int sg2042_pcie_config_write(struct pci_bus *bus, unsigned int devfn,
>> +				    int where, int size, u32 value)
>> +{
>> +	if (pci_is_root_bus(bus))
>> +		return pci_generic_config_write32(bus, devfn, where, size,
>> +						  value);
>> +
>> +	return pci_generic_config_write(bus, devfn, where, size, value);
>> +}
>> +
>> +static struct pci_ops sg2042_pcie_host_ops = {
>> +	.map_bus	= cdns_pci_map_bus,
>> +	.read		= sg2042_pcie_config_read,
>> +	.write		= sg2042_pcie_config_write,
>> +};
>> +
[......]
>> +
>> +static struct platform_driver sg2042_pcie_driver = {
>> +	.driver = {
>> +		.name		= "sg2042-pcie",
>> +		.of_match_table	= sg2042_pcie_of_match,
>> +		.pm		= &cdns_pcie_pm_ops,
>> +	},
>> +	.probe		= sg2042_pcie_probe,
>> +	.shutdown	= sg2042_pcie_shutdown,
>> +};
>> +builtin_platform_driver(sg2042_pcie_driver);
> What prevents this from being a module?

Well, I'll check again.

Thanks.

Chen

> Rob
>

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Re: [PATCH 3/5] PCI: sg2042: Add Sophgo SG2042 PCIe driver

[Manivannan Sadhasivam]

On Thu, Aug 28, 2025 at 10:17:40AM GMT, Chen Wang wrote:
> From: Chen Wang <unicorn_wang@outlook.com>
> 
> Add support for PCIe controller in SG2042 SoC. The controller
> uses the Cadence PCIe core programmed by pcie-cadence*.c. The
> PCIe controller will work in host mode only.
> 

Supported data rate, lanes etc...

> Signed-off-by: Chen Wang <unicorn_wang@outlook.com>
> ---
>  drivers/pci/controller/cadence/Kconfig       |  12 ++
>  drivers/pci/controller/cadence/Makefile      |   1 +
>  drivers/pci/controller/cadence/pcie-sg2042.c | 134 +++++++++++++++++++
>  3 files changed, 147 insertions(+)
>  create mode 100644 drivers/pci/controller/cadence/pcie-sg2042.c
> 
> diff --git a/drivers/pci/controller/cadence/Kconfig b/drivers/pci/controller/cadence/Kconfig
> index 666e16b6367f..b1f1941d5208 100644
> --- a/drivers/pci/controller/cadence/Kconfig
> +++ b/drivers/pci/controller/cadence/Kconfig
> @@ -42,6 +42,17 @@ config PCIE_CADENCE_PLAT_EP
>  	  endpoint mode. This PCIe controller may be embedded into many
>  	  different vendors SoCs.
>  
> +config PCIE_SG2042

PCIE_SG2042_HOST

> +	bool "Sophgo SG2042 PCIe controller (host mode)"

Since this driver doesn't implement irqchip, you should make it tristate and as
a module.

> +	depends on ARCH_SOPHGO || COMPILE_TEST
> +	depends on OF

	depends on OF && (ARCH_SOPHGO || COMPILE_TEST)

> +	depends on PCI_MSI
> +	select PCIE_CADENCE_HOST
> +	help
> +	  Say Y here if you want to support the Sophgo SG2042 PCIe platform
> +	  controller in host mode. Sophgo SG2042 PCIe controller uses Cadence
> +	  PCIe core.
> +
>  config PCI_J721E
>  	tristate
>  	select PCIE_CADENCE_HOST if PCI_J721E_HOST != n
> @@ -67,4 +78,5 @@ config PCI_J721E_EP
>  	  Say Y here if you want to support the TI J721E PCIe platform
>  	  controller in endpoint mode. TI J721E PCIe controller uses Cadence PCIe
>  	  core.
> +
>  endmenu
> diff --git a/drivers/pci/controller/cadence/Makefile b/drivers/pci/controller/cadence/Makefile
> index 9bac5fb2f13d..4df4456d9539 100644
> --- a/drivers/pci/controller/cadence/Makefile
> +++ b/drivers/pci/controller/cadence/Makefile
> @@ -4,3 +4,4 @@ obj-$(CONFIG_PCIE_CADENCE_HOST) += pcie-cadence-host.o
>  obj-$(CONFIG_PCIE_CADENCE_EP) += pcie-cadence-ep.o
>  obj-$(CONFIG_PCIE_CADENCE_PLAT) += pcie-cadence-plat.o
>  obj-$(CONFIG_PCI_J721E) += pci-j721e.o
> +obj-$(CONFIG_PCIE_SG2042) += pcie-sg2042.o
> diff --git a/drivers/pci/controller/cadence/pcie-sg2042.c b/drivers/pci/controller/cadence/pcie-sg2042.c
> new file mode 100644
> index 000000000000..fe434dc2967e
> --- /dev/null
> +++ b/drivers/pci/controller/cadence/pcie-sg2042.c
> @@ -0,0 +1,134 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * pcie-sg2042 - PCIe controller driver for Sophgo SG2042 SoC
> + *
> + * Copyright (C) 2025 Sophgo Technology Inc.
> + * Copyright (C) 2025 Chen Wang <unicorn_wang@outlook.com>
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/of.h>
> +#include <linux/pci.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
> +
> +#include "pcie-cadence.h"
> +
> +/*
> + * SG2042 only support 4-byte aligned access, so for the rootbus (i.e. to read
> + * the Root Port itself, read32 is required. For non-rootbus (i.e. to read
> + * the PCIe peripheral registers, supports 1/2/4 byte aligned access, so
> + * directly using read should be fine.
> + *
> + * The same is true for write.
> + */
> +static int sg2042_pcie_config_read(struct pci_bus *bus, unsigned int devfn,
> +				   int where, int size, u32 *value)
> +{
> +	if (pci_is_root_bus(bus))
> +		return pci_generic_config_read32(bus, devfn, where, size,
> +						 value);
> +
> +	return pci_generic_config_read(bus, devfn, where, size, value);
> +}
> +
> +static int sg2042_pcie_config_write(struct pci_bus *bus, unsigned int devfn,
> +				    int where, int size, u32 value)
> +{
> +	if (pci_is_root_bus(bus))
> +		return pci_generic_config_write32(bus, devfn, where, size,
> +						  value);
> +
> +	return pci_generic_config_write(bus, devfn, where, size, value);
> +}
> +
> +static struct pci_ops sg2042_pcie_host_ops = {
> +	.map_bus	= cdns_pci_map_bus,
> +	.read		= sg2042_pcie_config_read,
> +	.write		= sg2042_pcie_config_write,
> +};
> +
> +static int sg2042_pcie_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct pci_host_bridge *bridge;
> +	struct cdns_pcie *pcie;
> +	struct cdns_pcie_rc *rc;
> +	int ret;
> +
> +	pcie = devm_kzalloc(dev, sizeof(*pcie), GFP_KERNEL);
> +	if (!pcie)
> +		return -ENOMEM;
> +
> +	bridge = devm_pci_alloc_host_bridge(dev, sizeof(*rc));
> +	if (!bridge) {
> +		dev_err(dev, "Failed to alloc host bridge!\n");

Use dev_err_probe() here and below.

> +		return -ENOMEM;
> +	}
> +
> +	bridge->ops = &sg2042_pcie_host_ops;
> +
> +	rc = pci_host_bridge_priv(bridge);
> +	pcie = &rc->pcie;

You are setting drvdata only below.

> +	pcie->dev = dev;
> +
> +	platform_set_drvdata(pdev, pcie);
> +
> +	pm_runtime_enable(dev);
> +
> +	ret = pm_runtime_get_sync(dev);
> +	if (ret < 0) {
> +		dev_err(dev, "pm_runtime_get_sync failed\n");
> +		goto err_get_sync;
> +	}
> +

Why do you need pm_runtime_get_sync()? DT binding doesn't provide a
power-domain, so you just need:

	pm_runtime_set_active()
        pm_runtime_no_callbacks()
        devm_pm_runtime_enable()

> +	ret = cdns_pcie_init_phy(dev, pcie);
> +	if (ret) {
> +		dev_err(dev, "Failed to init phy!\n");
> +		goto err_get_sync;
> +	}
> +
> +	ret = cdns_pcie_host_setup(rc);
> +	if (ret < 0) {
> +		dev_err(dev, "Failed to setup host!\n");
> +		goto err_host_setup;
> +	}
> +
> +	return 0;
> +
> +err_host_setup:
> +	cdns_pcie_disable_phy(pcie);
> +
> +err_get_sync:
> +	pm_runtime_put(dev);
> +	pm_runtime_disable(dev);
> +
> +	return ret;
> +}
> +
> +static void sg2042_pcie_shutdown(struct platform_device *pdev)
> +{
> +	struct cdns_pcie *pcie = platform_get_drvdata(pdev);
> +	struct device *dev = &pdev->dev;
> +
> +	cdns_pcie_disable_phy(pcie);
> +
> +	pm_runtime_put(dev);
> +	pm_runtime_disable(dev);

You don't need these as per my above suggestion.

> +}
> +
> +static const struct of_device_id sg2042_pcie_of_match[] = {
> +	{ .compatible = "sophgo,sg2042-pcie-host" },
> +	{},
> +};
> +
> +static struct platform_driver sg2042_pcie_driver = {
> +	.driver = {
> +		.name		= "sg2042-pcie",
> +		.of_match_table	= sg2042_pcie_of_match,
> +		.pm		= &cdns_pcie_pm_ops,
> +	},
> +	.probe		= sg2042_pcie_probe,

Why no remove()?

- Mani

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Re: [PATCH 1/5] dt-bindings: pci: Add Sophgo SG2042 PCIe host

[Manivannan Sadhasivam]

On Thu, Aug 28, 2025 at 10:16:54AM GMT, Chen Wang wrote:
> From: Chen Wang <unicorn_wang@outlook.com>
> 
> Add binding for Sophgo SG2042 PCIe host controller.
> 
> Signed-off-by: Chen Wang <unicorn_wang@outlook.com>
> ---
>  .../bindings/pci/sophgo,sg2042-pcie-host.yaml | 66 +++++++++++++++++++
>  1 file changed, 66 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/pci/sophgo,sg2042-pcie-host.yaml
> 
> diff --git a/Documentation/devicetree/bindings/pci/sophgo,sg2042-pcie-host.yaml b/Documentation/devicetree/bindings/pci/sophgo,sg2042-pcie-host.yaml
> new file mode 100644
> index 000000000000..2cca3d113d11
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/pci/sophgo,sg2042-pcie-host.yaml
> @@ -0,0 +1,66 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/pci/sophgo,sg2042-pcie-host.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Sophgo SG2042 PCIe Host (Cadence PCIe Wrapper)
> +
> +description:
> +  Sophgo SG2042 PCIe host controller is based on the Cadence PCIe core.
> +
> +maintainers:
> +  - Chen Wang <unicorn_wang@outlook.com>
> +
> +properties:
> +  compatible:
> +    const: sophgo,sg2042-pcie-host
> +
> +  reg:
> +    maxItems: 2
> +
> +  reg-names:
> +    items:
> +      - const: reg
> +      - const: cfg
> +
> +  vendor-id:
> +    const: 0x1f1c
> +
> +  device-id:
> +    const: 0x2042
> +
> +  msi-parent: true
> +
> +allOf:
> +  - $ref: cdns-pcie-host.yaml#
> +
> +required:
> +  - compatible
> +  - reg
> +  - reg-names
> +  - vendor-id
> +  - device-id

Why are these IDs 'required'? The default IDs are invalid?

- Mani

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Re: [PATCH 3/5] PCI: sg2042: Add Sophgo SG2042 PCIe driver

[Chen Wang]

On 8/31/2025 12:45 PM, Manivannan Sadhasivam wrote:
> On Thu, Aug 28, 2025 at 10:17:40AM GMT, Chen Wang wrote:
>> From: Chen Wang <unicorn_wang@outlook.com>
>>
>> Add support for PCIe controller in SG2042 SoC. The controller
>> uses the Cadence PCIe core programmed by pcie-cadence*.c. The
>> PCIe controller will work in host mode only.
>>
> Supported data rate, lanes etc...
OK, I will add these descriptions in next revision.
>> Signed-off-by: Chen Wang <unicorn_wang@outlook.com>
>> ---
>>   drivers/pci/controller/cadence/Kconfig       |  12 ++
>>   drivers/pci/controller/cadence/Makefile      |   1 +
>>   drivers/pci/controller/cadence/pcie-sg2042.c | 134 +++++++++++++++++++
>>   3 files changed, 147 insertions(+)
>>   create mode 100644 drivers/pci/controller/cadence/pcie-sg2042.c
>>
>> diff --git a/drivers/pci/controller/cadence/Kconfig b/drivers/pci/controller/cadence/Kconfig
>> index 666e16b6367f..b1f1941d5208 100644
>> --- a/drivers/pci/controller/cadence/Kconfig
>> +++ b/drivers/pci/controller/cadence/Kconfig
>> @@ -42,6 +42,17 @@ config PCIE_CADENCE_PLAT_EP
>>   	  endpoint mode. This PCIe controller may be embedded into many
>>   	  different vendors SoCs.
>>   
>> +config PCIE_SG2042
> PCIE_SG2042_HOST
ok
>
>> +	bool "Sophgo SG2042 PCIe controller (host mode)"
> Since this driver doesn't implement irqchip, you should make it tristate and as
> a module.
Yes, I will implement it as a module.
>
>> +	depends on ARCH_SOPHGO || COMPILE_TEST
>> +	depends on OF
> 	depends on OF && (ARCH_SOPHGO || COMPILE_TEST)

OK

[......]

>> +
>> +	bridge = devm_pci_alloc_host_bridge(dev, sizeof(*rc));
>> +	if (!bridge) {
>> +		dev_err(dev, "Failed to alloc host bridge!\n");
> Use dev_err_probe() here and below.
OK
>> +		return -ENOMEM;
>> +	}
>> +
>> +	bridge->ops = &sg2042_pcie_host_ops;
>> +
>> +	rc = pci_host_bridge_priv(bridge);
>> +	pcie = &rc->pcie;
> You are setting drvdata only below.

Sorry, I don't understand your question here. I guess you are confused 
about the statement `platform_set_drvdata(pdev, pcie);`. Let me explain 
why we need to do like this.

Originally, I defined a drvdata stucture:

struct sg2042_pcie {
     struct cdns_pcie    *cdns_pcie;

     // other properties
};

But after code cleanup, I find there is only "cdns_pcie" left, so I 
remove the `struct sg2042_pcie` and directy set `cdns_pcie` (in new 
version, it is renamed to pcie) as drvdata.

>> +	pcie->dev = dev;
>> +
>> +	platform_set_drvdata(pdev, pcie);
>> +
>> +	pm_runtime_enable(dev);
>> +
>> +	ret = pm_runtime_get_sync(dev);
>> +	if (ret < 0) {
>> +		dev_err(dev, "pm_runtime_get_sync failed\n");
>> +		goto err_get_sync;
>> +	}
>> +
> Why do you need pm_runtime_get_sync()? DT binding doesn't provide a
> power-domain, so you just need:
>
> 	pm_runtime_set_active()
>          pm_runtime_no_callbacks()
>          devm_pm_runtime_enable()
OK, I will improve this.
>> +	ret = cdns_pcie_init_phy(dev, pcie);
>> +	if (ret) {
>> +		dev_err(dev, "Failed to init phy!\n");
>> +		goto err_get_sync;
>> +	}
>> +
>> +	ret = cdns_pcie_host_setup(rc);
>> +	if (ret < 0) {
>> +		dev_err(dev, "Failed to setup host!\n");
>> +		goto err_host_setup;
>> +	}
>> +
>> +	return 0;
>> +
>> +err_host_setup:
>> +	cdns_pcie_disable_phy(pcie);
>> +
>> +err_get_sync:
>> +	pm_runtime_put(dev);
>> +	pm_runtime_disable(dev);
>> +
>> +	return ret;
>> +}
>> +
>> +static void sg2042_pcie_shutdown(struct platform_device *pdev)
>> +{
>> +	struct cdns_pcie *pcie = platform_get_drvdata(pdev);
>> +	struct device *dev = &pdev->dev;
>> +
>> +	cdns_pcie_disable_phy(pcie);
>> +
>> +	pm_runtime_put(dev);
>> +	pm_runtime_disable(dev);
> You don't need these as per my above suggestion.
OK.
>> +}
>> +
>> +static const struct of_device_id sg2042_pcie_of_match[] = {
>> +	{ .compatible = "sophgo,sg2042-pcie-host" },
>> +	{},
>> +};
>> +
>> +static struct platform_driver sg2042_pcie_driver = {
>> +	.driver = {
>> +		.name		= "sg2042-pcie",
>> +		.of_match_table	= sg2042_pcie_of_match,
>> +		.pm		= &cdns_pcie_pm_ops,
>> +	},
>> +	.probe		= sg2042_pcie_probe,
> Why no remove()?

OK, I will replace shutdown with remove when I implement it as a module 
in next revision.

Thanks,

Chen

>
> - Mani
>

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Re: [PATCH 1/5] dt-bindings: pci: Add Sophgo SG2042 PCIe host

[Chen Wang]

On 8/31/2025 12:47 PM, Manivannan Sadhasivam wrote:
> On Thu, Aug 28, 2025 at 10:16:54AM GMT, Chen Wang wrote:
>> From: Chen Wang <unicorn_wang@outlook.com>
>>
>> Add binding for Sophgo SG2042 PCIe host controller.
>>
>> Signed-off-by: Chen Wang <unicorn_wang@outlook.com>
>> ---
>>   .../bindings/pci/sophgo,sg2042-pcie-host.yaml | 66 +++++++++++++++++++
>>   1 file changed, 66 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/pci/sophgo,sg2042-pcie-host.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/pci/sophgo,sg2042-pcie-host.yaml b/Documentation/devicetree/bindings/pci/sophgo,sg2042-pcie-host.yaml
>> new file mode 100644
>> index 000000000000..2cca3d113d11
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/pci/sophgo,sg2042-pcie-host.yaml
>> @@ -0,0 +1,66 @@
>> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/pci/sophgo,sg2042-pcie-host.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Sophgo SG2042 PCIe Host (Cadence PCIe Wrapper)
>> +
>> +description:
>> +  Sophgo SG2042 PCIe host controller is based on the Cadence PCIe core.
>> +
>> +maintainers:
>> +  - Chen Wang <unicorn_wang@outlook.com>
>> +
>> +properties:
>> +  compatible:
>> +    const: sophgo,sg2042-pcie-host
>> +
>> +  reg:
>> +    maxItems: 2
>> +
>> +  reg-names:
>> +    items:
>> +      - const: reg
>> +      - const: cfg
>> +
>> +  vendor-id:
>> +    const: 0x1f1c
>> +
>> +  device-id:
>> +    const: 0x2042
>> +
>> +  msi-parent: true
>> +
>> +allOf:
>> +  - $ref: cdns-pcie-host.yaml#
>> +
>> +required:
>> +  - compatible
>> +  - reg
>> +  - reg-names
>> +  - vendor-id
>> +  - device-id
> Why are these IDs 'required'? The default IDs are invalid?

I find the default IDs I read from the SoC is still that for Cadence, it 
would confused when I run lspci, so I replace the IDs for Sophgo.

Anyway, it's ok for me to remove IDs as "required" in bindings but still 
set it in DTS.

Thanks,

Chen

>
> - Mani
>

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