Most glue driver for PCI-based DWMAC controllers utilize similar
platform suspend/resume routines. Add a generic implementation to reduce
duplicated code.

Signed-off-by: Yao Zi <ziyao@disroot.org>
---
 drivers/net/ethernet/stmicro/stmmac/Kconfig   |  9 ++++
 drivers/net/ethernet/stmicro/stmmac/Makefile  |  1 +
 .../ethernet/stmicro/stmmac/stmmac_libpci.c   | 48 +++++++++++++++++++
 .../ethernet/stmicro/stmmac/stmmac_libpci.h   | 12 +++++
 4 files changed, 70 insertions(+)
 create mode 100644 drivers/net/ethernet/stmicro/stmmac/stmmac_libpci.c
 create mode 100644 drivers/net/ethernet/stmicro/stmmac/stmmac_libpci.h

diff --git a/drivers/net/ethernet/stmicro/stmmac/Kconfig b/drivers/net/ethernet/stmicro/stmmac/Kconfig
index 87c5bea6c2a2..598bc56edd8d 100644
--- a/drivers/net/ethernet/stmicro/stmmac/Kconfig
+++ b/drivers/net/ethernet/stmicro/stmmac/Kconfig
@@ -349,6 +349,15 @@ config DWMAC_VISCONTI
 
 endif
 
+config STMMAC_LIBPCI
+	tristate "STMMAC PCI helper library"
+	depends on PCI
+	depends on STMMAC_ETH
+	default y
+	help
+	  This selects the PCI bus helpers for the stmmac driver. If you
+	  have a controller with PCI interface, say Y or M here.
+
 config DWMAC_INTEL
 	tristate "Intel GMAC support"
 	default X86
diff --git a/drivers/net/ethernet/stmicro/stmmac/Makefile b/drivers/net/ethernet/stmicro/stmmac/Makefile
index 1681a8a28313..7bf528731034 100644
--- a/drivers/net/ethernet/stmicro/stmmac/Makefile
+++ b/drivers/net/ethernet/stmicro/stmmac/Makefile
@@ -44,6 +44,7 @@ obj-$(CONFIG_DWMAC_VISCONTI)	+= dwmac-visconti.o
 stmmac-platform-objs:= stmmac_platform.o
 dwmac-altr-socfpga-objs := dwmac-socfpga.o
 
+obj-$(CONFIG_STMMAC_LIBPCI)	+= stmmac_libpci.o
 obj-$(CONFIG_STMMAC_PCI)	+= stmmac-pci.o
 obj-$(CONFIG_DWMAC_INTEL)	+= dwmac-intel.o
 obj-$(CONFIG_DWMAC_LOONGSON)	+= dwmac-loongson.o
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_libpci.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_libpci.c
new file mode 100644
index 000000000000..5c5dd502f79a
--- /dev/null
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_libpci.c
@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * PCI bus helpers for STMMAC driver
+ * Copyright (C) 2025 Yao Zi <ziyao@disroot.org>
+ */
+
+#include <linux/device.h>
+#include <linux/pci.h>
+
+#include "stmmac_libpci.h"
+
+int stmmac_pci_plat_suspend(struct device *dev, void *bsp_priv)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+	int ret;
+
+	ret = pci_save_state(pdev);
+	if (ret)
+		return ret;
+
+	pci_disable_device(pdev);
+	pci_wake_from_d3(pdev, true);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(stmmac_pci_plat_suspend);
+
+int stmmac_pci_plat_resume(struct device *dev, void *bsp_priv)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+	int ret;
+
+	pci_restore_state(pdev);
+	pci_set_power_state(pdev, PCI_D0);
+
+	ret = pci_enable_device(pdev);
+	if (ret)
+		return ret;
+
+	pci_set_master(pdev);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(stmmac_pci_plat_resume);
+
+MODULE_DESCRIPTION("STMMAC PCI helper library");
+MODULE_AUTHOR("Yao Zi <ziyao@disroot.org>");
+MODULE_LICENSE("GPL");
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_libpci.h b/drivers/net/ethernet/stmicro/stmmac/stmmac_libpci.h
new file mode 100644
index 000000000000..71553184f982
--- /dev/null
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_libpci.h
@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2025 Yao Zi <ziyao@disroot.org>
+ */
+
+#ifndef __STMMAC_LIBPCI_H__
+#define __STMMAC_LIBPCI_H__
+
+int stmmac_pci_plat_suspend(struct device *dev, void *bsp_priv);
+int stmmac_pci_plat_resume(struct device *dev, void *bsp_priv);
+
+#endif /* __STMMAC_LIBPCI_H__ */
-- 
2.51.2