[PATCH v4 2/3] misc: tc9564: introduce base PCI driver

[Alex Elder <elder@riscstar.com>]

The Toshiba TC9564 is small and highly-specialized SoC that implements
a PCIe switch as well as an Ethernet AVB/TSN bridge.  In addition to
these, the SoC implements other functions, including a reset and clock
controller, an address translation unit, and a few other devices.  PCIe
BARs provide access to registers that manage these IP blocks, and the
SoC is modeled using a PCI endpoint bus in devicetree.  This allows the
IP blocks to be bound to platform drivers that do MMIO via the PCI BARs.

Create a new PCI driver under drivers/misc that binds with the embedded
PCI endpoint functions within the TC9564 SoC.  Because these functions
will use devicetree pci-ep-bus to provide access to other IP blocks
within the TC9564 chip, the main purpose of this driver is to do basic
PCI initialization, then call of_platform_default_populate() to scan for
the any endpoint bus children, and probe all devices defined therein.

Because we're using pci-ep-bus, we need to use the PCI quirks mechanism
to have of_pci_make_dev_node() be called for each endpoint device in
pci_bus_add_device() (via pci_fixup_device(pci_fixup_final, dev)).

Co-developed-by: Daniel Thompson <daniel@riscstar.com>
Signed-off-by: Daniel Thompson <daniel@riscstar.com>
Signed-off-by: Alex Elder <elder@riscstar.com>
---
v4: - Refined the definition of the TC9564_PCI Kconfig entry
    - Now use pci_enable_device() rather than pcim_enable_device()

 MAINTAINERS               |  1 +
 drivers/misc/Kconfig      | 15 +++++++
 drivers/misc/Makefile     |  1 +
 drivers/misc/tc9564-pci.c | 84 +++++++++++++++++++++++++++++++++++++++
 drivers/pci/quirks.c      |  1 +
 5 files changed, 102 insertions(+)
 create mode 100644 drivers/misc/tc9564-pci.c

diff --git a/MAINTAINERS b/MAINTAINERS
index aa6b805e1ab2b..cf846853fdc79 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -27675,6 +27675,7 @@ M:	Alex Elder <elder@kernel.org>
 M:	Daniel Thompson <danielt@kernel.org>
 S:	Maintained
 F:	Documentation/devicetree/bindings/misc/pci1179,0220.yaml
+F:	drivers/misc/tc9564-pci.c
 
 TOSHIBA WMI HOTKEYS DRIVER
 M:	Azael Avalos <coproscefalo@gmail.com>
diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 7364931dad3a1..9c5b1e9d672e8 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -568,6 +568,21 @@ config MCHP_LAN966X_PCI
 	    - lan966x-miim (MDIO_MSCC_MIIM)
 	    - lan966x-switch (LAN966X_SWITCH)
 
+config TC9564_PCI
+	tristate "Toshiba TC9564 PCI function support"
+	depends on OF
+	depends on PCI
+	select PCI_DYNAMIC_OF_NODES
+	select PCI_QUIRKS
+	default m
+	help
+	  This enables support for two PCI functions implemented by the
+	  embedded PCIe endpoint in the Toshiba TC9564 SoC.  A platform
+	  driver uses a pci-ep-bus node in devicetree to provide MMIO
+	  access to other SoC devices through PCI function BARs.  A PCI
+	  quirk causes the ranges property in the endpoint's devicetree
+	  node to be updated dynamically.
+
 source "drivers/misc/c2port/Kconfig"
 source "drivers/misc/eeprom/Kconfig"
 source "drivers/misc/cb710/Kconfig"
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index e8d8d5d88c0df..7cc3d615d37a4 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -71,3 +71,4 @@ obj-y				+= keba/
 obj-y				+= amd-sbi/
 obj-$(CONFIG_MISC_RP1)		+= rp1/
 obj-$(CONFIG_INTEL_SSEI)	+= issei/
+obj-$(CONFIG_TC9564_PCI)	+= tc9564-pci.o
diff --git a/drivers/misc/tc9564-pci.c b/drivers/misc/tc9564-pci.c
new file mode 100644
index 0000000000000..e4d00dfecfca9
--- /dev/null
+++ b/drivers/misc/tc9564-pci.c
@@ -0,0 +1,84 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Copyright (C) 2026 by RISCstar Solutions Corporation.  All rights reserved.
+ */
+
+/*
+ * The Toshiba TC9564 implements a PCIe Gen 3 switch that connects an
+ * upstream x4 port to three downstream PCIe ports.  Two of the downstream
+ * ports are external, and the third is internal, implementing a PCIe
+ * endpoint which implements two PCIe functions.  Each PCIe function drives
+ * a Synopsys XGMAC Ethernet interface capable of 10 Gbps operation.
+ *
+ * The TC9564 implements other functionality, including an embedded MCU,
+ * a UART, a GPIO controller, a reset controller, a clock controller, and
+ * interrupt handling.  These features are separate from (and in some
+ * cases used by) both Ethernet XGMACs.  Each Ethernet MAC must be
+ * attached to a working PHY for it to be functional, and for this
+ * reason either of them (or both!) might not be usable/used.
+ *
+ * This PCI driver binds to the Toshiba TC9564 (physical) PCI function
+ * (VID 0x1179, DID 0x0220).
+ */
+
+#include <linux/device.h>
+#include <linux/irqdomain.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/pci.h>
+
+static void tc9564_function_remove(struct pci_dev *pdev)
+{
+	of_platform_depopulate(&pdev->dev);
+	pci_clear_master(pdev);
+	pci_disable_device(pdev);
+}
+
+static int
+tc9564_function_probe(struct pci_dev *pdev, const struct pci_device_id *id)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *np;
+	int ret;
+
+	/* Despite being a PCI device, we require devicetree */
+	np = dev_of_node(dev);
+	if (!np)
+		return dev_err_probe(dev, -EINVAL, "no devicetree node\n");
+
+	ret = pci_enable_device(pdev);
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to enable device\n");
+
+	pci_set_master(pdev);
+
+	/* Scan for pci-ep-bus (simple-bus) nodes and probe their sub-devices */
+	ret = of_platform_default_populate(np, NULL, dev);
+	if (ret)
+		goto err_depopulate;
+
+	return 0;
+
+err_depopulate:
+	tc9564_function_remove(pdev);
+
+	return dev_err_probe(dev, ret, "failed to populate platform bus\n");
+}
+
+static const struct pci_device_id tc9564_function_id_table[] = {
+	{ PCI_DEVICE(PCI_VENDOR_ID_TOSHIBA, 0x0220), },
+	{ },
+};
+MODULE_DEVICE_TABLE(pci, tc9564_function_id_table);
+
+static struct pci_driver tc9564_function_driver = {
+	.name		= KBUILD_MODNAME,
+	.id_table	= tc9564_function_id_table,
+	.probe		= tc9564_function_probe,
+	.remove		= tc9564_function_remove,
+};
+module_pci_driver(tc9564_function_driver);
+
+MODULE_DESCRIPTION("Toshiba TC9564 PCIe Embedded Function Driver");
+MODULE_LICENSE("GPL");
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index de9bbccda21fd..54e310c4153df 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -6391,6 +6391,7 @@ DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_XILINX, 0x5020, of_pci_make_dev_node);
 DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_XILINX, 0x5021, of_pci_make_dev_node);
 DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_REDHAT, 0x0005, of_pci_make_dev_node);
 DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_EFAR, 0x9660, of_pci_make_dev_node);
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_TOSHIBA, 0x0220, of_pci_make_dev_node);
 
 /*
  * Devices known to require a longer delay before first config space access
-- 
2.53.0