[RFC net-next 15/15] net: cpc: add Bluetooth HCI driver

["Damien Riégel" <damien.riegel@silabs.com>]

Add support for Bluetooth HCI driver. As most of the protocol is already
handled by the remote endpoint, this driver is just doing some glue to
plug into CPC.

Signed-off-by: Damien Riégel <damien.riegel@silabs.com>
---
 drivers/net/cpc/Kconfig  |   2 +-
 drivers/net/cpc/Makefile |   2 +-
 drivers/net/cpc/ble.c    | 147 +++++++++++++++++++++++++++++++++++++++
 drivers/net/cpc/ble.h    |  14 ++++
 drivers/net/cpc/main.c   |  23 ++++--
 5 files changed, 181 insertions(+), 7 deletions(-)
 create mode 100644 drivers/net/cpc/ble.c
 create mode 100644 drivers/net/cpc/ble.h

diff --git a/drivers/net/cpc/Kconfig b/drivers/net/cpc/Kconfig
index f5159390a82..e8faa351bf7 100644
--- a/drivers/net/cpc/Kconfig
+++ b/drivers/net/cpc/Kconfig
@@ -2,7 +2,7 @@
 
 menuconfig CPC
 	tristate "Silicon Labs Co-Processor Communication (CPC) Protocol"
-	depends on NET && SPI
+	depends on NET && SPI && BT
 	select CRC_ITU_T
 	help
 	  Provide support for the CPC protocol to Silicon Labs EFR32 devices.
diff --git a/drivers/net/cpc/Makefile b/drivers/net/cpc/Makefile
index 195cdf4ad62..cee40aec412 100644
--- a/drivers/net/cpc/Makefile
+++ b/drivers/net/cpc/Makefile
@@ -1,5 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0
 
-cpc-y := endpoint.o header.o interface.o main.o protocol.o spi.o system.o
+cpc-y := ble.o endpoint.o header.o interface.o main.o protocol.o spi.o system.o
 
 obj-$(CONFIG_CPC)	+= cpc.o
diff --git a/drivers/net/cpc/ble.c b/drivers/net/cpc/ble.c
new file mode 100644
index 00000000000..2b7aec4dbdf
--- /dev/null
+++ b/drivers/net/cpc/ble.c
@@ -0,0 +1,147 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Driver for Bluetooth HCI over CPC.
+ *
+ * Copyright (c) 2025, Silicon Laboratories, Inc.
+ */
+
+#include <linux/skbuff.h>
+#include <net/bluetooth/bluetooth.h>
+#include <net/bluetooth/hci_core.h>
+
+#include "ble.h"
+#include "cpc.h"
+
+struct cpc_ble {
+	struct cpc_endpoint *ep;
+	struct hci_dev *hdev;
+	struct sk_buff_head txq;
+};
+
+static int cpc_ble_open(struct hci_dev *hdev)
+{
+	struct cpc_ble *ble = hci_get_drvdata(hdev);
+
+	skb_queue_head_init(&ble->txq);
+
+	return cpc_endpoint_connect(ble->ep);
+}
+
+static int cpc_ble_close(struct hci_dev *hdev)
+{
+	struct cpc_ble *ble = hci_get_drvdata(hdev);
+
+	cpc_endpoint_disconnect(ble->ep);
+
+	skb_queue_purge(&ble->txq);
+
+	return 0;
+}
+
+static int cpc_ble_flush(struct hci_dev *hdev)
+{
+	struct cpc_ble *ble = hci_get_drvdata(hdev);
+
+	skb_queue_purge(&ble->txq);
+
+	return 0;
+}
+
+static int cpc_ble_send(struct hci_dev *hdev, struct sk_buff *skb)
+{
+	struct cpc_ble *ble = hci_get_drvdata(hdev);
+
+	memcpy(skb_push(skb, 1), &hci_skb_pkt_type(skb), 1);
+
+	return cpc_endpoint_write(ble->ep, skb);
+}
+
+static void cpc_ble_rx_frame(struct cpc_endpoint *ep, struct sk_buff *skb)
+{
+	struct cpc_ble *ble = cpc_endpoint_get_drvdata(ep);
+
+	hci_skb_pkt_type(skb) = *((u8 *)skb_pull_data(skb, 1));
+	hci_skb_expect(skb) = skb->len;
+
+	hci_recv_frame(ble->hdev, skb);
+}
+
+static struct cpc_endpoint_ops cpc_ble_ops = {
+	.rx = cpc_ble_rx_frame,
+};
+
+static int cpc_ble_probe(struct cpc_endpoint *ep)
+{
+	struct cpc_ble *ble;
+	int err;
+
+	ble = kzalloc(sizeof(*ble), GFP_KERNEL);
+	if (!ble) {
+		err = -ENOMEM;
+		goto alloc_ble_fail;
+	}
+
+	cpc_endpoint_set_ops(ep, &cpc_ble_ops);
+	cpc_endpoint_set_drvdata(ep, ble);
+
+	ble->ep = ep;
+	ble->hdev = hci_alloc_dev();
+	if (!ble->hdev) {
+		err = -ENOMEM;
+		goto alloc_hdev_fail;
+	}
+
+	hci_set_drvdata(ble->hdev, ble);
+	ble->hdev->open = cpc_ble_open;
+	ble->hdev->close = cpc_ble_close;
+	ble->hdev->flush = cpc_ble_flush;
+	ble->hdev->send = cpc_ble_send;
+
+	err = hci_register_dev(ble->hdev);
+	if (err)
+		goto register_hdev_fail;
+
+	return 0;
+
+register_hdev_fail:
+	hci_free_dev(ble->hdev);
+alloc_hdev_fail:
+	kfree(ble);
+alloc_ble_fail:
+	return err;
+}
+
+static void cpc_ble_remove(struct cpc_endpoint *ep)
+{
+	struct cpc_ble *ble = cpc_endpoint_get_drvdata(ep);
+
+	hci_unregister_dev(ble->hdev);
+	hci_free_dev(ble->hdev);
+	kfree(ble);
+}
+
+static struct cpc_driver ble_driver = {
+	.driver = {
+		.name = CPC_BLUETOOTH_ENDPOINT_NAME,
+	},
+	.probe = cpc_ble_probe,
+	.remove = cpc_ble_remove,
+};
+
+/**
+ * cpc_ble_drv_register - Register the ble endpoint driver.
+ *
+ * @return: 0 on success, otherwise a negative error code.
+ */
+int cpc_ble_drv_register(void)
+{
+	return cpc_driver_register(&ble_driver);
+}
+
+/**
+ * cpc_ble_drv_unregister - Unregister the ble endpoint driver.
+ */
+void cpc_ble_drv_unregister(void)
+{
+	cpc_driver_unregister(&ble_driver);
+}
diff --git a/drivers/net/cpc/ble.h b/drivers/net/cpc/ble.h
new file mode 100644
index 00000000000..ae1cac4e7e8
--- /dev/null
+++ b/drivers/net/cpc/ble.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2025, Silicon Laboratories, Inc.
+ */
+
+#ifndef __CPC_BLE_H
+#define __CPC_BLE_H
+
+#define CPC_BLUETOOTH_ENDPOINT_NAME "silabs,cpc-ble"
+
+int cpc_ble_drv_register(void);
+void cpc_ble_drv_unregister(void);
+
+#endif
diff --git a/drivers/net/cpc/main.c b/drivers/net/cpc/main.c
index b4e73145ac2..e5636207d5d 100644
--- a/drivers/net/cpc/main.c
+++ b/drivers/net/cpc/main.c
@@ -7,6 +7,7 @@
 #include <linux/module.h>
 
 #include "cpc.h"
+#include "ble.h"
 #include "header.h"
 #include "spi.h"
 #include "system.h"
@@ -125,13 +126,24 @@ static int __init cpc_init(void)
 
 	err = cpc_system_drv_register();
 	if (err)
-		bus_unregister(&cpc_bus);
+		goto unregister_bus;
+
+	err = cpc_ble_drv_register();
+	if (err)
+		goto unregister_system_driver;
 
 	err = cpc_spi_register_driver();
-	if (err) {
-		cpc_system_drv_unregister();
-		bus_unregister(&cpc_bus);
-	}
+	if (err)
+		goto unregister_ble_driver;
+
+	return 0;
+
+unregister_ble_driver:
+	cpc_ble_drv_unregister();
+unregister_system_driver:
+	cpc_system_drv_unregister();
+unregister_bus:
+	bus_unregister(&cpc_bus);
 
 	return err;
 }
@@ -140,6 +152,7 @@ module_init(cpc_init);
 static void __exit cpc_exit(void)
 {
 	cpc_spi_unregister_driver();
+	cpc_ble_drv_unregister();
 	cpc_system_drv_unregister();
 	bus_unregister(&cpc_bus);
 }
-- 
2.49.0