[PATCH v2] usb: serial: ftdi_sio: add support for u-blox EVK-M101

[Oleksandr Suvorov <cryosay@gmail.com>]

The U-Blox EVK-M101 enumerates as 1546:0506 [1] with four FTDI interfaces:
- EVK-M101 current sensors
- EVK-M101 I2C
- EVK-M101 UART
- EVK-M101 port D

Only the third USB interface is a UART. This change lets ftdi_sio probe
the VID/PID and registers only interface #3 as a TTY, leaving the rest
available for other drivers.

[1]
usb 5-1.3: new high-speed USB device number 11 using xhci_hcd
usb 5-1.3: New USB device found, idVendor=1546, idProduct=0506, bcdDevice= 8.00
usb 5-1.3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
usb 5-1.3: Product: EVK-M101
usb 5-1.3: Manufacturer: u-blox AG

Datasheet: https://content.u-blox.com/sites/default/files/documents/EVK-M10_UserGuide_UBX-21003949.pdf

Link: https://lore.kernel.org/r/20250926060235.3442748-1-cryosay@gmail.com
Signed-off-by: Oleksandr Suvorov <cryosay@gmail.com>
---
v2:
 - Restrict probing to interface #3 only
 - Add a device model to commit message
 - Fix grammar in commit message
 - Add Link: to v1
---
 drivers/usb/serial/ftdi_sio.c     | 25 +++++++++++++++++++++++++
 drivers/usb/serial/ftdi_sio_ids.h |  1 +
 2 files changed, 26 insertions(+)

diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index 49666c33b41f..4902b496d6de 100644
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -110,6 +110,7 @@ static int   ftdi_jtag_probe(struct usb_serial *serial);
 static int   ftdi_NDI_device_setup(struct usb_serial *serial);
 static int   ftdi_stmclite_probe(struct usb_serial *serial);
 static int   ftdi_8u2232c_probe(struct usb_serial *serial);
+static int   ftdi_evkm101_probe(struct usb_serial *serial);
 static void  ftdi_USB_UIRT_setup(struct ftdi_private *priv);
 static void  ftdi_HE_TIRA1_setup(struct ftdi_private *priv);
 
@@ -137,6 +138,10 @@ static const struct ftdi_quirk ftdi_8u2232c_quirk = {
 	.probe	= ftdi_8u2232c_probe,
 };
 
+static const struct ftdi_quirk ftdi_evkm101_quirk = {
+	.probe	= ftdi_evkm101_probe,
+};
+
 /*
  * The 8U232AM has the same API as the sio except for:
  * - it can support MUCH higher baudrates; up to:
@@ -1074,6 +1079,8 @@ static const struct usb_device_id id_table_combined[] = {
 	/* U-Blox devices */
 	{ USB_DEVICE(UBLOX_VID, UBLOX_C099F9P_ZED_PID) },
 	{ USB_DEVICE(UBLOX_VID, UBLOX_C099F9P_ODIN_PID) },
+	{ USB_DEVICE(UBLOX_VID, UBLOX_EVK_M101_PID),
+		.driver_info = (kernel_ulong_t)&ftdi_evkm101_quirk },
 	/* FreeCalypso USB adapters */
 	{ USB_DEVICE(FTDI_VID, FTDI_FALCONIA_JTAG_BUF_PID),
 		.driver_info = (kernel_ulong_t)&ftdi_jtag_quirk },
@@ -2362,6 +2369,24 @@ static int ftdi_stmclite_probe(struct usb_serial *serial)
 	return 0;
 }
 
+/*
+ * 1st, 2nd and 4th ports on U-Blox EVK-M101 using an FTDI FT4232H USB-to-UART
+ * are reserved for non-UART interfaces. The only 3rd port can be used as UART.
+ */
+static int ftdi_evkm101_probe(struct usb_serial *serial)
+{
+	struct usb_interface *intf = serial->interface;
+	int ifnum = intf->cur_altsetting->desc.bInterfaceNumber;
+
+	if (ifnum != 2) {
+		dev_info(&intf->dev,
+			 "Ignoring interface reserved as non-UART\n");
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
 static void ftdi_port_remove(struct usb_serial_port *port)
 {
 	struct ftdi_private *priv = usb_get_serial_port_data(port);
diff --git a/drivers/usb/serial/ftdi_sio_ids.h b/drivers/usb/serial/ftdi_sio_ids.h
index 4cc1fae8acb9..2539b9e2f712 100644
--- a/drivers/usb/serial/ftdi_sio_ids.h
+++ b/drivers/usb/serial/ftdi_sio_ids.h
@@ -1614,6 +1614,7 @@
 #define UBLOX_VID			0x1546
 #define UBLOX_C099F9P_ZED_PID		0x0502
 #define UBLOX_C099F9P_ODIN_PID		0x0503
+#define UBLOX_EVK_M101_PID		0x0506
 
 /*
  * GMC devices
-- 
2.48.1