[PATCH] USB: serial: mxuport: update number-of-ports encoding

[PATCH] USB: serial: mxuport: update number-of-ports encoding

[Johan Hovold]

In preparation for adding support for 3, 5, 6 and 7 port devices, replace
the current one-bit-per-type encoding of the number of ports with a more
compact four bit encoding (2..16 ports or undefined).

Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/usb/serial/mxuport.c | 38 +++++++++++++++---------------------
 1 file changed, 16 insertions(+), 22 deletions(-)

diff --git a/drivers/usb/serial/mxuport.c b/drivers/usb/serial/mxuport.c
index ad5fdf55a02e..591be1fe3737 100644
--- a/drivers/usb/serial/mxuport.c
+++ b/drivers/usb/serial/mxuport.c
@@ -146,11 +146,6 @@
 #define MX_WAIT_FOR_LOW_WATER		0x0040
 #define MX_WAIT_FOR_SEND_NEXT		0x0080
 
-#define MX_UPORT_2_PORT			BIT(0)
-#define MX_UPORT_4_PORT			BIT(1)
-#define MX_UPORT_8_PORT			BIT(2)
-#define MX_UPORT_16_PORT		BIT(3)
-
 /* This structure holds all of the local port information */
 struct mxuport_port {
 	u8 mcr_state;		/* Last MCR state */
@@ -159,26 +154,31 @@ struct mxuport_port {
 	spinlock_t spinlock;	/* Protects msr_state */
 };
 
+/* Encode number of ports (2..16 or undefined) */
+#define MX_PORTS_MASK			GENMASK(3, 0)
+#define MX_PORTS_OFFSET			1
+#define MX_PORTS(n)			(((n) - MX_PORTS_OFFSET) & MX_PORTS_MASK)
+
 /* Table of devices that work with this driver */
 static const struct usb_device_id mxuport_idtable[] = {
 	{ USB_DEVICE(MX_USBSERIAL_VID, MX_UPORT1250_PID),
-	  .driver_info = MX_UPORT_2_PORT },
+	  .driver_info = MX_PORTS(2) },
 	{ USB_DEVICE(MX_USBSERIAL_VID, MX_UPORT1251_PID),
-	  .driver_info = MX_UPORT_2_PORT },
+	  .driver_info = MX_PORTS(2) },
 	{ USB_DEVICE(MX_USBSERIAL_VID, MX_UPORT1410_PID),
-	  .driver_info = MX_UPORT_4_PORT },
+	  .driver_info = MX_PORTS(4) },
 	{ USB_DEVICE(MX_USBSERIAL_VID, MX_UPORT1450_PID),
-	  .driver_info = MX_UPORT_4_PORT },
+	  .driver_info = MX_PORTS(4) },
 	{ USB_DEVICE(MX_USBSERIAL_VID, MX_UPORT1451_PID),
-	  .driver_info = MX_UPORT_4_PORT },
+	  .driver_info = MX_PORTS(4) },
 	{ USB_DEVICE(MX_USBSERIAL_VID, MX_UPORT1618_PID),
-	  .driver_info = MX_UPORT_8_PORT },
+	  .driver_info = MX_PORTS(8) },
 	{ USB_DEVICE(MX_USBSERIAL_VID, MX_UPORT1658_PID),
-	  .driver_info = MX_UPORT_8_PORT },
+	  .driver_info = MX_PORTS(8) },
 	{ USB_DEVICE(MX_USBSERIAL_VID, MX_UPORT1613_PID),
-	  .driver_info = MX_UPORT_16_PORT },
+	  .driver_info = MX_PORTS(16) },
 	{ USB_DEVICE(MX_USBSERIAL_VID, MX_UPORT1653_PID),
-	  .driver_info = MX_UPORT_16_PORT },
+	  .driver_info = MX_PORTS(16) },
 	{}			/* Terminating entry */
 };
 
@@ -942,14 +942,8 @@ static int mxuport_calc_num_ports(struct usb_serial *serial,
 	int num_ports;
 	int i;
 
-	if (features & MX_UPORT_2_PORT) {
-		num_ports = 2;
-	} else if (features & MX_UPORT_4_PORT) {
-		num_ports = 4;
-	} else if (features & MX_UPORT_8_PORT) {
-		num_ports = 8;
-	} else if (features & MX_UPORT_16_PORT) {
-		num_ports = 16;
+	if (features & MX_PORTS_MASK) {
+		num_ports = (features & MX_PORTS_MASK) + MX_PORTS_OFFSET;
 	} else {
 		dev_warn(&serial->interface->dev,
 				"unknown device, assuming two ports\n");
-- 
2.53.0

Re: [PATCH] USB: serial: mxuport: update number-of-ports encoding

[Greg KH]

On Thu, May 07, 2026 at 04:11:14PM +0200, Johan Hovold wrote:
> In preparation for adding support for 3, 5, 6 and 7 port devices, replace
> the current one-bit-per-type encoding of the number of ports with a more
> compact four bit encoding (2..16 ports or undefined).
> 
> Signed-off-by: Johan Hovold <johan@kernel.org>
> ---
>  drivers/usb/serial/mxuport.c | 38 +++++++++++++++---------------------
>  1 file changed, 16 insertions(+), 22 deletions(-)

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Re: [PATCH] USB: serial: mxuport: update number-of-ports encoding

[Johan Hovold]

On Fri, May 08, 2026 at 07:16:46AM +0200, Greg Kroah-Hartman wrote:
> On Thu, May 07, 2026 at 04:11:14PM +0200, Johan Hovold wrote:
> > In preparation for adding support for 3, 5, 6 and 7 port devices, replace
> > the current one-bit-per-type encoding of the number of ports with a more
> > compact four bit encoding (2..16 ports or undefined).
> > 
> > Signed-off-by: Johan Hovold <johan@kernel.org>
> > ---
> >  drivers/usb/serial/mxuport.c | 38 +++++++++++++++---------------------
> >  1 file changed, 16 insertions(+), 22 deletions(-)
> 
> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Thanks for reviewing. Now applied.

Johan