[PATCH 2/4] USB: serial: ftdi_sio: Report the valid GPIO lines to gpiolib

[Marc Zyngier <maz@xxxxxxxxxx>]

Since it is pretty common for only some of the CBUS lines to be
valid as GPIO lines, let's report such validity to the rest of
the kernel.

Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
---
 drivers/usb/serial/ftdi_sio.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index e0f4c3d9649c..13e575f16bcd 100644
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -2002,6 +2002,19 @@ static int ftdi_gpio_direction_output(struct gpio_chip *gc, unsigned int gpio,
 	return result;
 }
 
+static int ftdi_gpio_init_valid_mask(struct gpio_chip *gc,
+				     unsigned long *valid_mask,
+				     unsigned int ngpios)
+{
+	struct usb_serial_port *port = gpiochip_get_data(gc);
+	struct ftdi_private *priv = usb_get_serial_port_data(port);
+	unsigned long map = priv->gpio_altfunc;
+
+	bitmap_complement(valid_mask, &map, ngpios);
+
+	return 0;
+}
+
 static int ftdi_read_eeprom(struct usb_serial *serial, void *dst, u16 addr,
 				u16 nbytes)
 {
@@ -2173,6 +2186,7 @@ static int ftdi_gpio_init(struct usb_serial_port *port)
 	priv->gc.get_direction = ftdi_gpio_direction_get;
 	priv->gc.direction_input = ftdi_gpio_direction_input;
 	priv->gc.direction_output = ftdi_gpio_direction_output;
+	priv->gc.init_valid_mask = ftdi_gpio_init_valid_mask;
 	priv->gc.get = ftdi_gpio_get;
 	priv->gc.set = ftdi_gpio_set;
 	priv->gc.get_multiple = ftdi_gpio_get_multiple;
-- 
2.28.0