usb: typec: altmodes/displayport: Add pin assignment helper

The code to extract a peripheral's currently supported Pin Assignments
is repeated in a couple of locations. Factor it out into a separate
function.

This will also make it easier to add fixes (we only need to update 1
location instead of 2).

Fixes: c1e5c2f0cb8a ("usb: typec: altmodes/displayport: correct pin assignment for UFP receptacles")
Cc: stable@vger.kernel.org
Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Prashant Malani <pmalani@chromium.org>
Reviewed-by: Benson Leung <bleung@chromium.org>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20230111020546.3384569-1-pmalani@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/typec/altmodes/displayport.c b/drivers/usb/typec/altmodes/displayport.c
index de66a29..5bc7a58 100644 (file)
--- a/drivers/usb/typec/altmodes/displayport.c
+++ b/drivers/usb/typec/altmodes/displayport.c
@@ -419,6 +419,18 @@ static const char * const pin_assignments[] = {
        [DP_PIN_ASSIGN_F] = "F",
 };
 
+/*
+ * Helper function to extract a peripheral's currently supported
+ * Pin Assignments from its DisplayPort alternate mode state.
+ */
+static u8 get_current_pin_assignments(struct dp_altmode *dp)
+{
+       if (DP_CONF_CURRENTLY(dp->data.conf) == DP_CONF_DFP_D)
+               return DP_CAP_UFP_D_PIN_ASSIGN(dp->alt->vdo);
+       else
+               return DP_CAP_DFP_D_PIN_ASSIGN(dp->alt->vdo);
+}
+
 static ssize_t
 pin_assignment_store(struct device *dev, struct device_attribute *attr,
                     const char *buf, size_t size)
@@ -445,10 +457,7 @@ pin_assignment_store(struct device *dev, struct device_attribute *attr,
                goto out_unlock;
        }
 
-       if (DP_CONF_CURRENTLY(dp->data.conf) == DP_CONF_DFP_D)
-               assignments = DP_CAP_UFP_D_PIN_ASSIGN(dp->alt->vdo);
-       else
-               assignments = DP_CAP_DFP_D_PIN_ASSIGN(dp->alt->vdo);
+       assignments = get_current_pin_assignments(dp);
 
        if (!(DP_CONF_GET_PIN_ASSIGN(conf) & assignments)) {
                ret = -EINVAL;
@@ -485,10 +494,7 @@ static ssize_t pin_assignment_show(struct device *dev,
 
        cur = get_count_order(DP_CONF_GET_PIN_ASSIGN(dp->data.conf));
 
-       if (DP_CONF_CURRENTLY(dp->data.conf) == DP_CONF_DFP_D)
-               assignments = DP_CAP_UFP_D_PIN_ASSIGN(dp->alt->vdo);
-       else
-               assignments = DP_CAP_DFP_D_PIN_ASSIGN(dp->alt->vdo);
+       assignments = get_current_pin_assignments(dp);
 
        for (i = 0; assignments; assignments >>= 1, i++) {
                if (assignments & 1) {