drm/i915: Pullout the bksv read and validation

For reusability purpose, this patch implements the hdcp1.4 bksv's
read and validation as a functions.

For detecting the HDMI panel's HDCP capability this fucntions will be
used.

v2:
  Rebased.
v3:
  No Changes.
v4:
  inline tag is removed with modified error msg.
v5:
  No Changes.
v6:
  No Changes.
v7:
  Realigned the code.
Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/1540286550-20399-2-git-send-email-ramalingam.c@intel.com

drivers/gpu/drm/i915/intel_hdcp.c

@@ -16,6 +16,41 @@
 
 #define KEY_LOAD_TRIES	5
 
+static
+bool intel_hdcp_is_ksv_valid(u8 *ksv)
+{
+	int i, ones = 0;
+	/* KSV has 20 1's and 20 0's */
+	for (i = 0; i < DRM_HDCP_KSV_LEN; i++)
+		ones += hweight8(ksv[i]);
+	if (ones != 20)
+		return false;
+
+	return true;
+}
+
+static
+int intel_hdcp_read_valid_bksv(struct intel_digital_port *intel_dig_port,
+			       const struct intel_hdcp_shim *shim, u8 *bksv)
+{
+	int ret, i, tries = 2;
+
+	/* HDCP spec states that we must retry the bksv if it is invalid */
+	for (i = 0; i < tries; i++) {
+		ret = shim->read_bksv(intel_dig_port, bksv);
+		if (ret)
+			return ret;
+		if (intel_hdcp_is_ksv_valid(bksv))
+			break;
+	}
+	if (i == tries) {
+		DRM_ERROR("Bksv is invalid\n");
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
 static int intel_hdcp_poll_ksv_fifo(struct intel_digital_port *intel_dig_port,
 				    const struct intel_hdcp_shim *shim)
 {
@@ -167,18 +202,6 @@ u32 intel_hdcp_get_repeater_ctl(struct intel_digital_port *intel_dig_port)
 	return -EINVAL;
 }
 
-static
-bool intel_hdcp_is_ksv_valid(u8 *ksv)
-{
-	int i, ones = 0;
-	/* KSV has 20 1's and 20 0's */
-	for (i = 0; i < DRM_HDCP_KSV_LEN; i++)
-		ones += hweight8(ksv[i]);
-	if (ones != 20)
-		return false;
-	return true;
-}
-
 static
 int intel_hdcp_validate_v_prime(struct intel_digital_port *intel_dig_port,
 				const struct intel_hdcp_shim *shim,
@@ -527,18 +550,9 @@ static int intel_hdcp_auth(struct intel_digital_port *intel_dig_port,
 
 	memset(&bksv, 0, sizeof(bksv));
 
-	/* HDCP spec states that we must retry the bksv if it is invalid */
-	for (i = 0; i < tries; i++) {
-		ret = shim->read_bksv(intel_dig_port, bksv.shim);
-		if (ret)
+	ret = intel_hdcp_read_valid_bksv(intel_dig_port, shim, bksv.shim);
+	if (ret < 0)
 		return ret;
-		if (intel_hdcp_is_ksv_valid(bksv.shim))
-			break;
-	}
-	if (i == tries) {
-		DRM_ERROR("HDCP failed, Bksv is invalid\n");
-		return -ENODEV;
-	}
 
 	I915_WRITE(PORT_HDCP_BKSVLO(port), bksv.reg[0]);
 	I915_WRITE(PORT_HDCP_BKSVHI(port), bksv.reg[1]);