usb: typec: fusb302: Resolve fixed power role contract setup

When the controller is configured for a fixed power role (Source
only or Sink only), attach does not proceed within the TCPM state
machine as there is no CC event generated by this driver to update
the CC line status.

To rectify this, when CC is configured as Source or Sink we now
make use of the hardware's automatic fixed Source or Sink
toggling mechanism, which detects attaches in the same way as for
DRP toggling. In this way the result of toggling is handled in the
same way by the 'fusb302_handle_togdone()' function, and CC events
are generated as expected for TCPM allowing a contract to be
established.

Signed-off-by: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/typec/tcpm/fusb302.c

@@ -679,6 +679,7 @@ static int tcpm_set_cc(struct tcpc_dev *dev, enum typec_cc_status cc)
 	int ret = 0;
 	bool pull_up, pull_down;
 	u8 rd_mda;
+	enum toggling_mode mode;
 
 	mutex_lock(&chip->lock);
 	switch (cc) {
@@ -764,6 +765,29 @@ static int tcpm_set_cc(struct tcpc_dev *dev, enum typec_cc_status cc)
 		chip->intr_comp_chng = false;
 	}
 	fusb302_log(chip, "cc := %s", typec_cc_status_name[cc]);
+
+	/* Enable detection for fixed SNK or SRC only roles */
+	switch (cc) {
+	case TYPEC_CC_RD:
+		mode = TOGGLING_MODE_SNK;
+		break;
+	case TYPEC_CC_RP_DEF:
+	case TYPEC_CC_RP_1_5:
+	case TYPEC_CC_RP_3_0:
+		mode = TOGGLING_MODE_SRC;
+		break;
+	default:
+		mode = TOGGLING_MODE_OFF;
+		break;
+	}
+
+	if (mode != TOGGLING_MODE_OFF) {
+		ret = fusb302_set_toggling(chip, mode);
+		if (ret < 0)
+			fusb302_log(chip,
+				    "cannot set fixed role toggling mode, ret=%d",
+				    ret);
+	}
 done:
 	mutex_unlock(&chip->lock);