usb: typec: fusb302: Refactor / simplify tcpm_set_cc()

After commit ea3b4d55 ("usb: typec: fusb302: Resolve fixed power role
contract setup"), tcpm_set_cc always calls fusb302_set_toggling.

Before this refactor tcpm_set_cc does the following:

1) fusb302_set_toggling(TOGGLING_MODE_OFF),
   this sets both FUSB_REG_MASK_BC_LVL and FUSB_REG_MASK_COMP_CHNG.
2) fusb302_set_cc_pull(...).
3) "reset cc status".
4) if pull-up fusb302_set_src_current(...).
5) if pull-up or pull-down enable bc-lvl resp comp-chng irq.
6) fusb302_set_toggling(new-toggling-mode), which again
   sets both FUSB_REG_MASK_BC_LVL and FUSB_REG_MASK_COMP_CHNG disabling
   the just enabled irq. fusb302_set_toggling is skipped when the new
   toggling mode is TOGGLING_MODE_OFF because this is already done in 1,
   note in this case 5) is a no-op.

When we are toggling the bits set by fusb302_set_cc_pull will be ignored
until we turn toggling off, so we can safely move the fusb302_set_cc_pull
call to before setting TOGGLING_MODE_OFF.

Either we are not toggling yet, or the src-current has already been set,
so we can also safely set the src-current earlier, allowing us to do the
fusb302_set_toggling(TOGGLING_MODE_OFF) call at the same time as we
set the other toggling modes. Also setting the src-current is a no-op
when not enabling pull-ups, so we can drop the if.

And since the second fusb302_set_toggling undoes the effects of step 5,
we can skip step 5, the bc-lvl resp comp-chng irq wil be enabled by
fusb302_handle_togdone_snk resp. fusb302_handle_togdone_src when toggling
is done.

Together this allows us to simplify things to:

1) fusb302_set_cc_pull(...)
2) "reset cc status"
3) fusb302_set_src_current(...)
4) fusb302_set_toggling(new-toggling-mode)

This commit does this, leading to a nice cleanup.
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/typec/tcpm/fusb302.c

@@ -676,7 +676,6 @@ static int tcpm_set_cc(struct tcpc_dev *dev, enum typec_cc_status cc)
 						 tcpc_dev);
 	int ret = 0;
 	bool pull_up, pull_down;
-	u8 rd_mda;
 	enum toggling_mode mode;
 
 	mutex_lock(&chip->lock);
@@ -684,16 +683,19 @@ static int tcpm_set_cc(struct tcpc_dev *dev, enum typec_cc_status cc)
 	case TYPEC_CC_OPEN:
 		pull_up = false;
 		pull_down = false;
+		mode = TOGGLING_MODE_OFF;
 		break;
 	case TYPEC_CC_RD:
 		pull_up = false;
 		pull_down = true;
+		mode = TOGGLING_MODE_SNK;
 		break;
 	case TYPEC_CC_RP_DEF:
 	case TYPEC_CC_RP_1_5:
 	case TYPEC_CC_RP_3_0:
 		pull_up = true;
 		pull_down = false;
+		mode = TOGGLING_MODE_SRC;
 		break;
 	default:
 		fusb302_log(chip, "unsupported cc value %s",
@@ -701,11 +703,9 @@ static int tcpm_set_cc(struct tcpc_dev *dev, enum typec_cc_status cc)
 		ret = -EINVAL;
 		goto done;
 	}
-	ret = fusb302_set_toggling(chip, TOGGLING_MODE_OFF);
-	if (ret < 0) {
-		fusb302_log(chip, "cannot stop toggling, ret=%d", ret);
-		goto done;
-	}
+
+	fusb302_log(chip, "cc := %s", typec_cc_status_name[cc]);
+
 	ret = fusb302_set_cc_pull(chip, pull_up, pull_down);
 	if (ret < 0) {
 		fusb302_log(chip,
@@ -718,74 +718,19 @@ static int tcpm_set_cc(struct tcpc_dev *dev, enum typec_cc_status cc)
 	/* reset the cc status */
 	chip->cc1 = TYPEC_CC_OPEN;
 	chip->cc2 = TYPEC_CC_OPEN;
+
 	/* adjust current for SRC */
-	if (pull_up) {
-		ret = fusb302_set_src_current(chip, cc_src_current[cc]);
-		if (ret < 0) {
-			fusb302_log(chip, "cannot set src current %s, ret=%d",
-				    typec_cc_status_name[cc], ret);
-			goto done;
-		}
-	}
-	/* enable/disable interrupts, BC_LVL for SNK and COMP_CHNG for SRC */
-	if (pull_up) {
-		rd_mda = rd_mda_value[cc_src_current[cc]];
-		ret = fusb302_i2c_write(chip, FUSB_REG_MEASURE, rd_mda);
-		if (ret < 0) {
-			fusb302_log(chip,
-				    "cannot set SRC measure value, ret=%d",
-				    ret);
-			goto done;
-		}
-		ret = fusb302_i2c_mask_write(chip, FUSB_REG_MASK,
-					     FUSB_REG_MASK_BC_LVL |
-					     FUSB_REG_MASK_COMP_CHNG,
-					     FUSB_REG_MASK_COMP_CHNG);
-		if (ret < 0) {
-			fusb302_log(chip, "cannot set SRC interrupt, ret=%d",
-				    ret);
-			goto done;
-		}
-		chip->intr_bc_lvl = false;
-		chip->intr_comp_chng = true;
-	}
-	if (pull_down) {
-		ret = fusb302_i2c_mask_write(chip, FUSB_REG_MASK,
-					     FUSB_REG_MASK_BC_LVL |
-					     FUSB_REG_MASK_COMP_CHNG,
-					     FUSB_REG_MASK_BC_LVL);
-		if (ret < 0) {
-			fusb302_log(chip, "cannot set SRC interrupt, ret=%d",
-				    ret);
-			goto done;
-		}
-		chip->intr_bc_lvl = true;
-		chip->intr_comp_chng = false;
+	ret = fusb302_set_src_current(chip, cc_src_current[cc]);
+	if (ret < 0) {
+		fusb302_log(chip, "cannot set src current %s, ret=%d",
+			    typec_cc_status_name[cc], ret);
+		goto done;
 	}
-	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;
-	}
+	ret = fusb302_set_toggling(chip, mode);
+	if (ret < 0)
+		fusb302_log(chip, "cannot set toggling mode, ret=%d", ret);
 
-	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);