phy: phy-can-transceiver: Add support for setting mux

On some boards, for routing CAN signals from controller to transceiver,
muxes might need to be set. Therefore, add support for setting the mux by
reading the mux-states property from the device tree node.
Signed-off-by: Aswath Govindraju <a-govindraju@ti.com>
Link: https://lore.kernel.org/r/20220408111316.21189-1-a-govindraju@ti.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/phy/Kconfig

@@ -64,6 +64,7 @@ config USB_LGM_PHY
 config PHY_CAN_TRANSCEIVER
 	tristate "CAN transceiver PHY"
 	select GENERIC_PHY
+	select MULTIPLEXER
 	help
 	  This option enables support for CAN transceivers as a PHY. This
 	  driver provides function for putting the transceivers in various

drivers/phy/phy-can-transceiver.c

@@ -10,6 +10,7 @@
 #include<linux/module.h>
 #include<linux/gpio.h>
 #include<linux/gpio/consumer.h>
+#include <linux/mux/consumer.h>
 
 struct can_transceiver_data {
 	u32 flags;
@@ -21,13 +22,22 @@ struct can_transceiver_phy {
 	struct phy *generic_phy;
 	struct gpio_desc *standby_gpio;
 	struct gpio_desc *enable_gpio;
+	struct mux_state *mux_state;
 };
 
 /* Power on function */
 static int can_transceiver_phy_power_on(struct phy *phy)
 {
 	struct can_transceiver_phy *can_transceiver_phy = phy_get_drvdata(phy);
-
+	int ret;
+
+	if (can_transceiver_phy->mux_state) {
+		ret = mux_state_select(can_transceiver_phy->mux_state);
+		if (ret) {
+			dev_err(&phy->dev, "Failed to select CAN mux: %d\n", ret);
+			return ret;
+		}
+	}
 	if (can_transceiver_phy->standby_gpio)
 		gpiod_set_value_cansleep(can_transceiver_phy->standby_gpio, 0);
 	if (can_transceiver_phy->enable_gpio)
@@ -45,6 +55,8 @@ static int can_transceiver_phy_power_off(struct phy *phy)
 		gpiod_set_value_cansleep(can_transceiver_phy->standby_gpio, 1);
 	if (can_transceiver_phy->enable_gpio)
 		gpiod_set_value_cansleep(can_transceiver_phy->enable_gpio, 0);
+	if (can_transceiver_phy->mux_state)
+		mux_state_deselect(can_transceiver_phy->mux_state);
 
 	return 0;
 }
@@ -95,6 +107,16 @@ static int can_transceiver_phy_probe(struct platform_device *pdev)
 	match = of_match_node(can_transceiver_phy_ids, pdev->dev.of_node);
 	drvdata = match->data;
 
+	if (of_property_read_bool(dev->of_node, "mux-states")) {
+		struct mux_state *mux_state;
+
+		mux_state = devm_mux_state_get(dev, NULL);
+		if (IS_ERR(mux_state))
+			return dev_err_probe(&pdev->dev, PTR_ERR(mux_state),
+					     "failed to get mux\n");
+		can_transceiver_phy->mux_state = mux_state;
+	}
+
 	phy = devm_phy_create(dev, dev->of_node,
 			      &can_transceiver_phy_ops);
 	if (IS_ERR(phy)) {