Hi Marc,

On 22/11/21 6:42 pm, Marc Kleine-Budde wrote:

On 22.11.2021 18:26:24, Aswath Govindraju wrote:

quoted

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-controls property from the device tree node.

Signed-off-by: Aswath Govindraju <redacted>
---
 drivers/phy/phy-can-transceiver.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/drivers/phy/phy-can-transceiver.c b/drivers/phy/phy-can-transceiver.c
index 6f3fe37dee0e..15056b9d68ba 100644
--- a/drivers/phy/phy-can-transceiver.c
+++ b/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 +22,23 @@ struct can_transceiver_phy {
 	struct phy *generic_phy;
 	struct gpio_desc *standby_gpio;
 	struct gpio_desc *enable_gpio;
+	struct mux_control *mux_ctrl;
 };
 
 /* Power on function */
 static int can_transceiver_phy_power_on(struct phy *phy)
 {
+	int ret;
 	struct can_transceiver_phy *can_transceiver_phy = phy_get_drvdata(phy);
 
+	if (can_transceiver_phy->mux_ctrl) {
+		ret = mux_control_select(can_transceiver_phy->mux_ctrl,
+					 mux_control_enable_state(can_transceiver_phy->mux_ctrl));
+		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 +56,8 @@ 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_ctrl)
+		mux_control_deselect(can_transceiver_phy->mux_ctrl);
 
 	return 0;
 }

@@ -95,6 +108,19 @@ 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-controls")) {
+		struct mux_control *control;
+		int ret;
+
+		control = devm_mux_control_get(dev, NULL);
+		if (IS_ERR(control)) {
+			ret = PTR_ERR(control);
+			dev_err_probe(&pdev->dev, ret, "failed to get mux\n");
+			return PTR_ERR(control);
+		}
+		can_transceiver_phy->mux_ctrl = control;
+	}

What about adding a devm_mux_control_get_optional(), which doesn't
return a -ENODEV but a NULL pointer if the device doesn't exist?

I tried adding it in the following manner,

+/**
+ * devm_mux_control_optional_get() - Optionally get the mux-control for a
+ *                                  device, with resource management.
+ * @dev: The device that needs a mux-control.
+ * @mux_name: The name identifying the mux-control.
+ *
+ * This differs from devm_mux_control_get in that if the mux does not
+ * exist, it is not considered an error and -ENODEV will not be
+ * returned. Instead the NULL is returned.
+ *
+ * Return: Pointer to the mux-control, or an ERR_PTR with a negative errno.
+ */
+struct mux_control *devm_mux_control_optional_get(struct device *dev,
+                                                 const char *mux_name)
+{
+       struct mux_control *mux_ctrl;
+
+       mux_ctrl = devm_mux_control_get(dev, mux_name);
+       if (PTR_ERR(mux_ctrl) == -ENOENT)
+                mux_ctrl = NULL;
+
+       return mux_ctrl;
+}
+EXPORT_SYMBOL_GPL(devm_mux_control_optional_get);
+

However the issue is that there is a print in mux_control_get()
 dev_err(dev, "%pOF: failed to get mux-control %s(%i)\n",

which is getting printed, whenever mux-controls property is not found.
Therefore, I was not sure about how to go about this issue and did not
implement it.

Thanks,
Aswath

Marc

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