EUD hardware can support multiple High-Speed USB paths, each routed
through its own PHY. The active path is selected in hardware via the
EUD_PORT_SEL register. As a High-Speed hub, EUD requires access to the
High-Speed PHY associated with the active UTMI path. To support this
multi-path capability, the driver must manage PHY resources on a per-path
basis, ensuring that the PHY for the currently selected path is properly
initialized and powered.

This patch restructures the driver to implement per-path PHY management.
The driver now powers the appropriate PHY based on the selected and
enabled UTMI path, ensuring correct operation when EUD is enabled.

Supporting this requires describing the available UTMI paths and their
corresponding PHYs in Device Tree. This updates DT requirements and is
not backward compatible with older DTs that lacked this description.
Historically, EUD appeared to work on single-path systems because the
USB controller kept the PHY initialized. However, EUD is designed to
operate independently of the USB controller and therefore requires
explicit PHY control.

Signed-off-by: Elson Serrao <elson.serrao@oss.qualcomm.com>
---
 drivers/usb/misc/qcom_eud.c | 130 +++++++++++++++++++++++++++++++++++-
 1 file changed, 129 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/misc/qcom_eud.c b/drivers/usb/misc/qcom_eud.c
index 1a136f8f1ae5..5cebb64f4a67 100644
--- a/drivers/usb/misc/qcom_eud.c
+++ b/drivers/usb/misc/qcom_eud.c
@@ -11,6 +11,7 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/phy/phy.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
 #include <linux/sysfs.h>
@@ -34,26 +35,96 @@
 #define EUD_INT_SAFE_MODE	BIT(4)
 #define EUD_INT_ALL		(EUD_INT_VBUS | EUD_INT_SAFE_MODE)
 
+struct eud_path {
+	struct eud_chip		*chip;
+	struct phy		*phy;
+	u8			num;
+};
+
 struct eud_chip {
 	struct device			*dev;
 	struct usb_role_switch		*role_sw;
 	void __iomem			*base;
+	struct eud_path			*paths[EUD_MAX_PORTS];
 	phys_addr_t			mode_mgr;
 	unsigned int			int_status;
 	int				irq;
 	bool				enabled;
 	bool				usb_attached;
+	bool				phy_enabled;
 	u8				port_idx;
 };
 
+static int eud_phy_enable(struct eud_chip *chip)
+{
+	struct eud_path *path;
+	struct phy *phy;
+	int ret;
+
+	if (chip->phy_enabled)
+		return 0;
+
+	path = chip->paths[chip->port_idx];
+	if (!path || !path->phy) {
+		dev_err(chip->dev, "No PHY configured for port %u\n", chip->port_idx);
+		return -ENODEV;
+	}
+
+	phy = path->phy;
+
+	ret = phy_init(phy);
+	if (ret) {
+		dev_err(chip->dev, "Failed to initialize USB2 PHY for port %u: %d\n",
+			chip->port_idx, ret);
+		return ret;
+	}
+
+	ret = phy_power_on(phy);
+	if (ret) {
+		dev_err(chip->dev, "Failed to power on USB2 PHY for port %u: %d\n",
+			chip->port_idx, ret);
+		phy_exit(phy);
+		return ret;
+	}
+
+	chip->phy_enabled = true;
+
+	return 0;
+}
+
+static void eud_phy_disable(struct eud_chip *chip)
+{
+	struct eud_path *path;
+	struct phy *phy;
+
+	if (!chip->phy_enabled)
+		return;
+
+	path = chip->paths[chip->port_idx];
+	if (!path || !path->phy)
+		return;
+
+	phy = path->phy;
+
+	phy_power_off(phy);
+	phy_exit(phy);
+	chip->phy_enabled = false;
+}
+
 static int enable_eud(struct eud_chip *priv)
 {
 	int ret;
 
-	ret = qcom_scm_io_writel(priv->mode_mgr + EUD_REG_EUD_EN2, 1);
+	ret = eud_phy_enable(priv);
 	if (ret)
 		return ret;
 
+	ret = qcom_scm_io_writel(priv->mode_mgr + EUD_REG_EUD_EN2, 1);
+	if (ret) {
+		eud_phy_disable(priv);
+		return ret;
+	}
+
 	writel(EUD_ENABLE, priv->base + EUD_REG_CSR_EUD_EN);
 	writel(EUD_INT_VBUS | EUD_INT_SAFE_MODE,
 			priv->base + EUD_REG_INT1_EN_MASK);
@@ -70,6 +141,8 @@ static int disable_eud(struct eud_chip *priv)
 		return ret;
 
 	writel(0, priv->base + EUD_REG_CSR_EUD_EN);
+	eud_phy_disable(priv);
+
 	return 0;
 }
 
@@ -132,6 +205,12 @@ static ssize_t port_store(struct device *dev,
 	if (port >= EUD_MAX_PORTS)
 		return -EINVAL;
 
+	/* Check if the corresponding path is available */
+	if (!chip->paths[port]) {
+		dev_err(chip->dev, "EUD not supported on selected port\n");
+		return -EOPNOTSUPP;
+	}
+
 	/* Port selection must be done before enabling EUD */
 	if (chip->enabled) {
 		dev_err(chip->dev, "Cannot change port while EUD is enabled\n");
@@ -231,8 +310,45 @@ static void eud_role_switch_release(void *data)
 	usb_role_switch_put(chip->role_sw);
 }
 
+static int eud_init_path(struct eud_chip *chip, struct device_node *np)
+{
+	struct eud_path *path;
+	u32 path_num;
+	int ret;
+
+	ret = of_property_read_u32(np, "reg", &path_num);
+	if (ret) {
+		dev_err(chip->dev, "Missing 'reg' property in path node\n");
+		return ret;
+	}
+
+	if (path_num >= EUD_MAX_PORTS) {
+		dev_err(chip->dev, "Invalid path number: %u (max %d)\n",
+			path_num, EUD_MAX_PORTS - 1);
+		return -EINVAL;
+	}
+
+	path = devm_kzalloc(chip->dev, sizeof(*path), GFP_KERNEL);
+	if (!path)
+		return -ENOMEM;
+
+	path->chip = chip;
+	path->num = path_num;
+
+	path->phy = devm_of_phy_get(chip->dev, np, NULL);
+	if (IS_ERR(path->phy))
+		return dev_err_probe(chip->dev, PTR_ERR(path->phy),
+				     "Failed to get PHY for path %d\n", path_num);
+
+	chip->paths[path_num] = path;
+
+	return 0;
+}
+
 static int eud_probe(struct platform_device *pdev)
 {
+	struct device_node *np = pdev->dev.of_node;
+	struct device_node *child;
 	struct eud_chip *chip;
 	struct resource *res;
 	int ret;
@@ -252,6 +368,18 @@ static int eud_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
+	for_each_child_of_node(np, child) {
+		ret = eud_init_path(chip, child);
+		if (ret) {
+			of_node_put(child);
+			return ret;
+		}
+	}
+
+	/* Primary path is mandatory. Secondary is optional */
+	if (!chip->paths[0])
+		return -ENODEV;
+
 	chip->base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(chip->base))
 		return PTR_ERR(chip->base);
-- 
2.34.1

On 1/27/26 12:38 AM, Elson Serrao wrote:
> EUD hardware can support multiple High-Speed USB paths, each routed
> through its own PHY. The active path is selected in hardware via the
> EUD_PORT_SEL register. As a High-Speed hub, EUD requires access to the
> High-Speed PHY associated with the active UTMI path. To support this
> multi-path capability, the driver must manage PHY resources on a per-path
> basis, ensuring that the PHY for the currently selected path is properly
> initialized and powered.
> 
> This patch restructures the driver to implement per-path PHY management.
> The driver now powers the appropriate PHY based on the selected and
> enabled UTMI path, ensuring correct operation when EUD is enabled.
> 
> Supporting this requires describing the available UTMI paths and their
> corresponding PHYs in Device Tree. This updates DT requirements and is
> not backward compatible with older DTs that lacked this description.
> Historically, EUD appeared to work on single-path systems because the
> USB controller kept the PHY initialized. However, EUD is designed to
> operate independently of the USB controller and therefore requires
> explicit PHY control.
> 
> Signed-off-by: Elson Serrao <elson.serrao@oss.qualcomm.com>
> ---

[...]

> +static int eud_phy_enable(struct eud_chip *chip)
> +{
> +	struct eud_path *path;
> +	struct phy *phy;
> +	int ret;
> +
> +	if (chip->phy_enabled)
> +		return 0;
> +
> +	path = chip->paths[chip->port_idx];
> +	if (!path || !path->phy) {

I think neither are possible - path is != NULL since we can't enter into
this function without failing the check in _store and !path->phy would error
out in probe()->eud_init_path()

[...]

> +static void eud_phy_disable(struct eud_chip *chip)
> +{
> +	struct eud_path *path;
> +	struct phy *phy;
> +
> +	if (!chip->phy_enabled)
> +		return;
> +
> +	path = chip->paths[chip->port_idx];
> +	if (!path || !path->phy)

Likewise

[...]

> +static int eud_init_path(struct eud_chip *chip, struct device_node *np)
> +{
> +	struct eud_path *path;
> +	u32 path_num;
> +	int ret;
> +
> +	ret = of_property_read_u32(np, "reg", &path_num);
> +	if (ret) {
> +		dev_err(chip->dev, "Missing 'reg' property in path node\n");
> +		return ret;

You can use return dev_err_probe like you did a little below

> +	}
> +
> +	if (path_num >= EUD_MAX_PORTS) {
> +		dev_err(chip->dev, "Invalid path number: %u (max %d)\n",
> +			path_num, EUD_MAX_PORTS - 1);
> +		return -EINVAL;
> +	}
> +
> +	path = devm_kzalloc(chip->dev, sizeof(*path), GFP_KERNEL);
> +	if (!path)
> +		return -ENOMEM;
> +
> +	path->chip = chip;
> +	path->num = path_num;
> +
> +	path->phy = devm_of_phy_get(chip->dev, np, NULL);
> +	if (IS_ERR(path->phy))
> +		return dev_err_probe(chip->dev, PTR_ERR(path->phy),
> +				     "Failed to get PHY for path %d\n", path_num);
> +
> +	chip->paths[path_num] = path;
> +
> +	return 0;
> +}
> +
>  static int eud_probe(struct platform_device *pdev)
>  {
> +	struct device_node *np = pdev->dev.of_node;
> +	struct device_node *child;
>  	struct eud_chip *chip;
>  	struct resource *res;
>  	int ret;
> @@ -252,6 +368,18 @@ static int eud_probe(struct platform_device *pdev)
>  	if (ret)
>  		return ret;
>  
> +	for_each_child_of_node(np, child) {

With for_each_child_of_node_scoped(), you can dispose of the manual
_put()

> +		ret = eud_init_path(chip, child);
> +		if (ret) {
> +			of_node_put(child);
> +			return ret;
> +		}
> +	}
> +
> +	/* Primary path is mandatory. Secondary is optional */
> +	if (!chip->paths[0])
> +		return -ENODEV;

I'm going to assume we don't have any funny chips that violate this :)

Konrad