[PATCH v4 3/9] usb: misc: qcom_eud: add per-path High-Speed PHY control

[Elson Serrao <elson.serrao@oss.qualcomm.com>]

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 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.

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 for proper operation.

Signed-off-by: Elson Serrao <elson.serrao@oss.qualcomm.com>
---
 drivers/usb/misc/qcom_eud.c | 126 +++++++++++++++++++++++++++++++++++-
 1 file changed, 125 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/misc/qcom_eud.c b/drivers/usb/misc/qcom_eud.c
index 4aa49f0f58c0..a624c44d5d59 100644
--- a/drivers/usb/misc/qcom_eud.c
+++ b/drivers/usb/misc/qcom_eud.c
@@ -11,6 +11,8 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/of_graph.h>
+#include <linux/phy/phy.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
 #include <linux/sysfs.h>
@@ -39,26 +41,84 @@ static const char * const eud_port_names[] = {
 	"secondary",
 };
 
+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 phy *phy;
+	int ret;
+
+	if (chip->phy_enabled)
+		return 0;
+
+	phy = chip->paths[chip->port_idx]->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 phy *phy;
+
+	if (!chip->phy_enabled)
+		return;
+
+	phy = chip->paths[chip->port_idx]->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);
@@ -75,6 +135,8 @@ 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;
 }
 
@@ -130,6 +192,12 @@ static ssize_t port_store(struct device *dev, struct device_attribute *attr,
 	if (port < 0)
 		return port;
 
+	/* 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");
@@ -229,8 +297,54 @@ 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 device_node *controller_node;
+	struct eud_path *path;
+	u32 path_num;
+	int ret;
+
+	ret = of_property_read_u32(np, "reg", &path_num);
+	if (ret) {
+		/* Legacy DT uses 'ports' node without 'reg' property; treat as path 0 */
+		if (of_node_name_eq(np, "ports"))
+			path_num = 0;
+		else
+			return dev_err_probe(chip->dev, ret, "unexpected child node '%s'\n",
+					     np->name);
+	}
+
+	if (path_num >= EUD_MAX_PORTS)
+		return dev_err_probe(chip->dev, -EINVAL, "invalid path number: %u (max %d)\n",
+				     path_num, EUD_MAX_PORTS - 1);
+
+	path = devm_kzalloc(chip->dev, sizeof(*path), GFP_KERNEL);
+	if (!path)
+		return -ENOMEM;
+
+	path->chip = chip;
+	path->num = path_num;
+
+	controller_node = of_graph_get_remote_node(np, 0, -1);
+	if (!controller_node)
+		return dev_err_probe(chip->dev, -ENODEV,
+				     "failed to get controller node for path %u\n", path_num);
+
+	path->phy = devm_of_phy_get_by_index(chip->dev, controller_node, 0);
+	of_node_put(controller_node);
+
+	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 eud_chip *chip;
 	struct resource *res;
 	int ret;
@@ -241,6 +355,16 @@ static int eud_probe(struct platform_device *pdev)
 
 	chip->dev = &pdev->dev;
 
+	for_each_child_of_node_scoped(np, child) {
+		ret = eud_init_path(chip, child);
+		if (ret)
+			return ret;
+	}
+
+	/* Primary path is mandatory. Secondary is optional */
+	if (!chip->paths[0])
+		return dev_err_probe(chip->dev, -ENODEV, "primary path not found\n");
+
 	chip->role_sw = usb_role_switch_get(&pdev->dev);
 	if (IS_ERR(chip->role_sw))
 		return dev_err_probe(chip->dev, PTR_ERR(chip->role_sw),
-- 
2.34.1