[PATCH v1 2/2] usb: phy: tegra: Disable internal USB sensing if extcon is used

[Svyatoslav Ryhel]

From: Jordan Viknar <jordanviknar@xxxxxxxxx>

The Tegra USB PHY features four VBUS sensors: A_VBUS_VLD, A_SESS_VLD,
B_SESS_VLD, and B_SESS_END. This allows the SoC to detect mode switches
and natively work with OTG. On some devices, instead of relying on Tegra's
own mechanism, some type of extcon detection chip may be used, which
conflicts with the native Tegra implementation.

Add extcon parsing from the linked USB controller. If such a property
exists, switch VBUS sensors to software mode and set their values to SET.
This indicates that the VBUS sensors are not required by the USB
controller, which uses extcon for detection instead.

This fixes all devices that have OTG mode set with extcon for Tegra20
(LG Optimus 2X P990), Tegra30 (LG Optimus 4X P880 and Vu P895),
Tegra114 (Nvidia Tegra Note 7), and Tegra124 (Xiaomi Mi Pad). All listed
devices were tested.

Assisted-by: Claude Sonnet 5
Signed-off-by: Jordan Viknar <jordanviknar@xxxxxxxxx>
Signed-off-by: Svyatoslav Ryhel <clamor95@xxxxxxxxx>
---
 drivers/usb/phy/phy-tegra-usb.c   | 55 +++++++++++++++++++++++++++++++
 include/linux/usb/tegra_usb_phy.h |  1 +
 2 files changed, 56 insertions(+)

diff --git a/drivers/usb/phy/phy-tegra-usb.c b/drivers/usb/phy/phy-tegra-usb.c
index 00443a7beaeb0..d3faeb6619454 100644
--- a/drivers/usb/phy/phy-tegra-usb.c
+++ b/drivers/usb/phy/phy-tegra-usb.c
@@ -16,6 +16,7 @@
 #include <linux/iopoll.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/of_address.h>
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
 #include <linux/resource.h>
@@ -68,9 +69,18 @@
 #define   UHSIC_PHY_ENABLE			BIT(19)
 
 #define USB_PHY_VBUS_SENSORS			0x404
+#define   B_SESS_VLD_SW_EN			BIT(11)
+#define   B_SESS_VLD_SW_VALUE			BIT(12)
 #define   B_SESS_VLD_WAKEUP_EN			BIT(14)
+#define   A_SESS_VLD_SW_EN			BIT(19)
+#define   A_SESS_VLD_SW_VALUE			BIT(20)
 #define   A_SESS_VLD_WAKEUP_EN			BIT(22)
+#define   A_VBUS_VLD_SW_EN			BIT(27)
+#define   A_VBUS_VLD_SW_VALUE			BIT(28)
 #define   A_VBUS_VLD_WAKEUP_EN			BIT(30)
+#define VBUS_SENSORS_SW_OVERRIDE		(B_SESS_VLD_SW_EN | B_SESS_VLD_SW_VALUE | \
+						 A_SESS_VLD_SW_EN | A_SESS_VLD_SW_VALUE | \
+						 A_VBUS_VLD_SW_EN | A_VBUS_VLD_SW_VALUE)
 
 #define USB_PHY_VBUS_WAKEUP_ID			0x408
 #define   ID_INT_EN				BIT(0)
@@ -621,6 +631,10 @@ static int utmi_phy_power_on(struct tegra_usb_phy *phy)
 		val = readl_relaxed(base + USB_PHY_VBUS_SENSORS);
 		val &= ~(A_VBUS_VLD_WAKEUP_EN | A_SESS_VLD_WAKEUP_EN);
 		val &= ~(B_SESS_VLD_WAKEUP_EN);
+
+		if (phy->has_extcon)
+			val |= VBUS_SENSORS_SW_OVERRIDE;
+
 		writel_relaxed(val, base + USB_PHY_VBUS_SENSORS);
 
 		val = readl_relaxed(base + UTMIP_BAT_CHRG_CFG0);
@@ -727,6 +741,12 @@ static int utmi_phy_power_off(struct tegra_usb_phy *phy)
 					   val, !(val & VBUS_WAKEUP_STS),
 					   5000, 100000);
 
+	if (phy->has_extcon) {
+		val = readl_relaxed(base + USB_PHY_VBUS_SENSORS);
+		val &= ~VBUS_SENSORS_SW_OVERRIDE;
+		writel_relaxed(val, base + USB_PHY_VBUS_SENSORS);
+	}
+
 	utmi_phy_clk_disable(phy);
 
 	/* PHY won't resume if reset is asserted */
@@ -1456,6 +1476,34 @@ static int tegra_usb_phy_parse_pmc(struct device *dev,
 	return 0;
 }
 
+static int tegra_usb_phy_parse_controller(struct device *dev,
+					  struct tegra_usb_phy *phy)
+{
+	struct device_node *usb_node;
+	char *node_path;
+	u64 addr;
+	int ret;
+
+	ret = of_property_read_reg(dev->of_node, 0, &addr, NULL);
+	if (ret) {
+		dev_err(dev, "Failed to read reg entry 0: %d\n", ret);
+		return ret;
+	}
+
+	node_path = devm_kasprintf(dev, GFP_KERNEL, "/usb@%08llx", addr);
+	if (!node_path)
+		return -ENOMEM;
+
+	usb_node = of_find_node_by_path(node_path);
+	if (!usb_node)
+		return -ENODEV;
+
+	phy->has_extcon = of_property_present(usb_node, "extcon");
+	of_node_put(usb_node);
+
+	return 0;
+}
+
 static const struct tegra_phy_soc_config tegra20_soc_config = {
 	.utmi_pll_config_in_car_module = false,
 	.has_hostpc = false,
@@ -1552,6 +1600,13 @@ static int tegra_usb_phy_probe(struct platform_device *pdev)
 		return err;
 	}
 
+	if (tegra_phy->mode == USB_DR_MODE_OTG) {
+		err = tegra_usb_phy_parse_controller(&pdev->dev, tegra_phy);
+		if (err)
+			return dev_err_probe(&pdev->dev, err,
+					     "Failed to get controller\n");
+	}
+
 	tegra_phy->phy_type = of_usb_get_phy_mode(np);
 	switch (tegra_phy->phy_type) {
 	case USBPHY_INTERFACE_MODE_UTMI:
diff --git a/include/linux/usb/tegra_usb_phy.h b/include/linux/usb/tegra_usb_phy.h
index 6343f88df5de8..4bb20e39003ab 100644
--- a/include/linux/usb/tegra_usb_phy.h
+++ b/include/linux/usb/tegra_usb_phy.h
@@ -87,6 +87,7 @@ struct tegra_usb_phy {
 	bool wakeup_enabled;
 	bool pad_wakeup;
 	bool powered_on;
+	bool has_extcon;
 };
 
 #endif /* __TEGRA_USB_PHY_H */
-- 
2.53.0