[PATCH v4] phy: phy-imx8mq-usb: add vbus regulator support

[Tim Harvey]

Add support for enabling and disabling vbus-supply regulator found
on several imx8mp boards in the usb3_phy0 and usb3_phy1 nodes.

Signed-off-by: Tim Harvey <tharvey at gateworks.com>
Reviewed-by: Adam Ford <aford173 at gmail.com>
Reviewed-by: Marek Vasut <marex at denx.de>
---
v4:
 - use regulator_set_enable_if_allowed to handle regulator reference counting
   errors
 - added Marek's rb tag

v3:
 - change pr_err to dev_err
 - add #if CONFIG_IS_ENABLED around vbus_supply in struct
 - add fail path to disable clock if regulator enable failed

v2:
 - protect ret with __maybe_unused in case CONFIG_CLK and
   CONFIG_DM_REGULATOR not defined
 - add error prints on failures
 - add Adam's rb tag
---
 drivers/phy/phy-imx8mq-usb.c | 39 ++++++++++++++++++++++++++++++++++--
 1 file changed, 37 insertions(+), 2 deletions(-)

diff --git a/drivers/phy/phy-imx8mq-usb.c b/drivers/phy/phy-imx8mq-usb.c
index 69f01de55538..6cbcb2338cfe 100644
--- a/drivers/phy/phy-imx8mq-usb.c
+++ b/drivers/phy/phy-imx8mq-usb.c
@@ -14,6 +14,8 @@
 #include <linux/delay.h>
 #include <linux/err.h>
 #include <clk.h>
+#include <dm/device_compat.h>
+#include <power/regulator.h>
 
 #define PHY_CTRL0			0x0
 #define PHY_CTRL0_REF_SSP_EN		BIT(2)
@@ -81,6 +83,9 @@ struct imx8mq_usb_phy {
 #endif
 	void __iomem *base;
 	enum imx8mpq_phy_type type;
+#if CONFIG_IS_ENABLED(DM_REGULATOR)
+	struct udevice *vbus_supply;
+#endif
 };
 
 static const struct udevice_id imx8mq_usb_phy_of_match[] = {
@@ -172,10 +177,10 @@ static int imx8mq_usb_phy_power_on(struct phy *usb_phy)
 {
 	struct udevice *dev = usb_phy->dev;
 	struct imx8mq_usb_phy *imx_phy = dev_get_priv(dev);
+	__maybe_unused int ret;
 	u32 value;
 
 #if CONFIG_IS_ENABLED(CLK)
-	int ret;
 	ret = clk_enable(&imx_phy->phy_clk);
 	if (ret) {
 		printf("Failed to enable usb phy clock\n");
@@ -183,18 +188,31 @@ static int imx8mq_usb_phy_power_on(struct phy *usb_phy)
 	}
 #endif
 
+	if (CONFIG_IS_ENABLED(DM_REGULATOR) && imx_phy->vbus_supply) {
+		ret = regulator_set_enable_if_allowed(imx_phy->vbus_supply, true);
+		if (ret && ret != -ENOSYS) {
+			dev_err(dev, "Failed to enable VBUS regulator: %d\n", ret);
+			goto err;
+		}
+	}
+
 	/* Disable rx term override */
 	value = readl(imx_phy->base + PHY_CTRL6);
 	value &= ~PHY_CTRL6_RXTERM_OVERRIDE_SEL;
 	writel(value, imx_phy->base + PHY_CTRL6);
 
 	return 0;
+
+err:
+	clk_disable(&imx_phy->phy_clk);
+	return ret;
 }
 
 static int imx8mq_usb_phy_power_off(struct phy *usb_phy)
 {
 	struct udevice *dev = usb_phy->dev;
 	struct imx8mq_usb_phy *imx_phy = dev_get_priv(dev);
+	__maybe_unused int ret;
 	u32 value;
 
 	/* Override rx term to be 0 */
@@ -206,6 +224,14 @@ static int imx8mq_usb_phy_power_off(struct phy *usb_phy)
 	clk_disable(&imx_phy->phy_clk);
 #endif
 
+	if (CONFIG_IS_ENABLED(DM_REGULATOR) && imx_phy->vbus_supply) {
+		ret = regulator_set_enable_if_allowed(imx_phy->vbus_supply, false);
+		if (ret && ret != -ENOSYS) {
+			dev_err(dev, "Failed to disable VBUS regulator: %d\n", ret);
+			return ret;
+		}
+	}
+
 	return 0;
 }
 
@@ -224,6 +250,7 @@ struct phy_ops imx8mq_usb_phy_ops = {
 int imx8mq_usb_phy_probe(struct udevice *dev)
 {
 	struct imx8mq_usb_phy *priv = dev_get_priv(dev);
+	__maybe_unused int ret;
 
 	priv->type = dev_get_driver_data(dev);
 	priv->base = dev_read_addr_ptr(dev);
@@ -232,7 +259,6 @@ int imx8mq_usb_phy_probe(struct udevice *dev)
 		return -EINVAL;
 
 #if CONFIG_IS_ENABLED(CLK)
-	int ret;
 
 	/* Assigned clock already set clock */
 	ret = clk_get_by_name(dev, "phy", &priv->phy_clk);
@@ -242,6 +268,15 @@ int imx8mq_usb_phy_probe(struct udevice *dev)
 	}
 #endif
 
+	if (CONFIG_IS_ENABLED(DM_REGULATOR)) {
+		ret = device_get_supply_regulator(dev, "vbus-supply",
+						  &priv->vbus_supply);
+		if (ret && ret != -ENOENT) {
+			dev_err(dev, "Failed to get VBUS regulator: %d\n", ret);
+			return ret;
+		}
+	}
+
 	return 0;
 }
 
-- 
2.25.1