reset: renesas: Add USB VBUS regulator device as child

As per RZ/G2L HW manual, VBUS enable can be controlled by the VBOUT bit
of the VBUS Control Register(VBENCTL) register in the USBPHY Control.

Expose this register as regmap and instantiate the USB VBUS regulator
device, so that consumer can control the vbus using regulator API's
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Link: https://lore.kernel.org/r/20240702180032.207275-3-biju.das.jz@bp.renesas.comSigned-off-by: Philipp Zabel <p.zabel@pengutronix.de>

drivers/reset/reset-rzg2l-usbphy-ctrl.c

@@ -10,10 +10,12 @@
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
+#include <linux/regmap.h>
 #include <linux/reset.h>
 #include <linux/reset-controller.h>
 
 #define RESET			0x000
+#define VBENCTL			0x03c
 
 #define RESET_SEL_PLLRESET	BIT(12)
 #define RESET_PLLRESET		BIT(8)
@@ -32,6 +34,7 @@ struct rzg2l_usbphy_ctrl_priv {
 	struct reset_controller_dev rcdev;
 	struct reset_control *rstc;
 	void __iomem *base;
+	struct platform_device *vdev;
 
 	spinlock_t lock;
 };
@@ -100,10 +103,19 @@ static const struct reset_control_ops rzg2l_usbphy_ctrl_reset_ops = {
 	.status = rzg2l_usbphy_ctrl_status,
 };
 
+static const struct regmap_config rzg2l_usb_regconf = {
+	.reg_bits = 32,
+	.val_bits = 32,
+	.reg_stride = 4,
+	.max_register = 1,
+};
+
 static int rzg2l_usbphy_ctrl_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct rzg2l_usbphy_ctrl_priv *priv;
+	struct platform_device *vdev;
+	struct regmap *regmap;
 	unsigned long flags;
 	int error;
 	u32 val;
@@ -116,6 +128,10 @@ static int rzg2l_usbphy_ctrl_probe(struct platform_device *pdev)
 	if (IS_ERR(priv->base))
 		return PTR_ERR(priv->base);
 
+	regmap = devm_regmap_init_mmio(dev, priv->base + VBENCTL, &rzg2l_usb_regconf);
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
 	priv->rstc = devm_reset_control_get_exclusive(&pdev->dev, NULL);
 	if (IS_ERR(priv->rstc))
 		return dev_err_probe(dev, PTR_ERR(priv->rstc),
@@ -152,8 +168,22 @@ static int rzg2l_usbphy_ctrl_probe(struct platform_device *pdev)
 	if (error)
 		goto err_pm_runtime_put;
 
+	vdev = platform_device_alloc("rzg2l-usb-vbus-regulator", pdev->id);
+	if (!vdev) {
+		error = -ENOMEM;
+		goto err_pm_runtime_put;
+	}
+	vdev->dev.parent = dev;
+	priv->vdev = vdev;
+
+	error = platform_device_add(vdev);
+	if (error)
+		goto err_device_put;
+
 	return 0;
 
+err_device_put:
+	platform_device_put(vdev);
 err_pm_runtime_put:
 	pm_runtime_put(&pdev->dev);
 err_pm_disable_reset_deassert:
@@ -166,6 +196,7 @@ static int rzg2l_usbphy_ctrl_remove(struct platform_device *pdev)
 {
 	struct rzg2l_usbphy_ctrl_priv *priv = dev_get_drvdata(&pdev->dev);
 
+	platform_device_unregister(priv->vdev);
 	pm_runtime_put(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);
 	reset_control_assert(priv->rstc);