phy: Add a driver for the ATH79 USB phy

The ATH79 USB phy is very simple, it only have a reset. On some SoC a
second reset is used to force the phy in suspend mode regardless of the
USB controller status.

This driver is added to the qualcom directory as atheros is now part
of qualcom and newer SoC of this familly are marketed under the
qualcom name.

Signed-off-by: Alban Bedel <albeu@free.fr>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>

MAINTAINERS

@@ -2326,6 +2326,14 @@ S:	Maintained
 F:	drivers/gpio/gpio-ath79.c
 F:	Documentation/devicetree/bindings/gpio/gpio-ath79.txt
 
+ATHEROS 71XX/9XXX USB PHY DRIVER
+M:	Alban Bedel <albeu@free.fr>
+W:	https://github.com/AlbanBedel/linux
+T:	git git://github.com/AlbanBedel/linux
+S:	Maintained
+F:	drivers/phy/qualcomm/phy-ath79-usb.c
+F:	Documentation/devicetree/bindings/phy/phy-ath79-usb.txt
+
 ATHEROS ATH GENERIC UTILITIES
 M:	"Luis R. Rodriguez" <mcgrof@do-not-panic.com>
 L:	linux-wireless@vger.kernel.org

drivers/phy/qualcomm/Kconfig

@@ -1,6 +1,15 @@
 #
-# Phy drivers for Qualcomm platforms
+# Phy drivers for Qualcomm and Atheros platforms
 #
+config PHY_ATH79_USB
+	tristate "Atheros AR71XX/9XXX USB PHY driver"
+	depends on OF && (ATH79 || COMPILE_TEST)
+	default y if USB_EHCI_HCD_PLATFORM || USB_OHCI_HCD_PLATFORM
+	select RESET_CONTROLLER
+	select GENERIC_PHY
+	help
+	  Enable this to support the USB PHY on Atheros AR71XX/9XXX SoCs.
+
 config PHY_QCOM_APQ8064_SATA
 	tristate "Qualcomm APQ8064 SATA SerDes/PHY driver"
 	depends on ARCH_QCOM

drivers/phy/qualcomm/Makefile

@@ -1,4 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0
+obj-$(CONFIG_PHY_ATH79_USB)		+= phy-ath79-usb.o
 obj-$(CONFIG_PHY_QCOM_APQ8064_SATA)	+= phy-qcom-apq8064-sata.o
 obj-$(CONFIG_PHY_QCOM_IPQ806X_SATA)	+= phy-qcom-ipq806x-sata.o
 obj-$(CONFIG_PHY_QCOM_QMP)		+= phy-qcom-qmp.o

drivers/phy/qualcomm/phy-ath79-usb.c

@@ -0,0 +1,108 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Atheros AR71XX/9XXX USB PHY driver
+ *
+ * Copyright (C) 2015-2018 Alban Bedel <albeu@free.fr>
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/phy/phy.h>
+#include <linux/reset.h>
+
+struct ath79_usb_phy {
+	struct reset_control *reset;
+	/* The suspend override logic is inverted, hence the no prefix
+	 * to make the code a bit easier to understand.
+	 */
+	struct reset_control *no_suspend_override;
+};
+
+static int ath79_usb_phy_power_on(struct phy *phy)
+{
+	struct ath79_usb_phy *priv = phy_get_drvdata(phy);
+	int err = 0;
+
+	if (priv->no_suspend_override) {
+		err = reset_control_assert(priv->no_suspend_override);
+		if (err)
+			return err;
+	}
+
+	err = reset_control_deassert(priv->reset);
+	if (err && priv->no_suspend_override)
+		reset_control_assert(priv->no_suspend_override);
+
+	return err;
+}
+
+static int ath79_usb_phy_power_off(struct phy *phy)
+{
+	struct ath79_usb_phy *priv = phy_get_drvdata(phy);
+	int err = 0;
+
+	err = reset_control_assert(priv->reset);
+	if (err)
+		return err;
+
+	if (priv->no_suspend_override) {
+		err = reset_control_deassert(priv->no_suspend_override);
+		if (err)
+			reset_control_deassert(priv->reset);
+	}
+
+	return err;
+}
+
+static const struct phy_ops ath79_usb_phy_ops = {
+	.power_on	= ath79_usb_phy_power_on,
+	.power_off	= ath79_usb_phy_power_off,
+	.owner		= THIS_MODULE,
+};
+
+static int ath79_usb_phy_probe(struct platform_device *pdev)
+{
+	struct ath79_usb_phy *priv;
+	struct phy *phy;
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->reset = devm_reset_control_get(&pdev->dev, "usb-phy");
+	if (IS_ERR(priv->reset))
+		return PTR_ERR(priv->reset);
+
+	priv->no_suspend_override = devm_reset_control_get_optional(
+		&pdev->dev, "usb-suspend-override");
+	if (IS_ERR(priv->no_suspend_override))
+		return PTR_ERR(priv->no_suspend_override);
+
+	phy = devm_phy_create(&pdev->dev, NULL, &ath79_usb_phy_ops);
+	if (IS_ERR(phy))
+		return PTR_ERR(phy);
+
+	phy_set_drvdata(phy, priv);
+
+	return PTR_ERR_OR_ZERO(devm_of_phy_provider_register(
+				&pdev->dev, of_phy_simple_xlate));
+}
+
+static const struct of_device_id ath79_usb_phy_of_match[] = {
+	{ .compatible = "qca,ar7100-usb-phy" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, ath79_usb_phy_of_match);
+
+static struct platform_driver ath79_usb_phy_driver = {
+	.probe	= ath79_usb_phy_probe,
+	.driver = {
+		.of_match_table	= ath79_usb_phy_of_match,
+		.name		= "ath79-usb-phy",
+	}
+};
+module_platform_driver(ath79_usb_phy_driver);
+
+MODULE_DESCRIPTION("ATH79 USB PHY driver");
+MODULE_AUTHOR("Alban Bedel <albeu@free.fr>");
+MODULE_LICENSE("GPL");