[PATCH v4 4/7] usb: mux: add driver for Intel gpio controlled port mux

[Lu Baolu]

In some Intel platforms, a single usb port is shared between USB host
and device controller. The shared port is under control of GPIO pins.

This patch adds the support for USB GPIO controlled port mux.

Signed-off-by: David Cohen <david.a.cohen@xxxxxxxxxxxxxxx>
Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
Reviewed-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
Reviewed-by: Felipe Balbi <balbi@xxxxxxxxxx>
Signed-off-by: Fengguang Wu <fengguang.wu@xxxxxxxxx>
---
 MAINTAINERS                      |   1 +
 drivers/usb/mux/Kconfig          |   9 +++
 drivers/usb/mux/Makefile         |   1 +
 drivers/usb/mux/intel-mux-gpio.c | 120 +++++++++++++++++++++++++++++++++++++++
 4 files changed, 131 insertions(+)
 create mode 100644 drivers/usb/mux/intel-mux-gpio.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 0dbee11..99bc198 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11405,6 +11405,7 @@ L:	linux-usb@xxxxxxxxxxxxxxx
 S:	Supported
 F:	include/linux/usb/intel-mux.h
 F:	drivers/usb/mux/intel-mux.c
+F:	drivers/usb/mux/intel-mux-gpio.c
 
 USB PRINTER DRIVER (usblp)
 M:	Pete Zaitcev <zaitcev@xxxxxxxxxx>
diff --git a/drivers/usb/mux/Kconfig b/drivers/usb/mux/Kconfig
index 62e2cc3..2b197c1 100644
--- a/drivers/usb/mux/Kconfig
+++ b/drivers/usb/mux/Kconfig
@@ -9,4 +9,13 @@ config INTEL_USB_MUX
 	  Common code for all Intel dual role port mux drivers. All Intel
 	  usb port mux drivers should select it.
 
+config INTEL_MUX_GPIO
+	tristate "Intel dual role port mux controlled by GPIOs"
+	depends on GPIOLIB
+	depends on X86 && ACPI
+	select INTEL_USB_MUX
+	help
+	  Say Y here to enable support for Intel dual role port mux
+	  controlled by GPIOs.
+
 endmenu
diff --git a/drivers/usb/mux/Makefile b/drivers/usb/mux/Makefile
index 84f0ae8..66f765c 100644
--- a/drivers/usb/mux/Makefile
+++ b/drivers/usb/mux/Makefile
@@ -2,3 +2,4 @@
 # Makefile for USB port mux drivers
 #
 obj-$(CONFIG_INTEL_USB_MUX)		+= intel-mux.o
+obj-$(CONFIG_INTEL_MUX_GPIO)		+= intel-mux-gpio.o
diff --git a/drivers/usb/mux/intel-mux-gpio.c b/drivers/usb/mux/intel-mux-gpio.c
new file mode 100644
index 0000000..df71283
--- /dev/null
+++ b/drivers/usb/mux/intel-mux-gpio.c
@@ -0,0 +1,120 @@
+/*
+ * USB Dual Role Port Mux driver controlled by gpios
+ *
+ * Copyright (c) 2016, Intel Corporation.
+ * Author: David Cohen <david.a.cohen@xxxxxxxxxxxxxxx>
+ * Author: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/acpi.h>
+#include <linux/gpio.h>
+#include <linux/platform_device.h>
+#include <linux/usb/intel-mux.h>
+
+struct vuport {
+	struct device *dev;
+	struct gpio_desc *gpio_vbus_en;
+	struct gpio_desc *gpio_usb_mux;
+};
+
+static struct vuport *vup;
+
+/*
+ * id == 0, HOST connected, USB port should be set to peripheral
+ * id == 1, HOST disconnected, USB port should be set to host
+ *
+ * Peripheral: set USB mux to peripheral and disable VBUS
+ * Host: set USB mux to host and enable VBUS
+ */
+static inline int vuport_set_port(struct device *dev, int id)
+{
+	dev_dbg(dev, "USB PORT ID: %s\n", id ? "HOST" : "PERIPHERAL");
+
+	gpiod_set_value_cansleep(vup->gpio_usb_mux, !id);
+	gpiod_set_value_cansleep(vup->gpio_vbus_en, id);
+
+	return 0;
+}
+
+static int vuport_cable_set(struct device *dev)
+{
+	return vuport_set_port(dev, 1);
+}
+
+static int vuport_cable_unset(struct device *dev)
+{
+	return vuport_set_port(dev, 0);
+}
+
+static int vuport_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+
+	vup = devm_kzalloc(dev, sizeof(*vup), GFP_KERNEL);
+	if (!vup)
+		return -ENOMEM;
+
+	/* retrieve vbus and mux gpios */
+	vup->gpio_vbus_en = devm_gpiod_get_optional(dev,
+				"vbus_en", GPIOD_ASIS);
+	if (IS_ERR(vup->gpio_vbus_en))
+		return PTR_ERR(vup->gpio_vbus_en);
+
+	vup->gpio_usb_mux = devm_gpiod_get_optional(dev,
+				"usb_mux", GPIOD_ASIS);
+	if (IS_ERR(vup->gpio_usb_mux))
+		return PTR_ERR(vup->gpio_usb_mux);
+
+	vup->dev = dev;
+
+	return intel_usb_mux_bind_cable(dev, NULL, "USB-HOST",
+					vuport_cable_set,
+					vuport_cable_unset);
+}
+
+static int vuport_remove(struct platform_device *pdev)
+{
+	return intel_usb_mux_unbind_cable(&pdev->dev);
+}
+
+#ifdef CONFIG_PM_SLEEP
+/*
+ * In case a micro A cable was plugged in while device was sleeping,
+ * we missed the interrupt. We need to poll usb id gpio when waking the
+ * driver to detect the missed event.
+ * We use 'complete' callback to give time to all extcon listeners to
+ * resume before we send new events.
+ */
+static const struct dev_pm_ops vuport_pm_ops = {
+	.complete = intel_usb_mux_complete,
+};
+#endif
+
+static const struct platform_device_id vuport_platform_ids[] = {
+	{ .name = "intel-mux-gpio", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(platform, vuport_platform_ids);
+
+static struct platform_driver vuport_driver = {
+	.driver = {
+		.name = "intel-mux-gpio",
+#ifdef CONFIG_PM_SLEEP
+		.pm = &vuport_pm_ops,
+#endif
+	},
+	.probe = vuport_probe,
+	.remove = vuport_remove,
+	.id_table = vuport_platform_ids,
+};
+
+module_platform_driver(vuport_driver);
+
+MODULE_AUTHOR("David Cohen <david.a.cohen@xxxxxxxxxxxxxxx>");
+MODULE_AUTHOR("Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>");
+MODULE_DESCRIPTION("Intel USB gpio mux driver");
+MODULE_LICENSE("GPL v2");
-- 
2.1.4