[PATCH] extcon: 3gpio: add driver for USB OTG port controlled by 3 GPIOs

[Hans de Goede <hdegoede@redhat.com>]

From: David Cohen <david.a.cohen@intel.com>

Add an exntcon driver to for USB OTG ports controlled by 3 GPIOs used on
Intel Baytrail and Cherrytrail tablets.

Signed-off-by: David Cohen <david.a.cohen@intel.com>
[hdgoede@redhat.com: Port to current kernel, submit upstream]
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/extcon/Kconfig            |   7 ++
 drivers/extcon/Makefile           |   1 +
 drivers/extcon/extcon-3gpio_otg.c | 201 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 209 insertions(+)
 create mode 100644 drivers/extcon/extcon-3gpio_otg.c

diff --git a/drivers/extcon/Kconfig b/drivers/extcon/Kconfig
index 04788d9..1aaa64f 100644
--- a/drivers/extcon/Kconfig
+++ b/drivers/extcon/Kconfig
@@ -14,6 +14,13 @@ if EXTCON
 
 comment "Extcon Device Drivers"
 
+config EXTCON_3GPIO_OTG
+	tristate "3 GPIO USB OTG extcon driver"
+	depends on GPIOLIB || COMPILE_TEST
+	help
+	  Say Y here to enable extcon support for USB OTG ports controlled
+	  by 3 GPIOs used on Intel Baytrail and Cherrytrail tablets.
+
 config EXTCON_ADC_JACK
 	tristate "ADC Jack extcon support"
 	depends on IIO
diff --git a/drivers/extcon/Makefile b/drivers/extcon/Makefile
index 31a0a99..aa646fd 100644
--- a/drivers/extcon/Makefile
+++ b/drivers/extcon/Makefile
@@ -4,6 +4,7 @@
 
 obj-$(CONFIG_EXTCON)		+= extcon-core.o
 extcon-core-objs		+= extcon.o devres.o
+obj-$(CONFIG_EXTCON_3GPIO_OTG)	+= extcon-3gpio_otg.o
 obj-$(CONFIG_EXTCON_ADC_JACK)	+= extcon-adc-jack.o
 obj-$(CONFIG_EXTCON_ARIZONA)	+= extcon-arizona.o
 obj-$(CONFIG_EXTCON_AXP288)	+= extcon-axp288.o
diff --git a/drivers/extcon/extcon-3gpio_otg.c b/drivers/extcon/extcon-3gpio_otg.c
new file mode 100644
index 0000000..fc8b14d1
--- /dev/null
+++ b/drivers/extcon/extcon-3gpio_otg.c
@@ -0,0 +1,201 @@
+/*
+ * 3 GPIO USB OTG extcon driver
+ *
+ * Copyright (c) 2016) Hans de Goede <hdegoede@redhat.com>
+ *
+ * Based on android x86 kernel code which is:
+ *
+ * Copyright (c) 2014, Intel Corporation.
+ * Author: David Cohen <david.a.cohen@linux.intel.com>
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/acpi.h>
+#include <linux/extcon.h>
+#include <linux/gpio.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+
+#define DRV_NAME		"usb_otg_port"
+#define USB_OTG_GPIO_USB_ID	0
+#define USB_OTG_GPIO_VBUS_EN	1
+#define USB_OTG_GPIO_USB_MUX	2
+#define DEBOUNCE_TIME		msecs_to_jiffies(50)
+
+struct usb_otg {
+	struct device *dev;
+	struct extcon_dev *edev;
+	struct delayed_work work;
+	struct gpio_desc *gpio_usb_id;
+	struct gpio_desc *gpio_vbus_en;
+	struct gpio_desc *gpio_usb_mux;
+	int usb_id_irq;
+};
+
+static const unsigned int usb_otg_cable[] = {
+	EXTCON_USB_HOST,
+	EXTCON_NONE,
+};
+
+/*
+ * If id == 1, USB port should be set to peripheral
+ * if id == 0, 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 void usb_otg_set_port(struct usb_otg *otg, int id)
+{
+	int mux_val = id;
+	int vbus_val = !id;
+
+	if (!IS_ERR(otg->gpio_usb_mux))
+		gpiod_direction_output(otg->gpio_usb_mux, mux_val);
+
+	if (!IS_ERR(otg->gpio_vbus_en))
+		gpiod_direction_output(otg->gpio_vbus_en, vbus_val);
+}
+
+static void usb_otg_do_usb_id(struct work_struct *work)
+{
+	struct usb_otg *otg =
+		container_of(work, struct usb_otg, work.work);
+	int id = gpiod_get_value_cansleep(otg->gpio_usb_id);
+
+	dev_info(otg->dev, "USB PORT ID: %s\n", id ? "PERIPHERAL" : "HOST");
+
+	/*
+	 * id == 1: PERIPHERAL
+	 * id == 0: HOST
+	 */
+	usb_otg_set_port(otg, id);
+
+	/*
+	 * id == 0: HOST connected
+	 * id == 1: Host disconnected
+	 */
+	extcon_set_state_sync(otg->edev, EXTCON_USB_HOST, !id);
+}
+
+static irqreturn_t usb_otg_thread_isr(int irq, void *priv)
+{
+	struct usb_otg *otg = priv;
+
+	/* id changed, let the pin settle and then process it */
+	mod_delayed_work(system_wq, &otg->work, DEBOUNCE_TIME);
+
+	return IRQ_HANDLED;
+}
+
+static int usb_otg_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct usb_otg *otg;
+	int ret;
+
+	otg = devm_kzalloc(dev, sizeof(*otg), GFP_KERNEL);
+	if (!otg)
+		return -ENOMEM;
+
+	otg->dev = dev;
+	INIT_DELAYED_WORK(&otg->work, usb_otg_do_usb_id);
+
+	otg->gpio_usb_id = devm_gpiod_get_index(dev, "id",
+						USB_OTG_GPIO_USB_ID,
+						GPIOD_IN);
+	if (IS_ERR(otg->gpio_usb_id)) {
+		dev_err(dev, "can't request USB ID GPIO: ret = %ld\n",
+			PTR_ERR(otg->gpio_usb_id));
+		return PTR_ERR(otg->gpio_usb_id);
+	}
+
+	otg->usb_id_irq = gpiod_to_irq(otg->gpio_usb_id);
+	if (otg->usb_id_irq <= 0) {
+		dev_err(dev, "invalid USB ID IRQ: %d\n", otg->usb_id_irq);
+		return -EINVAL;
+	}
+
+	otg->gpio_vbus_en = devm_gpiod_get_index(dev, "vbus en",
+						 USB_OTG_GPIO_VBUS_EN,
+						 GPIOD_ASIS);
+	if (IS_ERR(otg->gpio_vbus_en))
+		dev_info(dev, "can't request VBUS EN GPIO, skipping it.\n");
+
+	otg->gpio_usb_mux = devm_gpiod_get_index(dev, "usb mux",
+						 USB_OTG_GPIO_USB_MUX,
+						 GPIOD_ASIS);
+	if (IS_ERR(otg->gpio_usb_mux))
+		dev_info(dev, "can't request USB MUX, skipping it.\n");
+
+	/* register extcon device */
+	otg->edev = devm_extcon_dev_allocate(dev, usb_otg_cable);
+	if (IS_ERR(otg->edev)) {
+		dev_err(dev, "failed to allocate extcon device\n");
+		return -ENOMEM;
+	}
+
+	ret = devm_extcon_dev_register(dev, otg->edev);
+	if (ret < 0) {
+		dev_err(dev, "failed to register extcon device: %d\n",
+			ret);
+		return ret;
+	}
+
+	ret = devm_request_threaded_irq(dev, otg->usb_id_irq,
+					NULL, usb_otg_thread_isr,
+					IRQF_SHARED | IRQF_ONESHOT |
+					IRQF_TRIGGER_RISING |
+					IRQF_TRIGGER_FALLING,
+					dev_name(dev), otg);
+	if (ret < 0) {
+		dev_err(dev, "can't request IRQ for USB ID GPIO: %d\n", ret);
+		return ret;
+	}
+
+	/* queue initial processing of id-pin */
+	queue_delayed_work(system_wq, &otg->work, 0);
+
+	platform_set_drvdata(pdev, otg);
+
+	return 0;
+}
+
+static int usb_otg_remove(struct platform_device *pdev)
+{
+	struct usb_otg *otg = platform_get_drvdata(pdev);
+
+	devm_free_irq(&pdev->dev, otg->usb_id_irq, otg);
+	cancel_delayed_work_sync(&otg->work);
+
+	return 0;
+}
+
+static struct acpi_device_id usb_otg_acpi_match[] = {
+	{ "INT3496" },
+	{ }
+};
+MODULE_DEVICE_TABLE(acpi, usb_otg_acpi_match);
+
+static struct platform_driver usb_otg_driver = {
+	.driver = {
+		.name = DRV_NAME,
+		.owner = THIS_MODULE,
+		.acpi_match_table = ACPI_PTR(usb_otg_acpi_match),
+	},
+	.probe = usb_otg_probe,
+	.remove = usb_otg_remove,
+};
+
+module_platform_driver(usb_otg_driver);
+
+MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
+MODULE_DESCRIPTION("3 GPIO USB OTG extcon driver");
+MODULE_LICENSE("GPL");
-- 
2.9.3