extcon: int3496: Add Intel INT3496 ACPI device extcon driver

Add an extcon driver for USB OTG ports controlled by an Intel INT3496
ACPI device (e.g. Baytrail, Cherrytrail devices).
Signed-off-by: David Cohen <david.a.cohen@intel.com>
[hdgoede@redhat.com: Port to current kernel, cleanup, submit upstream]
[hdgoede@redhat.com: Add Documentation/extcon/intel-int3496.txt]
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>

Documentation/extcon/intel-int3496.txt

+Intel INT3496 ACPI device extcon driver documentation
+-----------------------------------------------------
+
+The Intel INT3496 ACPI device extcon driver is a driver for ACPI
+devices with an acpi-id of INT3496, such as found for example on
+Intel Baytrail and Cherrytrail tablets.
+
+This ACPI device describes how the OS can read the id-pin of the devices'
+USB-otg port, as well as how it optionally can enable Vbus output on the
+otg port and how it can optionally control the muxing of the data pins
+between an USB host and an USB peripheral controller.
+
+The ACPI devices exposes this functionality by returning an array with up
+to 3 gpio descriptors from its ACPI _CRS (Current Resource Settings) call:
+
+Index 0: The input gpio for the id-pin, this is always present and valid
+Index 1: The output gpio for enabling Vbus output from the device to the otg
+         port, write 1 to enable the Vbus output (this gpio descriptor may
+         be absent or invalid)
+Index 2: The output gpio for muxing of the data pins between the USB host and
+         the USB peripheral controller, write 1 to mux to the peripheral
+         controller

drivers/extcon/Kconfig

@@ -42,6 +42,16 @@ config EXTCON_GPIO
 	  Say Y here to enable GPIO based extcon support. Note that GPIO
 	  extcon supports single state per extcon instance.
 
+config EXTCON_INTEL_INT3496
+	tristate "Intel INT3496 ACPI device extcon driver"
+	depends on GPIOLIB && ACPI
+	help
+	  Say Y here to enable extcon support for USB OTG ports controlled by
+	  an Intel INT3496 ACPI device.
+
+	  This ACPI device is typically found on Intel Baytrail or Cherrytrail
+	  based tablets, or other Baytrail / Cherrytrail devices.
+
 config EXTCON_MAX14577
 	tristate "Maxim MAX14577/77836 EXTCON Support"
 	depends on MFD_MAX14577

drivers/extcon/Makefile

@@ -8,6 +8,7 @@ obj-$(CONFIG_EXTCON_ADC_JACK)	+= extcon-adc-jack.o
 obj-$(CONFIG_EXTCON_ARIZONA)	+= extcon-arizona.o
 obj-$(CONFIG_EXTCON_AXP288)	+= extcon-axp288.o
 obj-$(CONFIG_EXTCON_GPIO)	+= extcon-gpio.o
+obj-$(CONFIG_EXTCON_INTEL_INT3496) += extcon-intel-int3496.o
 obj-$(CONFIG_EXTCON_MAX14577)	+= extcon-max14577.o
 obj-$(CONFIG_EXTCON_MAX3355)	+= extcon-max3355.o
 obj-$(CONFIG_EXTCON_MAX77693)	+= extcon-max77693.o

drivers/extcon/extcon-intel-int3496.c

+/*
+ * Intel INT3496 ACPI device 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/module.h>
+#include <linux/platform_device.h>
+
+#define INT3496_GPIO_USB_ID	0
+#define INT3496_GPIO_VBUS_EN	1
+#define INT3496_GPIO_USB_MUX	2
+#define DEBOUNCE_TIME		msecs_to_jiffies(50)
+
+struct int3496_data {
+	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 int3496_cable[] = {
+	EXTCON_USB_HOST,
+	EXTCON_NONE,
+};
+
+static void int3496_do_usb_id(struct work_struct *work)
+{
+	struct int3496_data *data =
+		container_of(work, struct int3496_data, work.work);
+	int id = gpiod_get_value_cansleep(data->gpio_usb_id);
+
+	/* id == 1: PERIPHERAL, id == 0: HOST */
+	dev_dbg(data->dev, "Connected %s cable\n", id ? "PERIPHERAL" : "HOST");
+
+	/*
+	 * Peripheral: set USB mux to peripheral and disable VBUS
+	 * Host: set USB mux to host and enable VBUS
+	 */
+	if (!IS_ERR(data->gpio_usb_mux))
+		gpiod_direction_output(data->gpio_usb_mux, id);
+
+	if (!IS_ERR(data->gpio_vbus_en))
+		gpiod_direction_output(data->gpio_vbus_en, !id);
+
+	extcon_set_state_sync(data->edev, EXTCON_USB_HOST, !id);
+}
+
+static irqreturn_t int3496_thread_isr(int irq, void *priv)
+{
+	struct int3496_data *data = priv;
+
+	/* Let the pin settle before processing it */
+	mod_delayed_work(system_wq, &data->work, DEBOUNCE_TIME);
+
+	return IRQ_HANDLED;
+}
+
+static int int3496_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct int3496_data *data;
+	int ret;
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->dev = dev;
+	INIT_DELAYED_WORK(&data->work, int3496_do_usb_id);
+
+	data->gpio_usb_id = devm_gpiod_get_index(dev, "id",
+						INT3496_GPIO_USB_ID,
+						GPIOD_IN);
+	if (IS_ERR(data->gpio_usb_id)) {
+		ret = PTR_ERR(data->gpio_usb_id);
+		dev_err(dev, "can't request USB ID GPIO: %d\n", ret);
+		return ret;
+	}
+
+	data->usb_id_irq = gpiod_to_irq(data->gpio_usb_id);
+	if (data->usb_id_irq <= 0) {
+		dev_err(dev, "can't get USB ID IRQ: %d\n", data->usb_id_irq);
+		return -EINVAL;
+	}
+
+	data->gpio_vbus_en = devm_gpiod_get_index(dev, "vbus en",
+						 INT3496_GPIO_VBUS_EN,
+						 GPIOD_ASIS);
+	if (IS_ERR(data->gpio_vbus_en))
+		dev_info(dev, "can't request VBUS EN GPIO\n");
+
+	data->gpio_usb_mux = devm_gpiod_get_index(dev, "usb mux",
+						 INT3496_GPIO_USB_MUX,
+						 GPIOD_ASIS);
+	if (IS_ERR(data->gpio_usb_mux))
+		dev_info(dev, "can't request USB MUX GPIO\n");
+
+	/* register extcon device */
+	data->edev = devm_extcon_dev_allocate(dev, int3496_cable);
+	if (IS_ERR(data->edev))
+		return -ENOMEM;
+
+	ret = devm_extcon_dev_register(dev, data->edev);
+	if (ret < 0) {
+		dev_err(dev, "can't register extcon device: %d\n", ret);
+		return ret;
+	}
+
+	ret = devm_request_threaded_irq(dev, data->usb_id_irq,
+					NULL, int3496_thread_isr,
+					IRQF_SHARED | IRQF_ONESHOT |
+					IRQF_TRIGGER_RISING |
+					IRQF_TRIGGER_FALLING,
+					dev_name(dev), data);
+	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, &data->work, 0);
+
+	platform_set_drvdata(pdev, data);
+
+	return 0;
+}
+
+static int int3496_remove(struct platform_device *pdev)
+{
+	struct int3496_data *data = platform_get_drvdata(pdev);
+
+	devm_free_irq(&pdev->dev, data->usb_id_irq, data);
+	cancel_delayed_work_sync(&data->work);
+
+	return 0;
+}
+
+static struct acpi_device_id int3496_acpi_match[] = {
+	{ "INT3496" },
+	{ }
+};
+MODULE_DEVICE_TABLE(acpi, int3496_acpi_match);
+
+static struct platform_driver int3496_driver = {
+	.driver = {
+		.name = "intel-int3496",
+		.acpi_match_table = int3496_acpi_match,
+	},
+	.probe = int3496_probe,
+	.remove = int3496_remove,
+};
+
+module_platform_driver(int3496_driver);
+
+MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
+MODULE_DESCRIPTION("Intel INT3496 ACPI device extcon driver");
+MODULE_LICENSE("GPL");