[PATCH v2] extcon: otg_gpio: add driver for USB OTG port controlled by GPIO(s)

[David Cohen <david.a.cohen@linux.intel.com>]

Some Intel platforms have an USB OTG port fully (or partially)
controlled by GPIOs:

(1) USB ID is connected directly to a pulled up GPIO.

Optionally:
(2) VBUS is enabled/disabled by a GPIO
(3) Platform has 2 USB controllers connected to same port: one for
    device and one for host role. D+/- are switched between phys.
    according to this GPIO level.

This driver configures USB OTG port for device or host role according to
USB ID value.
 - If USB ID's GPIO level is low, OTG port is configured for host role
   by sourcing VBUS and switching D+/- to host phy.
 - If USB ID's GPIO level is high, by standard, the OTG port is
   configured for device role by not sourcing VBUS and switching D+/- to
   device controller.

Signed-off-by: David Cohen <david.a.cohen@linux.intel.com>
---

Hi,

Since splitting this driver into smaller pieces would result in ugly fixes WRT
ACPI, I'm resending the same approach.
This time I addressed all comments I got from RFC version.

As always, comments are welcome.

Br, David
---

 drivers/extcon/Kconfig           |   8 ++
 drivers/extcon/Makefile          |   1 +
 drivers/extcon/extcon-otg_gpio.c | 186 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 195 insertions(+)
 create mode 100644 drivers/extcon/extcon-otg_gpio.c

diff --git a/drivers/extcon/Kconfig b/drivers/extcon/Kconfig
index 6a1f7de6fa54..986ca7da9c1b 100644
--- a/drivers/extcon/Kconfig
+++ b/drivers/extcon/Kconfig
@@ -63,6 +63,14 @@ config EXTCON_MAX8997
 	  Maxim MAX8997 PMIC. The MAX8997 MUIC is a USB port accessory
 	  detector and switch.
 
+config EXTCON_OTG_GPIO
+	tristate "VIRTUAL USB OTG PORT support"
+	depends on GPIOLIB && ACPI
+	help
+	  Say Y here to enable support for virtual USB OTG port device
+	  controlled by GPIOs. This driver can be used when at least USB ID pin
+	  is connected directly to GPIO.
+
 config EXTCON_PALMAS
 	tristate "Palmas USB EXTCON support"
 	depends on MFD_PALMAS
diff --git a/drivers/extcon/Makefile b/drivers/extcon/Makefile
index 0370b42e5a27..0d5b152b51ea 100644
--- a/drivers/extcon/Makefile
+++ b/drivers/extcon/Makefile
@@ -9,6 +9,7 @@ obj-$(CONFIG_EXTCON_GPIO)	+= extcon-gpio.o
 obj-$(CONFIG_EXTCON_MAX14577)	+= extcon-max14577.o
 obj-$(CONFIG_EXTCON_MAX77693)	+= extcon-max77693.o
 obj-$(CONFIG_EXTCON_MAX8997)	+= extcon-max8997.o
+obj-$(CONFIG_EXTCON_OTG_GPIO)	+= extcon-otg_gpio.o
 obj-$(CONFIG_EXTCON_PALMAS)	+= extcon-palmas.o
 obj-$(CONFIG_EXTCON_RT8973A)	+= extcon-rt8973a.o
 obj-$(CONFIG_EXTCON_SM5502)	+= extcon-sm5502.o
diff --git a/drivers/extcon/extcon-otg_gpio.c b/drivers/extcon/extcon-otg_gpio.c
new file mode 100644
index 000000000000..7dfa2c15b562
--- /dev/null
+++ b/drivers/extcon/extcon-otg_gpio.c
@@ -0,0 +1,186 @@
+/*
+ * Virtual USB OTG Port driver controlled by gpios
+ *
+ * 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/consumer.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+#define DRV_NAME	"usb_otg_port"
+
+struct vuport {
+	struct device *dev;
+	struct gpio_desc *gpio_vbus_en;
+	struct gpio_desc *gpio_usb_id;
+	struct gpio_desc *gpio_usb_mux;
+
+	struct extcon_dev edev;
+};
+
+static const char *vuport_extcon_cable[] = {
+	[0] = "USB-Host",
+	NULL,
+};
+
+/*
+ * 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 vuport_set_port(struct vuport *vup, int id)
+{
+	int mux_val = id;
+	int vbus_val = !id;
+
+	if (!IS_ERR(vup->gpio_usb_mux))
+		gpiod_direction_output(vup->gpio_usb_mux, mux_val);
+
+	if (!IS_ERR(vup->gpio_vbus_en))
+		gpiod_direction_output(vup->gpio_vbus_en, vbus_val);
+}
+
+static void vuport_do_usb_id(struct vuport *vup)
+{
+	int id = gpiod_get_value(vup->gpio_usb_id);
+
+	dev_info(vup->dev, "USB PORT ID: %s\n", id ? "PERIPHERAL" : "HOST");
+
+	/*
+	 * id == 1: PERIPHERAL
+	 * id == 0: HOST
+	 */
+	vuport_set_port(vup, id);
+
+	/*
+	 * id == 0: HOST connected
+	 * id == 1: Host disconnected
+	 */
+	extcon_set_cable_state(&vup->edev, "USB-Host", !id);
+}
+
+static irqreturn_t vuport_thread_isr(int irq, void *priv)
+{
+	struct vuport *vup = priv;
+
+	vuport_do_usb_id(vup);
+	return IRQ_HANDLED;
+}
+
+#define VUPORT_GPIO_USB_ID	0
+#define VUPORT_GPIO_VBUS_EN	1
+#define VUPORT_GPIO_USB_MUX	2
+static int vuport_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct vuport *vup;
+	int ret;
+
+	vup = devm_kzalloc(dev, sizeof(*vup), GFP_KERNEL);
+	if (!vup) {
+		dev_err(dev, "cannot allocate private data\n");
+		return -ENOMEM;
+	}
+	vup->dev = dev;
+
+	vup->gpio_usb_id = devm_gpiod_get_index(dev, "id", VUPORT_GPIO_USB_ID);
+	if (IS_ERR(vup->gpio_usb_id)) {
+		dev_err(dev, "cannot request USB ID GPIO: ret = %ld\n",
+			PTR_ERR(vup->gpio_usb_id));
+		return PTR_ERR(vup->gpio_usb_id);
+	}
+
+	ret = gpiod_direction_input(vup->gpio_usb_id);
+	if (ret < 0) {
+		dev_err(dev, "cannot set input direction to USB ID GPIO: ret = %d\n",
+			ret);
+		return ret;
+	}
+
+	vup->gpio_vbus_en = devm_gpiod_get_index(dev, "vbus en",
+						 VUPORT_GPIO_VBUS_EN);
+	if (IS_ERR(vup->gpio_vbus_en))
+		dev_dbg(dev, "cannot request VBUS EN GPIO, skipping it.\n");
+
+	vup->gpio_usb_mux = devm_gpiod_get_index(dev, "usb mux",
+						 VUPORT_GPIO_USB_MUX);
+	if (IS_ERR(vup->gpio_usb_mux))
+		dev_dbg(dev, "cannot request USB USB MUX, skipping it.\n");
+
+	/* register extcon device */
+	vup->edev.dev.parent = dev;
+	vup->edev.supported_cable = vuport_extcon_cable;
+	ret = extcon_dev_register(&vup->edev);
+	if (ret < 0) {
+		dev_err(dev, "failed to register extcon device: ret = %d\n",
+			ret);
+		return ret;
+	}
+
+	ret = devm_request_threaded_irq(dev, gpiod_to_irq(vup->gpio_usb_id),
+					NULL, vuport_thread_isr,
+					IRQF_SHARED | IRQF_TRIGGER_RISING |
+					IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
+					dev_name(dev), vup);
+	if (ret < 0) {
+		dev_err(dev, "cannot request IRQ for USB ID GPIO: ret = %d\n",
+			ret);
+		goto irq_err;
+	}
+	vuport_do_usb_id(vup);
+
+	platform_set_drvdata(pdev, vup);
+
+	dev_dbg(dev, "driver successfully probed\n");
+
+	return 0;
+
+irq_err:
+	extcon_dev_unregister(&vup->edev);
+
+	return ret;
+}
+
+static int vuport_remove(struct platform_device *pdev)
+{
+	struct vuport *vup = platform_get_drvdata(pdev);
+
+	extcon_dev_unregister(&vup->edev);
+	return 0;
+}
+
+static struct acpi_device_id vuport_acpi_match[] = {
+	{ "INT3496" },
+	{ }
+};
+MODULE_DEVICE_TABLE(acpi, vuport_acpi_match);
+
+static struct platform_driver vuport_driver = {
+	.driver = {
+		.name = DRV_NAME,
+		.acpi_match_table = ACPI_PTR(vuport_acpi_match),
+	},
+	.probe = vuport_probe,
+	.remove = vuport_remove,
+};
+
+module_platform_driver(vuport_driver);
+
+MODULE_LICENSE("GPLv2");
+MODULE_AUTHOR("David Cohen <david.a.cohen@linux.intel.com>");
-- 
2.1.1