[PATCH] extcon: add MAX3355 driver

[Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>]

MAX3355E chip integrates a charge pump and comparators to enable a system with
an integrated USB OTG dual-role transceiver to function as a USB OTG dual-role
device. In addition to sensing/controlling Vbus, the chip also passes thru the
ID signal from the USB OTG connector.  On some Renesas boards, this signal  is
just  fed into the SoC thru a GPIO pin -- there's no real OTG controller, only
host and gadget USB controllers sharing the same USB bus; however,  we'd  like
to allow host or gadget drivers to be loaded depending on the cable type, hence
the need for the MAX3355 extcon driver. The Vbus status signals are also wired
to GPIOs (however, we're not currently intested in them), the  OFFVBUS# signal
is controlled  by the host controllers, there's also the SHDN# signal wired to
GPIO, which should be high for normal operation.

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>

---
The patch is against the 'extcon-next' branch of the 'extcon.git' repo.

 Documentation/devicetree/bindings/extcon/extcon-max3355.txt |   21 ++
 drivers/extcon/Kconfig                                      |    6 
 drivers/extcon/Makefile                                     |    1 
 drivers/extcon/extcon-max3355.c                             |  122 ++++++++++++
 4 files changed, 150 insertions(+)

Index: extcon/Documentation/devicetree/bindings/extcon/extcon-max3355.txt
===================================================================
--- /dev/null
+++ extcon/Documentation/devicetree/bindings/extcon/extcon-max3355.txt
@@ -0,0 +1,21 @@
+MAX3355 USB OTG chip
+--------------------
+
+MAX3355 integrates a charge pump and comparators to enable a system with an
+integrated USB OTG dual-role transceiver to function as a USB OTG dual-role
+device.
+
+Required properties:
+- compatible: should be "maxim,max3355";
+- maxim,shdn-gpio: should contain a phandle and GPIO specifier for the GPIO pin
+  connected to the MAX3355's SHDN# pin;
+- maxim,id-gpio: should contain a phandle and GPIO specifier for the GPIO pin
+  connected to the MAX3355's ID_OUT pin.
+
+Example (Koelsch board):
+
+	usb-otg {
+		compatible = "maxim,max3355";
+		maxim,shdn-gpio = <&gpio2 4 GPIO_ACTIVE_LOW>;
+		maxim,id-gpio = <&gpio5 31 GPIO_ACTIVE_HIGH>;
+	};
Index: extcon/drivers/extcon/Kconfig
===================================================================
--- extcon.orig/drivers/extcon/Kconfig
+++ extcon/drivers/extcon/Kconfig
@@ -45,6 +45,12 @@ config EXTCON_MAX14577
 	  Maxim MAX14577/77836. The MAX14577/77836 MUIC is a USB port accessory
 	  detector and switch.
 
+config EXTCON_MAX3355
+	tristate "MAX3355 USB OTG EXTCON Support"
+	help
+	  Say Y here to enable support for the USB host detection by MAX3355
+	  OTG USB chip.
+
 config EXTCON_MAX77693
 	tristate "MAX77693 EXTCON Support"
 	depends on MFD_MAX77693 && INPUT
Index: extcon/drivers/extcon/Makefile
===================================================================
--- extcon.orig/drivers/extcon/Makefile
+++ extcon/drivers/extcon/Makefile
@@ -7,6 +7,7 @@ obj-$(CONFIG_EXTCON_ADC_JACK)	+= extcon-
 obj-$(CONFIG_EXTCON_ARIZONA)	+= extcon-arizona.o
 obj-$(CONFIG_EXTCON_GPIO)	+= extcon-gpio.o
 obj-$(CONFIG_EXTCON_MAX14577)	+= extcon-max14577.o
+obj-$(CONFIG_EXTCON_MAX3355)	+= extcon-max3355.o
 obj-$(CONFIG_EXTCON_MAX77693)	+= extcon-max77693.o
 obj-$(CONFIG_EXTCON_MAX8997)	+= extcon-max8997.o
 obj-$(CONFIG_EXTCON_PALMAS)	+= extcon-palmas.o
Index: extcon/drivers/extcon/extcon-max3355.c
===================================================================
--- /dev/null
+++ extcon/drivers/extcon/extcon-max3355.c
@@ -0,0 +1,122 @@
+/*
+ * MAX3355 USB OTG chip extcon driver
+ *
+ * Copyright (C) 2014 Cogent Embedded, Inc.
+ * Author: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ */
+
+#include <linux/extcon.h>
+#include <linux/gpio.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_gpio.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/workqueue.h>
+
+struct max3355_data {
+	struct extcon_dev *edev;
+	int id_gpio;
+};
+
+static const char *max3355_cable[] = {
+	[0] = "USB-HOST",
+	NULL,
+};
+
+static irqreturn_t max3355_id_irq(int irq, void *dev_id)
+{
+	struct max3355_data *data = dev_id;
+	int id = gpio_get_value(data->id_gpio);
+
+	extcon_set_cable_state(data->edev, "USB-HOST", !id);
+
+	return IRQ_HANDLED;
+}
+
+static int max3355_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct max3355_data *data;
+	int gpio, irq, ret;
+
+	data = devm_kzalloc(&pdev->dev, sizeof(struct max3355_data),
+			    GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->edev = devm_extcon_dev_allocate(&pdev->dev, max3355_cable);
+	if (IS_ERR(data->edev)) {
+		dev_err(&pdev->dev, "failed to allocate extcon device\n");
+		return PTR_ERR(data->edev);
+	}
+	data->edev->name = kstrdup(np->name, GFP_KERNEL);
+
+	gpio = of_get_named_gpio(np, "maxim,id-gpio", 0);
+	if (gpio < 0)
+		return gpio;
+	data->id_gpio = gpio;
+
+	gpio = of_get_named_gpio(np, "maxim,shdn-gpio", 0);
+	if (gpio < 0)
+		return gpio;
+
+	ret = devm_gpio_request_one(&pdev->dev, gpio, GPIOF_DIR_OUT |
+				    GPIOF_INIT_HIGH, pdev->name);
+	if (ret < 0)
+		return ret;
+
+	ret = devm_gpio_request_one(&pdev->dev, data->id_gpio, GPIOF_DIR_IN,
+				    pdev->name);
+	if (ret < 0)
+		return ret;
+
+	ret = devm_extcon_dev_register(&pdev->dev, data->edev);
+	if (ret < 0)
+		return ret;
+
+	irq = gpio_to_irq(data->id_gpio);
+	if (irq < 0)
+		return irq;
+
+	ret = devm_request_threaded_irq(&pdev->dev, irq, NULL, max3355_id_irq,
+					IRQF_TRIGGER_RISING |
+					IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
+					pdev->name, data);
+	if (ret < 0)
+		return ret;
+
+	platform_set_drvdata(pdev, data);
+
+	/* Perform initial detection */
+	max3355_id_irq(irq, data);
+
+	return 0;
+}
+
+static const struct of_device_id max3355_match_table[] = {
+	{ .compatible = "maxim,max3355", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, max3355_match_table);
+
+static struct platform_driver max3355_driver = {
+	.probe		= max3355_probe,
+	.driver		= {
+		.name	= "extcon-max3355",
+		.of_match_table = max3355_match_table,
+		.owner	= THIS_MODULE,
+	},
+};
+
+module_platform_driver(max3355_driver);
+
+MODULE_AUTHOR("Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>");
+MODULE_DESCRIPTION("MAX3355 extcon driver");
+MODULE_LICENSE("GPL v2");