extcon: add Maxim MAX3355 driver

Maxim Integrated MAX3355E chip integrates a charge pump and comparators to
enable a system with an integrated USB OTG dual-role transceiver to
function as an 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 aren't currently interested in them), the OFFVBUS# signal is
controlled by the host controllers, there's also the SHDN# signal wired to
a GPIO, it should be driven high for the normal operation.

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Acked-by: Chanwoo Choi <cw00.choi@samsung.com>
Acked-by: Rob Herring <robh@kernel.org>
[cw00.choi: Add the GPIOLIB dependency]
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>

1 files changed, 146 insertions, 0 deletions

diff --git a/drivers/extcon/extcon-max3355.c b/drivers/extcon/extcon-max3355.c
new file mode 100644
index 000000000000..c24abec5d06c
--- /dev/null
+++ b/drivers/extcon/extcon-max3355.c
@@ -0,0 +1,146 @@
+/*
+ * Maxim Integrated MAX3355 USB OTG chip extcon driver
+ *
+ * Copyright (C)  2014-2015 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/gpio/consumer.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+struct max3355_data {
+	struct extcon_dev *edev;
+	struct gpio_desc *id_gpiod;
+	struct gpio_desc *shdn_gpiod;
+};
+
+static const unsigned int max3355_cable[] = {
+	EXTCON_USB,
+	EXTCON_USB_HOST,
+	EXTCON_NONE,
+};
+
+static irqreturn_t max3355_id_irq(int irq, void *dev_id)
+{
+	struct max3355_data *data = dev_id;
+	int id = gpiod_get_value_cansleep(data->id_gpiod);
+
+	if (id) {
+		/*
+		 * ID = 1 means USB HOST cable detached.
+		 * As we don't have event for USB peripheral cable attached,
+		 * we simulate USB peripheral attach here.
+		 */
+		extcon_set_cable_state_(data->edev, EXTCON_USB_HOST, false);
+		extcon_set_cable_state_(data->edev, EXTCON_USB, true);
+	} else {
+		/*
+		 * ID = 0 means USB HOST cable attached.
+		 * As we don't have event for USB peripheral cable detached,
+		 * we simulate USB peripheral detach here.
+		 */
+		extcon_set_cable_state_(data->edev, EXTCON_USB, false);
+		extcon_set_cable_state_(data->edev, EXTCON_USB_HOST, true);
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int max3355_probe(struct platform_device *pdev)
+{
+	struct max3355_data *data;
+	struct gpio_desc *gpiod;
+	int irq, err;
+
+	data = devm_kzalloc(&pdev->dev, sizeof(struct max3355_data),
+			    GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	gpiod = devm_gpiod_get(&pdev->dev, "id", GPIOD_IN);
+	if (IS_ERR(gpiod)) {
+		dev_err(&pdev->dev, "failed to get ID_OUT GPIO\n");
+		return PTR_ERR(gpiod);
+	}
+	data->id_gpiod = gpiod;
+
+	gpiod = devm_gpiod_get(&pdev->dev, "maxim,shdn", GPIOD_OUT_HIGH);
+	if (IS_ERR(gpiod)) {
+		dev_err(&pdev->dev, "failed to get SHDN# GPIO\n");
+		return PTR_ERR(gpiod);
+	}
+	data->shdn_gpiod = gpiod;
+
+	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);
+	}
+
+	err = devm_extcon_dev_register(&pdev->dev, data->edev);
+	if (err < 0) {
+		dev_err(&pdev->dev, "failed to register extcon device\n");
+		return err;
+	}
+
+	irq = gpiod_to_irq(data->id_gpiod);
+	if (irq < 0) {
+		dev_err(&pdev->dev, "failed to translate ID_OUT GPIO to IRQ\n");
+		return irq;
+	}
+
+	err = devm_request_threaded_irq(&pdev->dev, irq, NULL, max3355_id_irq,
+					IRQF_ONESHOT | IRQF_NO_SUSPEND |
+					IRQF_TRIGGER_RISING |
+					IRQF_TRIGGER_FALLING,
+					pdev->name, data);
+	if (err < 0) {
+		dev_err(&pdev->dev, "failed to request ID_OUT IRQ\n");
+		return err;
+	}
+
+	platform_set_drvdata(pdev, data);
+
+	/* Perform initial detection */
+	max3355_id_irq(irq, data);
+
+	return 0;
+}
+
+static int max3355_remove(struct platform_device *pdev)
+{
+	struct max3355_data *data = platform_get_drvdata(pdev);
+
+	gpiod_set_value_cansleep(data->shdn_gpiod, 0);
+
+	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,
+	.remove		= max3355_remove,
+	.driver		= {
+		.name	= "extcon-max3355",
+		.of_match_table = max3355_match_table,
+	},
+};
+
+module_platform_driver(max3355_driver);
+
+MODULE_AUTHOR("Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>");
+MODULE_DESCRIPTION("Maxim MAX3355 extcon driver");
+MODULE_LICENSE("GPL v2");