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From:   Michael Auchter <michael.auchter@ni.com>
To:     MyungJoo Ham <myungjoo.ham@samsung.com>,
        Chanwoo Choi <cw00.choi@samsung.com>
Cc:     Michael Auchter <michael.auchter@ni.com>,
        linux-kernel@vger.kernel.org
Subject: [PATCH 1/2] extcon: add driver for TI TUSB320
Date:   Thu,  8 Oct 2020 17:39:27 -0500
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This patch adds an extcon driver for the TI TUSB320 USB Type-C device.
This can be used to detect whether the port is configured as a
downstream or upstream facing port.

Signed-off-by: Michael Auchter <michael.auchter@ni.com>
---
 drivers/extcon/Kconfig               |   7 ++
 drivers/extcon/Makefile              |   1 +
 drivers/extcon/extcon-usbc-tusb320.c | 180 +++++++++++++++++++++++++++
 3 files changed, 188 insertions(+)
 create mode 100644 drivers/extcon/extcon-usbc-tusb320.c

diff --git a/drivers/extcon/Kconfig b/drivers/extcon/Kconfig
index aac507bff135..241acaf8b882 100644
--- a/drivers/extcon/Kconfig
+++ b/drivers/extcon/Kconfig
@@ -186,4 +186,11 @@ config EXTCON_USBC_CROS_EC
 	  Say Y here to enable USB Type C cable detection extcon support when
 	  using Chrome OS EC based USB Type-C ports.
 
+config EXTCON_USBC_TUSB320
+	tristate "TI TUSB320 USB-C extcon support"
+	depends on GPIOLIB || COMPILE_TEST
+	help
+	  Say Y here to enable support for USB Type C cable detection extcon
+	  support using a TUSB320.
+
 endif
diff --git a/drivers/extcon/Makefile b/drivers/extcon/Makefile
index 52096fd8a216..fe10a1b7d18b 100644
--- a/drivers/extcon/Makefile
+++ b/drivers/extcon/Makefile
@@ -25,3 +25,4 @@ obj-$(CONFIG_EXTCON_RT8973A)	+= extcon-rt8973a.o
 obj-$(CONFIG_EXTCON_SM5502)	+= extcon-sm5502.o
 obj-$(CONFIG_EXTCON_USB_GPIO)	+= extcon-usb-gpio.o
 obj-$(CONFIG_EXTCON_USBC_CROS_EC) += extcon-usbc-cros-ec.o
+obj-$(CONFIG_EXTCON_USBC_TUSB320) += extcon-usbc-tusb320.o
diff --git a/drivers/extcon/extcon-usbc-tusb320.c b/drivers/extcon/extcon-usbc-tusb320.c
new file mode 100644
index 000000000000..217d6f416ff6
--- /dev/null
+++ b/drivers/extcon/extcon-usbc-tusb320.c
@@ -0,0 +1,180 @@
+// SPDX-License-Identifier: GPL-2.0
+/**
+ * drivers/extcon/extcon-tusb320.c - TUSB320 extcon driver
+ *
+ * Copyright (C) 2020 National Instruments Corporation
+ * Author: Michael Auchter <michael.auchter@ni.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/extcon-provider.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/i2c.h>
+#include <linux/irq.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/workqueue.h>
+
+#define TUSB320_REG_9 0x9
+#define TUSB320_REG_9_INTERRUPT_STATUS BIT(4)
+#define TUSB320_REG_9_GET_ATTACHED_STATE(reg) (((reg) >> 6) & 0x3)
+#define TUSB320_REG_9_GET_CABLE_DIR(reg) (((reg) >> 5) & 1)
+#define TUSB320_ATTACHED_STATE_NONE 0x0
+#define TUSB320_ATTACHED_STATE_DFP  0x1
+#define TUSB320_ATTACHED_STATE_UFP  0x2
+#define TUSB320_ATTACHED_STATE_ACC  0x3
+
+static const char * const tusb_attached_states[] = {
+	[TUSB320_ATTACHED_STATE_NONE] = "not attached",
+	[TUSB320_ATTACHED_STATE_DFP]  = "downstream facing port",
+	[TUSB320_ATTACHED_STATE_UFP]  = "upstream facing port",
+	[TUSB320_ATTACHED_STATE_ACC]  = "accessory",
+};
+
+static const unsigned int tusb320_extcon_cable[] = {
+	EXTCON_USB,
+	EXTCON_USB_HOST,
+	EXTCON_NONE,
+};
+
+static int tusb320_check_signature(struct i2c_client *client)
+{
+	static const char sig[] = { '\0', 'T', 'U', 'S', 'B', '3', '2', '0' };
+	int i, ret;
+
+	for (i = 0; i < sizeof(sig); i++) {
+		ret = i2c_smbus_read_byte_data(client, sizeof(sig) - 1 - i);
+		if (ret < 0)
+			return ret;
+		if (ret != sig[i]) {
+			dev_err(&client->dev, "signature mismatch!\n");
+			return -ENODEV;
+		}
+	}
+
+	return 0;
+}
+
+static irqreturn_t tusb320_irq_handler(int irq, void *dev_id)
+{
+	struct i2c_client *client = dev_id;
+	struct extcon_dev *edev = i2c_get_clientdata(client);
+	int reg, state, polarity;
+
+	reg = i2c_smbus_read_byte_data(client, TUSB320_REG_9);
+	if (reg < 0) {
+		dev_err(&client->dev, "error during i2c read: %d\n", reg);
+		return IRQ_NONE;
+	}
+
+	if (!(reg & TUSB320_REG_9_INTERRUPT_STATUS))
+		return IRQ_NONE;
+
+	state = TUSB320_REG_9_GET_ATTACHED_STATE(reg);
+	polarity = TUSB320_REG_9_GET_CABLE_DIR(reg);
+
+	dev_dbg(&client->dev, "attached state: %s, polarity: %d\n",
+		tusb_attached_states[state], polarity);
+
+	extcon_set_state(edev, EXTCON_USB,
+			 state == TUSB320_ATTACHED_STATE_UFP);
+	extcon_set_state(edev, EXTCON_USB_HOST,
+			 state == TUSB320_ATTACHED_STATE_DFP);
+	extcon_set_property(edev, EXTCON_USB,
+			    EXTCON_PROP_USB_TYPEC_POLARITY,
+			    (union extcon_property_value)polarity);
+	extcon_set_property(edev, EXTCON_USB_HOST,
+			    EXTCON_PROP_USB_TYPEC_POLARITY,
+			    (union extcon_property_value)polarity);
+	extcon_sync(edev, EXTCON_USB);
+	extcon_sync(edev, EXTCON_USB_HOST);
+
+	i2c_smbus_write_byte_data(client, TUSB320_REG_9, reg);
+
+	return IRQ_HANDLED;
+}
+
+static int tusb320_extcon_probe(struct i2c_client *client,
+				const struct i2c_device_id *id)
+{
+	struct extcon_dev *edev;
+	int ret;
+
+	ret = tusb320_check_signature(client);
+	if (ret)
+		return ret;
+
+	edev = devm_extcon_dev_allocate(&client->dev, tusb320_extcon_cable);
+	if (IS_ERR(edev)) {
+		dev_err(&client->dev, "failed to allocate extcon device\n");
+		return -ENOMEM;
+	}
+	i2c_set_clientdata(client, edev);
+
+	ret = devm_extcon_dev_register(&client->dev, edev);
+	if (ret < 0) {
+		dev_err(&client->dev, "failed to register extcon device\n");
+		return ret;
+	}
+
+	extcon_set_property_capability(edev, EXTCON_USB,
+				       EXTCON_PROP_USB_TYPEC_POLARITY);
+	extcon_set_property_capability(edev, EXTCON_USB_HOST,
+				       EXTCON_PROP_USB_TYPEC_POLARITY);
+
+	/* update initial state */
+	tusb320_irq_handler(client->irq, client);
+
+	ret = devm_request_threaded_irq(&client->dev, client->irq,
+					NULL, tusb320_irq_handler,
+					IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
+					dev_name(&client->dev), client);
+
+	return ret;
+}
+
+static const struct of_device_id tusb320_extcon_dt_match[] = {
+	{ .compatible = "ti,tusb320", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, tusb320_extcon_dt_match);
+
+static const struct i2c_device_id tusb320_i2c_id[] = {
+	{ "tusb320", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, tusb320_i2c_id);
+
+static struct i2c_driver tusb320_extcon_driver = {
+	.probe		= tusb320_extcon_probe,
+	.driver		= {
+		.name	= "extcon-tusb320",
+		.of_match_table = tusb320_extcon_dt_match,
+	},
+};
+
+static int __init tusb320_init(void)
+{
+	return i2c_add_driver(&tusb320_extcon_driver);
+}
+subsys_initcall(tusb320_init);
+
+static void __exit tusb320_exit(void)
+{
+	i2c_del_driver(&tusb320_extcon_driver);
+}
+module_exit(tusb320_exit);
+
+MODULE_AUTHOR("Michael Auchter <michael.auchter@ni.com>");
+MODULE_DESCRIPTION("TI TUSB320 extcon driver");
+MODULE_LICENSE("GPL v2");
-- 
2.25.4