Re: [PATCH 1/2] extcon: add driver for TI TUSB320

[Chanwoo Choi]

Hi,

Almost looks good to me. I added some comments.

On 10/9/20 7:39 AM, Michael Auchter wrote:
> 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@xxxxxx>
> ---
>  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@xxxxxx>
> + *
> + * 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.

You don't need to additional license info below 'author'
because you added '// SPDX-License-Identifier: GPL-2.0' at the first line.

> + */
> +
> +#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)

You need to define what is meaning of '6' and '0x3'.

#define TUSB30_xxx_SHIFT	6
#define TUSB30_xxx_MASK		0x3

> +#define TUSB320_REG_9_GET_CABLE_DIR(reg) (((reg) >> 5) & 1)

ditto.

#define TUSB30_xxx__SHIFT	5
#define TUSB30_xxx_MASK		0x1


> +#define TUSB320_ATTACHED_STATE_NONE 0x0
> +#define TUSB320_ATTACHED_STATE_DFP  0x1
> +#define TUSB320_ATTACHED_STATE_UFP  0x2
> +#define TUSB320_ATTACHED_STATE_ACC  0x3
> +

nitpick. For the indentation, how about editing as following:

#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;

I recommend that you better to use regmap_i2c with devm_regmap_init_i2c() function
instead of using i2c_smbus_*() function. You can refer regmap_i2c usage
on drivers/extcon/extcon-sm5502.c.

> +
> +	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@xxxxxx>");
> +MODULE_DESCRIPTION("TI TUSB320 extcon driver");
> +MODULE_LICENSE("GPL v2");
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics