linux-kernel - Re: [PATCH 2/2] extcon: usbc-tusb320: add usb_role

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Date:   Fri, 17 Mar 2023 13:13:51 +0200
From:   Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To:     Alvin Šipraga <alvin@...s.dk>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        linux-usb@...r.kernel.org,
        Alvin Šipraga <alsi@...g-olufsen.dk>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] extcon: usbc-tusb320: add usb_role_switch support

On Fri, Mar 17, 2023 at 11:42:28AM +0100, Alvin Šipraga wrote:
> From: Alvin Šipraga <alsi@...g-olufsen.dk>
> 
> The connector child node of the TUSB320 device might be linked with a
> USB OTG controller with USB role switch capability. Add driver support
> for detecting a usb_role_switch and setting its state in the typec
> interrupt handler. This follows similar practice in other drivers in the
> typec subsystem, which this extcon driver can opt-in to.

I'm sorry to be a bit picky here, but I must ask that you don't use
the term USB OTG. It is too confusing - OTG may refer to USB device
controller, USB host controller, or dual-role capable USB controller,
depending on the case, so we need to be specific.

The OTG spec itself is in any case obsolete - USB Type-C and USB PD
specs define their own way of handling the roles, and they are not
compatible with the USB OTG specification(s).

thanks,

> Signed-off-by: Alvin Šipraga <alsi@...g-olufsen.dk>
> ---
> v2: remove unused variable as reported by kernel test robot
> ---
>  drivers/extcon/extcon-usbc-tusb320.c | 21 +++++++++++++++++++++
>  1 file changed, 21 insertions(+)
> 
> diff --git a/drivers/extcon/extcon-usbc-tusb320.c b/drivers/extcon/extcon-usbc-tusb320.c
> index 882d1f48495e..cc2d0ac7c5f6 100644
> --- a/drivers/extcon/extcon-usbc-tusb320.c
> +++ b/drivers/extcon/extcon-usbc-tusb320.c
> @@ -16,6 +16,7 @@
>  #include <linux/regmap.h>
>  #include <linux/usb/typec.h>
>  #include <linux/usb/typec_altmode.h>
> +#include <linux/usb/role.h>
>  
>  #define TUSB320_REG8				0x8
>  #define TUSB320_REG8_CURRENT_MODE_ADVERTISE	GENMASK(7, 6)
> @@ -80,6 +81,7 @@ struct tusb320_priv {
>  	enum typec_port_type port_type;
>  	enum typec_pwr_opmode pwr_opmode;
>  	struct fwnode_handle *connector_fwnode;
> +	struct usb_role_switch *role_sw;
>  };
>  
>  static const char * const tusb_attached_states[] = {
> @@ -278,6 +280,7 @@ static void tusb320_typec_irq_handler(struct tusb320_priv *priv, u8 reg9)
>  	struct typec_port *port = priv->port;
>  	struct device *dev = priv->dev;
>  	int typec_mode;
> +	enum usb_role usb_role;
>  	enum typec_role pwr_role;
>  	enum typec_data_role data_role;
>  	u8 state, mode, accessory;
> @@ -300,11 +303,13 @@ static void tusb320_typec_irq_handler(struct tusb320_priv *priv, u8 reg9)
>  	switch (state) {
>  	case TUSB320_ATTACHED_STATE_DFP:
>  		typec_mode = TYPEC_MODE_USB2;
> +		usb_role = USB_ROLE_HOST;
>  		pwr_role = TYPEC_SOURCE;
>  		data_role = TYPEC_HOST;
>  		break;
>  	case TUSB320_ATTACHED_STATE_UFP:
>  		typec_mode = TYPEC_MODE_USB2;
> +		usb_role = USB_ROLE_DEVICE;
>  		pwr_role = TYPEC_SINK;
>  		data_role = TYPEC_DEVICE;
>  		break;
> @@ -316,6 +321,7 @@ static void tusb320_typec_irq_handler(struct tusb320_priv *priv, u8 reg9)
>  		if (accessory == TUSB320_REG8_ACCESSORY_CONNECTED_AUDIO ||
>  		    accessory == TUSB320_REG8_ACCESSORY_CONNECTED_ACHRG) {
>  			typec_mode = TYPEC_MODE_AUDIO;
> +			usb_role = USB_ROLE_NONE;
>  			pwr_role = TYPEC_SINK;
>  			data_role = TYPEC_DEVICE;
>  			break;
> @@ -323,12 +329,14 @@ static void tusb320_typec_irq_handler(struct tusb320_priv *priv, u8 reg9)
>  			   TUSB320_REG8_ACCESSORY_CONNECTED_DBGDFP) {
>  			typec_mode = TYPEC_MODE_DEBUG;
>  			pwr_role = TYPEC_SOURCE;
> +			usb_role = USB_ROLE_HOST;
>  			data_role = TYPEC_HOST;
>  			break;
>  		} else if (accessory ==
>  			   TUSB320_REG8_ACCESSORY_CONNECTED_DBGUFP) {
>  			typec_mode = TYPEC_MODE_DEBUG;
>  			pwr_role = TYPEC_SINK;
> +			usb_role = USB_ROLE_DEVICE;
>  			data_role = TYPEC_DEVICE;
>  			break;
>  		}
> @@ -339,6 +347,7 @@ static void tusb320_typec_irq_handler(struct tusb320_priv *priv, u8 reg9)
>  		fallthrough;
>  	default:
>  		typec_mode = TYPEC_MODE_USB2;
> +		usb_role = USB_ROLE_NONE;
>  		pwr_role = TYPEC_SINK;
>  		data_role = TYPEC_DEVICE;
>  		break;
> @@ -348,6 +357,7 @@ static void tusb320_typec_irq_handler(struct tusb320_priv *priv, u8 reg9)
>  	typec_set_pwr_role(port, pwr_role);
>  	typec_set_data_role(port, data_role);
>  	typec_set_mode(port, typec_mode);
> +	usb_role_switch_set_role(priv->role_sw, usb_role);
>  
>  	mode = FIELD_GET(TUSB320_REG8_CURRENT_MODE_DETECT, reg8);
>  	if (mode == TUSB320_REG8_CURRENT_MODE_DETECT_DEF)
> @@ -472,10 +482,20 @@ static int tusb320_typec_probe(struct i2c_client *client,
>  		goto err_put;
>  	}
>  
> +	/* Find any optional USB role switch that needs reporting to */
> +	priv->role_sw = fwnode_usb_role_switch_get(connector);
> +	if (IS_ERR(priv->role_sw)) {
> +		ret = PTR_ERR(priv->role_sw);
> +		goto err_unreg;
> +	}
> +
>  	priv->connector_fwnode = connector;
>  
>  	return 0;
>  
> +err_unreg:
> +	typec_unregister_port(priv->port);
> +
>  err_put:
>  	fwnode_handle_put(connector);
>  
> @@ -484,6 +504,7 @@ static int tusb320_typec_probe(struct i2c_client *client,
>  
>  static void tusb320_typec_remove(struct tusb320_priv *priv)
>  {
> +	usb_role_switch_put(priv->role_sw);
>  	typec_unregister_port(priv->port);
>  	fwnode_handle_put(priv->connector_fwnode);
>  }
> -- 
> 2.39.2

-- 
heikki