linux-kernel - Re: [PATCH v2 2/2] usb: typec: tcpci_maxim: configure charging & data paths

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Date:   Thu, 11 Mar 2021 22:39:29 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Badhri Jagan Sridharan <badhri@...gle.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Kyle Tso <kyletso@...gle.com>
Subject: Re: [PATCH v2 2/2] usb: typec: tcpci_maxim: configure charging & data
 paths

On 3/11/21 9:24 PM, Badhri Jagan Sridharan wrote:
> The change exposes the data_role and the orientation as a extcon
> interface for configuring the USB data controller.
> 
> Signed-off-by: Badhri Jagan Sridharan <badhri@...gle.com>
> ---
> Changes since V1:
> - Dropped changes related to get_/set_current_limit and pd_capable
>   callback. Will send them in as separate patches.
> ---
>  drivers/usb/typec/tcpm/tcpci_maxim.c | 56 ++++++++++++++++++++++++++++
>  1 file changed, 56 insertions(+)
> 
> diff --git a/drivers/usb/typec/tcpm/tcpci_maxim.c b/drivers/usb/typec/tcpm/tcpci_maxim.c
> index 041a1c393594..1210445713ee 100644
> --- a/drivers/usb/typec/tcpm/tcpci_maxim.c
> +++ b/drivers/usb/typec/tcpm/tcpci_maxim.c
> @@ -7,6 +7,8 @@
>  
>  #include <linux/interrupt.h>
>  #include <linux/i2c.h>
> +#include <linux/extcon.h>
> +#include <linux/extcon-provider.h>
>  #include <linux/kernel.h>
>  #include <linux/module.h>
>  #include <linux/regmap.h>
> @@ -46,6 +48,8 @@ struct max_tcpci_chip {
>  	struct device *dev;
>  	struct i2c_client *client;
>  	struct tcpm_port *port;
> +	bool attached;
> +	struct extcon_dev *extcon;
>  };
>  
>  static const struct regmap_range max_tcpci_tcpci_range[] = {
> @@ -439,6 +443,39 @@ static int tcpci_init(struct tcpci *tcpci, struct tcpci_data *data)
>  	return -1;
>  }
>  
> +static void max_tcpci_set_roles(struct tcpci *tcpci, struct tcpci_data *data, bool attached,
> +				enum typec_role role, enum typec_data_role data_role)
> +{
> +	struct max_tcpci_chip *chip = tdata_to_max_tcpci(data);
> +
> +	chip->attached = attached;
> +
> +	if (!attached) {
> +		extcon_set_state_sync(chip->extcon, EXTCON_USB_HOST, 0);
> +		extcon_set_state_sync(chip->extcon, EXTCON_USB, 0);
> +		return;
> +	}
> +
> +	extcon_set_state_sync(chip->extcon, data_role == TYPEC_HOST ? EXTCON_USB_HOST : EXTCON_USB,
> +			      1);
> +}
> +
> +static void max_tcpci_set_cc_polarity(struct tcpci *tcpci, struct tcpci_data *data,
> +				      enum typec_cc_polarity polarity)
> +{
> +	struct max_tcpci_chip *chip = tdata_to_max_tcpci(data);
> +
> +	extcon_set_property(chip->extcon, EXTCON_USB, EXTCON_PROP_USB_TYPEC_POLARITY,
> +			    (union extcon_property_value)(int)polarity);
> +	extcon_set_property(chip->extcon, EXTCON_USB_HOST, EXTCON_PROP_USB_TYPEC_POLARITY,
> +			    (union extcon_property_value)(int)polarity);
> +}
> +
> +static const unsigned int usbpd_extcon[] = {
> +	EXTCON_USB,
> +	EXTCON_USB_HOST,
> +};
> +
>  static int max_tcpci_probe(struct i2c_client *client, const struct i2c_device_id *i2c_id)
>  {
>  	int ret;
> @@ -472,6 +509,8 @@ static int max_tcpci_probe(struct i2c_client *client, const struct i2c_device_id
>  	chip->data.auto_discharge_disconnect = true;
>  	chip->data.vbus_vsafe0v = true;
>  	chip->data.set_partner_usb_comm_capable = max_tcpci_set_partner_usb_comm_capable;
> +	chip->data.set_roles = max_tcpci_set_roles;
> +	chip->data.set_cc_polarity = max_tcpci_set_cc_polarity;
>  
>  	max_tcpci_init_regs(chip);
>  	chip->tcpci = tcpci_register_port(chip->dev, &chip->data);
> @@ -484,6 +523,23 @@ static int max_tcpci_probe(struct i2c_client *client, const struct i2c_device_id
>  	if (ret < 0)
>  		goto unreg_port;
>  
> +	chip->extcon = devm_extcon_dev_allocate(&client->dev, usbpd_extcon);
> +	if (IS_ERR(chip->extcon)) {
> +		dev_err(&client->dev, "Error allocating extcon: %ld\n", PTR_ERR(chip->extcon));
> +		ret = PTR_ERR(chip->extcon);
> +		goto unreg_port;
> +	}
> +
> +	ret = devm_extcon_dev_register(&client->dev, chip->extcon);
> +	if (ret < 0) {
> +		dev_err(&client->dev, "failed to register extcon device");
> +		goto unreg_port;
> +	}

Effectively this mandates extcon support to be able to use this driver/chip.
Does that make sense ? If this is indeed mandatory, how did it work so far ?

Also, what makes this code chip specific ?

Thanks,
Guenter

> +
> +	extcon_set_property_capability(chip->extcon, EXTCON_USB, EXTCON_PROP_USB_TYPEC_POLARITY);
> +	extcon_set_property_capability(chip->extcon, EXTCON_USB_HOST,
> +				       EXTCON_PROP_USB_TYPEC_POLARITY);
> +
>  	device_init_wakeup(chip->dev, true);
>  	return 0;
>  
>