Re: [PATCH v2 2/3] usb: typec: tcpci: implement get_current_limit

[Heikki Krogerus]

On Sun, Oct 04, 2026 at 03:41:00AM +0000, Amit Sunil Dhamne via B4 Relay wrote:
> From: Amit Sunil Dhamne <amitsd@xxxxxxxxxx>
> 
> Implement a callback for tcpc_dev::get_current_limit. This acts like a
> conduit to relay the current limit information from chip level tcpc
> drivers.
> 
> This does not introduce any functional changes for chip level drivers
> that do not implement tcpci_data::get_current_limit.
> 
> Assisted-by: LLM
> Signed-off-by: Amit Sunil Dhamne <amitsd@xxxxxxxxxx>
> Reviewed-by: Badhri Jagan Sridharan <badhri@xxxxxxxxxx>

Acked-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>

> ---
>  drivers/usb/typec/tcpm/tcpci.c | 14 ++++++++++++++
>  include/linux/usb/tcpci.h      |  6 ++++++
>  2 files changed, 20 insertions(+)
> 
> diff --git a/drivers/usb/typec/tcpm/tcpci.c b/drivers/usb/typec/tcpm/tcpci.c
> index 6717ac914c6a..f1bc1ac0a556 100644
> --- a/drivers/usb/typec/tcpm/tcpci.c
> +++ b/drivers/usb/typec/tcpm/tcpci.c
> @@ -250,6 +250,19 @@ static int tcpci_get_cc(struct tcpc_dev *tcpc,
>  	return 0;
>  }
>  
> +static int tcpci_get_current_limit(struct tcpc_dev *tcpc)
> +{
> +	struct tcpci *tcpci = tcpc_to_tcpci(tcpc);
> +	int ret;
> +
> +	if (!tcpci->data->get_current_limit)
> +		return 0;
> +
> +	ret = tcpci->data->get_current_limit(tcpci, tcpci->data);
> +
> +	return ret < 0 ? 0 : ret;
> +}
> +
>  static int tcpci_set_polarity(struct tcpc_dev *tcpc,
>  			      enum typec_cc_polarity polarity)
>  {
> @@ -861,6 +874,7 @@ struct tcpci *tcpci_register_port(struct device *dev, struct tcpci_data *data)
>  	tcpci->tcpc.set_cc = tcpci_set_cc;
>  	tcpci->tcpc.apply_rc = tcpci_apply_rc;
>  	tcpci->tcpc.get_cc = tcpci_get_cc;
> +	tcpci->tcpc.get_current_limit = tcpci_get_current_limit;
>  	tcpci->tcpc.set_polarity = tcpci_set_polarity;
>  	tcpci->tcpc.set_vconn = tcpci_set_vconn;
>  	tcpci->tcpc.start_toggling = tcpci_start_toggling;
> diff --git a/include/linux/usb/tcpci.h b/include/linux/usb/tcpci.h
> index 9b46a6bc762c..580fbdac7ede 100644
> --- a/include/linux/usb/tcpci.h
> +++ b/include/linux/usb/tcpci.h
> @@ -205,6 +205,11 @@ struct tcpci;
>   *		swap following Discover Identity on SOP' occurs.
>   *		Return true when the TCPM is allowed to request a Vconn swap
>   *		after Discovery Identity on SOP.
> + * @get_current_limit:
> + *		Optional; Called when the port is a sink and CC=Rp-def to obtain
> + *		the current limit. Chip level drivers can implement their own
> + *		detection and return the limit in mA, or 0 when it cannot be
> + *		determined.
>   * @set_orientation:
>   *		Optional; Enable setting the connector orientation
>   *		CONFIG_STANDARD_OUTPUT (0x18) bit0.
> @@ -228,6 +233,7 @@ struct tcpci_data {
>  					     bool capable);
>  	void (*check_contaminant)(struct tcpci *tcpci, struct tcpci_data *data);
>  	bool (*attempt_vconn_swap_discovery)(struct tcpci *tcpci, struct tcpci_data *data);
> +	int (*get_current_limit)(struct tcpci *tcpci, struct tcpci_data *data);
>  };
>  
>  struct tcpci *tcpci_register_port(struct device *dev, struct tcpci_data *data);
> 
> -- 
> 2.56.0.rc1.315.gc6ed9934b7-goog
> 

-- 
heikki