Re: [PATCH v4 2/2] usb: typec: tcpm: Add support for Battery Status response message

[Heikki Krogerus <heikki.krogerus@linux.intel.com>]

On Wed, Jul 01, 2026 at 02:49:08PM -0700, Amit Sunil Dhamne wrote:
> 
> On 6/30/26 5:34 PM, Amit Sunil Dhamne via B4 Relay wrote:
> > From: Amit Sunil Dhamne <amitsd@google.com>
> > 
> > Add support for responding to a Get_Battery_Status request with a
> > Battery_Status message. The port partner shall request the status of a
> > port's battery by providing an index in the Get_Battery_Status AMS. In
> > case of failure to identify the battery, the port shall reply with an
> > appropriate message indicating so.
> > 
> > Support for Battery_Status message is required for sinks that contain
> > battery as specified in USB PD Rev3.1 v1.8
> > ("Applicability of Data Messages" section).
> > 
> > Signed-off-by: Amit Sunil Dhamne <amitsd@google.com>
> > Reviewed-by: Badhri Jagan Sridharan <badhri@google.com>
> 
> Unfortunately, I forgot to add Heikki's ack [1] . In case I have to send a
> new revision and this tcpm patch looks okay, I will add the Ack.

No worries:

Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
 
> [1] https://lore.kernel.org/all/aiLHSlkdw_BAO6c_@kuha/
> 
> 
> Thanks,
> 
> Amit
> 
> > ---
> >   drivers/usb/typec/tcpm/tcpm.c | 135 +++++++++++++++++++++++++++++++++++++++++-
> >   include/linux/usb/pd.h        |  29 +++++++++
> >   2 files changed, 161 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
> > index 7ef746a90a17..19daa17917a7 100644
> > --- a/drivers/usb/typec/tcpm/tcpm.c
> > +++ b/drivers/usb/typec/tcpm/tcpm.c
> > @@ -232,7 +232,8 @@ enum pd_msg_request {
> >   	PD_MSG_DATA_SINK_CAP,
> >   	PD_MSG_DATA_SOURCE_CAP,
> >   	PD_MSG_DATA_REV,
> > -	PD_MSG_EXT_SINK_CAP_EXT
> > +	PD_MSG_EXT_SINK_CAP_EXT,
> > +	PD_MSG_DATA_BATT_STATUS
> >   };
> >   enum adev_actions {
> > @@ -389,6 +390,14 @@ struct pd_timings {
> >   /* Convert microwatt to watt */
> >   #define UW_TO_W(pow)					((pow) / 1000000)
> > +/*
> > + * As per USB PD Spec Rev 3.18 (Sec. 6.5.13.11), the number of fixed batteries
> > + * that a port can be queried is restricted to 4.
> > + */
> > +#define MAX_NUM_FIXED_BATT				4
> > +
> > +#define BATTERY_PROPERTY_UNKNOWN			0xffff
> > +
> >   /*
> >    * struct pd_identifier - Contains info about PD identifiers
> >    * @vid: Vendor ID (assigned by USB-IF)
> > @@ -683,6 +692,9 @@ struct tcpm_port {
> >   	struct pd_identifier pd_ident;
> >   	struct sink_caps_ext_data sink_caps_ext;
> > +	struct power_supply **fixed_batt;
> > +	u32 fixed_batt_cnt;
> > +	u32 batt_request_id;
> >   #ifdef CONFIG_DEBUG_FS
> >   	struct dentry *dentry;
> >   	struct mutex logbuffer_lock;	/* log buffer access lock */
> > @@ -1470,6 +1482,20 @@ static int tcpm_pd_send_sink_caps(struct tcpm_port *port)
> >   	return tcpm_pd_transmit(port, TCPC_TX_SOP, &msg);
> >   }
> > +static void tcpm_get_fixed_batt(struct tcpm_port *port)
> > +{
> > +	int ret;
> > +
> > +	if (!port->self_powered || port->fixed_batt_cnt > 0)
> > +		return;
> > +
> > +	ret = power_supply_get_system_batteries(port->dev, &port->fixed_batt);
> > +	if (ret < 0)
> > +		tcpm_log(port, "Failed to get battery array, ret=%d", ret);
> > +	else
> > +		port->fixed_batt_cnt = ret;
> > +}
> > +
> >   static int tcpm_pd_send_sink_cap_ext(struct tcpm_port *port)
> >   {
> >   	u16 operating_snk_watt = port->operating_snk_mw / 1000;
> > @@ -1482,6 +1508,8 @@ static int tcpm_pd_send_sink_cap_ext(struct tcpm_port *port)
> >   	if (!port->self_powered)
> >   		data->spr_op_pdp = operating_snk_watt;
> > +	tcpm_get_fixed_batt(port);
> > +
> >   	/*
> >   	 * SPR Sink Minimum PDP indicates the minimum power required to operate
> >   	 * a sink device in its lowest level of functionality without requiring
> > @@ -1507,6 +1535,7 @@ static int tcpm_pd_send_sink_cap_ext(struct tcpm_port *port)
> >   	skedb.load_step = data->load_step;
> >   	skedb.load_char = cpu_to_le16(data->load_char);
> >   	skedb.compliance = data->compliance;
> > +	skedb.batt_info = min(port->fixed_batt_cnt, MAX_NUM_FIXED_BATT);
> >   	skedb.modes = data->modes;
> >   	skedb.spr_min_pdp = data->spr_min_pdp;
> >   	skedb.spr_op_pdp = data->spr_op_pdp;
> > @@ -1525,6 +1554,88 @@ static int tcpm_pd_send_sink_cap_ext(struct tcpm_port *port)
> >   					   port->message_id,
> >   					   data_obj_cnt,
> >   					   1 /* Denotes if ext header */));
> > +
> > +	return tcpm_pd_transmit(port, TCPC_TX_SOP, &msg);
> > +}
> > +
> > +static int tcpm_pd_send_batt_status(struct tcpm_port *port)
> > +{
> > +	u16 present_charge = BATTERY_PROPERTY_UNKNOWN;
> > +	bool batt_present = false, invalid_ref = true;
> > +	u32 batt_id = port->batt_request_id;
> > +	union power_supply_propval val;
> > +	struct power_supply *batt;
> > +	u8 charging_status = 0;
> > +	struct pd_message msg;
> > +	int ret, charge_now;
> > +	u64 energy_now;
> > +	u32 bsdo;
> > +
> > +	tcpm_get_fixed_batt(port);
> > +	memset(&msg, 0, sizeof(msg));
> > +
> > +	if (batt_id >= port->fixed_batt_cnt || batt_id >= MAX_NUM_FIXED_BATT)
> > +		goto send_status;
> > +
> > +	invalid_ref = false;
> > +	batt = port->fixed_batt[batt_id];
> > +	ret = power_supply_get_property(batt, POWER_SUPPLY_PROP_PRESENT, &val);
> > +	if (ret)
> > +		tcpm_log(port,
> > +			 "Failed to fetch power_supply_prop_present ret %d",
> > +			 ret);
> > +	else
> > +		batt_present = val.intval > 0;
> > +
> > +	ret = power_supply_get_property(batt, POWER_SUPPLY_PROP_CHARGE_NOW,
> > +					&val);
> > +	if (!ret) {
> > +		charge_now = val.intval;
> > +
> > +		ret = power_supply_get_property(batt,
> > +						POWER_SUPPLY_PROP_VOLTAGE_AVG,
> > +						&val);
> > +		if (!ret) {
> > +			energy_now = ((u64)charge_now * val.intval) / 1000000;
> > +
> > +			/*
> > +			 * Battery Present Charge is reported in
> > +			 * increments of 0.1WH.
> > +			 */
> > +			present_charge = (u16)UW_TO_W(energy_now * 10);
> > +		}
> > +	}
> > +
> > +	ret = power_supply_get_property(batt, POWER_SUPPLY_PROP_STATUS, &val);
> > +	if (!ret) {
> > +		switch (val.intval) {
> > +		case POWER_SUPPLY_STATUS_CHARGING:
> > +			charging_status = BSDO_BATTERY_INFO_CHARGING;
> > +			break;
> > +		case POWER_SUPPLY_STATUS_DISCHARGING:
> > +			charging_status = BSDO_BATTERY_INFO_DISCHARGING;
> > +			break;
> > +		case POWER_SUPPLY_STATUS_NOT_CHARGING:
> > +		case POWER_SUPPLY_STATUS_FULL:
> > +			charging_status = BSDO_BATTERY_INFO_IDLE;
> > +			break;
> > +		default:
> > +			charging_status = BSDO_BATTERY_INFO_RSVD;
> > +			break;
> > +		}
> > +	}
> > +
> > +send_status:
> > +
> > +	bsdo = BSDO(present_charge, charging_status, batt_present, invalid_ref);
> > +	msg.payload[0] = cpu_to_le32(bsdo);
> > +	msg.header = PD_HEADER_LE(PD_DATA_BATT_STATUS,
> > +				  port->pwr_role,
> > +				  port->data_role,
> > +				  port->negotiated_rev,
> > +				  port->message_id,
> > +				  1);
> > +
> >   	return tcpm_pd_transmit(port, TCPC_TX_SOP, &msg);
> >   }
> > @@ -3886,6 +3997,7 @@ static void tcpm_pd_ext_msg_request(struct tcpm_port *port,
> >   {
> >   	enum pd_ext_msg_type type = pd_header_type_le(msg->header);
> >   	unsigned int data_size = pd_ext_header_data_size_le(msg->ext_msg.header);
> > +	const struct pd_chunked_ext_message_data *ext_msg = &msg->ext_msg;
> >   	/* stopping VDM state machine if interrupted by other Messages */
> >   	if (tcpm_vdm_ams(port)) {
> > @@ -3894,7 +4006,7 @@ static void tcpm_pd_ext_msg_request(struct tcpm_port *port,
> >   		mod_vdm_delayed_work(port, 0);
> >   	}
> > -	if (!(le16_to_cpu(msg->ext_msg.header) & PD_EXT_HDR_CHUNKED)) {
> > +	if (!(le16_to_cpu(ext_msg->header) & PD_EXT_HDR_CHUNKED)) {
> >   		tcpm_pd_handle_msg(port, PD_MSG_CTRL_NOT_SUPP, NONE_AMS);
> >   		tcpm_log(port, "Unchunked extended messages unsupported");
> >   		return;
> > @@ -3919,9 +4031,17 @@ static void tcpm_pd_ext_msg_request(struct tcpm_port *port,
> >   					     NONE_AMS, 0);
> >   		}
> >   		break;
> > +	case PD_EXT_GET_BATT_STATUS:
> > +		if (data_size >= 1) {
> > +			port->batt_request_id = ext_msg->data[0];
> > +			tcpm_pd_handle_msg(port, PD_MSG_DATA_BATT_STATUS,
> > +					   GETTING_BATTERY_STATUS);
> > +		} else {
> > +			tcpm_set_state(port, SOFT_RESET_SEND, 0);
> > +		}
> > +		break;
> >   	case PD_EXT_SOURCE_CAP_EXT:
> >   	case PD_EXT_GET_BATT_CAP:
> > -	case PD_EXT_GET_BATT_STATUS:
> >   	case PD_EXT_BATT_CAP:
> >   	case PD_EXT_GET_MANUFACTURER_INFO:
> >   	case PD_EXT_MANUFACTURER_INFO:
> > @@ -4132,6 +4252,14 @@ static bool tcpm_send_queued_message(struct tcpm_port *port)
> >   					 ret);
> >   			tcpm_ams_finish(port);
> >   			break;
> > +		case PD_MSG_DATA_BATT_STATUS:
> > +			ret = tcpm_pd_send_batt_status(port);
> > +			if (ret)
> > +				tcpm_log(port,
> > +					 "Failed to send battery status ret=%d",
> > +					 ret);
> > +			tcpm_ams_finish(port);
> > +			break;
> >   		default:
> >   			break;
> >   		}
> > @@ -8633,6 +8761,7 @@ void tcpm_unregister_port(struct tcpm_port *port)
> >   	hrtimer_cancel(&port->vdm_state_machine_timer);
> >   	hrtimer_cancel(&port->state_machine_timer);
> > +	power_supply_put_system_batteries(port->fixed_batt, port->fixed_batt_cnt);
> >   	tcpm_reset_port(port);
> >   	tcpm_port_unregister_pd(port);
> > diff --git a/include/linux/usb/pd.h b/include/linux/usb/pd.h
> > index 337a5485af7c..afb9c2c65588 100644
> > --- a/include/linux/usb/pd.h
> > +++ b/include/linux/usb/pd.h
> > @@ -724,4 +724,33 @@ void usb_power_delivery_unlink_device(struct usb_power_delivery *pd, struct devi
> >   #endif /* CONFIG_TYPEC */
> > +/* Battery Status Data Object */
> > +#define BSDO_PRESENT_CAPACITY				GENMASK(31, 16)
> > +#define BSDO_CHG_STATUS					GENMASK(11, 10)
> > +#define BSDO_BATTERY_PRESENT				BIT(9)
> > +#define BSDO_INVALID_BATTERY_REFERENCE			BIT(8)
> > +
> > +/*
> > + * Battery Charge Status: Battery Charging Status Values as defined in
> > + * "USB PD Spec Rev3.1 Ver1.8", "Table 6-46 Battery Status Data Object (BSDO)".
> > + */
> > +#define BSDO_BATTERY_INFO_CHARGING			0x0
> > +#define BSDO_BATTERY_INFO_DISCHARGING			0x1
> > +#define BSDO_BATTERY_INFO_IDLE				0x2
> > +#define BSDO_BATTERY_INFO_RSVD				0x3
> > +
> > +/**
> > + * BSDO() - Pack data into Battery Status Data Object format.
> > + * @batt_charge: Battery's present state of charge in 0.1WH increment.
> > + * @chg_status: Battery charge status.
> > + * @batt_present: Indicates that battery is present/attached when set else absent when unset.
> > + * @invalid_ref: Indicates that an invalid battery reference was made in the Get_Battery_Status
> > + *		 request.
> > + */
> > +#define BSDO(batt_charge, chg_status, batt_present, invalid_ref)	\
> > +	((FIELD_PREP(BSDO_PRESENT_CAPACITY, batt_charge)) |		\
> > +	 (FIELD_PREP(BSDO_CHG_STATUS, chg_status)) |			\
> > +	 ((batt_present) ? BSDO_BATTERY_PRESENT : 0) |			\
> > +	 ((invalid_ref) ? BSDO_INVALID_BATTERY_REFERENCE : 0))
> > +
> >   #endif /* __LINUX_USB_PD_H */
> > 

-- 
heikki