[PATCH] usb: typec: tcpm: Add support for Battery Cap response message
From: Amit Sunil Dhamne via B4 Relay
Date: Tue Jul 14 2026 - 19:09:46 EST
From: Amit Sunil Dhamne <amitsd@xxxxxxxxxx>
Add support for responding to Get_Battery_Cap (extended) request with a
a Battery_Capabilities (extended) msg. The requester will request
Battery Cap for a specific battery using an index in Get_Battery_Cap. In
case of failure to identify battery, TCPM shall reply with an
appropriate message indicating so.
As the Battery Cap Data Block size is 9 Bytes (lesser than
MaxExtendedMsgChunkLen of 26B), only a single chunk is required to
complete the AMS.
Support for Battery_Capabilities 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@xxxxxxxxxx>
Reviewed-by: Badhri Jagan Sridharan <badhri@xxxxxxxxxx>
---
This patch depends on the series [1].
[1] https://lore.kernel.org/all/20260714-batt-status-v5-0-9de4aa900b69@xxxxxxxxxx/
---
drivers/usb/typec/tcpm/tcpm.c | 108 +++++++++++++++++++++++++++++++++++++-----
include/linux/usb/pd.h | 22 +++++++++
2 files changed, 117 insertions(+), 13 deletions(-)
diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
index cd33ee131ebd..393266dd55f8 100644
--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -234,7 +234,8 @@ enum pd_msg_request {
PD_MSG_DATA_SOURCE_CAP,
PD_MSG_DATA_REV,
PD_MSG_EXT_SINK_CAP_EXT,
- PD_MSG_DATA_BATT_STATUS
+ PD_MSG_DATA_BATT_STATUS,
+ PD_MSG_EXT_BATT_CAP,
};
enum adev_actions {
@@ -1559,6 +1560,14 @@ static int tcpm_pd_send_sink_cap_ext(struct tcpm_port *port)
return tcpm_pd_transmit(port, TCPC_TX_SOP, &msg);
}
+static u16 tcpm_charge_to_energy(int charge, int voltage)
+{
+ u64 energy = div_u64((u64)charge * voltage, 1000000);
+
+ /* Battery telemetry is reported in increments of 0.1Wh */
+ return (u16)UW_TO_W(energy * 10);
+}
+
static int tcpm_pd_send_batt_status(struct tcpm_port *port)
{
u16 present_charge = BATTERY_PROPERTY_UNKNOWN;
@@ -1569,7 +1578,6 @@ static int tcpm_pd_send_batt_status(struct tcpm_port *port)
u8 charging_status = 0;
struct pd_message msg;
int ret, charge_now;
- u64 energy_now;
u32 bsdo;
tcpm_get_fixed_batt(port);
@@ -1595,16 +1603,9 @@ static int tcpm_pd_send_batt_status(struct tcpm_port *port)
ret = power_supply_get_property(batt,
POWER_SUPPLY_PROP_VOLTAGE_AVG,
&val);
- if (!ret) {
- energy_now = div_u64((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);
- }
+ if (!ret)
+ present_charge = tcpm_charge_to_energy(charge_now,
+ val.intval);
}
ret = power_supply_get_property(batt, POWER_SUPPLY_PROP_STATUS, &val);
@@ -1640,6 +1641,71 @@ static int tcpm_pd_send_batt_status(struct tcpm_port *port)
return tcpm_pd_transmit(port, TCPC_TX_SOP, &msg);
}
+static int tcpm_pd_send_batt_cap(struct tcpm_port *port)
+{
+ u16 design_cap = BATTERY_PROPERTY_UNKNOWN;
+ u16 charge_cap = BATTERY_PROPERTY_UNKNOWN;
+ u32 batt_id = port->batt_request_id;
+ union power_supply_propval val;
+ struct batt_cap_ext_msg bcdb;
+ struct power_supply *batt;
+ bool invalid_ref = true;
+ struct pd_message msg;
+ u8 data_obj_cnt;
+ int ret, vol;
+
+ 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_cap;
+
+ invalid_ref = false;
+ batt = port->fixed_batt[batt_id];
+ ret = power_supply_get_property(batt, POWER_SUPPLY_PROP_VOLTAGE_AVG,
+ &val);
+ if (!ret) {
+ vol = val.intval;
+ ret = power_supply_get_property(batt,
+ POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN,
+ &val);
+ if (!ret)
+ design_cap = tcpm_charge_to_energy(val.intval, vol);
+
+ ret = power_supply_get_property(batt,
+ POWER_SUPPLY_PROP_CHARGE_FULL,
+ &val);
+ if (!ret)
+ charge_cap = tcpm_charge_to_energy(val.intval, vol);
+ }
+
+send_cap:
+
+ /*
+ * As per the USB PD Rev3.1 v1.8 spec, if a battery VID (assigned by the
+ * USB-IF) does not exist or an invalid battery reference is made by the
+ * requestor, then set the VID field to 0xffff. If the VID field is
+ * 0xffff, set the PID field to 0.
+ */
+ bcdb.vid = BATTERY_PROPERTY_UNKNOWN;
+ bcdb.pid = 0;
+ bcdb.batt_design_cap = cpu_to_le16(design_cap);
+ bcdb.batt_last_chg_cap = cpu_to_le16(charge_cap);
+ bcdb.batt_type = invalid_ref ? BATT_CAP_BATT_TYPE_INVALID_REF : 0;
+ memcpy(msg.ext_msg.data, &bcdb, sizeof(bcdb));
+ msg.ext_msg.header = PD_EXT_HDR_LE(sizeof(bcdb),
+ 0, /* Denotes if request chunk */
+ 0, /* Chunk number */
+ 1 /* Chunked */);
+
+ data_obj_cnt = count_chunked_data_objs(sizeof(bcdb));
+ msg.header = PD_HEADER_EXT_LE(PD_EXT_BATT_CAP, port->pwr_role,
+ port->data_role, port->negotiated_rev,
+ port->message_id, data_obj_cnt);
+
+ return tcpm_pd_transmit(port, TCPC_TX_SOP, &msg);
+}
+
static void mod_tcpm_delayed_work(struct tcpm_port *port, unsigned int delay_ms)
{
if (delay_ms) {
@@ -4041,8 +4107,16 @@ static void tcpm_pd_ext_msg_request(struct tcpm_port *port,
tcpm_set_state(port, SOFT_RESET_SEND, 0);
}
break;
- case PD_EXT_SOURCE_CAP_EXT:
case PD_EXT_GET_BATT_CAP:
+ if (data_size >= 1) {
+ port->batt_request_id = ext_msg->data[0];
+ tcpm_pd_handle_msg(port, PD_MSG_EXT_BATT_CAP,
+ GETTING_BATTERY_CAPABILITIES);
+ } else {
+ tcpm_set_state(port, SOFT_RESET_SEND, 0);
+ }
+ break;
+ case PD_EXT_SOURCE_CAP_EXT:
case PD_EXT_BATT_CAP:
case PD_EXT_GET_MANUFACTURER_INFO:
case PD_EXT_MANUFACTURER_INFO:
@@ -4261,6 +4335,14 @@ static bool tcpm_send_queued_message(struct tcpm_port *port)
ret);
tcpm_ams_finish(port);
break;
+ case PD_MSG_EXT_BATT_CAP:
+ ret = tcpm_pd_send_batt_cap(port);
+ if (ret)
+ tcpm_log(port,
+ "Failed to send battery cap ret=%d",
+ ret);
+ tcpm_ams_finish(port);
+ break;
default:
break;
}
diff --git a/include/linux/usb/pd.h b/include/linux/usb/pd.h
index afb9c2c65588..10ff4af7dedc 100644
--- a/include/linux/usb/pd.h
+++ b/include/linux/usb/pd.h
@@ -106,6 +106,9 @@ enum pd_ext_msg_type {
#define PD_HEADER_LE(type, pwr, data, rev, id, cnt) \
cpu_to_le16(PD_HEADER((type), (pwr), (data), (rev), (id), (cnt), (0)))
+#define PD_HEADER_EXT_LE(type, pwr, data, rev, id, cnt) \
+ cpu_to_le16(PD_HEADER((type), (pwr), (data), (rev), (id), (cnt), (1)))
+
static inline unsigned int pd_header_cnt(u16 header)
{
return (header >> PD_HEADER_CNT_SHIFT) & PD_HEADER_CNT_MASK;
@@ -219,6 +222,25 @@ static inline u8 count_chunked_data_objs(u32 size)
return ((size / 4) + (size % 4 ? 1 : 0));
}
+/**
+ * batt_cap_ext_msg - Battery capability extended PD message
+ * @vid: Battery Vendor ID (assigned by USB-IF)
+ * @pid: Battery Product ID (assigned by battery or device vendor)
+ * @batt_design_cap: Battery design capacity in 0.1Wh
+ * @batt_last_chg_cap: Battery last full charge capacity in 0.1Wh
+ * @batt_type: Battery Type. bit0 when set indicates invalid battery reference.
+ * Rest of the bits are reserved.
+ */
+struct batt_cap_ext_msg {
+ __le16 vid;
+ __le16 pid;
+ __le16 batt_design_cap;
+ __le16 batt_last_chg_cap;
+ u8 batt_type;
+} __packed;
+
+#define BATT_CAP_BATT_TYPE_INVALID_REF BIT(0)
+
/* Sink Caps Extended Data Block Version */
#define SKEDB_VER_1_0 1
---
base-commit: 0e35b9b6ec0ffcc5e23cbdec09f5c622ad532b53
change-id: 20260714-batt-caps-upstream-57f2cbe8eed3
prerequisite-change-id: 20260501-batt-status-16b6761c0bb1:v5
prerequisite-patch-id: 39dd78a0bb18e681fcd8efb01b6879dbeb881a3a
prerequisite-patch-id: 621fa71ad856f4b3246ec480ab17f8089b082932
Best regards,
--
Amit Sunil Dhamne <amitsd@xxxxxxxxxx>