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

[Amit Sunil Dhamne via B4 Relay <devnull+amitsd.google.com@kernel.org>]

From: Amit Sunil Dhamne <amitsd@google.com>

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@google.com>
Reviewed-by: Badhri Jagan Sridharan <badhri@google.com>
---
 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