[RFC PATCH 4/4] power: supply: qcom_battmgr: Allow charger changes to wake up the system

[Vladyslav Tymoshchuk <tvlad744@gmail.com>]

The battery manager notifies about changes of the battery state, many
of which arrive while the system is asleep, and about changes of the
USB and wireless charger properties, a charger being plugged in or out
for one. Only the latter can be worth a wakeup, to show the new
charging state for example.

Make the device wakeup capable, and set a wakeup filter that lets
pmic_glink report only the charger notifications as wakeup events.
Leave wakeup disabled, so that nothing changes by default: whether a
charger change should wake up the system is up to user space, through
power/wakeup.

Signed-off-by: Vladyslav Tymoshchuk <tvlad744@gmail.com>
---
I used an AI assistant (Claude) for the analysis and to draft this
patch and its description; I reviewed the result. The testing is
described in the cover letter.

 drivers/power/supply/qcom_battmgr.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/drivers/power/supply/qcom_battmgr.c b/drivers/power/supply/qcom_battmgr.c
index 636d6f6acecc..7a783a3a320d 100644
--- a/drivers/power/supply/qcom_battmgr.c
+++ b/drivers/power/supply/qcom_battmgr.c
@@ -10,6 +10,7 @@
 #include <linux/mutex.h>
 #include <linux/nvmem-consumer.h>
 #include <linux/of_device.h>
+#include <linux/pm_wakeup.h>
 #include <linux/power_supply.h>
 #include <linux/property.h>
 #include <linux/soc/qcom/pdr.h>
@@ -1596,6 +1597,20 @@ static void qcom_battmgr_sm8350_callback(struct qcom_battmgr *battmgr,
 	complete(&battmgr->ack);
 }
 
+static bool qcom_battmgr_is_charger_notification(const void *data, size_t len, void *priv)
+{
+	const struct qcom_battmgr_message *msg = data;
+	unsigned int notification;
+
+	if (le32_to_cpu(msg->hdr.opcode) != BATTMGR_NOTIFICATION ||
+	    len != sizeof(msg->hdr) + sizeof(msg->notification))
+		return false;
+
+	notification = le32_to_cpu(msg->notification) & 0xff;
+
+	return notification == NOTIF_USB_PROPERTY || notification == NOTIF_WLS_PROPERTY;
+}
+
 static void qcom_battmgr_callback(const void *data, size_t len, void *priv)
 {
 	const struct pmic_glink_hdr *hdr = data;
@@ -1750,6 +1765,10 @@ static int qcom_battmgr_probe(struct auxiliary_device *adev,
 	if (IS_ERR(battmgr->client))
 		return PTR_ERR(battmgr->client);
 
+	device_set_wakeup_capable(dev, true);
+	pmic_glink_client_set_wakeup_filter(battmgr->client,
+					    qcom_battmgr_is_charger_notification);
+
 	pmic_glink_client_register(battmgr->client);
 
 	return 0;
-- 
2.43.0