net: pse-pd: Add power limit check

Checking only the current limit is not sufficient. According to the
standard, voltage can reach up to 57V and current up to 1.92A, which
exceeds the power limit described in the standard (99.9W). Add a power
limit check to prevent this.

Acked-by: Oleksij Rempel <[email protected]>
Signed-off-by: Kory Maincent <[email protected]>
Signed-off-by: Paolo Abeni <[email protected]>

Author: kmaincent

drivers/net/pse-pd/pse_core.c

@@ -877,6 +877,9 @@ int pse_ethtool_set_pw_limit(struct pse_control *psec,
 	int uV, uA, ret;
 	s64 tmp_64;
 
+	if (pw_limit > MAX_PI_PW)
+		return -ERANGE;
+
 	ret = regulator_get_voltage(psec->ps);
 	if (!ret) {
 		NL_SET_ERR_MSG(extack,

include/linux/pse-pd/pse.h

@@ -11,6 +11,8 @@
 
 /* Maximum current in uA according to IEEE 802.3-2022 Table 145-1 */
 #define MAX_PI_CURRENT 1920000
+/* Maximum power in mW according to IEEE 802.3-2022 Table 145-16 */
+#define MAX_PI_PW 99900
 
 struct phy_device;
 struct pse_controller_dev;