net: sfp: add A2h presence flag

The hwmon code wants to know when it is safe to access the A2h data
stored in a separate address. We indicate that this is present when
we have SFF-8472 compliance and the lack of an address-change
sequence.,

The same conditions are also true if we want to access other controls
and status in the A2h address. So let's make a flag to indicate whether
we can access it, instead of repeating the conditions throughout the
code.

For now, only convert the hwmon code.
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/phy/sfp.c

@@ -255,6 +255,8 @@ struct sfp {
 	unsigned int module_power_mW;
 	unsigned int module_t_start_up;
 	unsigned int module_t_wait;
+
+	bool have_a2;
 	bool tx_fault_ignore;
 
 	const struct sfp_quirk *quirk;
@@ -1453,20 +1455,10 @@ static void sfp_hwmon_probe(struct work_struct *work)
 
 static int sfp_hwmon_insert(struct sfp *sfp)
 {
-	if (sfp->id.ext.sff8472_compliance == SFP_SFF8472_COMPLIANCE_NONE)
-		return 0;
-
-	if (!(sfp->id.ext.diagmon & SFP_DIAGMON_DDM))
-		return 0;
-
-	if (sfp->id.ext.diagmon & SFP_DIAGMON_ADDRMODE)
-		/* This driver in general does not support address
-		 * change.
-		 */
-		return 0;
-
-	mod_delayed_work(system_wq, &sfp->hwmon_probe, 1);
-	sfp->hwmon_tries = R_PROBE_RETRY_SLOW;
+	if (sfp->have_a2 && sfp->id.ext.diagmon & SFP_DIAGMON_DDM) {
+		mod_delayed_work(system_wq, &sfp->hwmon_probe, 1);
+		sfp->hwmon_tries = R_PROBE_RETRY_SLOW;
+	}
 
 	return 0;
 }
@@ -1916,6 +1908,18 @@ static int sfp_cotsworks_fixup_check(struct sfp *sfp, struct sfp_eeprom_id *id)
 	return 0;
 }
 
+static int sfp_module_parse_sff8472(struct sfp *sfp)
+{
+	/* If the module requires address swap mode, warn about it */
+	if (sfp->id.ext.diagmon & SFP_DIAGMON_ADDRMODE)
+		dev_warn(sfp->dev,
+			 "module address swap to access page 0xA2 is not supported.\n");
+	else
+		sfp->have_a2 = true;
+
+	return 0;
+}
+
 static int sfp_sm_mod_probe(struct sfp *sfp, bool report)
 {
 	/* SFP module inserted - read I2C data */
@@ -2053,10 +2057,11 @@ static int sfp_sm_mod_probe(struct sfp *sfp, bool report)
 		return -EINVAL;
 	}
 
-	/* If the module requires address swap mode, warn about it */
-	if (sfp->id.ext.diagmon & SFP_DIAGMON_ADDRMODE)
-		dev_warn(sfp->dev,
-			 "module address swap to access page 0xA2 is not supported.\n");
+	if (sfp->id.ext.sff8472_compliance != SFP_SFF8472_COMPLIANCE_NONE) {
+		ret = sfp_module_parse_sff8472(sfp);
+		if (ret < 0)
+			return ret;
+	}
 
 	/* Parse the module power requirement */
 	ret = sfp_module_parse_power(sfp);
@@ -2103,6 +2108,7 @@ static void sfp_sm_mod_remove(struct sfp *sfp)
 
 	memset(&sfp->id, 0, sizeof(sfp->id));
 	sfp->module_power_mW = 0;
+	sfp->have_a2 = false;
 
 	dev_info(sfp->dev, "module removed\n");
 }