From: Russell King <rmk+kernel@armlinux.org.uk>
Date: Wed, 11 Dec 2019 10:56:09 +0000
Subject: net: sfp: add module start/stop upstream notifications
Patch-mainline: v5.6-rc1
Git-commit: 74c551ca5a0edcc9cf66a3b73fd95b9a8615bfd0
References: bsc#1176447

When dealing with some copper modules, we can't positively know the
module capabilities are until we have probed the PHY. Without the full
capabilities, we may end up failing a module that we could otherwise
drive with a restricted set of capabilities.

An example of this would be a module with a NBASE-T PHY plugged into
a host that supports phy interface modes 2500BASE-X and SGMII. The
PHY supports 10GBASE-R, 5000BASE-X, 2500BASE-X, SGMII interface modes,
which means a subset of the capabilities are compatible with the host.

However, reading the module EEPROM leads us to believe that the module
only supports ethtool link mode 10GBASE-T, which is incompatible with
the host - and thus results in the module being rejected.

This patch adds an extra notification which are triggered after the
SFP module's PHY probe, and a corresponding notification just before
the PHY is removed.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/phy/sfp-bus.c |   21 +++++++++++++++++++++
 drivers/net/phy/sfp.c     |    8 ++++++++
 drivers/net/phy/sfp.h     |    2 ++
 include/linux/sfp.h       |    4 ++++
 4 files changed, 35 insertions(+)

--- a/drivers/net/phy/sfp-bus.c
+++ b/drivers/net/phy/sfp-bus.c
@@ -712,6 +712,27 @@ void sfp_module_remove(struct sfp_bus *b
 }
 EXPORT_SYMBOL_GPL(sfp_module_remove);
 
+int sfp_module_start(struct sfp_bus *bus)
+{
+	const struct sfp_upstream_ops *ops = sfp_get_upstream_ops(bus);
+	int ret = 0;
+
+	if (ops && ops->module_start)
+		ret = ops->module_start(bus->upstream);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(sfp_module_start);
+
+void sfp_module_stop(struct sfp_bus *bus)
+{
+	const struct sfp_upstream_ops *ops = sfp_get_upstream_ops(bus);
+
+	if (ops && ops->module_stop)
+		ops->module_stop(bus->upstream);
+}
+EXPORT_SYMBOL_GPL(sfp_module_stop);
+
 static void sfp_socket_clear(struct sfp_bus *bus)
 {
 	bus->sfp_dev = NULL;
--- a/drivers/net/phy/sfp.c
+++ b/drivers/net/phy/sfp.c
@@ -59,6 +59,7 @@ enum {
 	SFP_DEV_UP,
 
 	SFP_S_DOWN = 0,
+	SFP_S_FAIL,
 	SFP_S_WAIT,
 	SFP_S_INIT,
 	SFP_S_INIT_TX_FAULT,
@@ -122,6 +123,7 @@ static const char *event_to_str(unsigned
 
 static const char * const sm_state_strings[] = {
 	[SFP_S_DOWN] = "down",
+	[SFP_S_FAIL] = "fail",
 	[SFP_S_WAIT] = "wait",
 	[SFP_S_INIT] = "init",
 	[SFP_S_INIT_TX_FAULT] = "init_tx_fault",
@@ -1826,6 +1828,8 @@ static void sfp_sm_main(struct sfp *sfp,
 		if (sfp->sm_state == SFP_S_LINK_UP &&
 		    sfp->sm_dev_state == SFP_DEV_UP)
 			sfp_sm_link_down(sfp);
+		if (sfp->sm_state > SFP_S_INIT)
+			sfp_module_stop(sfp->sfp_bus);
 		if (sfp->mod_phy)
 			sfp_sm_phy_detach(sfp);
 		sfp_module_tx_disable(sfp);
@@ -1893,6 +1897,10 @@ static void sfp_sm_main(struct sfp *sfp,
 			 * clear.  Probe for the PHY and check the LOS state.
 			 */
 			sfp_sm_probe_for_phy(sfp);
+			if (sfp_module_start(sfp->sfp_bus)) {
+				sfp_sm_next(sfp, SFP_S_FAIL, 0);
+				break;
+			}
 			sfp_sm_link_check_los(sfp);
 
 			/* Reset the fault retry count */
--- a/drivers/net/phy/sfp.h
+++ b/drivers/net/phy/sfp.h
@@ -22,6 +22,8 @@ void sfp_link_up(struct sfp_bus *bus);
 void sfp_link_down(struct sfp_bus *bus);
 int sfp_module_insert(struct sfp_bus *bus, const struct sfp_eeprom_id *id);
 void sfp_module_remove(struct sfp_bus *bus);
+int sfp_module_start(struct sfp_bus *bus);
+void sfp_module_stop(struct sfp_bus *bus);
 int sfp_link_configure(struct sfp_bus *bus, const struct sfp_eeprom_id *id);
 struct sfp_bus *sfp_register_socket(struct device *dev, struct sfp *sfp,
 				    const struct sfp_socket_ops *ops);
--- a/include/linux/sfp.h
+++ b/include/linux/sfp.h
@@ -507,6 +507,8 @@ struct sfp_bus;
  * @module_insert: called after a module has been detected to determine
  *   whether the module is supported for the upstream device.
  * @module_remove: called after the module has been removed.
+ * @module_start: called after the PHY probe step
+ * @module_stop: called before the PHY is removed
  * @link_down: called when the link is non-operational for whatever
  *   reason.
  * @link_up: called when the link is operational.
@@ -520,6 +522,8 @@ struct sfp_upstream_ops {
 	void (*detach)(void *priv, struct sfp_bus *bus);
 	int (*module_insert)(void *priv, const struct sfp_eeprom_id *id);
 	void (*module_remove)(void *priv);
+	int (*module_start)(void *priv);
+	void (*module_stop)(void *priv);
 	void (*link_down)(void *priv);
 	void (*link_up)(void *priv);
 	int (*connect_phy)(void *priv, struct phy_device *);