[PATCH net-next v4 05/10] net: phylink: Add some helpers for working with mac caps

[Sean Anderson]

This adds a table for converting between speed/duplex and mac
capabilities. It also adds a helper for getting the max speed/duplex
from some caps. It is intended to be used by Russell King's DSA phylink
series. The table will be used directly later in this series.

Co-developed-by: Russell King (Oracle) <rmk+kernel@xxxxxxxxxxxxxxx>
Signed-off-by: Russell King (Oracle) <rmk+kernel@xxxxxxxxxxxxxxx>
[ adapted to live in phylink.c ]
Signed-off-by: Sean Anderson <sean.anderson@xxxxxxxx>
---
This is adapted from [1].

[1] https://lore.kernel.org/netdev/E1oCNlE-006e3z-3T@xxxxxxxxxxxxxxxxxxxxxx/

Changes in v4:
- Wrap docstring to 80 columns

Changes in v3:
- New

 drivers/net/phy/phylink.c | 57 +++++++++++++++++++++++++++++++++++++++
 include/linux/phylink.h   |  2 ++
 2 files changed, 59 insertions(+)

diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index 68a58ab6a8ed..8a9da7449c73 100644
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -304,6 +304,63 @@ void phylink_caps_to_linkmodes(unsigned long *linkmodes, unsigned long caps)
 }
 EXPORT_SYMBOL_GPL(phylink_caps_to_linkmodes);
 
+static struct {
+	unsigned long mask;
+	int speed;
+	unsigned int duplex;
+} phylink_caps_params[] = {
+	{ MAC_400000FD, SPEED_400000, DUPLEX_FULL },
+	{ MAC_200000FD, SPEED_200000, DUPLEX_FULL },
+	{ MAC_100000FD, SPEED_100000, DUPLEX_FULL },
+	{ MAC_56000FD,  SPEED_56000,  DUPLEX_FULL },
+	{ MAC_50000FD,  SPEED_50000,  DUPLEX_FULL },
+	{ MAC_40000FD,  SPEED_40000,  DUPLEX_FULL },
+	{ MAC_25000FD,  SPEED_25000,  DUPLEX_FULL },
+	{ MAC_20000FD,  SPEED_20000,  DUPLEX_FULL },
+	{ MAC_10000FD,  SPEED_10000,  DUPLEX_FULL },
+	{ MAC_5000FD,   SPEED_5000,   DUPLEX_FULL },
+	{ MAC_2500FD,   SPEED_2500,   DUPLEX_FULL },
+	{ MAC_1000FD,   SPEED_1000,   DUPLEX_FULL },
+	{ MAC_1000HD,   SPEED_1000,   DUPLEX_HALF },
+	{ MAC_100FD,    SPEED_100,    DUPLEX_FULL },
+	{ MAC_100HD,    SPEED_100,    DUPLEX_HALF },
+	{ MAC_10FD,     SPEED_10,     DUPLEX_FULL },
+	{ MAC_10HD,     SPEED_10,     DUPLEX_HALF },
+};
+
+/**
+ * phylink_caps_find_max_speed() - Find the max speed/duplex of mac capabilities
+ * @caps: A mask of mac capabilities
+ * @speed: Variable to store the maximum speed
+ * @duplex: Variable to store the maximum duplex
+ *
+ * Find the maximum speed (and associated duplex) supported by a mask of mac
+ * capabilities. @speed and @duplex are always set, even if no matching mac
+ * capability was found.
+ *
+ * Return: 0 on success, or %-EINVAL if the maximum speed/duplex could not be
+ *         determined.
+ */
+int phylink_caps_find_max_speed(unsigned long caps, int *speed,
+				unsigned int *duplex)
+{
+	int i;
+
+	*speed = SPEED_UNKNOWN;
+	*duplex = DUPLEX_UNKNOWN;
+
+	for (i = 0; i < ARRAY_SIZE(phylink_caps_params); i++) {
+		if (caps & phylink_caps_params[i].mask) {
+			*speed = phylink_caps_params[i].speed;
+			*duplex = phylink_caps_params[i].duplex;
+			return 0;
+		}
+	}
+
+	return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(phylink_caps_find_max_speed);
+
 /**
  * phylink_get_capabilities() - get capabilities for a given MAC
  * @interface: phy interface mode defined by &typedef phy_interface_t
diff --git a/include/linux/phylink.h b/include/linux/phylink.h
index 661d1d4fdbec..a5a236cfacb6 100644
--- a/include/linux/phylink.h
+++ b/include/linux/phylink.h
@@ -535,6 +535,8 @@ void pcs_link_up(struct phylink_pcs *pcs, unsigned int mode,
 #endif
 
 void phylink_caps_to_linkmodes(unsigned long *linkmodes, unsigned long caps);
+int phylink_caps_find_max_speed(unsigned long caps, int *speed,
+				unsigned int *duplex);
 unsigned long phylink_get_capabilities(phy_interface_t interface,
 				       unsigned long mac_capabilities);
 void phylink_generic_validate(struct phylink_config *config,
-- 
2.35.1.1320.gc452695387.dirty