phy: convert swphy register generation to tabular form

Convert the swphy register generation to tabular form which allows us
to eliminate multiple switch() statements.  This results in a smaller
object code size, more efficient, and easier to add support for faster
speeds.

Before:

Idx Name          Size      VMA       LMA       File off  Algn
  0 .text         00000164  00000000  00000000  00000034  2**2

   text    data     bss     dec     hex filename
    388       0       0     388     184 swphy.o

After:

Idx Name          Size      VMA       LMA       File off  Algn
  0 .text         000000fc  00000000  00000000  00000034  2**2
  5 .rodata       00000028  00000000  00000000  00000138  2**2

   text    data     bss     dec     hex filename
    324       0       0     324     144 swphy.o

Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/swphy.c

@@ -20,6 +20,72 @@
 
 #include "swphy.h"
 
+struct swmii_regs {
+	u16 bmcr;
+	u16 bmsr;
+	u16 lpa;
+	u16 lpagb;
+};
+
+enum {
+	SWMII_SPEED_10 = 0,
+	SWMII_SPEED_100,
+	SWMII_SPEED_1000,
+	SWMII_DUPLEX_HALF = 0,
+	SWMII_DUPLEX_FULL,
+};
+
+/*
+ * These two tables get bitwise-anded together to produce the final result.
+ * This means the speed table must contain both duplex settings, and the
+ * duplex table must contain all speed settings.
+ */
+static const struct swmii_regs speed[] = {
+	[SWMII_SPEED_10] = {
+		.bmcr  = BMCR_FULLDPLX,
+		.lpa   = LPA_10FULL | LPA_10HALF,
+	},
+	[SWMII_SPEED_100] = {
+		.bmcr  = BMCR_FULLDPLX | BMCR_SPEED100,
+		.bmsr  = BMSR_100FULL | BMSR_100HALF,
+		.lpa   = LPA_100FULL | LPA_100HALF,
+	},
+	[SWMII_SPEED_1000] = {
+		.bmcr  = BMCR_FULLDPLX | BMCR_SPEED1000,
+		.bmsr  = BMSR_ESTATEN,
+		.lpagb = LPA_1000FULL | LPA_1000HALF,
+	},
+};
+
+static const struct swmii_regs duplex[] = {
+	[SWMII_DUPLEX_HALF] = {
+		.bmcr  = ~BMCR_FULLDPLX,
+		.bmsr  = BMSR_ESTATEN | BMSR_100HALF,
+		.lpa   = LPA_10HALF | LPA_100HALF,
+		.lpagb = LPA_1000HALF,
+	},
+	[SWMII_DUPLEX_FULL] = {
+		.bmcr  = ~0,
+		.bmsr  = BMSR_ESTATEN | BMSR_100FULL,
+		.lpa   = LPA_10FULL | LPA_100FULL,
+		.lpagb = LPA_1000FULL,
+	},
+};
+
+static int swphy_decode_speed(int speed)
+{
+	switch (speed) {
+	case 1000:
+		return SWMII_SPEED_1000;
+	case 100:
+		return SWMII_SPEED_100;
+	case 10:
+		return SWMII_SPEED_10;
+	default:
+		return -EINVAL;
+	}
+}
+
 /**
  * swphy_update_regs - update MII register array with fixed phy state
  * @regs: array of 32 registers to update
@@ -30,81 +96,28 @@
  */
 int swphy_update_regs(u16 *regs, const struct fixed_phy_status *state)
 {
+	int speed_index, duplex_index;
 	u16 bmsr = BMSR_ANEGCAPABLE;
 	u16 bmcr = 0;
 	u16 lpagb = 0;
 	u16 lpa = 0;
 
-	if (state->duplex) {
-		switch (state->speed) {
-		case 1000:
-			bmsr |= BMSR_ESTATEN;
-			break;
-		case 100:
-			bmsr |= BMSR_100FULL;
-			break;
-		case 10:
-			bmsr |= BMSR_10FULL;
-			break;
-		default:
-			break;
-		}
-	} else {
-		switch (state->speed) {
-		case 1000:
-			bmsr |= BMSR_ESTATEN;
-			break;
-		case 100:
-			bmsr |= BMSR_100HALF;
-			break;
-		case 10:
-			bmsr |= BMSR_10HALF;
-			break;
-		default:
-			break;
-		}
+	speed_index = swphy_decode_speed(state->speed);
+	if (speed_index < 0) {
+		pr_warn("swphy: unknown speed\n");
+		return -EINVAL;
 	}
 
+	duplex_index = state->duplex ? SWMII_DUPLEX_FULL : SWMII_DUPLEX_HALF;
+
+	bmsr |= speed[speed_index].bmsr & duplex[duplex_index].bmsr;
+
 	if (state->link) {
 		bmsr |= BMSR_LSTATUS | BMSR_ANEGCOMPLETE;
 
-		if (state->duplex) {
-			bmcr |= BMCR_FULLDPLX;
-
-			switch (state->speed) {
-			case 1000:
-				bmcr |= BMCR_SPEED1000;
-				lpagb |= LPA_1000FULL;
-				break;
-			case 100:
-				bmcr |= BMCR_SPEED100;
-				lpa |= LPA_100FULL;
-				break;
-			case 10:
-				lpa |= LPA_10FULL;
-				break;
-			default:
-				pr_warn("swphy: unknown speed\n");
-				return -EINVAL;
-			}
-		} else {
-			switch (state->speed) {
-			case 1000:
-				bmcr |= BMCR_SPEED1000;
-				lpagb |= LPA_1000HALF;
-				break;
-			case 100:
-				bmcr |= BMCR_SPEED100;
-				lpa |= LPA_100HALF;
-				break;
-			case 10:
-				lpa |= LPA_10HALF;
-				break;
-			default:
-				pr_warn("swphy: unknown speed\n");
-				return -EINVAL;
-			}
-		}
+		bmcr  |= speed[speed_index].bmcr  & duplex[duplex_index].bmcr;
+		lpa   |= speed[speed_index].lpa   & duplex[duplex_index].lpa;
+		lpagb |= speed[speed_index].lpagb & duplex[duplex_index].lpagb;
 
 		if (state->pause)
 			lpa |= LPA_PAUSE_CAP;