2 files changed, 66 insertions, 8 deletions

diff --git a/target/linux/ar71xx/files/arch/mips/include/asm/mach-ath79/ag71xx_platform.h b/target/linux/ar71xx/files/arch/mips/include/asm/mach-ath79/ag71xx_platform.h
index e2f6f9b113..656a6ef860 100644
--- a/target/linux/ar71xx/files/arch/mips/include/asm/mach-ath79/ag71xx_platform.h
+++ b/target/linux/ar71xx/files/arch/mips/include/asm/mach-ath79/ag71xx_platform.h
@@ -53,6 +53,8 @@ struct ag71xx_mdio_platform_data {
 	u8		is_ar7240:1;
 	u8		is_ar9330:1;
 	u8		is_ar934x:1;
+	unsigned long	mdio_clock;
+	unsigned long	ref_clock;
 };
 
 #endif /* __ASM_MACH_ATH79_PLATFORM_H */
diff --git a/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx_mdio.c b/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx_mdio.c
index eaaf121485..e123505c7a 100644
--- a/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx_mdio.c
+++ b/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx_mdio.c
@@ -105,19 +105,75 @@ void ag71xx_mdio_mii_write(struct ag71xx_mdio *am, int addr, int reg, u16 val)
 	ag71xx_mdio_wait_busy(am);
 }
 
+static const u32 ar71xx_mdio_div_table[] = {
+	4, 4, 6, 8, 10, 14, 20, 28,
+};
+
+static const u32 ar7240_mdio_div_table[] = {
+	2, 2, 4, 6, 8, 12, 18, 26, 32, 40, 48, 56, 62, 70, 78, 96,
+};
+
+static const u32 ar933x_mdio_div_table[] = {
+	4, 4, 6, 8, 10, 14, 20, 28, 34, 42, 50, 58, 66, 74, 82, 98,
+};
+
+static int ag71xx_mdio_get_divider(struct ag71xx_mdio *am, u32 *div)
+{
+	unsigned long ref_clock, mdio_clock;
+	const u32 *table;
+	int ndivs;
+	int i;
+
+	ref_clock = am->pdata->ref_clock;
+	mdio_clock = am->pdata->mdio_clock;
+
+	if (!ref_clock || !mdio_clock)
+		return -EINVAL;
+
+	if (am->pdata->is_ar9330 || am->pdata->is_ar934x) {
+		table = ar933x_mdio_div_table;
+		ndivs = ARRAY_SIZE(ar933x_mdio_div_table);
+	} else if (am->pdata->is_ar7240) {
+		table = ar7240_mdio_div_table;
+		ndivs = ARRAY_SIZE(ar7240_mdio_div_table);
+	} else {
+		table = ar71xx_mdio_div_table;
+		ndivs = ARRAY_SIZE(ar71xx_mdio_div_table);
+	}
+
+	for (i = 0; i < ndivs; i++) {
+		unsigned long t;
+
+		t = ref_clock / table[i];
+		if (t <= mdio_clock) {
+			*div = i;
+			return 0;
+		}
+	}
+
+	dev_err(&am->mii_bus->dev, "no divider found for %lu/%lu\n",
+		ref_clock, mdio_clock);
+	return -ENOENT;
+}
+
 static int ag71xx_mdio_reset(struct mii_bus *bus)
 {
 	struct ag71xx_mdio *am = bus->priv;
 	u32 t;
+	int err;
 
-	if (am->pdata->is_ar7240)
-		t = MII_CFG_CLK_DIV_6;
-	else if (am->pdata->builtin_switch && !am->pdata->is_ar934x)
-		t = MII_CFG_CLK_DIV_10;
-	else if (!am->pdata->builtin_switch && am->pdata->is_ar934x)
-		t = MII_CFG_CLK_DIV_58;
-	else
-		t = MII_CFG_CLK_DIV_28;
+	err = ag71xx_mdio_get_divider(am, &t);
+	if (err) {
+		/* fallback */
+		if (am->pdata->is_ar7240)
+			t = MII_CFG_CLK_DIV_6;
+		else if (am->pdata->builtin_switch && !am->pdata->is_ar934x)
+			t = MII_CFG_CLK_DIV_10;
+		else if (!am->pdata->builtin_switch && am->pdata->is_ar934x)
+			t = MII_CFG_CLK_DIV_58;
+		else
+			t = MII_CFG_CLK_DIV_28;
+	}
 
 	ag71xx_mdio_wr(am, AG71XX_REG_MII_CFG, t | MII_CFG_RESET);
 	udelay(100);