net: stmmac: dwmac-rk: add support for rk3308 gmac

The Rockchip RK3308 SoC has a gmac with only the RMII interface signals
exposed.
This patch adds support for it.
Signed-off-by: Tobias Schramm <t.schramm@manjaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c

@@ -482,6 +482,54 @@ static const struct rk_gmac_ops rk3288_ops = {
 	.set_rmii_speed = rk3288_set_rmii_speed,
 };
 
+#define RK3308_GRF_MAC_CON0		0x04a0
+
+/* RK3308_GRF_MAC_CON0 */
+#define RK3308_GMAC_PHY_INTF_SEL_RMII	(GRF_CLR_BIT(2) | GRF_CLR_BIT(3) | \
+					GRF_BIT(4))
+#define RK3308_GMAC_FLOW_CTRL		GRF_BIT(3)
+#define RK3308_GMAC_FLOW_CTRL_CLR	GRF_CLR_BIT(3)
+#define RK3308_GMAC_SPEED_10M		GRF_CLR_BIT(0)
+#define RK3308_GMAC_SPEED_100M		GRF_BIT(0)
+
+static void rk3308_set_to_rmii(struct rk_priv_data *bsp_priv)
+{
+	struct device *dev = &bsp_priv->pdev->dev;
+
+	if (IS_ERR(bsp_priv->grf)) {
+		dev_err(dev, "Missing rockchip,grf property\n");
+		return;
+	}
+
+	regmap_write(bsp_priv->grf, RK3308_GRF_MAC_CON0,
+		     RK3308_GMAC_PHY_INTF_SEL_RMII);
+}
+
+static void rk3308_set_rmii_speed(struct rk_priv_data *bsp_priv, int speed)
+{
+	struct device *dev = &bsp_priv->pdev->dev;
+
+	if (IS_ERR(bsp_priv->grf)) {
+		dev_err(dev, "Missing rockchip,grf property\n");
+		return;
+	}
+
+	if (speed == 10) {
+		regmap_write(bsp_priv->grf, RK3308_GRF_MAC_CON0,
+			     RK3308_GMAC_SPEED_10M);
+	} else if (speed == 100) {
+		regmap_write(bsp_priv->grf, RK3308_GRF_MAC_CON0,
+			     RK3308_GMAC_SPEED_100M);
+	} else {
+		dev_err(dev, "unknown speed value for RMII! speed=%d", speed);
+	}
+}
+
+static const struct rk_gmac_ops rk3308_ops = {
+	.set_to_rmii = rk3308_set_to_rmii,
+	.set_rmii_speed = rk3308_set_rmii_speed,
+};
+
 #define RK3328_GRF_MAC_CON0	0x0900
 #define RK3328_GRF_MAC_CON1	0x0904
 #define RK3328_GRF_MAC_CON2	0x0908
@@ -1477,6 +1525,7 @@ static const struct of_device_id rk_gmac_dwmac_match[] = {
 	{ .compatible = "rockchip,rk3128-gmac", .data = &rk3128_ops },
 	{ .compatible = "rockchip,rk3228-gmac", .data = &rk3228_ops },
 	{ .compatible = "rockchip,rk3288-gmac", .data = &rk3288_ops },
+	{ .compatible = "rockchip,rk3308-gmac", .data = &rk3308_ops },
 	{ .compatible = "rockchip,rk3328-gmac", .data = &rk3328_ops },
 	{ .compatible = "rockchip,rk3366-gmac", .data = &rk3366_ops },
 	{ .compatible = "rockchip,rk3368-gmac", .data = &rk3368_ops },