net: stmmac: Enable CRC clipping bit

When the bit is set the last four bytes of the ethernet
packet type is stripped and dropped before forwarding.

Change-Id: I740a513c90a85e3a390984602fd12539e567fc11
Acked-by: Abhishek Chauhan <abchauha@qti.qualcomm.com>
Signed-off-by: Sunil Paidimarri <hisunil@codeaurora.org>

Documentation/devicetree/bindings/net/stmmac.txt

@@ -116,6 +116,10 @@ Optional properties:
 			- snps,high_credit: max write outstanding req. limit
 			- snps,low_credit: max read outstanding req. limit
 		- snps,priority: TX queue priority (Range: 0x0 to 0xF)
+- snps,crc_strip: this enables the CRC stripping feature in the hardware and the
+		  last four bytes of the ethernet packet type is stripped and
+		  dropped before forwarding.
+
 Examples:
 
 	stmmac_axi_setup: stmmac-axi-config {

drivers/net/ethernet/stmicro/stmmac/common.h

@@ -600,6 +600,7 @@ struct mac_device_info {
 	unsigned int pcs;
 	unsigned int pmt;
 	unsigned int ps;
+	unsigned int crc_strip_en;
 };
 
 struct stmmac_rx_routing {

drivers/net/ethernet/stmicro/stmmac/dwmac4.h

@@ -148,6 +148,7 @@ enum power_event {
 /* MAC config */
 #define GMAC_CONFIG_IPC			BIT(27)
 #define GMAC_CONFIG_2K			BIT(22)
+#define GMAC_CONFIG_CRC			BIT(21)
 #define GMAC_CONFIG_ACS			BIT(20)
 #define GMAC_CONFIG_BE			BIT(18)
 #define GMAC_CONFIG_JD			BIT(17)

drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c

@@ -35,10 +35,13 @@ static void dwmac4_core_init(struct mac_device_info *hw,
 	if (mtu > 2000)
 		value |= GMAC_CONFIG_JE;
 
+	if (hw->crc_strip_en)
+		value |= GMAC_CONFIG_CRC;
+
 	if (hw->ps) {
 		value |= GMAC_CONFIG_TE;
 
-		value &= hw->link.speed_mask;
+		value &= ~(hw->link.speed_mask);
 		switch (hw->ps) {
 		case SPEED_1000:
 			value |= hw->link.speed1000;

drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

@@ -2624,6 +2624,7 @@ static int stmmac_hw_setup(struct net_device *dev, bool init_ptp)
 			priv->hw->ps = 0;
 		}
 	}
+	priv->hw->crc_strip_en = priv->plat->crc_strip_en;
 
 	/* Initialize the MAC Core */
 	priv->hw->mac->core_init(priv->hw, dev);

drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c

@@ -391,6 +391,8 @@ stmmac_probe_config_dt(struct platform_device *pdev, const char **mac)
 	if (of_property_read_u32(np, "max-speed", &plat->max_speed))
 		plat->max_speed = -1;
 
+	plat->crc_strip_en = of_property_read_bool(np, "snps,crc_strip");
+
 	plat->bus_id = of_alias_get_id(np, "ethernet");
 	if (plat->bus_id < 0)
 		plat->bus_id = 0;

include/linux/stmmac.h

@@ -199,5 +199,6 @@ struct plat_stmmacenet_data {
 	unsigned int (*get_plat_tx_coal_frames)
 		(struct sk_buff *skb);
 	bool early_eth;
+	bool crc_strip_en;
 };
 #endif