[RFC net-next v2 04/14] net: stmmac: dwmac4/5: Add MAC loopback support

[Jose Abreu <Jose.Abreu@synopsys.com>]

In preparation for the addition of stmmac selftests we implement the MAC
loopback callback in dwmac4/5 cores.

Signed-off-by: Jose Abreu <joabreu@synopsys.com>
Cc: Joao Pinto <jpinto@synopsys.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Cc: Alexandre Torgue <alexandre.torgue@st.com>
Cc: Corentin Labbe <clabbe.montjoie@gmail.com>
---
 drivers/net/ethernet/stmicro/stmmac/dwmac4.h      |  1 +
 drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c | 15 +++++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac4.h b/drivers/net/ethernet/stmicro/stmmac/dwmac4.h
index eb013d54025a..3dddd7902b0f 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac4.h
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac4.h
@@ -160,6 +160,7 @@ enum power_event {
 #define GMAC_CONFIG_PS			BIT(15)
 #define GMAC_CONFIG_FES			BIT(14)
 #define GMAC_CONFIG_DM			BIT(13)
+#define GMAC_CONFIG_LM			BIT(12)
 #define GMAC_CONFIG_DCRS		BIT(9)
 #define GMAC_CONFIG_TE			BIT(1)
 #define GMAC_CONFIG_RE			BIT(0)
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c b/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c
index 7e5d5db0d516..2f1a2a6f9b33 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c
@@ -701,6 +701,18 @@ static void dwmac4_debug(void __iomem *ioaddr, struct stmmac_extra_stats *x,
 		x->mac_gmii_rx_proto_engine++;
 }
 
+static void dwmac4_set_mac_loopback(void __iomem *ioaddr, bool enable)
+{
+	u32 value = readl(ioaddr + GMAC_CONFIG);
+
+	if (enable)
+		value |= GMAC_CONFIG_LM;
+	else
+		value &= ~GMAC_CONFIG_LM;
+
+	writel(value, ioaddr + GMAC_CONFIG);
+}
+
 const struct stmmac_ops dwmac4_ops = {
 	.core_init = dwmac4_core_init,
 	.set_mac = stmmac_set_mac,
@@ -730,6 +742,7 @@ const struct stmmac_ops dwmac4_ops = {
 	.pcs_get_adv_lp = dwmac4_get_adv_lp,
 	.debug = dwmac4_debug,
 	.set_filter = dwmac4_set_filter,
+	.set_mac_loopback = dwmac4_set_mac_loopback,
 };
 
 const struct stmmac_ops dwmac410_ops = {
@@ -761,6 +774,7 @@ const struct stmmac_ops dwmac410_ops = {
 	.pcs_get_adv_lp = dwmac4_get_adv_lp,
 	.debug = dwmac4_debug,
 	.set_filter = dwmac4_set_filter,
+	.set_mac_loopback = dwmac4_set_mac_loopback,
 };
 
 const struct stmmac_ops dwmac510_ops = {
@@ -797,6 +811,7 @@ const struct stmmac_ops dwmac510_ops = {
 	.safety_feat_dump = dwmac5_safety_feat_dump,
 	.rxp_config = dwmac5_rxp_config,
 	.flex_pps_config = dwmac5_flex_pps_config,
+	.set_mac_loopback = dwmac4_set_mac_loopback,
 };
 
 int dwmac4_setup(struct stmmac_priv *priv)
-- 
2.7.4