[PATCH net-next v5 08/14] net: renesas: rswitch: add locking for agent clock control

[Michael Dege]

RCEC and RCDC clock registers are shared by all ports (ETHA and GWCA),
there is a potential risk of a race condition leading to an undefined
state.

Signed-off-by: Michael Dege <michael.dege@xxxxxxxxxxx>
---
 drivers/net/ethernet/renesas/rswitch.h      |  3 +++
 drivers/net/ethernet/renesas/rswitch_main.c | 17 +++++++++++++++--
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/renesas/rswitch.h b/drivers/net/ethernet/renesas/rswitch.h
index 5feeb555e9a8..f85dd96a9bfb 100644
--- a/drivers/net/ethernet/renesas/rswitch.h
+++ b/drivers/net/ethernet/renesas/rswitch.h
@@ -1089,6 +1089,7 @@ struct rswitch_etha {
 	unsigned int index;
 	void __iomem *addr;
 	void __iomem *coma_addr;
+	struct rswitch_private *priv;
 	bool external_phy;
 	struct mii_bus *mii;
 	phy_interface_t phy_interface;
@@ -1207,6 +1208,8 @@ struct rswitch_private {
 	struct list_head port_list;
 
 	spinlock_t lock;	/* lock interrupt registers' control */
+	spinlock_t agent_lock;	/* rswitch agent clock control */
+
 	struct clk *clk;
 
 	bool etha_no_runtime_change;
diff --git a/drivers/net/ethernet/renesas/rswitch_main.c b/drivers/net/ethernet/renesas/rswitch_main.c
index 20ac8f3b9357..fc80c65c2131 100644
--- a/drivers/net/ethernet/renesas/rswitch_main.c
+++ b/drivers/net/ethernet/renesas/rswitch_main.c
@@ -173,8 +173,12 @@ int rswitch_gwca_change_mode(struct rswitch_private *priv,
 {
 	int ret;
 
-	if (!rswitch_agent_clock_is_enabled(priv->addr, priv->gwca.index))
+	if (!rswitch_agent_clock_is_enabled(priv->addr, priv->gwca.index)) {
+		spin_lock(&priv->agent_lock);
 		rswitch_agent_clock_ctrl(priv->addr, priv->gwca.index, 1);
+		spin_lock(&priv->agent_lock);
+	}
+
 	iowrite32(GWMC_OPC_DISABLE, priv->addr + GWMC);
 
 	ret = rswitch_reg_wait(priv->addr, GWMS, GWMS_OPS_MASK, GWMC_OPC_DISABLE);
@@ -182,7 +186,9 @@ int rswitch_gwca_change_mode(struct rswitch_private *priv,
 		return ret;
 
 	if (mode == GWMC_OPC_DISABLE) {
+		spin_lock(&priv->agent_lock);
 		rswitch_agent_clock_ctrl(priv->addr, priv->gwca.index, 0);
+		spin_unlock(&priv->agent_lock);
 
 		return ret;
 	}
@@ -1183,15 +1189,21 @@ int rswitch_etha_change_mode(struct rswitch_etha *etha,
 {
 	int ret;
 
-	if (!rswitch_agent_clock_is_enabled(etha->coma_addr, etha->index))
+	if (!rswitch_agent_clock_is_enabled(etha->coma_addr, etha->index)) {
+		spin_lock(&etha->priv->agent_lock);
 		rswitch_agent_clock_ctrl(etha->coma_addr, etha->index, 1);
+		spin_unlock(&etha->priv->agent_lock);
+	}
+
 	iowrite32(EAMC_OPC_DISABLE, etha->addr + EAMC);
 	ret = rswitch_reg_wait(etha->addr, EAMS, EAMS_OPS_MASK, EAMC_OPC_DISABLE);
 	if (ret < 0)
 		return ret;
 
 	if (mode == EAMC_OPC_DISABLE) {
+		spin_lock(&etha->priv->agent_lock);
 		rswitch_agent_clock_ctrl(etha->coma_addr, etha->index, 0);
+		spin_unlock(&etha->priv->agent_lock);
 
 		return ret;
 	}
@@ -2010,6 +2022,7 @@ static void rswitch_etha_init(struct rswitch_private *priv, unsigned int index)
 	etha->index = index;
 	etha->addr = priv->addr + RSWITCH_ETHA_OFFSET + index * RSWITCH_ETHA_SIZE;
 	etha->coma_addr = priv->addr;
+	etha->priv = priv;
 
 	/* MPIC.PSMCS = (clk [MHz] / (MDC frequency [MHz] * 2) - 1.
 	 * Calculating PSMCS value as MDC frequency = 2.5MHz. So, multiply

-- 
2.43.0