net: ethernet: stmmac: Add support for syscfg clock

Add optional support for syscfg clock in dwmac-stm32.c
Now Syscfg clock is activated automatically when syscfg
registers are used
Signed-off-by: NChristophe Roullier <christophe.roullier@st.com>
Reviewed-by: NAndrew Lunn <andrew@lunn.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/dwmac-stm32.c

@@ -155,18 +155,14 @@ static int stm32mp1_clk_prepare(struct stm32_dwmac *dwmac, bool prepare)
 		ret = clk_prepare_enable(dwmac->syscfg_clk);
 		if (ret)
 			return ret;
-
-		if (dwmac->clk_eth_ck) {
-			ret = clk_prepare_enable(dwmac->clk_eth_ck);
-			if (ret) {
-				clk_disable_unprepare(dwmac->syscfg_clk);
+		ret = clk_prepare_enable(dwmac->clk_eth_ck);
+		if (ret) {
+			clk_disable_unprepare(dwmac->syscfg_clk);
 				return ret;
-			}
 		}
 	} else {
 		clk_disable_unprepare(dwmac->syscfg_clk);
-		if (dwmac->clk_eth_ck)
-			clk_disable_unprepare(dwmac->clk_eth_ck);
+		clk_disable_unprepare(dwmac->clk_eth_ck);
 	}
 	return ret;
 }
@@ -320,12 +316,10 @@ static int stm32mp1_parse_data(struct stm32_dwmac *dwmac,
 		return PTR_ERR(dwmac->clk_ethstp);
 	}
 
-	/*  Clock for sysconfig */
+	/*  Optional Clock for sysconfig */
 	dwmac->syscfg_clk = devm_clk_get(dev, "syscfg-clk");
-	if (IS_ERR(dwmac->syscfg_clk)) {
-		dev_err(dev, "No syscfg clock provided...\n");
-		return PTR_ERR(dwmac->syscfg_clk);
-	}
+	if (IS_ERR(dwmac->syscfg_clk))
+		dwmac->syscfg_clk = NULL;
 
 	/* Get IRQ information early to have an ability to ask for deferred
 	 * probe if needed before we went too far with resource allocation.
@@ -437,8 +431,7 @@ static int stm32mp1_suspend(struct stm32_dwmac *dwmac)
 
 	clk_disable_unprepare(dwmac->clk_tx);
 	clk_disable_unprepare(dwmac->syscfg_clk);
-	if (dwmac->clk_eth_ck)
-		clk_disable_unprepare(dwmac->clk_eth_ck);
+	clk_disable_unprepare(dwmac->clk_eth_ck);
 
 	return ret;
 }