net: stmmac: Add support for optional reset control

The DWMAC has a reset assert line, which is used on some SoCs. Add an
optional reset control to stmmac driver core.

To support reset control deferred probing, this patch changes the driver
probe function to return the actual error, instead of just -EINVAL.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 25 insertions, 5 deletions

diff --git a/drivers/net/ethernet/stmicro/stmmac/Kconfig b/drivers/net/ethernet/stmicro/stmmac/Kconfig
index 6e52c0f74cd..b59d1ef5f6d 100644
--- a/drivers/net/ethernet/stmicro/stmmac/Kconfig
+++ b/drivers/net/ethernet/stmicro/stmmac/Kconfig
@@ -5,6 +5,7 @@ config STMMAC_ETH
 	select PHYLIB
 	select CRC32
 	select PTP_1588_CLOCK
+	select RESET_CONTROLLER
 	---help---
 	  This is the driver for the Ethernet IPs are built around a
 	  Synopsys IP Core and only tested on the STMicroelectronics
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac.h b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
index 73709e9ddcd..c1c141fe15e 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac.h
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
@@ -32,6 +32,7 @@
 #include <linux/pci.h>
 #include "common.h"
 #include <linux/ptp_clock_kernel.h>
+#include <linux/reset.h>
 
 struct stmmac_priv {
 	/* Frequently used values are kept adjacent for cache effect */
@@ -91,6 +92,7 @@ struct stmmac_priv {
 	int wolopts;
 	int wol_irq;
 	struct clk *stmmac_clk;
+	struct reset_control *stmmac_rst;
 	int clk_csr;
 	struct timer_list eee_ctrl_timer;
 	int lpi_irq;
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 0d2c4cb0996..0c5c1208900 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -51,6 +51,7 @@
 #include <linux/net_tstamp.h>
 #include "stmmac_ptp.h"
 #include "stmmac.h"
+#include <linux/reset.h>
 
 #define STMMAC_ALIGN(x)	L1_CACHE_ALIGN(x)
 #define JUMBO_LEN	9000
@@ -2728,10 +2729,24 @@ struct stmmac_priv *stmmac_dvr_probe(struct device *device,
 	if (IS_ERR(priv->stmmac_clk)) {
 		dev_warn(priv->device, "%s: warning: cannot get CSR clock\n",
 			 __func__);
+		ret = PTR_ERR(priv->stmmac_clk);
 		goto error_clk_get;
 	}
 	clk_prepare_enable(priv->stmmac_clk);
 
+	priv->stmmac_rst = devm_reset_control_get(priv->device,
+						  STMMAC_RESOURCE_NAME);
+	if (IS_ERR(priv->stmmac_rst)) {
+		if (PTR_ERR(priv->stmmac_rst) == -EPROBE_DEFER) {
+			ret = -EPROBE_DEFER;
+			goto error_hw_init;
+		}
+		dev_info(priv->device, "no reset control found\n");
+		priv->stmmac_rst = NULL;
+	}
+	if (priv->stmmac_rst)
+		reset_control_deassert(priv->stmmac_rst);
+
 	/* Init MAC and get the capabilities */
 	ret = stmmac_hw_init(priv);
 	if (ret)
@@ -2808,7 +2823,7 @@ error_hw_init:
 error_clk_get:
 	free_netdev(ndev);
 
-	return NULL;
+	return ERR_PTR(ret);
 }
 
 /**
@@ -2832,6 +2847,8 @@ int stmmac_dvr_remove(struct net_device *ndev)
 		stmmac_mdio_unregister(ndev);
 	netif_carrier_off(ndev);
 	unregister_netdev(ndev);
+	if (priv->stmmac_rst)
+		reset_control_assert(priv->stmmac_rst);
 	clk_disable_unprepare(priv->stmmac_clk);
 	free_netdev(ndev);
 
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_pci.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_pci.c
index 37ba2e08082..29160892484 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_pci.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_pci.c
@@ -100,9 +100,9 @@ static int stmmac_pci_probe(struct pci_dev *pdev,
 	stmmac_default_data();
 
 	priv = stmmac_dvr_probe(&(pdev->dev), &plat_dat, addr);
-	if (!priv) {
+	if (IS_ERR(priv)) {
 		pr_err("%s: main driver probe failed", __func__);
-		ret = -ENODEV;
+		ret = PTR_ERR(priv);
 		goto err_out;
 	}
 	priv->dev->irq = pdev->irq;
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
index 6d0bf222623..cc6b89a75f9 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
@@ -152,9 +152,9 @@ static int stmmac_pltfr_probe(struct platform_device *pdev)
 	}
 
 	priv = stmmac_dvr_probe(&(pdev->dev), plat_dat, addr);
-	if (!priv) {
+	if (IS_ERR(priv)) {
 		pr_err("%s: main driver probe failed", __func__);
-		return -ENODEV;
+		return PTR_ERR(priv);
 	}
 
 	/* Get MAC address if available (DT) */