net: stmmac: implement the SIOCGHWTSTAMP ioctl

This patch adds support for the SIOCGHWTSTAMP ioctl which enables user
processes to read the current hwtstamp_config settings
non-destructively.
Signed-off-by: Artem Panfilov <panfilov.artyom@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -28,6 +28,7 @@
 #include <linux/pci.h>
 #include "common.h"
 #include <linux/ptp_clock_kernel.h>
+#include <linux/net_tstamp.h>
 #include <linux/reset.h>
 
 struct stmmac_resources {
@@ -174,6 +175,7 @@ struct stmmac_priv {
 	unsigned int mode;
 	unsigned int chain_mode;
 	int extend_desc;
+	struct hwtstamp_config tstamp_config;
 	struct ptp_clock *ptp_clock;
 	struct ptp_clock_info ptp_clock_ops;
 	unsigned int default_addend;

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

@@ -534,7 +534,7 @@ static void stmmac_get_rx_hwtstamp(struct stmmac_priv *priv, struct dma_desc *p,
 }
 
 /**
- *  stmmac_hwtstamp_ioctl - control hardware timestamping.
+ *  stmmac_hwtstamp_set - control hardware timestamping.
  *  @dev: device pointer.
  *  @ifr: An IOCTL specific structure, that can contain a pointer to
  *  a proprietary structure used to pass information to the driver.
@@ -544,7 +544,7 @@ static void stmmac_get_rx_hwtstamp(struct stmmac_priv *priv, struct dma_desc *p,
  *  Return Value:
  *  0 on success and an appropriate -ve integer on failure.
  */
-static int stmmac_hwtstamp_ioctl(struct net_device *dev, struct ifreq *ifr)
+static int stmmac_hwtstamp_set(struct net_device *dev, struct ifreq *ifr)
 {
 	struct stmmac_priv *priv = netdev_priv(dev);
 	struct hwtstamp_config config;
@@ -573,7 +573,7 @@ static int stmmac_hwtstamp_ioctl(struct net_device *dev, struct ifreq *ifr)
 	}
 
 	if (copy_from_user(&config, ifr->ifr_data,
-			   sizeof(struct hwtstamp_config)))
+			   sizeof(config)))
 		return -EFAULT;
 
 	netdev_dbg(priv->dev, "%s config flags:0x%x, tx_type:0x%x, rx_filter:0x%x\n",
@@ -765,8 +765,31 @@ static int stmmac_hwtstamp_ioctl(struct net_device *dev, struct ifreq *ifr)
 				(u32)now.tv_sec, now.tv_nsec);
 	}
 
+	memcpy(&priv->tstamp_config, &config, sizeof(config));
+
 	return copy_to_user(ifr->ifr_data, &config,
-			    sizeof(struct hwtstamp_config)) ? -EFAULT : 0;
+			    sizeof(config)) ? -EFAULT : 0;
+}
+
+/**
+ *  stmmac_hwtstamp_get - read hardware timestamping.
+ *  @dev: device pointer.
+ *  @ifr: An IOCTL specific structure, that can contain a pointer to
+ *  a proprietary structure used to pass information to the driver.
+ *  Description:
+ *  This function obtain the current hardware timestamping settings
+    as requested.
+ */
+static int stmmac_hwtstamp_get(struct net_device *dev, struct ifreq *ifr)
+{
+	struct stmmac_priv *priv = netdev_priv(dev);
+	struct hwtstamp_config *config = &priv->tstamp_config;
+
+	if (!(priv->dma_cap.time_stamp || priv->dma_cap.atime_stamp))
+		return -EOPNOTSUPP;
+
+	return copy_to_user(ifr->ifr_data, config,
+			    sizeof(*config)) ? -EFAULT : 0;
 }
 
 /**
@@ -3767,7 +3790,10 @@ static int stmmac_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
 		ret = phy_mii_ioctl(dev->phydev, rq, cmd);
 		break;
 	case SIOCSHWTSTAMP:
-		ret = stmmac_hwtstamp_ioctl(dev, rq);
+		ret = stmmac_hwtstamp_set(dev, rq);
+		break;
+	case SIOCGHWTSTAMP:
+		ret = stmmac_hwtstamp_get(dev, rq);
 		break;
 	default:
 		break;