net: Introduce new feature setting ops

This introduces a new framework to handle device features setting.
It consists of:
  - new fields in struct net_device:
	+ hw_features - features that hw/driver supports toggling
	+ wanted_features - features that user wants enabled, when possible
  - new netdev_ops:
	+ feat = ndo_fix_features(dev, feat) - API checking constraints for
		enabling features or their combinations
	+ ndo_set_features(dev) - API updating hardware state to match
		changed dev->features
  - new ethtool commands:
	+ ETHTOOL_GFEATURES/ETHTOOL_SFEATURES: get/set dev->wanted_features
		and trigger device reconfiguration if resulting dev->features
		changed
	+ ETHTOOL_GSTRINGS(ETH_SS_FEATURES): get feature bits names (meaning)

Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 120 insertions, 2 deletions

diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
index 1908929204a9..806e716bb4fb 100644
--- a/include/linux/ethtool.h
+++ b/include/linux/ethtool.h
@@ -251,6 +251,7 @@ enum ethtool_stringset {
         ETH_SS_STATS,
         ETH_SS_PRIV_FLAGS,
         ETH_SS_NTUPLE_FILTERS,
+        ETH_SS_FEATURES,
 };
 
 /* for passing string sets for data tagging */
@@ -523,6 +524,87 @@ struct ethtool_flash {
         char    data[ETHTOOL_FLASH_MAX_FILENAME];
 };
 
+/* for returning and changing feature sets */
+
+/**
+ * struct ethtool_get_features_block - block with state of 32 features
+ * @available: mask of changeable features
+ * @requested: mask of features requested to be enabled if possible
+ * @active: mask of currently enabled features
+ * @never_changed: mask of features not changeable for any device
+ */
+struct ethtool_get_features_block {
+        __u32   available;
+        __u32   requested;
+        __u32   active;
+        __u32   never_changed;
+};
+
+/**
+ * struct ethtool_gfeatures - command to get state of device's features
+ * @cmd: command number = %ETHTOOL_GFEATURES
+ * @size: in: number of elements in the features[] array;
+ *       out: number of elements in features[] needed to hold all features
+ * @features: state of features
+ */
+struct ethtool_gfeatures {
+        __u32   cmd;
+        __u32   size;
+        struct ethtool_get_features_block features[0];
+};
+
+/**
+ * struct ethtool_set_features_block - block with request for 32 features
+ * @valid: mask of features to be changed
+ * @requested: values of features to be changed
+ */
+struct ethtool_set_features_block {
+        __u32   valid;
+        __u32   requested;
+};
+
+/**
+ * struct ethtool_sfeatures - command to request change in device's features
+ * @cmd: command number = %ETHTOOL_SFEATURES
+ * @size: array size of the features[] array
+ * @features: feature change masks
+ */
+struct ethtool_sfeatures {
+        __u32   cmd;
+        __u32   size;
+        struct ethtool_set_features_block features[0];
+};
+
+/*
+ * %ETHTOOL_SFEATURES changes features present in features[].valid to the
+ * values of corresponding bits in features[].requested. Bits in .requested
+ * not set in .valid or not changeable are ignored.
+ *
+ * Returns %EINVAL when .valid contains undefined or never-changable bits
+ * or size is not equal to required number of features words (32-bit blocks).
+ * Returns >= 0 if request was completed; bits set in the value mean:
+ *   %ETHTOOL_F_UNSUPPORTED - there were bits set in .valid that are not
+ *      changeable (not present in %ETHTOOL_GFEATURES' features[].available)
+ *      those bits were ignored.
+ *   %ETHTOOL_F_WISH - some or all changes requested were recorded but the
+ *      resulting state of bits masked by .valid is not equal to .requested.
+ *      Probably there are other device-specific constraints on some features
+ *      in the set. When %ETHTOOL_F_UNSUPPORTED is set, .valid is considered
+ *      here as though ignored bits were cleared.
+ *
+ * Meaning of bits in the masks are obtained by %ETHTOOL_GSSET_INFO (number of
+ * bits in the arrays - always multiple of 32) and %ETHTOOL_GSTRINGS commands
+ * for ETH_SS_FEATURES string set. First entry in the table corresponds to least
+ * significant bit in features[0] fields. Empty strings mark undefined features.
+ */
+enum ethtool_sfeatures_retval_bits {
+        ETHTOOL_F_UNSUPPORTED__BIT,
+        ETHTOOL_F_WISH__BIT,
+};
+
+#define ETHTOOL_F_UNSUPPORTED   (1 << ETHTOOL_F_UNSUPPORTED__BIT)
+#define ETHTOOL_F_WISH          (1 << ETHTOOL_F_WISH__BIT)
+
 #ifdef __KERNEL__
 
 #include <linux/rculist.h>
@@ -744,6 +826,9 @@ struct ethtool_ops {
 #define ETHTOOL_GRXFHINDIR      0x00000038 /* Get RX flow hash indir'n table */
 #define ETHTOOL_SRXFHINDIR      0x00000039 /* Set RX flow hash indir'n table */
 
+#define ETHTOOL_GFEATURES       0x0000003a /* Get device offload settings */
+#define ETHTOOL_SFEATURES       0x0000003b /* Change device offload settings */
+
 /* compatibility with older code */
 #define SPARC_ETH_GSET          ETHTOOL_GSET
 #define SPARC_ETH_SSET          ETHTOOL_SSET
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index dede3fdbb4be..85f67e225f60 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -791,6 +791,18 @@ struct netdev_tc_txq {
  *
  * int (*ndo_del_slave)(struct net_device *dev, struct net_device *slave_dev);
  *      Called to release previously enslaved netdev.
+ *
+ *      Feature/offload setting functions.
+ * u32 (*ndo_fix_features)(struct net_device *dev, u32 features);
+ *      Adjusts the requested feature flags according to device-specific
+ *      constraints, and returns the resulting flags. Must not modify
+ *      the device state.
+ *
+ * int (*ndo_set_features)(struct net_device *dev, u32 features);
+ *      Called to update device configuration to new features. Passed
+ *      feature set might be less than what was returned by ndo_fix_features()).
+ *      Must return >0 or -errno if it changed dev->features itself.
+ *
  */
 #define HAVE_NET_DEVICE_OPS
 struct net_device_ops {
@@ -874,6 +886,10 @@ struct net_device_ops {
                                                  struct net_device *slave_dev);
         int                     (*ndo_del_slave)(struct net_device *dev,
                                                  struct net_device *slave_dev);
+        u32                     (*ndo_fix_features)(struct net_device *dev,
+                                                    u32 features);
+        int                     (*ndo_set_features)(struct net_device *dev,
+                                                    u32 features);
 };
 
 /*
@@ -925,12 +941,18 @@ struct net_device {
         struct list_head        napi_list;
         struct list_head        unreg_list;
 
-        /* Net device features */
+        /* currently active device features */
         u32                     features;
-
+        /* user-changeable features */
+        u32                     hw_features;
+        /* user-requested features */
+        u32                     wanted_features;
         /* VLAN feature mask */
         u32                     vlan_features;
 
+        /* Net device feature bits; if you change something,
+         * also update netdev_features_strings[] in ethtool.c */
+
 #define NETIF_F_SG              1       /* Scatter/gather IO. */
 #define NETIF_F_IP_CSUM         2       /* Can checksum TCP/UDP over IPv4. */
 #define NETIF_F_NO_CSUM         4       /* Does not require checksum. F.e. loopack. */
@@ -966,6 +988,12 @@ struct net_device {
 #define NETIF_F_TSO6            (SKB_GSO_TCPV6 << NETIF_F_GSO_SHIFT)
 #define NETIF_F_FSO             (SKB_GSO_FCOE << NETIF_F_GSO_SHIFT)
 
+        /* Features valid for ethtool to change */
+        /* = all defined minus driver/device-class-related */
+#define NETIF_F_NEVER_CHANGE    (NETIF_F_HIGHDMA | NETIF_F_VLAN_CHALLENGED | \
+                                  NETIF_F_LLTX | NETIF_F_NETNS_LOCAL)
+#define NETIF_F_ETHTOOL_BITS    (0x1f3fffff & ~NETIF_F_NEVER_CHANGE)
+
         /* List of features with software fallbacks. */
 #define NETIF_F_GSO_SOFTWARE    (NETIF_F_TSO | NETIF_F_TSO_ECN | \
                                  NETIF_F_TSO6 | NETIF_F_UFO)
@@ -2428,8 +2456,13 @@ extern char *netdev_drivername(const struct net_device *dev, char *buffer, int l
 
 extern void linkwatch_run_queue(void);
 
+static inline u32 netdev_get_wanted_features(struct net_device *dev)
+{
+        return (dev->features & ~dev->hw_features) | dev->wanted_features;
+}
 u32 netdev_increment_features(u32 all, u32 one, u32 mask);
 u32 netdev_fix_features(struct net_device *dev, u32 features);
+void netdev_update_features(struct net_device *dev);
 
 void netif_stacked_transfer_operstate(const struct net_device *rootdev,
                                         struct net_device *dev);