ethtool: provide pause parameters with PAUSE_GET request

Implement PAUSE_GET request to get pause parameters of a network device.
These are traditionally available via ETHTOOL_GPAUSEPARAM ioctl request.

Signed-off-by: Michal Kubecek <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

Documentation/networking/ethtool-netlink.rst

···
   ``ETHTOOL_MSG_CHANNELS_SET``          set channel counts
   ``ETHTOOL_MSG_COALESCE_GET``          get coalescing parameters
   ``ETHTOOL_MSG_COALESCE_SET``          set coalescing parameters
+  ``ETHTOOL_MSG_PAUSE_GET``             get pause parameters
   ===================================== ================================
 
 Kernel to userspace:
···
   ``ETHTOOL_MSG_CHANNELS_NTF``          channel counts
   ``ETHTOOL_MSG_COALESCE_GET_REPLY``    coalescing parameters
   ``ETHTOOL_MSG_COALESCE_NTF``          coalescing parameters
+  ``ETHTOOL_MSG_PAUSE_GET_REPLY``       pause parameters
   ===================================== =================================
 
 ``GET`` requests are sent by userspace applications to retrieve device
···
 constraints on coalescing parameters and their values.
 
 
+PAUSE_GET
+============
+
+Gets channel counts like ``ETHTOOL_GPAUSE`` ioctl request.
+
+Request contents:
+
+  =====================================  ======  ==========================
+  ``ETHTOOL_A_PAUSE_HEADER``             nested  request header
+  =====================================  ======  ==========================
+
+Kernel response contents:
+
+  =====================================  ======  ==========================
+  ``ETHTOOL_A_PAUSE_HEADER``             nested  request header
+  ``ETHTOOL_A_PAUSE_AUTONEG``            bool    pause autonegotiation
+  ``ETHTOOL_A_PAUSE_RX``                 bool    receive pause frames
+  ``ETHTOOL_A_PAUSE_TX``                 bool    transmit pause frames
+  =====================================  ======  ==========================
+
+
+PAUSE_SET
+============
+
+Sets pause parameters like ``ETHTOOL_GPAUSEPARAM`` ioctl request.
+
+Request contents:
+
+  =====================================  ======  ==========================
+  ``ETHTOOL_A_PAUSE_HEADER``             nested  request header
+  ``ETHTOOL_A_PAUSE_AUTONEG``            bool    pause autonegotiation
+  ``ETHTOOL_A_PAUSE_RX``                 bool    receive pause frames
+  ``ETHTOOL_A_PAUSE_TX``                 bool    transmit pause frames
+  =====================================  ======  ==========================
+
+
 Request translation
 ===================
 
···
   ``ETHTOOL_SCOALESCE``               ``ETHTOOL_MSG_COALESCE_SET``
   ``ETHTOOL_GRINGPARAM``              ``ETHTOOL_MSG_RINGS_GET``
   ``ETHTOOL_SRINGPARAM``              ``ETHTOOL_MSG_RINGS_SET``
-  ``ETHTOOL_GPAUSEPARAM``             n/a
+  ``ETHTOOL_GPAUSEPARAM``             ``ETHTOOL_MSG_PAUSE_GET``
   ``ETHTOOL_SPAUSEPARAM``             n/a
   ``ETHTOOL_GRXCSUM``                 ``ETHTOOL_MSG_FEATURES_GET``
   ``ETHTOOL_SRXCSUM``                 ``ETHTOOL_MSG_FEATURES_SET``

include/uapi/linux/ethtool_netlink.h

···
 	ETHTOOL_MSG_CHANNELS_SET,
 	ETHTOOL_MSG_COALESCE_GET,
 	ETHTOOL_MSG_COALESCE_SET,
+	ETHTOOL_MSG_PAUSE_GET,
 
 	/* add new constants above here */
 	__ETHTOOL_MSG_USER_CNT,
···
 	ETHTOOL_MSG_CHANNELS_NTF,
 	ETHTOOL_MSG_COALESCE_GET_REPLY,
 	ETHTOOL_MSG_COALESCE_NTF,
+	ETHTOOL_MSG_PAUSE_GET_REPLY,
 
 	/* add new constants above here */
 	__ETHTOOL_MSG_KERNEL_CNT,
···
 	/* add new constants above here */
 	__ETHTOOL_A_COALESCE_CNT,
 	ETHTOOL_A_COALESCE_MAX = (__ETHTOOL_A_COALESCE_CNT - 1)
+};
+
+/* PAUSE */
+
+enum {
+	ETHTOOL_A_PAUSE_UNSPEC,
+	ETHTOOL_A_PAUSE_HEADER,				/* nest - _A_HEADER_* */
+	ETHTOOL_A_PAUSE_AUTONEG,			/* u8 */
+	ETHTOOL_A_PAUSE_RX,				/* u8 */
+	ETHTOOL_A_PAUSE_TX,				/* u8 */
+
+	/* add new constants above here */
+	__ETHTOOL_A_PAUSE_CNT,
+	ETHTOOL_A_PAUSE_MAX = (__ETHTOOL_A_PAUSE_CNT - 1)
 };
 
 /* generic netlink info */

net/ethtool/Makefile

···
 
 ethtool_nl-y	:= netlink.o bitset.o strset.o linkinfo.o linkmodes.o \
 		   linkstate.o debug.o wol.o features.o privflags.o rings.o \
-		   channels.o coalesce.o
+		   channels.o coalesce.o pause.o

net/ethtool/netlink.c

···
 	[ETHTOOL_MSG_RINGS_GET]		= &ethnl_rings_request_ops,
 	[ETHTOOL_MSG_CHANNELS_GET]	= &ethnl_channels_request_ops,
 	[ETHTOOL_MSG_COALESCE_GET]	= &ethnl_coalesce_request_ops,
+	[ETHTOOL_MSG_PAUSE_GET]		= &ethnl_pause_request_ops,
 };
 
 static struct ethnl_dump_ctx *ethnl_dump_context(struct netlink_callback *cb)
···
 		.cmd	= ETHTOOL_MSG_COALESCE_SET,
 		.flags	= GENL_UNS_ADMIN_PERM,
 		.doit	= ethnl_set_coalesce,
+	},
+	{
+		.cmd	= ETHTOOL_MSG_PAUSE_GET,
+		.doit	= ethnl_default_doit,
+		.start	= ethnl_default_start,
+		.dumpit	= ethnl_default_dumpit,
+		.done	= ethnl_default_done,
 	},
 };
 

net/ethtool/netlink.h

···
 extern const struct ethnl_request_ops ethnl_rings_request_ops;
 extern const struct ethnl_request_ops ethnl_channels_request_ops;
 extern const struct ethnl_request_ops ethnl_coalesce_request_ops;
+extern const struct ethnl_request_ops ethnl_pause_request_ops;
 
 int ethnl_set_linkinfo(struct sk_buff *skb, struct genl_info *info);
 int ethnl_set_linkmodes(struct sk_buff *skb, struct genl_info *info);

net/ethtool/pause.c

···
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include "netlink.h"
+#include "common.h"
+
+struct pause_req_info {
+	struct ethnl_req_info		base;
+};
+
+struct pause_reply_data {
+	struct ethnl_reply_data		base;
+	struct ethtool_pauseparam	pauseparam;
+};
+
+#define PAUSE_REPDATA(__reply_base) \
+	container_of(__reply_base, struct pause_reply_data, base)
+
+static const struct nla_policy
+pause_get_policy[ETHTOOL_A_PAUSE_MAX + 1] = {
+	[ETHTOOL_A_PAUSE_UNSPEC]		= { .type = NLA_REJECT },
+	[ETHTOOL_A_PAUSE_HEADER]		= { .type = NLA_NESTED },
+	[ETHTOOL_A_PAUSE_AUTONEG]		= { .type = NLA_REJECT },
+	[ETHTOOL_A_PAUSE_RX]			= { .type = NLA_REJECT },
+	[ETHTOOL_A_PAUSE_TX]			= { .type = NLA_REJECT },
+};
+
+static int pause_prepare_data(const struct ethnl_req_info *req_base,
+			      struct ethnl_reply_data *reply_base,
+			      struct genl_info *info)
+{
+	struct pause_reply_data *data = PAUSE_REPDATA(reply_base);
+	struct net_device *dev = reply_base->dev;
+	int ret;
+
+	if (!dev->ethtool_ops->get_pauseparam)
+		return -EOPNOTSUPP;
+	ret = ethnl_ops_begin(dev);
+	if (ret < 0)
+		return ret;
+	dev->ethtool_ops->get_pauseparam(dev, &data->pauseparam);
+	ethnl_ops_complete(dev);
+
+	return 0;
+}
+
+static int pause_reply_size(const struct ethnl_req_info *req_base,
+			    const struct ethnl_reply_data *reply_base)
+{
+	return nla_total_size(sizeof(u8)) +	/* _PAUSE_AUTONEG */
+		nla_total_size(sizeof(u8)) +	/* _PAUSE_RX */
+		nla_total_size(sizeof(u8));	/* _PAUSE_TX */
+}
+
+static int pause_fill_reply(struct sk_buff *skb,
+			    const struct ethnl_req_info *req_base,
+			    const struct ethnl_reply_data *reply_base)
+{
+	const struct pause_reply_data *data = PAUSE_REPDATA(reply_base);
+	const struct ethtool_pauseparam *pauseparam = &data->pauseparam;
+
+	if (nla_put_u8(skb, ETHTOOL_A_PAUSE_AUTONEG, !!pauseparam->autoneg) ||
+	    nla_put_u8(skb, ETHTOOL_A_PAUSE_RX, !!pauseparam->rx_pause) ||
+	    nla_put_u8(skb, ETHTOOL_A_PAUSE_TX, !!pauseparam->tx_pause))
+		return -EMSGSIZE;
+
+	return 0;
+}
+
+const struct ethnl_request_ops ethnl_pause_request_ops = {
+	.request_cmd		= ETHTOOL_MSG_PAUSE_GET,
+	.reply_cmd		= ETHTOOL_MSG_PAUSE_GET_REPLY,
+	.hdr_attr		= ETHTOOL_A_PAUSE_HEADER,
+	.max_attr		= ETHTOOL_A_PAUSE_MAX,
+	.req_info_size		= sizeof(struct pause_req_info),
+	.reply_data_size	= sizeof(struct pause_reply_data),
+	.request_policy		= pause_get_policy,
+
+	.prepare_data		= pause_prepare_data,
+	.reply_size		= pause_reply_size,
+	.fill_reply		= pause_fill_reply,
+};