From 80917ec16fd22d239fca5b885983b3e7abf7c4de Mon Sep 17 00:00:00 2001
From: Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>
Date: Tue, 25 Feb 2020 09:42:35 +0100
Subject: [PATCH] net: Add preliminaly support for suspending/resuming a net
 interface

Such state needs to be set _from_ the PM API functions and not the other
way round. So if a network device driver does not support such API, it
will not be able to set the core net_if on PM state, obviously.

Currently, these functions only set/unset NET_IF_SUSPENDED flag.

More logic will be added later, to decide whether the net_if can be
actually set to suspend mode or not and also to take care of all timers
related to the interface.

Signed-off-by: Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>
---
 include/net/net_if.h   | 25 +++++++++++++++++++++++++
 subsys/net/Kconfig     |  7 +++++++
 subsys/net/ip/net_if.c | 31 ++++++++++++++++++++++++++++++-
 3 files changed, 62 insertions(+), 1 deletion(-)

diff --git a/include/net/net_if.h b/include/net/net_if.h
index c4b90d1b8da..c07379d164e 100644
--- a/include/net/net_if.h
+++ b/include/net/net_if.h
@@ -194,6 +194,9 @@ enum net_if_flag {
 	 */
 	NET_IF_NO_AUTO_START,
 
+	/** Power management specific: interface is being suspended */
+	NET_IF_SUSPENDED,
+
 /** @cond INTERNAL_HIDDEN */
 	/* Total number of flags - must be at the end of the enum */
 	NET_IF_NUM_FLAGS
@@ -2129,6 +2132,28 @@ static inline bool net_if_are_pending_tx_packets(struct net_if *iface)
 #endif
 }
 
+#ifdef CONFIG_NET_POWER_MANAGEMENT
+
+/**
+ * @brief Suspend a network interface from a power management perspective
+ *
+ * @param iface Pointer to network interface
+ *
+ * @return 0 on success, or -EALREADY/-EBUSY as possible errors.
+ */
+int net_if_suspend(struct net_if *iface);
+
+/**
+ * @brief Resume a network interface from a power management perspective
+ *
+ * @param iface Pointer to network interface
+ *
+ * @return 0 on success, or -EALREADY as a possible error.
+ */
+int net_if_resume(struct net_if *iface);
+
+#endif /* CONFIG_NET_POWER_MANAGEMENT */
+
 /** @cond INTERNAL_HIDDEN */
 struct net_if_api {
 	void (*init)(struct net_if *iface);
diff --git a/subsys/net/Kconfig b/subsys/net/Kconfig
index acbe27ba796..e0fde627eca 100644
--- a/subsys/net/Kconfig
+++ b/subsys/net/Kconfig
@@ -73,6 +73,13 @@ config NETWORKING
 
 if NETWORKING
 
+# Such option should not be configured manually but by device drivers
+# which supports PM properly.
+config NET_POWER_MANAGEMENT
+	bool
+	default n
+	depends on DEVICE_POWER_MANAGEMENT
+
 source "subsys/net/Kconfig.hostname"
 
 source "subsys/net/l2/Kconfig"
diff --git a/subsys/net/ip/net_if.c b/subsys/net/ip/net_if.c
index d54c7aac78f..c3afc166bdb 100644
--- a/subsys/net/ip/net_if.c
+++ b/subsys/net/ip/net_if.c
@@ -347,7 +347,8 @@ enum net_verdict net_if_send_data(struct net_if *iface, struct net_pkt *pkt)
 	enum net_verdict verdict = NET_OK;
 	int status = -EIO;
 
-	if (!net_if_flag_is_set(iface, NET_IF_UP)) {
+	if (!net_if_flag_is_set(iface, NET_IF_UP) ||
+	    net_if_flag_is_set(iface, NET_IF_SUSPENDED)) {
 		/* Drop packet if interface is not up */
 		NET_WARN("iface %p is down", iface);
 		verdict = NET_DROP;
@@ -3623,6 +3624,34 @@ bool net_if_is_promisc(struct net_if *iface)
 	return net_if_flag_is_set(iface, NET_IF_PROMISC);
 }
 
+#ifdef CONFIG_NET_POWER_MANAGEMENT
+
+int net_if_suspend(struct net_if *iface)
+{
+	if (net_if_are_pending_tx_packets(iface)) {
+		return -EBUSY;
+	}
+
+	if (net_if_flag_test_and_set(iface, NET_IF_SUSPENDED)) {
+		return -EALREADY;
+	}
+
+	return 0;
+}
+
+int net_if_resume(struct net_if *iface)
+{
+	if (!net_if_flag_is_set(iface, NET_IF_SUSPENDED)) {
+		return -EALREADY;
+	}
+
+	net_if_flag_clear(iface, NET_IF_SUSPENDED);
+
+	return 0;
+}
+
+#endif /* CONFIG_NET_POWER_MANAGEMENT */
+
 #if defined(CONFIG_NET_PKT_TIMESTAMP_THREAD)
 static void net_tx_ts_thread(void)
 {