nl80211: add power save commands

The most needed command from nl80211, which Wireless Extensions had,
is support for power save mode. Add a simple command to make it possible
to enable and disable power save via nl80211.

I was also planning about extending the interface, for example adding the
timeout value, but after thinking more about this I decided not to do it.
Basically there were three reasons:

Firstly, the parameters for power save are very much hardware dependent.
Trying to find a unified interface which would work with all hardware, and
still make sense to users, will be very difficult.

Secondly, IEEE 802.11 power save implementation in Linux is still in state
of flux. We have a long way to still to go and there is no way to predict
what kind of implementation we will have after few years. And because we
need to support nl80211 interface a long time, practically forever, adding
now parameters to nl80211 might create maintenance problems later on.

Third issue are the users. Power save parameters are mostly used for
debugging, so debugfs is better, more flexible, interface for this.
For example, wpa_supplicant currently doesn't configure anything related
to power save mode. It's better to strive that kernel can automatically
optimise the power save parameters, like with help of pm qos network
and other traffic parameters.

Later on, when we have better understanding of power save, we can extend
this command with more features, if there's a need for that.

Signed-off-by: Kalle Valo <kalle.valo@nokia.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 131 insertions, 0 deletions

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 328112081358..b0495a1da22e 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -148,6 +148,7 @@ static struct nla_policy nl80211_policy[NL80211_ATTR_MAX+1] __read_mostly = {
         [NL80211_ATTR_FRAME] = { .type = NLA_BINARY,
                                  .len = IEEE80211_MAX_DATA_LEN },
         [NL80211_ATTR_FRAME_MATCH] = { .type = NLA_BINARY, },
+        [NL80211_ATTR_PS_STATE] = { .type = NLA_U32 },
 };
 
 /* policy for the attributes */
@@ -4663,6 +4664,124 @@ unlock_rtnl:
         return err;
 }
 
+static int nl80211_set_power_save(struct sk_buff *skb, struct genl_info *info)
+{
+        struct cfg80211_registered_device *rdev;
+        struct wireless_dev *wdev;
+        struct net_device *dev;
+        u8 ps_state;
+        bool state;
+        int err;
+
+        if (!info->attrs[NL80211_ATTR_PS_STATE]) {
+                err = -EINVAL;
+                goto out;
+        }
+
+        ps_state = nla_get_u32(info->attrs[NL80211_ATTR_PS_STATE]);
+
+        if (ps_state != NL80211_PS_DISABLED && ps_state != NL80211_PS_ENABLED) {
+                err = -EINVAL;
+                goto out;
+        }
+
+        rtnl_lock();
+
+        err = get_rdev_dev_by_info_ifindex(info, &rdev, &dev);
+        if (err)
+                goto unlock_rdev;
+
+        wdev = dev->ieee80211_ptr;
+
+        if (!rdev->ops->set_power_mgmt) {
+                err = -EOPNOTSUPP;
+                goto unlock_rdev;
+        }
+
+        state = (ps_state == NL80211_PS_ENABLED) ? true : false;
+
+        if (state == wdev->ps)
+                goto unlock_rdev;
+
+        wdev->ps = state;
+
+        if (rdev->ops->set_power_mgmt(wdev->wiphy, dev, wdev->ps,
+                                      wdev->ps_timeout))
+                /* assume this means it's off */
+                wdev->ps = false;
+
+unlock_rdev:
+        cfg80211_unlock_rdev(rdev);
+        dev_put(dev);
+        rtnl_unlock();
+
+out:
+        return err;
+}
+
+static int nl80211_get_power_save(struct sk_buff *skb, struct genl_info *info)
+{
+        struct cfg80211_registered_device *rdev;
+        enum nl80211_ps_state ps_state;
+        struct wireless_dev *wdev;
+        struct net_device *dev;
+        struct sk_buff *msg;
+        void *hdr;
+        int err;
+
+        rtnl_lock();
+
+        err = get_rdev_dev_by_info_ifindex(info, &rdev, &dev);
+        if (err)
+                goto unlock_rtnl;
+
+        wdev = dev->ieee80211_ptr;
+
+        if (!rdev->ops->set_power_mgmt) {
+                err = -EOPNOTSUPP;
+                goto out;
+        }
+
+        msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+        if (!msg) {
+                err = -ENOMEM;
+                goto out;
+        }
+
+        hdr = nl80211hdr_put(msg, info->snd_pid, info->snd_seq, 0,
+                             NL80211_CMD_GET_POWER_SAVE);
+        if (!hdr) {
+                err = -ENOMEM;
+                goto free_msg;
+        }
+
+        if (wdev->ps)
+                ps_state = NL80211_PS_ENABLED;
+        else
+                ps_state = NL80211_PS_DISABLED;
+
+        NLA_PUT_U32(msg, NL80211_ATTR_PS_STATE, ps_state);
+
+        genlmsg_end(msg, hdr);
+        err = genlmsg_reply(msg, info);
+        goto out;
+
+nla_put_failure:
+        err = -ENOBUFS;
+
+free_msg:
+        nlmsg_free(msg);
+
+out:
+        cfg80211_unlock_rdev(rdev);
+        dev_put(dev);
+
+unlock_rtnl:
+        rtnl_unlock();
+
+        return err;
+}
+
 static struct genl_ops nl80211_ops[] = {
         {
                 .cmd = NL80211_CMD_GET_WIPHY,
@@ -4955,6 +5074,18 @@ static struct genl_ops nl80211_ops[] = {
                 .policy = nl80211_policy,
                 .flags = GENL_ADMIN_PERM,
         },
+        {
+                .cmd = NL80211_CMD_SET_POWER_SAVE,
+                .doit = nl80211_set_power_save,
+                .policy = nl80211_policy,
+                .flags = GENL_ADMIN_PERM,
+        },
+        {
+                .cmd = NL80211_CMD_GET_POWER_SAVE,
+                .doit = nl80211_get_power_save,
+                .policy = nl80211_policy,
+                /* can be retrieved by unprivileged users */
+        },
 };
 
 static struct genl_multicast_group nl80211_mlme_mcgrp = {