From 4d63adfe12dd9cb61ed8badb4d798955399048c2 Mon Sep 17 00:00:00 2001
From: Mark Greer <mgreer@animalcreek.com>
Date: Thu, 15 Jun 2017 20:34:22 -0700
Subject: NFC: Add NFC_CMD_DEACTIVATE_TARGET support
Once an NFC target (i.e., a tag) is found, it remains active until
there is a failure reading or writing it (often caused by the target
moving out of range). While the target is active, the NFC adapter
and antenna must remain powered. This wastes power when the target
remains in range but the client application no longer cares whether
it is there or not.
To mitigate this, add a new netlink command that allows userspace
to deactivate an active target. When issued, this command will cause
the NFC subsystem to act as though the target was moved out of range.
Once the command has been executed, the client application can power
off the NFC adapter to reduce power consumption.
Signed-off-by: Mark Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
---
net/nfc/netlink.c | 29 +++++++++++++++++++++++++++++
1 file changed, 29 insertions(+)
(limited to 'net')
diff --git a/net/nfc/netlink.c b/net/nfc/netlink.c
index b251fb936a27..f6359c277212 100644
--- a/net/nfc/netlink.c
+++ b/net/nfc/netlink.c
@@ -928,6 +928,30 @@ static int nfc_genl_activate_target(struct sk_buff *skb, struct genl_info *info)
return rc;
}
+static int nfc_genl_deactivate_target(struct sk_buff *skb,
+ struct genl_info *info)
+{
+ struct nfc_dev *dev;
+ u32 device_idx, target_idx;
+ int rc;
+
+ if (!info->attrs[NFC_ATTR_DEVICE_INDEX])
+ return -EINVAL;
+
+ device_idx = nla_get_u32(info->attrs[NFC_ATTR_DEVICE_INDEX]);
+
+ dev = nfc_get_device(device_idx);
+ if (!dev)
+ return -ENODEV;
+
+ target_idx = nla_get_u32(info->attrs[NFC_ATTR_TARGET_INDEX]);
+
+ rc = nfc_deactivate_target(dev, target_idx, NFC_TARGET_MODE_SLEEP);
+
+ nfc_put_device(dev);
+ return rc;
+}
+
static int nfc_genl_dep_link_up(struct sk_buff *skb, struct genl_info *info)
{
struct nfc_dev *dev;
@@ -1751,6 +1775,11 @@ static const struct genl_ops nfc_genl_ops[] = {
.doit = nfc_genl_vendor_cmd,
.policy = nfc_genl_policy,
},
+ {
+ .cmd = NFC_CMD_DEACTIVATE_TARGET,
+ .doit = nfc_genl_deactivate_target,
+ .policy = nfc_genl_policy,
+ },
};
static struct genl_family nfc_genl_family __ro_after_init = {
--
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