linux-kernel - [PATCH 6/6] Bluetooth: Add MGMT command for controller capabilities

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Message-Id: <20200916131430.6.I5068c01cae3cea674a96e103a0cf4d8c81425a4f@changeid>
Date:   Wed, 16 Sep 2020 13:16:02 -0700
From:   Daniel Winkler <danielwinkler@...gle.com>
To:     linux-bluetooth@...r.kernel.org, marcel@...tmann.org
Cc:     chromeos-bluetooth-upstreaming@...omium.org,
        Daniel Winkler <danielwinkler@...gle.com>,
        Sonny Sasaka <sonnysasaka@...omium.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH 6/6] Bluetooth: Add MGMT command for controller capabilities

For advertising, we wish to know the LE tx power capabilities of the
controller in userspace, so this patch adds a new MGMT command to query
controller capabilities. The data returned is in TLV format, so it can
be easily used to convey any data determined to be useful in the future,
but for now it simply contains LE min and max tx power.

The change was tested by manually verifying that the new MGMT command
returns the tx power range as expected in userspace.

Reviewed-by: Sonny Sasaka <sonnysasaka@...omium.org>
Signed-off-by: Daniel Winkler <danielwinkler@...gle.com>
---

 include/net/bluetooth/mgmt.h |  9 +++++++++
 net/bluetooth/mgmt.c         | 39 ++++++++++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+)

diff --git a/include/net/bluetooth/mgmt.h b/include/net/bluetooth/mgmt.h
index db64cf4747554c..9aa792e5efc8d0 100644
--- a/include/net/bluetooth/mgmt.h
+++ b/include/net/bluetooth/mgmt.h
@@ -815,6 +815,15 @@ struct mgmt_rp_add_ext_adv_data {
 	__u8	instance;
 } __packed;
 
+#define MGMT_CAP_LE_TX_PWR_MIN	0x0000
+#define MGMT_CAP_LE_TX_PWR_MAX	0x0001
+
+#define MGMT_OP_READ_CONTROLLER_CAP	0x0056
+#define MGMT_OP_READ_CONTROLLER_CAP_SIZE	0
+struct mgmt_rp_read_controller_cap {
+	__u8     capabilities[0];
+} __packed;
+
 #define MGMT_EV_CMD_COMPLETE		0x0001
 struct mgmt_ev_cmd_complete {
 	__le16	opcode;
diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
index b9347ff1a1e961..d2e5bc4b3ddb8f 100644
--- a/net/bluetooth/mgmt.c
+++ b/net/bluetooth/mgmt.c
@@ -124,6 +124,7 @@ static const u16 mgmt_commands[] = {
 	MGMT_OP_REMOVE_ADV_MONITOR,
 	MGMT_OP_ADD_EXT_ADV_PARAMS,
 	MGMT_OP_ADD_EXT_ADV_DATA,
+	MGMT_OP_READ_CONTROLLER_CAP,
 };
 
 static const u16 mgmt_events[] = {
@@ -181,6 +182,7 @@ static const u16 mgmt_untrusted_commands[] = {
 	MGMT_OP_READ_EXP_FEATURES_INFO,
 	MGMT_OP_READ_DEF_SYSTEM_CONFIG,
 	MGMT_OP_READ_DEF_RUNTIME_CONFIG,
+	MGMT_OP_READ_CONTROLLER_CAP,
 };
 
 static const u16 mgmt_untrusted_events[] = {
@@ -4356,6 +4358,42 @@ static int remove_adv_monitor(struct sock *sk, struct hci_dev *hdev,
 	return err;
 }
 
+static int read_controller_cap(struct sock *sk, struct hci_dev *hdev,
+			       void *data, u16 len)
+{
+	u8 i = 0;
+
+	/* This command will return its data in TVL format. Currently we only
+	 * wish to include LE tx power parameters, so this struct can be given
+	 * a fixed size as data types are not changing.
+	 */
+	struct {
+		struct mgmt_tlv entry;
+		__s8 value;
+	} __packed cap[2];
+
+	BT_DBG("request for %s", hdev->name);
+	memset(cap, 0, sizeof(cap));
+
+	hci_dev_lock(hdev);
+
+	/* Append LE tx power bounds */
+	cap[i].entry.type = MGMT_CAP_LE_TX_PWR_MIN;
+	cap[i].entry.length = sizeof(__s8);
+	cap[i].value = hdev->min_le_tx_power;
+	i++;
+
+	cap[i].entry.type = MGMT_CAP_LE_TX_PWR_MAX;
+	cap[i].entry.length = sizeof(__s8);
+	cap[i].value = hdev->max_le_tx_power;
+	i++;
+
+	hci_dev_unlock(hdev);
+
+	return mgmt_cmd_complete(sk, hdev->id, MGMT_OP_READ_CONTROLLER_CAP,
+				 MGMT_STATUS_SUCCESS, cap, sizeof(cap));
+}
+
 static void read_local_oob_data_complete(struct hci_dev *hdev, u8 status,
 				         u16 opcode, struct sk_buff *skb)
 {
@@ -8208,6 +8246,7 @@ static const struct hci_mgmt_handler mgmt_handlers[] = {
 						HCI_MGMT_VAR_LEN },
 	{ add_ext_adv_data,        MGMT_ADD_EXT_ADV_DATA_SIZE,
 						HCI_MGMT_VAR_LEN },
+	{ read_controller_cap,     MGMT_OP_READ_CONTROLLER_CAP_SIZE },
 };
 
 void mgmt_index_added(struct hci_dev *hdev)
-- 
2.28.0.618.gf4bc123cb7-goog