[PATCH v2] bluetooth: core: RfC - add basic LED triggers

[Heiner Kallweit <hkallweit1@gmail.com>]

In the bluetooth subsystem I miss the option to use LEDs to indicate
the status. This patch is based on the LED triggers in mac80211 and
adds two basic LED triggers (powered up, device connected) plus
a config option to enable the BT LED triggers.

It works fine on my system however I don't know the bluetooth stack
in too much detail and therefore appreciate any comment.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
v2:
- completely rewrote the code to be as generic as possible and minimize
  the changes to struct hci_dev
- make the details of the LED triggers opaque to struct hci_dev
- avoid using ifdef CONFIG_BT_LEDS in hci_core.h
- start with the radio trigger only
- factor out the generic basic led trigger code to facilitate adding
  further basic LED triggers
- fix indentation in Kconfig
- rename led.[ch] to leds.[ch]
---
 include/net/bluetooth/hci_core.h |  3 ++
 net/bluetooth/Kconfig            |  9 ++++
 net/bluetooth/Makefile           |  1 +
 net/bluetooth/hci_core.c         |  8 ++++
 net/bluetooth/leds.c             | 99 ++++++++++++++++++++++++++++++++++++++++
 net/bluetooth/leds.h             | 17 +++++++
 6 files changed, 137 insertions(+)
 create mode 100644 net/bluetooth/leds.c
 create mode 100644 net/bluetooth/leds.h

diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index c95e032..4ffec8b 100644
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -25,6 +25,7 @@
 #ifndef __HCI_CORE_H
 #define __HCI_CORE_H
 
+#include <linux/leds.h>
 #include <net/bluetooth/hci.h>
 #include <net/bluetooth/hci_sock.h>
 
@@ -395,6 +396,8 @@ struct hci_dev {
 	struct delayed_work	rpa_expired;
 	bdaddr_t		rpa;
 
+	struct led_trigger *radio_led;
+
 	int (*open)(struct hci_dev *hdev);
 	int (*close)(struct hci_dev *hdev);
 	int (*flush)(struct hci_dev *hdev);
diff --git a/net/bluetooth/Kconfig b/net/bluetooth/Kconfig
index 95d1a66..06c31b9 100644
--- a/net/bluetooth/Kconfig
+++ b/net/bluetooth/Kconfig
@@ -69,6 +69,15 @@ config BT_6LOWPAN
 	help
 	  IPv6 compression over Bluetooth Low Energy.
 
+config BT_LEDS
+	bool "Enable LED triggers"
+	depends on BT
+	depends on LEDS_CLASS
+	select LEDS_TRIGGERS
+	help
+	  This option selects a few LED triggers for different
+	  Bluetooth events.
+
 config BT_SELFTEST
 	bool "Bluetooth self testing support"
 	depends on BT && DEBUG_KERNEL
diff --git a/net/bluetooth/Makefile b/net/bluetooth/Makefile
index 2b15ae8..b3ff12e 100644
--- a/net/bluetooth/Makefile
+++ b/net/bluetooth/Makefile
@@ -17,6 +17,7 @@ bluetooth-y := af_bluetooth.o hci_core.o hci_conn.o hci_event.o mgmt.o \
 
 bluetooth-$(CONFIG_BT_BREDR) += sco.o
 bluetooth-$(CONFIG_BT_HS) += a2mp.o amp.o
+bluetooth-$(CONFIG_BT_LEDS) += leds.o
 bluetooth-$(CONFIG_BT_DEBUGFS) += hci_debugfs.o
 bluetooth-$(CONFIG_BT_SELFTEST) += selftest.o
 
diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 47bcef7..f472b1d 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -40,6 +40,7 @@
 #include "hci_request.h"
 #include "hci_debugfs.h"
 #include "smp.h"
+#include "leds.h"
 
 static void hci_rx_work(struct work_struct *work);
 static void hci_cmd_work(struct work_struct *work);
@@ -1395,6 +1396,7 @@ static int hci_dev_do_open(struct hci_dev *hdev)
 		hci_dev_set_flag(hdev, HCI_RPA_EXPIRED);
 		set_bit(HCI_UP, &hdev->flags);
 		hci_sock_dev_event(hdev, HCI_DEV_UP);
+		hci_led_radio(hdev, true);
 		if (!hci_dev_test_flag(hdev, HCI_SETUP) &&
 		    !hci_dev_test_flag(hdev, HCI_CONFIG) &&
 		    !hci_dev_test_flag(hdev, HCI_UNCONFIGURED) &&
@@ -1532,6 +1534,8 @@ int hci_dev_do_close(struct hci_dev *hdev)
 		return 0;
 	}
 
+	hci_led_radio(hdev, false);
+
 	/* Flush RX and TX works */
 	flush_work(&hdev->tx_work);
 	flush_work(&hdev->rx_work);
@@ -3067,6 +3071,8 @@ int hci_register_dev(struct hci_dev *hdev)
 	if (error < 0)
 		goto err_wqueue;
 
+	hci_led_init(hdev);
+
 	hdev->rfkill = rfkill_alloc(hdev->name, &hdev->dev,
 				    RFKILL_TYPE_BLUETOOTH, &hci_rfkill_ops,
 				    hdev);
@@ -3128,6 +3134,8 @@ void hci_unregister_dev(struct hci_dev *hdev)
 
 	id = hdev->id;
 
+	hci_led_exit(hdev);
+
 	write_lock(&hci_dev_list_lock);
 	list_del(&hdev->list);
 	write_unlock(&hci_dev_list_lock);
diff --git a/net/bluetooth/leds.c b/net/bluetooth/leds.c
new file mode 100644
index 0000000..377f643
--- /dev/null
+++ b/net/bluetooth/leds.c
@@ -0,0 +1,99 @@
+/*
+ * Copyright 2015, Heiner Kallweit <hkallweit1@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <net/bluetooth/bluetooth.h>
+#include <net/bluetooth/hci_core.h>
+
+#include "leds.h"
+
+struct hci_basic_led_trigger {
+	struct led_trigger	led_trigger;
+	atomic_t		cnt;
+};
+
+#define to_hci_basic_led_trigger(arg) container_of(arg, \
+					struct hci_basic_led_trigger, \
+					led_trigger)
+
+static void hci_basic_led(struct led_trigger *trig, bool inc)
+{
+	struct hci_basic_led_trigger *htrig;
+	int cnt;
+
+	if (!trig)
+		return;
+
+	htrig = to_hci_basic_led_trigger(trig);
+
+	if (inc)
+		cnt = atomic_inc_return(&htrig->cnt);
+	else
+		cnt = atomic_dec_return(&htrig->cnt);
+
+	WARN_ON(cnt < 0);
+
+	led_trigger_event(trig, cnt ? LED_FULL : LED_OFF);
+}
+
+void hci_led_radio(struct hci_dev *hdev, bool enabled)
+{
+	hci_basic_led(hdev->radio_led, enabled);
+}
+
+static void hci_basic_led_activate(struct led_classdev *led_cdev)
+{
+	struct hci_basic_led_trigger *htrig;
+	int cnt;
+
+	htrig = to_hci_basic_led_trigger(led_cdev->trigger);
+	cnt = atomic_read(&htrig->cnt);
+
+	led_trigger_event(led_cdev->trigger, cnt ? LED_FULL : LED_OFF);
+}
+
+static struct led_trigger *hci_basic_led_allocate(struct hci_dev *hdev,
+						  const char *name)
+{
+	struct hci_basic_led_trigger *htrig;
+
+	htrig =	devm_kzalloc(&hdev->dev, sizeof(*htrig), GFP_KERNEL);
+	if (!htrig)
+		return NULL;
+
+	atomic_set(&htrig->cnt, 0);
+	htrig->led_trigger.activate = hci_basic_led_activate;
+	htrig->led_trigger.name = devm_kasprintf(&hdev->dev, GFP_KERNEL,
+						 "%s-%s", hdev->name,
+						 name);
+	if (!htrig->led_trigger.name)
+		goto err_alloc;
+
+	if (led_trigger_register(&htrig->led_trigger))
+		goto err_register;
+
+	return &htrig->led_trigger;
+
+err_register:
+	devm_kfree(&hdev->dev, (void *)htrig->led_trigger.name);
+err_alloc:
+	devm_kfree(&hdev->dev, htrig);
+	return NULL;
+}
+
+void hci_led_init(struct hci_dev *hdev)
+{
+	/* initialize radio_led */
+	hdev->radio_led = hci_basic_led_allocate(hdev, "radio");
+}
+
+void hci_led_exit(struct hci_dev *hdev)
+{
+	if (hdev->radio_led)
+		led_trigger_unregister(hdev->radio_led);
+}
+
diff --git a/net/bluetooth/leds.h b/net/bluetooth/leds.h
new file mode 100644
index 0000000..7578cab
--- /dev/null
+++ b/net/bluetooth/leds.h
@@ -0,0 +1,17 @@
+/*
+ * Copyright 2015, Heiner Kallweit <hkallweit1@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifdef CONFIG_BT_LEDS
+void hci_led_radio(struct hci_dev *hdev, bool enabled);
+void hci_led_init(struct hci_dev *hdev);
+void hci_led_exit(struct hci_dev *hdev);
+#else
+static inline void hci_led_radio(struct hci_dev *hdev, bool enabled) {}
+static inline void hci_led_init(struct hci_dev *hdev) {}
+static inline void hci_led_exit(struct hci_dev *hdev) {}
+#endif
-- 
2.6.4