10 files changed, 252 insertions, 20 deletions

diff --git a/Documentation/ABI/testing/sysfs-class-led b/Documentation/ABI/testing/sysfs-class-led
index 491cdeedc195..5f67f7ab277b 100644
--- a/Documentation/ABI/testing/sysfs-class-led
+++ b/Documentation/ABI/testing/sysfs-class-led
@@ -23,6 +23,23 @@ Description:
                 If the LED does not support different brightness levels, this
                 should be 1.
 
+What:           /sys/class/leds/<led>/brightness_hw_changed
+Date:           January 2017
+KernelVersion:  4.11
+Description:
+                Last hardware set brightness level for this LED. Some LEDs
+                may be changed autonomously by hardware/firmware. Only LEDs
+                where this happens and the driver can detect this, will have
+                this file.
+
+                This file supports poll() to detect when the hardware changes
+                the brightness.
+
+                Reading this file will return the last brightness level set
+                by the hardware, this may be different from the current
+                brightness. Reading this file when no hw brightness change
+                event has happened will return an ENODATA error.
+
 What:           /sys/class/leds/<led>/trigger
 Date:           March 2006
 KernelVersion:  2.6.17
diff --git a/Documentation/devicetree/bindings/leds/common.txt b/Documentation/devicetree/bindings/leds/common.txt
index 696be5792625..24b656014089 100644
--- a/Documentation/devicetree/bindings/leds/common.txt
+++ b/Documentation/devicetree/bindings/leds/common.txt
@@ -61,16 +61,24 @@ property can be omitted.
 
 Examples:
 
-system-status {
-        label = "Status";
-        linux,default-trigger = "heartbeat";
-        ...
+gpio-leds {
+        compatible = "gpio-leds";
+
+        system-status {
+                label = "Status";
+                linux,default-trigger = "heartbeat";
+                gpios = <&gpio0 0 GPIO_ACTIVE_HIGH>;
+        };
 };
 
-camera-flash {
-        label = "Flash";
-        led-sources = <0>, <1>;
-        led-max-microamp = <50000>;
-        flash-max-microamp = <320000>;
-        flash-max-timeout-us = <500000>;
+max77693-led {
+        compatible = "maxim,max77693-led";
+
+        camera-flash {
+                label = "Flash";
+                led-sources = <0>, <1>;
+                led-max-microamp = <50000>;
+                flash-max-microamp = <320000>;
+                flash-max-timeout-us = <500000>;
+        };
 };
diff --git a/Documentation/leds/leds-class.txt b/Documentation/leds/leds-class.txt
index f1f7ec9f5cc5..836cb16d6f09 100644
--- a/Documentation/leds/leds-class.txt
+++ b/Documentation/leds/leds-class.txt
@@ -65,6 +65,21 @@ LED subsystem core exposes following API for setting brightness:
                 blinking, returns -EBUSY if software blink fallback is enabled.
 
 
+LED registration API
+====================
+
+A driver wanting to register a LED classdev for use by other drivers /
+userspace needs to allocate and fill a led_classdev struct and then call
+[devm_]led_classdev_register. If the non devm version is used the driver
+must call led_classdev_unregister from its remove function before
+free-ing the led_classdev struct.
+
+If the driver can detect hardware initiated brightness changes and thus
+wants to have a brightness_hw_changed attribute then the LED_BRIGHT_HW_CHANGED
+flag must be set in flags before registering. Calling
+led_classdev_notify_brightness_hw_changed on a classdev not registered with
+the LED_BRIGHT_HW_CHANGED flag is a bug and will trigger a WARN_ON.
+
 Hardware accelerated blink of LEDs
 ==================================
 
diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index c621cbbb5768..275f467956ee 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -29,6 +29,15 @@ config LEDS_CLASS_FLASH
           for the flash related features of a LED device. It can be built
           as a module.
 
+config LEDS_BRIGHTNESS_HW_CHANGED
+        bool "LED Class brightness_hw_changed attribute support"
+        depends on LEDS_CLASS
+        help
+          This option enables support for the brightness_hw_changed attribute
+          for led sysfs class devices under /sys/class/leds.
+
+          See Documentation/ABI/testing/sysfs-class-led for details.
+
 comment "LED drivers"
 
 config LEDS_88PM860X
diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 326ee6e925a2..f2b0a80a62b4 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -103,6 +103,68 @@ static const struct attribute_group *led_groups[] = {
         NULL,
 };
 
+#ifdef CONFIG_LEDS_BRIGHTNESS_HW_CHANGED
+static ssize_t brightness_hw_changed_show(struct device *dev,
+                struct device_attribute *attr, char *buf)
+{
+        struct led_classdev *led_cdev = dev_get_drvdata(dev);
+
+        if (led_cdev->brightness_hw_changed == -1)
+                return -ENODATA;
+
+        return sprintf(buf, "%u\n", led_cdev->brightness_hw_changed);
+}
+
+static DEVICE_ATTR_RO(brightness_hw_changed);
+
+static int led_add_brightness_hw_changed(struct led_classdev *led_cdev)
+{
+        struct device *dev = led_cdev->dev;
+        int ret;
+
+        ret = device_create_file(dev, &dev_attr_brightness_hw_changed);
+        if (ret) {
+                dev_err(dev, "Error creating brightness_hw_changed\n");
+                return ret;
+        }
+
+        led_cdev->brightness_hw_changed_kn =
+                sysfs_get_dirent(dev->kobj.sd, "brightness_hw_changed");
+        if (!led_cdev->brightness_hw_changed_kn) {
+                dev_err(dev, "Error getting brightness_hw_changed kn\n");
+                device_remove_file(dev, &dev_attr_brightness_hw_changed);
+                return -ENXIO;
+        }
+
+        return 0;
+}
+
+static void led_remove_brightness_hw_changed(struct led_classdev *led_cdev)
+{
+        sysfs_put(led_cdev->brightness_hw_changed_kn);
+        device_remove_file(led_cdev->dev, &dev_attr_brightness_hw_changed);
+}
+
+void led_classdev_notify_brightness_hw_changed(struct led_classdev *led_cdev,
+                                               enum led_brightness brightness)
+{
+        if (WARN_ON(!led_cdev->brightness_hw_changed_kn))
+                return;
+
+        led_cdev->brightness_hw_changed = brightness;
+        sysfs_notify_dirent(led_cdev->brightness_hw_changed_kn);
+}
+EXPORT_SYMBOL_GPL(led_classdev_notify_brightness_hw_changed);
+#else
+static int led_add_brightness_hw_changed(struct led_classdev *led_cdev)
+{
+        return 0;
+}
+static void led_remove_brightness_hw_changed(struct led_classdev *led_cdev)
+{
+}
+#endif
+
 /**
  * led_classdev_suspend - suspend an led_classdev.
  * @led_cdev: the led_classdev to suspend.
@@ -204,10 +266,21 @@ int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
                 dev_warn(parent, "Led %s renamed to %s due to name collision",
                                 led_cdev->name, dev_name(led_cdev->dev));
 
+        if (led_cdev->flags & LED_BRIGHT_HW_CHANGED) {
+                ret = led_add_brightness_hw_changed(led_cdev);
+                if (ret) {
+                        device_unregister(led_cdev->dev);
+                        return ret;
+                }
+        }
+
         led_cdev->work_flags = 0;
 #ifdef CONFIG_LEDS_TRIGGERS
         init_rwsem(&led_cdev->trigger_lock);
 #endif
+#ifdef CONFIG_LEDS_BRIGHTNESS_HW_CHANGED
+        led_cdev->brightness_hw_changed = -1;
+#endif
         mutex_init(&led_cdev->led_access);
         /* add to the list of leds */
         down_write(&leds_list_lock);
@@ -256,6 +329,9 @@ void led_classdev_unregister(struct led_classdev *led_cdev)
 
         flush_work(&led_cdev->set_brightness_work);
 
+        if (led_cdev->flags & LED_BRIGHT_HW_CHANGED)
+                led_remove_brightness_hw_changed(led_cdev);
+
         device_unregister(led_cdev->dev);
 
         down_write(&leds_list_lock);
diff --git a/drivers/leds/leds-ktd2692.c b/drivers/leds/leds-ktd2692.c
index bf23ba191ad0..45296aaca9da 100644
--- a/drivers/leds/leds-ktd2692.c
+++ b/drivers/leds/leds-ktd2692.c
@@ -270,15 +270,15 @@ static int ktd2692_parse_dt(struct ktd2692_context *led, struct device *dev,
                 return -ENXIO;
 
         led->ctrl_gpio = devm_gpiod_get(dev, "ctrl", GPIOD_ASIS);
-        if (IS_ERR(led->ctrl_gpio)) {
-                ret = PTR_ERR(led->ctrl_gpio);
+        ret = PTR_ERR_OR_ZERO(led->ctrl_gpio);
+        if (ret) {
                 dev_err(dev, "cannot get ctrl-gpios %d\n", ret);
                 return ret;
         }
 
         led->aux_gpio = devm_gpiod_get(dev, "aux", GPIOD_ASIS);
-        if (IS_ERR(led->aux_gpio)) {
-                ret = PTR_ERR(led->aux_gpio);
+        ret = PTR_ERR_OR_ZERO(led->aux_gpio);
+        if (ret) {
                 dev_err(dev, "cannot get aux-gpios %d\n", ret);
                 return ret;
         }
diff --git a/drivers/leds/trigger/ledtrig-heartbeat.c b/drivers/leds/trigger/ledtrig-heartbeat.c
index c9f386213e9e..e6f2f8b9f09a 100644
--- a/drivers/leds/trigger/ledtrig-heartbeat.c
+++ b/drivers/leds/trigger/ledtrig-heartbeat.c
@@ -43,6 +43,9 @@ static void led_heartbeat_function(unsigned long data)
                 return;
         }
 
+        if (test_and_clear_bit(LED_BLINK_BRIGHTNESS_CHANGE, &led_cdev->work_flags))
+                led_cdev->blink_brightness = led_cdev->new_blink_brightness;
+
         /* acts like an actual heart beat -- ie thump-thump-pause... */
         switch (heartbeat_data->phase) {
         case 0:
@@ -59,26 +62,26 @@ static void led_heartbeat_function(unsigned long data)
                 delay = msecs_to_jiffies(70);
                 heartbeat_data->phase++;
                 if (!heartbeat_data->invert)
-                        brightness = led_cdev->max_brightness;
+                        brightness = led_cdev->blink_brightness;
                 break;
         case 1:
                 delay = heartbeat_data->period / 4 - msecs_to_jiffies(70);
                 heartbeat_data->phase++;
                 if (heartbeat_data->invert)
-                        brightness = led_cdev->max_brightness;
+                        brightness = led_cdev->blink_brightness;
                 break;
         case 2:
                 delay = msecs_to_jiffies(70);
                 heartbeat_data->phase++;
                 if (!heartbeat_data->invert)
-                        brightness = led_cdev->max_brightness;
+                        brightness = led_cdev->blink_brightness;
                 break;
         default:
                 delay = heartbeat_data->period - heartbeat_data->period / 4 -
                         msecs_to_jiffies(70);
                 heartbeat_data->phase = 0;
                 if (heartbeat_data->invert)
-                        brightness = led_cdev->max_brightness;
+                        brightness = led_cdev->blink_brightness;
                 break;
         }
 
@@ -133,7 +136,10 @@ static void heartbeat_trig_activate(struct led_classdev *led_cdev)
         setup_timer(&heartbeat_data->timer,
                     led_heartbeat_function, (unsigned long) led_cdev);
         heartbeat_data->phase = 0;
+        if (!led_cdev->blink_brightness)
+                led_cdev->blink_brightness = led_cdev->max_brightness;
         led_heartbeat_function(heartbeat_data->timer.data);
+        set_bit(LED_BLINK_SW, &led_cdev->work_flags);
         led_cdev->activated = true;
 }
 
@@ -145,6 +151,7 @@ static void heartbeat_trig_deactivate(struct led_classdev *led_cdev)
                 del_timer_sync(&heartbeat_data->timer);
                 device_remove_file(led_cdev->dev, &dev_attr_invert);
                 kfree(heartbeat_data);
+                clear_bit(LED_BLINK_SW, &led_cdev->work_flags);
                 led_cdev->activated = false;
         }
 }
diff --git a/include/linux/leds.h b/include/linux/leds.h
index 569cb531094c..38c0bd7ca107 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -13,6 +13,7 @@
 #define __LINUX_LEDS_H_INCLUDED
 
 #include <linux/device.h>
+#include <linux/kernfs.h>
 #include <linux/list.h>
 #include <linux/mutex.h>
 #include <linux/rwsem.h>
@@ -27,6 +28,7 @@ struct device;
 
 enum led_brightness {
         LED_OFF         = 0,
+        LED_ON          = 1,
         LED_HALF        = 127,
         LED_FULL        = 255,
 };
@@ -46,6 +48,7 @@ struct led_classdev {
 #define LED_DEV_CAP_FLASH       (1 << 18)
 #define LED_HW_PLUGGABLE        (1 << 19)
 #define LED_PANIC_INDICATOR     (1 << 20)
+#define LED_BRIGHT_HW_CHANGED   (1 << 21)
 
         /* set_brightness_work / blink_timer flags, atomic, private. */
         unsigned long           work_flags;
@@ -110,6 +113,11 @@ struct led_classdev {
         bool                    activated;
 #endif
 
+#ifdef CONFIG_LEDS_BRIGHTNESS_HW_CHANGED
+        int                      brightness_hw_changed;
+        struct kernfs_node      *brightness_hw_changed_kn;
+#endif
+
         /* Ensures consistent access to the LED Flash Class device */
         struct mutex            led_access;
 };
@@ -422,4 +430,12 @@ static inline void ledtrig_cpu(enum cpu_led_event evt)
 }
 #endif
 
+#ifdef CONFIG_LEDS_BRIGHTNESS_HW_CHANGED
+extern void led_classdev_notify_brightness_hw_changed(
+        struct led_classdev *led_cdev, enum led_brightness brightness);
+#else
+static inline void led_classdev_notify_brightness_hw_changed(
+        struct led_classdev *led_cdev, enum led_brightness brightness) { }
+#endif
+
 #endif          /* __LINUX_LEDS_H_INCLUDED */
diff --git a/tools/leds/Makefile b/tools/leds/Makefile
index c03a79ebf9c8..078b666fd78b 100644
--- a/tools/leds/Makefile
+++ b/tools/leds/Makefile
@@ -3,11 +3,11 @@
 CC = $(CROSS_COMPILE)gcc
 CFLAGS = -Wall -Wextra -g -I../../include/uapi
 
-all: uledmon
+all: uledmon led_hw_brightness_mon
 %: %.c
         $(CC) $(CFLAGS) -o $@ $^
 
 clean:
-        $(RM) uledmon
+        $(RM) uledmon led_hw_brightness_mon
 
 .PHONY: all clean
diff --git a/tools/leds/led_hw_brightness_mon.c b/tools/leds/led_hw_brightness_mon.c
new file mode 100644
index 000000000000..64642ccfe442
--- /dev/null
+++ b/tools/leds/led_hw_brightness_mon.c
@@ -0,0 +1,84 @@
+/*
+ * led_hw_brightness_mon.c
+ *
+ * This program monitors LED brightness level changes having its origin
+ * in hardware/firmware, i.e. outside of kernel control.
+ * A timestamp and brightness value is printed each time the brightness changes.
+ *
+ * Usage: led_hw_brightness_mon <device-name>
+ *
+ * <device-name> is the name of the LED class device to be monitored. Pressing
+ * CTRL+C will exit.
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <poll.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+
+#include <linux/uleds.h>
+
+int main(int argc, char const *argv[])
+{
+        int fd, ret;
+        char brightness_file_path[LED_MAX_NAME_SIZE + 11];
+        struct pollfd pollfd;
+        struct timespec ts;
+        char buf[11];
+
+        if (argc != 2) {
+                fprintf(stderr, "Requires <device-name> argument\n");
+                return 1;
+        }
+
+        snprintf(brightness_file_path, LED_MAX_NAME_SIZE,
+                 "/sys/class/leds/%s/brightness_hw_changed", argv[1]);
+
+        fd = open(brightness_file_path, O_RDONLY);
+        if (fd == -1) {
+                printf("Failed to open %s file\n", brightness_file_path);
+                return 1;
+        }
+
+        /*
+         * read may fail if no hw brightness change has occurred so far,
+         * but it is required to avoid spurious poll notifications in
+         * the opposite case.
+         */
+        read(fd, buf, sizeof(buf));
+
+        pollfd.fd = fd;
+        pollfd.events = POLLPRI;
+
+        while (1) {
+                ret = poll(&pollfd, 1, -1);
+                if (ret == -1) {
+                        printf("Failed to poll %s file (%d)\n",
+                                brightness_file_path, ret);
+                        ret = 1;
+                        break;
+                }
+
+                clock_gettime(CLOCK_MONOTONIC, &ts);
+
+                ret = read(fd, buf, sizeof(buf));
+                if (ret < 0)
+                        break;
+
+                ret = lseek(pollfd.fd, 0, SEEK_SET);
+                if (ret < 0) {
+                        printf("lseek failed (%d)\n", ret);
+                        break;
+                }
+
+                printf("[%ld.%09ld] %d\n", ts.tv_sec, ts.tv_nsec, atoi(buf));
+        }
+
+        close(fd);
+
+        return ret;
+}