There are multiple triggers implementing hardware control. However, the LED core doesn't really know the hardware control state since the coordination is done directly between the trigger and the LED device. Add an offloaded() callback so that the LED core can query the hardware control state. Signed-off-by: Rong Zhang --- Documentation/leds/leds-class.rst | 5 +++++ include/linux/leds.h | 1 + 2 files changed, 6 insertions(+) diff --git a/Documentation/leds/leds-class.rst b/Documentation/leds/leds-class.rst index 5db620ed27aa..84665200a88d 100644 --- a/Documentation/leds/leds-class.rst +++ b/Documentation/leds/leds-class.rst @@ -235,6 +235,11 @@ LED driver must implement the following API to support hw control: Returns a pointer to a struct device or NULL if nothing is currently attached. +LED trigger must implement the following API to support hw control: + - offloaded: + return a boolean indicating if the trigger is offloaded to + hardware. + LED driver can activate additional modes by default to workaround the impossibility of supporting each different mode on the supported trigger. Examples are hardcoding the blink speed to a set interval, enable special diff --git a/include/linux/leds.h b/include/linux/leds.h index b16b803cc1ac..7332034a43c8 100644 --- a/include/linux/leds.h +++ b/include/linux/leds.h @@ -485,6 +485,7 @@ struct led_trigger { const char *name; int (*activate)(struct led_classdev *led_cdev); void (*deactivate)(struct led_classdev *led_cdev); + bool (*offloaded)(struct led_classdev *led_cdev); /* Brightness set by led_trigger_event */ enum led_brightness brightness; -- 2.53.0 "chromeos-auto" is a private hardware control trigger which always stays in hardware control. Implement offloaded() callback with its return value to be always true to reflect this. Signed-off-by: Rong Zhang --- drivers/leds/leds-cros_ec.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/leds/leds-cros_ec.c b/drivers/leds/leds-cros_ec.c index bea3cc3fbfd2..f48e3cf6ccf6 100644 --- a/drivers/leds/leds-cros_ec.c +++ b/drivers/leds/leds-cros_ec.c @@ -86,12 +86,18 @@ static int cros_ec_led_trigger_activate(struct led_classdev *led_cdev) return cros_ec_led_send_cmd(priv->cros_ec, &arg); } +static bool cros_ec_led_trigger_offloaded(struct led_classdev *led_cdev) +{ + return true; +} + static struct led_hw_trigger_type cros_ec_led_trigger_type; static struct led_trigger cros_ec_led_trigger = { .name = "chromeos-auto", .trigger_type = &cros_ec_led_trigger_type, .activate = cros_ec_led_trigger_activate, + .offloaded = cros_ec_led_trigger_offloaded, }; static int cros_ec_led_brightness_set_blocking(struct led_classdev *led_cdev, -- 2.53.0 "omnia-mcu" is a private hardware control trigger which always stays in hardware control mode. Implement offloaded() callback with its return value to be always true to reflect this. Meanwhile, declare it as a hardware control trigger as it's forgotten before. Signed-off-by: Rong Zhang --- drivers/leds/leds-turris-omnia.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/leds/leds-turris-omnia.c b/drivers/leds/leds-turris-omnia.c index 25ee5c1eb820..8e016ca86403 100644 --- a/drivers/leds/leds-turris-omnia.c +++ b/drivers/leds/leds-turris-omnia.c @@ -195,10 +195,16 @@ static void omnia_hwtrig_deactivate(struct led_classdev *cdev) err); } +static bool omnia_hwtrig_offloaded(struct led_classdev *cdev) +{ + return true; +} + static struct led_trigger omnia_hw_trigger = { .name = "omnia-mcu", .activate = omnia_hwtrig_activate, .deactivate = omnia_hwtrig_deactivate, + .offloaded = omnia_hwtrig_offloaded, .trigger_type = &omnia_hw_trigger_type, }; @@ -251,6 +257,7 @@ static int omnia_led_register(struct i2c_client *client, struct omnia_led *led, * by LED class from the linux,default-trigger property. */ cdev->default_trigger = omnia_hw_trigger.name; + cdev->hw_control_trigger = omnia_hw_trigger.name; /* Put the LED into software mode */ ret = omnia_cmd_write_u8(client, OMNIA_CMD_LED_MODE, OMNIA_CMD_LED_MODE_LED(led->reg) | -- 2.53.0 "netdev" can run in hardware control according to hardware capabilities and trigger options. Implement offloaded() callback to provide its hardware control state to the LED core. Signed-off-by: Rong Zhang --- drivers/leds/trigger/ledtrig-netdev.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/leds/trigger/ledtrig-netdev.c b/drivers/leds/trigger/ledtrig-netdev.c index 64c078e997f2..a26109ca4b1c 100644 --- a/drivers/leds/trigger/ledtrig-netdev.c +++ b/drivers/leds/trigger/ledtrig-netdev.c @@ -754,10 +754,18 @@ static void netdev_trig_deactivate(struct led_classdev *led_cdev) kfree(trigger_data); } +static bool netdev_trig_offloaded(struct led_classdev *led_cdev) +{ + struct led_netdev_data *trigger_data = led_get_trigger_data(led_cdev); + + return trigger_data->hw_control; +} + static struct led_trigger netdev_led_trigger = { .name = "netdev", .activate = netdev_trig_activate, .deactivate = netdev_trig_deactivate, + .offloaded = netdev_trig_offloaded, .groups = netdev_trig_groups, }; -- 2.53.0 There are multiple triggers implementing hardware control. Only "netdev" provides a custom attribute to determine if it's offloaded to hardware (i.e., in hardware control). For other triggers, there is no obvious way for userspace to determine the trigger state programmatically. Moreover, userspace can't query if an LED device supports hardware control or identifies these triggers. Add a new attribute "trigger_may_offload" to the LED core, so that userspace can determine: - if the LED device supports hardware control (supported => visible) - which trigger is the hardware control trigger selected by the LED device - if the trigger is selected ("") - if the trigger is offloaded ("[foo_trigger]") Note: the documentation describes the attribute as "returning a list" despite the LED core currently only supports one hardware control trigger per LED device. This is intentional to make the attribute extensible in the future without breaking userspace. Signed-off-by: Rong Zhang --- .../ABI/obsolete/sysfs-class-led-trigger-netdev | 16 ++++++++ Documentation/ABI/testing/sysfs-class-led | 22 +++++++++++ .../ABI/testing/sysfs-class-led-trigger-netdev | 13 ------- Documentation/leds/leds-class.rst | 8 ++++ drivers/leds/led-class.c | 23 +++++++++++ drivers/leds/led-triggers.c | 45 ++++++++++++++++++++++ drivers/leds/leds.h | 2 + drivers/leds/trigger/ledtrig-netdev.c | 2 + 8 files changed, 118 insertions(+), 13 deletions(-) diff --git a/Documentation/ABI/obsolete/sysfs-class-led-trigger-netdev b/Documentation/ABI/obsolete/sysfs-class-led-trigger-netdev new file mode 100644 index 000000000000..8d2fbfaf50c3 --- /dev/null +++ b/Documentation/ABI/obsolete/sysfs-class-led-trigger-netdev @@ -0,0 +1,16 @@ +What: /sys/class/leds//offloaded +Date: June 2026 +KernelVersion: 7.3 +Contact: linux-leds@vger.kernel.org +Description: + Communicate whether the LED trigger modes are offloaded to + hardware or whether software fallback is used. + + If 0, the LED is using software fallback to blink. + + If 1, the LED blinking in requested mode is offloaded to + hardware. + + /sys/class/leds//trigger_may_offload provides a generic + method to query the offloaded state of supported triggers, + superseding this attribute. diff --git a/Documentation/ABI/testing/sysfs-class-led b/Documentation/ABI/testing/sysfs-class-led index 0313b82644f2..edd5a9a74dfd 100644 --- a/Documentation/ABI/testing/sysfs-class-led +++ b/Documentation/ABI/testing/sysfs-class-led @@ -78,6 +78,28 @@ Description: (which would often be configured in the device tree for the hardware). +What: /sys/class/leds//trigger_may_offload +Date: June 2026 +KernelVersion: 7.3 +Contact: linux-leds@vger.kernel.org +Description: + Names and states of triggers that may be offloaded to hardware. + Such triggers are also called "hw control trigger" in some + context. + + Only exists when the LED supports trigger offload. + + Reading this file returns a list of triggers that are capable to + be offloaded. The optional brackets around the trigger name + indicate the state of the current trigger: + + - `foo_trigger`: the trigger is not selected. + - ``: the trigger is selected, but falls back to + software blink for some reason (e.g., incompatible trigger + parameters) + - `[foo_trigger]`: the trigger is selected and offloaded to + hardware. + What: /sys/class/leds//inverted Date: January 2011 KernelVersion: 2.6.38 diff --git a/Documentation/ABI/testing/sysfs-class-led-trigger-netdev b/Documentation/ABI/testing/sysfs-class-led-trigger-netdev index ed46b37ab8a2..396d37a4b820 100644 --- a/Documentation/ABI/testing/sysfs-class-led-trigger-netdev +++ b/Documentation/ABI/testing/sysfs-class-led-trigger-netdev @@ -62,19 +62,6 @@ Description: When offloaded is true, the blink interval is controlled by hardware and won't reflect the value set in interval. -What: /sys/class/leds//offloaded -Date: Jun 2023 -KernelVersion: 6.5 -Contact: linux-leds@vger.kernel.org -Description: - Communicate whether the LED trigger modes are offloaded to - hardware or whether software fallback is used. - - If 0, the LED is using software fallback to blink. - - If 1, the LED blinking in requested mode is offloaded to - hardware. - What: /sys/class/leds//link_10 Date: Jun 2023 KernelVersion: 6.5 diff --git a/Documentation/leds/leds-class.rst b/Documentation/leds/leds-class.rst index 84665200a88d..41342ecb5f6b 100644 --- a/Documentation/leds/leds-class.rst +++ b/Documentation/leds/leds-class.rst @@ -179,6 +179,9 @@ ops and needs to declare specific support for the supported triggers. With hw control we refer to the LED driven by hardware. +A sysfs attribute `trigger_may_offload` is provided for userspace to +query supported triggers and their states. + LED driver must define the following value to support hw control: - hw_control_trigger: @@ -240,6 +243,11 @@ LED trigger must implement the following API to support hw control: return a boolean indicating if the trigger is offloaded to hardware. + If an LED driver specifies a hw control trigger but the + latter doesn't implement this callback, a dev_err_once will + be emitted and the LED trigger will be assumed to be not + offloaded. + LED driver can activate additional modes by default to workaround the impossibility of supporting each different mode on the supported trigger. Examples are hardcoding the blink speed to a set interval, enable special diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c index 9e14ae588f78..0ac80b93b8b5 100644 --- a/drivers/leds/led-class.c +++ b/drivers/leds/led-class.c @@ -90,8 +90,31 @@ static const struct bin_attribute *const led_trigger_bin_attrs[] = { &bin_attr_trigger, NULL, }; + +static DEVICE_ATTR(trigger_may_offload, 0444, led_trigger_may_offload_show, NULL); +static struct attribute *led_trigger_attrs[] = { + &dev_attr_trigger_may_offload.attr, + NULL, +}; + +static umode_t led_trigger_is_visible(struct kobject *kobj, + struct attribute *attr, + int idx) +{ + struct device *dev = kobj_to_dev(kobj); + struct led_classdev *led_cdev = dev_get_drvdata(dev); + + if (attr == &dev_attr_trigger_may_offload.attr && + !led_cdev->hw_control_trigger) + return 0; + + return attr->mode; +} + static const struct attribute_group led_trigger_group = { .bin_attrs = led_trigger_bin_attrs, + .attrs = led_trigger_attrs, + .is_visible = led_trigger_is_visible, }; #endif diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c index b1223218bda1..c43229d9c4c1 100644 --- a/drivers/leds/led-triggers.c +++ b/drivers/leds/led-triggers.c @@ -313,6 +313,51 @@ void led_trigger_set_default(struct led_classdev *led_cdev) } EXPORT_SYMBOL_GPL(led_trigger_set_default); +/* + * Caller must ensure led_cdev->trigger_lock held, + * and led_cdev->trigger->name must match led_cdev->hw_control_trigger. + */ +static bool led_trigger_get_offloaded(struct led_classdev *led_cdev) +{ + if (likely(led_cdev->trigger->offloaded)) + return led_cdev->trigger->offloaded(led_cdev); + + dev_err_once(led_cdev->dev, + "hw control trigger %s doesn't implement offloaded(), this is a bug\n", + led_cdev->trigger->name); + return false; +} + +ssize_t led_trigger_may_offload_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct led_classdev *led_cdev = dev_get_drvdata(dev); + bool hit, offloaded = false; + struct led_trigger *trig; + int len; + + mutex_lock(&led_cdev->led_access); + down_read(&led_cdev->trigger_lock); + + trig = led_cdev->trigger; + + hit = trig && !strcmp(led_cdev->hw_control_trigger, trig->name); + if (hit) + offloaded = led_trigger_get_offloaded(led_cdev); + + /* [offloaded] inactive */ + len = sysfs_emit(buf, "%s%s%s\n", + offloaded ? "[" : (hit ? "<" : ""), + led_cdev->hw_control_trigger, + offloaded ? "]" : (hit ? ">" : "")); + + up_read(&led_cdev->trigger_lock); + mutex_unlock(&led_cdev->led_access); + + return len; +} +EXPORT_SYMBOL_GPL(led_trigger_may_offload_show); + /* LED Trigger Interface */ int led_trigger_register(struct led_trigger *trig) diff --git a/drivers/leds/leds.h b/drivers/leds/leds.h index bee46651e068..9177e098989b 100644 --- a/drivers/leds/leds.h +++ b/drivers/leds/leds.h @@ -27,6 +27,8 @@ ssize_t led_trigger_read(struct file *filp, struct kobject *kobj, ssize_t led_trigger_write(struct file *filp, struct kobject *kobj, const struct bin_attribute *bin_attr, char *buf, loff_t pos, size_t count); +ssize_t led_trigger_may_offload_show(struct device *dev, + struct device_attribute *attr, char *buf); extern struct rw_semaphore leds_list_lock; extern struct list_head leds_list; diff --git a/drivers/leds/trigger/ledtrig-netdev.c b/drivers/leds/trigger/ledtrig-netdev.c index a26109ca4b1c..21f22eea4ab8 100644 --- a/drivers/leds/trigger/ledtrig-netdev.c +++ b/drivers/leds/trigger/ledtrig-netdev.c @@ -487,6 +487,8 @@ static ssize_t offloaded_show(struct device *dev, { struct led_netdev_data *trigger_data = led_trigger_get_drvdata(dev); + dev_warn_once(dev, "offloaded attribute has been deprecated, see trigger_may_offload.\n"); + return sprintf(buf, "%d\n", trigger_data->hw_control); } -- 2.53.0 Some hardware can autonomously activate/deactivate hardware control. After that, the LED hardware notifies the LED driver. Currently, there is no mechanism for LED drivers to notify the LED core about such events and initiate a trigger transition to reflect the hardware state. Add a new interface called led_trigger_notify_hw_control_changed(), so that LED drivers can call it to notify the LED core about the transition. The interface only allows two transitions: 1. "none" => private trigger 2. private trigger => "none" If the current trigger is neither the private trigger nor "none", no transition will be made. This protects the currently selected software trigger. Note that LED_OFF won't be emitted during the #2 transition, as some hardware may have selected a new brightness level during its hardware state transition (e.g., laptop keyboards with a shortcut cycling through different backlight brightnesses and auto mode). The interface is designed as a void function as any failure should be non-fatal and the result of transition should not have any impact on the LED drivers' event handling procedures. To use the interface, LEDS_TRIGGERS_HW_CHANGED must be enabled in Kconfig, and the LED driver must set the LED_TRIG_HW_CHANGED flag for the classdev. Signed-off-by: Rong Zhang --- Documentation/leds/leds-class.rst | 61 +++++++++++++++++++++++++++ drivers/leds/led-triggers.c | 86 +++++++++++++++++++++++++++++++++++++-- drivers/leds/trigger/Kconfig | 9 ++++ include/linux/leds.h | 8 ++++ 4 files changed, 161 insertions(+), 3 deletions(-) diff --git a/Documentation/leds/leds-class.rst b/Documentation/leds/leds-class.rst index 41342ecb5f6b..f250dc938e1f 100644 --- a/Documentation/leds/leds-class.rst +++ b/Documentation/leds/leds-class.rst @@ -261,9 +261,70 @@ the end use hw_control_set to activate hw control. A trigger can use hw_control_get to check if a LED is already in hw control and init their flags. +Alternatively, a private trigger can be implemented along with the LED driver if +the LED's hw control doesn't fit any generic trigger. To associate the private +trigger with the LED classdev, their `trigger_type` must be the same. The name +of the private trigger must be the same as `hw_control_trigger`. Since both the +LED classdev and the private trigger are in the same LED driver, it's not +necessary for them to coordinate via `hw_control_*` callbacks. + When the LED is in hw control, no software blink is possible and doing so will effectively disable hw control. +Hardware-initiated trigger transition +===================================== + +Some hardware can autonomously activate/deactivate hardware control. After that, +the LED hardware notifies the LED driver. + +If the driver can detect such transitions and thus wants to notify the LED core +to update the current trigger then the `LED_TRIG_HW_CHANGED` flag must be set in +flags before registering. To update the current trigger accordingly, call +`led_trigger_notify_hw_control_changed` on the LED classdev. Calling the method +on a classdev not registered with the `LED_TRIG_HW_CHANGED` flag or an +appropriate `hw_control_trigger` string is a bug and will trigger a WARN_ON. + +This capability is restricted to the LED device's private trigger. The private +trigger must have been properly registered (see above) and named after +`hw_control_trigger`, or else a dev_err() will be triggered. + +Only two transitions are defined: + +- "none" => private trigger: + This happens when the hardware autonomously activates hardware control + and when "none" (i.e., no trigger) is currently active. If the private + trigger is already active when the method is called, this is essentially + a no-op. + + The activation sequence for the private trigger will be executed as + normal. + + The LED driver and its private trigger must be able to handle the + activation sequence even if the hardware is currently in hardware + control. + + If error occurs in the activation sequence, the LED Trigger core reverts + the effective trigger to "none". + +- private trigger => "none" + This happens when the hardware autonomously deactivates hardware control + and when the private trigger is currently active. If "none" (i.e., no + trigger) is active when the method is called, this is essentially a + no-op. + + The deactivation sequence for the private trigger will be executed as + normal, except that the current LED brightness is retained. The reason + for keeping the brightness unchanged is that some hardware may choose a + specific brightness instead of simply turning off the LED after + autonomously deactivating hardware control. + + The LED driver and its private trigger must be able to handle the + deactivation sequence even if the hardware is not currently in hardware + control. + +If the current trigger is neither the private trigger nor "none", no transition +will be made. + Known Issues ============ diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c index c43229d9c4c1..73e9ce376d02 100644 --- a/drivers/leds/led-triggers.c +++ b/drivers/leds/led-triggers.c @@ -7,6 +7,7 @@ * Author: Richard Purdie */ +#include #include #include #include @@ -162,8 +163,8 @@ ssize_t led_trigger_read(struct file *filp, struct kobject *kobj, } EXPORT_SYMBOL_GPL(led_trigger_read); -/* Caller must ensure led_cdev->trigger_lock held */ -int led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trig) +static int __led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trig, + bool hw_triggered) { char *event = NULL; char *envp[2]; @@ -194,7 +195,21 @@ int led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trig) led_cdev->trigger_data = NULL; led_cdev->activated = false; led_cdev->flags &= ~LED_INIT_DEFAULT_TRIGGER; - led_set_brightness(led_cdev, LED_OFF); + + /* + * Hardware may have selected a new brightness level during its + * hardware control transition, so only reset brightness if we + * are switching to another trigger or if the switching is not + * hardware triggered. + * + * Note that this does not apply to the error path, as running + * into the error path implies a none => private trigger + * transition. This hints that the LED driver and its private + * trigger must have some fundamental bugs, so don't bother + * leaving the LED in an undefined state. + */ + if (trig || !hw_triggered) + led_set_brightness(led_cdev, LED_OFF); } if (trig) { spin_lock(&trig->leddev_list_lock); @@ -258,6 +273,12 @@ int led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trig) return ret; } + +/* Caller must ensure led_cdev->trigger_lock held */ +int led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trig) +{ + return __led_trigger_set(led_cdev, trig, false); +} EXPORT_SYMBOL_GPL(led_trigger_set); void led_trigger_remove(struct led_classdev *led_cdev) @@ -448,6 +469,65 @@ int devm_led_trigger_register(struct device *dev, } EXPORT_SYMBOL_GPL(devm_led_trigger_register); +#ifdef CONFIG_LEDS_TRIGGERS_HW_CHANGED +static void led_trigger_do_hw_control_transition(struct led_classdev *led_cdev, bool activate, + struct led_trigger *hc_trig) +{ + int err = 0; + + if (!led_cdev->trigger) { + /* "none" => private trigger. */ + if (activate) + err = __led_trigger_set(led_cdev, hc_trig, true); + } else if (led_cdev->trigger == hc_trig) { + /* private trigger => "none". */ + if (!activate) + err = __led_trigger_set(led_cdev, NULL, true); + } else { + /* Other trigger is active. */ + dev_dbg(led_cdev->dev, + "Ignoring hw control transition (%s %s) while %s is active", + activate ? "activate" : "deactivate", hc_trig->name, + led_cdev->trigger->name); + + return; + } + + if (err) + dev_warn(led_cdev->dev, "Failed to %s %s in hw control transition: %d", + activate ? "activate" : "deactivate", hc_trig->name, err); +} + +void led_trigger_notify_hw_control_changed(struct led_classdev *led_cdev, bool activate) +{ + struct led_trigger *trig; + + /* Restricted to private triggers. */ + if (WARN_ON(!(led_cdev->flags & LED_TRIG_HW_CHANGED) || + !led_cdev->hw_control_trigger || !led_cdev->trigger_type)) + return; + + down_read(&triggers_list_lock); + list_for_each_entry(trig, &trigger_list, next_trig) { + if (trig->trigger_type == led_cdev->trigger_type && + !strcmp(trig->name, led_cdev->hw_control_trigger)) { + down_write(&led_cdev->trigger_lock); + led_trigger_do_hw_control_transition(led_cdev, activate, trig); + up_write(&led_cdev->trigger_lock); + + up_read(&triggers_list_lock); + return; + } + } + up_read(&triggers_list_lock); + + dev_err(led_cdev->dev, + "%s() is called, but the private trigger (%s) is never registered\n", + __func__, led_cdev->hw_control_trigger); +} +EXPORT_SYMBOL_GPL(led_trigger_notify_hw_control_changed); +#endif /* CONFIG_LEDS_TRIGGERS_HW_CHANGED */ + /* Simple LED Trigger Interface */ void led_trigger_event(struct led_trigger *trig, diff --git a/drivers/leds/trigger/Kconfig b/drivers/leds/trigger/Kconfig index c11282a74b5a..798122154049 100644 --- a/drivers/leds/trigger/Kconfig +++ b/drivers/leds/trigger/Kconfig @@ -9,6 +9,15 @@ menuconfig LEDS_TRIGGERS if LEDS_TRIGGERS +config LEDS_TRIGGERS_HW_CHANGED + bool "LED hardware-initiated trigger transition support" + help + This option enables support for hardware initiated hardware control + transitions, where the LED hardware autonomously switches between + "none" (i.e., no trigger) and its private trigger. + + See Documentation/leds/leds-class.rst for details. + config LEDS_TRIGGER_TIMER tristate "LED Timer Trigger" help diff --git a/include/linux/leds.h b/include/linux/leds.h index 7332034a43c8..479391ddf5e5 100644 --- a/include/linux/leds.h +++ b/include/linux/leds.h @@ -109,6 +109,7 @@ struct led_classdev { #define LED_INIT_DEFAULT_TRIGGER BIT(23) #define LED_REJECT_NAME_CONFLICT BIT(24) #define LED_MULTI_COLOR BIT(25) +#define LED_TRIG_HW_CHANGED BIT(26) /* set_brightness_work / blink_timer flags, atomic, private. */ unsigned long work_flags; @@ -599,6 +600,13 @@ led_trigger_get_brightness(const struct led_trigger *trigger) #endif /* CONFIG_LEDS_TRIGGERS */ +#ifdef CONFIG_LEDS_TRIGGERS_HW_CHANGED +void led_trigger_notify_hw_control_changed(struct led_classdev *led_cdev, bool activate); +#else +static inline void led_trigger_notify_hw_control_changed(struct led_classdev *led_cdev, + bool activate) {} +#endif + /* Trigger specific enum */ enum led_trigger_netdev_modes { TRIGGER_NETDEV_LINK = 0, -- 2.53.0 Some recent models come with an ambient light sensor (ALS). On these models, their EC will automatically set the keyboard backlight to an appropriate brightness when the effective "hardware brightness" is 3. "Hardware brightness" can't be perfectly mapped to an LED classdev brightness, but the EC does use this predefined brightness value to represent auto mode. Currently, the code processing keyboard backlight is coupled with LED classdev, making it hard to expose the auto brightness (ALS) mode to the userspace. As the first step toward the goal, decouple hardware brightness from LED classdev brightness, and update comments about corresponding backlight modes. Since upcoming changes will heavily rely on kbd_bl.last_hw_brightness, also convert it into an atomic_t to prevent potential race conditions. To minimalize the diff set in upcoming changes, a trivial refactor also converts the initialization path into another equivalent form. Signed-off-by: Rong Zhang --- drivers/platform/x86/lenovo/Kconfig | 1 + drivers/platform/x86/lenovo/ideapad-laptop.c | 148 ++++++++++++++++++--------- 2 files changed, 103 insertions(+), 46 deletions(-) diff --git a/drivers/platform/x86/lenovo/Kconfig b/drivers/platform/x86/lenovo/Kconfig index 09b1b055d2e0..76ed1593e2aa 100644 --- a/drivers/platform/x86/lenovo/Kconfig +++ b/drivers/platform/x86/lenovo/Kconfig @@ -16,6 +16,7 @@ config IDEAPAD_LAPTOP select INPUT_SPARSEKMAP select NEW_LEDS select LEDS_CLASS + select LEDS_TRIGGERS help This is a driver for Lenovo IdeaPad netbooks contains drivers for rfkill switch, hotkey, fan control and backlight control. diff --git a/drivers/platform/x86/lenovo/ideapad-laptop.c b/drivers/platform/x86/lenovo/ideapad-laptop.c index 4fbc904f1fc3..40153dc9a5f2 100644 --- a/drivers/platform/x86/lenovo/ideapad-laptop.c +++ b/drivers/platform/x86/lenovo/ideapad-laptop.c @@ -9,6 +9,7 @@ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include +#include #include #include #include @@ -134,10 +135,31 @@ enum { }; /* - * These correspond to the number of supported states - 1 - * Future keyboard types may need a new system, if there's a collision - * KBD_BL_TRISTATE_AUTO has no way to report or set the auto state - * so it effectively has 3 states, but needs to handle 4 + * The enumeration has two purposes: + * - as an internal identifier for all known types of keyboard backlight + * - as a mandatory parameter of the KBLC command + * + * For each type, the hardware brightness values are defined as follows: + * +--------------------------+----------+-----+------+------+ + * | Hardware brightness | 0 | 1 | 2 | 3 | + * | Type | | | | | + * +--------------------------+----------+-----+------+------+ + * | KBD_BL_STANDARD | off | on | N/A | N/A | + * +--------------------------+----------+-----+------+------+ + * | KBD_BL_TRISTATE | off | low | high | N/A | + * +--------------------------+----------+-----+------+------+ + * | KBD_BL_TRISTATE_AUTO | off | low | high | auto | + * +--------------------------+----------+-----+------+------+ + * + * We map LED classdev brightness for KBD_BL_TRISTATE_AUTO as follows: + * +--------------------------+----------+-----+------+ + * | LED classdev brightness | 0 | 1 | 2 | + * | Operation | | | | + * +--------------------------+----------+-----+------+ + * | Read | off/auto | low | high | + * +--------------------------+----------+-----+------+ + * | Write | off | low | high | + * +--------------------------+----------+-----+------+ */ enum { KBD_BL_STANDARD = 1, @@ -145,6 +167,8 @@ enum { KBD_BL_TRISTATE_AUTO = 3, }; +#define KBD_BL_AUTO_MODE_HW_BRIGHTNESS 3 + #define KBD_BL_QUERY_TYPE 0x1 #define KBD_BL_TRISTATE_TYPE 0x5 #define KBD_BL_TRISTATE_AUTO_TYPE 0x7 @@ -203,7 +227,7 @@ struct ideapad_private { bool initialized; int type; struct led_classdev led; - unsigned int last_brightness; + atomic_t last_hw_brightness; } kbd_bl; struct { bool initialized; @@ -1592,7 +1616,24 @@ static int ideapad_kbd_bl_check_tristate(int type) return (type == KBD_BL_TRISTATE) || (type == KBD_BL_TRISTATE_AUTO); } -static int ideapad_kbd_bl_brightness_get(struct ideapad_private *priv) +static int ideapad_kbd_bl_brightness_parse(struct ideapad_private *priv, int hw_brightness) +{ + /* Off, low or high */ + if (hw_brightness <= priv->kbd_bl.led.max_brightness) + return hw_brightness; + + /* Auto (controlled by EC according to ALS), report as off */ + if (priv->kbd_bl.type == KBD_BL_TRISTATE_AUTO && + hw_brightness == KBD_BL_AUTO_MODE_HW_BRIGHTNESS) + return 0; + + /* Unknown value */ + dev_warn(&priv->platform_device->dev, + "Unknown keyboard backlight value: %u", hw_brightness); + return -EINVAL; +} + +static int ideapad_kbd_bl_hw_brightness_get(struct ideapad_private *priv) { unsigned long value; int err; @@ -1606,21 +1647,7 @@ static int ideapad_kbd_bl_brightness_get(struct ideapad_private *priv) if (err) return err; - /* Convert returned value to brightness level */ - value = FIELD_GET(KBD_BL_GET_BRIGHTNESS, value); - - /* Off, low or high */ - if (value <= priv->kbd_bl.led.max_brightness) - return value; - - /* Auto, report as off */ - if (value == priv->kbd_bl.led.max_brightness + 1) - return 0; - - /* Unknown value */ - dev_warn(&priv->platform_device->dev, - "Unknown keyboard backlight value: %lu", value); - return -EINVAL; + return FIELD_GET(KBD_BL_GET_BRIGHTNESS, value); } err = eval_hals(priv->adev->handle, &value); @@ -1630,6 +1657,16 @@ static int ideapad_kbd_bl_brightness_get(struct ideapad_private *priv) return !!test_bit(HALS_KBD_BL_STATE_BIT, &value); } +static int ideapad_kbd_bl_brightness_get(struct ideapad_private *priv) +{ + int hw_brightness = ideapad_kbd_bl_hw_brightness_get(priv); + + if (hw_brightness < 0) + return hw_brightness; + + return ideapad_kbd_bl_brightness_parse(priv, hw_brightness); +} + static enum led_brightness ideapad_kbd_bl_led_cdev_brightness_get(struct led_classdev *led_cdev) { struct ideapad_private *priv = container_of(led_cdev, struct ideapad_private, kbd_bl.led); @@ -1637,32 +1674,37 @@ static enum led_brightness ideapad_kbd_bl_led_cdev_brightness_get(struct led_cla return ideapad_kbd_bl_brightness_get(priv); } -static int ideapad_kbd_bl_brightness_set(struct ideapad_private *priv, unsigned int brightness) +static int ideapad_kbd_bl_hw_brightness_set(struct ideapad_private *priv, int hw_brightness) { - int err; unsigned long value; int type = priv->kbd_bl.type; + int err; if (ideapad_kbd_bl_check_tristate(type)) { - if (brightness > priv->kbd_bl.led.max_brightness) - return -EINVAL; - - value = FIELD_PREP(KBD_BL_SET_BRIGHTNESS, brightness) | + value = FIELD_PREP(KBD_BL_SET_BRIGHTNESS, hw_brightness) | FIELD_PREP(KBD_BL_COMMAND_TYPE, type) | KBD_BL_COMMAND_SET; err = exec_kblc(priv->adev->handle, value); } else { - err = exec_sals(priv->adev->handle, brightness ? SALS_KBD_BL_ON : SALS_KBD_BL_OFF); + value = hw_brightness ? SALS_KBD_BL_ON : SALS_KBD_BL_OFF; + err = exec_sals(priv->adev->handle, value); } - if (err) return err; - priv->kbd_bl.last_brightness = brightness; + atomic_set(&priv->kbd_bl.last_hw_brightness, hw_brightness); return 0; } +static int ideapad_kbd_bl_brightness_set(struct ideapad_private *priv, int brightness) +{ + if (brightness > priv->kbd_bl.led.max_brightness) + return -EINVAL; + + return ideapad_kbd_bl_hw_brightness_set(priv, brightness); +} + static int ideapad_kbd_bl_led_cdev_brightness_set(struct led_classdev *led_cdev, enum led_brightness brightness) { @@ -1673,26 +1715,31 @@ static int ideapad_kbd_bl_led_cdev_brightness_set(struct led_classdev *led_cdev, static void ideapad_kbd_bl_notify(struct ideapad_private *priv) { - int brightness; + int hw_brightness, brightness, last_brightness, last_hw_brightness; if (!priv->kbd_bl.initialized) return; - brightness = ideapad_kbd_bl_brightness_get(priv); - if (brightness < 0) + hw_brightness = ideapad_kbd_bl_hw_brightness_get(priv); + if (hw_brightness < 0) return; - if (brightness == priv->kbd_bl.last_brightness) - return; + brightness = ideapad_kbd_bl_brightness_parse(priv, hw_brightness); + if (brightness < 0) + return; /* Reject insane values early. */ - priv->kbd_bl.last_brightness = brightness; + last_hw_brightness = atomic_xchg(&priv->kbd_bl.last_hw_brightness, hw_brightness); + if (hw_brightness == last_hw_brightness) + return; - led_classdev_notify_brightness_hw_changed(&priv->kbd_bl.led, brightness); + last_brightness = ideapad_kbd_bl_brightness_parse(priv, last_hw_brightness); + if (last_brightness < 0 || brightness != last_brightness) + led_classdev_notify_brightness_hw_changed(&priv->kbd_bl.led, brightness); } static int ideapad_kbd_bl_init(struct ideapad_private *priv) { - int brightness, err; + int hw_brightness, err; if (!priv->features.kbd_bl) return -ENODEV; @@ -1700,21 +1747,30 @@ static int ideapad_kbd_bl_init(struct ideapad_private *priv) if (WARN_ON(priv->kbd_bl.initialized)) return -EEXIST; - if (ideapad_kbd_bl_check_tristate(priv->kbd_bl.type)) - priv->kbd_bl.led.max_brightness = 2; - else - priv->kbd_bl.led.max_brightness = 1; + hw_brightness = ideapad_kbd_bl_hw_brightness_get(priv); + if (hw_brightness < 0) + return hw_brightness; - brightness = ideapad_kbd_bl_brightness_get(priv); - if (brightness < 0) - return brightness; + atomic_set(&priv->kbd_bl.last_hw_brightness, hw_brightness); - priv->kbd_bl.last_brightness = brightness; priv->kbd_bl.led.name = "platform::" LED_FUNCTION_KBD_BACKLIGHT; priv->kbd_bl.led.brightness_get = ideapad_kbd_bl_led_cdev_brightness_get; priv->kbd_bl.led.brightness_set_blocking = ideapad_kbd_bl_led_cdev_brightness_set; priv->kbd_bl.led.flags = LED_BRIGHT_HW_CHANGED | LED_RETAIN_AT_SHUTDOWN; + switch (priv->kbd_bl.type) { + case KBD_BL_TRISTATE_AUTO: + case KBD_BL_TRISTATE: + priv->kbd_bl.led.max_brightness = 2; + break; + case KBD_BL_STANDARD: + priv->kbd_bl.led.max_brightness = 1; + break; + default: + /* This has already been validated by ideapad_check_features(). */ + unreachable(); + } + err = led_classdev_register(&priv->platform_device->dev, &priv->kbd_bl.led); if (err) return err; -- 2.53.0 ACPI notifications are delivered in dedicated work contexts and may arrive simultaneously. In the following change, much work will be done while handling the notification, which could lead to potential race conditions. Introduce a new mutex to serialize keyboard backlight notifications to prevent potential race conditions. Signed-off-by: Rong Zhang --- drivers/platform/x86/lenovo/ideapad-laptop.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/drivers/platform/x86/lenovo/ideapad-laptop.c b/drivers/platform/x86/lenovo/ideapad-laptop.c index 40153dc9a5f2..97949094ead4 100644 --- a/drivers/platform/x86/lenovo/ideapad-laptop.c +++ b/drivers/platform/x86/lenovo/ideapad-laptop.c @@ -26,7 +26,9 @@ #include #include #include +#include #include +#include #include #include #include @@ -228,6 +230,8 @@ struct ideapad_private { int type; struct led_classdev led; atomic_t last_hw_brightness; + + struct mutex notif_mutex; /* protects notifications */ } kbd_bl; struct { bool initialized; @@ -1720,6 +1724,8 @@ static void ideapad_kbd_bl_notify(struct ideapad_private *priv) if (!priv->kbd_bl.initialized) return; + guard(mutex)(&priv->kbd_bl.notif_mutex); + hw_brightness = ideapad_kbd_bl_hw_brightness_get(priv); if (hw_brightness < 0) return; @@ -1747,6 +1753,10 @@ static int ideapad_kbd_bl_init(struct ideapad_private *priv) if (WARN_ON(priv->kbd_bl.initialized)) return -EEXIST; + err = devm_mutex_init(&priv->platform_device->dev, &priv->kbd_bl.notif_mutex); + if (err) + return err; + hw_brightness = ideapad_kbd_bl_hw_brightness_get(priv); if (hw_brightness < 0) return hw_brightness; -- 2.53.0 Currently, the auto brightness mode of keyboard backlight maps to brightness=0 in LED classdev. The only method to switch to such a mode is by pressing the manufacturer-defined shortcut (Fn+Space). However, 0 is a multiplexed brightness value; writing 0 simply results in the backlight being turned off. With brightness processing code decoupled from LED classdev, we can now fully support the auto brightness mode. In this mode, the keyboard backlight is controlled by the EC according to the ambient light sensor (ALS). To utilize this, a private hardware control trigger "ideapad-auto" is added, with the event handling procedure calling the led_trigger_notify_hw_control_changed() interface to activate/deactivate the private trigger according to the current LED trigger state. Meanwhile, block brightness changes on exit to prevent the side effect of LED device unregistration when the private trigger is active from resetting the brightness to zero, so that we can retain the state of auto mode among boots. Signed-off-by: Rong Zhang --- drivers/platform/x86/lenovo/ideapad-laptop.c | 63 ++++++++++++++++++++++++++++ 1 file changed, 63 insertions(+) diff --git a/drivers/platform/x86/lenovo/ideapad-laptop.c b/drivers/platform/x86/lenovo/ideapad-laptop.c index 97949094ead4..a83af9bf843c 100644 --- a/drivers/platform/x86/lenovo/ideapad-laptop.c +++ b/drivers/platform/x86/lenovo/ideapad-laptop.c @@ -1714,9 +1714,56 @@ static int ideapad_kbd_bl_led_cdev_brightness_set(struct led_classdev *led_cdev, { struct ideapad_private *priv = container_of(led_cdev, struct ideapad_private, kbd_bl.led); + /* + * When deinitializing: It must be the side effect of led_cdev + * unregistration when our private trigger is active. We've set + * LED_RETAIN_AT_SHUTDOWN to retain led_cdev brightness level. + * To do the same for auto mode, gate changes and return early. + */ + if (unlikely(!priv->kbd_bl.initialized)) + return 0; + return ideapad_kbd_bl_brightness_set(priv, brightness); } +static bool ideapad_kbd_bl_auto_trigger_offloaded(struct led_classdev *led_cdev) +{ + struct ideapad_private *priv = container_of(led_cdev, struct ideapad_private, kbd_bl.led); + + return atomic_read(&priv->kbd_bl.last_hw_brightness) == KBD_BL_AUTO_MODE_HW_BRIGHTNESS; +} + +static int ideapad_kbd_bl_auto_trigger_activate(struct led_classdev *led_cdev) +{ + struct ideapad_private *priv = container_of(led_cdev, struct ideapad_private, kbd_bl.led); + + return ideapad_kbd_bl_hw_brightness_set(priv, KBD_BL_AUTO_MODE_HW_BRIGHTNESS); +} + +static struct led_hw_trigger_type ideapad_kbd_bl_auto_trigger_type; + +static struct led_trigger ideapad_kbd_bl_auto_trigger = { + .name = "ideapad-auto", + .trigger_type = &ideapad_kbd_bl_auto_trigger_type, + .activate = ideapad_kbd_bl_auto_trigger_activate, + .offloaded = ideapad_kbd_bl_auto_trigger_offloaded, +}; + +static void ideapad_kbd_bl_notify_hw_control(struct ideapad_private *priv, + int hw_brightness, int last_hw_brightness) +{ + bool hw_control, last_hw_control; + + if (priv->kbd_bl.type != KBD_BL_TRISTATE_AUTO) + return; + + hw_control = hw_brightness == KBD_BL_AUTO_MODE_HW_BRIGHTNESS; + last_hw_control = last_hw_brightness == KBD_BL_AUTO_MODE_HW_BRIGHTNESS; + + if (hw_control != last_hw_control) + led_trigger_notify_hw_control_changed(&priv->kbd_bl.led, hw_control); +} + static void ideapad_kbd_bl_notify(struct ideapad_private *priv) { int hw_brightness, brightness, last_brightness, last_hw_brightness; @@ -1738,6 +1785,8 @@ static void ideapad_kbd_bl_notify(struct ideapad_private *priv) if (hw_brightness == last_hw_brightness) return; + ideapad_kbd_bl_notify_hw_control(priv, hw_brightness, last_hw_brightness); + last_brightness = ideapad_kbd_bl_brightness_parse(priv, last_hw_brightness); if (last_brightness < 0 || brightness != last_brightness) led_classdev_notify_brightness_hw_changed(&priv->kbd_bl.led, brightness); @@ -1770,6 +1819,20 @@ static int ideapad_kbd_bl_init(struct ideapad_private *priv) switch (priv->kbd_bl.type) { case KBD_BL_TRISTATE_AUTO: + err = devm_led_trigger_register(&priv->platform_device->dev, + &ideapad_kbd_bl_auto_trigger); + if (err) + return err; + + priv->kbd_bl.led.flags |= LED_TRIG_HW_CHANGED; + priv->kbd_bl.led.hw_control_trigger = ideapad_kbd_bl_auto_trigger.name; + priv->kbd_bl.led.trigger_type = &ideapad_kbd_bl_auto_trigger_type; + + /* Hardware remembers the last brightness level, including auto mode. */ + if (hw_brightness == KBD_BL_AUTO_MODE_HW_BRIGHTNESS) + priv->kbd_bl.led.default_trigger = ideapad_kbd_bl_auto_trigger.name; + + fallthrough; case KBD_BL_TRISTATE: priv->kbd_bl.led.max_brightness = 2; break; -- 2.53.0