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[93.42.71.246]) by smtp.googlemail.com with ESMTPSA id bf8sm8537878edb.46.2021.11.07.16.25.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 07 Nov 2021 16:25:04 -0800 (PST) From: Ansuel Smith To: Andrew Lunn , Vivien Didelot , Florian Fainelli , Vladimir Oltean , "David S. Miller" , Jakub Kicinski , Rob Herring , Jonathan Corbet , Pavel Machek , Ansuel Smith , John Crispin , netdev@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-leds@vger.kernel.org Cc: =?UTF-8?q?Marek=20Beh=C3=BAn?= Subject: [RFC PATCH v2 1/5] leds: trigger: add API for HW offloading of triggers Date: Mon, 8 Nov 2021 01:24:56 +0100 Message-Id: <20211108002500.19115-2-ansuelsmth@gmail.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20211108002500.19115-1-ansuelsmth@gmail.com> References: <20211108002500.19115-1-ansuelsmth@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-leds@vger.kernel.org From: Marek Behún Add method trigger_offload() and member variable `offloaded` to struct led_classdev. Add helper functions led_trigger_offload() and led_trigger_offload_stop(). The trigger_offload() method, when implemented by the LED driver, should be called (via led_trigger_offload() function) from trigger code wanting to be offloaded at the moment when configuration of the trigger changes. If the trigger is successfully offloaded, this method returns 0 and the trigger does not have to blink the LED in software. If the trigger with given configuration cannot be offloaded, the method should return -EOPNOTSUPP, in which case the trigger must blink the LED in SW. The second argument to trigger_offload() being false means that the offloading is being disabled. In this case the function must return 0, errors are not permitted. An additional config CONFIG_LEDS_OFFLOAD_TRIGGERS is added to add support for these special trigger offload driven. Signed-off-by: Marek Behún Signed-off-by: Ansuel Smith --- Documentation/leds/leds-class.rst | 20 +++++++++++++++++++ drivers/leds/led-triggers.c | 1 + drivers/leds/trigger/Kconfig | 10 ++++++++++ include/linux/leds.h | 33 +++++++++++++++++++++++++++++++ 4 files changed, 64 insertions(+) diff --git a/Documentation/leds/leds-class.rst b/Documentation/leds/leds-class.rst index cd155ead8703..5bf6e5d471ce 100644 --- a/Documentation/leds/leds-class.rst +++ b/Documentation/leds/leds-class.rst @@ -169,6 +169,26 @@ Setting the brightness to zero with brightness_set() callback function should completely turn off the LED and cancel the previously programmed hardware blinking function, if any. +Hardware offloading of LED triggers +=================================== + +Some LEDs can be driven by hardware triggers (for example a LED connected to +an ethernet PHY or an ethernet switch can be configured to blink on activity on +the network, which in software is done by the netdev trigger). + +To do such offloading, LED driver must support this and a deficated offload +trigger must be used. The LED must implement the trigger_offload() method and +the trigger code must try to call this method (via led_trigger_offload() +function) to set the LED to this particular mode. (and disable any software +blinking) + +The implementation of the trigger_offload() method by the LED driver must return +0 if the offload is successful and -EOPNOTSUPP if the requested trigger +configuration is not supported. + +If the second argument (enable) to the trigger_offload() method is false, any +active HW offloading must be deactivated. In this case errors are not permitted +in the trigger_offload() method and the driver will be set to the new trigger. Known Issues ============ diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c index 072491d3e17b..281c52914f42 100644 --- a/drivers/leds/led-triggers.c +++ b/drivers/leds/led-triggers.c @@ -179,6 +179,7 @@ int led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trig) cancel_work_sync(&led_cdev->set_brightness_work); led_stop_software_blink(led_cdev); + led_trigger_offload_stop(led_cdev); if (led_cdev->trigger->deactivate) led_cdev->trigger->deactivate(led_cdev); device_remove_groups(led_cdev->dev, led_cdev->trigger->groups); diff --git a/drivers/leds/trigger/Kconfig b/drivers/leds/trigger/Kconfig index dc6816d36d06..33aba8defeab 100644 --- a/drivers/leds/trigger/Kconfig +++ b/drivers/leds/trigger/Kconfig @@ -9,6 +9,16 @@ menuconfig LEDS_TRIGGERS if LEDS_TRIGGERS +config LEDS_OFFLOAD_TRIGGERS + bool "LED Offload Trigger support" + help + This option enabled offload triggers support used by leds that + can be driven in hardware by declaring some specific triggers. + A offload trigger will expose a sysfs dir to configure the + different blinking trigger and the available hardware triggers. + + If unsure, say Y. + config LEDS_TRIGGER_TIMER tristate "LED Timer Trigger" help diff --git a/include/linux/leds.h b/include/linux/leds.h index ba4861ec73d3..949ab461287f 100644 --- a/include/linux/leds.h +++ b/include/linux/leds.h @@ -154,6 +154,13 @@ struct led_classdev { /* LEDs that have private triggers have this set */ struct led_hw_trigger_type *trigger_type; + +#ifdef CONFIG_LEDS_OFFLOAD_TRIGGERS + int offloaded; + /* some LEDs cne be driven by HW */ + int (*trigger_offload)(struct led_classdev *led_cdev, + bool enable); +#endif #endif #ifdef CONFIG_LEDS_BRIGHTNESS_HW_CHANGED @@ -409,6 +416,32 @@ static inline void *led_get_trigger_data(struct led_classdev *led_cdev) return led_cdev->trigger_data; } +#ifdef CONFIG_LEDS_OFFLOAD_TRIGGERS +static inline int led_trigger_offload(struct led_classdev *led_cdev) +{ + int ret; + + if (!led_cdev->trigger_offload) + return -EOPNOTSUPP; + + ret = led_cdev->trigger_offload(led_cdev, true); + led_cdev->offloaded = !ret; + + return ret; +} + +static inline void led_trigger_offload_stop(struct led_classdev *led_cdev) +{ + if (!led_cdev->trigger_offload) + return; + + if (led_cdev->offloaded) { + led_cdev->trigger_offload(led_cdev, false); + led_cdev->offloaded = false; + } +} +#endif + /** * led_trigger_rename_static - rename a trigger * @name: the new trigger name -- 2.32.0