Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753831AbYKYQ5g (ORCPT ); Tue, 25 Nov 2008 11:57:36 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752447AbYKYQ50 (ORCPT ); Tue, 25 Nov 2008 11:57:26 -0500 Received: from mail.gmx.net ([213.165.64.20]:43798 "HELO mail.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752023AbYKYQ5Y (ORCPT ); Tue, 25 Nov 2008 11:57:24 -0500 X-Authenticated: #20450766 X-Provags-ID: V01U2FsdGVkX1+ItsElxPmIAqC3MX9UGQaPcvoIuJSR4BO/ARcOku 4rJa+st5YbyYAY Date: Tue, 25 Nov 2008 17:57:31 +0100 (CET) From: Guennadi Liakhovetski X-X-Sender: lyakh@axis700.grange To: rpurdie@rpsys.net cc: linux-kernel@vger.kernel.org Subject: [PATCH] LEDs: allow led-drivers to use a wider than 0...255 range of brightness values Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Y-GMX-Trusted: 0 X-FuHaFi: 0.46 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3919 Lines: 110 This patch allows drivers to override the default maximum brightness value of 255. We take care to preserve backwards-compatibility, so that user-space ABI doesn't change for existing drivers. All existing drivers have been verified to use a zero-initialised memory for their struct led_classdev objects, so that they will get the default maximum value of 255. New user-space software can use a new read-only sysfs file /sys/class/leds/*/max_brightness to retrieve maximum supported brightness of a specific LED. Signed-off-by: Guennadi Liakhovetski --- This will be needed for a new LED driver for an SPI DAC, used as a photo-flash and for camera calibration, so, its brightness has to be adjustable at a finer than 256 levels scale. drivers/leds/led-class.c | 21 ++++++++++++++++++++- drivers/leds/leds.h | 4 ++-- include/linux/leds.h | 1 + 3 files changed, 23 insertions(+), 3 deletions(-) diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c index 6c4a326..c3b4ace 100644 --- a/drivers/leds/led-class.c +++ b/drivers/leds/led-class.c @@ -64,7 +64,16 @@ static ssize_t led_brightness_store(struct device *dev, return ret; } +static ssize_t led_max_brightness_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct led_classdev *led_cdev = dev_get_drvdata(dev); + + return sprintf(buf, "%u\n", led_cdev->max_brightness); +} + static DEVICE_ATTR(brightness, 0644, led_brightness_show, led_brightness_store); +static DEVICE_ATTR(max_brightness, 0444, led_max_brightness_show, NULL); #ifdef CONFIG_LEDS_TRIGGERS static DEVICE_ATTR(trigger, 0644, led_trigger_show, led_trigger_store); #endif @@ -118,6 +127,13 @@ int led_classdev_register(struct device *parent, struct led_classdev *led_cdev) list_add_tail(&led_cdev->node, &leds_list); up_write(&leds_list_lock); + if (!led_cdev->max_brightness) + led_cdev->max_brightness = LED_FULL; + + rc = device_create_file(led_cdev->dev, &dev_attr_max_brightness); + if (rc) + goto err_out_attr_max; + led_update_brightness(led_cdev); #ifdef CONFIG_LEDS_TRIGGERS @@ -135,9 +151,11 @@ int led_classdev_register(struct device *parent, struct led_classdev *led_cdev) #ifdef CONFIG_LEDS_TRIGGERS err_out_led_list: + device_remove_file(led_cdev->dev, &dev_attr_max_brightness); +#endif +err_out_attr_max: device_remove_file(led_cdev->dev, &dev_attr_brightness); list_del(&led_cdev->node); -#endif err_out: device_unregister(led_cdev->dev); return rc; @@ -152,6 +170,7 @@ EXPORT_SYMBOL_GPL(led_classdev_register); */ void led_classdev_unregister(struct led_classdev *led_cdev) { + device_remove_file(led_cdev->dev, &dev_attr_max_brightness); device_remove_file(led_cdev->dev, &dev_attr_brightness); #ifdef CONFIG_LEDS_TRIGGERS device_remove_file(led_cdev->dev, &dev_attr_trigger); diff --git a/drivers/leds/leds.h b/drivers/leds/leds.h index 5edbf52..2dd8ecb 100644 --- a/drivers/leds/leds.h +++ b/drivers/leds/leds.h @@ -20,8 +20,8 @@ static inline void led_set_brightness(struct led_classdev *led_cdev, enum led_brightness value) { - if (value > LED_FULL) - value = LED_FULL; + if (value > led_cdev->max_brightness) + value = led_cdev->max_brightness; led_cdev->brightness = value; if (!(led_cdev->flags & LED_SUSPENDED)) led_cdev->brightness_set(led_cdev, value); diff --git a/include/linux/leds.h b/include/linux/leds.h index d3a73f5..4f8b842 100644 --- a/include/linux/leds.h +++ b/include/linux/leds.h @@ -30,6 +30,7 @@ enum led_brightness { struct led_classdev { const char *name; int brightness; + int max_brightness; int flags; #define LED_SUSPENDED (1 << 0) -- 1.5.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/