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Subject[patch] Move led attributes out of device name and into sysfs attributes, was Re: LED devices
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Date
On Thu, 2007-05-31 at 00:24 -0700, Greg KH wrote: 
> On Wed, May 30, 2007 at 05:19:31PM +0100, Richard Purdie wrote:
> > On Wed, 2007-05-30 at 16:34 +0100, Richard Hughes wrote:
> > > I've talked with other kernel guys here at red hat and they don't think
> > > putting properties in the handle is a good idea.
> > >
> > > I've cc'd Kay, Greg KH and a few other developers for comments.
> > >
> > > To summarize, the LED device class creates a device with a ":" delimited
> > > handle, where properties that are not going to changed get included in
> > > the handle name for userspace to parse with sscanf. For
> > > example, /sys/class/leds/thinklight:blue:keyboard_backlight/brightness
> > >
> > > I think this breaks the one-value-per sysfs file rule and sure makes it
> > > more difficult to extract information in HAL. The backlight class should
> > > have an attribute "color" and "function" so new properties can be added
> > > (or ones that make no sense removed) without breaking API, but the
> > > maintainer doesn't like that idea.
> >
> > I will put my side (as the above maintainer) across. When deciding on
> > the naming for the LEDs in /sys/class/leds/ we had several choices.
> > Taking my handheld as an example, some choices were:
> >
> > /sys/class/leds/led0/
> > /sys/class/leds/led1/
>
> Yes.
>
> > /sys/class/leds/spitz0/
> > /sys/class/leds/spitz1/
>
> Yes.
>
> > /sys/class/leds/spitz:amber/
> > /sys/class/leds/spitz:green/
>
> No way! Don't do that.
>
> > The first contains no useful information, the second one is only
> > fractionally better, the third is actually quite useful. Faced with the
> > third name, a person can actually point to the right LED on the device.
>
> So? You need to read the attributes in the sysfs device directory to
> find out exactly what type of device this is, what it does, and all
> sorts of other information.
>
> The first two examples above are correct. They use a "bus id" type
> naming scheme, like ALL OTHER DEVICES IN THE KERNEL. The only
> requirement is that it is unique.
>
> Userspace programs, like HAL, can handle the fact that spitz0 is really
> a gree LED and it means that the device is charging. That all comes
> from the individual sysfs files.
>
> So please, don't imbend sysfs attributes into the bus id for the device,
> that's just wrong on so many levels...
>
> > As far as the class is concerned, LED colour is a static property (it
> > could handle multi coloured through multiple LED devices).
>
> Yes, and as a property, it needs to be an attribute, not the bus id.
>
> Do you really want to see /sys/bus/usb/devices/usb:hub23 or
> /sys/bus/usb/devices/usb:nerf_rocket_launcher3 ? No, just read the
> attributes to determine the type of the device, like all other devices.
>
> Please, if this is the way that the code is currently working, change it
> now.

Kay,

Patch attached corrects all the brokenness with the led class (encoding
some attributes in the device handle).

Documentation/leds-class.txt | 13 --------
drivers/leds/led-class.c | 62 ++++++++++++++++++++++++++++++++++++++--
drivers/leds/leds-ams-delta.c | 18 +++++++----
drivers/leds/leds-corgi.c | 8 +++--
drivers/leds/leds-h1940.c | 12 +++++--
drivers/leds/leds-locomo.c | 8 +++--
drivers/leds/leds-net48xx.c | 3 +
drivers/leds/leds-spitz.c | 8 +++--
drivers/leds/leds-tosa.c | 8 +++--
drivers/leds/leds-wrap.c | 6 ++-
drivers/macintosh/via-pmu-led.c | 1
drivers/misc/asus-laptop.c | 3 +
include/linux/leds.h | 2 +
13 files changed, 115 insertions(+), 37 deletions(-)
Signed-off-by: Richard Hughes <richard@hughsie.com>

Please review attached patch, thanks.

diff --git a/Documentation/leds-class.txt b/Documentation/leds-class.txt
index 8c35c04..083222b 100644
--- a/Documentation/leds-class.txt
+++ b/Documentation/leds-class.txt
@@ -34,19 +34,6 @@ and the aim is to keep a small amount of code giving as much functionality
as possible. Please keep this in mind when suggesting enhancements.


-LED Device Naming
-=================
-
-Is currently of the form:
-
-"devicename:colour"
-
-There have been calls for LED properties such as colour to be exported as
-individual led class attributes. As a solution which doesn't incur as much
-overhead, I suggest these become part of the device name. The naming scheme
-above leaves scope for further attributes should they be needed.
-
-
Known Issues
============

diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 3c17112..42b7355 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -36,6 +36,30 @@ static ssize_t led_brightness_show(struct class_device *dev, char *buf)
return ret;
}

+static ssize_t led_colour_show(struct class_device *dev, char *buf)
+{
+ struct led_classdev *led_cdev = class_get_devdata(dev);
+ ssize_t ret = 0;
+
+ /* no lock needed for this */
+ sprintf(buf, "%s\n", led_cdev->colour);
+ ret = strlen(buf) + 1;
+
+ return ret;
+}
+
+static ssize_t led_description_show(struct class_device *dev, char *buf)
+{
+ struct led_classdev *led_cdev = class_get_devdata(dev);
+ ssize_t ret = 0;
+
+ /* no lock needed for this */
+ sprintf(buf, "%s\n", led_cdev->description);
+ ret = strlen(buf) + 1;
+
+ return ret;
+}
+
static ssize_t led_brightness_store(struct class_device *dev,
const char *buf, size_t size)
{
@@ -58,6 +82,8 @@ static ssize_t led_brightness_store(struct class_device *dev,

static CLASS_DEVICE_ATTR(brightness, 0644, led_brightness_show,
led_brightness_store);
+static CLASS_DEVICE_ATTR(colour, 0644, led_colour_show, NULL);
+static CLASS_DEVICE_ATTR(description, 0644, led_description_show, NULL);
#ifdef CONFIG_LEDS_TRIGGERS
static CLASS_DEVICE_ATTR(trigger, 0644, led_trigger_show, led_trigger_store);
#endif
@@ -106,6 +132,19 @@ int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
if (rc)
goto err_out;

+ /* these are optional */
+ if (led_cdev->colour)
+ rc = class_device_create_file(led_cdev->class_dev,
+ &class_device_attr_colour);
+ if (rc)
+ goto err_out_brightness;
+ if (led_cdev->description)
+ rc = class_device_create_file(led_cdev->class_dev,
+ &class_device_attr_description);
+ if (rc)
+ goto err_out_colour;
+
+
/* add to the list of leds */
write_lock(&leds_list_lock);
list_add_tail(&led_cdev->node, &leds_list);
@@ -129,12 +168,23 @@ int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)

#ifdef CONFIG_LEDS_TRIGGERS
err_out_led_list:
- class_device_remove_file(led_cdev->class_dev,
- &class_device_attr_brightness);
- list_del(&led_cdev->node);
+ if (led_cdev->description)
+ class_device_remove_file(led_cdev->class_dev,
+ &class_device_attr_description);
#endif
+
+err_out_colour:
+ if (led_cdev->colour)
+ class_device_remove_file(led_cdev->class_dev,
+ &class_device_attr_colour);
+err_out_brightness:
+ class_device_remove_file(led_cdev->class_dev,
+ &class_device_attr_brightness);
err_out:
class_device_unregister(led_cdev->class_dev);
+
+ list_del(&led_cdev->node);
+
return rc;
}
EXPORT_SYMBOL_GPL(led_classdev_register);
@@ -149,6 +199,12 @@ void led_classdev_unregister(struct led_classdev *led_cdev)
{
class_device_remove_file(led_cdev->class_dev,
&class_device_attr_brightness);
+ if (led_cdev->colour)
+ class_device_remove_file(led_cdev->class_dev,
+ &class_device_attr_colour);
+ if (led_cdev->description)
+ class_device_remove_file(led_cdev->class_dev,
+ &class_device_attr_description);
#ifdef CONFIG_LEDS_TRIGGERS
class_device_remove_file(led_cdev->class_dev,
&class_device_attr_trigger);
diff --git a/drivers/leds/leds-ams-delta.c b/drivers/leds/leds-ams-delta.c
index 599878c..21b1bef 100644
--- a/drivers/leds/leds-ams-delta.c
+++ b/drivers/leds/leds-ams-delta.c
@@ -37,42 +37,48 @@ static void ams_delta_led_set(struct led_classdev *led_cdev,
static struct ams_delta_led ams_delta_leds[] = {
{
.cdev = {
- .name = "ams-delta:camera",
+ .name = "ams-delta-camera",
+ .description = "camera",
.brightness_set = ams_delta_led_set,
},
.bitmask = AMS_DELTA_LATCH1_LED_CAMERA,
},
{
.cdev = {
- .name = "ams-delta:advert",
+ .name = "ams-delta-advert",
+ .description = "advert",
.brightness_set = ams_delta_led_set,
},
.bitmask = AMS_DELTA_LATCH1_LED_ADVERT,
},
{
.cdev = {
- .name = "ams-delta:email",
+ .name = "ams-delta-email",
+ .description = "email",
.brightness_set = ams_delta_led_set,
},
.bitmask = AMS_DELTA_LATCH1_LED_EMAIL,
},
{
.cdev = {
- .name = "ams-delta:handsfree",
+ .name = "ams-delta-handsfree",
+ .description = "handsfree",
.brightness_set = ams_delta_led_set,
},
.bitmask = AMS_DELTA_LATCH1_LED_HANDSFREE,
},
{
.cdev = {
- .name = "ams-delta:voicemail",
+ .name = "ams-delta-voicemail",
+ .description = "voicemail",
.brightness_set = ams_delta_led_set,
},
.bitmask = AMS_DELTA_LATCH1_LED_VOICEMAIL,
},
{
.cdev = {
- .name = "ams-delta:voice",
+ .name = "ams-delta-voice",
+ .description = "voice",
.brightness_set = ams_delta_led_set,
},
.bitmask = AMS_DELTA_LATCH1_LED_VOICE,
diff --git a/drivers/leds/leds-corgi.c b/drivers/leds/leds-corgi.c
index cf1dcd7..eeb5a7c 100644
--- a/drivers/leds/leds-corgi.c
+++ b/drivers/leds/leds-corgi.c
@@ -38,13 +38,17 @@ static void corgiled_green_set(struct led_classdev *led_cdev, enum led_brightnes
}

static struct led_classdev corgi_amber_led = {
- .name = "corgi:amber",
+ .name = "corgi_charge",
+ .colour = "amber",
+ .description = "charge",
.default_trigger = "sharpsl-charge",
.brightness_set = corgiled_amber_set,
};

static struct led_classdev corgi_green_led = {
- .name = "corgi:green",
+ .name = "corgi_disk",
+ .colour = "green",
+ .description = "disk",
.default_trigger = "nand-disk",
.brightness_set = corgiled_green_set,
};
diff --git a/drivers/leds/leds-h1940.c b/drivers/leds/leds-h1940.c
index 677c993..d134c79 100644
--- a/drivers/leds/leds-h1940.c
+++ b/drivers/leds/leds-h1940.c
@@ -44,7 +44,9 @@ void h1940_greenled_set(struct led_classdev *led_dev, enum led_brightness value)
}

static struct led_classdev h1940_greenled = {
- .name = "h1940:green",
+ .name = "h1940_green",
+ .colour = "green",
+ .description = "charger",
.brightness_set = h1940_greenled_set,
.default_trigger = "h1940-charger",
};
@@ -73,7 +75,9 @@ void h1940_redled_set(struct led_classdev *led_dev, enum led_brightness value)
}

static struct led_classdev h1940_redled = {
- .name = "h1940:red",
+ .name = "h1940_charger",
+ .colour = "red",
+ .description = "charger",
.brightness_set = h1940_redled_set,
.default_trigger = "h1940-charger",
};
@@ -96,7 +100,9 @@ void h1940_blueled_set(struct led_classdev *led_dev, enum led_brightness value)
}

static struct led_classdev h1940_blueled = {
- .name = "h1940:blue",
+ .name = "h1940_bluetooth",
+ .colour = "blue",
+ .description = "bluetooth",
.brightness_set = h1940_blueled_set,
.default_trigger = "h1940-bluetooth",
};
diff --git a/drivers/leds/leds-locomo.c b/drivers/leds/leds-locomo.c
index 6f2d449..0e297d4 100644
--- a/drivers/leds/leds-locomo.c
+++ b/drivers/leds/leds-locomo.c
@@ -43,13 +43,17 @@ static void locomoled_brightness_set1(struct led_classdev *led_cdev,
}

static struct led_classdev locomo_led0 = {
- .name = "locomo:amber",
+ .name = "locomo_charge",
+ .colour = "amber",
+ .description = "charge",
.default_trigger = "sharpsl-charge",
.brightness_set = locomoled_brightness_set0,
};

static struct led_classdev locomo_led1 = {
- .name = "locomo:green",
+ .name = "locomo_disk",
+ .colour = "green",
+ .description = "disk",
.default_trigger = "nand-disk",
.brightness_set = locomoled_brightness_set1,
};
diff --git a/drivers/leds/leds-net48xx.c b/drivers/leds/leds-net48xx.c
index 45ba3d4..5e21553 100644
--- a/drivers/leds/leds-net48xx.c
+++ b/drivers/leds/leds-net48xx.c
@@ -31,7 +31,8 @@ static void net48xx_error_led_set(struct led_classdev *led_cdev,
}

static struct led_classdev net48xx_error_led = {
- .name = "net48xx:error",
+ .name = "net48xx_error",
+ .description = "error",
.brightness_set = net48xx_error_led_set,
};

diff --git a/drivers/leds/leds-spitz.c b/drivers/leds/leds-spitz.c
index 126d09c..b8340ab 100644
--- a/drivers/leds/leds-spitz.c
+++ b/drivers/leds/leds-spitz.c
@@ -38,13 +38,17 @@ static void spitzled_green_set(struct led_classdev *led_cdev, enum led_brightnes
}

static struct led_classdev spitz_amber_led = {
- .name = "spitz:amber",
+ .name = "spitz_charge",
+ .colour = "amber",
+ .description = "charge",
.default_trigger = "sharpsl-charge",
.brightness_set = spitzled_amber_set,
};

static struct led_classdev spitz_green_led = {
- .name = "spitz:green",
+ .name = "spitz_disk",
+ .colour = "green",
+ .description = "disk",
.default_trigger = "ide-disk",
.brightness_set = spitzled_green_set,
};
diff --git a/drivers/leds/leds-tosa.c b/drivers/leds/leds-tosa.c
index fb2416a..6e2fb39 100644
--- a/drivers/leds/leds-tosa.c
+++ b/drivers/leds/leds-tosa.c
@@ -45,13 +45,17 @@ static void tosaled_green_set(struct led_classdev *led_cdev,
}

static struct led_classdev tosa_amber_led = {
- .name = "tosa:amber",
+ .name = "tosa_charge",
+ .colour = "amber",
+ .description = "charge",
.default_trigger = "sharpsl-charge",
.brightness_set = tosaled_amber_set,
};

static struct led_classdev tosa_green_led = {
- .name = "tosa:green",
+ .name = "tosa_disk",
+ .colour = "green",
+ .description = "disk",
.default_trigger = "nand-disk",
.brightness_set = tosaled_green_set,
};
diff --git a/drivers/leds/leds-wrap.c b/drivers/leds/leds-wrap.c
index 27fb2d8..1daa13e 100644
--- a/drivers/leds/leds-wrap.c
+++ b/drivers/leds/leds-wrap.c
@@ -43,12 +43,14 @@ static void wrap_extra_led_set(struct led_classdev *led_cdev,
}

static struct led_classdev wrap_error_led = {
- .name = "wrap:error",
+ .name = "wrap_error",
+ .description = "error",
.brightness_set = wrap_error_led_set,
};

static struct led_classdev wrap_extra_led = {
- .name = "wrap:extra",
+ .name = "wrap_extra",
+ .description = "extra",
.brightness_set = wrap_extra_led_set,
};

diff --git a/drivers/macintosh/via-pmu-led.c b/drivers/macintosh/via-pmu-led.c
index 55ad956..b67a95a 100644
--- a/drivers/macintosh/via-pmu-led.c
+++ b/drivers/macintosh/via-pmu-led.c
@@ -73,6 +73,7 @@ static void pmu_led_set(struct led_classdev *led_cdev,

static struct led_classdev pmu_led = {
.name = "pmu-front-led",
+ .description = "front-led",
#ifdef CONFIG_ADB_PMU_LED_IDE
.default_trigger = "ide-disk",
#endif
diff --git a/drivers/misc/asus-laptop.c b/drivers/misc/asus-laptop.c
index 4f9060a..d7f1175 100644
--- a/drivers/misc/asus-laptop.c
+++ b/drivers/misc/asus-laptop.c
@@ -235,7 +235,8 @@ static struct workqueue_struct *led_workqueue;
static int object##_led_wk; \
static DECLARE_WORK(object##_led_work, object##_led_update); \
static struct led_classdev object##_led = { \
- .name = "asus:" ledname, \
+ .name = "asus_" ledname, \
+ .description = ledname, \
.brightness_set = object##_led_set, \
}

diff --git a/include/linux/leds.h b/include/linux/leds.h
index 88afcef..c9cb394 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -41,6 +41,8 @@ struct led_classdev {
struct class_device *class_dev;
struct list_head node; /* LED Device list */
char *default_trigger; /* Trigger to use */
+ char *colour; /* Colour of the LED */
+ char *description; /* Description of purpose */

#ifdef CONFIG_LEDS_TRIGGERS
/* Protects the trigger data below */
\
 
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