Re: [PATCH 02/24] leds: core: Add support for composing LED class device names

[Jacek Anaszewski]

Dan,

On 11/08/2018 07:06 PM, Dan Murphy wrote:
> On 11/06/2018 04:07 PM, Jacek Anaszewski wrote:
>> Add public led_compose_name() API for composing LED class device
>> name basing on fwnode_handle data. The function composes device name
>> according to either a new <color:function> pattern or the legacy
>> <devicename:color:function> pattern. The decision on using the
>> particular pattern is made basing on whether fwnode contains new
>> "function" and "color" properties, or the legacy "label" proeprty.
>>
>> Backwards compatibility with in-driver hard-coded LED class device
>> names is assured thanks to the default_desc argument.
>>
>> In case none of the aformentioned properties was found, then, for OF
>> nodes, the node name is adopted for LED class device name.
>>
>> Signed-off-by: Jacek Anaszewski <jacek.anaszewski@xxxxxxxxx>
>> Cc: Baolin Wang <baolin.wang@xxxxxxxxxx>
>> Cc: Daniel Mack <daniel@xxxxxxxxxx>
>> Cc: Dan Murphy <dmurphy@xxxxxx>
>> Cc: Linus Walleij <linus.walleij@xxxxxxxxxx>
>> Cc: Oleh Kravchenko <oleg@xxxxxxxxxx>
>> Cc: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
>> Cc: Simon Shields <simon@xxxxxxxxxxxxx>
>> Cc: Xiaotong Lu <xiaotong.lu@xxxxxxxxxxxxxx>
>> ---
>>  Documentation/leds/leds-class.txt |  2 +-
>>  drivers/leds/led-core.c           | 71 +++++++++++++++++++++++++++++++++++++++
>>  include/linux/leds.h              | 32 ++++++++++++++++++
>>  3 files changed, 104 insertions(+), 1 deletion(-)
>>
>> diff --git a/Documentation/leds/leds-class.txt b/Documentation/leds/leds-class.txt
>> index 836cb16..e9009c4 100644
>> --- a/Documentation/leds/leds-class.txt
>> +++ b/Documentation/leds/leds-class.txt
>> @@ -43,7 +43,7 @@ LED Device Naming
>>  
>>  Is currently of the form:
>>  
>> -"devicename:colour:function"
>> +"colour:function"
>>  
>>  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
>> diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
>> index ede4fa0..f7371fc 100644
>> --- a/drivers/leds/led-core.c
>> +++ b/drivers/leds/led-core.c
>> @@ -16,6 +16,8 @@
>>  #include <linux/list.h>
>>  #include <linux/module.h>
>>  #include <linux/mutex.h>
>> +#include <linux/of.h>
>> +#include <linux/property.h>
>>  #include <linux/rwsem.h>
>>  #include "leds.h"
>>  
>> @@ -327,3 +329,72 @@ void led_sysfs_enable(struct led_classdev *led_cdev)
>>  	led_cdev->flags &= ~LED_SYSFS_DISABLE;
>>  }
>>  EXPORT_SYMBOL_GPL(led_sysfs_enable);
>> +
>> +static void led_parse_properties(struct fwnode_handle *fwnode,
>> +				 struct led_properties *props)
>> +{
>> +	int ret;
>> +
>> +	if (!fwnode)
>> +		return;
>> +
>> +	ret = fwnode_property_read_string(fwnode, "label", &props->label);
> 
> If we have the label do we need to continue to look for the function and color nodes?
> 
> It can be checked and diverted using fwnode_property_present for the "label" property

Good catch. I will respin it as proposed.

>> +	if (!ret)
>> +		return;
>> +
>> +	ret = fwnode_property_read_string(fwnode, "function", &props->function);
>> +	if (ret)
>> +		pr_info("Failed to parse function property\n");
>> +
>> +	ret = fwnode_property_read_string(fwnode, "color", &props->color);
>> +	if (ret)
>> +		pr_info("Failed to parse color property\n");
>> +}
>> +
>> +int led_compose_name(struct fwnode_handle *fwnode, const char *led_hw_name,
>> +		     const char *default_desc, char *led_classdev_name)
>> +{
>> +	struct led_properties props = {};
>> +
>> +	if (!led_classdev_name)
>> +		return -EINVAL;
>> +
>> +	led_parse_properties(fwnode, &props);
>> +
>> +	if (props.label) {
>> +		/*
>> +		 * Presence of 'label' DT property implies legacy LED name,
>> +		 * formatted as <devicename:color:function>, with possible
>> +		 * section omission if doesn't apply to given device.
>> +		 *
>> +		 * If no led_hw_name has been passed, then it indicates that
>> +		 * DT label should be used as-is for LED class device name.
>> +		 * Otherwise the label is prepended with led_hw_name to compose
>> +		 * the final LED class device name.
>> +		 */
>> +		if (!led_hw_name) {
>> +			strncpy(led_classdev_name, props.label,
>> +				LED_MAX_NAME_SIZE);
>> +		} else {
>> +			snprintf(led_classdev_name, LED_MAX_NAME_SIZE, "%s:%s",
>> +				 led_hw_name, props.label);
>> +		}
>> +	} else if (props.function || props.color) {
>> +		snprintf(led_classdev_name, LED_MAX_NAME_SIZE, "%s:%s",
>> +			 props.color ?: "", props.function ?: "");
>> +	} else if (default_desc) {
>> +		if (!led_hw_name) {
>> +			pr_err("Legacy LED naming requires devicename segment");
>> +			return -EINVAL;
>> +		}
>> +		snprintf(led_classdev_name, LED_MAX_NAME_SIZE, "%s:%s",
>> +			 led_hw_name, default_desc);
>> +	} else if (is_of_node(fwnode)) {
>> +		strncpy(led_classdev_name, to_of_node(fwnode)->name,
>> +			LED_MAX_NAME_SIZE);
>> +	} else
>> +		return -EINVAL;
>> +
>> +	return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(led_compose_name);
>> diff --git a/include/linux/leds.h b/include/linux/leds.h
>> index 646c49a..ddb4001 100644
>> --- a/include/linux/leds.h
>> +++ b/include/linux/leds.h
>> @@ -238,6 +238,32 @@ extern void led_sysfs_disable(struct led_classdev *led_cdev);
>>  extern void led_sysfs_enable(struct led_classdev *led_cdev);
>>  
>>  /**
>> + * led_compose_name - compose LED class device name
>> + * @child: child fwnode_handle describing a LED,
>> + *	   or a group of synchronized LEDs.
>> + * @led_hw_name: name of the LED controller, used when falling back to legacy
>> + *		 LED naming; it should be set to NULL in new LED class drivers
>> + * @default_desc: default <color:function> tuple, for backwards compatibility
>> + *		  with in-driver hard-coded LED names used as a fallback when
>> + *		  "label" DT property was absent; it should be set to NULL
>> + *		  in new LED class drivers
>> + * @led_classdev_name: composed LED class device name
>> + *
>> + * Create LED class device name basing on the configuration provided by the
>> + * board firmware. The name can have a legacy form <devicename:color:function>,
>> + * or a new form <color:function>. The latter is chosen if at least one of
>> + * "color" or "function" properties is present in the fwnode, leaving the
>> + * section blank if the related property is absent. The former is applied
>> + * when legacy "label" property is present in the fwnode. In case none of the
>> + * aformentioned properties was found, then, for OF nodes, the node name
> 
> s/aforementioned
> 
>> + * is adopted for LED class device name.
>> + *
>> + * Returns: 0 on success or negative error value on failure
>> + */
>> +extern int led_compose_name(struct fwnode_handle *child, const char *led_hw_name,
>> +			    const char *default_desc, char *led_classdev_name);
>> +
>> +/**
>>   * led_sysfs_is_disabled - check if LED sysfs interface is disabled
>>   * @led_cdev: the LED to query
>>   *
>> @@ -414,6 +440,12 @@ struct led_platform_data {
>>  	struct led_info	*leds;
>>  };
>>  
>> +struct led_properties {
>> +	const char *color;
>> +	const char *function;
>> +	const char *label;
>> +};
>> +
>>  struct gpio_desc;
>>  typedef int (*gpio_blink_set_t)(struct gpio_desc *desc, int state,
>>  				unsigned long *delay_on,
>>
> 
> 

-- 
Best regards,
Jacek Anaszewski