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SubjectRe: [PATCH 02/24] leds: core: Add support for composing LED class device names
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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@gmail.com>
>> Cc: Baolin Wang <baolin.wang@linaro.org>
>> Cc: Daniel Mack <daniel@zonque.org>
>> Cc: Dan Murphy <dmurphy@ti.com>
>> Cc: Linus Walleij <linus.walleij@linaro.org>
>> Cc: Oleh Kravchenko <oleg@kaa.org.ua>
>> Cc: Sakari Ailus <sakari.ailus@linux.intel.com>
>> Cc: Simon Shields <simon@lineageos.org>
>> Cc: Xiaotong Lu <xiaotong.lu@spreadtrum.com>
>> ---
>> 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

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