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


    > + 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,
    >


    --
    ------------------
    Dan Murphy

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