Commit df7083b5 authored by Guido Günther's avatar Guido Günther Committed by Pavel
Browse files

leds: lm3692x: Make sure we don't exceed the maximum LED current 

The current is given by the formular from page 12 of
https://www.ti.com/lit/ds/symlink/lm36922.pdf

. We use this to limit the
led's max_brightness using the led-max-microamp DT property.

The formula for the lm36923 is identical according to the data sheet.

Signed-off-by: default avatarGuido Günther <agx@sigxcpu.org>
Acked-by: default avatarPavel Machek <pavel@ucw.cz>
Signed-off-by: default avatarPavel Machek <pavel@ucw.cz>
parent 3e0801b6

drivers/leds/leds-lm3692x.c

+19 −1
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ 
#include <linux/i2c.h>

#include <linux/init.h>

#include <linux/leds.h>

#include <linux/log2.h>

#include <linux/module.h>

#include <linux/mutex.h>

#include <linux/of.h>
@@ -321,11 +322,24 @@ static int lm3692x_init(struct lm3692x_led *led) 
	return ret;

}



static enum led_brightness lm3692x_max_brightness(struct lm3692x_led *led,

						  u32 max_cur)

{

	u32 max_code;



	/* see p.12 of LM36922 data sheet for brightness formula */

	max_code = ((max_cur * 1000) - 37806) / 12195;

	if (max_code > 0x7FF)

		max_code = 0x7FF;



	return max_code >> 3;

}



static int lm3692x_probe_dt(struct lm3692x_led *led)

{

	struct fwnode_handle *child = NULL;

	struct led_init_data init_data = {};

	u32 ovp;

	u32 ovp, max_cur;

	int ret;



	led->enable_gpio = devm_gpiod_get_optional(&led->client->dev,
@@ -391,6 +405,10 @@ static int lm3692x_probe_dt(struct lm3692x_led *led) 
		return ret;

	}



	ret = fwnode_property_read_u32(child, "led-max-microamp", &max_cur);

	led->led_dev.max_brightness = ret ? LED_FULL :

		lm3692x_max_brightness(led, max_cur);



	init_data.fwnode = child;

	init_data.devicename = led->client->name;

	init_data.default_label = ":";