1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * PWM-based multi-color LED control
  4 *
  5 * Copyright 2022 Sven Schwermer <sven.schwermer@disruptive-technologies.com>
  6 */
  7
  8#include <linux/err.h>
  9#include <linux/kernel.h>
 10#include <linux/led-class-multicolor.h>
 11#include <linux/leds.h>
 12#include <linux/mod_devicetable.h>
 13#include <linux/module.h>
 14#include <linux/mutex.h>
 15#include <linux/platform_device.h>
 16#include <linux/property.h>
 17#include <linux/pwm.h>
 18
 19struct pwm_led {
 20	struct pwm_device *pwm;
 21	struct pwm_state state;
 22	bool active_low;
 23};
 24
 25struct pwm_mc_led {
 26	struct led_classdev_mc mc_cdev;
 27	struct mutex lock;
 28	struct pwm_led leds[];
 29};
 30
 31static int led_pwm_mc_set(struct led_classdev *cdev,
 32			  enum led_brightness brightness)
 33{
 34	struct led_classdev_mc *mc_cdev = lcdev_to_mccdev(cdev);
 35	struct pwm_mc_led *priv = container_of(mc_cdev, struct pwm_mc_led, mc_cdev);
 36	unsigned long long duty;
 37	int ret = 0;
 38	int i;
 39
 40	led_mc_calc_color_components(mc_cdev, brightness);
 41
 42	mutex_lock(&priv->lock);
 43
 44	for (i = 0; i < mc_cdev->num_colors; i++) {
 45		duty = priv->leds[i].state.period;
 46		duty *= mc_cdev->subled_info[i].brightness;
 47		do_div(duty, cdev->max_brightness);
 48
 49		if (priv->leds[i].active_low)
 50			duty = priv->leds[i].state.period - duty;
 51
 52		priv->leds[i].state.duty_cycle = duty;
 53		priv->leds[i].state.enabled = duty > 0;
 54		ret = pwm_apply_state(priv->leds[i].pwm,
 55				      &priv->leds[i].state);
 56		if (ret)
 57			break;
 58	}
 59
 60	mutex_unlock(&priv->lock);
 61
 62	return ret;
 63}
 64
 65static int iterate_subleds(struct device *dev, struct pwm_mc_led *priv,
 66			   struct fwnode_handle *mcnode)
 67{
 68	struct mc_subled *subled = priv->mc_cdev.subled_info;
 69	struct fwnode_handle *fwnode;
 70	struct pwm_led *pwmled;
 71	u32 color;
 72	int ret;
 73
 74	/* iterate over the nodes inside the multi-led node */
 75	fwnode_for_each_child_node(mcnode, fwnode) {
 76		pwmled = &priv->leds[priv->mc_cdev.num_colors];
 77		pwmled->pwm = devm_fwnode_pwm_get(dev, fwnode, NULL);
 78		if (IS_ERR(pwmled->pwm)) {
 79			ret = dev_err_probe(dev, PTR_ERR(pwmled->pwm), "unable to request PWM\n");
 80			goto release_fwnode;
 81		}
 82		pwm_init_state(pwmled->pwm, &pwmled->state);
 83		pwmled->active_low = fwnode_property_read_bool(fwnode, "active-low");
 84
 85		ret = fwnode_property_read_u32(fwnode, "color", &color);
 86		if (ret) {
 87			dev_err(dev, "cannot read color: %d\n", ret);
 88			goto release_fwnode;
 89		}
 90
 91		subled[priv->mc_cdev.num_colors].color_index = color;
 92		priv->mc_cdev.num_colors++;
 93	}
 94
 95	return 0;
 96
 97release_fwnode:
 98	fwnode_handle_put(fwnode);
 99	return ret;
100}
101
102static int led_pwm_mc_probe(struct platform_device *pdev)
103{
104	struct fwnode_handle *mcnode, *fwnode;
105	struct led_init_data init_data = {};
106	struct led_classdev *cdev;
107	struct mc_subled *subled;
108	struct pwm_mc_led *priv;
109	int count = 0;
110	int ret = 0;
111
112	mcnode = device_get_named_child_node(&pdev->dev, "multi-led");
113	if (!mcnode)
114		return dev_err_probe(&pdev->dev, -ENODEV,
115				     "expected multi-led node\n");
116
117	/* count the nodes inside the multi-led node */
118	fwnode_for_each_child_node(mcnode, fwnode)
119		count++;
120
121	priv = devm_kzalloc(&pdev->dev, struct_size(priv, leds, count),
122			    GFP_KERNEL);
123	if (!priv) {
124		ret = -ENOMEM;
125		goto release_mcnode;
126	}
127	mutex_init(&priv->lock);
128
129	subled = devm_kcalloc(&pdev->dev, count, sizeof(*subled), GFP_KERNEL);
130	if (!subled) {
131		ret = -ENOMEM;
132		goto release_mcnode;
133	}
134	priv->mc_cdev.subled_info = subled;
135
136	/* init the multicolor's LED class device */
137	cdev = &priv->mc_cdev.led_cdev;
138	fwnode_property_read_u32(mcnode, "max-brightness",
139				 &cdev->max_brightness);
140	cdev->flags = LED_CORE_SUSPENDRESUME;
141	cdev->brightness_set_blocking = led_pwm_mc_set;
142
143	ret = iterate_subleds(&pdev->dev, priv, mcnode);
144	if (ret)
145		goto release_mcnode;
146
147	init_data.fwnode = mcnode;
148	ret = devm_led_classdev_multicolor_register_ext(&pdev->dev,
149							&priv->mc_cdev,
150							&init_data);
151	if (ret) {
152		dev_err(&pdev->dev,
153			"failed to register multicolor PWM led for %s: %d\n",
154			cdev->name, ret);
155		goto release_mcnode;
156	}
157
158	ret = led_pwm_mc_set(cdev, cdev->brightness);
159	if (ret)
160		return dev_err_probe(&pdev->dev, ret,
161				     "failed to set led PWM value for %s: %d",
162				     cdev->name, ret);
163
164	platform_set_drvdata(pdev, priv);
165	return 0;
166
167release_mcnode:
168	fwnode_handle_put(mcnode);
169	return ret;
170}
171
172static const struct of_device_id of_pwm_leds_mc_match[] = {
173	{ .compatible = "pwm-leds-multicolor", },
174	{}
175};
176MODULE_DEVICE_TABLE(of, of_pwm_leds_mc_match);
177
178static struct platform_driver led_pwm_mc_driver = {
179	.probe		= led_pwm_mc_probe,
180	.driver		= {
181		.name	= "leds_pwm_multicolor",
182		.of_match_table = of_pwm_leds_mc_match,
183	},
184};
185module_platform_driver(led_pwm_mc_driver);
186
187MODULE_AUTHOR("Sven Schwermer <sven.schwermer@disruptive-technologies.com>");
188MODULE_DESCRIPTION("multi-color PWM LED driver");
189MODULE_LICENSE("GPL v2");
190MODULE_ALIAS("platform:leds-pwm-multicolor");