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 
19 struct pwm_led {
20 	struct pwm_device *pwm;
21 	struct pwm_state state;
22 	bool active_low;
23 };
24 
25 struct pwm_mc_led {
26 	struct led_classdev_mc mc_cdev;
27 	struct mutex lock;
28 	struct pwm_led leds[];
29 };
30 
led_pwm_mc_set(struct led_classdev * cdev,enum led_brightness brightness)31 static 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_might_sleep(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 
iterate_subleds(struct device * dev,struct pwm_mc_led * priv,struct fwnode_handle * mcnode)65 static 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 
97 release_fwnode:
98 	fwnode_handle_put(fwnode);
99 	return ret;
100 }
101 
led_pwm_mc_probe(struct platform_device * pdev)102 static 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\n",
162 				     cdev->name);
163 
164 	platform_set_drvdata(pdev, priv);
165 	return 0;
166 
167 release_mcnode:
168 	fwnode_handle_put(mcnode);
169 	return ret;
170 }
171 
172 static const struct of_device_id of_pwm_leds_mc_match[] = {
173 	{ .compatible = "pwm-leds-multicolor", },
174 	{}
175 };
176 MODULE_DEVICE_TABLE(of, of_pwm_leds_mc_match);
177 
178 static 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 };
185 module_platform_driver(led_pwm_mc_driver);
186 
187 MODULE_AUTHOR("Sven Schwermer <sven.schwermer@disruptive-technologies.com>");
188 MODULE_DESCRIPTION("multi-color PWM LED driver");
189 MODULE_LICENSE("GPL v2");
190 MODULE_ALIAS("platform:leds-pwm-multicolor");
191