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