1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * PWM-based multi-color LED control
4 *
5 * Copyright 2022 Sven Schwermer <[email protected]>
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 /*
54 * Disabling a PWM doesn't guarantee that it emits the inactive level.
55 * So keep it on. Only for suspending the PWM should be disabled because
56 * otherwise it refuses to suspend. The possible downside is that the
57 * LED might stay (or even go) on.
58 */
59 priv->leds[i].state.enabled = !(cdev->flags & LED_SUSPENDED);
60 ret = pwm_apply_might_sleep(priv->leds[i].pwm,
61 &priv->leds[i].state);
62 if (ret)
63 break;
64 }
65
66 mutex_unlock(&priv->lock);
67
68 return ret;
69 }
70
iterate_subleds(struct device * dev,struct pwm_mc_led * priv,struct fwnode_handle * mcnode)71 static int iterate_subleds(struct device *dev, struct pwm_mc_led *priv,
72 struct fwnode_handle *mcnode)
73 {
74 struct mc_subled *subled = priv->mc_cdev.subled_info;
75 struct fwnode_handle *fwnode;
76 struct pwm_led *pwmled;
77 u32 color;
78 int ret;
79
80 /* iterate over the nodes inside the multi-led node */
81 fwnode_for_each_child_node(mcnode, fwnode) {
82 pwmled = &priv->leds[priv->mc_cdev.num_colors];
83 pwmled->pwm = devm_fwnode_pwm_get(dev, fwnode, NULL);
84 if (IS_ERR(pwmled->pwm)) {
85 ret = dev_err_probe(dev, PTR_ERR(pwmled->pwm), "unable to request PWM\n");
86 goto release_fwnode;
87 }
88 pwm_init_state(pwmled->pwm, &pwmled->state);
89 pwmled->active_low = fwnode_property_read_bool(fwnode, "active-low");
90
91 ret = fwnode_property_read_u32(fwnode, "color", &color);
92 if (ret) {
93 dev_err(dev, "cannot read color: %d\n", ret);
94 goto release_fwnode;
95 }
96
97 subled[priv->mc_cdev.num_colors].color_index = color;
98 priv->mc_cdev.num_colors++;
99 }
100
101 return 0;
102
103 release_fwnode:
104 fwnode_handle_put(fwnode);
105 return ret;
106 }
107
led_pwm_mc_probe(struct platform_device * pdev)108 static int led_pwm_mc_probe(struct platform_device *pdev)
109 {
110 struct fwnode_handle *mcnode, *fwnode;
111 struct led_init_data init_data = {};
112 struct led_classdev *cdev;
113 struct mc_subled *subled;
114 struct pwm_mc_led *priv;
115 int count = 0;
116 int ret = 0;
117
118 mcnode = device_get_named_child_node(&pdev->dev, "multi-led");
119 if (!mcnode)
120 return dev_err_probe(&pdev->dev, -ENODEV,
121 "expected multi-led node\n");
122
123 /* count the nodes inside the multi-led node */
124 fwnode_for_each_child_node(mcnode, fwnode)
125 count++;
126
127 priv = devm_kzalloc(&pdev->dev, struct_size(priv, leds, count),
128 GFP_KERNEL);
129 if (!priv) {
130 ret = -ENOMEM;
131 goto release_mcnode;
132 }
133 mutex_init(&priv->lock);
134
135 subled = devm_kcalloc(&pdev->dev, count, sizeof(*subled), GFP_KERNEL);
136 if (!subled) {
137 ret = -ENOMEM;
138 goto release_mcnode;
139 }
140 priv->mc_cdev.subled_info = subled;
141
142 /* init the multicolor's LED class device */
143 cdev = &priv->mc_cdev.led_cdev;
144 fwnode_property_read_u32(mcnode, "max-brightness",
145 &cdev->max_brightness);
146 cdev->flags = LED_CORE_SUSPENDRESUME;
147 cdev->brightness_set_blocking = led_pwm_mc_set;
148
149 ret = iterate_subleds(&pdev->dev, priv, mcnode);
150 if (ret)
151 goto release_mcnode;
152
153 init_data.fwnode = mcnode;
154 ret = devm_led_classdev_multicolor_register_ext(&pdev->dev,
155 &priv->mc_cdev,
156 &init_data);
157 if (ret) {
158 dev_err(&pdev->dev,
159 "failed to register multicolor PWM led for %s: %d\n",
160 cdev->name, ret);
161 goto release_mcnode;
162 }
163
164 ret = led_pwm_mc_set(cdev, cdev->brightness);
165 if (ret)
166 return dev_err_probe(&pdev->dev, ret,
167 "failed to set led PWM value for %s\n",
168 cdev->name);
169
170 platform_set_drvdata(pdev, priv);
171 return 0;
172
173 release_mcnode:
174 fwnode_handle_put(mcnode);
175 return ret;
176 }
177
178 static const struct of_device_id of_pwm_leds_mc_match[] = {
179 { .compatible = "pwm-leds-multicolor", },
180 {}
181 };
182 MODULE_DEVICE_TABLE(of, of_pwm_leds_mc_match);
183
184 static struct platform_driver led_pwm_mc_driver = {
185 .probe = led_pwm_mc_probe,
186 .driver = {
187 .name = "leds_pwm_multicolor",
188 .of_match_table = of_pwm_leds_mc_match,
189 },
190 };
191 module_platform_driver(led_pwm_mc_driver);
192
193 MODULE_AUTHOR("Sven Schwermer <[email protected]>");
194 MODULE_DESCRIPTION("multi-color PWM LED driver");
195 MODULE_LICENSE("GPL v2");
196 MODULE_ALIAS("platform:leds-pwm-multicolor");
197