leds/rgb/leds-pwm-multicolor.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * PWM-based multi-color LED control
0004  *
0005  * Copyright 2022 Sven Schwermer <sven.schwermer@disruptive-technologies.com>
0006  */
0007
0008 #include <linux/err.h>
0009 #include <linux/kernel.h>
0010 #include <linux/led-class-multicolor.h>
0011 #include <linux/leds.h>
0012 #include <linux/mod_devicetable.h>
0013 #include <linux/module.h>
0014 #include <linux/mutex.h>
0015 #include <linux/platform_device.h>
0016 #include <linux/property.h>
0017 #include <linux/pwm.h>
0018
0019 struct pwm_led {
0020     struct pwm_device *pwm;
0021     struct pwm_state state;
0022     bool active_low;
0023 };
0024
0025 struct pwm_mc_led {
0026     struct led_classdev_mc mc_cdev;
0027     struct mutex lock;
0028     struct pwm_led leds[];
0029 };
0030
0031 static int led_pwm_mc_set(struct led_classdev *cdev,
0032               enum led_brightness brightness)
0033 {
0034     struct led_classdev_mc *mc_cdev = lcdev_to_mccdev(cdev);
0035     struct pwm_mc_led *priv = container_of(mc_cdev, struct pwm_mc_led, mc_cdev);
0036     unsigned long long duty;
0037     int ret = 0;
0038     int i;
0039
0040     led_mc_calc_color_components(mc_cdev, brightness);
0041
0042     mutex_lock(&priv->lock);
0043
0044     for (i = 0; i < mc_cdev->num_colors; i++) {
0045         duty = priv->leds[i].state.period;
0046         duty *= mc_cdev->subled_info[i].brightness;
0047         do_div(duty, cdev->max_brightness);
0048
0049         if (priv->leds[i].active_low)
0050             duty = priv->leds[i].state.period - duty;
0051
0052         priv->leds[i].state.duty_cycle = duty;
0053         priv->leds[i].state.enabled = duty > 0;
0054         ret = pwm_apply_state(priv->leds[i].pwm,
0055                       &priv->leds[i].state);
0056         if (ret)
0057             break;
0058     }
0059
0060     mutex_unlock(&priv->lock);
0061
0062     return ret;
0063 }
0064
0065 static int iterate_subleds(struct device *dev, struct pwm_mc_led *priv,
0066                struct fwnode_handle *mcnode)
0067 {
0068     struct mc_subled *subled = priv->mc_cdev.subled_info;
0069     struct fwnode_handle *fwnode;
0070     struct pwm_led *pwmled;
0071     u32 color;
0072     int ret;
0073
0074     /* iterate over the nodes inside the multi-led node */
0075     fwnode_for_each_child_node(mcnode, fwnode) {
0076         pwmled = &priv->leds[priv->mc_cdev.num_colors];
0077         pwmled->pwm = devm_fwnode_pwm_get(dev, fwnode, NULL);
0078         if (IS_ERR(pwmled->pwm)) {
0079             ret = dev_err_probe(dev, PTR_ERR(pwmled->pwm), "unable to request PWM\n");
0080             goto release_fwnode;
0081         }
0082         pwm_init_state(pwmled->pwm, &pwmled->state);
0083         pwmled->active_low = fwnode_property_read_bool(fwnode, "active-low");
0084
0085         ret = fwnode_property_read_u32(fwnode, "color", &color);
0086         if (ret) {
0087             dev_err(dev, "cannot read color: %d\n", ret);
0088             goto release_fwnode;
0089         }
0090
0091         subled[priv->mc_cdev.num_colors].color_index = color;
0092         priv->mc_cdev.num_colors++;
0093     }
0094
0095     return 0;
0096
0097 release_fwnode:
0098     fwnode_handle_put(fwnode);
0099     return ret;
0100 }
0101
0102 static int led_pwm_mc_probe(struct platform_device *pdev)
0103 {
0104     struct fwnode_handle *mcnode, *fwnode;
0105     struct led_init_data init_data = {};
0106     struct led_classdev *cdev;
0107     struct mc_subled *subled;
0108     struct pwm_mc_led *priv;
0109     int count = 0;
0110     int ret = 0;
0111
0112     mcnode = device_get_named_child_node(&pdev->dev, "multi-led");
0113     if (!mcnode)
0114         return dev_err_probe(&pdev->dev, -ENODEV,
0115                      "expected multi-led node\n");
0116
0117     /* count the nodes inside the multi-led node */
0118     fwnode_for_each_child_node(mcnode, fwnode)
0119         count++;
0120
0121     priv = devm_kzalloc(&pdev->dev, struct_size(priv, leds, count),
0122                 GFP_KERNEL);
0123     if (!priv) {
0124         ret = -ENOMEM;
0125         goto release_mcnode;
0126     }
0127     mutex_init(&priv->lock);
0128
0129     subled = devm_kcalloc(&pdev->dev, count, sizeof(*subled), GFP_KERNEL);
0130     if (!subled) {
0131         ret = -ENOMEM;
0132         goto release_mcnode;
0133     }
0134     priv->mc_cdev.subled_info = subled;
0135
0136     /* init the multicolor's LED class device */
0137     cdev = &priv->mc_cdev.led_cdev;
0138     fwnode_property_read_u32(mcnode, "max-brightness",
0139                  &cdev->max_brightness);
0140     cdev->flags = LED_CORE_SUSPENDRESUME;
0141     cdev->brightness_set_blocking = led_pwm_mc_set;
0142
0143     ret = iterate_subleds(&pdev->dev, priv, mcnode);
0144     if (ret)
0145         goto release_mcnode;
0146
0147     init_data.fwnode = mcnode;
0148     ret = devm_led_classdev_multicolor_register_ext(&pdev->dev,
0149                             &priv->mc_cdev,
0150                             &init_data);
0151     if (ret) {
0152         dev_err(&pdev->dev,
0153             "failed to register multicolor PWM led for %s: %d\n",
0154             cdev->name, ret);
0155         goto release_mcnode;
0156     }
0157
0158     ret = led_pwm_mc_set(cdev, cdev->brightness);
0159     if (ret)
0160         return dev_err_probe(&pdev->dev, ret,
0161                      "failed to set led PWM value for %s: %d",
0162                      cdev->name, ret);
0163
0164     platform_set_drvdata(pdev, priv);
0165     return 0;
0166
0167 release_mcnode:
0168     fwnode_handle_put(mcnode);
0169     return ret;
0170 }
0171
0172 static const struct of_device_id of_pwm_leds_mc_match[] = {
0173     { .compatible = "pwm-leds-multicolor", },
0174     {}
0175 };
0176 MODULE_DEVICE_TABLE(of, of_pwm_leds_mc_match);
0177
0178 static struct platform_driver led_pwm_mc_driver = {
0179     .probe      = led_pwm_mc_probe,
0180     .driver     = {
0181         .name   = "leds_pwm_multicolor",
0182         .of_match_table = of_pwm_leds_mc_match,
0183     },
0184 };
0185 module_platform_driver(led_pwm_mc_driver);
0186
0187 MODULE_AUTHOR("Sven Schwermer <sven.schwermer@disruptive-technologies.com>");
0188 MODULE_DESCRIPTION("multi-color PWM LED driver");
0189 MODULE_LICENSE("GPL v2");
0190 MODULE_ALIAS("platform:leds-pwm-multicolor");