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 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_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 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 } 101 102 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