1 // SPDX-License-Identifier: GPL-2.0 2 // Copyright (c) 2009,2018 Daniel Mack <daniel@zonque.org> 3 4 #include <linux/kernel.h> 5 #include <linux/platform_device.h> 6 #include <linux/leds.h> 7 #include <linux/delay.h> 8 #include <linux/gpio.h> 9 #include <linux/gpio/consumer.h> 10 #include <linux/slab.h> 11 #include <linux/module.h> 12 #include <linux/of.h> 13 #include <uapi/linux/uleds.h> 14 15 struct lt3593_led_data { 16 char name[LED_MAX_NAME_SIZE]; 17 struct led_classdev cdev; 18 struct gpio_desc *gpiod; 19 }; 20 21 static int lt3593_led_set(struct led_classdev *led_cdev, 22 enum led_brightness value) 23 { 24 struct lt3593_led_data *led_dat = 25 container_of(led_cdev, struct lt3593_led_data, cdev); 26 int pulses; 27 28 /* 29 * The LT3593 resets its internal current level register to the maximum 30 * level on the first falling edge on the control pin. Each following 31 * falling edge decreases the current level by 625uA. Up to 32 pulses 32 * can be sent, so the maximum power reduction is 20mA. 33 * After a timeout of 128us, the value is taken from the register and 34 * applied is to the output driver. 35 */ 36 37 if (value == 0) { 38 gpiod_set_value_cansleep(led_dat->gpiod, 0); 39 return 0; 40 } 41 42 pulses = 32 - (value * 32) / 255; 43 44 if (pulses == 0) { 45 gpiod_set_value_cansleep(led_dat->gpiod, 0); 46 mdelay(1); 47 gpiod_set_value_cansleep(led_dat->gpiod, 1); 48 return 0; 49 } 50 51 gpiod_set_value_cansleep(led_dat->gpiod, 1); 52 53 while (pulses--) { 54 gpiod_set_value_cansleep(led_dat->gpiod, 0); 55 udelay(1); 56 gpiod_set_value_cansleep(led_dat->gpiod, 1); 57 udelay(1); 58 } 59 60 return 0; 61 } 62 63 static struct lt3593_led_data *lt3593_led_probe_pdata(struct device *dev) 64 { 65 struct gpio_led_platform_data *pdata = dev_get_platdata(dev); 66 const struct gpio_led *template = &pdata->leds[0]; 67 struct lt3593_led_data *led_data; 68 int ret, state; 69 70 if (pdata->num_leds != 1) 71 return ERR_PTR(-EINVAL); 72 73 led_data = devm_kzalloc(dev, sizeof(*led_data), GFP_KERNEL); 74 if (!led_data) 75 return ERR_PTR(-ENOMEM); 76 77 led_data->cdev.name = template->name; 78 led_data->cdev.default_trigger = template->default_trigger; 79 led_data->cdev.brightness_set_blocking = lt3593_led_set; 80 81 state = (template->default_state == LEDS_GPIO_DEFSTATE_ON); 82 led_data->cdev.brightness = state ? LED_FULL : LED_OFF; 83 84 if (!template->retain_state_suspended) 85 led_data->cdev.flags |= LED_CORE_SUSPENDRESUME; 86 87 ret = devm_gpio_request_one(dev, template->gpio, state ? 88 GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW, 89 template->name); 90 if (ret < 0) 91 return ERR_PTR(ret); 92 93 led_data->gpiod = gpio_to_desc(template->gpio); 94 if (!led_data->gpiod) 95 return ERR_PTR(-EPROBE_DEFER); 96 97 ret = devm_led_classdev_register(dev, &led_data->cdev); 98 if (ret < 0) 99 return ERR_PTR(ret); 100 101 dev_info(dev, "registered LT3593 LED '%s' at GPIO %d\n", 102 template->name, template->gpio); 103 104 return led_data; 105 } 106 107 static int lt3593_led_probe(struct platform_device *pdev) 108 { 109 struct device *dev = &pdev->dev; 110 struct lt3593_led_data *led_data; 111 struct fwnode_handle *child; 112 int ret, state = LEDS_GPIO_DEFSTATE_OFF; 113 enum gpiod_flags flags = GPIOD_OUT_LOW; 114 const char *tmp; 115 116 if (dev_get_platdata(dev)) { 117 led_data = lt3593_led_probe_pdata(dev); 118 if (IS_ERR(led_data)) 119 return PTR_ERR(led_data); 120 121 goto out; 122 } 123 124 if (!dev->of_node) 125 return -ENODEV; 126 127 led_data = devm_kzalloc(dev, sizeof(*led_data), GFP_KERNEL); 128 if (!led_data) 129 return -ENOMEM; 130 131 if (device_get_child_node_count(dev) != 1) { 132 dev_err(dev, "Device must have exactly one LED sub-node."); 133 return -EINVAL; 134 } 135 136 led_data->gpiod = devm_gpiod_get(dev, "lltc,ctrl", 0); 137 if (IS_ERR(led_data->gpiod)) 138 return PTR_ERR(led_data->gpiod); 139 140 child = device_get_next_child_node(dev, NULL); 141 142 ret = fwnode_property_read_string(child, "label", &tmp); 143 if (ret < 0) 144 snprintf(led_data->name, sizeof(led_data->name), 145 "lt3593::"); 146 else 147 snprintf(led_data->name, sizeof(led_data->name), 148 "lt3593:%s", tmp); 149 150 fwnode_property_read_string(child, "linux,default-trigger", 151 &led_data->cdev.default_trigger); 152 153 if (!fwnode_property_read_string(child, "default-state", &tmp)) { 154 if (!strcmp(tmp, "keep")) { 155 state = LEDS_GPIO_DEFSTATE_KEEP; 156 flags = GPIOD_ASIS; 157 } else if (!strcmp(tmp, "on")) { 158 state = LEDS_GPIO_DEFSTATE_ON; 159 flags = GPIOD_OUT_HIGH; 160 } 161 } 162 163 led_data->cdev.name = led_data->name; 164 led_data->cdev.brightness_set_blocking = lt3593_led_set; 165 led_data->cdev.brightness = state ? LED_FULL : LED_OFF; 166 167 ret = devm_led_classdev_register(dev, &led_data->cdev); 168 if (ret < 0) { 169 fwnode_handle_put(child); 170 return ret; 171 } 172 173 led_data->cdev.dev->of_node = dev->of_node; 174 175 out: 176 platform_set_drvdata(pdev, led_data); 177 178 return 0; 179 } 180 181 #ifdef CONFIG_OF 182 static const struct of_device_id of_lt3593_leds_match[] = { 183 { .compatible = "lltc,lt3593", }, 184 {}, 185 }; 186 MODULE_DEVICE_TABLE(of, of_lt3593_leds_match); 187 #endif 188 189 static struct platform_driver lt3593_led_driver = { 190 .probe = lt3593_led_probe, 191 .driver = { 192 .name = "leds-lt3593", 193 .of_match_table = of_match_ptr(of_lt3593_leds_match), 194 }, 195 }; 196 197 module_platform_driver(lt3593_led_driver); 198 199 MODULE_AUTHOR("Daniel Mack <daniel@zonque.org>"); 200 MODULE_DESCRIPTION("LED driver for LT3593 controllers"); 201 MODULE_LICENSE("GPL v2"); 202 MODULE_ALIAS("platform:leds-lt3593"); 203