1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Osram AMS AS3668 LED Driver IC 4 * 5 * Copyright (C) 2025 Lukas Timmermann <linux@timmermann.space> 6 */ 7 8 #include <linux/bitfield.h> 9 #include <linux/i2c.h> 10 #include <linux/leds.h> 11 #include <linux/module.h> 12 #include <linux/uleds.h> 13 14 #define AS3668_MAX_LEDS 4 15 16 /* Chip Ident */ 17 18 #define AS3668_CHIP_ID1_REG 0x3e 19 #define AS3668_CHIP_ID 0xa5 20 21 /* Current Control */ 22 23 #define AS3668_CURR_MODE_REG 0x01 24 #define AS3668_CURR_MODE_OFF 0x0 25 #define AS3668_CURR_MODE_ON 0x1 26 #define AS3668_CURR1_MODE_MASK GENMASK(1, 0) 27 #define AS3668_CURR2_MODE_MASK GENMASK(3, 2) 28 #define AS3668_CURR3_MODE_MASK GENMASK(5, 4) 29 #define AS3668_CURR4_MODE_MASK GENMASK(7, 6) 30 #define AS3668_CURR1_REG 0x02 31 #define AS3668_CURR2_REG 0x03 32 #define AS3668_CURR3_REG 0x04 33 #define AS3668_CURR4_REG 0x05 34 35 #define AS3668_CURR_MODE_PACK(mode) (((mode) << 0) | \ 36 ((mode) << 2) | \ 37 ((mode) << 4) | \ 38 ((mode) << 6)) 39 40 struct as3668_led { 41 struct led_classdev cdev; 42 struct as3668 *chip; 43 struct fwnode_handle *fwnode; 44 u8 mode_mask; 45 u8 current_reg; 46 }; 47 48 struct as3668 { 49 struct i2c_client *client; 50 struct as3668_led leds[AS3668_MAX_LEDS]; 51 }; 52 53 static int as3668_channel_mode_set(struct as3668_led *led, u8 mode) 54 { 55 int ret; 56 u8 channel_modes; 57 58 ret = i2c_smbus_read_byte_data(led->chip->client, AS3668_CURR_MODE_REG); 59 if (ret < 0) { 60 dev_err(led->cdev.dev, "failed to read channel modes\n"); 61 return ret; 62 } 63 channel_modes = (u8)ret; 64 65 channel_modes &= ~led->mode_mask; 66 channel_modes |= led->mode_mask & (AS3668_CURR_MODE_PACK(mode)); 67 68 return i2c_smbus_write_byte_data(led->chip->client, AS3668_CURR_MODE_REG, channel_modes); 69 } 70 71 static enum led_brightness as3668_brightness_get(struct led_classdev *cdev) 72 { 73 struct as3668_led *led = container_of(cdev, struct as3668_led, cdev); 74 75 return i2c_smbus_read_byte_data(led->chip->client, led->current_reg); 76 } 77 78 static void as3668_brightness_set(struct led_classdev *cdev, enum led_brightness brightness) 79 { 80 struct as3668_led *led = container_of(cdev, struct as3668_led, cdev); 81 int err; 82 83 err = as3668_channel_mode_set(led, !!brightness); 84 if (err) 85 dev_err(cdev->dev, "failed to set channel mode: %d\n", err); 86 87 err = i2c_smbus_write_byte_data(led->chip->client, led->current_reg, brightness); 88 if (err) 89 dev_err(cdev->dev, "failed to set brightness: %d\n", err); 90 } 91 92 static int as3668_dt_init(struct as3668 *as3668) 93 { 94 struct device *dev = &as3668->client->dev; 95 struct as3668_led *led; 96 struct led_init_data init_data = {}; 97 int err; 98 u32 reg; 99 100 for_each_available_child_of_node_scoped(dev_of_node(dev), child) { 101 err = of_property_read_u32(child, "reg", ®); 102 if (err) 103 return dev_err_probe(dev, err, "failed to read 'reg' property"); 104 105 if (reg < 0 || reg >= AS3668_MAX_LEDS) 106 return dev_err_probe(dev, -EINVAL, 107 "unsupported LED: %d\n", reg); 108 109 led = &as3668->leds[reg]; 110 led->fwnode = of_fwnode_handle(child); 111 112 led->current_reg = reg + AS3668_CURR1_REG; 113 led->mode_mask = AS3668_CURR1_MODE_MASK << (reg * 2); 114 led->chip = as3668; 115 116 led->cdev.max_brightness = U8_MAX; 117 led->cdev.brightness_get = as3668_brightness_get; 118 led->cdev.brightness_set = as3668_brightness_set; 119 120 init_data.fwnode = led->fwnode; 121 init_data.default_label = ":"; 122 123 err = devm_led_classdev_register_ext(dev, &led->cdev, &init_data); 124 if (err) 125 return dev_err_probe(dev, err, "failed to register LED %d\n", reg); 126 } 127 128 return 0; 129 } 130 131 static int as3668_probe(struct i2c_client *client) 132 { 133 struct as3668 *as3668; 134 int err; 135 u8 chip_id; 136 137 chip_id = i2c_smbus_read_byte_data(client, AS3668_CHIP_ID1_REG); 138 if (chip_id != AS3668_CHIP_ID) 139 return dev_err_probe(&client->dev, -ENODEV, 140 "expected chip ID 0x%02x, got 0x%02x\n", 141 AS3668_CHIP_ID, chip_id); 142 143 as3668 = devm_kzalloc(&client->dev, sizeof(*as3668), GFP_KERNEL); 144 if (!as3668) 145 return -ENOMEM; 146 147 as3668->client = client; 148 149 err = as3668_dt_init(as3668); 150 if (err) 151 return err; 152 153 /* Set all four channel modes to 'off' */ 154 err = i2c_smbus_write_byte_data(client, AS3668_CURR_MODE_REG, 155 FIELD_PREP(AS3668_CURR1_MODE_MASK, AS3668_CURR_MODE_OFF) | 156 FIELD_PREP(AS3668_CURR2_MODE_MASK, AS3668_CURR_MODE_OFF) | 157 FIELD_PREP(AS3668_CURR3_MODE_MASK, AS3668_CURR_MODE_OFF) | 158 FIELD_PREP(AS3668_CURR4_MODE_MASK, AS3668_CURR_MODE_OFF)); 159 160 /* Set initial currents to 0mA */ 161 err |= i2c_smbus_write_byte_data(client, AS3668_CURR1_REG, 0); 162 err |= i2c_smbus_write_byte_data(client, AS3668_CURR2_REG, 0); 163 err |= i2c_smbus_write_byte_data(client, AS3668_CURR3_REG, 0); 164 err |= i2c_smbus_write_byte_data(client, AS3668_CURR4_REG, 0); 165 166 if (err) 167 return dev_err_probe(&client->dev, -EIO, "failed to set zero initial current levels\n"); 168 169 return 0; 170 } 171 172 static void as3668_remove(struct i2c_client *client) 173 { 174 i2c_smbus_write_byte_data(client, AS3668_CURR_MODE_REG, 0); 175 } 176 177 static const struct i2c_device_id as3668_idtable[] = { 178 { "as3668" }, 179 { } 180 }; 181 MODULE_DEVICE_TABLE(i2c, as3668_idtable); 182 183 static const struct of_device_id as3668_match_table[] = { 184 { .compatible = "ams,as3668" }, 185 { } 186 }; 187 MODULE_DEVICE_TABLE(of, as3668_match_table); 188 189 static struct i2c_driver as3668_driver = { 190 .driver = { 191 .name = "leds_as3668", 192 .of_match_table = as3668_match_table, 193 }, 194 .probe = as3668_probe, 195 .remove = as3668_remove, 196 .id_table = as3668_idtable, 197 }; 198 module_i2c_driver(as3668_driver); 199 200 MODULE_AUTHOR("Lukas Timmermann <linux@timmermann.space>"); 201 MODULE_DESCRIPTION("AS3668 LED driver"); 202 MODULE_LICENSE("GPL"); 203