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
as3668_channel_mode_set(struct as3668_led * led,u8 mode)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
as3668_brightness_get(struct led_classdev * cdev)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
as3668_brightness_set(struct led_classdev * cdev,enum led_brightness brightness)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
as3668_dt_init(struct as3668 * as3668)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
as3668_probe(struct i2c_client * client)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
as3668_remove(struct i2c_client * client)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