1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Backlight driver for the Kinetic KTZ8866
4 *
5 * Copyright (C) 2022, 2023 Jianhua Lu <lujianhua000@gmail.com>
6 */
7
8 #include <linux/backlight.h>
9 #include <linux/err.h>
10 #include <linux/gpio/consumer.h>
11 #include <linux/i2c.h>
12 #include <linux/module.h>
13 #include <linux/of.h>
14 #include <linux/regmap.h>
15
16 #define DEFAULT_BRIGHTNESS 1500
17 #define MAX_BRIGHTNESS 2047
18 #define REG_MAX 0x15
19
20 /* reg */
21 #define DEVICE_ID 0x01
22 #define BL_CFG1 0x02
23 #define BL_CFG2 0x03
24 #define BL_BRT_LSB 0x04
25 #define BL_BRT_MSB 0x05
26 #define BL_EN 0x08
27 #define LCD_BIAS_CFG1 0x09
28 #define LCD_BIAS_CFG2 0x0A
29 #define LCD_BIAS_CFG3 0x0B
30 #define LCD_BOOST_CFG 0x0C
31 #define OUTP_CFG 0x0D
32 #define OUTN_CFG 0x0E
33 #define FLAG 0x0F
34 #define BL_OPTION1 0x10
35 #define BL_OPTION2 0x11
36 #define PWM2DIG_LSBs 0x12
37 #define PWM2DIG_MSBs 0x13
38 #define BL_DIMMING 0x14
39 #define PWM_RAMP_TIME 0x15
40
41 /* definition */
42 #define BL_EN_BIT BIT(6)
43 #define LCD_BIAS_EN 0x9F
44 #define PWM_HYST 0x5
45
46 struct ktz8866 {
47 struct i2c_client *client;
48 struct regmap *regmap;
49 bool led_on;
50 struct gpio_desc *enable_gpio;
51 };
52
53 static const struct regmap_config ktz8866_regmap_config = {
54 .reg_bits = 8,
55 .val_bits = 8,
56 .max_register = REG_MAX,
57 };
58
ktz8866_write(struct ktz8866 * ktz,unsigned int reg,unsigned int val)59 static int ktz8866_write(struct ktz8866 *ktz, unsigned int reg,
60 unsigned int val)
61 {
62 return regmap_write(ktz->regmap, reg, val);
63 }
64
ktz8866_update_bits(struct ktz8866 * ktz,unsigned int reg,unsigned int mask,unsigned int val)65 static int ktz8866_update_bits(struct ktz8866 *ktz, unsigned int reg,
66 unsigned int mask, unsigned int val)
67 {
68 return regmap_update_bits(ktz->regmap, reg, mask, val);
69 }
70
ktz8866_backlight_update_status(struct backlight_device * backlight_dev)71 static int ktz8866_backlight_update_status(struct backlight_device *backlight_dev)
72 {
73 struct ktz8866 *ktz = bl_get_data(backlight_dev);
74 unsigned int brightness = backlight_get_brightness(backlight_dev);
75
76 if (!ktz->led_on && brightness > 0) {
77 ktz8866_update_bits(ktz, BL_EN, BL_EN_BIT, BL_EN_BIT);
78 ktz->led_on = true;
79 } else if (brightness == 0) {
80 ktz8866_update_bits(ktz, BL_EN, BL_EN_BIT, 0);
81 ktz->led_on = false;
82 }
83
84 /* Set brightness */
85 ktz8866_write(ktz, BL_BRT_LSB, brightness & 0x7);
86 ktz8866_write(ktz, BL_BRT_MSB, (brightness >> 3) & 0xFF);
87
88 return 0;
89 }
90
91 static const struct backlight_ops ktz8866_backlight_ops = {
92 .options = BL_CORE_SUSPENDRESUME,
93 .update_status = ktz8866_backlight_update_status,
94 };
95
ktz8866_init(struct ktz8866 * ktz)96 static void ktz8866_init(struct ktz8866 *ktz)
97 {
98 unsigned int val = 0;
99
100 if (!of_property_read_u32(ktz->client->dev.of_node, "current-num-sinks", &val))
101 ktz8866_write(ktz, BL_EN, BIT(val) - 1);
102 else
103 /* Enable all 6 current sinks if the number of current sinks isn't specified. */
104 ktz8866_write(ktz, BL_EN, BIT(6) - 1);
105
106 if (!of_property_read_u32(ktz->client->dev.of_node, "kinetic,current-ramp-delay-ms", &val)) {
107 if (val <= 128)
108 ktz8866_write(ktz, BL_CFG2, BIT(7) | (ilog2(val) << 3) | PWM_HYST);
109 else
110 ktz8866_write(ktz, BL_CFG2, BIT(7) | ((5 + val / 64) << 3) | PWM_HYST);
111 }
112
113 if (!of_property_read_u32(ktz->client->dev.of_node, "kinetic,led-enable-ramp-delay-ms", &val)) {
114 if (val == 0)
115 ktz8866_write(ktz, BL_DIMMING, 0);
116 else {
117 unsigned int ramp_off_time = ilog2(val) + 1;
118 unsigned int ramp_on_time = ramp_off_time << 4;
119 ktz8866_write(ktz, BL_DIMMING, ramp_on_time | ramp_off_time);
120 }
121 }
122
123 if (of_property_read_bool(ktz->client->dev.of_node, "kinetic,enable-lcd-bias"))
124 ktz8866_write(ktz, LCD_BIAS_CFG1, LCD_BIAS_EN);
125 }
126
ktz8866_probe(struct i2c_client * client)127 static int ktz8866_probe(struct i2c_client *client)
128 {
129 struct backlight_device *backlight_dev;
130 struct backlight_properties props;
131 struct ktz8866 *ktz;
132 int ret = 0;
133
134 ktz = devm_kzalloc(&client->dev, sizeof(*ktz), GFP_KERNEL);
135 if (!ktz)
136 return -ENOMEM;
137
138 ktz->client = client;
139 ktz->regmap = devm_regmap_init_i2c(client, &ktz8866_regmap_config);
140 if (IS_ERR(ktz->regmap))
141 return dev_err_probe(&client->dev, PTR_ERR(ktz->regmap), "failed to init regmap\n");
142
143 ret = devm_regulator_get_enable(&client->dev, "vddpos");
144 if (ret)
145 return dev_err_probe(&client->dev, ret, "get regulator vddpos failed\n");
146 ret = devm_regulator_get_enable(&client->dev, "vddneg");
147 if (ret)
148 return dev_err_probe(&client->dev, ret, "get regulator vddneg failed\n");
149
150 ktz->enable_gpio = devm_gpiod_get_optional(&client->dev, "enable", GPIOD_OUT_HIGH);
151 if (IS_ERR(ktz->enable_gpio))
152 return PTR_ERR(ktz->enable_gpio);
153
154 memset(&props, 0, sizeof(props));
155 props.type = BACKLIGHT_RAW;
156 props.max_brightness = MAX_BRIGHTNESS;
157 props.brightness = DEFAULT_BRIGHTNESS;
158 props.scale = BACKLIGHT_SCALE_LINEAR;
159
160 backlight_dev = devm_backlight_device_register(&client->dev, "ktz8866-backlight",
161 &client->dev, ktz, &ktz8866_backlight_ops, &props);
162 if (IS_ERR(backlight_dev))
163 return dev_err_probe(&client->dev, PTR_ERR(backlight_dev),
164 "failed to register backlight device\n");
165
166 ktz8866_init(ktz);
167
168 i2c_set_clientdata(client, backlight_dev);
169 backlight_update_status(backlight_dev);
170
171 return 0;
172 }
173
ktz8866_remove(struct i2c_client * client)174 static void ktz8866_remove(struct i2c_client *client)
175 {
176 struct backlight_device *backlight_dev = i2c_get_clientdata(client);
177 backlight_dev->props.brightness = 0;
178 backlight_update_status(backlight_dev);
179 }
180
181 static const struct i2c_device_id ktz8866_ids[] = {
182 { "ktz8866" },
183 {}
184 };
185 MODULE_DEVICE_TABLE(i2c, ktz8866_ids);
186
187 static const struct of_device_id ktz8866_match_table[] = {
188 {
189 .compatible = "kinetic,ktz8866",
190 },
191 {},
192 };
193
194 static struct i2c_driver ktz8866_driver = {
195 .driver = {
196 .name = "ktz8866",
197 .of_match_table = ktz8866_match_table,
198 },
199 .probe = ktz8866_probe,
200 .remove = ktz8866_remove,
201 .id_table = ktz8866_ids,
202 };
203
204 module_i2c_driver(ktz8866_driver);
205
206 MODULE_DESCRIPTION("Kinetic KTZ8866 Backlight Driver");
207 MODULE_AUTHOR("Jianhua Lu <lujianhua000@gmail.com>");
208 MODULE_LICENSE("GPL");
209