ktz8866.c

  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
 46struct ktz8866 {
 47	struct i2c_client *client;
 48	struct regmap *regmap;
 49	bool led_on;
 50	struct gpio_desc *enable_gpio;
 51};
 52
 53static const struct regmap_config ktz8866_regmap_config = {
 54	.reg_bits = 8,
 55	.val_bits = 8,
 56	.max_register = REG_MAX,
 57};
 58
 59static int ktz8866_write(struct ktz8866 *ktz, unsigned int reg,
 60			 unsigned int val)
 61{
 62	return regmap_write(ktz->regmap, reg, val);
 63}
 64
 65static 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
 71static 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
 91static const struct backlight_ops ktz8866_backlight_ops = {
 92	.options = BL_CORE_SUSPENDRESUME,
 93	.update_status = ktz8866_backlight_update_status,
 94};
 95
 96static 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
127static 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
174static 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
181static const struct i2c_device_id ktz8866_ids[] = {
182	{ "ktz8866" },
183	{}
184};
185MODULE_DEVICE_TABLE(i2c, ktz8866_ids);
186
187static const struct of_device_id ktz8866_match_table[] = {
188	{
189		.compatible = "kinetic,ktz8866",
190	},
191	{},
192};
193MODULE_DEVICE_TABLE(of, ktz8866_match_table);
194
195static struct i2c_driver ktz8866_driver = {
196	.driver = {
197		.name = "ktz8866",
198		.of_match_table = ktz8866_match_table,
199	},
200	.probe = ktz8866_probe,
201	.remove = ktz8866_remove,
202	.id_table = ktz8866_ids,
203};
204
205module_i2c_driver(ktz8866_driver);
206
207MODULE_DESCRIPTION("Kinetic KTZ8866 Backlight Driver");
208MODULE_AUTHOR("Jianhua Lu <lujianhua000@gmail.com>");
209MODULE_LICENSE("GPL");