1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Copyright (C) 2020 Marek Vasut <marex@denx.de>
  4 *
  5 * Based on rpi_touchscreen.c by Eric Anholt <eric@anholt.net>
  6 */
  7
  8#include <linux/backlight.h>
  9#include <linux/err.h>
 10#include <linux/gpio.h>
 11#include <linux/i2c.h>
 12#include <linux/init.h>
 13#include <linux/interrupt.h>
 14#include <linux/module.h>
 15#include <linux/regmap.h>
 16#include <linux/regulator/driver.h>
 17#include <linux/regulator/machine.h>
 18#include <linux/regulator/of_regulator.h>
 19#include <linux/slab.h>
 20
 21/* I2C registers of the Atmel microcontroller. */
 22#define REG_ID		0x80
 23#define REG_PORTA	0x81
 24#define REG_PORTA_HF	BIT(2)
 25#define REG_PORTA_VF	BIT(3)
 26#define REG_PORTB	0x82
 27#define REG_POWERON	0x85
 28#define REG_PWM		0x86
 29
 30static const struct regmap_config attiny_regmap_config = {
 31	.reg_bits = 8,
 32	.val_bits = 8,
 33	.max_register = REG_PWM,
 34	.cache_type = REGCACHE_NONE,
 35};
 36
 37static int attiny_lcd_power_enable(struct regulator_dev *rdev)
 38{
 39	unsigned int data;
 40
 41	regmap_write(rdev->regmap, REG_POWERON, 1);
 42	/* Wait for nPWRDWN to go low to indicate poweron is done. */
 43	regmap_read_poll_timeout(rdev->regmap, REG_PORTB, data,
 44					data & BIT(0), 10, 1000000);
 45
 46	/* Default to the same orientation as the closed source
 47	 * firmware used for the panel.  Runtime rotation
 48	 * configuration will be supported using VC4's plane
 49	 * orientation bits.
 50	 */
 51	regmap_write(rdev->regmap, REG_PORTA, BIT(2));
 52
 53	return 0;
 54}
 55
 56static int attiny_lcd_power_disable(struct regulator_dev *rdev)
 57{
 58	regmap_write(rdev->regmap, REG_PWM, 0);
 59	regmap_write(rdev->regmap, REG_POWERON, 0);
 60	udelay(1);
 61	return 0;
 62}
 63
 64static int attiny_lcd_power_is_enabled(struct regulator_dev *rdev)
 65{
 66	unsigned int data;
 67	int ret;
 68
 69	ret = regmap_read(rdev->regmap, REG_POWERON, &data);
 70	if (ret < 0)
 71		return ret;
 72
 73	if (!(data & BIT(0)))
 74		return 0;
 75
 76	ret = regmap_read(rdev->regmap, REG_PORTB, &data);
 77	if (ret < 0)
 78		return ret;
 79
 80	return data & BIT(0);
 81}
 82
 83static const struct regulator_init_data attiny_regulator_default = {
 84	.constraints = {
 85		.valid_ops_mask = REGULATOR_CHANGE_STATUS,
 86	},
 87};
 88
 89static const struct regulator_ops attiny_regulator_ops = {
 90	.enable = attiny_lcd_power_enable,
 91	.disable = attiny_lcd_power_disable,
 92	.is_enabled = attiny_lcd_power_is_enabled,
 93};
 94
 95static const struct regulator_desc attiny_regulator = {
 96	.name	= "tc358762-power",
 97	.ops	= &attiny_regulator_ops,
 98	.type	= REGULATOR_VOLTAGE,
 99	.owner	= THIS_MODULE,
100};
101
102static int attiny_update_status(struct backlight_device *bl)
103{
104	struct regmap *regmap = bl_get_data(bl);
105	int brightness = bl->props.brightness;
106
107	if (bl->props.power != FB_BLANK_UNBLANK ||
108	    bl->props.fb_blank != FB_BLANK_UNBLANK)
109		brightness = 0;
110
111	return regmap_write(regmap, REG_PWM, brightness);
112}
113
114static int attiny_get_brightness(struct backlight_device *bl)
115{
116	struct regmap *regmap = bl_get_data(bl);
117	int ret, brightness;
118
119	ret = regmap_read(regmap, REG_PWM, &brightness);
120	if (ret)
121		return ret;
122
123	return brightness;
124}
125
126static const struct backlight_ops attiny_bl = {
127	.update_status	= attiny_update_status,
128	.get_brightness	= attiny_get_brightness,
129};
130
131/*
132 * I2C driver interface functions
133 */
134static int attiny_i2c_probe(struct i2c_client *i2c,
135		const struct i2c_device_id *id)
136{
137	struct backlight_properties props = { };
138	struct regulator_config config = { };
139	struct backlight_device *bl;
140	struct regulator_dev *rdev;
141	struct regmap *regmap;
142	unsigned int data;
143	int ret;
144
145	regmap = devm_regmap_init_i2c(i2c, &attiny_regmap_config);
146	if (IS_ERR(regmap)) {
147		ret = PTR_ERR(regmap);
148		dev_err(&i2c->dev, "Failed to allocate register map: %d\n",
149			ret);
150		return ret;
151	}
152
153	ret = regmap_read(regmap, REG_ID, &data);
154	if (ret < 0) {
155		dev_err(&i2c->dev, "Failed to read REG_ID reg: %d\n", ret);
156		return ret;
157	}
158
159	switch (data) {
160	case 0xde: /* ver 1 */
161	case 0xc3: /* ver 2 */
162		break;
163	default:
164		dev_err(&i2c->dev, "Unknown Atmel firmware revision: 0x%02x\n", data);
165		return -ENODEV;
166	}
167
168	regmap_write(regmap, REG_POWERON, 0);
169	mdelay(1);
170
171	config.dev = &i2c->dev;
172	config.regmap = regmap;
173	config.of_node = i2c->dev.of_node;
174	config.init_data = &attiny_regulator_default;
175
176	rdev = devm_regulator_register(&i2c->dev, &attiny_regulator, &config);
177	if (IS_ERR(rdev)) {
178		dev_err(&i2c->dev, "Failed to register ATTINY regulator\n");
179		return PTR_ERR(rdev);
180	}
181
182	props.type = BACKLIGHT_RAW;
183	props.max_brightness = 0xff;
184	bl = devm_backlight_device_register(&i2c->dev,
185					    "7inch-touchscreen-panel-bl",
186					    &i2c->dev, regmap, &attiny_bl,
187					    &props);
188	if (IS_ERR(bl))
189		return PTR_ERR(bl);
190
191	bl->props.brightness = 0xff;
192
193	return 0;
194}
195
196static const struct of_device_id attiny_dt_ids[] = {
197	{ .compatible = "raspberrypi,7inch-touchscreen-panel-regulator" },
198	{},
199};
200MODULE_DEVICE_TABLE(of, attiny_dt_ids);
201
202static struct i2c_driver attiny_regulator_driver = {
203	.driver = {
204		.name = "rpi_touchscreen_attiny",
205		.of_match_table = of_match_ptr(attiny_dt_ids),
206	},
207	.probe = attiny_i2c_probe,
208};
209
210module_i2c_driver(attiny_regulator_driver);
211
212MODULE_AUTHOR("Marek Vasut <marex@denx.de>");
213MODULE_DESCRIPTION("Regulator device driver for Raspberry Pi 7-inch touchscreen");
214MODULE_LICENSE("GPL v2");