i2c-hid-of-elan.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Driver for Elan touchscreens that use the i2c-hid protocol.
  4 *
  5 * Copyright 2020 Google LLC
  6 */
  7
  8#include <linux/delay.h>
  9#include <linux/device.h>
 10#include <linux/gpio/consumer.h>
 11#include <linux/hid.h>
 12#include <linux/i2c.h>
 13#include <linux/kernel.h>
 14#include <linux/module.h>
 15#include <linux/of.h>
 16#include <linux/pm.h>
 17#include <linux/regulator/consumer.h>
 18
 19#include "i2c-hid.h"
 20
 21struct elan_i2c_hid_chip_data {
 22	unsigned int post_gpio_reset_on_delay_ms;
 23	unsigned int post_gpio_reset_off_delay_ms;
 24	unsigned int post_power_delay_ms;
 25	u16 hid_descriptor_address;
 26	const char *main_supply_name;
 27	bool power_after_backlight;
 28};
 29
 30struct i2c_hid_of_elan {
 31	struct i2chid_ops ops;
 32
 33	struct regulator *vcc33;
 34	struct regulator *vccio;
 35	struct gpio_desc *reset_gpio;
 36	bool no_reset_on_power_off;
 37	const struct elan_i2c_hid_chip_data *chip_data;
 38};
 39
 40static int elan_i2c_hid_power_up(struct i2chid_ops *ops)
 41{
 42	struct i2c_hid_of_elan *ihid_elan =
 43		container_of(ops, struct i2c_hid_of_elan, ops);
 44	int ret;
 45
 46	gpiod_set_value_cansleep(ihid_elan->reset_gpio, 1);
 47
 48	if (ihid_elan->vcc33) {
 49		ret = regulator_enable(ihid_elan->vcc33);
 50		if (ret)
 51			goto err_deassert_reset;
 52	}
 53
 54	ret = regulator_enable(ihid_elan->vccio);
 55	if (ret)
 56		goto err_disable_vcc33;
 57
 58	if (ihid_elan->chip_data->post_power_delay_ms)
 59		msleep(ihid_elan->chip_data->post_power_delay_ms);
 60
 61	gpiod_set_value_cansleep(ihid_elan->reset_gpio, 0);
 62	if (ihid_elan->chip_data->post_gpio_reset_on_delay_ms)
 63		msleep(ihid_elan->chip_data->post_gpio_reset_on_delay_ms);
 64
 65	return 0;
 66
 67err_disable_vcc33:
 68	if (ihid_elan->vcc33)
 69		regulator_disable(ihid_elan->vcc33);
 70err_deassert_reset:
 71	if (ihid_elan->no_reset_on_power_off)
 72		gpiod_set_value_cansleep(ihid_elan->reset_gpio, 0);
 73
 74	return ret;
 75}
 76
 77static void elan_i2c_hid_power_down(struct i2chid_ops *ops)
 78{
 79	struct i2c_hid_of_elan *ihid_elan =
 80		container_of(ops, struct i2c_hid_of_elan, ops);
 81
 82	/*
 83	 * Do not assert reset when the hardware allows for it to remain
 84	 * deasserted regardless of the state of the (shared) power supply to
 85	 * avoid wasting power when the supply is left on.
 86	 */
 87	if (!ihid_elan->no_reset_on_power_off)
 88		gpiod_set_value_cansleep(ihid_elan->reset_gpio, 1);
 89
 90	if (ihid_elan->chip_data->post_gpio_reset_off_delay_ms)
 91		msleep(ihid_elan->chip_data->post_gpio_reset_off_delay_ms);
 92
 93	regulator_disable(ihid_elan->vccio);
 94	if (ihid_elan->vcc33)
 95		regulator_disable(ihid_elan->vcc33);
 96}
 97
 98static int i2c_hid_of_elan_probe(struct i2c_client *client)
 99{
100	struct i2c_hid_of_elan *ihid_elan;
101	int ret;
102	u32 quirks = 0;
103
104	ihid_elan = devm_kzalloc(&client->dev, sizeof(*ihid_elan), GFP_KERNEL);
105	if (!ihid_elan)
106		return -ENOMEM;
107
108	ihid_elan->ops.power_up = elan_i2c_hid_power_up;
109	ihid_elan->ops.power_down = elan_i2c_hid_power_down;
110
111	/* Start out with reset asserted */
112	ihid_elan->reset_gpio =
113		devm_gpiod_get_optional(&client->dev, "reset", GPIOD_OUT_HIGH);
114	if (IS_ERR(ihid_elan->reset_gpio))
115		return PTR_ERR(ihid_elan->reset_gpio);
116
117	ihid_elan->no_reset_on_power_off = of_property_read_bool(client->dev.of_node,
118						"no-reset-on-power-off");
119
120	ihid_elan->vccio = devm_regulator_get(&client->dev, "vccio");
121	if (IS_ERR(ihid_elan->vccio)) {
122		ret = PTR_ERR(ihid_elan->vccio);
123		goto err_deassert_reset;
124	}
125
126	ihid_elan->chip_data = device_get_match_data(&client->dev);
127
128	if (ihid_elan->chip_data->main_supply_name) {
129		ihid_elan->vcc33 = devm_regulator_get(&client->dev,
130						      ihid_elan->chip_data->main_supply_name);
131		if (IS_ERR(ihid_elan->vcc33)) {
132			ret = PTR_ERR(ihid_elan->vcc33);
133			goto err_deassert_reset;
134		}
135	}
136
137	if (ihid_elan->chip_data->power_after_backlight)
138		quirks = HID_QUIRK_POWER_ON_AFTER_BACKLIGHT;
139
140	ret = i2c_hid_core_probe(client, &ihid_elan->ops,
141				 ihid_elan->chip_data->hid_descriptor_address,
142				 quirks);
143	if (ret)
144		goto err_deassert_reset;
145
146	return 0;
147
148err_deassert_reset:
149	if (ihid_elan->no_reset_on_power_off)
150		gpiod_set_value_cansleep(ihid_elan->reset_gpio, 0);
151
152	return ret;
153}
154
155static const struct elan_i2c_hid_chip_data elan_ekth6915_chip_data = {
156	.post_power_delay_ms = 1,
157	.post_gpio_reset_on_delay_ms = 300,
158	.hid_descriptor_address = 0x0001,
159	.main_supply_name = "vcc33",
160	.power_after_backlight = true,
161};
162
163static const struct elan_i2c_hid_chip_data elan_ekth6a12nay_chip_data = {
164	.post_power_delay_ms = 10,
165	.post_gpio_reset_on_delay_ms = 300,
166	.hid_descriptor_address = 0x0001,
167	.main_supply_name = "vcc33",
168	.power_after_backlight = true,
169};
170
171static const struct elan_i2c_hid_chip_data focaltech_ft8112_chip_data = {
172	.post_power_delay_ms = 10,
173	.post_gpio_reset_on_delay_ms = 150,
174	.hid_descriptor_address = 0x0001,
175	.main_supply_name = "vcc33",
176};
177
178static const struct elan_i2c_hid_chip_data ilitek_ili9882t_chip_data = {
179	.post_power_delay_ms = 1,
180	.post_gpio_reset_on_delay_ms = 200,
181	.post_gpio_reset_off_delay_ms = 65,
182	.hid_descriptor_address = 0x0001,
183	/*
184	 * this touchscreen is tightly integrated with the panel and assumes
185	 * that the relevant power rails (other than the IO rail) have already
186	 * been turned on by the panel driver because we're a panel follower.
187	 */
188	.main_supply_name = NULL,
189};
190
191static const struct elan_i2c_hid_chip_data ilitek_ili2901_chip_data = {
192	.post_power_delay_ms = 10,
193	.post_gpio_reset_on_delay_ms = 100,
194	.hid_descriptor_address = 0x0001,
195	.main_supply_name = "vcc33",
196};
197
198static const struct of_device_id elan_i2c_hid_of_match[] = {
199	{ .compatible = "elan,ekth6915", .data = &elan_ekth6915_chip_data },
200	{ .compatible = "elan,ekth6a12nay", .data = &elan_ekth6a12nay_chip_data },
201	{ .compatible = "focaltech,ft8112", .data = &focaltech_ft8112_chip_data },
202	{ .compatible = "ilitek,ili9882t", .data = &ilitek_ili9882t_chip_data },
203	{ .compatible = "ilitek,ili2901", .data = &ilitek_ili2901_chip_data },
204	{ }
205};
206MODULE_DEVICE_TABLE(of, elan_i2c_hid_of_match);
207
208static struct i2c_driver elan_i2c_hid_ts_driver = {
209	.driver = {
210		.name	= "i2c_hid_of_elan",
211		.pm	= &i2c_hid_core_pm,
212		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
213		.of_match_table = of_match_ptr(elan_i2c_hid_of_match),
214	},
215	.probe		= i2c_hid_of_elan_probe,
216	.remove		= i2c_hid_core_remove,
217	.shutdown	= i2c_hid_core_shutdown,
218};
219module_i2c_driver(elan_i2c_hid_ts_driver);
220
221MODULE_AUTHOR("Douglas Anderson <dianders@chromium.org>");
222MODULE_DESCRIPTION("Elan i2c-hid touchscreen driver");
223MODULE_LICENSE("GPL");