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