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
elan_i2c_hid_power_up(struct i2chid_ops * ops)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
elan_i2c_hid_power_down(struct i2chid_ops * ops)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
i2c_hid_of_elan_probe(struct i2c_client * client)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