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_delay_ms;
22 unsigned int post_power_delay_ms;
23 u16 hid_descriptor_address;
24 };
25
26 struct i2c_hid_of_elan {
27 struct i2chid_ops ops;
28
29 struct regulator *vcc33;
30 struct regulator *vccio;
31 struct gpio_desc *reset_gpio;
32 const struct elan_i2c_hid_chip_data *chip_data;
33 };
34
elan_i2c_hid_power_up(struct i2chid_ops * ops)35 static int elan_i2c_hid_power_up(struct i2chid_ops *ops)
36 {
37 struct i2c_hid_of_elan *ihid_elan =
38 container_of(ops, struct i2c_hid_of_elan, ops);
39 int ret;
40
41 ret = regulator_enable(ihid_elan->vcc33);
42 if (ret)
43 return ret;
44
45 ret = regulator_enable(ihid_elan->vccio);
46 if (ret) {
47 regulator_disable(ihid_elan->vcc33);
48 return ret;
49 }
50
51 if (ihid_elan->chip_data->post_power_delay_ms)
52 msleep(ihid_elan->chip_data->post_power_delay_ms);
53
54 gpiod_set_value_cansleep(ihid_elan->reset_gpio, 0);
55 if (ihid_elan->chip_data->post_gpio_reset_delay_ms)
56 msleep(ihid_elan->chip_data->post_gpio_reset_delay_ms);
57
58 return 0;
59 }
60
elan_i2c_hid_power_down(struct i2chid_ops * ops)61 static void elan_i2c_hid_power_down(struct i2chid_ops *ops)
62 {
63 struct i2c_hid_of_elan *ihid_elan =
64 container_of(ops, struct i2c_hid_of_elan, ops);
65
66 gpiod_set_value_cansleep(ihid_elan->reset_gpio, 1);
67 regulator_disable(ihid_elan->vccio);
68 regulator_disable(ihid_elan->vcc33);
69 }
70
i2c_hid_of_elan_probe(struct i2c_client * client,const struct i2c_device_id * id)71 static int i2c_hid_of_elan_probe(struct i2c_client *client,
72 const struct i2c_device_id *id)
73 {
74 struct i2c_hid_of_elan *ihid_elan;
75
76 ihid_elan = devm_kzalloc(&client->dev, sizeof(*ihid_elan), GFP_KERNEL);
77 if (!ihid_elan)
78 return -ENOMEM;
79
80 ihid_elan->ops.power_up = elan_i2c_hid_power_up;
81 ihid_elan->ops.power_down = elan_i2c_hid_power_down;
82
83 /* Start out with reset asserted */
84 ihid_elan->reset_gpio =
85 devm_gpiod_get_optional(&client->dev, "reset", GPIOD_OUT_HIGH);
86 if (IS_ERR(ihid_elan->reset_gpio))
87 return PTR_ERR(ihid_elan->reset_gpio);
88
89 ihid_elan->vccio = devm_regulator_get(&client->dev, "vccio");
90 if (IS_ERR(ihid_elan->vccio))
91 return PTR_ERR(ihid_elan->vccio);
92
93 ihid_elan->vcc33 = devm_regulator_get(&client->dev, "vcc33");
94 if (IS_ERR(ihid_elan->vcc33))
95 return PTR_ERR(ihid_elan->vcc33);
96
97 ihid_elan->chip_data = device_get_match_data(&client->dev);
98
99 return i2c_hid_core_probe(client, &ihid_elan->ops,
100 ihid_elan->chip_data->hid_descriptor_address, 0);
101 }
102
103 static const struct elan_i2c_hid_chip_data elan_ekth6915_chip_data = {
104 .post_power_delay_ms = 1,
105 .post_gpio_reset_delay_ms = 300,
106 .hid_descriptor_address = 0x0001,
107 };
108
109 static const struct of_device_id elan_i2c_hid_of_match[] = {
110 { .compatible = "elan,ekth6915", .data = &elan_ekth6915_chip_data },
111 { }
112 };
113 MODULE_DEVICE_TABLE(of, elan_i2c_hid_of_match);
114
115 static struct i2c_driver elan_i2c_hid_ts_driver = {
116 .driver = {
117 .name = "i2c_hid_of_elan",
118 .pm = &i2c_hid_core_pm,
119 .probe_type = PROBE_PREFER_ASYNCHRONOUS,
120 .of_match_table = of_match_ptr(elan_i2c_hid_of_match),
121 },
122 .probe = i2c_hid_of_elan_probe,
123 .remove = i2c_hid_core_remove,
124 .shutdown = i2c_hid_core_shutdown,
125 };
126 module_i2c_driver(elan_i2c_hid_ts_driver);
127
128 MODULE_AUTHOR("Douglas Anderson <dianders@chromium.org>");
129 MODULE_DESCRIPTION("Elan i2c-hid touchscreen driver");
130 MODULE_LICENSE("GPL");
131
