1/*
2 * D-Link DIR-685 router I2C-based Touchkeys input driver
3 * Copyright (C) 2017 Linus Walleij <linus.walleij@linaro.org>
4 *
5 * This is a one-off touchkey controller based on the Cypress Semiconductor
6 * CY8C214 MCU with some firmware in its internal 8KB flash. The circuit
7 * board inside the router is named E119921
8 */
9
10#include <linux/module.h>
11#include <linux/i2c.h>
12#include <linux/interrupt.h>
13#include <linux/delay.h>
14#include <linux/input.h>
15#include <linux/slab.h>
16#include <linux/bitops.h>
17
18struct dir685_touchkeys {
19 struct device *dev;
20 struct i2c_client *client;
21 struct input_dev *input;
22 unsigned long cur_key;
23 u16 codes[7];
24};
25
26static irqreturn_t dir685_tk_irq_thread(int irq, void *data)
27{
28 struct dir685_touchkeys *tk = data;
29 const int num_bits = min_t(int, ARRAY_SIZE(tk->codes), 16);
30 unsigned long changed;
31 u8 buf[6];
32 unsigned long key;
33 int i;
34 int err;
35
36 memset(buf, 0, sizeof(buf));
37 err = i2c_master_recv(tk->client, buf, sizeof(buf));
38 if (err != sizeof(buf)) {
39 dev_err(tk->dev, "short read %d\n", err);
40 return IRQ_HANDLED;
41 }
42
43 dev_dbg(tk->dev, "IN: %*ph\n", (int)sizeof(buf), buf);
44 key = be16_to_cpup((__be16 *) &buf[4]);
45
46 /* Figure out if any bits went high or low since last message */
47 changed = tk->cur_key ^ key;
48 for_each_set_bit(i, &changed, num_bits) {
49 dev_dbg(tk->dev, "key %d is %s\n", i,
50 test_bit(i, &key) ? "down" : "up");
51 input_report_key(tk->input, tk->codes[i], test_bit(i, &key));
52 }
53
54 /* Store currently down keys */
55 tk->cur_key = key;
56 input_sync(tk->input);
57
58 return IRQ_HANDLED;
59}
60
61static int dir685_tk_probe(struct i2c_client *client,
62 const struct i2c_device_id *id)
63{
64 struct dir685_touchkeys *tk;
65 struct device *dev = &client->dev;
66 u8 bl_data[] = { 0xa7, 0x40 };
67 int err;
68 int i;
69
70 tk = devm_kzalloc(&client->dev, sizeof(*tk), GFP_KERNEL);
71 if (!tk)
72 return -ENOMEM;
73
74 tk->input = devm_input_allocate_device(dev);
75 if (!tk->input)
76 return -ENOMEM;
77
78 tk->client = client;
79 tk->dev = dev;
80
81 tk->input->keycodesize = sizeof(u16);
82 tk->input->keycodemax = ARRAY_SIZE(tk->codes);
83 tk->input->keycode = tk->codes;
84 tk->codes[0] = KEY_UP;
85 tk->codes[1] = KEY_DOWN;
86 tk->codes[2] = KEY_LEFT;
87 tk->codes[3] = KEY_RIGHT;
88 tk->codes[4] = KEY_ENTER;
89 tk->codes[5] = KEY_WPS_BUTTON;
90 /*
91 * This key appears in the vendor driver, but I have
92 * not been able to activate it.
93 */
94 tk->codes[6] = KEY_RESERVED;
95
96 __set_bit(EV_KEY, tk->input->evbit);
97 for (i = 0; i < ARRAY_SIZE(tk->codes); i++)
98 __set_bit(tk->codes[i], tk->input->keybit);
99 __clear_bit(KEY_RESERVED, tk->input->keybit);
100
101 tk->input->name = "D-Link DIR-685 touchkeys";
102 tk->input->id.bustype = BUS_I2C;
103
104 err = input_register_device(tk->input);
105 if (err)
106 return err;
107
108 /* Set the brightness to max level */
109 err = i2c_master_send(client, bl_data, sizeof(bl_data));
110 if (err != sizeof(bl_data))
111 dev_warn(tk->dev, "error setting brightness level\n");
112
113 if (!client->irq) {
114 dev_err(dev, "no IRQ on the I2C device\n");
115 return -ENODEV;
116 }
117 err = devm_request_threaded_irq(dev, client->irq,
118 NULL, dir685_tk_irq_thread,
119 IRQF_ONESHOT,
120 "dir685-tk", tk);
121 if (err) {
122 dev_err(dev, "can't request IRQ\n");
123 return err;
124 }
125
126 return 0;
127}
128
129static const struct i2c_device_id dir685_tk_id[] = {
130 { "dir685tk", 0 },
131 { }
132};
133MODULE_DEVICE_TABLE(i2c, dir685_tk_id);
134
135#ifdef CONFIG_OF
136static const struct of_device_id dir685_tk_of_match[] = {
137 { .compatible = "dlink,dir685-touchkeys" },
138 {},
139};
140MODULE_DEVICE_TABLE(of, dir685_tk_of_match);
141#endif
142
143static struct i2c_driver dir685_tk_i2c_driver = {
144 .driver = {
145 .name = "dlin-dir685-touchkeys",
146 .of_match_table = of_match_ptr(dir685_tk_of_match),
147 },
148 .probe = dir685_tk_probe,
149 .id_table = dir685_tk_id,
150};
151module_i2c_driver(dir685_tk_i2c_driver);
152
153MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>");
154MODULE_DESCRIPTION("D-Link DIR-685 touchkeys driver");
155MODULE_LICENSE("GPL");
156