1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * D-Link DIR-685 router I2C-based Touchkeys input driver
4 * Copyright (C) 2017 Linus Walleij <linus.walleij@linaro.org>
5 *
6 * This is a one-off touchkey controller based on the Cypress Semiconductor
7 * CY8C214 MCU with some firmware in its internal 8KB flash. The circuit
8 * board inside the router is named E119921
9 */
10
11#include <linux/module.h>
12#include <linux/i2c.h>
13#include <linux/interrupt.h>
14#include <linux/delay.h>
15#include <linux/input.h>
16#include <linux/slab.h>
17#include <linux/bitops.h>
18
19struct dir685_touchkeys {
20	struct device		*dev;
21	struct i2c_client	*client;
22	struct input_dev	*input;
23	unsigned long		cur_key;
24	u16			codes[7];
25};
26
27static irqreturn_t dir685_tk_irq_thread(int irq, void *data)
28{
29	struct dir685_touchkeys *tk = data;
30	const int num_bits = min_t(int, ARRAY_SIZE(tk->codes), 16);
31	unsigned long changed;
32	u8 buf[6];
33	unsigned long key;
34	int i;
35	int err;
36
37	memset(buf, 0, sizeof(buf));
38	err = i2c_master_recv(tk->client, buf, sizeof(buf));
39	if (err != sizeof(buf)) {
40		dev_err(tk->dev, "short read %d\n", err);
41		return IRQ_HANDLED;
42	}
43
44	dev_dbg(tk->dev, "IN: %*ph\n", (int)sizeof(buf), buf);
45	key = be16_to_cpup((__be16 *) &buf[4]);
46
47	/* Figure out if any bits went high or low since last message */
48	changed = tk->cur_key ^ key;
49	for_each_set_bit(i, &changed, num_bits) {
50		dev_dbg(tk->dev, "key %d is %s\n", i,
51			test_bit(i, &key) ? "down" : "up");
52		input_report_key(tk->input, tk->codes[i], test_bit(i, &key));
53	}
54
55	/* Store currently down keys */
56	tk->cur_key = key;
57	input_sync(tk->input);
58
59	return IRQ_HANDLED;
60}
61
62static int dir685_tk_probe(struct i2c_client *client)
63{
64	static const u8 bl_data[] = { 0xa7, 0x40 };
65	struct device *dev = &client->dev;
66	struct dir685_touchkeys *tk;
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	= "dlink-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