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 
19 struct 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 
27 static 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 
62 static 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 
129 static const struct i2c_device_id dir685_tk_id[] = {
130 	{ "dir685tk", 0 },
131 	{ }
132 };
133 MODULE_DEVICE_TABLE(i2c, dir685_tk_id);
134 
135 #ifdef CONFIG_OF
136 static const struct of_device_id dir685_tk_of_match[] = {
137 	{ .compatible = "dlink,dir685-touchkeys" },
138 	{},
139 };
140 MODULE_DEVICE_TABLE(of, dir685_tk_of_match);
141 #endif
142 
143 static 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_new	= dir685_tk_probe,
149 	.id_table	= dir685_tk_id,
150 };
151 module_i2c_driver(dir685_tk_i2c_driver);
152 
153 MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>");
154 MODULE_DESCRIPTION("D-Link DIR-685 touchkeys driver");
155 MODULE_LICENSE("GPL");
156