dlink-dir685-touchkeys.c

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