1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Driver for a keypad w/16 buttons connected to a PCF8574 I2C I/O expander
4  *
5  * Copyright 2005-2008 Analog Devices Inc.
6  */
7 
8 #include <linux/module.h>
9 #include <linux/input.h>
10 #include <linux/interrupt.h>
11 #include <linux/i2c.h>
12 #include <linux/slab.h>
13 #include <linux/workqueue.h>
14 
15 #define DRV_NAME "pcf8574_keypad"
16 
17 static const unsigned char pcf8574_kp_btncode[] = {
18 	[0] = KEY_RESERVED,
19 	[1] = KEY_ENTER,
20 	[2] = KEY_BACKSLASH,
21 	[3] = KEY_0,
22 	[4] = KEY_RIGHTBRACE,
23 	[5] = KEY_C,
24 	[6] = KEY_9,
25 	[7] = KEY_8,
26 	[8] = KEY_7,
27 	[9] = KEY_B,
28 	[10] = KEY_6,
29 	[11] = KEY_5,
30 	[12] = KEY_4,
31 	[13] = KEY_A,
32 	[14] = KEY_3,
33 	[15] = KEY_2,
34 	[16] = KEY_1
35 };
36 
37 struct kp_data {
38 	unsigned short btncode[ARRAY_SIZE(pcf8574_kp_btncode)];
39 	struct input_dev *idev;
40 	struct i2c_client *client;
41 	char name[64];
42 	char phys[32];
43 	unsigned char laststate;
44 };
45 
46 static short read_state(struct kp_data *lp)
47 {
48 	unsigned char x, y, a, b;
49 
50 	i2c_smbus_write_byte(lp->client, 240);
51 	x = 0xF & (~(i2c_smbus_read_byte(lp->client) >> 4));
52 
53 	i2c_smbus_write_byte(lp->client, 15);
54 	y = 0xF & (~i2c_smbus_read_byte(lp->client));
55 
56 	for (a = 0; x > 0; a++)
57 		x = x >> 1;
58 	for (b = 0; y > 0; b++)
59 		y = y >> 1;
60 
61 	return ((a - 1) * 4) + b;
62 }
63 
64 static irqreturn_t pcf8574_kp_irq_handler(int irq, void *dev_id)
65 {
66 	struct kp_data *lp = dev_id;
67 	unsigned char nextstate = read_state(lp);
68 
69 	if (lp->laststate != nextstate) {
70 		int key_down = nextstate < ARRAY_SIZE(lp->btncode);
71 		unsigned short keycode = key_down ?
72 			lp->btncode[nextstate] : lp->btncode[lp->laststate];
73 
74 		input_report_key(lp->idev, keycode, key_down);
75 		input_sync(lp->idev);
76 
77 		lp->laststate = nextstate;
78 	}
79 
80 	return IRQ_HANDLED;
81 }
82 
83 static int pcf8574_kp_probe(struct i2c_client *client)
84 {
85 	int i, ret;
86 	struct input_dev *idev;
87 	struct kp_data *lp;
88 
89 	if (i2c_smbus_write_byte(client, 240) < 0) {
90 		dev_err(&client->dev, "probe: write fail\n");
91 		return -ENODEV;
92 	}
93 
94 	lp = kzalloc(sizeof(*lp), GFP_KERNEL);
95 	if (!lp)
96 		return -ENOMEM;
97 
98 	idev = input_allocate_device();
99 	if (!idev) {
100 		dev_err(&client->dev, "Can't allocate input device\n");
101 		ret = -ENOMEM;
102 		goto fail_allocate;
103 	}
104 
105 	lp->idev = idev;
106 	lp->client = client;
107 
108 	idev->evbit[0] = BIT_MASK(EV_KEY);
109 	idev->keycode = lp->btncode;
110 	idev->keycodesize = sizeof(lp->btncode[0]);
111 	idev->keycodemax = ARRAY_SIZE(lp->btncode);
112 
113 	for (i = 0; i < ARRAY_SIZE(pcf8574_kp_btncode); i++) {
114 		if (lp->btncode[i] <= KEY_MAX) {
115 			lp->btncode[i] = pcf8574_kp_btncode[i];
116 			__set_bit(lp->btncode[i], idev->keybit);
117 		}
118 	}
119 	__clear_bit(KEY_RESERVED, idev->keybit);
120 
121 	sprintf(lp->name, DRV_NAME);
122 	sprintf(lp->phys, "kp_data/input0");
123 
124 	idev->name = lp->name;
125 	idev->phys = lp->phys;
126 	idev->id.bustype = BUS_I2C;
127 	idev->id.vendor = 0x0001;
128 	idev->id.product = 0x0001;
129 	idev->id.version = 0x0100;
130 
131 	lp->laststate = read_state(lp);
132 
133 	ret = request_threaded_irq(client->irq, NULL, pcf8574_kp_irq_handler,
134 				   IRQF_TRIGGER_LOW | IRQF_ONESHOT,
135 				   DRV_NAME, lp);
136 	if (ret) {
137 		dev_err(&client->dev, "IRQ %d is not free\n", client->irq);
138 		goto fail_free_device;
139 	}
140 
141 	ret = input_register_device(idev);
142 	if (ret) {
143 		dev_err(&client->dev, "input_register_device() failed\n");
144 		goto fail_free_irq;
145 	}
146 
147 	i2c_set_clientdata(client, lp);
148 	return 0;
149 
150  fail_free_irq:
151 	free_irq(client->irq, lp);
152  fail_free_device:
153 	input_free_device(idev);
154  fail_allocate:
155 	kfree(lp);
156 
157 	return ret;
158 }
159 
160 static void pcf8574_kp_remove(struct i2c_client *client)
161 {
162 	struct kp_data *lp = i2c_get_clientdata(client);
163 
164 	free_irq(client->irq, lp);
165 
166 	input_unregister_device(lp->idev);
167 	kfree(lp);
168 }
169 
170 static int pcf8574_kp_resume(struct device *dev)
171 {
172 	struct i2c_client *client = to_i2c_client(dev);
173 
174 	enable_irq(client->irq);
175 
176 	return 0;
177 }
178 
179 static int pcf8574_kp_suspend(struct device *dev)
180 {
181 	struct i2c_client *client = to_i2c_client(dev);
182 
183 	disable_irq(client->irq);
184 
185 	return 0;
186 }
187 
188 static DEFINE_SIMPLE_DEV_PM_OPS(pcf8574_kp_pm_ops,
189 				pcf8574_kp_suspend, pcf8574_kp_resume);
190 
191 static const struct i2c_device_id pcf8574_kp_id[] = {
192 	{ DRV_NAME, 0 },
193 	{ }
194 };
195 MODULE_DEVICE_TABLE(i2c, pcf8574_kp_id);
196 
197 static struct i2c_driver pcf8574_kp_driver = {
198 	.driver = {
199 		.name  = DRV_NAME,
200 		.pm = pm_sleep_ptr(&pcf8574_kp_pm_ops),
201 	},
202 	.probe    = pcf8574_kp_probe,
203 	.remove   = pcf8574_kp_remove,
204 	.id_table = pcf8574_kp_id,
205 };
206 
207 module_i2c_driver(pcf8574_kp_driver);
208 
209 MODULE_AUTHOR("Michael Hennerich");
210 MODULE_DESCRIPTION("Keypad input driver for 16 keys connected to PCF8574");
211 MODULE_LICENSE("GPL");
212