1/*
2 * Driver for a keypad w/16 buttons connected to a PCF8574 I2C I/O expander
3 *
4 * Copyright 2005-2008 Analog Devices Inc.
5 *
6 * Licensed under the GPL-2 or later.
7 */
8
9#include <linux/module.h>
10#include <linux/input.h>
11#include <linux/interrupt.h>
12#include <linux/i2c.h>
13#include <linux/slab.h>
14#include <linux/workqueue.h>
15
16#define DRV_NAME "pcf8574_keypad"
17
18static const unsigned char pcf8574_kp_btncode[] = {
19 [0] = KEY_RESERVED,
20 [1] = KEY_ENTER,
21 [2] = KEY_BACKSLASH,
22 [3] = KEY_0,
23 [4] = KEY_RIGHTBRACE,
24 [5] = KEY_C,
25 [6] = KEY_9,
26 [7] = KEY_8,
27 [8] = KEY_7,
28 [9] = KEY_B,
29 [10] = KEY_6,
30 [11] = KEY_5,
31 [12] = KEY_4,
32 [13] = KEY_A,
33 [14] = KEY_3,
34 [15] = KEY_2,
35 [16] = KEY_1
36};
37
38struct kp_data {
39 unsigned short btncode[ARRAY_SIZE(pcf8574_kp_btncode)];
40 struct input_dev *idev;
41 struct i2c_client *client;
42 char name[64];
43 char phys[32];
44 unsigned char laststate;
45};
46
47static short read_state(struct kp_data *lp)
48{
49 unsigned char x, y, a, b;
50
51 i2c_smbus_write_byte(lp->client, 240);
52 x = 0xF & (~(i2c_smbus_read_byte(lp->client) >> 4));
53
54 i2c_smbus_write_byte(lp->client, 15);
55 y = 0xF & (~i2c_smbus_read_byte(lp->client));
56
57 for (a = 0; x > 0; a++)
58 x = x >> 1;
59 for (b = 0; y > 0; b++)
60 y = y >> 1;
61
62 return ((a - 1) * 4) + b;
63}
64
65static irqreturn_t pcf8574_kp_irq_handler(int irq, void *dev_id)
66{
67 struct kp_data *lp = dev_id;
68 unsigned char nextstate = read_state(lp);
69
70 if (lp->laststate != nextstate) {
71 int key_down = nextstate < ARRAY_SIZE(lp->btncode);
72 unsigned short keycode = key_down ?
73 lp->btncode[nextstate] : lp->btncode[lp->laststate];
74
75 input_report_key(lp->idev, keycode, key_down);
76 input_sync(lp->idev);
77
78 lp->laststate = nextstate;
79 }
80
81 return IRQ_HANDLED;
82}
83
84static int pcf8574_kp_probe(struct i2c_client *client, const struct i2c_device_id *id)
85{
86 int i, ret;
87 struct input_dev *idev;
88 struct kp_data *lp;
89
90 if (i2c_smbus_write_byte(client, 240) < 0) {
91 dev_err(&client->dev, "probe: write fail\n");
92 return -ENODEV;
93 }
94
95 lp = kzalloc(sizeof(*lp), GFP_KERNEL);
96 if (!lp)
97 return -ENOMEM;
98
99 idev = input_allocate_device();
100 if (!idev) {
101 dev_err(&client->dev, "Can't allocate input device\n");
102 ret = -ENOMEM;
103 goto fail_allocate;
104 }
105
106 lp->idev = idev;
107 lp->client = client;
108
109 idev->evbit[0] = BIT_MASK(EV_KEY);
110 idev->keycode = lp->btncode;
111 idev->keycodesize = sizeof(lp->btncode[0]);
112 idev->keycodemax = ARRAY_SIZE(lp->btncode);
113
114 for (i = 0; i < ARRAY_SIZE(pcf8574_kp_btncode); i++) {
115 if (lp->btncode[i] <= KEY_MAX) {
116 lp->btncode[i] = pcf8574_kp_btncode[i];
117 __set_bit(lp->btncode[i], idev->keybit);
118 }
119 }
120 __clear_bit(KEY_RESERVED, idev->keybit);
121
122 sprintf(lp->name, DRV_NAME);
123 sprintf(lp->phys, "kp_data/input0");
124
125 idev->name = lp->name;
126 idev->phys = lp->phys;
127 idev->id.bustype = BUS_I2C;
128 idev->id.vendor = 0x0001;
129 idev->id.product = 0x0001;
130 idev->id.version = 0x0100;
131
132 lp->laststate = read_state(lp);
133
134 ret = request_threaded_irq(client->irq, NULL, pcf8574_kp_irq_handler,
135 IRQF_TRIGGER_LOW | IRQF_ONESHOT,
136 DRV_NAME, lp);
137 if (ret) {
138 dev_err(&client->dev, "IRQ %d is not free\n", client->irq);
139 goto fail_free_device;
140 }
141
142 ret = input_register_device(idev);
143 if (ret) {
144 dev_err(&client->dev, "input_register_device() failed\n");
145 goto fail_free_irq;
146 }
147
148 i2c_set_clientdata(client, lp);
149 return 0;
150
151 fail_free_irq:
152 free_irq(client->irq, lp);
153 fail_free_device:
154 input_free_device(idev);
155 fail_allocate:
156 kfree(lp);
157
158 return ret;
159}
160
161static int pcf8574_kp_remove(struct i2c_client *client)
162{
163 struct kp_data *lp = i2c_get_clientdata(client);
164
165 free_irq(client->irq, lp);
166
167 input_unregister_device(lp->idev);
168 kfree(lp);
169
170 return 0;
171}
172
173#ifdef CONFIG_PM
174static int pcf8574_kp_resume(struct device *dev)
175{
176 struct i2c_client *client = to_i2c_client(dev);
177
178 enable_irq(client->irq);
179
180 return 0;
181}
182
183static int pcf8574_kp_suspend(struct device *dev)
184{
185 struct i2c_client *client = to_i2c_client(dev);
186
187 disable_irq(client->irq);
188
189 return 0;
190}
191
192static const struct dev_pm_ops pcf8574_kp_pm_ops = {
193 .suspend = pcf8574_kp_suspend,
194 .resume = pcf8574_kp_resume,
195};
196
197#else
198# define pcf8574_kp_resume NULL
199# define pcf8574_kp_suspend NULL
200#endif
201
202static const struct i2c_device_id pcf8574_kp_id[] = {
203 { DRV_NAME, 0 },
204 { }
205};
206MODULE_DEVICE_TABLE(i2c, pcf8574_kp_id);
207
208static struct i2c_driver pcf8574_kp_driver = {
209 .driver = {
210 .name = DRV_NAME,
211#ifdef CONFIG_PM
212 .pm = &pcf8574_kp_pm_ops,
213#endif
214 },
215 .probe = pcf8574_kp_probe,
216 .remove = pcf8574_kp_remove,
217 .id_table = pcf8574_kp_id,
218};
219
220module_i2c_driver(pcf8574_kp_driver);
221
222MODULE_AUTHOR("Michael Hennerich");
223MODULE_DESCRIPTION("Keypad input driver for 16 keys connected to PCF8574");
224MODULE_LICENSE("GPL");
225