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 | |
18 | static 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 | |
38 | struct 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 | |
47 | static 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 | |
65 | static 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 | |
84 | static 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 | |
161 | static 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 |
174 | static 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 | |
183 | static 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 | |
192 | static 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 | |
202 | static const struct i2c_device_id pcf8574_kp_id[] = { |
203 | { DRV_NAME, 0 }, |
204 | { } |
205 | }; |
206 | MODULE_DEVICE_TABLE(i2c, pcf8574_kp_id); |
207 | |
208 | static 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 | |
220 | module_i2c_driver(pcf8574_kp_driver); |
221 | |
222 | MODULE_AUTHOR("Michael Hennerich" ); |
223 | MODULE_DESCRIPTION("Keypad input driver for 16 keys connected to PCF8574" ); |
224 | MODULE_LICENSE("GPL" ); |
225 | |