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(client: lp->client, value: 240); |
51 | x = 0xF & (~(i2c_smbus_read_byte(client: lp->client) >> 4)); |
52 | |
53 | i2c_smbus_write_byte(client: lp->client, value: 15); |
54 | y = 0xF & (~i2c_smbus_read_byte(client: 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(dev: lp->idev, code: keycode, value: key_down); |
75 | input_sync(dev: 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, value: 240) < 0) { |
90 | dev_err(&client->dev, "probe: write fail\n" ); |
91 | return -ENODEV; |
92 | } |
93 | |
94 | lp = kzalloc(size: 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(buf: lp->name, DRV_NAME); |
122 | sprintf(buf: lp->phys, fmt: "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(irq: client->irq, NULL, thread_fn: pcf8574_kp_irq_handler, |
134 | IRQF_TRIGGER_LOW | IRQF_ONESHOT, |
135 | DRV_NAME, dev: 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, data: lp); |
148 | return 0; |
149 | |
150 | fail_free_irq: |
151 | free_irq(client->irq, lp); |
152 | fail_free_device: |
153 | input_free_device(dev: idev); |
154 | fail_allocate: |
155 | kfree(objp: 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(objp: 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(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(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 | |