1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * Driver for a keypad w/16 buttons connected to a PCF8574 I2C I/O expander
5 * Copyright 2005-2008 Analog Devices Inc.
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>
15 #define DRV_NAME "pcf8574_keypad"
17 static const unsigned char pcf8574_kp_btncode[] = {
38 unsigned short btncode[ARRAY_SIZE(pcf8574_kp_btncode)];
39 struct input_dev *idev;
40 struct i2c_client *client;
43 unsigned char laststate;
46 static short read_state(struct kp_data *lp)
48 unsigned char x, y, a, b;
50 i2c_smbus_write_byte(lp->client, 240);
51 x = 0xF & (~(i2c_smbus_read_byte(lp->client) >> 4));
53 i2c_smbus_write_byte(lp->client, 15);
54 y = 0xF & (~i2c_smbus_read_byte(lp->client));
56 for (a = 0; x > 0; a++)
58 for (b = 0; y > 0; b++)
61 return ((a - 1) * 4) + b;
64 static irqreturn_t pcf8574_kp_irq_handler(int irq, void *dev_id)
66 struct kp_data *lp = dev_id;
67 unsigned char nextstate = read_state(lp);
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];
74 input_report_key(lp->idev, keycode, key_down);
77 lp->laststate = nextstate;
83 static int pcf8574_kp_probe(struct i2c_client *client, const struct i2c_device_id *id)
86 struct input_dev *idev;
89 if (i2c_smbus_write_byte(client, 240) < 0) {
90 dev_err(&client->dev, "probe: write fail\n");
94 lp = kzalloc(sizeof(*lp), GFP_KERNEL);
98 idev = input_allocate_device();
100 dev_err(&client->dev, "Can't allocate input device\n");
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);
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);
119 __clear_bit(KEY_RESERVED, idev->keybit);
121 sprintf(lp->name, DRV_NAME);
122 sprintf(lp->phys, "kp_data/input0");
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;
131 lp->laststate = read_state(lp);
133 ret = request_threaded_irq(client->irq, NULL, pcf8574_kp_irq_handler,
134 IRQF_TRIGGER_LOW | IRQF_ONESHOT,
137 dev_err(&client->dev, "IRQ %d is not free\n", client->irq);
138 goto fail_free_device;
141 ret = input_register_device(idev);
143 dev_err(&client->dev, "input_register_device() failed\n");
147 i2c_set_clientdata(client, lp);
151 free_irq(client->irq, lp);
153 input_free_device(idev);
160 static void pcf8574_kp_remove(struct i2c_client *client)
162 struct kp_data *lp = i2c_get_clientdata(client);
164 free_irq(client->irq, lp);
166 input_unregister_device(lp->idev);
171 static int pcf8574_kp_resume(struct device *dev)
173 struct i2c_client *client = to_i2c_client(dev);
175 enable_irq(client->irq);
180 static int pcf8574_kp_suspend(struct device *dev)
182 struct i2c_client *client = to_i2c_client(dev);
184 disable_irq(client->irq);
189 static const struct dev_pm_ops pcf8574_kp_pm_ops = {
190 .suspend = pcf8574_kp_suspend,
191 .resume = pcf8574_kp_resume,
195 # define pcf8574_kp_resume NULL
196 # define pcf8574_kp_suspend NULL
199 static const struct i2c_device_id pcf8574_kp_id[] = {
203 MODULE_DEVICE_TABLE(i2c, pcf8574_kp_id);
205 static struct i2c_driver pcf8574_kp_driver = {
209 .pm = &pcf8574_kp_pm_ops,
212 .probe = pcf8574_kp_probe,
213 .remove = pcf8574_kp_remove,
214 .id_table = pcf8574_kp_id,
217 module_i2c_driver(pcf8574_kp_driver);
219 MODULE_AUTHOR("Michael Hennerich");
220 MODULE_DESCRIPTION("Keypad input driver for 16 keys connected to PCF8574");
221 MODULE_LICENSE("GPL");