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/*
* Driver for a keypad w/16 buttons connected to a PCF8574 I2C I/O expander
*
* Copyright 2005-2008 Analog Devices Inc.
*
* Licensed under the GPL-2 or later.
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/input.h>
#include <linux/interrupt.h>
#include <linux/i2c.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
#define DRV_NAME "pcf8574_keypad"
static const unsigned char pcf8574_kp_btncode[] = {
[0] = KEY_RESERVED,
[1] = KEY_ENTER,
[2] = KEY_BACKSLASH,
[3] = KEY_0,
[4] = KEY_RIGHTBRACE,
[5] = KEY_C,
[6] = KEY_9,
[7] = KEY_8,
[8] = KEY_7,
[9] = KEY_B,
[10] = KEY_6,
[11] = KEY_5,
[12] = KEY_4,
[13] = KEY_A,
[14] = KEY_3,
[15] = KEY_2,
[16] = KEY_1
};
struct kp_data {
unsigned short btncode[ARRAY_SIZE(pcf8574_kp_btncode)];
struct input_dev *idev;
struct i2c_client *client;
char name[64];
char phys[32];
unsigned char laststate;
};
static short read_state(struct kp_data *lp)
{
unsigned char x, y, a, b;
i2c_smbus_write_byte(lp->client, 240);
x = 0xF & (~(i2c_smbus_read_byte(lp->client) >> 4));
i2c_smbus_write_byte(lp->client, 15);
y = 0xF & (~i2c_smbus_read_byte(lp->client));
for (a = 0; x > 0; a++)
x = x >> 1;
for (b = 0; y > 0; b++)
y = y >> 1;
return ((a - 1) * 4) + b;
}
static irqreturn_t pcf8574_kp_irq_handler(int irq, void *dev_id)
{
struct kp_data *lp = dev_id;
unsigned char nextstate = read_state(lp);
if (lp->laststate != nextstate) {
int key_down = nextstate < ARRAY_SIZE(lp->btncode);
unsigned short keycode = key_down ?
lp->btncode[nextstate] : lp->btncode[lp->laststate];
input_report_key(lp->idev, keycode, key_down);
input_sync(lp->idev);
lp->laststate = nextstate;
}
return IRQ_HANDLED;
}
static int pcf8574_kp_probe(struct i2c_client *client, const struct i2c_device_id *id)
{
int i, ret;
struct input_dev *idev;
struct kp_data *lp;
if (i2c_smbus_write_byte(client, 240) < 0) {
dev_err(&client->dev, "probe: write fail\n");
return -ENODEV;
}
lp = kzalloc(sizeof(*lp), GFP_KERNEL);
if (!lp)
return -ENOMEM;
idev = input_allocate_device();
if (!idev) {
dev_err(&client->dev, "Can't allocate input device\n");
ret = -ENOMEM;
goto fail_allocate;
}
lp->idev = idev;
lp->client = client;
idev->evbit[0] = BIT_MASK(EV_KEY);
idev->keycode = lp->btncode;
idev->keycodesize = sizeof(lp->btncode[0]);
idev->keycodemax = ARRAY_SIZE(lp->btncode);
for (i = 0; i < ARRAY_SIZE(pcf8574_kp_btncode); i++) {
lp->btncode[i] = pcf8574_kp_btncode[i];
__set_bit(lp->btncode[i] & KEY_MAX, idev->keybit);
}
sprintf(lp->name, DRV_NAME);
sprintf(lp->phys, "kp_data/input0");
idev->name = lp->name;
idev->phys = lp->phys;
idev->id.bustype = BUS_I2C;
idev->id.vendor = 0x0001;
idev->id.product = 0x0001;
idev->id.version = 0x0100;
lp->laststate = read_state(lp);
ret = request_threaded_irq(client->irq, NULL, pcf8574_kp_irq_handler,
IRQF_TRIGGER_LOW | IRQF_ONESHOT,
DRV_NAME, lp);
if (ret) {
dev_err(&client->dev, "IRQ %d is not free\n", client->irq);
goto fail_free_device;
}
ret = input_register_device(idev);
if (ret) {
dev_err(&client->dev, "input_register_device() failed\n");
goto fail_free_irq;
}
i2c_set_clientdata(client, lp);
return 0;
fail_free_irq:
free_irq(client->irq, lp);
fail_free_device:
input_free_device(idev);
fail_allocate:
kfree(lp);
return ret;
}
static int pcf8574_kp_remove(struct i2c_client *client)
{
struct kp_data *lp = i2c_get_clientdata(client);
free_irq(client->irq, lp);
input_unregister_device(lp->idev);
kfree(lp);
return 0;
}
#ifdef CONFIG_PM
static int pcf8574_kp_resume(struct device *dev)
{
struct i2c_client *client = to_i2c_client(dev);
enable_irq(client->irq);
return 0;
}
static int pcf8574_kp_suspend(struct device *dev)
{
struct i2c_client *client = to_i2c_client(dev);
disable_irq(client->irq);
return 0;
}
static const struct dev_pm_ops pcf8574_kp_pm_ops = {
.suspend = pcf8574_kp_suspend,
.resume = pcf8574_kp_resume,
};
#else
# define pcf8574_kp_resume NULL
# define pcf8574_kp_suspend NULL
#endif
static const struct i2c_device_id pcf8574_kp_id[] = {
{ DRV_NAME, 0 },
{ }
};
MODULE_DEVICE_TABLE(i2c, pcf8574_kp_id);
static struct i2c_driver pcf8574_kp_driver = {
.driver = {
.name = DRV_NAME,
.owner = THIS_MODULE,
#ifdef CONFIG_PM
.pm = &pcf8574_kp_pm_ops,
#endif
},
.probe = pcf8574_kp_probe,
.remove = pcf8574_kp_remove,
.id_table = pcf8574_kp_id,
};
module_i2c_driver(pcf8574_kp_driver);
MODULE_AUTHOR("Michael Hennerich");
MODULE_DESCRIPTION("Keypad input driver for 16 keys connected to PCF8574");
MODULE_LICENSE("GPL");
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