Input: add PCF8574 I2C keypad input device driver

Signed-off-by: Bryan Wu <cooloney@kernel.org>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

drivers/input/misc/Kconfig

@@ -277,6 +277,16 @@ config INPUT_PCF50633_PMU
 	 Say Y to include support for delivering  PMU events via  input
 	 layer on NXP PCF50633.
 
+config INPUT_PCF8574
+	tristate "PCF8574 Keypad input device"
+	depends on I2C && EXPERIMENTAL
+	help
+	  Say Y here if you want to support a keypad connetced via I2C
+	  with a PCF8574.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called pcf8574_keypad.
+
 config INPUT_GPIO_ROTARY_ENCODER
 	tristate "Rotary encoders connected to GPIO pins"
 	depends on GPIOLIB && GENERIC_GPIO

drivers/input/misc/Makefile

@@ -19,6 +19,7 @@ obj-$(CONFIG_INPUT_KEYSPAN_REMOTE)	+= keyspan_remote.o
 obj-$(CONFIG_INPUT_M68K_BEEP)		+= m68kspkr.o
 obj-$(CONFIG_INPUT_PCAP)		+= pcap_keys.o
 obj-$(CONFIG_INPUT_PCF50633_PMU)	+= pcf50633-input.o
+obj-$(CONFIG_INPUT_PCF8574)		+= pcf8574_keypad.o
 obj-$(CONFIG_INPUT_PCSPKR)		+= pcspkr.o
 obj-$(CONFIG_INPUT_POWERMATE)		+= powermate.o
 obj-$(CONFIG_INPUT_RB532_BUTTON)	+= rb532_button.o

drivers/input/misc/pcf8574_keypad.c

+/*
+ * 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 __devinit 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;
+
+	input_set_drvdata(idev, lp);
+
+	ret = input_register_device(idev);
+	if (ret) {
+		dev_err(&client->dev, "input_register_device() failed\n");
+		goto fail_register;
+	}
+
+	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_irq;
+	}
+
+	i2c_set_clientdata(client, lp);
+	return 0;
+
+ fail_irq:
+	input_unregister_device(idev);
+ fail_register:
+	input_set_drvdata(idev, NULL);
+	input_free_device(idev);
+ fail_allocate:
+	kfree(lp);
+
+	return ret;
+}
+
+static int __devexit 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);
+
+	i2c_set_clientdata(client, NULL);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM
+static int pcf8574_kp_resume(struct i2c_client *client)
+{
+	enable_irq(client->irq);
+
+	return 0;
+}
+
+static int pcf8574_kp_suspend(struct i2c_client *client, pm_message_t mesg)
+{
+	disable_irq(client->irq);
+
+	return 0;
+}
+#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,
+	},
+	.probe    = pcf8574_kp_probe,
+	.remove   = __devexit_p(pcf8574_kp_remove),
+	.suspend  = pcf8574_kp_suspend,
+	.resume   = pcf8574_kp_resume,
+	.id_table = pcf8574_kp_id,
+};
+
+static int __init pcf8574_kp_init(void)
+{
+	return i2c_add_driver(&pcf8574_kp_driver);
+}
+module_init(pcf8574_kp_init);
+
+static void __exit pcf8574_kp_exit(void)
+{
+	i2c_del_driver(&pcf8574_kp_driver);
+}
+module_exit(pcf8574_kp_exit);
+
+MODULE_AUTHOR("Michael Hennerich");
+MODULE_DESCRIPTION("Keypad input driver for 16 keys connected to PCF8574");
+MODULE_LICENSE("GPL");