Input: add keypad driver for keys interfaced to TCA6416

This patch implements a simple Keypad driver that functions
as an I2C client. It handles key press events for keys
connected to TCA6416 I2C based IO expander.

Signed-off-by: Sriramakrishnan <[e-mail]>
Signed-off-by: Dmitry Torokhov <[e-mail]>

drivers/input/keyboard/Kconfig

···
 	  To compile this driver as a module, choose M here: the
 	  module will be called gpio_keys.
 
+config KEYBOARD_TCA6416
+	tristate "TCA6416 Keypad Support"
+	depends on I2C
+	help
+	  This driver implements basic keypad functionality
+	  for keys connected through TCA6416 IO expander
+
+	  Say Y here if your device has keys connected to
+	  TCA6416 IO expander. Your board-specific setup logic
+	  must also provide pin-mask details(of which TCA6416 pins
+	  are used for keypad).
+
+	  If enabled the complete TCA6416 device will be managed through
+	  this driver.
+
+
 config KEYBOARD_MATRIX
 	tristate "GPIO driven matrix keypad support"
 	depends on GENERIC_GPIO

drivers/input/keyboard/Makefile

···
 obj-$(CONFIG_KEYBOARD_DAVINCI)		+= davinci_keyscan.o
 obj-$(CONFIG_KEYBOARD_EP93XX)		+= ep93xx_keypad.o
 obj-$(CONFIG_KEYBOARD_GPIO)		+= gpio_keys.o
+obj-$(CONFIG_KEYBOARD_TCA6416)		+= tca6416-keypad.o
 obj-$(CONFIG_KEYBOARD_HIL)		+= hil_kbd.o
 obj-$(CONFIG_KEYBOARD_HIL_OLD)		+= hilkbd.o
 obj-$(CONFIG_KEYBOARD_IMX)		+= imx_keypad.o

drivers/input/keyboard/tca6416-keypad.c

···
+/*
+ * Driver for keys on TCA6416 I2C IO expander
+ *
+ * Copyright (C) 2010 Texas Instruments
+ *
+ * Author : Sriramakrishnan.A.G. <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/types.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/slab.h>
+#include <linux/interrupt.h>
+#include <linux/workqueue.h>
+#include <linux/gpio.h>
+#include <linux/i2c.h>
+#include <linux/input.h>
+#include <linux/tca6416_keypad.h>
+
+#define TCA6416_INPUT          0
+#define TCA6416_OUTPUT         1
+#define TCA6416_INVERT         2
+#define TCA6416_DIRECTION      3
+
+static const struct i2c_device_id tca6416_id[] = {
+	{ "tca6416-keys", 16, },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, tca6416_id);
+
+struct tca6416_drv_data {
+	struct input_dev *input;
+	struct tca6416_button data[0];
+};
+
+struct tca6416_keypad_chip {
+	uint16_t reg_output;
+	uint16_t reg_direction;
+	uint16_t reg_input;
+
+	struct i2c_client *client;
+	struct input_dev *input;
+	struct delayed_work dwork;
+	u16 pinmask;
+	int irqnum;
+	bool use_polling;
+	struct tca6416_button buttons[0];
+};
+
+static int tca6416_write_reg(struct tca6416_keypad_chip *chip, int reg, u16 val)
+{
+	int error;
+
+	error = i2c_smbus_write_word_data(chip->client, reg << 1, val);
+	if (error < 0) {
+		dev_err(&chip->client->dev,
+			"%s failed, reg: %d, val: %d, error: %d\n",
+			__func__, reg, val, error);
+		return error;
+	}
+
+	return 0;
+}
+
+static int tca6416_read_reg(struct tca6416_keypad_chip *chip, int reg, u16 *val)
+{
+	int retval;
+
+	retval = i2c_smbus_read_word_data(chip->client, reg << 1);
+	if (retval < 0) {
+		dev_err(&chip->client->dev, "%s failed, reg: %d, error: %d\n",
+			__func__, reg, retval);
+		return retval;
+	}
+
+	*val = (u16)retval;
+	return 0;
+}
+
+static void tca6416_keys_scan(struct tca6416_keypad_chip *chip)
+{
+	struct input_dev *input = chip->input;
+	u16 reg_val, val;
+	int error, i, pin_index;
+
+	error = tca6416_read_reg(chip, TCA6416_INPUT, &reg_val);
+	if (error)
+		return;
+
+	reg_val &= chip->pinmask;
+
+	/* Figure out which lines have changed */
+	val = reg_val ^ chip->reg_input;
+	chip->reg_input = reg_val;
+
+	for (i = 0, pin_index = 0; i < 16; i++) {
+		if (val & (1 << i)) {
+			struct tca6416_button *button = &chip->buttons[pin_index];
+			unsigned int type = button->type ?: EV_KEY;
+			int state = ((reg_val & (1 << i)) ? 1 : 0)
+						^ button->active_low;
+
+			input_event(input, type, button->code, !!state);
+			input_sync(input);
+		}
+
+		if (chip->pinmask & (1 << i))
+			pin_index++;
+	}
+}
+
+/*
+ * This is threaded IRQ handler and this can (and will) sleep.
+ */
+static irqreturn_t tca6416_keys_isr(int irq, void *dev_id)
+{
+	struct tca6416_keypad_chip *chip = dev_id;
+
+	tca6416_keys_scan(chip);
+
+	return IRQ_HANDLED;
+}
+
+static void tca6416_keys_work_func(struct work_struct *work)
+{
+	struct tca6416_keypad_chip *chip =
+		container_of(work, struct tca6416_keypad_chip, dwork.work);
+
+	tca6416_keys_scan(chip);
+	schedule_delayed_work(&chip->dwork, msecs_to_jiffies(100));
+}
+
+static int tca6416_keys_open(struct input_dev *dev)
+{
+	struct tca6416_keypad_chip *chip = input_get_drvdata(dev);
+
+	/* Get initial device state in case it has switches */
+	tca6416_keys_scan(chip);
+
+	if (chip->use_polling)
+		schedule_delayed_work(&chip->dwork, msecs_to_jiffies(100));
+	else
+		enable_irq(chip->irqnum);
+
+	return 0;
+}
+
+static void tca6416_keys_close(struct input_dev *dev)
+{
+	struct tca6416_keypad_chip *chip = input_get_drvdata(dev);
+
+	if (chip->use_polling)
+		cancel_delayed_work_sync(&chip->dwork);
+	else
+		disable_irq(chip->irqnum);
+}
+
+static int __devinit tca6416_setup_registers(struct tca6416_keypad_chip *chip)
+{
+	int error;
+
+	error = tca6416_read_reg(chip, TCA6416_OUTPUT, &chip->reg_output);
+	if (error)
+		return error;
+
+	error = tca6416_read_reg(chip, TCA6416_DIRECTION, &chip->reg_direction);
+	if (error)
+		return error;
+
+	/* ensure that keypad pins are set to input */
+	error = tca6416_write_reg(chip, TCA6416_DIRECTION,
+				  chip->reg_direction | chip->pinmask);
+	if (error)
+		return error;
+
+	error = tca6416_read_reg(chip, TCA6416_DIRECTION, &chip->reg_direction);
+	if (error)
+		return error;
+
+	error = tca6416_read_reg(chip, TCA6416_INPUT, &chip->reg_input);
+	if (error)
+		return error;
+
+	chip->reg_input &= chip->pinmask;
+
+	return 0;
+}
+
+static int __devinit tca6416_keypad_probe(struct i2c_client *client,
+				   const struct i2c_device_id *id)
+{
+	struct tca6416_keys_platform_data *pdata;
+	struct tca6416_keypad_chip *chip;
+	struct input_dev *input;
+	int error;
+	int i;
+
+	/* Check functionality */
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE)) {
+		dev_err(&client->dev, "%s adapter not supported\n",
+			dev_driver_string(&client->adapter->dev));
+		return -ENODEV;
+	}
+
+	pdata = client->dev.platform_data;
+	if (!pdata) {
+		dev_dbg(&client->dev, "no platform data\n");
+		return -EINVAL;
+	}
+
+	chip = kzalloc(sizeof(struct tca6416_keypad_chip) +
+		       pdata->nbuttons * sizeof(struct tca6416_button),
+		       GFP_KERNEL);
+	input = input_allocate_device();
+	if (!chip || !input) {
+		error = -ENOMEM;
+		goto fail1;
+	}
+
+	chip->client = client;
+	chip->input = input;
+	chip->pinmask = pdata->pinmask;
+	chip->use_polling = pdata->use_polling;
+
+	INIT_DELAYED_WORK(&chip->dwork, tca6416_keys_work_func);
+
+	input->phys = "tca6416-keys/input0";
+	input->name = client->name;
+	input->dev.parent = &client->dev;
+
+	input->open = tca6416_keys_open;
+	input->close = tca6416_keys_close;
+
+	input->id.bustype = BUS_HOST;
+	input->id.vendor = 0x0001;
+	input->id.product = 0x0001;
+	input->id.version = 0x0100;
+
+	/* Enable auto repeat feature of Linux input subsystem */
+	if (pdata->rep)
+		__set_bit(EV_REP, input->evbit);
+
+	for (i = 0; i < pdata->nbuttons; i++) {
+		unsigned int type;
+
+		chip->buttons[i] = pdata->buttons[i];
+		type = (pdata->buttons[i].type) ?: EV_KEY;
+		input_set_capability(input, type, pdata->buttons[i].code);
+	}
+
+	input_set_drvdata(input, chip);
+
+	/*
+	 * Initialize cached registers from their original values.
+	 * we can't share this chip with another i2c master.
+	 */
+	error = tca6416_setup_registers(chip);
+	if (error)
+		goto fail1;
+
+	if (!chip->use_polling) {
+		if (pdata->irq_is_gpio)
+			chip->irqnum = gpio_to_irq(client->irq);
+		else
+			chip->irqnum = client->irq;
+
+		error = request_threaded_irq(chip->irqnum, NULL,
+					     tca6416_keys_isr,
+					     IRQF_TRIGGER_FALLING,
+					     "tca6416-keypad", chip);
+		if (error) {
+			dev_dbg(&client->dev,
+				"Unable to claim irq %d; error %d\n",
+				chip->irqnum, error);
+			goto fail1;
+		}
+		disable_irq(chip->irqnum);
+	}
+
+	error = input_register_device(input);
+	if (error) {
+		dev_dbg(&client->dev,
+			"Unable to register input device, error: %d\n", error);
+		goto fail2;
+	}
+
+	i2c_set_clientdata(client, chip);
+
+	return 0;
+
+fail2:
+	if (!chip->use_polling) {
+		free_irq(chip->irqnum, chip);
+		enable_irq(chip->irqnum);
+	}
+fail1:
+	input_free_device(input);
+	kfree(chip);
+	return error;
+}
+
+static int __devexit tca6416_keypad_remove(struct i2c_client *client)
+{
+	struct tca6416_keypad_chip *chip = i2c_get_clientdata(client);
+
+	if (!chip->use_polling) {
+		free_irq(chip->irqnum, chip);
+		enable_irq(chip->irqnum);
+	}
+
+	input_unregister_device(chip->input);
+	kfree(chip);
+
+	i2c_set_clientdata(client, NULL);
+
+	return 0;
+}
+
+
+static struct i2c_driver tca6416_keypad_driver = {
+	.driver = {
+		.name	= "tca6416-keypad",
+	},
+	.probe		= tca6416_keypad_probe,
+	.remove		= __devexit_p(tca6416_keypad_remove),
+	.id_table	= tca6416_id,
+};
+
+static int __init tca6416_keypad_init(void)
+{
+	return i2c_add_driver(&tca6416_keypad_driver);
+}
+
+subsys_initcall(tca6416_keypad_init);
+
+static void __exit tca6416_keypad_exit(void)
+{
+	i2c_del_driver(&tca6416_keypad_driver);
+}
+module_exit(tca6416_keypad_exit);
+
+MODULE_AUTHOR("Sriramakrishnan <[e-mail]>");
+MODULE_DESCRIPTION("Keypad driver over tca6146 IO expander");
+MODULE_LICENSE("GPL");

include/linux/tca6416_keypad.h

···
+/*
+ * tca6416 keypad platform support
+ *
+ * Copyright (C) 2010 Texas Instruments
+ *
+ * Author: Sriramakrishnan <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef _TCA6416_KEYS_H
+#define _TCA6416_KEYS_H
+
+#include <linux/types.h>
+
+struct tca6416_button {
+	/* Configuration parameters */
+	int code;		/* input event code (KEY_*, SW_*) */
+	int active_low;
+	int type;		/* input event type (EV_KEY, EV_SW) */
+};
+
+struct tca6416_keys_platform_data {
+	struct tca6416_button *buttons;
+	int nbuttons;
+	unsigned int rep:1;	/* enable input subsystem auto repeat */
+	uint16_t pinmask;
+	uint16_t invert;
+	int irq_is_gpio;
+	int use_polling;	/* use polling if Interrupt is not connected*/
+};
+#endif