drivers/input/misc/atmel_captouch.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Atmel Atmegaxx Capacitive Touch Button Driver
  *
  * Copyright (C) 2016 Google, inc.
  */

 /*
  * It's irrelevant that the HW used to develop captouch driver is based
  * on Atmega88PA part and uses QtouchADC parts for sensing touch.
  * Calling this driver "captouch" is an arbitrary way to distinguish
  * the protocol this driver supported by other atmel/qtouch drivers.
  *
  * Captouch driver supports a newer/different version of the I2C
  * registers/commands than the qt1070.c driver.
  * Don't let the similarity of the general driver structure fool you.
  *
  * For raw i2c access from userspace, use i2cset/i2cget
  * to poke at /dev/i2c-N devices.
  */

 #include <linux/device.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/i2c.h>
 #include <linux/input.h>
 #include <linux/interrupt.h>
 #include <linux/slab.h>

 /* Maximum number of buttons supported */
 #define MAX_NUM_OF_BUTTONS		8

 /* Registers */
 #define REG_KEY1_THRESHOLD		0x02
 #define REG_KEY2_THRESHOLD		0x03
 #define REG_KEY3_THRESHOLD		0x04
 #define REG_KEY4_THRESHOLD		0x05

 #define REG_KEY1_REF_H			0x20
 #define REG_KEY1_REF_L			0x21
 #define REG_KEY2_REF_H			0x22
 #define REG_KEY2_REF_L			0x23
 #define REG_KEY3_REF_H			0x24
 #define REG_KEY3_REF_L			0x25
 #define REG_KEY4_REF_H			0x26
 #define REG_KEY4_REF_L			0x27

 #define REG_KEY1_DLT_H			0x30
 #define REG_KEY1_DLT_L			0x31
 #define REG_KEY2_DLT_H			0x32
 #define REG_KEY2_DLT_L			0x33
 #define REG_KEY3_DLT_H			0x34
 #define REG_KEY3_DLT_L			0x35
 #define REG_KEY4_DLT_H			0x36
 #define REG_KEY4_DLT_L			0x37

 #define REG_KEY_STATE			0x3C

 /*
  * @i2c_client: I2C slave device client pointer
  * @input: Input device pointer
  * @num_btn: Number of buttons
  * @keycodes: map of button# to KeyCode
  * @prev_btn: Previous key state to detect button "press" or "release"
  * @xfer_buf: I2C transfer buffer
  */
 struct atmel_captouch_device {
 	struct i2c_client *client;
 	struct input_dev *input;
 	u32 num_btn;
 	u32 keycodes[MAX_NUM_OF_BUTTONS];
 	u8 prev_btn;
 	u8 xfer_buf[8] ____cacheline_aligned;
 };

 /*
  * Read from I2C slave device
  * The protocol is that the client has to provide both the register address
  * and the length, and while reading back the device would prepend the data
  * with address and length for verification.
  */
 static int atmel_read(struct atmel_captouch_device *capdev,
 			 u8 reg, u8 *data, size_t len)
 {
 	struct i2c_client *client = capdev->client;
 	struct device *dev = &client->dev;
 	struct i2c_msg msg[2];
 	int err;

 	if (len > sizeof(capdev->xfer_buf) - 2)
 		return -EINVAL;

 	capdev->xfer_buf[0] = reg;
 	capdev->xfer_buf[1] = len;

 	msg[0].addr = client->addr;
 	msg[0].flags = 0;
 	msg[0].buf = capdev->xfer_buf;
 	msg[0].len = 2;

 	msg[1].addr = client->addr;
 	msg[1].flags = I2C_M_RD;
 	msg[1].buf = capdev->xfer_buf;
 	msg[1].len = len + 2;

 	err = i2c_transfer(client->adapter, msg, ARRAY_SIZE(msg));
 	if (err != ARRAY_SIZE(msg))
 		return err < 0 ? err : -EIO;

 	if (capdev->xfer_buf[0] != reg) {
 		dev_err(dev,
 			"I2C read error: register address does not match (%#02x vs %02x)\n",
 			capdev->xfer_buf[0], reg);
 		return -ECOMM;
 	}

 	memcpy(data, &capdev->xfer_buf[2], len);

 	return 0;
 }

 /*
  * Handle interrupt and report the key changes to the input system.
  * Multi-touch can be supported; however, it really depends on whether
  * the device can multi-touch.
  */
 static irqreturn_t atmel_captouch_isr(int irq, void *data)
 {
 	struct atmel_captouch_device *capdev = data;
 	struct device *dev = &capdev->client->dev;
 	int error;
 	int i;
 	u8 new_btn;
 	u8 changed_btn;

 	error = atmel_read(capdev, REG_KEY_STATE, &new_btn, 1);
 	if (error) {
 		dev_err(dev, "failed to read button state: %d\n", error);
 		goto out;
 	}

 	dev_dbg(dev, "%s: button state %#02x\n", __func__, new_btn);

 	changed_btn = new_btn ^ capdev->prev_btn;
 	capdev->prev_btn = new_btn;

 	for (i = 0; i < capdev->num_btn; i++) {
 		if (changed_btn & BIT(i))
 			input_report_key(capdev->input,
 					 capdev->keycodes[i],
 					 new_btn & BIT(i));
 	}

 	input_sync(capdev->input);

 out:
 	return IRQ_HANDLED;
 }

 /*
  * Probe function to setup the device, input system and interrupt
  */
 static int atmel_captouch_probe(struct i2c_client *client)
 {
 	struct atmel_captouch_device *capdev;
 	struct device *dev = &client->dev;
 	struct device_node *node;
 	int i;
 	int err;

 	if (!i2c_check_functionality(client->adapter,
 				     I2C_FUNC_SMBUS_BYTE_DATA |
 					I2C_FUNC_SMBUS_WORD_DATA |
 					I2C_FUNC_SMBUS_I2C_BLOCK)) {
 		dev_err(dev, "needed i2c functionality is not supported\n");
 		return -EINVAL;
 	}

 	capdev = devm_kzalloc(dev, sizeof(*capdev), GFP_KERNEL);
 	if (!capdev)
 		return -ENOMEM;

 	capdev->client = client;

 	err = atmel_read(capdev, REG_KEY_STATE,
 			    &capdev->prev_btn, sizeof(capdev->prev_btn));
 	if (err) {
 		dev_err(dev, "failed to read initial button state: %d\n", err);
 		return err;
 	}

 	capdev->input = devm_input_allocate_device(dev);
 	if (!capdev->input) {
 		dev_err(dev, "failed to allocate input device\n");
 		return -ENOMEM;
 	}

 	capdev->input->id.bustype = BUS_I2C;
 	capdev->input->id.product = 0x880A;
 	capdev->input->id.version = 0;
 	capdev->input->name = "ATMegaXX Capacitive Button Controller";
 	__set_bit(EV_KEY, capdev->input->evbit);

 	node = dev->of_node;
 	if (!node) {
 		dev_err(dev, "failed to find matching node in device tree\n");
 		return -EINVAL;
 	}

 	if (of_property_read_bool(node, "autorepeat"))
 		__set_bit(EV_REP, capdev->input->evbit);

 	capdev->num_btn = of_property_count_u32_elems(node, "linux,keymap");
 	if (capdev->num_btn > MAX_NUM_OF_BUTTONS)
 		capdev->num_btn = MAX_NUM_OF_BUTTONS;

 	err = of_property_read_u32_array(node, "linux,keycodes",
 					 capdev->keycodes,
 					 capdev->num_btn);
 	if (err) {
 		dev_err(dev,
 			"failed to read linux,keycode property: %d\n", err);
 		return err;
 	}

 	for (i = 0; i < capdev->num_btn; i++)
 		__set_bit(capdev->keycodes[i], capdev->input->keybit);

 	capdev->input->keycode = capdev->keycodes;
 	capdev->input->keycodesize = sizeof(capdev->keycodes[0]);
 	capdev->input->keycodemax = capdev->num_btn;

 	err = input_register_device(capdev->input);
 	if (err)
 		return err;

 	err = devm_request_threaded_irq(dev, client->irq,
 					NULL, atmel_captouch_isr,
 					IRQF_ONESHOT,
 					"atmel_captouch", capdev);
 	if (err) {
 		dev_err(dev, "failed to request irq %d: %d\n",
 			client->irq, err);
 		return err;
 	}

 	return 0;
 }

 static const struct of_device_id atmel_captouch_of_id[] = {
 	{
 		.compatible = "atmel,captouch",
 	},
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, atmel_captouch_of_id);

 static const struct i2c_device_id atmel_captouch_id[] = {
 	{ "atmel_captouch" },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, atmel_captouch_id);

 static struct i2c_driver atmel_captouch_driver = {
 	.probe		= atmel_captouch_probe,
 	.id_table	= atmel_captouch_id,
 	.driver		= {
 		.name	= "atmel_captouch",
 		.of_match_table = atmel_captouch_of_id,
 	},
 };
 module_i2c_driver(atmel_captouch_driver);

 /* Module information */
 MODULE_AUTHOR("Hung-yu Wu <hywu@google.com>");
 MODULE_DESCRIPTION("Atmel ATmegaXX Capacitance Touch Sensor I2C Driver");
 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Atmel Atmegaxx Capacitive Touch Button Driver
	*
	* Copyright (C) 2016 Google, inc.
	*/

	/*
	* It's irrelevant that the HW used to develop captouch driver is based
	* on Atmega88PA part and uses QtouchADC parts for sensing touch.
	* Calling this driver "captouch" is an arbitrary way to distinguish
	* the protocol this driver supported by other atmel/qtouch drivers.
	*
	* Captouch driver supports a newer/different version of the I2C
	* registers/commands than the qt1070.c driver.
	* Don't let the similarity of the general driver structure fool you.
	*
	* For raw i2c access from userspace, use i2cset/i2cget
	* to poke at /dev/i2c-N devices.
	*/

	#include <linux/device.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/i2c.h>
	#include <linux/input.h>
	#include <linux/interrupt.h>
	#include <linux/slab.h>

	/* Maximum number of buttons supported */
	#define MAX_NUM_OF_BUTTONS 8

	/* Registers */
	#define REG_KEY1_THRESHOLD 0x02
	#define REG_KEY2_THRESHOLD 0x03
	#define REG_KEY3_THRESHOLD 0x04
	#define REG_KEY4_THRESHOLD 0x05

	#define REG_KEY1_REF_H 0x20
	#define REG_KEY1_REF_L 0x21
	#define REG_KEY2_REF_H 0x22
	#define REG_KEY2_REF_L 0x23
	#define REG_KEY3_REF_H 0x24
	#define REG_KEY3_REF_L 0x25
	#define REG_KEY4_REF_H 0x26
	#define REG_KEY4_REF_L 0x27

	#define REG_KEY1_DLT_H 0x30
	#define REG_KEY1_DLT_L 0x31
	#define REG_KEY2_DLT_H 0x32
	#define REG_KEY2_DLT_L 0x33
	#define REG_KEY3_DLT_H 0x34
	#define REG_KEY3_DLT_L 0x35
	#define REG_KEY4_DLT_H 0x36
	#define REG_KEY4_DLT_L 0x37

	#define REG_KEY_STATE 0x3C

	/*
	* @i2c_client: I2C slave device client pointer
	* @input: Input device pointer
	* @num_btn: Number of buttons
	* @keycodes: map of button# to KeyCode
	* @prev_btn: Previous key state to detect button "press" or "release"
	* @xfer_buf: I2C transfer buffer
	*/
	struct atmel_captouch_device {
	struct i2c_client *client;
	struct input_dev *input;
	u32 num_btn;
	u32 keycodes[MAX_NUM_OF_BUTTONS];
	u8 prev_btn;
	u8 xfer_buf[8] ____cacheline_aligned;
	};

	/*
	* Read from I2C slave device
	* The protocol is that the client has to provide both the register address
	* and the length, and while reading back the device would prepend the data
	* with address and length for verification.
	*/
	static int atmel_read(struct atmel_captouch_device *capdev,
	u8 reg, u8 *data, size_t len)
	{
	struct i2c_client *client = capdev->client;
	struct device *dev = &client->dev;
	struct i2c_msg msg[2];
	int err;

	if (len > sizeof(capdev->xfer_buf) - 2)
	return -EINVAL;

	capdev->xfer_buf[0] = reg;
	capdev->xfer_buf[1] = len;

	msg[0].addr = client->addr;
	msg[0].flags = 0;
	msg[0].buf = capdev->xfer_buf;
	msg[0].len = 2;

	msg[1].addr = client->addr;
	msg[1].flags = I2C_M_RD;
	msg[1].buf = capdev->xfer_buf;
	msg[1].len = len + 2;

	err = i2c_transfer(client->adapter, msg, ARRAY_SIZE(msg));
	if (err != ARRAY_SIZE(msg))
	return err < 0 ? err : -EIO;

	if (capdev->xfer_buf[0] != reg) {
	dev_err(dev,
	"I2C read error: register address does not match (%#02x vs %02x)\n",
	capdev->xfer_buf[0], reg);
	return -ECOMM;
	}

	memcpy(data, &capdev->xfer_buf[2], len);

	return 0;
	}

	/*
	* Handle interrupt and report the key changes to the input system.
	* Multi-touch can be supported; however, it really depends on whether
	* the device can multi-touch.
	*/
	static irqreturn_t atmel_captouch_isr(int irq, void *data)
	{
	struct atmel_captouch_device *capdev = data;
	struct device *dev = &capdev->client->dev;
	int error;
	int i;
	u8 new_btn;
	u8 changed_btn;

	error = atmel_read(capdev, REG_KEY_STATE, &new_btn, 1);
	if (error) {
	dev_err(dev, "failed to read button state: %d\n", error);
	goto out;
	}

	dev_dbg(dev, "%s: button state %#02x\n", __func__, new_btn);

	changed_btn = new_btn ^ capdev->prev_btn;
	capdev->prev_btn = new_btn;

	for (i = 0; i < capdev->num_btn; i++) {
	if (changed_btn & BIT(i))
	input_report_key(capdev->input,
	capdev->keycodes[i],
	new_btn & BIT(i));
	}

	input_sync(capdev->input);

	out:
	return IRQ_HANDLED;
	}

	/*
	* Probe function to setup the device, input system and interrupt
	*/
	static int atmel_captouch_probe(struct i2c_client *client)
	{
	struct atmel_captouch_device *capdev;
	struct device *dev = &client->dev;
	struct device_node *node;
	int i;
	int err;

	if (!i2c_check_functionality(client->adapter,
	I2C_FUNC_SMBUS_BYTE_DATA \|
	I2C_FUNC_SMBUS_WORD_DATA \|
	I2C_FUNC_SMBUS_I2C_BLOCK)) {
	dev_err(dev, "needed i2c functionality is not supported\n");
	return -EINVAL;
	}

	capdev = devm_kzalloc(dev, sizeof(*capdev), GFP_KERNEL);
	if (!capdev)
	return -ENOMEM;

	capdev->client = client;

	err = atmel_read(capdev, REG_KEY_STATE,
	&capdev->prev_btn, sizeof(capdev->prev_btn));
	if (err) {
	dev_err(dev, "failed to read initial button state: %d\n", err);
	return err;
	}

	capdev->input = devm_input_allocate_device(dev);
	if (!capdev->input) {
	dev_err(dev, "failed to allocate input device\n");
	return -ENOMEM;
	}

	capdev->input->id.bustype = BUS_I2C;
	capdev->input->id.product = 0x880A;
	capdev->input->id.version = 0;
	capdev->input->name = "ATMegaXX Capacitive Button Controller";
	__set_bit(EV_KEY, capdev->input->evbit);

	node = dev->of_node;
	if (!node) {
	dev_err(dev, "failed to find matching node in device tree\n");
	return -EINVAL;
	}

	if (of_property_read_bool(node, "autorepeat"))
	__set_bit(EV_REP, capdev->input->evbit);

	capdev->num_btn = of_property_count_u32_elems(node, "linux,keymap");
	if (capdev->num_btn > MAX_NUM_OF_BUTTONS)
	capdev->num_btn = MAX_NUM_OF_BUTTONS;

	err = of_property_read_u32_array(node, "linux,keycodes",
	capdev->keycodes,
	capdev->num_btn);
	if (err) {
	dev_err(dev,
	"failed to read linux,keycode property: %d\n", err);
	return err;
	}

	for (i = 0; i < capdev->num_btn; i++)
	__set_bit(capdev->keycodes[i], capdev->input->keybit);

	capdev->input->keycode = capdev->keycodes;
	capdev->input->keycodesize = sizeof(capdev->keycodes[0]);
	capdev->input->keycodemax = capdev->num_btn;

	err = input_register_device(capdev->input);
	if (err)
	return err;

	err = devm_request_threaded_irq(dev, client->irq,
	NULL, atmel_captouch_isr,
	IRQF_ONESHOT,
	"atmel_captouch", capdev);
	if (err) {
	dev_err(dev, "failed to request irq %d: %d\n",
	client->irq, err);
	return err;
	}

	return 0;
	}

	static const struct of_device_id atmel_captouch_of_id[] = {
	{
	.compatible = "atmel,captouch",
	},
	{ /* sentinel */ }
	};
	MODULE_DEVICE_TABLE(of, atmel_captouch_of_id);

	static const struct i2c_device_id atmel_captouch_id[] = {
	{ "atmel_captouch" },
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, atmel_captouch_id);

	static struct i2c_driver atmel_captouch_driver = {
	.probe = atmel_captouch_probe,
	.id_table = atmel_captouch_id,
	.driver = {
	.name = "atmel_captouch",
	.of_match_table = atmel_captouch_of_id,
	},
	};
	module_i2c_driver(atmel_captouch_driver);

	/* Module information */
	MODULE_AUTHOR("Hung-yu Wu <hywu@google.com>");
	MODULE_DESCRIPTION("Atmel ATmegaXX Capacitance Touch Sensor I2C Driver");
	MODULE_LICENSE("GPL v2");