Input: add Atmel Captouch Button driver (b06d43f7) · Commits · e / devices / android_kernel_teracube_emerald

Documentation/devicetree/bindings/input/atmel,captouch.txt

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		Device tree bindings for Atmel capacitive touch device, typically
		an Atmel touch sensor connected to AtmegaXX MCU running firmware
		based on Qtouch library.

		The node for this device must be a child of a I2C controller node, as the
		device communicates via I2C.

		Required properties:

		compatible: Must be "atmel,captouch".
		reg: The I2C slave address of the device.
		interrupts: Property describing the interrupt line the device
		is connected to. The device only has one interrupt
		source.
		linux,keycodes: Specifies an array of numeric keycode values to
		be used for reporting button presses. The array can
		contain up to 8 entries.

		Optional properties:

		autorepeat: Enables the Linux input system's autorepeat
		feature on the input device.

		Example:

		atmel-captouch@51 {
		compatible = "atmel,captouch";
		reg = <0x51>;
		interrupt-parent = <&tlmm>;
		interrupts = <67 IRQ_TYPE_EDGE_FALLING>;
		linux,keycodes = <BTN_0>, <BTN_1>,
		<BTN_2>, <BTN_3>,
		<BTN_4>, <BTN_5>,
		<BTN_6>, <BTN_7>;
		autorepeat;
		};

drivers/input/misc/Kconfig

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		@@ -82,6 +82,19 @@ config INPUT_ARIZONA_HAPTICS
		To compile this driver as a module, choose M here: the
		module will be called arizona-haptics.

		config INPUT_ATMEL_CAPTOUCH
		tristate "Atmel Capacitive Touch Button Driver"
		depends on OF \|\| COMPILE_TEST
		help
		Say Y here if an Atmel Capacitive Touch Button device which
		implements "captouch" protocol is connected to I2C bus. Typically
		this device consists of Atmel Touch sensor controlled by AtMegaXX
		MCU running firmware based on Qtouch library.
		One should find "atmel,captouch" node in the board specific DTS.

		To compile this driver as a module, choose M here: the
		module will be called atmel_captouch.

		config INPUT_BMA150
		tristate "BMA150/SMB380 acceleration sensor support"
		depends on I2C

drivers/input/misc/Makefile

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		@@ -17,6 +17,7 @@ obj-$(CONFIG_INPUT_APANEL) += apanel.o
		obj-$(CONFIG_INPUT_ARIZONA_HAPTICS) += arizona-haptics.o
		obj-$(CONFIG_INPUT_ATI_REMOTE2) += ati_remote2.o
		obj-$(CONFIG_INPUT_ATLAS_BTNS) += atlas_btns.o
		obj-$(CONFIG_INPUT_ATMEL_CAPTOUCH) += atmel_captouch.o
		obj-$(CONFIG_INPUT_BFIN_ROTARY) += bfin_rotary.o
		obj-$(CONFIG_INPUT_BMA150) += bma150.o
		obj-$(CONFIG_INPUT_CM109) += cm109.o

drivers/input/misc/atmel_captouch.c

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		/*
		* Atmel Atmegaxx Capacitive Touch Button Driver
		*
		* Copyright (C) 2016 Google, inc.
		*
		* This software is licensed under the terms of the GNU General Public
		* License version 2, as published by the Free Software Foundation, and
		* may be copied, distributed, and modified under those terms.
		*
		* This program is distributed in the hope that it will be useful,
		* but WITHOUT ANY WARRANTY; without even the implied warranty of
		* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
		* GNU General Public License for more details.
		*/

		/*
		* 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,
		const struct i2c_device_id *id)
		{
		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;
		i2c_set_clientdata(client, capdev);

		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;
		}

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

		static const struct i2c_device_id atmel_captouch_id[] = {
		{ "atmel_captouch", 0 },
		{ }
		};
		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 = of_match_ptr(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");