// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Atmel Atmegaxx Capacitive Touch Button Driver
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*
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* Copyright (C) 2016 Google, inc.
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*/
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/*
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* It's irrelevant that the HW used to develop captouch driver is based
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* on Atmega88PA part and uses QtouchADC parts for sensing touch.
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* Calling this driver "captouch" is an arbitrary way to distinguish
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* the protocol this driver supported by other atmel/qtouch drivers.
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*
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* Captouch driver supports a newer/different version of the I2C
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* registers/commands than the qt1070.c driver.
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* Don't let the similarity of the general driver structure fool you.
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*
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* For raw i2c access from userspace, use i2cset/i2cget
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* to poke at /dev/i2c-N devices.
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*/
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#include <linux/device.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/i2c.h>
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#include <linux/input.h>
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#include <linux/interrupt.h>
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#include <linux/slab.h>
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/* Maximum number of buttons supported */
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#define MAX_NUM_OF_BUTTONS 8
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/* Registers */
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#define REG_KEY1_THRESHOLD 0x02
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#define REG_KEY2_THRESHOLD 0x03
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#define REG_KEY3_THRESHOLD 0x04
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#define REG_KEY4_THRESHOLD 0x05
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#define REG_KEY1_REF_H 0x20
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#define REG_KEY1_REF_L 0x21
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#define REG_KEY2_REF_H 0x22
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#define REG_KEY2_REF_L 0x23
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#define REG_KEY3_REF_H 0x24
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#define REG_KEY3_REF_L 0x25
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#define REG_KEY4_REF_H 0x26
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#define REG_KEY4_REF_L 0x27
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#define REG_KEY1_DLT_H 0x30
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#define REG_KEY1_DLT_L 0x31
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#define REG_KEY2_DLT_H 0x32
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#define REG_KEY2_DLT_L 0x33
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#define REG_KEY3_DLT_H 0x34
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#define REG_KEY3_DLT_L 0x35
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#define REG_KEY4_DLT_H 0x36
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#define REG_KEY4_DLT_L 0x37
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#define REG_KEY_STATE 0x3C
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/*
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* @i2c_client: I2C slave device client pointer
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* @input: Input device pointer
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* @num_btn: Number of buttons
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* @keycodes: map of button# to KeyCode
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* @prev_btn: Previous key state to detect button "press" or "release"
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* @xfer_buf: I2C transfer buffer
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*/
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struct atmel_captouch_device {
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struct i2c_client *client;
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struct input_dev *input;
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u32 num_btn;
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u32 keycodes[MAX_NUM_OF_BUTTONS];
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u8 prev_btn;
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u8 xfer_buf[8] ____cacheline_aligned;
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};
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/*
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* Read from I2C slave device
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* The protocol is that the client has to provide both the register address
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* and the length, and while reading back the device would prepend the data
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* with address and length for verification.
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*/
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static int atmel_read(struct atmel_captouch_device *capdev,
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u8 reg, u8 *data, size_t len)
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{
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struct i2c_client *client = capdev->client;
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struct device *dev = &client->dev;
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struct i2c_msg msg[2];
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int err;
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if (len > sizeof(capdev->xfer_buf) - 2)
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return -EINVAL;
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capdev->xfer_buf[0] = reg;
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capdev->xfer_buf[1] = len;
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msg[0].addr = client->addr;
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msg[0].flags = 0;
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msg[0].buf = capdev->xfer_buf;
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msg[0].len = 2;
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msg[1].addr = client->addr;
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msg[1].flags = I2C_M_RD;
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msg[1].buf = capdev->xfer_buf;
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msg[1].len = len + 2;
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err = i2c_transfer(client->adapter, msg, ARRAY_SIZE(msg));
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if (err != ARRAY_SIZE(msg))
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return err < 0 ? err : -EIO;
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if (capdev->xfer_buf[0] != reg) {
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dev_err(dev,
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"I2C read error: register address does not match (%#02x vs %02x)\n",
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capdev->xfer_buf[0], reg);
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return -ECOMM;
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}
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memcpy(data, &capdev->xfer_buf[2], len);
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return 0;
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}
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/*
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* Handle interrupt and report the key changes to the input system.
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* Multi-touch can be supported; however, it really depends on whether
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* the device can multi-touch.
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*/
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static irqreturn_t atmel_captouch_isr(int irq, void *data)
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{
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struct atmel_captouch_device *capdev = data;
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struct device *dev = &capdev->client->dev;
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int error;
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int i;
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u8 new_btn;
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u8 changed_btn;
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error = atmel_read(capdev, REG_KEY_STATE, &new_btn, 1);
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if (error) {
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dev_err(dev, "failed to read button state: %d\n", error);
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goto out;
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}
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dev_dbg(dev, "%s: button state %#02x\n", __func__, new_btn);
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changed_btn = new_btn ^ capdev->prev_btn;
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capdev->prev_btn = new_btn;
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for (i = 0; i < capdev->num_btn; i++) {
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if (changed_btn & BIT(i))
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input_report_key(capdev->input,
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capdev->keycodes[i],
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new_btn & BIT(i));
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}
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input_sync(capdev->input);
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out:
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return IRQ_HANDLED;
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}
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/*
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* Probe function to setup the device, input system and interrupt
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*/
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static int atmel_captouch_probe(struct i2c_client *client,
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const struct i2c_device_id *id)
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{
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struct atmel_captouch_device *capdev;
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struct device *dev = &client->dev;
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struct device_node *node;
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int i;
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int err;
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if (!i2c_check_functionality(client->adapter,
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I2C_FUNC_SMBUS_BYTE_DATA |
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I2C_FUNC_SMBUS_WORD_DATA |
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I2C_FUNC_SMBUS_I2C_BLOCK)) {
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dev_err(dev, "needed i2c functionality is not supported\n");
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return -EINVAL;
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}
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capdev = devm_kzalloc(dev, sizeof(*capdev), GFP_KERNEL);
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if (!capdev)
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return -ENOMEM;
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capdev->client = client;
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err = atmel_read(capdev, REG_KEY_STATE,
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&capdev->prev_btn, sizeof(capdev->prev_btn));
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if (err) {
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dev_err(dev, "failed to read initial button state: %d\n", err);
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return err;
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}
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capdev->input = devm_input_allocate_device(dev);
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if (!capdev->input) {
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dev_err(dev, "failed to allocate input device\n");
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return -ENOMEM;
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}
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capdev->input->id.bustype = BUS_I2C;
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capdev->input->id.product = 0x880A;
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capdev->input->id.version = 0;
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capdev->input->name = "ATMegaXX Capacitive Button Controller";
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__set_bit(EV_KEY, capdev->input->evbit);
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node = dev->of_node;
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if (!node) {
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dev_err(dev, "failed to find matching node in device tree\n");
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return -EINVAL;
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}
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if (of_property_read_bool(node, "autorepeat"))
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__set_bit(EV_REP, capdev->input->evbit);
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capdev->num_btn = of_property_count_u32_elems(node, "linux,keymap");
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if (capdev->num_btn > MAX_NUM_OF_BUTTONS)
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capdev->num_btn = MAX_NUM_OF_BUTTONS;
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err = of_property_read_u32_array(node, "linux,keycodes",
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capdev->keycodes,
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capdev->num_btn);
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if (err) {
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dev_err(dev,
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"failed to read linux,keycode property: %d\n", err);
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return err;
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}
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for (i = 0; i < capdev->num_btn; i++)
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__set_bit(capdev->keycodes[i], capdev->input->keybit);
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capdev->input->keycode = capdev->keycodes;
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capdev->input->keycodesize = sizeof(capdev->keycodes[0]);
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capdev->input->keycodemax = capdev->num_btn;
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err = input_register_device(capdev->input);
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if (err)
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return err;
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err = devm_request_threaded_irq(dev, client->irq,
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NULL, atmel_captouch_isr,
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IRQF_ONESHOT,
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"atmel_captouch", capdev);
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if (err) {
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dev_err(dev, "failed to request irq %d: %d\n",
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client->irq, err);
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return err;
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}
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return 0;
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}
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#ifdef CONFIG_OF
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static const struct of_device_id atmel_captouch_of_id[] = {
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{
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.compatible = "atmel,captouch",
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},
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{ /* sentinel */ }
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};
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MODULE_DEVICE_TABLE(of, atmel_captouch_of_id);
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#endif
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static const struct i2c_device_id atmel_captouch_id[] = {
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{ "atmel_captouch", 0 },
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{ }
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};
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MODULE_DEVICE_TABLE(i2c, atmel_captouch_id);
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static struct i2c_driver atmel_captouch_driver = {
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.probe = atmel_captouch_probe,
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.id_table = atmel_captouch_id,
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.driver = {
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.name = "atmel_captouch",
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.of_match_table = of_match_ptr(atmel_captouch_of_id),
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},
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};
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module_i2c_driver(atmel_captouch_driver);
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/* Module information */
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MODULE_AUTHOR("Hung-yu Wu <hywu@google.com>");
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MODULE_DESCRIPTION("Atmel ATmegaXX Capacitance Touch Sensor I2C Driver");
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MODULE_LICENSE("GPL v2");
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