| /* |
| * 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; |
| |
| 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"); |