diff options
Diffstat (limited to 'drivers/input/misc/atmel_captouch.c')
| -rw-r--r-- | drivers/input/misc/atmel_captouch.c | 289 |
1 files changed, 289 insertions, 0 deletions
diff --git a/drivers/input/misc/atmel_captouch.c b/drivers/input/misc/atmel_captouch.c new file mode 100644 index 000000000..c4c0f4bb7 --- /dev/null +++ b/drivers/input/misc/atmel_captouch.c @@ -0,0 +1,289 @@ +/* + * 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"); |