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281 lines
7.0 KiB
281 lines
7.0 KiB
// 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 <[email protected]>"); |
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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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