266 lines
8.6 KiB
C
266 lines
8.6 KiB
C
/*
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* Copyright (c) 2023 Seppo Takalo
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#define DT_DRV_COMPAT xptek_xpt2046
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#include <zephyr/drivers/spi.h>
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#include <zephyr/input/input.h>
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#include <zephyr/kernel.h>
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#include <zephyr/logging/log.h>
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LOG_MODULE_REGISTER(xpt2046, CONFIG_INPUT_LOG_LEVEL);
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struct xpt2046_config {
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const struct spi_dt_spec bus;
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const struct gpio_dt_spec int_gpio;
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uint16_t min_x;
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uint16_t min_y;
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uint16_t max_x;
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uint16_t max_y;
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uint16_t threshold;
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uint16_t screen_size_x;
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uint16_t screen_size_y;
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uint16_t reads;
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};
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struct xpt2046_data {
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const struct device *dev;
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struct gpio_callback int_gpio_cb;
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struct k_work work;
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struct k_work_delayable dwork;
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uint8_t rbuf[9];
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uint32_t last_x;
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uint32_t last_y;
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bool pressed;
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};
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enum xpt2046_channel {
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CH_TEMP0 = 0,
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CH_Y,
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CH_VBAT,
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CH_Z1,
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CH_Z2,
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CH_X,
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CH_AUXIN,
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CH_TEMP1
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};
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struct measurement {
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uint32_t x;
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uint32_t y;
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uint32_t z;
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};
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#define START BIT(7)
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#define CHANNEL(ch) ((ch & 0x7) << 4)
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#define MODE_8_BIT BIT(3)
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#define SINGLE_ENDED BIT(2)
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#define POWER_OFF 0
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#define POWER_ON 0x03
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#define CONVERT_U16(buf, idx) ((uint16_t)((buf[idx] & 0x7f) << 5) | (buf[idx + 1] >> 3))
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/* Read all Z1, X, Y, Z2 channels using 16 Clocks-per-Conversion mode.
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* See the manual https://www.waveshare.com/w/upload/9/98/XPT2046-EN.pdf for details.
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* Each follow-up command interleaves with previous conversion.
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* So first command starts at byte 0. Second command starts at byte 2.
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*/
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static uint8_t tbuf[9] = {
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[0] = START | CHANNEL(CH_Z1) | POWER_ON,
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[2] = START | CHANNEL(CH_Z2) | POWER_ON,
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[4] = START | CHANNEL(CH_X) | POWER_ON,
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[6] = START | CHANNEL(CH_Y) | POWER_OFF,
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};
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static void xpt2046_isr_handler(const struct device *dev, struct gpio_callback *cb, uint32_t pins)
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{
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struct xpt2046_data *data = CONTAINER_OF(cb, struct xpt2046_data, int_gpio_cb);
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const struct xpt2046_config *config = data->dev->config;
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gpio_remove_callback(config->int_gpio.port, &data->int_gpio_cb);
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k_work_submit(&data->work);
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}
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static int xpt2046_read_and_cumulate(const struct spi_dt_spec *bus, const struct spi_buf_set *tx,
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const struct spi_buf_set *rx, struct measurement *meas)
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{
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int ret = spi_transceive_dt(bus, tx, rx);
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if (ret < 0) {
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LOG_ERR("spi_transceive() %d\n", ret);
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return ret;
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}
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uint8_t *buf = rx->buffers->buf;
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meas->z += CONVERT_U16(buf, 1) + 4096 - CONVERT_U16(buf, 3);
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meas->x += CONVERT_U16(buf, 5);
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meas->y += CONVERT_U16(buf, 7);
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return 0;
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}
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static void xpt2046_release_handler(struct k_work *kw)
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{
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struct k_work_delayable *dw = k_work_delayable_from_work(kw);
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struct xpt2046_data *data = CONTAINER_OF(dw, struct xpt2046_data, dwork);
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struct xpt2046_config *config = (struct xpt2046_config *)data->dev->config;
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if (!data->pressed) {
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return;
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}
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/* Check if touch is still pressed */
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if (gpio_pin_get_dt(&config->int_gpio) == 0) {
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data->pressed = false;
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input_report_key(data->dev, INPUT_BTN_TOUCH, 0, true, K_FOREVER);
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} else {
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/* Re-check later */
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k_work_reschedule(&data->dwork, K_MSEC(10));
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}
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}
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static void xpt2046_work_handler(struct k_work *kw)
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{
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struct xpt2046_data *data = CONTAINER_OF(kw, struct xpt2046_data, work);
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struct xpt2046_config *config = (struct xpt2046_config *)data->dev->config;
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int ret;
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const struct spi_buf txb = {.buf = tbuf, .len = sizeof(tbuf)};
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const struct spi_buf rxb = {.buf = data->rbuf, .len = sizeof(data->rbuf)};
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const struct spi_buf_set tx_bufs = {.buffers = &txb, .count = 1};
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const struct spi_buf_set rx_bufs = {.buffers = &rxb, .count = 1};
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/* Run number of reads and calculate average */
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int rounds = config->reads;
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struct measurement meas = {0};
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for (int i = 0; i < rounds; i++) {
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if (xpt2046_read_and_cumulate(&config->bus, &tx_bufs, &rx_bufs, &meas) != 0) {
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return;
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}
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}
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meas.x /= rounds;
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meas.y /= rounds;
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meas.z /= rounds;
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/* Calculate Xp = M * Xt + C using fixed point aritchmetics, where
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* Xp is the point in screen coordinates, Xt is the touch coordinates.
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* Use signed int32_t for calculation to ensure that we cover the roll-over to negative
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* values and return zero instead.
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*/
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int32_t mx = (config->screen_size_x << 16) / (config->max_x - config->min_x);
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int32_t cx = (config->screen_size_x << 16) - mx * config->max_x;
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int32_t x = mx * meas.x + cx;
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x = (x < 0 ? 0 : x) >> 16;
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int32_t my = (config->screen_size_y << 16) / (config->max_y - config->min_y);
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int32_t cy = (config->screen_size_y << 16) - my * config->max_y;
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int32_t y = my * meas.y + cy;
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y = (y < 0 ? 0 : y) >> 16;
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bool pressed = meas.z > config->threshold;
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/* Don't send any other than "pressed" events.
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* releasing seem to cause just random noise
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*/
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if (pressed) {
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LOG_DBG("raw: x=%4u y=%4u ==> x=%4d y=%4d", meas.x, meas.y, x, y);
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input_report_abs(data->dev, INPUT_ABS_X, x, false, K_FOREVER);
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input_report_abs(data->dev, INPUT_ABS_Y, y, false, K_FOREVER);
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input_report_key(data->dev, INPUT_BTN_TOUCH, 1, true, K_FOREVER);
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data->last_x = x;
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data->last_y = y;
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data->pressed = pressed;
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/* Ensure that we send released event */
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k_work_reschedule(&data->dwork, K_MSEC(100));
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}
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ret = gpio_add_callback(config->int_gpio.port, &data->int_gpio_cb);
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if (ret < 0) {
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LOG_ERR("Could not set gpio callback");
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return;
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}
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}
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static int xpt2046_init(const struct device *dev)
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{
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int r;
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const struct xpt2046_config *config = dev->config;
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struct xpt2046_data *data = dev->data;
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if (!spi_is_ready_dt(&config->bus)) {
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LOG_ERR("SPI controller device not ready");
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return -ENODEV;
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}
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data->dev = dev;
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k_work_init(&data->work, xpt2046_work_handler);
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k_work_init_delayable(&data->dwork, xpt2046_release_handler);
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if (!gpio_is_ready_dt(&config->int_gpio)) {
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LOG_ERR("Interrupt GPIO controller device not ready");
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return -ENODEV;
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}
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r = gpio_pin_configure_dt(&config->int_gpio, GPIO_INPUT);
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if (r < 0) {
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LOG_ERR("Could not configure interrupt GPIO pin");
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return r;
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}
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r = gpio_pin_interrupt_configure_dt(&config->int_gpio, GPIO_INT_EDGE_TO_ACTIVE);
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if (r < 0) {
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LOG_ERR("Could not configure interrupt GPIO interrupt.");
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return r;
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}
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gpio_init_callback(&data->int_gpio_cb, xpt2046_isr_handler, BIT(config->int_gpio.pin));
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r = gpio_add_callback(config->int_gpio.port, &data->int_gpio_cb);
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if (r < 0) {
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LOG_ERR("Could not set gpio callback");
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return r;
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}
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LOG_INF("Init '%s' device", dev->name);
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return 0;
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}
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#define XPT2046_INIT(index) \
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static const struct xpt2046_config xpt2046_config_##index = { \
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.bus = SPI_DT_SPEC_INST_GET( \
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index, SPI_OP_MODE_MASTER | SPI_TRANSFER_MSB | SPI_WORD_SET(8), 0), \
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.int_gpio = GPIO_DT_SPEC_INST_GET(index, int_gpios), \
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.min_x = DT_INST_PROP(index, min_x), \
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.min_y = DT_INST_PROP(index, min_y), \
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.max_x = DT_INST_PROP(index, max_x), \
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.max_y = DT_INST_PROP(index, max_y), \
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.threshold = DT_INST_PROP(index, z_threshold), \
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.screen_size_x = DT_INST_PROP(index, touchscreen_size_x), \
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.screen_size_y = DT_INST_PROP(index, touchscreen_size_y), \
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.reads = DT_INST_PROP(index, reads), \
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}; \
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static struct xpt2046_data xpt2046_data_##index; \
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DEVICE_DT_INST_DEFINE(index, xpt2046_init, NULL, &xpt2046_data_##index, \
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&xpt2046_config_##index, POST_KERNEL, CONFIG_INPUT_INIT_PRIORITY, \
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NULL); \
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BUILD_ASSERT(DT_INST_PROP(index, min_x) < DT_INST_PROP(index, max_x), \
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"min_x must be less than max_x"); \
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BUILD_ASSERT(DT_INST_PROP(index, min_y) < DT_INST_PROP(index, max_y), \
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"min_y must be less than max_y"); \
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BUILD_ASSERT(DT_INST_PROP(index, z_threshold) > 10, "Too small threshold"); \
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BUILD_ASSERT(DT_INST_PROP(index, touchscreen_size_x) > 1 && \
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DT_INST_PROP(index, touchscreen_size_y) > 1, \
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"Screen size undefined"); \
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BUILD_ASSERT(DT_INST_PROP(index, reads) > 0, "Number of reads must be at least one");
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DT_INST_FOREACH_STATUS_OKAY(XPT2046_INIT)
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