trezor-firmware/embed/trezorhal/touch_t.h

#include <string.h>

#include "common.h"
#include "secbool.h"

#define TOUCH_ADDRESS       (0x38U << 1) // the HAL requires the 7-bit address to be shifted by one bit
#define TOUCH_PACKET_SIZE   7U
#define EVENT_PRESS_DOWN    0x00U
#define EVENT_CONTACT       0x80U
#define EVENT_LIFT_UP       0x40U
#define EVENT_NO_EVENT      0xC0U
#define GESTURE_NO_GESTURE  0x00U
#define X_POS_MSB (touch_data[3] & 0x0FU)
#define X_POS_LSB (touch_data[4])
#define Y_POS_MSB (touch_data[5] & 0x0FU)
#define Y_POS_LSB (touch_data[6])

static I2C_HandleTypeDef i2c_handle;

static void touch_default_pin_state(void) {
    // set power off and other pins as per section 3.5 of FT6236 datasheet
    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_10, GPIO_PIN_SET);    // CTP_ON/PB10 (active low) i.e.- CTPM power off when set/high/log 1
    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_6, GPIO_PIN_RESET);   // CTP_I2C_SCL/PB6
    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_7, GPIO_PIN_RESET);   // CTP_I2C_SDA/PB7
    HAL_GPIO_WritePin(GPIOC, GPIO_PIN_4, GPIO_PIN_RESET);   // CTP_INT/PC4 normally an input, but drive low as an output while powered off
    HAL_GPIO_WritePin(GPIOC, GPIO_PIN_5, GPIO_PIN_RESET);   // CTP_REST/PC5 (active low) i.e.- CTPM held in reset until released

    // set above pins to OUTPUT / NOPULL
    GPIO_InitTypeDef GPIO_InitStructure;

    GPIO_InitStructure.Mode  = GPIO_MODE_OUTPUT_PP;
    GPIO_InitStructure.Pull  = GPIO_NOPULL;
    GPIO_InitStructure.Speed = GPIO_SPEED_FREQ_LOW;
    GPIO_InitStructure.Pin   = GPIO_PIN_10 | GPIO_PIN_6 | GPIO_PIN_7;
    HAL_GPIO_Init(GPIOB, &GPIO_InitStructure);
    GPIO_InitStructure.Pin   = GPIO_PIN_4 | GPIO_PIN_5;
    HAL_GPIO_Init(GPIOC, &GPIO_InitStructure);

    // in-case power was on, or CTPM was active make sure to wait long enough
    // for these changes to take effect. a reset needs to be low for
    // a minimum of 5ms. also wait for power circuitry to stabilize (if it changed).
    HAL_Delay(100); // 100ms (being conservative)
}

static void touch_active_pin_state(void) {
    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_10, GPIO_PIN_RESET);  // CTP_ON/PB10
    HAL_Delay(10); // we need to wait until the circuit fully kicks-in

    GPIO_InitTypeDef GPIO_InitStructure;

    // configure CTP I2C SCL and SDA GPIO lines (PB6 & PB7)
    GPIO_InitStructure.Mode = GPIO_MODE_AF_OD;
    GPIO_InitStructure.Pull = GPIO_NOPULL;
    GPIO_InitStructure.Speed = GPIO_SPEED_FREQ_LOW; // I2C is a KHz bus and low speed is still good into the low MHz
    GPIO_InitStructure.Alternate = GPIO_AF4_I2C1;
    GPIO_InitStructure.Pin = GPIO_PIN_6 | GPIO_PIN_7;
    HAL_GPIO_Init(GPIOB, &GPIO_InitStructure);

    // PC4 capacitive touch panel module (CTPM) interrupt (INT) input
    GPIO_InitStructure.Mode  = GPIO_MODE_INPUT;
    GPIO_InitStructure.Pull  = GPIO_PULLUP;
    GPIO_InitStructure.Speed = GPIO_SPEED_FREQ_LOW;
    GPIO_InitStructure.Pin   = GPIO_PIN_4;
    HAL_GPIO_Init(GPIOC, &GPIO_InitStructure);

    HAL_GPIO_WritePin(GPIOC, GPIO_PIN_5, GPIO_PIN_SET); // release CTPM reset
    HAL_Delay(310); // "Time of starting to report point after resetting" min is 300ms, giving an extra 10ms
}

void touch_init(void) {
    touch_default_pin_state();
}

void HAL_I2C_MspInit(I2C_HandleTypeDef *hi2c) {
    // enable I2C clock
    __HAL_RCC_I2C1_CLK_ENABLE();
    // GPIO have already been initialised by touch_init
}

void HAL_I2C_MspDeInit(I2C_HandleTypeDef *hi2c) {
    __HAL_RCC_I2C1_CLK_DISABLE();
}

void touch_power_on(void) {
    if (i2c_handle.Instance) {
        return;
    }

    // turn on CTP circuitry
    touch_active_pin_state();
    HAL_Delay(50);

    // I2C device interface configuration
    i2c_handle.Instance = I2C1;
    i2c_handle.Init.ClockSpeed = 400000;
    i2c_handle.Init.DutyCycle = I2C_DUTYCYCLE_16_9;
    i2c_handle.Init.OwnAddress1 = 0xFE; // master
    i2c_handle.Init.AddressingMode = I2C_ADDRESSINGMODE_7BIT;
    i2c_handle.Init.DualAddressMode = I2C_DUALADDRESS_DISABLE;
    i2c_handle.Init.OwnAddress2 = 0;
    i2c_handle.Init.GeneralCallMode = I2C_GENERALCALL_DISABLE;
    i2c_handle.Init.NoStretchMode = I2C_NOSTRETCH_DISABLE;

    if (HAL_OK != HAL_I2C_Init(&i2c_handle)) {
        ensure(secfalse, NULL);
        return;
    }

    // set register 0xA4 G_MODE to interrupt polling mode (0x00). basically, CTPM keeps this input line (to PC4) low while a finger is on the screen.
    uint8_t touch_panel_config[] = {0xA4, 0x00};
    ensure(sectrue * (HAL_OK == HAL_I2C_Master_Transmit(&i2c_handle, TOUCH_ADDRESS, touch_panel_config, sizeof(touch_panel_config), 10)), NULL);
}

void touch_power_off(void) {
    if (i2c_handle.Instance) {
        HAL_I2C_DeInit(&i2c_handle);
        i2c_handle.Instance = NULL;
    }
    // turn off CTP circuitry
    HAL_Delay(50);
    touch_default_pin_state();
}

uint32_t touch_is_detected(void)
{
    // check the interrupt line coming in from the CTPM.
    // the line goes low when a touch event is actively detected.
    // reference section 1.2 of "Application Note for FT6x06 CTPM".
    // we configure the touch controller to use "interrupt polling mode".
    return GPIO_PIN_RESET == HAL_GPIO_ReadPin(GPIOC, GPIO_PIN_4);
}

uint32_t touch_read(void)
{
    static uint8_t touch_data[TOUCH_PACKET_SIZE], previous_touch_data[TOUCH_PACKET_SIZE];
    static uint32_t xy;
    static int touching;

    int last_packet = 0;
    if (!touch_is_detected()) {
        // only poll when the touch interrupt is active.
        // when it's inactive, we might need to read one last data packet to get to
        // the TOUCH_END event, which clears the `touching` flag.
        if (touching) {
            last_packet = 1;
        } else {
            return 0;
        }
    }

    uint8_t outgoing[] = {0x00}; // start reading from address 0x00
    if (HAL_OK != HAL_I2C_Master_Transmit(&i2c_handle, TOUCH_ADDRESS, outgoing, sizeof(outgoing), 1)) {
        return 0;
    }

    if (HAL_OK != HAL_I2C_Master_Receive(&i2c_handle, TOUCH_ADDRESS, touch_data, TOUCH_PACKET_SIZE, 1)) {
        return 0; // read failure
    }

    if (0 == memcmp(previous_touch_data, touch_data, TOUCH_PACKET_SIZE)) {
        return 0; // polled and got the same event again
    } else {
        memcpy(previous_touch_data, touch_data, TOUCH_PACKET_SIZE);
    }

    const uint32_t number_of_touch_points = touch_data[2] & 0x0F; // valid values are 0, 1, 2 (invalid 0xF before first touch) (tested with FT6206)
    const uint32_t event_flag = touch_data[3] & 0xC0;
    if (touch_data[1] == GESTURE_NO_GESTURE) {
        xy = touch_pack_xy((X_POS_MSB << 8) | X_POS_LSB, (Y_POS_MSB << 8) | Y_POS_LSB);
        if ((number_of_touch_points == 1) && (event_flag == EVENT_PRESS_DOWN)) {
            touching = 1;
            return TOUCH_START | xy;
        } else if ((number_of_touch_points == 1) && (event_flag == EVENT_CONTACT)) {
            return TOUCH_MOVE | xy;
        } else if ((number_of_touch_points == 0) && (event_flag == EVENT_LIFT_UP)) {
            touching = 0;
            return TOUCH_END | xy;
        }
    }

    if (last_packet) {
        // interrupt line is inactive, we didn't read valid touch data, and as far as
        // we know, we never sent a TOUCH_END event.
        touching = 0;
        return TOUCH_END | xy;
    }

    return 0;
}