//---
// gint:touch:i2c - I2C driver
//---
#include <string.h>

#include <gint/defs/attributes.h>
#include <gint/defs/types.h>
#include <gint/defs/call.h>
#include <gint/cpu.h>
#include <gint/intc.h>
#include <gint/config.h>

#if GINT_HW_CP

#include "./i2c.h"

//---
// Internals
//---

/* __i2c_request - internal I2C request information */
volatile struct i2c_request_info __i2c_request;

/* i2c_hw_enable() - enable the I2C peripheral and configure the clock
 *
 * notes
 *   Clock configuration are the same used by Casio. Investigation must be
 *   made to ensure overclock/underclock validity */
static void _i2c_hw_enable(void)
{
    SH7305_I2C.ICCR.ICE = 1;
    while(true) {
        if (SH7305_I2C.ICSR.BUSY == 0)
            break;
    }
    SH7305_I2C.ICCL = 0x29;
    SH7305_I2C.ICCH = 0x22;
}

/* i2c_hw_start_operation() - start I2C operation
 *
 * notes
 *   Enable only data transmit and arbitration lost interrupt then perform
 *   a start condition (0x94) */
static void _i2c_hw_start_operation(void)
{
    SH7305_I2C.ICIC.ALE     = 1;
    SH7305_I2C.ICIC.TACKE   = 1;
    SH7305_I2C.ICIC.WAITE   = 0;
    SH7305_I2C.ICIC.DTEE    = 1;
    SH7305_I2C.ICCR.byte    = 0x94;
}

/* i2c_request_await() - await async operation */
static int _i2c_request_await(void)
{
    int status;

    while (true)
    {
        cpu_atomic_start();
        status = (__i2c_request.status == I2C_REQ_STATUS_FINISHED);
        cpu_atomic_end();
        if (status)
            break;
        __asm__ volatile ("sleep");
    }
    return 0;
}

//---
// Public
//---

/* i2c_reg_select() - select a register */
int i2c_reg_select(int reg)
{
    cpu_atomic_start();
    _i2c_hw_enable();

    __i2c_request.mode                  = I2C_REQ_MODE_REG_SELECT;
    __i2c_request.target_register       = reg;
    __i2c_request.buffer                = NULL;
    __i2c_request.buffer_size           = 0;
    __i2c_request.buffer_size_remaning  = 0;
    __i2c_request.buffer_cursor         = 0;
    __i2c_request.status                = I2C_REQ_STATUS_START;
    __i2c_request.state                 = I2C_REQ_STATE_START;

    cpu_atomic_end();
    _i2c_hw_start_operation();
    return _i2c_request_await();
}

/* i2c_reg_read() - register read operation */
int i2c_reg_read(int reg, void *buffer, size_t size)
{
    if (buffer == NULL)
        return -1;
    if (size == 0)
        return -2;

    cpu_atomic_start();
    _i2c_hw_enable();

    __i2c_request.mode                  = I2C_REQ_MODE_REG_READ;
    __i2c_request.target_register       = reg;
    __i2c_request.buffer                = buffer;
    __i2c_request.buffer_size           = size;
    __i2c_request.buffer_size_remaning  = size;
    __i2c_request.buffer_cursor         = 0;
    __i2c_request.status                = I2C_REQ_STATUS_START;
    __i2c_request.state                 = I2C_REQ_STATE_START;

    cpu_atomic_end();
    _i2c_hw_start_operation();
    return _i2c_request_await();
}

/* i2c_read_stream() - "stream" read operation (skip reg selection) */
int i2c_read_stream(void *buffer, size_t size)
{
    if (buffer == NULL)
        return -1;
    if (size == 0)
        return -2;

    cpu_atomic_start();
    _i2c_hw_enable();

    __i2c_request.mode                  = I2C_REQ_MODE_READ_STREAM;
    __i2c_request.target_register       = 0x00;
    __i2c_request.buffer                = buffer;
    __i2c_request.buffer_size           = size;
    __i2c_request.buffer_size_remaning  = size;
    __i2c_request.buffer_cursor         = 0;
    __i2c_request.status                = I2C_REQ_STATUS_START;
    __i2c_request.state                 = I2C_REQ_STATE_START;

    cpu_atomic_end();
    _i2c_hw_start_operation();
    return _i2c_request_await();
}

//---
// Driver and state management
//---

#include <gint/mpu/power.h>
#include <gint/mpu/pfc.h>
#include <gint/mpu/intc.h>


/* i2c_hpowered() - check if the module is powered */
bool i2c_hpowered(void)
{
    return (SH7305_POWER.MSTPCR2.I2C == 0);
}

/* i2c_hpoweron() - power on the module */
void i2c_hpoweron(void)
{
    SH7305_POWER.MSTPCR2.I2C = 0;
    SH7305_I2C.ICCR.ICE = 0;
    SH7305_I2C.ICDR = 0;
    SH7305_I2C.ICCL = 0x00;
    SH7305_I2C.ICCH = 0x00;
}

/* i2c_hpoweroff() - power on the module */
void i2c_hpoweroff(void)
{
    SH7305_POWER.MSTPCR2.I2C = 1;
}

/* i2c_hsave() - save hardware information */
void i2c_hsave(touch_state_t *state)
{
    state->PJCR = SH7305_PFC.PJCR.word;
    state->ICCR = SH7305_I2C.ICCR.byte;
    state->ICIC = SH7305_I2C.ICIC.byte;
    state->ICCL = SH7305_I2C.ICCL;
    state->ICCH = SH7305_I2C.ICCH;
}

/* i2c_hrestore() - restore hardware information */
void i2c_hrestore(touch_state_t *state)
{
    SH7305_I2C.ICCH      = state->ICCH;
    SH7305_I2C.ICCL      = state->ICCL;
    SH7305_I2C.ICIC.byte = state->ICIC;
    SH7305_I2C.ICCR.byte = state->ICCR;
    SH7305_PFC.PJCR.word = state->PJCR;
}

/* i2c_configure() - configure and install interrupt handlers */
void i2c_configure(void)
{
    extern void i2c_inth_tack(void);
    extern void i2c_inth_wait(void);
    extern void i2c_inth_trans(void);
    extern void i2c_inth_al(void);

    // install I2C handler
    intc_handler_function(0xe00, GINT_CALL(i2c_inth_al));
    intc_handler_function(0xe20, GINT_CALL(i2c_inth_tack));
    intc_handler_function(0xe40, GINT_CALL(i2c_inth_wait));
    intc_handler_function(0xe60, GINT_CALL(i2c_inth_trans));

    // configure I2C PIN
    SH7305_PFC.PJCR.P5MD = 0b00;
    SH7305_PFC.PJCR.P4MD = 0b00;

    // configure I2C module
    SH7305_I2C.ICCR.ICE  = 0;
    SH7305_I2C.ICDR      = 0;
    SH7305_I2C.ICCL      = 0x00;
    SH7305_I2C.ICCH      = 0x00;
    SH7305_I2C.ICSR.byte = 0x00;
    SH7305_I2C.ICIC.byte = 0x00;

    // init high-level driver information
    memset((void*)&__i2c_request, 0x00, sizeof(struct i2c_request_info));
    __i2c_request.status = I2C_REQ_STATUS_FINISHED;

    // Enable interrupt
    intc_priority(INTC_I2C_AL,   15);
    intc_priority(INTC_I2C_TACK, 15);
    intc_priority(INTC_I2C_WAIT, 15);
    intc_priority(INTC_I2C_DTE,  15);
}

/* i2c_unbind() - unbind from gint to casio */
void i2c_unbind(void)
{
    _i2c_request_await();
}

/* i2c_funbind() - funbind from casio to gint */
void i2c_funbind(void)
{
    if (i2c_hpowered() == false)
        return;
    // fixme : avoid force terminate
    //  We cannot easily know the state of Casio's driver since they use
    //  an state machine to work, and finding the current state require a
    //  lot of hardcoded OS-specific offsets information. So, for now,
    //  force terminate the transaction and disable the module to avoid
    //  any error
    SH7305_I2C.ICCR.ICE = 0;
    SH7305_I2C.ICDR = 0;
}

#endif /* GINT_HW_CP */