#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/kobject.h>
#include <linux/sysfs.h>
#include <linux/acpi.h>
#include <linux/io.h>
#include <linux/delay.h>
#include "gpioregs.h"

extern struct kobject *hwmon_kobj;


/* Helper functions for IO access */
static uint8_t hwm_read_reg(uint16_t hwm_base, uint8_t reg)
{
    outb(reg, hwm_base + HWM_INDEX_OFFSET);
    return inb(hwm_base + HWM_DATA_OFFSET);
}

static void hwm_write_reg(uint16_t hwm_base, uint8_t reg, uint8_t val)
{
    outb(reg, hwm_base + HWM_INDEX_OFFSET);
    outb(val, hwm_base + HWM_DATA_OFFSET);
}

static uint8_t hwm_read_reg_retry(uint16_t hwm_base, uint8_t reg)
{
    uint8_t v = hwm_read_reg(hwm_base, reg);
    if (v == 0xFF) {
        v = hwm_read_reg(hwm_base, reg);
    }
    return v;
}

static int vin_raw_to_volt(uint8_t raw, int r_top_kohm, int r_bottom_kohm)
{
    int vm = raw * 11;
    if (r_top_kohm > 0 && r_bottom_kohm > 0) {
        vm = (vm * (r_top_kohm + r_bottom_kohm)) / r_bottom_kohm;
    }
    return vm;
}

static int ec_raw_to_volt(uint8_t raw, int r_top_kohm, int r_bottom_kohm)
{
    int vm = raw * 12; /* EC unit: 10mV */
    vm = (vm * (r_top_kohm + r_bottom_kohm)) / r_bottom_kohm;
    return vm ;
}


static int ec_wait_ibf(void)
{
    int i = 0;
    while (inb(EC_CMD_PORT) & EC_IBF) {
        if (++i > TIMEOUT_LOOPS) {
            printk("Error: EC IBF Timeout!\n");
            return -1;
        }
        udelay(1);
    }
    return 0;
}

static int ec_wait_obf(void)
{
    int i = 0;
    while (!(inb(EC_CMD_PORT) & EC_OBF)) {
        if (++i > TIMEOUT_LOOPS) {
            printk("Error: EC OBF Timeout!\n");
            return -1;
        }
        udelay(1);
    }
    return 0;
}


static int wait_ibf(void)
{
    int i = 0;
    while (inb(EC_CMD_PORT) & EC_IBF)
    {
        if (++i > TIMEOUT_LOOPS)
        {
            return -1;
        }
        udelay(1);
    }
    return 0;
}

static int wait_obf(void)
{
    int i = 0;
    while (!(inb(EC_CMD_PORT) & EC_OBF))
    {
        if (++i > TIMEOUT_LOOPS)
        {
            return -1;
        }
        udelay(1);
    }
    return 0;
}

static int ec_read_ram(uint8_t offset, uint8_t *data)
{
    if (wait_ibf() < 0)
        return -1;
    outb(CMD_READ_RAM, EC_CMD_PORT);

    if (wait_ibf() < 0)
        return -1;
    outb(offset, EC_DATA_PORT);

    if (wait_obf() < 0)
        return -1;
    *data = inb(EC_DATA_PORT);

    return 0;
}

static int ec_write_ram(uint8_t offset, uint8_t data)
{
    if (wait_ibf() < 0)
        return -1;
    outb(CMD_WRITE_RAM, EC_CMD_PORT);

    if (wait_ibf() < 0)
        return -1;
    outb(offset, EC_DATA_PORT);

    if (wait_ibf() < 0)
        return -1;
    outb(data, EC_DATA_PORT);

    return 0;
}

static int oem_ec_read_ram(uint8_t page, uint8_t offset, uint8_t *data)
{
    unsigned char WEC, REC;
    switch(page)
    {
        case 0:
        {
            WEC = 0x96;
            REC = 0x95;
            break;
        }
        
        case 1:
        {
            WEC = 0x98;
            REC = 0x97;
            break;
        }
        
        default:
        {
            WEC = 0x81;
            REC = 0x80;
            break;
        }
    }    
    if (wait_ibf() < 0)
        return -1;
    outb(REC, EC_CMD_PORT);

    if (wait_ibf() < 0)
        return -1;
    outb(offset, EC_DATA_PORT);

    if (wait_obf() < 0)
        return -1;
    *data = inb(EC_DATA_PORT);

    return 0;
}

static int oem_ec_write_ram(uint8_t page, uint8_t offset, uint8_t data)
{
    unsigned char WEC, REC;
    switch(page)
    {
        case 0:
        {
            WEC = 0x96;
            REC = 0x95;
            break;
        }
        
        case 1:
        {
            WEC = 0x98;
            REC = 0x97;
            break;
        }
        
        default:
        {
            WEC = 0x81;
            REC = 0x80;
            break;
        }
    }
    if (wait_ibf() < 0)
        return -1;
    outb(WEC, EC_CMD_PORT);

    if (wait_ibf() < 0)
        return -1;
    outb(offset, EC_DATA_PORT);

    if (wait_ibf() < 0)
        return -1;
    outb(data, EC_DATA_PORT);

    return 0;
}



static ssize_t voltage_vbat_show(struct kobject *kobj, struct kobj_attribute *attr,
                         char *buf)
{
	int vlotage = 0;
    uint8_t raw;
	raw = hwm_read_reg_retry(IT8786_HWM_BASE_DEFAULT, 0x28);

	vlotage = vin_raw_to_volt(raw, 10, 10);

	return sprintf(buf, "%d\n", vlotage);
}

static ssize_t voltage_vbat_store(struct kobject *kobj, struct kobj_attribute *attr,
                                 const char *buf, size_t count)
{
    return -EINVAL;
}


static struct kobj_attribute voltage_vbat =
    __ATTR(voltage_vbat, 0644, voltage_vbat_show, voltage_vbat_store);

static struct attribute *vbat_attrs[] = {
    &voltage_vbat.attr,
    NULL,
};

static struct attribute_group vbat_attr_group = {
    .attrs = vbat_attrs,
};

int vbat_init(void)
{
    int ret = 0;

    ret = sysfs_create_group(hwmon_kobj, &vbat_attr_group);

    return ret;
}

void vbat_exit(void)
{
    sysfs_remove_group(hwmon_kobj, &vbat_attr_group);
}