#include <linux/init.h>
#include <linux/module.h>
#include <linux/kthread.h>
#include <linux/delay.h>
#include <linux/gpio.h>

MODULE_LICENSE("GPL");

/* GPIO */

#define A1  17 // 0
#define A2  18 // 1
#define A3  27 // 2
#define OE  22 // 3
#define LE  23 // 4
#define SDI 24 // 5
#define CLK 25 // 6

#define LINES 8
#define PER_LINE 12

static u8 pix_screen[LINES][PER_LINE] = {
    {
        0b00000000,0b00000000,0b00000000,0b00000000,
        0b00000000,0b00000000,0b00000000,0b00000000,
        0b00000000,0b00000000,0b00000000,0b00000000,
    },
    {
        0b00000000,0b00000000,0b00000000,0b00000000,
        0b00000000,0b00000000,0b00000000,0b00000000,
        0b00000000,0b00000000,0b00000000,0b00000000,
    },
    {
        0b00000000,0b00000000,0b00000000,0b00000000,
        0b00000000,0b00000000,0b00000000,0b00000000,
        0b00000000,0b00000000,0b00000000,0b00000000,
    },
    {
        0b00000000,0b00000000,0b00000000,0b00000000,
        0b00000000,0b00000000,0b00000000,0b00000000,
        0b00000000,0b00000000,0b00000000,0b00000000,
    },
    {
        0b00000000,0b00000000,0b00000000,0b00000000,
        0b00000000,0b00000000,0b00000000,0b00000000,
        0b00000000,0b00000000,0b00000000,0b00000000,
    },
    {
        0b00000000,0b00000000,0b00000000,0b00000000,
        0b00000000,0b00000000,0b00000000,0b00000000,
        0b00000000,0b00000000,0b00000000,0b00000000,
    },
    {
        0b00000000,0b00000000,0b00000000,0b00000000,
        0b00000000,0b00000000,0b00000000,0b00000000,
        0b00000000,0b00000000,0b00000000,0b00000000,
    },
    {
        0b00000000,0b00000000,0b00000000,0b00000000,
        0b00000000,0b00000000,0b00000000,0b00000000,
        0b00000000,0b00000000,0b00000000,0b00000000,
    },
};

void pix_line(u8 row){
    gpio_set_value(A1, !(row & 0b00000001));
    gpio_set_value(A2, !(row & 0b00000010));
    gpio_set_value(A3, !(row & 0b00000100));
}

void pix_dot(int x, int y, int r, int g, int b) {
    uint8_t l,p,t;

    if(y % 2){
        x = (x + 16);
    }
    y = (y / 2) - ((y / 2) % 1);

    l = x / 8;
    p = 7 - x % 8;
    t = pix_screen[y][l];

    //printf("line:%i, l:%i, p:%i, t:%i\n", y,l,p,t);

    if(r) {
        t |= 1 << p;
    }else{
        t &= ~(1 << p);
    }
    pix_screen[y][l] = t;

    l = x / 8 + 4;
    p = 7 - x % 8;
    t = pix_screen[y][l];
    if(g) {
        t |= 1 << p;
    }else{
        t &= ~(1 << p);
    }
    pix_screen[y][l] = t;

    l = x / 8 + 8;
    p = 7 - x % 8;
    t = pix_screen[y][l];
    if(b) {
        t |= 1 << p;
    }else{
        t &= ~(1 << p);
    }
    pix_screen[y][l] = t;
}

void pix_gpio_init(void){
    printk(KERN_INFO "PIX: starting gpio...");
    gpio_request(A1, "A1");
    gpio_request(A2, "A2");
    gpio_request(A3, "A3");

    gpio_request(OE, "OE");
    gpio_request(LE, "LE");
    gpio_request(SDI, "SDI");
    gpio_request(CLK, "CLK");

    gpio_direction_output(A1, 0);
    gpio_direction_output(A2, 0);
    gpio_direction_output(A3, 0);

    gpio_direction_output(OE, 1);
    gpio_direction_output(LE, 0);
    gpio_direction_output(SDI, 0);
    gpio_direction_output(CLK, 0);
    printk(KERN_INFO "PIX: starting gpio done.");
}

void pix_gpio_exit(void){
    printk(KERN_INFO "PIX: stopping gpio...");
    gpio_free(A1);
    gpio_free(A2);
    gpio_free(A3);

    gpio_free(OE);
    gpio_free(LE);
    gpio_free(SDI);
    gpio_free(CLK);
    printk(KERN_INFO "PIX: stopping gpio done.");
}



/* SYSFS */

static struct kobject *pix_kobject;

static ssize_t set_pix(struct kobject *kobj, struct kobj_attribute *attr, const char *buff, size_t count) {
    u8 x = 0;
    u8 y = 0;
    u8 r = 0;
    u8 g = 0;
    u8 b = 0;
    sscanf(buff, "%hhd %hhd %hhd %hhd %hhd", &x, &y, &r, &g, &b);

    pix_dot(x,y,r,g,b);
    // printk(KERN_INFO "PIX: %d %d %d %d %d", x,y,r,g,b);

    return count;
}

static struct kobj_attribute pix_attribute =__ATTR(dot, (S_IWUSR | S_IRUGO), NULL, set_pix);

void pix_sysfs_init(void){
    printk(KERN_INFO "PIX: starting sysfs...");
    pix_kobject = kobject_create_and_add("pix", NULL);
    if (sysfs_create_file(pix_kobject, &pix_attribute.attr)) {
        pr_debug("failed to create pix sysfs!\n");
    }
    printk(KERN_INFO "PIX: starting sysfs done.");
}

void pix_sysfs_exit(void){
    printk(KERN_INFO "PIX: stopping sysfs...");
    kobject_put(pix_kobject);
    printk(KERN_INFO "PIX: stopping sysfs done.");
}


/* THREAD */

#define THREAD_PRIORITY 45
#define THREAD_NAME "pix"

struct task_struct *task;

int pix_thread(void *data){
    u8 line, pos, bit;
    struct task_struct *TSK;
    struct sched_param PARAM = { .sched_priority = MAX_RT_PRIO - 50 };
    //struct sched_param PARAM = { .sched_priority = DEFAULT_PRIO };
    TSK = current;

    PARAM.sched_priority = THREAD_PRIORITY;
    sched_setscheduler(TSK, SCHED_FIFO, &PARAM);

    while(1) {
        for(line = 0; line < LINES; line++) {
            pix_line(line);
            for(pos = 0; pos < PER_LINE; pos++) {
                for (bit = 0; bit < 8; bit++)  {
                    gpio_set_value(SDI, !!(pix_screen[line][pos] & (1 << (7 - bit))));
                    gpio_set_value(CLK, 1);
                    gpio_set_value(CLK, 0);
                }
            }
            gpio_set_value(LE, 1);
            gpio_set_value(LE, 0);
            gpio_set_value(OE, 0);
            usleep_range(2000, 2000);
            gpio_set_value(OE, 1);
        }
        if (kthread_should_stop()) break;
    }
    return 0;
}

void pix_thread_init(void){
    printk(KERN_INFO "PIX: starting thread...");
    task = kthread_run(pix_thread, NULL, THREAD_NAME);
    printk(KERN_INFO "PIX: starting thread done.");
}

void pix_thread_exit(void){
    printk(KERN_INFO "PIX: stopping thread...");
    kthread_stop(task);
    printk(KERN_INFO "PIX: stopping thread done.");
}

/* MODULE */

static int __init pix_init(void){
    printk(KERN_INFO "PIX: staring...");
    pix_gpio_init();
    pix_thread_init();
    pix_sysfs_init();
    printk(KERN_INFO "PIX: staring done.");
    return 0;
}

static void __exit pix_exit(void){
    printk(KERN_INFO "PIX: stopping...");
    pix_sysfs_exit();
    pix_thread_exit();
    pix_gpio_exit();
    printk(KERN_INFO "PIX: stopping done.");
}

module_init(pix_init);
module_exit(pix_exit);