/*
 * usb/usb.c -- USB 2.0 implementation
 *
 * Copyright (C) 2016-2017 Tomasz Kramkowski <tk@the-tk.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#include <cm4.h>
#include <reg/gpio.h>
#include <reg/sim.h>
#include <reg/usbotg.h>
#include <stddef.h>

#include "../uart/uart.h"
#include "usb.h"
#include "bdt.h"
#include "endpt0.h"
#include "endpt1.h"

#define USBFRAC_VAL 1 /* 72 MHz * 2 = 144 MHz (Top of Fraction) */
#define USBDIV_VAL 2 /* 144 MHz / 3 = 48 MHz (Bottom of Fraction) */

__attribute__  ((aligned(512)))
volatile struct usb0_bd usb_bdt[2][2][2];

/* usb_setup: Setup function for USB subsystem */
void usb_setup(void)
{
	/* Clock Setup */
	SET_BIT(SIM_SOPT2, SOPT2_USBSRC);
	SET_MASKED(SIM_CLKDIV2, CLKDIV2_USBDIV_M | BV(CLKDIV2_USBFRAC),
		   USBDIV_VAL << CLKDIV2_USBDIV | USBFRAC_VAL << CLKDIV2_USBFRAC);
	SET_BIT(SIM_SCGC4, SCGC4_USBOTG);

	/* Reset USB and wait more than 2 USB clock cycles */
	SET_BIT(USB0_USBTRC0, USBTRC0_USBRESET);
	for (int i = 0; i < 5; i++)
		;

	/* 512 bit aligned BDT address */
	USB0_BDTPAGE1 = (uintptr_t)usb_bdt >> 8 & 0xff;
	USB0_BDTPAGE2 = (uintptr_t)usb_bdt >> 16 & 0xff;
	USB0_BDTPAGE3 = (uintptr_t)usb_bdt >> 24 & 0xff;

	/* Initial Configuration */
	SET_MASKED(USB0_USBCTRL, BV(USBCTRL_SUSP) | BV(USBCTRL_PDE), 0);
	SET_BIT(USB0_CONTROL, CONTROL_DPPULLUPNONOTG);
	USB0_INTEN = BV(INTEN_STALLEN) | BV(INTEN_ERROREN) | BV(INTEN_USBRSTEN);

	/* NVIC Enable interrupt */
	ISR_CLRPEND(73);
	ISR_SETENA(73);
	INTPRI(73) = 0x00;

	/* Enable USB */
	USB0_CTL = BV(CTL_USBENSOFEN);
}

/* i_usbrst: Handler for USBRST USB interrupt */
static void i_usbrst(void)
{
	SET_BIT(USB0_CTL, CTL_ODDRST);

	usb_endpt0_enable();
	usb_endpt1_disable();

	USB0_ADDR = 0;

	SET_BIT(USB0_INTEN, INTEN_TOKDNEEN);
}

/* i_tokdne: Handler for TOKDNE USB interrupt */
static void i_tokdne(void)
{
	uint8_t stat = USB0_STAT;

	switch (GET_BITS(stat, STAT_ENDP)) {
	case 0: usb_endpt0_token(stat); break;
	case 1: usb_endpt1_token(stat); break;
	}
}

/* usb_isr: interrupt service routine for the USB FS SIE */
void usb_isr(void)
{
	uint8_t stat = USB0_ISTAT;

	if (GET_BIT(stat, ISTAT_STALL)) {
		uart_puts("INT: stall");
		USB0_ISTAT = BV(ISTAT_STALL);
	}
	if (GET_BIT(stat, ISTAT_TOKDNE)) {
		i_tokdne();
		USB0_ISTAT = BV(ISTAT_TOKDNE);
	}
	if (GET_BIT(stat, ISTAT_ERROR)) {
		uart_printf("INT: error (0x%x)\n", (unsigned)USB0_ERRSTAT);
		USB0_ERRSTAT = USB0_ERRSTAT;
		USB0_ISTAT = BV(ISTAT_ERROR);
	}
	if (GET_BIT(stat, ISTAT_USBRST)) {
		i_usbrst();
		USB0_ISTAT = BV(ISTAT_USBRST);
	}
}