/**
 * @brief AHCI Block Device Driver
 * @file modules/ahci.c
 * @package x86_64
 *
 * @warning This is a stub driver.
 *
 * @copyright
 * This file is part of ToaruOS and is released under the terms
 * of the NCSA / University of Illinois License - see LICENSE.md
 * Copyright (C) 2021 K. Lange
 */
#include <kernel/syscall.h>
#include <kernel/module.h>
#include <kernel/printf.h>
#include <kernel/pci.h>
#include <kernel/vfs.h>
#include <kernel/mmu.h>

static uint32_t mmio_read4(uintptr_t mmiobase, intptr_t offset) {
	volatile uint32_t * data = (volatile uint32_t *)(mmiobase + offset);
	return *data;
}

static void mmio_write4(uintptr_t mmiobase, intptr_t offset, uint32_t value) {
	volatile uint32_t * data = (volatile uint32_t *)(mmiobase + offset);
	*data = value;
}

static char * ahci_device_name(uint32_t pcidev, int port) {
	static char buf[20];
	snprintf(buf,19,"ahcip%ds%dp%d",
			(int)pci_extract_bus(pcidev),
			(int)pci_extract_slot(pcidev),
			port);
	return buf;
}

#define AHCI_PXCMD_ST    (1 << 0UL)
#define AHCI_PXCMD_SUD   (1 << 1UL)
#define AHCI_PXCMD_POD   (1 << 2UL)
#define AHCI_PXCMD_CLO   (1 << 3UL)
#define AHCI_PXCMD_FRE   (1 << 4UL)
#define AHCI_PXCMD_MPSS  (1 << 13UL)
#define AHCI_PXCMD_FR    (1 << 14UL)
#define AHCI_PXCMD_CR    (1 << 15UL)

#define DPRINT(fmt,...) fprintf(stderr, "%s: " fmt, ahci_device_name(pcidev,port), ##__VA_ARGS__)
static void ahci_setup_atapi(fs_node_t * stderr, uint32_t pcidev, uintptr_t mmio_addr, int port) {
	intptr_t offset = 0x100 + port * 0x80;
	DPRINT("setting up ATAPI device\n");
	uint32_t PxCMD = mmio_read4(mmio_addr, offset + 0x18);
	DPRINT("device cmd: %#x\n", PxCMD);
	if (PxCMD & AHCI_PXCMD_ST)  DPRINT("  started (not idle!)\n");
	if (PxCMD & AHCI_PXCMD_FRE) DPRINT("  FIS receive enable (not idle!)\n");
	if (PxCMD & AHCI_PXCMD_FR)  DPRINT("  FIS receive running (not idle!)\n");
	if (PxCMD & AHCI_PXCMD_CR)  DPRINT("  command list running (not idle!)\n");

	if (PxCMD & (AHCI_PXCMD_ST | AHCI_PXCMD_FRE | AHCI_PXCMD_FR | AHCI_PXCMD_CR)) {
		DPRINT("Not idle, setting to idle state...\n");
		PxCMD &= ~(AHCI_PXCMD_ST);
		mmio_write4(mmio_addr, offset + 0x18, PxCMD);
		DPRINT("Waiting for device...\n");
		while (mmio_read4(mmio_addr, offset + 0x18) & AHCI_PXCMD_CR);
		DPRINT("Device is stopped.\n");
	}
}

static void find_ahci(uint32_t device, uint16_t vendorid, uint16_t deviceid, void * extra) {
	if (pci_find_type(device) != 0x0106) return; /* Mass Storage, SATA controller */
	if (pci_read_field(device, PCI_PROG_IF, 1) != 0x01) return; /* AHCI */
	fs_node_t * stderr = extra;

	fprintf(stderr, "ahci: located device at %#x\n", device);

	uint16_t command_reg = pci_read_field(device, PCI_COMMAND, 2);
	command_reg |= (1 << 2);
	command_reg |= (1 << 1);
	command_reg ^= (1 << 10);
	pci_write_field(device, PCI_COMMAND, 2, command_reg);

	fprintf(stderr, "ahci: examining PCI config space...\n");
	fprintf(stderr, "ahci: interrupt line = %d\n", pci_get_interrupt(device));
	fprintf(stderr, "ahci: BAR5 = %#x\n", pci_read_field(device, PCI_BAR5, 4));

	uintptr_t mmio_addr = (uintptr_t)mmu_map_mmio_region(pci_read_field(device, PCI_BAR5, 4) & 0xFFFFFFF0, 0x2000); /* I have no idea how much space this needs */
	fprintf(stderr, "ahci: mapping mmio to %#zx\n", mmio_addr);

	uint32_t enabledPorts = mmio_read4(mmio_addr, 0x0C);
	fprintf(stderr, "ahci: implemented ports = %#x\n", enabledPorts);

	uint32_t ahciVersion = mmio_read4(mmio_addr, 0x10);
	fprintf(stderr, "ahci: version %d.%d%d\n",
		(ahciVersion >> 16) & 0xFFF,
		(ahciVersion >> 8) & 0xFF,
		(ahciVersion) & 0xFF);

	fprintf(stderr, "ahci: Telling host controller we are aware of it.\n");
	mmio_write4(mmio_addr, 0x04, mmio_read4(mmio_addr, 0x04) | (1 << 31UL));

	int offset = 0x100;
	for (int port = 0; port < 32; ++port) {
		if (enabledPorts & (1UL << port)) {
			/* Check status */
			uint32_t portSig    = mmio_read4(mmio_addr, offset + 0x24);
			uint32_t portStatus = mmio_read4(mmio_addr, offset + 0x28);
			fprintf(stderr, "ahci: port %d: status = %#x\n", port, portStatus);
			fprintf(stderr, "ahci: port %d: sig    = %#x\n", port, portSig);

			switch (portSig) {
				case 0xeb140101:
					fprintf(stderr, "ahci:           ATAPI (CD, DVD)\n");
					ahci_setup_atapi(stderr, device, mmio_addr, port);
					break;
				case 0x00000101:
					fprintf(stderr, "ahci:           hard disk\n");
					break;
				case 0xffff0101:
					fprintf(stderr, "ahci:           no device\n");
					break;
				default:
					fprintf(stderr, "ahci:           unsupported/unknown\n");
					break;
			}

		}
		offset += 0x80;
	}


	
}

static int init(int argc, char * argv[]) {
	fs_node_t * node = FD_ENTRY(1); /* Get the stdout for the process that loaded the module */
	pci_scan(find_ahci, -1, node);
	return 0;
}

static int fini(void) {
	return 0;
}

struct Module metadata = {
	.name = "ahci",
	.init = init,
	.fini = fini,
};