#include <socks/printk.h>
#include <socks/pci.h>
#include <socks/device.h>
#include <socks/kext.h>
#include <socks/machine/init.h>
#include <socks/libc/stdio.h>

#define VBE_DISPI_INDEX_ID 0x00u
#define VBE_DISPI_INDEX_XRES 0x01u
#define VBE_DISPI_INDEX_YRES 0x02u
#define VBE_DISPI_INDEX_BPP 0x03u
#define VBE_DISPI_INDEX_ENABLE 0x04u
#define VBE_DISPI_INDEX_BANK 0x05u
#define VBE_DISPI_INDEX_VIRT_WIDTH 0x06u
#define VBE_DISPI_INDEX_VIRT_HEIGHT 0x07u
#define VBE_DISPI_INDEX_X_OFFSET 0x08u
#define VBE_DISPI_INDEX_Y_OFFSET 0x09u

#define VBE_DISPI_LFB_ENABLED 0x40

static struct pci_driver *qemufb_driver = NULL;

static struct pci_device_id qemufb_device_ids[] = {
	PCI_DEVICE_ID(0x1234, 0x1111),
	PCI_DEVICE_ID_INVALID,
};

static inline uint16_t dispi_mmio_offset(int index)
{
	return (0x500 + (index << 1)) >> 1;
}

static kern_status_t qemufb_set_varinfo(struct device *dev, const struct framebuffer_varinfo *varinfo)
{
	struct framebuffer_device *fbdev = FRAMEBUFFER_DEVICE(dev);
	uint32_t mmio_base = pci_device_read_field(dev, PCI_REG_BAR2, 4);
	uint16_t *mmio = vm_phys_to_virt(mmio_base);

	mmio[dispi_mmio_offset(VBE_DISPI_INDEX_ENABLE)] = 0;
	mmio[dispi_mmio_offset(VBE_DISPI_INDEX_XRES)] = varinfo->fb_xres;
	mmio[dispi_mmio_offset(VBE_DISPI_INDEX_YRES)] = varinfo->fb_yres;
	mmio[dispi_mmio_offset(VBE_DISPI_INDEX_BPP)] = varinfo->fb_bpp;
	mmio[dispi_mmio_offset(VBE_DISPI_INDEX_ENABLE)] = 1 | VBE_DISPI_LFB_ENABLED;

	if (mmio[dispi_mmio_offset(VBE_DISPI_INDEX_XRES)] != varinfo->fb_xres ||
	    mmio[dispi_mmio_offset(VBE_DISPI_INDEX_YRES)] != varinfo->fb_yres ||
	    mmio[dispi_mmio_offset(VBE_DISPI_INDEX_BPP)] != varinfo->fb_bpp) {
		return KERN_UNSUPPORTED;
	}

	fbdev->fb_fixedinfo.fb_baseptr = pci_device_read_field(dev, PCI_REG_BAR0, 4) & ~(VM_PAGE_SIZE - 1);

	return KERN_OK;
}

static struct framebuffer_device_ops qemufb_ops = {
	.set_varinfo = qemufb_set_varinfo,
};

static kern_status_t qemufb_probe(struct pci_driver *driver, struct device *dev)
{
	struct framebuffer_device *fb = framebuffer_device_from_generic(dev);
	(void)fb;
	snprintf(dev->dev_name, sizeof dev->dev_name, "qemufb");

	fb->fb_ops = &qemufb_ops;

	uint32_t mmio_base = pci_device_read_field(dev, PCI_REG_BAR2, 4);
	uint16_t *mmio = vm_phys_to_virt(mmio_base);

	struct framebuffer_varinfo *varinfo = &fb->fb_varinfo;
	struct framebuffer_fixedinfo *fixedinfo = &fb->fb_fixedinfo;

	varinfo->fb_flags = FB_MODE_RGB;
	varinfo->fb_xres = mmio[dispi_mmio_offset(VBE_DISPI_INDEX_XRES)];
	varinfo->fb_yres = mmio[dispi_mmio_offset(VBE_DISPI_INDEX_YRES)];
	varinfo->fb_bpp = mmio[dispi_mmio_offset(VBE_DISPI_INDEX_BPP)];
	varinfo->fb_stride = varinfo->fb_bpp / 8;
	fixedinfo->fb_baseptr = pci_device_read_field(dev, PCI_REG_BAR0, 4) & (VM_PAGE_SIZE - 1);

	if (!varinfo->fb_xres) {
		/* no mode data. assume that we're in VGA text mode */
		varinfo->fb_xres = 640;
		varinfo->fb_yres = 400;
		varinfo->fb_bpp = 16;
		varinfo->fb_flags = FB_MODE_VGATEXT;
		varinfo->fb_xcells = 80;
		varinfo->fb_ycells = 25;
		varinfo->fb_stride = 80 * 25 * 2;
		fixedinfo->fb_baseptr = 0xb8000;
	}

	return device_register(dev, pci_driver_base(qemufb_driver), NULL);
}

static kern_status_t online(struct kext *self)
{
	printk("qemufb: registering PCI driver");
	qemufb_driver = pci_driver_create(self, "qemufb", qemufb_device_ids);
	if (!qemufb_driver) {
		return KERN_NO_MEMORY;
	}

	qemufb_driver->probe = qemufb_probe;

	pci_driver_register(qemufb_driver);
	return KERN_OK;
}

DEFINE_KEXT("net.doorstuck.socks.qemufb",
	    online, NULL,
	    PCI_SUBSYSTEM_KEXT_ID);