kolibrios-nvme-driver/drivers/nvme/nvme.asm

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;                                                                 ;;
;; Copyright (C) KolibriOS team 2004-2024. All rights reserved.    ;;
;; Distributed under terms of the GNU General Public License       ;;
;;                                                                 ;;
;;          GNU GENERAL PUBLIC LICENSE                             ;;
;;             Version 2, June 1991                                ;;
;;                                                                 ;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

format PE DLL native
entry START

API_VERSION     equ 0  ;debug
SRV_GETVERSION  equ 0
__DEBUG__ = 1
__DEBUG_LEVEL__ = 1
DRIVER_VERSION = 1
DBG_INFO = 1
NULLPTR = 0
FALSE = 0
TRUE = 1

; flags for alloc_dptr
PRP1_ENTRY_ALLOCATED = 1
PRP1_LIST_ALLOCATED = 2
PRP2_ENTRY_ALLOCATED = 4
PRP2_LIST_ALLOCATED = 8

section ".flat" code readable writable executable
include "../proc32.inc"
include "../struct.inc"
include "../macros.inc"
include "../fdo.inc"
include "../pci.inc"
include "../peimport.inc"
include "nvme.inc"
include "macros.inc"
include "lib.asm"

struct DISKMEDIAINFO
	flags 		dd ?
	sectorsize  	dd ?
	capacity 	dq ?
ends

proc START c, reason:dword

	cmp     [reason], DRV_ENTRY
	jne     .err

.entry:
	DEBUGF  DBG_INFO, "Detecting NVMe hardware...\n"
	call    detect_nvme
	test 	eax, eax
	jz      .err
	mov 	eax, dword [p_nvme_devices]
	test 	eax, eax
	jz 	.err
	xor 	ecx, ecx

.loop:
	mov 	ebx, dword [p_nvme_devices]
	stdcall device_is_compat, ebx
	test 	eax, eax
	jz 	@f
	stdcall nvme_init, ebx
	test 	eax, eax
	jz 	.err

;@@:
	;inc 	ecx
	;cmp 	ecx, dword [pcidevs_len]
	;jne 	.loop
	stdcall add_nvme_disk, [p_nvme_devices]
	test 	eax, eax
	jz 	.err
	invoke  RegService, my_service, service_proc
	ret

.err:
	call    nvme_cleanup
      	xor     eax, eax
      	ret

endp

proc service_proc stdcall, ioctl:dword

      	mov     esi, [ioctl]
      	mov     eax, [esi + IOCTL.io_code]
      	cmp     eax, SRV_GETVERSION
      	jne     .ret

      	mov     eax, [esi + IOCTL.output]
      	cmp     [esi + IOCTL.out_size], 4
      	jne     .ret
      	mov     dword [eax], API_VERSION
      	xor     eax, eax
      	ret

.ret:
	or      eax, -1
	ret

endp

proc add_nvme_disk stdcall, pci:dword

	push 	esi
	mov 	esi, [pci]
	push 	0 ; null terminator
	push 	dword [esi + pcidev.nsid]
	push 	"n"
	push 	dword [esi + pcidev.num]
	push 	"nvme"
	mov 	eax, esp
	invoke  DiskAdd, disk_functions, eax, [esi + pcidev.nsinfo], 0
	add 	esp, 20
	test 	eax, eax
	jz 	@f
	DEBUGF  DBG_INFO, "nvme%u: Successfully registered disk\n", [esi + pcidev.num]
	xor 	eax, eax
	inc 	eax
	pop 	esi
	ret

@@:
	DEBUGF  DBG_INFO, "nvme%u: Failed to register disk\n", [esi + pcidev.num]
	xor 	eax, eax
	pop 	esi
	ret

endp

proc nvme_query_media stdcall, userdata:dword, info:dword

	push 	esi edi
	mov 	esi, [userdata]
	mov 	edi, [info]
	mov 	dword [edi + DISKMEDIAINFO.flags], 0
	mov 	eax, dword [esi + NSINFO.lbads]
	mov 	dword [edi + DISKMEDIAINFO.sectorsize], eax
	mov 	eax, dword [esi + NSINFO.capacity]
	mov 	dword [edi + DISKMEDIAINFO.capacity], eax
	mov 	eax, dword [esi + NSINFO.capacity + 4]
	mov 	dword [edi + DISKMEDIAINFO.capacity + 4], eax
	xor 	eax, eax
	pop 	edi esi
	ret

endp

proc set_cdw0 stdcall, pci:dword, y:dword, opcode:byte

	stdcall get_new_cid, [pci], [y]
	shl 	eax, 16
	or 	al, [opcode]
	ret

endp

; See pages 161-205 of the NVMe 1.4 specification for reference
proc nvme_identify stdcall, pci:dword, nsid:dword, dptr:dword, cns:byte

	sub 	esp, sizeof.SQ_ENTRY
	; It's important to check if CNS is a valid value here. In revision 1.0
	; CNS is a 1 bit field and a two bit field in revision 1.1, using invalid
	; values results in undefined behavior (see page 162 of NVMe 1.4 spec)
	if __DEBUG__
		push 	esi
		mov 	esi, [pci]
		mov 	esi, dword [esi + pcidev.io_addr]
		mov 	eax, dword [esi + NVME_MMIO.VS]
		cmp 	eax, VS110
		jne 	@f
		cmp 	[cns], 11b
		jbe	.ok
		DEBUGF  DBG_INFO, "(NVMe) FATAL ERROR: INVALID CNS VALUE ON v1.1.0 CONTROLLERS\n"
		jmp 	.err
	
		@@:
		cmp 	eax, VS100
		jne 	.ok
		cmp 	[cns], 1b
		jbe 	.ok
		DEBUGF  DBG_INFO, "(NVMe) FATAL ERROR: INVALID CNS VALUE ON v1.0.0 CONTROLLERS\n"
		jmp 	.err

		.err:
		jmp 	@b
		
		.ok:
		pop 	esi
		
	end if

	stdcall memsetdz, esp, sizeof.SQ_ENTRY / 4

	mov     eax, [nsid]
	mov     dword [esp + SQ_ENTRY.nsid], eax
	mov     eax, [dptr]
	mov     dword [esp + SQ_ENTRY.dptr], eax
	stdcall set_cdw0, [pci], ADMIN_QUEUE, ADM_CMD_IDENTIFY
	mov 	dword [esp + SQ_ENTRY.cdw0], eax
	mov     al, [cns]
	mov     byte [esp + SQ_ENTRY.cdw10], al
	stdcall sqytdbl_write, [pci], ADMIN_QUEUE, esp

	add 	esp, sizeof.SQ_ENTRY
	ret

endp

; See pages 348-349 of the NVMe 1.4 specification for information on creating namespaces
proc create_namespace stdcall, pci:dword, cid:word
	
	push 	esi
	invoke  AllocPage
	test 	eax, eax
	jz 	.fail
	invoke  GetPhysAddr
	stdcall nvme_identify, [pci], 0xffffffff, eax, CNS_IDNS

.fail:
	pop 	esi
	ret

endp

; returns 1 if the given NSID is a an active NSID, returns
; 0 otherwise
proc is_active_namespace stdcall, pci:dword, nsid:dword
	
	push 	esi edi
	invoke  KernelAlloc, 0x1000
	test 	eax, eax
	jnz 	@f
	pop 	edi esi
	ret

@@:
	mov 	esi, eax
	invoke  GetPhysAddr
	stdcall nvme_identify, [pci], [nsid], eax, CNS_IDNS
	xor 	ecx, ecx

@@:
	mov 	eax, dword [esi + ecx * 4]
	test 	eax, eax
	jnz 	.is_active_nsid
	inc 	ecx
	cmp 	ecx, 0x1000 / 4
	jne 	@b
	
.not_active_nsid:
	invoke  KernelFree, esi
	pop 	edi esi
	xor 	eax, eax
	ret

.is_active_nsid:
	invoke  KernelFree, esi
	pop 	edi esi
	xor 	eax, eax
	inc 	eax
	ret

endp

; See page 248 of the NVMe 1.4 specification for reference
; Returns the number of namespaces that are active, note this
; doesn't mean if EAX = 5, then namespaces 1-5 will be active.
; This also sets [pci + pcidev.nn] and [pci + pcidev.nsids] 
; to appropriate values
proc determine_active_nsids stdcall, pci:dword

	push 	ebx esi
	mov 	esi, [pci]
	xor 	ebx, ebx
	xor 	ecx, ecx
	inc 	ecx

.loop:
	cmp 	ecx, dword [esi + pcidev.nn]
	ja 	.ret
	push 	ecx
	stdcall is_active_namespace, [pci], ecx
	pop 	ecx
	test 	eax, eax
	jz 	.not_active_namespace
	mov 	ebx, ecx
	jmp 	.ret

.not_active_namespace:
	inc 	ecx
	jmp 	.loop

.ret:
	pop 	edi esi
	mov 	eax, ebx
	ret

endp

; See page 101 of the NVMe 1.4 specification for reference
proc create_io_completion_queue stdcall, pci:dword, prp1:dword, qid:dword, ien:byte
	
	sub 	esp, sizeof.SQ_ENTRY
	stdcall memsetdz, esp, sizeof.SQ_ENTRY / 4
	stdcall set_cdw0, [pci], ADMIN_QUEUE, ADM_CMD_CRE_IO_COMPLETION_QUEUE
	mov 	dword [esp + SQ_ENTRY.cdw0], eax
	mov 	eax, [prp1]
	mov 	dword [esp + SQ_ENTRY.dptr], eax
	mov 	eax, sizeof.CQ_ENTRY shl 16 ; CDW10.QSIZE
	or 	eax, [qid] ; CDW10.QID
	mov 	dword [esp + SQ_ENTRY.cdw10], eax
	movzx 	eax, [ien] ; CDW11.IEN 
	or 	eax, 0x1 ; CDW11.PC
	; Don't set CDW11.IV since we're not using MSI-X or MSI vector
	mov 	dword [esp + SQ_ENTRY.cdw11], eax
	stdcall sqytdbl_write, [pci], ADMIN_QUEUE, esp
	add 	esp, sizeof.SQ_ENTRY
	ret

endp

; See page 103-104 of the NVMe 1.4 specification for reference
proc create_io_submission_queue stdcall, pci:dword, prp1:dword, qid:dword, cqid:word

	sub 	esp, sizeof.SQ_ENTRY
	stdcall memsetdz, esp, sizeof.SQ_ENTRY / 4
	stdcall set_cdw0, [pci], ADMIN_QUEUE, ADM_CMD_CRE_IO_SUBMISSION_QUEUE
	mov 	dword [esp + SQ_ENTRY.cdw0], eax
	mov 	eax, [prp1]
	mov 	dword [esp + SQ_ENTRY.dptr], eax
	mov 	eax, sizeof.SQ_ENTRY shl 16 ; CDW10.QSIZE
	or 	eax, [qid]
	mov 	dword [esp + SQ_ENTRY.cdw10], eax
	movzx 	eax, [cqid]
	shl 	eax, 16 ; CDW11.CQID
	or 	eax, 0x1 ; CDW11.PC (always set this to 1 as some devices may not support non-contiguous pages)
	; TODO: Set CDW10.QPRIO 
	mov 	dword [esp + SQ_ENTRY.cdw11], eax
	stdcall sqytdbl_write, [pci], ADMIN_QUEUE, esp
	add 	esp, sizeof.SQ_ENTRY
	ret

endp

; See page 95-96 of the NVMe 1.4 specification for reference
proc abort stdcall, pci:dword, cid:word, sqid:word

	sub 	esp, sizeof.SQ_ENTRY
	stdcall memsetdz, esp, sizeof.SQ_ENTRY / 4
	stdcall set_cdw0, [pci], ADMIN_QUEUE, ADM_CMD_ABORT
	mov 	dword [esp + SQ_ENTRY.cdw0], eax
	movzx 	eax, [cid]
	shl 	eax, 16
	or 	eax, word [sqid]
	mov 	dword [esp + SQ_ENTRY.cdw10], eax
	stdcall sqytdbl_write, [pci], ADMIN_QUEUE, esp
	add 	esp, sizeof.SQ_ENTRY
	ret

endp


; See page 205 of the NVMe 1.4 specification for reference
proc set_features stdcall, pci:dword, dptr:dword, fid:byte, cdw11:dword
	
	sub 	esp, sizeof.SQ_ENTRY
	stdcall memsetdz, esp, sizeof.SQ_ENTRY / 4
	stdcall set_cdw0, [pci], ADMIN_QUEUE, ADM_CMD_SET_FEATURES
	mov 	dword [esp + SQ_ENTRY.cdw0], eax
	mov 	eax, [dptr]
	mov 	dword [esp + SQ_ENTRY.dptr], eax
	movzx 	eax, [fid]
	;or 	eax, 1 shl 31 ; CDW10.SV
	mov 	dword [esp + SQ_ENTRY.cdw10], eax
	mov 	eax, [cdw11]
	mov 	dword [esp + SQ_ENTRY.cdw11], eax
	stdcall sqytdbl_write, [pci], ADMIN_QUEUE, esp
	add 	esp, sizeof.SQ_ENTRY
	ret

endp

; See page 105 of the NVMe 1.4 specification for reference
proc delete_io_completion_queue stdcall, pci:dword, qid:word

	sub 	esp, sizeof.SQ_ENTRY
	stdcall memsetdz, esp, sizeof.SQ_ENTRY / 4
	stdcall set_cdw0, [pci], ADMIN_QUEUE, ADM_CMD_DEL_IO_COMPLETION_QUEUE
	mov 	dword [esp + SQ_ENTRY.cdw0], eax
	mov 	ax, [qid]
	mov 	word [esp + SQ_ENTRY.cdw10], ax
	stdcall sqytdbl_write, [pci], ADMIN_QUEUE, esp
	add 	esp, sizeof.SQ_ENTRY
	ret

endp

; See page 114-116 of the NVMe 1.4 specification for reference
proc get_features stdcall, pci:dword, dptr:dword, sel:byte, fid:byte
	
	sub 	esp, sizeof.SQ_ENTRY
	stdcall memsetdz, esp, sizeof.SQ_ENTRY / 4
	stdcall set_cdw0, [pci], ADMIN_QUEUE, ADM_CMD_GET_FEATURES
	mov 	dword [esp + SQ_ENTRY.cdw0], eax
	movzx 	eax, [sel]
	and 	eax, 111b
	shl 	eax, 8 ; CDW10.SEL
	or 	eax, byte [fid] ; CDW10.FID
	mov 	dword [esp + SQ_ENTRY.cdw10], eax
	mov 	eax, [dptr]
	mov 	dword [esp + SQ_ENTRY.dptr], eax
	; TODO: Implement CDW14.UUID?
	stdcall sqytdbl_write, [pci], ADMIN_QUEUE, esp
	add 	esp, sizeof.SQ_ENTRY
	ret

endp

; See page 105-106 of the NVMe 1.4 specification for reference
proc delete_io_submission_queue stdcall, pci:dword, qid:word

	sub 	esp, sizeof.SQ_ENTRY
	stdcall memsetdz, esp, sizeof.SQ_ENTRY / 4
	stdcall set_cdw0, [pci], ADMIN_QUEUE, ADM_CMD_DEL_IO_SUBMISSION_QUEUE
	mov 	dword [esp + SQ_ENTRY.cdw0], eax
	mov 	ax, [qid]
	mov 	word [esp + SQ_ENTRY.cdw10], ax
	stdcall sqytdbl_write, [pci], ADMIN_QUEUE, esp
	add 	esp, sizeof.SQ_ENTRY
	ret

endp

; See page 117-118 of the NVMe 1.4 specification for reference
; INCOMPLETE
proc get_log_page stdcall, pci:dword, dptr:dword, lid:byte

	sub 	esp, sizeof.SQ_ENTRY
	stdcall memsetdz, esp, sizeof.SQ_ENTRY / 4
	stdcall set_cdw0, [pci], ADMIN_QUEUE, ADM_CMD_GET_LOG_PAGE
	mov 	dword [esp + SQ_ENTRY.cdw0], eax
	mov 	eax, [dptr]
	mov 	dword [esp + SQ_ENTRY.dptr], eax
	add 	esp, sizeof.SQ_ENTRY
	ret

endp

proc free_prp_list stdcall, prp_list_ptr:dword, nprps:dword, recursive:byte

	push 	edi
	mov 	edi, [prp_list_ptr]
	mov 	ecx, [nprps]
	cmp 	ecx, PAGE_SIZE / 8 - 1
	jbe 	@f
	mov 	eax, dword [edi + PAGE_SIZE - 8]
	sub 	ecx, PAGE_SIZE / 8 - 1
	stdcall free_prp_list, eax, ecx, TRUE

@@:
	cmp 	[recursive], 0
	jz 	@f
	invoke  FreePage, edi
	jmp 	.exit
	
@@:
	invoke  KernelFree, edi

.exit:
	xor 	eax, eax
	pop 	edi
	ret

endp

proc build_prp_list stdcall, nprps:dword

	push 	esi ebx edi
	xor 	edi, edi
	xor 	esi, esi
	mov 	ecx, [nprps]
	mov 	ebx, ecx
	shl 	ecx, 3
	invoke  KernelAlloc, ecx ; store pointers to the PRP entries here
	test 	eax, eax
	jz 	.err
	mov 	edi, eax
	mov 	ecx, ebx
	imul 	ecx, PAGE_SIZE
	invoke  KernelAlloc, ecx
	test 	eax, eax
	jz 	.err
	mov 	esi, eax
	xor 	ecx, ecx
	push 	esi

.loop:
	; check if we need to build another PRP list
	mov 	eax, ebx
	sub 	eax, PAGE_SIZE
	; is this the last entry in the list? If so, build yet another PRP list here
	cmp 	ecx, PAGE_SIZE / 8 - 1
	jne 	@f
	push 	ecx
	stdcall build_prp_list, eax, TRUE
	pop 	ecx
	test 	eax, eax
	jz 	.cleanup_prp_list
	invoke  GetPhysAddr
	mov 	dword [edi + ecx * 4], eax
	mov 	dword [edi + ecx * 4 + 4], 0
	jmp 	.success

@@:
	mov 	eax, esi
	push 	ecx
	invoke  GetPhysAddr
	pop 	ecx
	mov 	dword [edi + ecx * 4], eax
	mov 	dword [edi + ecx * 4 + 4], 0
	add 	esi, PAGE_SIZE
	inc 	ecx
	cmp 	ecx, ebx
	jb 	.loop

.success:
	mov 	eax, edi
	pop 	esi
	pop 	edi ebx esi
	ret

.cleanup_prp_list:
	pop 	esi
	invoke  KernelFree, esi

.err:
	test 	edi, edi
	jz 	@f
	invoke  KernelFree, edi

@@:
	pop 	edi ebx esi
	xor 	eax, eax
	ret
	
endp

proc alloc_dptr stdcall, ns:dword, prps_ptr:dword, start_sector:qword, numsectors:dword

	push 	esi edi
	mov 	esi, [ns]
	mov 	edi, [prps_ptr]
	mov 	dword [esi], 0
	mov 	dword [esi + 4], 0
	invoke  KernelAlloc, PAGE_SIZE
	test 	eax, eax
	jz 	.err
	mov 	dword [edi], eax

	; is the number of sectors equal to two memory pages in size?
	mov 	eax, dword [esi + NSINFO.pg_sectors]
	shl 	eax, 1
	cmp 	eax, [numsectors]
	jne 	@f
	
	; allocate a single PRP entry for PRP2
	invoke  KernelAlloc, PAGE_SIZE
	test 	eax, eax
	jz 	.err
	mov 	dword [edi + 4], eax
	jmp 	.success

@@:
	; allocate PRP list for PRP2
	shr 	eax, 1
	mov 	ecx, [numsectors]
	xchg 	eax, ecx
	xor 	edx, edx
	div 	ecx
	stdcall build_prp_list, eax
	test 	eax, eax
	jz 	.free_prp_list
	mov 	dword [edi + 4], eax
	jmp 	.success
	
.free_prp_list:
	stdcall free_prp_list, edi, eax, FALSE

.err:
	mov 	eax, dword [edi]
	test 	eax, eax
	jz 	@f
	invoke  KernelFree, eax

@@:
	xor 	eax, eax
	pop 	edi esi
	ret

.success:
	xor 	eax, eax
	inc 	eax
	pop 	edi esi
	ret
	
endp

proc write_prp_buf stdcall, ns:dword, prp:dword, dst:dword, numsectors_ptr:dword

	push 	esi edi ebx
	mov 	esi, [prp]
	test 	esi, esi
	jz 	.err
	invoke  KernelAlloc, PAGE_SIZE
	test 	eax, eax
	jz 	.err
	mov 	esi, eax
	mov 	edi, [prp]
	invoke  MapPage, edi, esi, PG_SW+PG_NOCACHE
	mov 	esi, edi
	mov 	edi, [dst]
	; determine if the number of sectors crosses a page boundary
	mov 	eax, [ns]
	mov 	ebx, [numsectors_ptr]
	mov 	ecx, dword [eax + NSINFO.lbads]
	mov 	eax, dword [eax + NSINFO.pg_sectors]
	cmp 	eax, dword [ebx]
	jae 	@f
	mov 	eax, dword [ebx]
	imul 	ecx, eax
	shr 	ecx, 2
	sub 	dword [ebx], eax

@@:
	mov 	ecx, PAGE_SIZE / 4
	sub 	dword [ebx], eax

.copy:
	rep 	movsd
	sub 	esi, ecx
	invoke  KernelFree, esi
	invoke  FreePage, [prp]
	pop 	ebx edi esi
	xor 	eax, eax
	inc 	eax
	ret

.err:
	mov 	esi, [prp]
	test 	esi, esi
	jz 	@f
	invoke  FreePage, esi

@@:
	pop 	ebx edi esi
	xor 	eax, eax
	ret

endp

; note that prp_list is required to be a physical address
proc write_prp_list_buf stdcall, prp_list:dword, dst:dword, nprps:dword

	push 	esi edi
	mov 	esi, [prp_list]
	invoke  KernelAlloc, 0x1000
	test 	eax, eax
	jz 	.err
	mov 	edi, eax
	push 	edi
	invoke  MapPage, edi, esi, PG_SW+PG_NOCACHE
	mov 	esi, edi
	mov 	edi, [dst]
	mov 	ecx, [nprps]
	cmp 	ecx, PAGE_SIZE
	jae 	@f
	shl 	ecx, (12 + NVM_MPS) - 2
	rep 	stosd
	pop 	edi
	invoke  KernelFree, edi
	pop 	edi esi
	xor 	eax, eax
	inc 	eax
	ret

; more than or equal to 4096 PRP entries
@@:
	; WIP: Work on this later
	if 0
	mov 	ecx, PAGE_SIZE * PAGE_SIZE / 4 - 3
	rep 	stosd
	stdcall write_prp_list_buf, [prp_list], edi, ecx
	mov 	esi, eax
	pop 	edi
	invoke  KernelFree, edi
	mov 	eax, esi
	end if

.err:
	pop 	edi esi
	ret

endp


nvme_read:
	mov 	edx, NVM_CMD_READ
	jmp 	nvme_readwrite

nvme_write:
	mov 	edx, NVM_CMD_WRITE

proc nvme_readwrite stdcall, ns:dword, dst:dword, start_sector:qword, numsectors_ptr:dword

	push 	ebx esi edi
	sub 	esp, 16
	mov 	ebx, [numsectors_ptr]
	mov 	ebx, [ebx]
	mov 	dword [esp + 8], edx ; command type (read or write)
	mov 	dword [esp + 12], ebx ; save original numsectors value

	; Note that [esp] will contain the value of PRP1 and [esp + 4] will
	; contain the value of PRP2 (after this call, if it completes successfully)
	stdcall alloc_dptr, [ns], esp, dword [start_sector], dword [start_sector + 4], ebx
	test 	eax, eax
	jz 	.end
	invoke  GetPhysAddr
	mov 	esi, [ns]
	stdcall nvme_io_rw, [esi + NSINFO.pci], \
	                        1,  \
	                        [esi + NSINFO.nsid], \
	                        dword [esp], \
				dword [esp + 4], \
	                        dword [start_sector], \
	                        dword [start_sector + 4], \
	                        ebx, \
	                        dword [esp + 8]

	; assume command completes successfully for now

	; Write PRP1
	stdcall write_prp_buf, [ns], dword [esp], [dst], [numsectors_ptr]
	test 	eax, eax
	jz 	.end

	; check if PRP2 is needed at all
	mov 	ecx, dword [esi + NSINFO.pg_sectors]
	cmp 	ecx, ebx
	jbe 	.end

	; check if PRP2 should be a PRP list or a regular entry
	shl 	ecx, 1
	cmp 	ecx, ebx
	ja 	.is_prp_list

	; PRP2 is a PRP entry
	mov 	edi, [dst]
	mov 	eax, dword [esp + 12]
	mov 	edx, [ns]
	imul 	eax, dword [edx + NSINFO.lbads]
	mov 	ebx, [numsectors_ptr]
	sub 	eax, dword [ebx]
	add 	edi, eax
	stdcall write_prp_buf, [ns], dword [esp + 4], edi, [numsectors_ptr]
	jmp 	.end

.is_prp_list:
	mov 	esi, [ns]
	mov 	eax, ebx
	xor 	edx, edx
	mov 	ecx, dword [esi + NSINFO.lbads]
	div 	ecx
	mov 	ebx, eax
	stdcall write_prp_list_buf, dword [esp + 4], [dst], ebx
	stdcall free_prp_list, dword [esp + 4], ebx, FALSE

.end:
	add 	esp, 16
	pop 	edi esi ebx
	ret

endp

; See page 258-261 (read) and 269-271 (write) of the NVMe 1.4 specification for reference
proc nvme_io_rw stdcall, pci:dword, qid:word, nsid:dword, prps:qword, slba_lo:dword, slba_hi:dword, nlb:word, opcode:dword
	
	; TODO: Use IDENTC.NOIOB to construct read/write commands that don't
	; cross the I/O boundary to achieve optimal performance
	; 
	; TODO: Read AWUN/NAWUN
	sub 	esp, sizeof.SQ_ENTRY
	stdcall memsetdz, esp, sizeof.SQ_ENTRY / 4
	movzx 	ecx, [qid]
	stdcall set_cdw0, [pci], ecx, [opcode]
	mov 	dword [esp + SQ_ENTRY.cdw0], eax ; CDW0
	mov 	eax, dword [prps]
	mov 	dword [esp + SQ_ENTRY.dptr], eax
	mov 	eax, dword [prps + 4]
	mov 	dword [esp + SQ_ENTRY.dptr + 8], eax
	mov 	eax, [nsid]
	mov 	dword [esp + SQ_ENTRY.nsid], eax
	mov 	eax, [slba_lo]
	mov 	dword [esp + SQ_ENTRY.cdw10], eax
	mov 	eax, [slba_hi]
	mov 	dword [esp + SQ_ENTRY.cdw11], eax
	movzx 	eax, [nlb]
	mov 	word [esp + SQ_ENTRY.cdw12], ax
	movzx 	ecx, [qid]
	stdcall sqytdbl_write, [pci], ecx, esp
	add 	esp, sizeof.SQ_ENTRY
	ret
	
endp

proc detect_nvme

      	invoke  GetPCIList
	mov 	edx, eax

.check_dev:
	mov 	ebx, dword [eax + PCIDEV.class]
	and	ebx, 0x00ffff00 ; retrieve class/subclass code only
	cmp 	ebx, 0x00010800 ; Mass Storage Controller - Non-Volatile Memory Controller
	je	.found_dev

.next_dev:
	mov	eax, dword [eax + PCIDEV.fd]
	cmp	eax, edx
	jne 	.check_dev
	jmp 	.exit_success

.found_dev:
	push    edx eax
	PDEBUGF DBG_INFO, "PCI(%u.%u.%u): Detected NVMe device...\n", byte [eax + PCIDEV.bus], byte [eax + PCIDEV.devfn]
	cmp 	dword [pcidevs_len], TOTAL_PCIDEVS
	jne 	@f
	pop 	eax edx
	jmp 	.exit_success

@@:
	inc 	dword [pcidevs_len]
	mov     ebx, dword [p_nvme_devices]
	test    ebx, ebx
	jnz	@f
	invoke  KernelAlloc, sizeof.pcidev
	test 	eax, eax
	jz 	.err_no_mem
	mov     dword [p_nvme_devices], eax 
	DEBUGF  DBG_INFO, "(NVMe) Allocated pcidev struct at 0x%x\n", [p_nvme_devices]

@@:
	mov 	ecx, dword [pcidevs_len]
	dec 	ecx
	pop	eax
	mov 	ebx, dword [p_nvme_devices]

	movzx 	edx, byte [eax + PCIDEV.bus]
	mov 	byte [ebx + pcidev.bus], dl
	movzx 	edx, byte [eax + PCIDEV.devfn]
	mov 	byte [ebx + pcidev.devfn], dl
	mov 	dword [ebx + pcidev.num], ecx

	pop 	edx
	jmp	.next_dev

.err_no_mem:
	pop     eax edx
	xor 	eax, eax
	ret

.exit_success:
	xor 	eax, eax
	inc 	eax
	ret

endp

proc device_is_compat stdcall, pci:dword

	push  	 esi edx ecx
	mov 	 esi, [pci]
	invoke 	 PciRead8, dword [esi + pcidev.bus], dword [esi + pcidev.devfn], PCI_header00.interrupt_line
	mov 	 byte [esi + pcidev.iline], al
	invoke   PciRead32, dword [esi + pcidev.bus], dword [esi + pcidev.devfn], PCI_header00.base_addr_0
	and      eax, 0xfffffff0
	test     eax, eax
	jz       .failure
	mov 	 edx, eax
	push 	 edx

	invoke   MapIoMem, eax, sizeof.NVME_MMIO, PG_SW+PG_NOCACHE
	test     eax, eax
	jz       .failure
	;DEBUGF   DBG_INFO, "(NVMe) MMIO allocated at: 0x%x\n", eax
	mov 	 dword [esi + pcidev.io_addr], eax
	mov 	 eax, dword [eax + NVME_MMIO.CAP + 4]
	and 	 eax, CAP_DSTRD
	mov 	 byte [esi + pcidev.dstrd], al
	
	; 1003h + ((2y + 1) * (4 << CAP.DSTRD))
	mov 	 eax, 4
	shl 	 ax, cl
	mov 	 ecx, NVM_ASQS
	shl 	 ecx, 1
	inc 	 ecx
	imul 	 ecx, eax
	add 	 ecx, 0x1003

	pop 	 edx
	invoke 	 MapIoMem, edx, ecx, PG_SW+PG_NOCACHE
	mov 	 dword [esi + pcidev.io_addr], eax
	mov 	 eax, dword [eax + NVME_MMIO.VS]
	DEBUGF   DBG_INFO, "nvme%u: Controller version: 0x%x\n", [esi + pcidev.num], eax
	mov 	 dword [esi + pcidev.version], eax
	pop 	 ecx edx esi
	xor 	 eax, eax
	inc 	 eax
	ret

.failure:
	PDEBUGF  DBG_INFO, "PCI(%u.%u.%u): something went wrong checking NVMe device compatibility\n", byte [esi + pcidev.bus], byte [esi + pcidev.devfn]
	pop 	 ecx edx esi
	xor      eax, eax
	ret
	
endp

; nvme_init: Initializes the NVMe controller 
proc nvme_init stdcall, pci:dword

	push 	 ebx esi edi
	mov 	 esi, dword [pci]
	mov      edi, dword [esi + pcidev.io_addr]

	if 0
		mov    eax, dword [edi + NVME_MMIO.CAP]
		DEBUGF DBG_INFO, "(NVMe) CAP (0-31): 0x%x\n", eax
		mov    eax, dword [edi + NVME_MMIO.CAP + 4]
		DEBUGF DBG_INFO, "(NVMe) CAP (32-63): 0x%x\n", eax
		mov    eax, dword [edi + NVME_MMIO.CC]
		DEBUGF DBG_INFO, "(NVMe) CC: 0x%x\n", eax
		mov    eax, dword [edi + NVME_MMIO.CSTS]
		DEBUGF DBG_INFO, "(NVMe) CSTS: 0x%x\n", eax
	end if

	; check maximum queue entries supported
	mov 	ax, word [edi + NVME_MMIO.CAP]
	cmp 	ax, SQ_ENTRIES
	jb 	.exit_fail
	
	; For some reason, bit 7 (No I/O command set supported) is also set to 1 despite bit 0 (NVM command set)
	    ; being set to 1.. so I am not sure if bit 7 should be checked at all.. investigate later.
	mov      eax, dword [edi + NVME_MMIO.CAP + 4]
	test 	 eax, CAP_CSS_NVM_CMDSET
	jz       .exit_fail

	; Reset controller before we configure it
	stdcall nvme_controller_reset, esi
	if __DEBUG__
	stdcall nvme_wait, edi
	end if
	mov 	eax, dword [edi + NVME_MMIO.CAP + 4]
	and 	eax, CAP_MPSMIN
	shr 	eax, 16
	cmp 	eax, NVM_MPS
	ja 	.exit_fail
	mov 	eax, dword [edi + NVME_MMIO.CAP + 4]
	and 	eax, CAP_MPSMAX
	shr 	eax, 20
	cmp 	eax, NVM_MPS
	jb	.exit_fail

	; Configure IOSQES, IOCQES, AMS, MPS, CSS
	and 	dword [edi + NVME_MMIO.CC], not (CC_AMS or CC_MPS or CC_CSS or CC_IOSQES or CC_IOCQES)
	mov 	eax, dword [edi + NVME_MMIO.CC]
	; 	CSS = 0 (NVM Command Set)
	; 	AMS = 0 (Round Robin)
	; 	MPS = 0 (4KiB Pages)
	; 	IOSQES = 6 (64B)
	; 	IOCQES = 4 (16B)
	or 	eax, (4 shl 20) or (6 shl 16)
	mov 	dword [edi + NVME_MMIO.CC], eax

	; Configure Admin Queue Attributes
	mov 	eax, dword [edi + NVME_MMIO.AQA]
	and 	eax, not (AQA_ASQS or AQA_ACQS)
	or 	eax, NVM_ASQS or (NVM_ACQS shl 16)
	mov 	dword [edi + NVME_MMIO.AQA], eax

	; Allocate list of queues
	invoke  KernelAlloc, sizeof.NVM_QUEUE_ENTRY * (LAST_QUEUE_ID + 1)
	test 	eax, eax
	jz 	.exit_fail
	mov 	dword [esi + pcidev.queue_entries], eax
	mov 	edi, eax
	stdcall memsetdz, eax, sizeof.NVM_QUEUE_ENTRY * (LAST_QUEUE_ID + 1) / 4

	; Allocate submission/completion queue pointers
	; TODO: Make these queues physically contiguous
	xor 	ecx, ecx
@@:
	push 	ecx
	invoke  CreateRingBuffer, 0x1000, PG_SW
	pop 	ecx
	test 	eax, eax
	jz 	.exit_fail
	mov 	dword [edi + ecx + NVM_QUEUE_ENTRY.sq_ptr], eax
	push 	ecx
	stdcall memsetdz, eax, sizeof.CQ_ENTRY * CQ_ENTRIES / 4
	invoke  CreateRingBuffer, 0x1000, PG_SW
	pop 	ecx
	test 	eax, eax
	jz 	.exit_fail
	mov 	dword [edi + ecx + NVM_QUEUE_ENTRY.cq_ptr], eax
	push 	ecx
	stdcall memsetdz, eax, sizeof.CQ_ENTRY * CQ_ENTRIES / 4
	pop 	ecx
	mov 	dword [edi + ecx + NVM_QUEUE_ENTRY.phase_tag], CQ_PHASE_TAG
	add 	ecx, sizeof.NVM_QUEUE_ENTRY
	cmp 	ecx, (LAST_QUEUE_ID + 1) * sizeof.NVM_QUEUE_ENTRY
	jne 	@b

	; Configure Admin Submission/Completion Queue Base Address
	mov 	esi, [pci]
	mov 	esi, dword [esi + pcidev.io_addr]
	mov 	eax, dword [edi + NVM_QUEUE_ENTRY.sq_ptr]
	invoke  GetPhysAddr
	mov 	dword [esi + NVME_MMIO.ASQ], eax
	mov 	dword [esi + NVME_MMIO.ASQ + 4], 0

	mov 	eax, dword [edi + NVM_QUEUE_ENTRY.cq_ptr]
	invoke  GetPhysAddr
	mov 	dword [esi + NVME_MMIO.ACQ], eax
	mov 	dword [esi + NVME_MMIO.ACQ + 4], 0

	; Attach interrupt handler
	mov 	esi, [pci]
	movzx 	eax, byte [esi + pcidev.iline]
	DEBUGF  DBG_INFO, "nvme%u: Attaching interrupt handler to IRQ %u\n", [esi + pcidev.num], eax
	invoke  AttachIntHandler, eax, irq_handler, 0
	test 	eax, eax
	jz 	.exit_fail
	DEBUGF  DBG_INFO, "nvme%u: Successfully attached interrupt handler\n", [esi + pcidev.num]

	; Restart the controller
	stdcall nvme_controller_start, esi

	invoke  KernelAlloc, 0x1000
	test 	eax, eax
	jz 	.exit_fail
	mov 	edi, eax
	invoke  GetPhysAddr
	;                      pci:dword, nsid:dword, dptr:dword, cns:byte
	stdcall nvme_identify, [pci],     0,          eax,        CNS_IDCS
	mov 	eax, dword [edi + IDENTC.nn]
	mov 	dword [esi + pcidev.nn], eax
	DEBUGF  DBG_INFO, "nvme%u: Namespace Count: %u\n", [esi + pcidev.num], eax
	lea 	ebx, byte [edi + IDENTC.sn]
	lea 	eax, byte [esi + pcidev.serial]
	stdcall memcpy, eax, ebx, 20
	DEBUGF  DBG_INFO, "nvme%u: Serial Number: %s\n", [esi + pcidev.num], eax
	add 	ebx, 20
	lea 	eax, byte [esi + pcidev.model]
	stdcall memcpy, eax, ebx, 40
	DEBUGF  DBG_INFO, "nvme%u: Model: %s\n", [esi + pcidev.num], eax
	mov 	edx, dword [esi + pcidev.version]
	
	cmp 	edx, VS140
	jb 	@f
	; This is a reserved field in pre-1.4 controllers
	mov 	al, byte [edi + IDENTC.cntrltype]
	cmp 	al, CNTRLTYPE_IO_CONTROLLER
	jne 	.exit_fail 	
	DEBUGF  DBG_INFO, "nvme%u: I/O controller detected...\n", [esi + pcidev.num]

@@:
	; TODO: check IDENTC.AVSCC
	mov 	al, byte [edi + IDENTC.sqes]
	and 	al, 11110000b
	cmp 	al, 0x60 ; maximum submission queue size should at least be 64 bytes
	jb 	.exit_fail
	mov 	al, byte [edi + IDENTC.cqes]
	and 	al, 11110000b
	and 	al, 0x40 ; maximum completion queue entry size should at least be 16 bytes
	jb 	.exit_fail
	invoke  KernelFree, edi

	mov 	eax, 1 or (1 shl 16) ; CDW11 (set the number of queues we want)
	stdcall set_features, [pci], NULLPTR, FID_NUMBER_OF_QUEUES, eax
	mov 	esi, [pci]
	mov 	esi, dword [esi + pcidev.queue_entries]
	mov 	esi, dword [esi + NVM_QUEUE_ENTRY.cq_ptr]
	mov 	eax, dword [esi + sizeof.CQ_ENTRY + CQ_ENTRY.cdw0]
	if __DEBUG__
	DEBUGF  DBG_INFO, "nvme%u: Set Features CDW0: 0x%x\n", [esi + pcidev.num], eax
	end if
	test 	ax, ax ; Number of I/O Submission Queues allocated
	jz 	.exit_fail
	shl 	eax, 16
	test 	ax, ax ; Number of I/O Completion Queues allocated
	jnz	.exit_fail

	; Create I/O Queues
	; (TODO: create N queue pairs for N CPU cores, see page 8 of NVMe 1.4 spec for an explaination
	mov 	esi, [pci]
	mov 	edi, esi
	mov 	esi, dword [esi + pcidev.queue_entries]
	lea 	esi, [esi + sizeof.NVM_QUEUE_ENTRY]
	mov 	eax, dword [esi + NVM_QUEUE_ENTRY.cq_ptr]
	invoke 	GetPhysAddr
	stdcall create_io_completion_queue, [pci], eax, 1, IEN_ON
	DEBUGF  DBG_INFO, "nvme%u: Successfully created I/O completion queue 1\n", [edi + pcidev.num]
	mov 	eax, dword [esi + NVM_QUEUE_ENTRY.sq_ptr]
	invoke 	GetPhysAddr
	stdcall create_io_submission_queue, [pci], eax, 1, 1
	DEBUGF  DBG_INFO, "nvme%u: Successfully created I/O submission queue 1\n", [edi + pcidev.num]

	if 1
		stdcall determine_active_nsids, [pci]
		test 	eax, eax
		jz 	.exit_fail ; No active NSIDS
		mov 	esi, [pci]
		mov 	dword [esi + pcidev.nsid], eax
		DEBUGF  DBG_INFO, "nvme%u: Found active NSID: %u\n", [esi + pcidev.num], eax
	else
		mov 	esi, [pci]
		xor 	eax, eax
		inc 	eax
		mov 	dword [esi + pcidev.nsid], eax
	end if

	invoke  KernelAlloc, 0x1000
	test 	eax, eax
	jz 	.exit_fail
	mov 	edi, eax
	invoke  GetPhysAddr
	stdcall nvme_identify, [pci], [esi + pcidev.nsid], eax, CNS_IDNS
	invoke  KernelAlloc, sizeof.NSINFO
	test 	eax, eax
	jz 	.exit_fail
	mov 	ebx, eax
	mov 	dword [esi + pcidev.nsinfo], eax
	mov 	al, byte [edi + IDENTN.nsfeat]
	mov 	byte [ebx + NSINFO.features], al
	DEBUGF  DBG_INFO, "nvme%un%u: Namespace Features: 0x%x\n", [esi + pcidev.num], [esi + pcidev.nsid], al
	mov 	dword [ebx + NSINFO.pci], esi
	mov 	eax, dword [edi + IDENTN.nsze]
	mov 	dword [ebx + NSINFO.size], eax
	mov 	eax, dword [edi + IDENTN.nsze + 4]
	mov 	dword [ebx + NSINFO.size + 4], eax
	mov 	eax, dword [edi + IDENTN.ncap]
	mov 	dword [ebx + NSINFO.capacity], eax 
	mov 	eax, dword [edi + IDENTN.ncap + 4]
	mov 	dword [ebx + NSINFO.capacity + 4], eax 
	DEBUGF  DBG_INFO, "nvme%un%u: Namespace Size: %u + %u logical blocks\n", [esi + pcidev.num], [esi + pcidev.nsid], [edi + IDENTN.nsze], [edi + IDENTN.nsze + 4]
	DEBUGF  DBG_INFO, "nvme%un%u: Namespace Capacity: %u + %u logical blocks\n", [esi + pcidev.num], [esi + pcidev.nsid], [edi + IDENTN.ncap], [edi + IDENTN.ncap + 4]
	mov 	eax, dword [edi + IDENTN.lbaf0]
	shr 	eax, 16 ; Get LBADS
	and 	eax, 0xff
	stdcall pow2, eax
	mov 	dword [ebx + NSINFO.lbads], eax
	DEBUGF  DBG_INFO, "nvme%un%u: Namespace LBA Data Size: %u\n", [esi + pcidev.num], [esi + pcidev.nsid], eax
	invoke  KernelFree, edi
	invoke  KernelAlloc, 0x1000
	test 	eax, eax
	jz 	.exit_fail
	mov 	edi, eax
	invoke  KernelAlloc, 0x4
	test 	eax, eax
	jz 	.exit_fail
	mov 	edx, NVM_CMD_READ
	mov 	dword [eax], 0x1
	stdcall nvme_readwrite, [esi + pcidev.nsinfo], edi, 1, eax
	test 	eax, eax
	jz 	.exit_fail
	DEBUGF  DBG_INFO, "nvme%u: Successfully initialized driver\n", [esi + pcidev.num]
      	xor     eax, eax
      	inc     eax
	pop 	edi esi ebx
      	ret

.exit_fail:
	if __DEBUG__
	mov 	esi, [pci]
	DEBUGF  DBG_INFO, "nvme%u: failed to initialize controller\n", [esi + pcidev.num]
	end if
	xor 	eax, eax
	pop 	edi esi ebx
	ret

endp

proc get_new_cid stdcall, pci:dword, y:dword

	push 	esi
	mov 	esi, [pci]
	mov 	esi, [esi + pcidev.queue_entries]
	mov 	ecx, [y]
	imul 	ecx, sizeof.NVM_QUEUE_ENTRY
	movzx 	eax, word [esi + ecx + NVM_QUEUE_ENTRY.tail]
	pop 	esi
	ret

endp

proc nvme_controller_reset stdcall, pci:dword

	push 	esi edi
	mov 	esi, [pci]
	DEBUGF  DBG_INFO, "nvme%u: Resetting Controller...\n", [esi + pcidev.num]
	mov 	edi, dword [esi + pcidev.io_addr]
	and 	dword [edi + NVME_MMIO.CC], 0xfffffffe ; CC.EN = 0

; Wait for controller to be brought to idle state, CSTS.RDY should be cleared to 0 when this happens
.wait:
	test    dword [edi + NVME_MMIO.CSTS], CSTS_RDY
	jnz 	.wait
	DEBUGF  DBG_INFO, "nvme%u: Successfully reset controller...\n", [esi + pcidev.num]
	pop 	edi esi
	ret

endp

proc nvme_controller_start stdcall, pci:dword

	push 	esi edi
	mov 	esi, [pci]
	DEBUGF  DBG_INFO, "nvme%u: Starting Controller...\n", [esi + pcidev.num]
	mov 	edi, dword [esi + pcidev.io_addr]
	or 	dword [edi + NVME_MMIO.CC], 1 ; CC.EN = 1

; Wait for controller to be brought into active state, CSTS.RDY should be set to 1 when this happens
.wait:
	test 	dword [edi + NVME_MMIO.CSTS], CSTS_RDY
	jz 	.wait
	DEBUGF  DBG_INFO, "nvme%u: Successfully started controller...\n", [esi + pcidev.num]
	pop 	edi esi
	ret

endp

; Should be called only after the value of CC.EN has changed
proc nvme_wait stdcall, mmio:dword

	push 	esi
	mov 	esi, [mmio]
	mov 	esi, dword [esi + NVME_MMIO.CAP]
	and 	esi, CAP_TO
	shr 	esi, 24
	imul 	esi, 150 ; TODO: bad time delay, set to appropriate value later
	invoke  Sleep
	pop 	esi
	ret

endp

; Writes to completion queue 'y' head doorbell
proc cqyhdbl_write stdcall, pci:dword, y:dword, cqh:dword

	push 	esi edi
	mov 	esi, [pci]

	; 1000h + ((2y + 1) * (4 << CAP.DSTRD))
	mov 	eax, [y]
	shl 	al, 1
	inc 	al
	mov 	edx, 4
	mov 	cl, byte [esi + pcidev.dstrd]
	shl 	dx, cl
	imul 	dx, ax
	add 	dx, 0x1000
	mov 	ecx, [y]
	imul 	ecx, sizeof.NVM_QUEUE_ENTRY
	mov 	edi, dword [esi + pcidev.queue_entries]
	lea 	edi, dword [edi + ecx]
	mov 	esi, dword [esi + pcidev.io_addr]
	mov 	eax, [cqh]
	;DEBUGF  DBG_INFO, "(NVMe) Writing to completion queue doorbell register 0x%x: %u\n", dx, ax
	mov 	word [esi + edx], ax ; Write to CQyHDBL
	mov 	word [edi + NVM_QUEUE_ENTRY.head], ax
	pop 	edi esi
	ret

endp

; Writes to submission queue 'y' tail doorbell
proc sqytdbl_write stdcall, pci:dword, y:word, cmd:dword

	push 	ebx esi edi
	mov 	edi, [pci]
	mov 	edi, dword [edi + pcidev.queue_entries]
	movzx 	ecx, [y]
	imul 	ecx, sizeof.NVM_QUEUE_ENTRY
	mov 	edi, dword [edi + ecx + NVM_QUEUE_ENTRY.sq_ptr]
	mov 	esi, [cmd]
	mov 	ecx, dword [esi + SQ_ENTRY.cdw0]
	shr 	ecx, 16 ; Get CID
	imul 	ecx, sizeof.SQ_ENTRY
	lea 	edi, [edi + ecx]
	stdcall memcpy, edi, esi, sizeof.SQ_ENTRY

	mov 	edi, [pci]
	mov 	esi, dword [edi + pcidev.io_addr]
	mov 	edi, dword [edi + pcidev.queue_entries]
	movzx 	ecx, [y]
	imul 	ecx, sizeof.NVM_QUEUE_ENTRY
	movzx 	eax, word [edi + ecx + NVM_QUEUE_ENTRY.tail]
	cmp 	ax, NVM_ASQS
	jb	@f 	
	xor 	ax, ax
	
@@:
	mov 	esi, [pci]
	inc 	ax
	; 1000h + (2y * (4 << CAP.DSTRD))
	movzx 	ebx, [y]
	shl 	ebx, 1
	mov 	edx, 4
	mov 	cl, byte [esi + pcidev.dstrd]
	shl 	edx, cl
	imul 	edx, ebx
	add 	edx, 0x1000
	mov 	esi, dword [esi + pcidev.io_addr]
	mov 	word [esi + edx], ax
	movzx 	ecx, [y]
	imul 	ecx, sizeof.NVM_QUEUE_ENTRY
	mov 	word [edi + ecx + NVM_QUEUE_ENTRY.tail], ax
	dec 	ax
	movzx 	ecx, [y]
	stdcall nvme_cmd_wait, [pci], ecx, eax
	pop 	edi esi ebx
	ret

endp

; Calculates 2^x
proc pow2 stdcall, x:byte 

	push 	ecx
	mov 	cl, [x]
	xor 	eax, eax
	inc 	eax
	test 	cl, cl
	jnz 	@f
	pop 	ecx
	ret

@@:
	shl 	eax, cl
	pop 	ecx
	ret
	
endp

proc nvme_cmd_wait stdcall, pci:dword, y:dword, cid:word
	
	push 	esi
	mov 	esi, [pci]
	movzx 	ecx, word [cid]
	mov 	edx, [y]
	imul 	edx, sizeof.NVM_QUEUE_ENTRY
	mov 	esi, dword [esi + pcidev.queue_entries]
	lea 	esi, [esi + edx]
	imul 	ecx, sizeof.CQ_ENTRY
	mov 	eax, dword [esi + NVM_QUEUE_ENTRY.phase_tag]
	mov 	esi, dword [esi + NVM_QUEUE_ENTRY.cq_ptr]
	test 	eax, CQ_PHASE_TAG
	jnz 	.phase_tag_1	
	
@@:
	test 	byte [esi + ecx + CQ_ENTRY.status], CQ_PHASE_TAG
	jnz 	@b
	pop 	esi
	ret

.phase_tag_1:
	;DEBUGF  DBG_INFO, "status: %x\n", [esi + ecx + CQ_ENTRY.status]
	test	byte [esi + ecx + CQ_ENTRY.status], CQ_PHASE_TAG
	jz 	.phase_tag_1
	pop 	esi
	ret

endp

proc is_queue_full stdcall, tail:word, head:word
	
	push 	bx
	mov 	ax, [tail]
	mov 	bx, [head]
	cmp 	ax, bx
	je 	.not_full
	test 	bx, bx
	jnz 	@f
	cmp 	ax, NVM_ASQS
	jne 	@f
	xor 	eax, eax
	inc 	eax
	ret

@@:
	cmp 	ax, bx
	jae 	.not_full
	sub 	ax, bx
	cmp 	ax, 1
	jne 	.not_full
	xor 	eax, eax
	inc 	eax
	ret
	
.not_full:
	pop 	bx
	xor 	eax, eax
	ret

endp

proc consume_cq_entries stdcall, pci:dword, queue:dword

	push 	esi edi
	mov 	esi, [pci]
	mov 	ecx, [queue]
	imul 	ecx, sizeof.NVM_QUEUE_ENTRY
	mov 	esi, dword [esi + pcidev.queue_entries]
	lea 	esi, [esi + ecx]
	mov 	edi, dword [esi + NVM_QUEUE_ENTRY.cq_ptr]
	movzx 	eax, word [esi + NVM_QUEUE_ENTRY.tail]
	movzx 	ecx, word [esi + NVM_QUEUE_ENTRY.head]
	stdcall is_queue_full, eax, ecx
	test 	eax, eax
	jnz 	.end
	movzx 	ecx, word [esi + NVM_QUEUE_ENTRY.head]
	
.loop:
	cmp 	cx, word [esi + NVM_QUEUE_ENTRY.tail]
	je 	.end
	mov 	edx, ecx
	imul 	edx, sizeof.CQ_ENTRY
	mov 	ax, word [edi + edx + CQ_ENTRY.status]
	DEBUGF  DBG_INFO, "Status: 0x%x\n", ax
	inc 	cx
	push 	ecx
	stdcall cqyhdbl_write, [pci], [queue], ecx
	pop 	ecx
	jmp 	.loop

.end:
	pop 	edi esi
	xor 	eax, eax
	ret

endp

proc irq_handler

	push 	esi edi
	mov 	esi, dword [p_nvme_devices]

	; check if the NVMe device generated an interrupt
	invoke 	PciRead16, dword [esi + pcidev.bus], dword [esi + pcidev.devfn], PCI_header00.status
	test 	al, 1000b ; check interrupt status
	jz 	.not_our_irq
	
	mov 	edi, dword [esi + pcidev.io_addr]
	mov 	dword [edi + NVME_MMIO.INTMS], 0x3
	xor 	ecx, ecx

@@:
	push 	ecx
	stdcall consume_cq_entries, [p_nvme_devices], ecx
	pop 	ecx
	inc 	ecx
	cmp 	ecx, LAST_QUEUE_ID
	jng 	@b

	; Interrupt handled by driver, return 1
	mov 	dword [edi + NVME_MMIO.INTMC], 0x3
	pop 	edi esi
	xor 	eax, eax
	inc 	eax
	ret

.not_our_irq:
	; Interrupt not handled by driver, return 0
	pop 	edi esi
	xor 	eax, eax
	ret

endp

proc nvme_cleanup

	DEBUGF  DBG_INFO, "(NVMe): Cleaning up...\n"
	mov 	ecx, dword [pcidevs_len]
	mov 	eax, dword [p_nvme_devices]
	test 	eax, eax
	jnz 	.loop
	ret

.loop:
	;invoke  KernelFree, dword [p_nvme_devices + ecx * sizeof.pcidev + pcidev.ident_ptr]
	dec 	ecx
	test 	ecx, ecx
	jnz 	.loop
	invoke  KernelFree, dword [p_nvme_devices]

@@:
	ret

endp

;all initialized data place here
align 4
	p_nvme_devices dd 0
	pcidevs_len  dd 0
	my_service   db "NVMe",0  ;max 16 chars include zero
	disk_functions:
		dd 	 disk_functions.end - disk_functions
		dd 	 0 ; no close function
		dd 	 0 ; no closemedia function
		dd 	 nvme_query_media
		dd 	 0 ; no read function (for now)
		dd 	 0 ; no write function (for now)
		dd 	 0 ; no flush function
		dd 	 0 ; use default cache size
	.end:
	if __DEBUG__
	include_debug_strings
	end if

align 4
data fixups
end data