Kernel: Move the Storage directory to be a new directory under Devices

The Storage subsystem, like the Audio and HID subsystems, exposes Unix
device files (for example, in the /dev directory). To ensure consistency
across the repository, we should make the Storage subsystem to reside in
the Kernel/Devices directory like the two other mentioned subsystems.

Kernel/Devices/Storage/NVMe/NVMeDefinitions.h

@@ -0,0 +1,216 @@
+/*
+ * Copyright (c) 2021, Pankaj R <pankydev8@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Endian.h>
+#include <AK/Types.h>
+
+struct ControllerRegister {
+    u64 cap;
+    u32 vs;
+    u32 intms;
+    u32 intmc;
+    u32 cc;
+    u32 rsvd1;
+    u32 csts;
+    u32 nssr;
+    u32 aqa;
+    u64 asq;
+    u64 acq;
+    u64 rsvd2[505];
+};
+
+struct IdentifyNamespace {
+    u64 nsze;
+    u64 ncap;
+    u8 rsdv1[10];
+    u8 flbas;
+    u8 rsvd2[100];
+    u32 lbaf[16];
+    u64 rsvd3[488];
+};
+
+// DOORBELL
+static constexpr u32 REG_SQ0TDBL_START = 0x1000;
+static constexpr u32 REG_SQ0TDBL_END = 0x1003;
+static constexpr u8 DBL_REG_SIZE = 8;
+// CAP
+static constexpr u8 CAP_DBL_SHIFT = 32;
+static constexpr u8 CAP_DBL_MASK = 0xf;
+static constexpr u8 CAP_TO_SHIFT = 24;
+static constexpr u64 CAP_TO_MASK = 0xff << CAP_TO_SHIFT;
+static constexpr u16 MQES(u64 cap)
+{
+    return (cap & 0xffff) + 1;
+}
+
+static constexpr u32 CAP_TO(u64 cap)
+{
+    return (cap & CAP_TO_MASK) >> CAP_TO_SHIFT;
+}
+
+// CC – Controller Configuration
+static constexpr u8 CC_EN_BIT = 0x0;
+static constexpr u8 CSTS_RDY_BIT = 0x0;
+static constexpr u8 CSTS_SHST_SHIFT = 2;
+static constexpr u32 CSTS_SHST_MASK = 0x3 << CSTS_SHST_SHIFT;
+static constexpr u8 CC_IOSQES_BIT = 16;
+static constexpr u8 CC_IOCQES_BIT = 20;
+
+static constexpr u32 CSTS_SHST(u32 x)
+{
+    return (x & CSTS_SHST_MASK) >> CSTS_SHST_SHIFT;
+}
+
+static constexpr u16 CC_AQA_MASK = (0xfff);
+static constexpr u16 ACQ_SIZE(u32 x)
+{
+    return (x >> 16) & CC_AQA_MASK;
+}
+static constexpr u16 ASQ_SIZE(u32 x)
+{
+    return x & CC_AQA_MASK;
+}
+static constexpr u8 CQ_WIDTH = 4; // CQ is 16 bytes(2^4) in size.
+static constexpr u8 SQ_WIDTH = 6; // SQ size is 64 bytes(2^6) in size.
+static constexpr u16 CQ_SIZE(u16 q_depth)
+{
+    return q_depth << CQ_WIDTH;
+}
+static constexpr u16 SQ_SIZE(u16 q_depth)
+{
+    return q_depth << SQ_WIDTH;
+}
+static constexpr u8 PHASE_TAG(u16 x)
+{
+    return x & 0x1;
+}
+static constexpr u16 CQ_STATUS_FIELD_MASK = 0xfffe;
+static constexpr u16 CQ_STATUS_FIELD(u16 x)
+{
+    return (x & CQ_STATUS_FIELD_MASK) >> 1;
+}
+
+static constexpr u16 IO_QUEUE_SIZE = 64; // TODO:Need to be configurable
+
+// IDENTIFY
+static constexpr u16 NVMe_IDENTIFY_SIZE = 4096;
+static constexpr u8 NVMe_CNS_ID_ACTIVE_NS = 0x2;
+static constexpr u8 NVMe_CNS_ID_NS = 0x0;
+static constexpr u8 FLBA_SIZE_INDEX = 26;
+static constexpr u8 FLBA_SIZE_MASK = 0xf;
+static constexpr u8 LBA_FORMAT_SUPPORT_INDEX = 128;
+static constexpr u32 LBA_SIZE_MASK = 0x00ff0000;
+
+// OPCODES
+// ADMIN COMMAND SET
+enum AdminCommandOpCode {
+    OP_ADMIN_CREATE_COMPLETION_QUEUE = 0x5,
+    OP_ADMIN_CREATE_SUBMISSION_QUEUE = 0x1,
+    OP_ADMIN_IDENTIFY = 0x6,
+};
+
+// IO opcodes
+enum IOCommandOpcode {
+    OP_NVME_WRITE = 0x1,
+    OP_NVME_READ = 0x2
+};
+
+// FLAGS
+static constexpr u8 QUEUE_PHY_CONTIGUOUS = (1 << 0);
+static constexpr u8 QUEUE_IRQ_ENABLED = (1 << 1);
+static constexpr u8 QUEUE_IRQ_DISABLED = (0 << 1);
+
+struct [[gnu::packed]] NVMeCompletion {
+    LittleEndian<u32> cmd_spec;
+    LittleEndian<u32> res;
+
+    LittleEndian<u16> sq_head; /* how much of this queue may be reclaimed */
+    LittleEndian<u16> sq_id;   /* submission queue that generated this entry */
+
+    u16 command_id;           /* of the command which completed */
+    LittleEndian<u16> status; /* did the command fail, and if so, why? */
+};
+
+struct [[gnu::packed]] DataPtr {
+    LittleEndian<u64> prp1;
+    LittleEndian<u64> prp2;
+};
+
+struct [[gnu::packed]] NVMeGenericCmd {
+    LittleEndian<u32> nsid;
+    LittleEndian<u64> rsvd;
+    LittleEndian<u64> metadata;
+    struct DataPtr data_ptr;
+    LittleEndian<u32> cdw10;
+    LittleEndian<u32> cdw11;
+    LittleEndian<u32> cdw12;
+    LittleEndian<u32> cdw13;
+    LittleEndian<u32> cdw14;
+    LittleEndian<u32> cdw15;
+};
+
+struct [[gnu::packed]] NVMeRWCmd {
+    LittleEndian<u32> nsid;
+    LittleEndian<u64> rsvd;
+    LittleEndian<u64> metadata;
+    struct DataPtr data_ptr;
+    LittleEndian<u64> slba;
+    LittleEndian<u16> length;
+    LittleEndian<u16> control;
+    LittleEndian<u32> dsmgmt;
+    LittleEndian<u32> reftag;
+    LittleEndian<u16> apptag;
+    LittleEndian<u16> appmask;
+};
+
+struct [[gnu::packed]] NVMeIdentifyCmd {
+    LittleEndian<u32> nsid;
+    LittleEndian<u64> rsvd1[2];
+    struct DataPtr data_ptr;
+    u8 cns;
+    u8 rsvd2;
+    LittleEndian<u16> ctrlid;
+    u8 rsvd3[3];
+    u8 csi;
+    u64 rsvd4[2];
+};
+
+struct [[gnu::packed]] NVMeCreateCQCmd {
+    u32 rsvd1[5];
+    LittleEndian<u64> prp1;
+    u64 rsvd2;
+    LittleEndian<u16> cqid;
+    LittleEndian<u16> qsize;
+    LittleEndian<u16> cq_flags;
+    LittleEndian<u16> irq_vector;
+    u64 rsvd12[2];
+};
+
+struct [[gnu::packed]] NVMeCreateSQCmd {
+    u32 rsvd1[5];
+    LittleEndian<u64> prp1;
+    u64 rsvd2;
+    LittleEndian<u16> sqid;
+    LittleEndian<u16> qsize;
+    LittleEndian<u16> sq_flags;
+    LittleEndian<u16> cqid;
+    u64 rsvd12[2];
+};
+
+struct [[gnu::packed]] NVMeSubmission {
+    u8 op;
+    u8 flags;
+    LittleEndian<u16> cmdid;
+    union [[gnu::packed]] {
+        NVMeGenericCmd generic;
+        NVMeIdentifyCmd identify;
+        NVMeRWCmd rw;
+        NVMeCreateCQCmd create_cq;
+        NVMeCreateSQCmd create_sq;
+    };
+};