docs: move xtensa documentation under Documentation/arch/

Architecture-specific documentation is being moved into Documentation/arch/
as a way of cleaning up the top-level documentation directory and making
the docs hierarchy more closely match the source hierarchy.  Move
Documentation/xtensa into arch/ and fix all in-tree references.

Cc: Chris Zankel <chris@zankel.net>
Reviewed-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

5 files changed, 0 insertions, 288 deletions

diff --git a/Documentation/xtensa/atomctl.rst b/Documentation/xtensa/atomctl.rst
deleted file mode 100644
index 1ecbd0ba9a2e..000000000000
--- a/Documentation/xtensa/atomctl.rst
+++ /dev/null
@@ -1,51 +0,0 @@
-===========================================
-Atomic Operation Control (ATOMCTL) Register
-===========================================
-
-We Have Atomic Operation Control (ATOMCTL) Register.
-This register determines the effect of using a S32C1I instruction
-with various combinations of:
-
-     1. With and without an Coherent Cache Controller which
-        can do Atomic Transactions to the memory internally.
-
-     2. With and without An Intelligent Memory Controller which
-        can do Atomic Transactions itself.
-
-The Core comes up with a default value of for the three types of cache ops::
-
-      0x28: (WB: Internal, WT: Internal, BY:Exception)
-
-On the FPGA Cards we typically simulate an Intelligent Memory controller
-which can implement  RCW transactions. For FPGA cards with an External
-Memory controller we let it to the atomic operations internally while
-doing a Cached (WB) transaction and use the Memory RCW for un-cached
-operations.
-
-For systems without an coherent cache controller, non-MX, we always
-use the memory controllers RCW, thought non-MX controlers likely
-support the Internal Operation.
-
-CUSTOMER-WARNING:
-   Virtually all customers buy their memory controllers from vendors that
-   don't support atomic RCW memory transactions and will likely want to
-   configure this register to not use RCW.
-
-Developers might find using RCW in Bypass mode convenient when testing
-with the cache being bypassed; for example studying cache alias problems.
-
-See Section 4.3.12.4 of ISA; Bits::
-
-                             WB     WT      BY
-                           5   4 | 3   2 | 1   0
-
-=========    ==================      ==================      ===============
-  2 Bit
-  Field
-  Values     WB - Write Back         WT - Write Thru         BY - Bypass
-=========    ==================      ==================      ===============
-    0        Exception               Exception               Exception
-    1        RCW Transaction         RCW Transaction         RCW Transaction
-    2        Internal Operation      Internal Operation      Reserved
-    3        Reserved                Reserved                Reserved
-=========    ==================      ==================      ===============
diff --git a/Documentation/xtensa/booting.rst b/Documentation/xtensa/booting.rst
deleted file mode 100644
index e1b83707e5b6..000000000000
--- a/Documentation/xtensa/booting.rst
+++ /dev/null
@@ -1,22 +0,0 @@
-=====================================
-Passing boot parameters to the kernel
-=====================================
-
-Boot parameters are represented as a TLV list in the memory. Please see
-arch/xtensa/include/asm/bootparam.h for definition of the bp_tag structure and
-tag value constants. First entry in the list must have type BP_TAG_FIRST, last
-entry must have type BP_TAG_LAST. The address of the first list entry is
-passed to the kernel in the register a2. The address type depends on MMU type:
-
-- For configurations without MMU, with region protection or with MPU the
-  address must be the physical address.
-- For configurations with region translarion MMU or with MMUv3 and CONFIG_MMU=n
-  the address must be a valid address in the current mapping. The kernel will
-  not change the mapping on its own.
-- For configurations with MMUv2 the address must be a virtual address in the
-  default virtual mapping (0xd0000000..0xffffffff).
-- For configurations with MMUv3 and CONFIG_MMU=y the address may be either a
-  virtual or physical address. In either case it must be within the default
-  virtual mapping. It is considered physical if it is within the range of
-  physical addresses covered by the default KSEG mapping (XCHAL_KSEG_PADDR..
-  XCHAL_KSEG_PADDR + XCHAL_KSEG_SIZE), otherwise it is considered virtual.
diff --git a/Documentation/xtensa/features.rst b/Documentation/xtensa/features.rst
deleted file mode 100644
index 6b92c7bfa19d..000000000000
--- a/Documentation/xtensa/features.rst
+++ /dev/null
@@ -1,3 +0,0 @@
-.. SPDX-License-Identifier: GPL-2.0
-
-.. kernel-feat:: $srctree/Documentation/features xtensa
diff --git a/Documentation/xtensa/index.rst b/Documentation/xtensa/index.rst
deleted file mode 100644
index 69952446a9be..000000000000
--- a/Documentation/xtensa/index.rst
+++ /dev/null
@@ -1,14 +0,0 @@
-.. SPDX-License-Identifier: GPL-2.0
-
-===================
-Xtensa Architecture
-===================
-
-.. toctree::
-   :maxdepth: 1
-
-   atomctl
-   booting
-   mmu
-
-   features
diff --git a/Documentation/xtensa/mmu.rst b/Documentation/xtensa/mmu.rst
deleted file mode 100644
index 450573afa31a..000000000000
--- a/Documentation/xtensa/mmu.rst
+++ /dev/null
@@ -1,198 +0,0 @@
-=============================
-MMUv3 initialization sequence
-=============================
-
-The code in the initialize_mmu macro sets up MMUv3 memory mapping
-identically to MMUv2 fixed memory mapping. Depending on
-CONFIG_INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX symbol this code is
-located in addresses it was linked for (symbol undefined), or not
-(symbol defined), so it needs to be position-independent.
-
-The code has the following assumptions:
-
-  - This code fragment is run only on an MMU v3.
-  - TLBs are in their reset state.
-  - ITLBCFG and DTLBCFG are zero (reset state).
-  - RASID is 0x04030201 (reset state).
-  - PS.RING is zero (reset state).
-  - LITBASE is zero (reset state, PC-relative literals); required to be PIC.
-
-TLB setup proceeds along the following steps.
-
-  Legend:
-
-    - VA = virtual address (two upper nibbles of it);
-    - PA = physical address (two upper nibbles of it);
-    - pc = physical range that contains this code;
-
-After step 2, we jump to virtual address in the range 0x40000000..0x5fffffff
-or 0x00000000..0x1fffffff, depending on whether the kernel was loaded below
-0x40000000 or above. That address corresponds to next instruction to execute
-in this code. After step 4, we jump to intended (linked) address of this code.
-The scheme below assumes that the kernel is loaded below 0x40000000.
-
- ====== =====  =====  =====  =====   ====== =====  =====
- -      Step0  Step1  Step2  Step3          Step4  Step5
-
-   VA      PA     PA     PA     PA     VA      PA     PA
- ====== =====  =====  =====  =====   ====== =====  =====
- E0..FF -> E0  -> E0  -> E0          F0..FF -> F0  -> F0
- C0..DF -> C0  -> C0  -> C0          E0..EF -> F0  -> F0
- A0..BF -> A0  -> A0  -> A0          D8..DF -> 00  -> 00
- 80..9F -> 80  -> 80  -> 80          D0..D7 -> 00  -> 00
- 60..7F -> 60  -> 60  -> 60
- 40..5F -> 40         -> pc  -> pc   40..5F -> pc
- 20..3F -> 20  -> 20  -> 20
- 00..1F -> 00  -> 00  -> 00
- ====== =====  =====  =====  =====   ====== =====  =====
-
-The default location of IO peripherals is above 0xf0000000. This may be changed
-using a "ranges" property in a device tree simple-bus node. See the Devicetree
-Specification, section 4.5 for details on the syntax and semantics of
-simple-bus nodes. The following limitations apply:
-
-1. Only top level simple-bus nodes are considered
-
-2. Only one (first) simple-bus node is considered
-
-3. Empty "ranges" properties are not supported
-
-4. Only the first triplet in the "ranges" property is considered
-
-5. The parent-bus-address value is rounded down to the nearest 256MB boundary
-
-6. The IO area covers the entire 256MB segment of parent-bus-address; the
-   "ranges" triplet length field is ignored
-
-
-MMUv3 address space layouts.
-============================
-
-Default MMUv2-compatible layout::
-
-                        Symbol                   VADDR       Size
-  +------------------+
-  | Userspace        |                           0x00000000  TASK_SIZE
-  +------------------+                           0x40000000
-  +------------------+
-  | Page table       |  XCHAL_PAGE_TABLE_VADDR   0x80000000  XCHAL_PAGE_TABLE_SIZE
-  +------------------+
-  | KASAN shadow map |  KASAN_SHADOW_START       0x80400000  KASAN_SHADOW_SIZE
-  +------------------+                           0x8e400000
-  +------------------+
-  | VMALLOC area     |  VMALLOC_START            0xc0000000  128MB - 64KB
-  +------------------+  VMALLOC_END
-  +------------------+
-  | Cache aliasing   |  TLBTEMP_BASE_1           0xc8000000  DCACHE_WAY_SIZE
-  | remap area 1     |
-  +------------------+
-  | Cache aliasing   |  TLBTEMP_BASE_2                       DCACHE_WAY_SIZE
-  | remap area 2     |
-  +------------------+
-  +------------------+
-  | KMAP area        |  PKMAP_BASE                           PTRS_PER_PTE *
-  |                  |                                       DCACHE_N_COLORS *
-  |                  |                                       PAGE_SIZE
-  |                  |                                       (4MB * DCACHE_N_COLORS)
-  +------------------+
-  | Atomic KMAP area |  FIXADDR_START                        KM_TYPE_NR *
-  |                  |                                       NR_CPUS *
-  |                  |                                       DCACHE_N_COLORS *
-  |                  |                                       PAGE_SIZE
-  +------------------+  FIXADDR_TOP              0xcffff000
-  +------------------+
-  | Cached KSEG      |  XCHAL_KSEG_CACHED_VADDR  0xd0000000  128MB
-  +------------------+
-  | Uncached KSEG    |  XCHAL_KSEG_BYPASS_VADDR  0xd8000000  128MB
-  +------------------+
-  | Cached KIO       |  XCHAL_KIO_CACHED_VADDR   0xe0000000  256MB
-  +------------------+
-  | Uncached KIO     |  XCHAL_KIO_BYPASS_VADDR   0xf0000000  256MB
-  +------------------+
-
-
-256MB cached + 256MB uncached layout::
-
-                        Symbol                   VADDR       Size
-  +------------------+
-  | Userspace        |                           0x00000000  TASK_SIZE
-  +------------------+                           0x40000000
-  +------------------+
-  | Page table       |  XCHAL_PAGE_TABLE_VADDR   0x80000000  XCHAL_PAGE_TABLE_SIZE
-  +------------------+
-  | KASAN shadow map |  KASAN_SHADOW_START       0x80400000  KASAN_SHADOW_SIZE
-  +------------------+                           0x8e400000
-  +------------------+
-  | VMALLOC area     |  VMALLOC_START            0xa0000000  128MB - 64KB
-  +------------------+  VMALLOC_END
-  +------------------+
-  | Cache aliasing   |  TLBTEMP_BASE_1           0xa8000000  DCACHE_WAY_SIZE
-  | remap area 1     |
-  +------------------+
-  | Cache aliasing   |  TLBTEMP_BASE_2                       DCACHE_WAY_SIZE
-  | remap area 2     |
-  +------------------+
-  +------------------+
-  | KMAP area        |  PKMAP_BASE                           PTRS_PER_PTE *
-  |                  |                                       DCACHE_N_COLORS *
-  |                  |                                       PAGE_SIZE
-  |                  |                                       (4MB * DCACHE_N_COLORS)
-  +------------------+
-  | Atomic KMAP area |  FIXADDR_START                        KM_TYPE_NR *
-  |                  |                                       NR_CPUS *
-  |                  |                                       DCACHE_N_COLORS *
-  |                  |                                       PAGE_SIZE
-  +------------------+  FIXADDR_TOP              0xaffff000
-  +------------------+
-  | Cached KSEG      |  XCHAL_KSEG_CACHED_VADDR  0xb0000000  256MB
-  +------------------+
-  | Uncached KSEG    |  XCHAL_KSEG_BYPASS_VADDR  0xc0000000  256MB
-  +------------------+
-  +------------------+
-  | Cached KIO       |  XCHAL_KIO_CACHED_VADDR   0xe0000000  256MB
-  +------------------+
-  | Uncached KIO     |  XCHAL_KIO_BYPASS_VADDR   0xf0000000  256MB
-  +------------------+
-
-
-512MB cached + 512MB uncached layout::
-
-                        Symbol                   VADDR       Size
-  +------------------+
-  | Userspace        |                           0x00000000  TASK_SIZE
-  +------------------+                           0x40000000
-  +------------------+
-  | Page table       |  XCHAL_PAGE_TABLE_VADDR   0x80000000  XCHAL_PAGE_TABLE_SIZE
-  +------------------+
-  | KASAN shadow map |  KASAN_SHADOW_START       0x80400000  KASAN_SHADOW_SIZE
-  +------------------+                           0x8e400000
-  +------------------+
-  | VMALLOC area     |  VMALLOC_START            0x90000000  128MB - 64KB
-  +------------------+  VMALLOC_END
-  +------------------+
-  | Cache aliasing   |  TLBTEMP_BASE_1           0x98000000  DCACHE_WAY_SIZE
-  | remap area 1     |
-  +------------------+
-  | Cache aliasing   |  TLBTEMP_BASE_2                       DCACHE_WAY_SIZE
-  | remap area 2     |
-  +------------------+
-  +------------------+
-  | KMAP area        |  PKMAP_BASE                           PTRS_PER_PTE *
-  |                  |                                       DCACHE_N_COLORS *
-  |                  |                                       PAGE_SIZE
-  |                  |                                       (4MB * DCACHE_N_COLORS)
-  +------------------+
-  | Atomic KMAP area |  FIXADDR_START                        KM_TYPE_NR *
-  |                  |                                       NR_CPUS *
-  |                  |                                       DCACHE_N_COLORS *
-  |                  |                                       PAGE_SIZE
-  +------------------+  FIXADDR_TOP              0x9ffff000
-  +------------------+
-  | Cached KSEG      |  XCHAL_KSEG_CACHED_VADDR  0xa0000000  512MB
-  +------------------+
-  | Uncached KSEG    |  XCHAL_KSEG_BYPASS_VADDR  0xc0000000  512MB
-  +------------------+
-  | Cached KIO       |  XCHAL_KIO_CACHED_VADDR   0xe0000000  256MB
-  +------------------+
-  | Uncached KIO     |  XCHAL_KIO_BYPASS_VADDR   0xf0000000  256MB
-  +------------------+