1;/***************************************************************************
2; * Copyright (c) 2024 Microsoft Corporation
3; *
4; * This program and the accompanying materials are made available under the
5; * terms of the MIT License which is available at
6; * https://opensource.org/licenses/MIT.
7; *
8; * SPDX-License-Identifier: MIT
9; **************************************************************************/
10;
11;
12;/**************************************************************************/
13;/**************************************************************************/
14;/**                                                                       */
15;/** ThreadX Component                                                     */
16;/**                                                                       */
17;/**   Thread                                                              */
18;/**                                                                       */
19;/**************************************************************************/
20;/**************************************************************************/
21;
22;
23;#define TX_SOURCE_CODE
24;
25;
26;/* Include necessary system files.  */
27;
28;#include "tx_api.h"
29;#include "tx_thread.h"
30;
31;
32FIQ_DISABLE     EQU     0x40                    ; FIQ disable bit
33MODE_MASK       EQU     0x1F                    ; Mode mask
34SYS_MODE_BITS   EQU     0x1F                    ; System mode bits
35;
36;
37        AREA ||.text||, CODE, READONLY
38;/**************************************************************************/
39;/*                                                                        */
40;/*  FUNCTION                                               RELEASE        */
41;/*                                                                        */
42;/*    _tx_thread_fiq_nesting_start                        ARM11/AC5       */
43;/*                                                            6.1         */
44;/*  AUTHOR                                                                */
45;/*                                                                        */
46;/*    William E. Lamie, Microsoft Corporation                             */
47;/*                                                                        */
48;/*  DESCRIPTION                                                           */
49;/*                                                                        */
50;/*    This function is called by the application from FIQ mode after      */
51;/*    _tx_thread_fiq_context_save has been called and switches the FIQ    */
52;/*    processing to the system mode so nested FIQ interrupt processing    */
53;/*    is possible (system mode has its own "lr" register).  Note that     */
54;/*    this function assumes that the system mode stack pointer was setup  */
55;/*    during low-level initialization (tx_initialize_low_level.s).        */
56;/*                                                                        */
57;/*    This function returns with FIQ interrupts enabled.                  */
58;/*                                                                        */
59;/*  INPUT                                                                 */
60;/*                                                                        */
61;/*    None                                                                */
62;/*                                                                        */
63;/*  OUTPUT                                                                */
64;/*                                                                        */
65;/*    None                                                                */
66;/*                                                                        */
67;/*  CALLS                                                                 */
68;/*                                                                        */
69;/*    None                                                                */
70;/*                                                                        */
71;/*  CALLED BY                                                             */
72;/*                                                                        */
73;/*    ISRs                                                                */
74;/*                                                                        */
75;/*  RELEASE HISTORY                                                       */
76;/*                                                                        */
77;/*    DATE              NAME                      DESCRIPTION             */
78;/*                                                                        */
79;/*  09-30-2020     William E. Lamie         Initial Version 6.1           */
80;/*                                                                        */
81;/**************************************************************************/
82;VOID   _tx_thread_fiq_nesting_start(VOID)
83;{
84    EXPORT  _tx_thread_fiq_nesting_start
85_tx_thread_fiq_nesting_start
86    MOV     r3,lr                               ; Save ISR return address
87    MRS     r0, CPSR                            ; Pickup the CPSR
88    BIC     r0, r0, #MODE_MASK                  ; Clear the mode bits
89    ORR     r0, r0, #SYS_MODE_BITS              ; Build system mode CPSR
90    MSR     CPSR_cxsf, r0                       ; Enter system mode
91    STMDB   sp!, {r1, lr}                       ; Push the system mode lr on the system mode stack
92                                                ;   and push r1 just to keep 8-byte alignment
93    BIC     r0, r0, #FIQ_DISABLE                ; Build enable FIQ CPSR
94    MSR     CPSR_cxsf, r0                       ; Enter system mode
95    IF  {INTER} = {TRUE}
96    BX      r3                                  ; Return to caller
97    ELSE
98    MOV     pc, r3                              ; Return to caller
99    ENDIF
100;}
101;
102    END
103
104