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#ifdef TX_INCLUDE_USER_DEFINE_FILE
22#include "tx_user.h"
23#endif
24
25FIQ_DISABLE     =       0x40                    @ FIQ disable bit
26MODE_MASK       =       0x1F                    @ Mode mask
27SYS_MODE_BITS   =       0x1F                    @ System mode bits
28@
29@
30@/* No 16-bit Thumb mode veneer code is needed for _tx_thread_fiq_nesting_start
31@   since it will never be called 16-bit mode.  */
32@
33    .arm
34    .text
35    .align 2
36@/**************************************************************************/
37@/*                                                                        */
38@/*  FUNCTION                                               RELEASE        */
39@/*                                                                        */
40@/*    _tx_thread_fiq_nesting_start                        ARM11/GNU       */
41@/*                                                            6.2.1       */
42@/*  AUTHOR                                                                */
43@/*                                                                        */
44@/*    William E. Lamie, Microsoft Corporation                             */
45@/*                                                                        */
46@/*  DESCRIPTION                                                           */
47@/*                                                                        */
48@/*    This function is called by the application from FIQ mode after      */
49@/*    _tx_thread_fiq_context_save has been called and switches the FIQ    */
50@/*    processing to the system mode so nested FIQ interrupt processing    */
51@/*    is possible (system mode has its own "lr" register).  Note that     */
52@/*    this function assumes that the system mode stack pointer was setup  */
53@/*    during low-level initialization (tx_initialize_low_level.s).        */
54@/*                                                                        */
55@/*    This function returns with FIQ interrupts enabled.                  */
56@/*                                                                        */
57@/*  INPUT                                                                 */
58@/*                                                                        */
59@/*    None                                                                */
60@/*                                                                        */
61@/*  OUTPUT                                                                */
62@/*                                                                        */
63@/*    None                                                                */
64@/*                                                                        */
65@/*  CALLS                                                                 */
66@/*                                                                        */
67@/*    None                                                                */
68@/*                                                                        */
69@/*  CALLED BY                                                             */
70@/*                                                                        */
71@/*    ISRs                                                                */
72@/*                                                                        */
73@/*  RELEASE HISTORY                                                       */
74@/*                                                                        */
75@/*    DATE              NAME                      DESCRIPTION             */
76@/*                                                                        */
77@/*  09-30-2020     William E. Lamie         Initial Version 6.1           */
78@/*  03-08-2023     Cindy Deng               Modified comment(s), added    */
79@/*                                            #include tx_user.h,         */
80@/*                                            resulting in version 6.2.1  */
81@/*                                                                        */
82@/**************************************************************************/
83@VOID   _tx_thread_fiq_nesting_start(VOID)
84@{
85    .global  _tx_thread_fiq_nesting_start
86    .type    _tx_thread_fiq_nesting_start,function
87_tx_thread_fiq_nesting_start:
88    MOV     r3,lr                               @ Save ISR return address
89    MRS     r0, CPSR                            @ Pickup the CPSR
90    BIC     r0, r0, #MODE_MASK                  @ Clear the mode bits
91    ORR     r0, r0, #SYS_MODE_BITS              @ Build system mode CPSR
92    MSR     CPSR_cxsf, r0                       @ Enter system mode
93    STMDB   sp!, {r1, lr}                       @ Push the system mode lr on the system mode stack
94                                                @   and push r1 just to keep 8-byte alignment
95    BIC     r0, r0, #FIQ_DISABLE                @ Build enable FIQ CPSR
96    MSR     CPSR_cxsf, r0                       @ Enter system mode
97    MOV     pc, r3                              @ Return to caller
98@}
99
100