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Rework RISC-V portASM.S to make it easier to add in chip specific RISC-V extensions and accommodate chips that don't include the CLINT.

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pull/4/head
Richard Barry 6 years ago
parent 7cc42b2ab6
commit 101806906d
2 changed files with 185 additions and 66 deletions
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74
FreeRTOS/Source/portable/GCC/RISC-V-RV32/CLINT/freertos_risc_v_port_specific_extensions.h
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@ -0,0 +1,74 @@
/*
* FreeRTOS Kernel V10.1.1
* Copyright (C) 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of
* this software and associated documentation files (the "Software"), to deal in
* the Software without restriction, including without limitation the rights to
* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
* the Software, and t
o permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
* http://www.FreeRTOS.org
* http://aws.amazon.com/freertos
*
* 1 tab == 4 spaces!
*/
/*
* The FreeRTOS kernel's RISC-V port is split between the the code that is
* common across all currently supported RISC-V chips (implementations of the
* RISC-V ISA), and code which tailors the port to a specific RISC-V chip:
*
* + The code that is common to all RISC-V chips is implemented in
* FreeRTOS\Source\portable\GCC\RISC-V-RV32\portASM.S. There is only one
* portASM.S file because the same file is used no matter which RISC-V chip is
* in use.
*
* + The code that tailors the kernel's RISC-V port to a specific RISC-V
* chip is implemented in freertos_risc_v_port_specific_extensions.h. There
* is one freertos_risc_v_port_specific_extensions.h that can be used with any
* RISC-V chip that both includes a standard CLINT and does not add to the
* base set of RISC-V registers. There are additional
* freertos_risc_v_port_specific_extensions.h files for RISC-V implementations
* that do not include a standard CLINT or do add to the base set of RISC-V
* regiters.
*
* CARE MUST BE TAKEN TO INCLDUE THE CORRECT
* freertos_risc_v_port_specific_extensions.h HEADER FILE FOR THE CHIP
* IN USE. To include the correct freertos_risc_v_port_specific_extensions.h
* header file ensure the path to the correct header file is in the assembler's
* include path.
*
* This freertos_risc_v_port_specific_extensions.h is for use on RISC-V chips
* that include a standard CLINT and do not add to the base set of RISC-V
* registers.
*
*/
#ifndef __FREERTOS_RISC_V_EXTENSIONS_H__
#define __FREERTOS_RISC_V_EXTENSIONS_H__
.macro portSAVE_ADDITIONAL_REGISTERS
/* This file is for use with chips that do not add to the standard RISC-V
* register set, so there is nothing to do here. */
.endm
.macro portRESTORE_ADDITIONAL_REGISTERS
/* This file is for use with chips that do not add to the standard RISC-V
* register set, so there is nothing to do here. */
.endm
#endif /* __FREERTOS_RISC_V_EXTENSIONS_H__ */

71
FreeRTOS/Source/portable/GCC/RISC-V-RV32/portASM.S
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@ -27,6 +27,38 @@
* 1 tab == 4 spaces!
*/
/*
* The FreeRTOS kernel's RISC-V port is split between the the code that is
* common across all currently supported RISC-V chips (implementations of the
* RISC-V ISA), and code which tailors the port to a specific RISC-V chip:
*
* + The code that is common to all RISC-V chips is implemented in
* FreeRTOS\Source\portable\GCC\RISC-V-RV32\portASM.S. There is only one
* portASM.S file because the same file is used no matter which RISC-V chip is
* in use.
*
* + The code that tailors the kernel's RISC-V port to a specific RISC-V
* chip is implemented in freertos_risc_v_port_specific_extensions.h. There
* is one freertos_risc_v_port_specific_extensions.h that can be used with any
* RISC-V chip that both includes a standard CLINT and does not add to the
* base set of RISC-V registers. There are additional
* freertos_risc_v_port_specific_extensions.h files for RISC-V implementations
* that do not include a standard CLINT or do add to the base set of RISC-V
* regiters.
*
* CARE MUST BE TAKEN TO INCLDUE THE CORRECT
* freertos_risc_v_port_specific_extensions.h HEADER FILE FOR THE CHIP
* IN USE. To include the correct freertos_risc_v_port_specific_extensions.h
* header file ensure the path to the correct header file is in the assembler's
* include path.
*
* This freertos_risc_v_port_specific_extensions.h is for use on RISC-V chips
* that include a standard CLINT and do not add to the base set of RISC-V
* registers.
*
*/
#include "freertos_risc_v_port_specific_extensions.h"
#if __riscv_xlen == 64
#error Not implemented yet - change lw to ld, and sw to sd.
#define WORD_SIZE 8
@ -86,6 +118,8 @@ vPortTrapHandler:
sw x30, 27 * WORD_SIZE( sp )
sw x31, 28 * WORD_SIZE( sp )
portSAVE_ADDITIONAL_REGISTERS /* Defined in freertos_risc_v_port_specific_extensions.h to save any registers unique to the RISC-V implementation. */
csrr t0, mstatus /* Required for MPIE bit. */
sw t0, 29 * WORD_SIZE( sp )
@ -95,21 +129,15 @@ vPortTrapHandler:
csrr a0, mcause
csrr a1, mepc
test_if_environment_call:
li t0, 11 /* 11 == environment call when using qemu. */
bne a0, t0, test_if_timer
addi a1, a1, 4 /* Synchronous so return to the instruction after the environment call. */
sw a1, 0( sp ) /* Save updated exception return address. */
lw sp, xISRStackTop /* Switch to ISR stack before function call. */
jal vTaskSwitchContext
j processed_source
test_if_timer:
test_if_asynchronous:
srli a2, a0, 0x1f /* MSB of mcause is 1 if handing an asynchronous interrupt - shift to LSB to clear other bits. */
beq a2, x0, handle_synchronous /* Branch past interrupt handing if not asynchronous. */
sw a1, 0( sp ) /* Asynch so save unmodified exception return address. */
handle_asynchronous:
test_if_mtimer:
lui t0, 0x80000
addi t1,t0, 7 /* 0x80000007 == machine timer interrupt. */
addi t1, t0, 7 /* 0x80000007 == machine timer interrupt. */
bne a0, t1, test_if_external_interrupt
lw t0, pullMachineTimerCompareRegister /* Load address of compare register into t0. */
@ -132,14 +160,29 @@ test_if_timer:
test_if_external_interrupt:
addi t1, t1, 4 /* 0x80000007 + 4 = 0x8000000b == Machine external interrupt. */
bne a0, t1, is_exception /* Only thing left it can be. */
bne a0, t1, as_yet_unhandled /* Something as yet unhandled. */
jal vPortHandleInterrupt
j processed_source
handle_synchronous:
addi a1, a1, 4 /* Synchronous so updated exception return address to the instruction after the instruction that generated the exeption. */
sw a1, 0( sp ) /* Save updated exception return address. */
test_if_environment_call:
li t0, 11 /* 11 == environment call. */
bne a0, t0, is_exception /* Not an M environment call, so some other exception. */
lw sp, xISRStackTop /* Switch to ISR stack before function call. */
jal vTaskSwitchContext
j processed_source
is_exception:
ebreak
j is_exception
as_yet_unhandled:
ebreak
j as_yet_unhandled
processed_source:
lw sp, pxCurrentTCB /* Load pxCurrentTCB. */
lw sp, 0( sp ) /* Read sp from first TCB member. */
@ -152,6 +195,8 @@ processed_source:
lw t0, 29 * WORD_SIZE( sp )
csrw mstatus, t0 /* Required for MPIE bit. */
portRESTORE_ADDITIONAL_REGISTERS /* Defined in freertos_risc_v_port_specific_extensions.h to restore any registers unique to the RISC-V implementation. */
lw x1, 1 * WORD_SIZE( sp )
lw x5, 2 * WORD_SIZE( sp ) /* t0 */
lw x6, 3 * WORD_SIZE( sp ) /* t1 */

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