From b13e2698bb1dc0778bb4b5078c03a34097108497 Mon Sep 17 00:00:00 2001 From: Jeff Tenney Date: Wed, 26 Jul 2023 21:52:13 -0700 Subject: [PATCH] Work around SysTick bug for QEMU ARMv8-M (#724) * Set SysTick CLKSOURCE bit before enabling SysTick * Use portNVIC_SYSTICK_CLK_BIT_CONFIG The workaround now uses portNVIC_SYSTICK_CLK_BIT_CONFIG instead of portNVIC_SYSTICK_CLK_BIT, which saves us from having to explain in the comments why it's OK to temporarily set the CLKSOURCE bit even if the user's FreeRTOS configuration clears the CLKSOURCE bit. Using portNVIC_SYSTICK_CLK_BIT_CONFIG here still correctly prevents the firmware from triggering the QEMU bug. --- portable/ARMv8M/non_secure/port.c | 11 +++++++++-- portable/GCC/ARM_CM23/non_secure/port.c | 11 +++++++++-- portable/GCC/ARM_CM23_NTZ/non_secure/port.c | 11 +++++++++-- portable/GCC/ARM_CM33/non_secure/port.c | 11 +++++++++-- portable/GCC/ARM_CM33_NTZ/non_secure/port.c | 11 +++++++++-- portable/GCC/ARM_CM35P/non_secure/port.c | 11 +++++++++-- portable/GCC/ARM_CM35P_NTZ/non_secure/port.c | 11 +++++++++-- portable/GCC/ARM_CM55/non_secure/port.c | 11 +++++++++-- portable/GCC/ARM_CM55_NTZ/non_secure/port.c | 11 +++++++++-- portable/GCC/ARM_CM85/non_secure/port.c | 11 +++++++++-- portable/GCC/ARM_CM85_NTZ/non_secure/port.c | 11 +++++++++-- portable/IAR/ARM_CM23/non_secure/port.c | 11 +++++++++-- portable/IAR/ARM_CM23_NTZ/non_secure/port.c | 11 +++++++++-- portable/IAR/ARM_CM33/non_secure/port.c | 11 +++++++++-- portable/IAR/ARM_CM33_NTZ/non_secure/port.c | 11 +++++++++-- portable/IAR/ARM_CM35P/non_secure/port.c | 11 +++++++++-- portable/IAR/ARM_CM35P_NTZ/non_secure/port.c | 11 +++++++++-- portable/IAR/ARM_CM55/non_secure/port.c | 11 +++++++++-- portable/IAR/ARM_CM55_NTZ/non_secure/port.c | 11 +++++++++-- portable/IAR/ARM_CM85/non_secure/port.c | 11 +++++++++-- portable/IAR/ARM_CM85_NTZ/non_secure/port.c | 11 +++++++++-- 21 files changed, 189 insertions(+), 42 deletions(-) diff --git a/portable/ARMv8M/non_secure/port.c b/portable/ARMv8M/non_secure/port.c index 04901015f..e027b21e1 100644 --- a/portable/ARMv8M/non_secure/port.c +++ b/portable/ARMv8M/non_secure/port.c @@ -754,8 +754,15 @@ __attribute__( ( weak ) ) void vPortSetupTimerInterrupt( void ) /* PRIVILEGED_FU } #endif /* configUSE_TICKLESS_IDLE */ - /* Stop and reset the SysTick. */ - portNVIC_SYSTICK_CTRL_REG = 0UL; + /* Stop and reset SysTick. + * + * QEMU versions older than 7.0.0 contain a bug which causes an error if we + * enable SysTick without first selecting a valid clock source. We trigger + * the bug if we change clock sources from a clock with a zero clock period + * to one with a nonzero clock period and enable Systick at the same time. + * So we configure the CLKSOURCE bit here, prior to setting the ENABLE bit. + * This workaround avoids the bug in QEMU versions older than 7.0.0. */ + portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT_CONFIG; portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL; /* Configure SysTick to interrupt at the requested rate. */ diff --git a/portable/GCC/ARM_CM23/non_secure/port.c b/portable/GCC/ARM_CM23/non_secure/port.c index 04901015f..e027b21e1 100644 --- a/portable/GCC/ARM_CM23/non_secure/port.c +++ b/portable/GCC/ARM_CM23/non_secure/port.c @@ -754,8 +754,15 @@ __attribute__( ( weak ) ) void vPortSetupTimerInterrupt( void ) /* PRIVILEGED_FU } #endif /* configUSE_TICKLESS_IDLE */ - /* Stop and reset the SysTick. */ - portNVIC_SYSTICK_CTRL_REG = 0UL; + /* Stop and reset SysTick. + * + * QEMU versions older than 7.0.0 contain a bug which causes an error if we + * enable SysTick without first selecting a valid clock source. We trigger + * the bug if we change clock sources from a clock with a zero clock period + * to one with a nonzero clock period and enable Systick at the same time. + * So we configure the CLKSOURCE bit here, prior to setting the ENABLE bit. + * This workaround avoids the bug in QEMU versions older than 7.0.0. */ + portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT_CONFIG; portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL; /* Configure SysTick to interrupt at the requested rate. */ diff --git a/portable/GCC/ARM_CM23_NTZ/non_secure/port.c b/portable/GCC/ARM_CM23_NTZ/non_secure/port.c index 04901015f..e027b21e1 100644 --- a/portable/GCC/ARM_CM23_NTZ/non_secure/port.c +++ b/portable/GCC/ARM_CM23_NTZ/non_secure/port.c @@ -754,8 +754,15 @@ __attribute__( ( weak ) ) void vPortSetupTimerInterrupt( void ) /* PRIVILEGED_FU } #endif /* configUSE_TICKLESS_IDLE */ - /* Stop and reset the SysTick. */ - portNVIC_SYSTICK_CTRL_REG = 0UL; + /* Stop and reset SysTick. + * + * QEMU versions older than 7.0.0 contain a bug which causes an error if we + * enable SysTick without first selecting a valid clock source. We trigger + * the bug if we change clock sources from a clock with a zero clock period + * to one with a nonzero clock period and enable Systick at the same time. + * So we configure the CLKSOURCE bit here, prior to setting the ENABLE bit. + * This workaround avoids the bug in QEMU versions older than 7.0.0. */ + portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT_CONFIG; portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL; /* Configure SysTick to interrupt at the requested rate. */ diff --git a/portable/GCC/ARM_CM33/non_secure/port.c b/portable/GCC/ARM_CM33/non_secure/port.c index 04901015f..e027b21e1 100644 --- a/portable/GCC/ARM_CM33/non_secure/port.c +++ b/portable/GCC/ARM_CM33/non_secure/port.c @@ -754,8 +754,15 @@ __attribute__( ( weak ) ) void vPortSetupTimerInterrupt( void ) /* PRIVILEGED_FU } #endif /* configUSE_TICKLESS_IDLE */ - /* Stop and reset the SysTick. */ - portNVIC_SYSTICK_CTRL_REG = 0UL; + /* Stop and reset SysTick. + * + * QEMU versions older than 7.0.0 contain a bug which causes an error if we + * enable SysTick without first selecting a valid clock source. We trigger + * the bug if we change clock sources from a clock with a zero clock period + * to one with a nonzero clock period and enable Systick at the same time. + * So we configure the CLKSOURCE bit here, prior to setting the ENABLE bit. + * This workaround avoids the bug in QEMU versions older than 7.0.0. */ + portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT_CONFIG; portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL; /* Configure SysTick to interrupt at the requested rate. */ diff --git a/portable/GCC/ARM_CM33_NTZ/non_secure/port.c b/portable/GCC/ARM_CM33_NTZ/non_secure/port.c index 04901015f..e027b21e1 100644 --- a/portable/GCC/ARM_CM33_NTZ/non_secure/port.c +++ b/portable/GCC/ARM_CM33_NTZ/non_secure/port.c @@ -754,8 +754,15 @@ __attribute__( ( weak ) ) void vPortSetupTimerInterrupt( void ) /* PRIVILEGED_FU } #endif /* configUSE_TICKLESS_IDLE */ - /* Stop and reset the SysTick. */ - portNVIC_SYSTICK_CTRL_REG = 0UL; + /* Stop and reset SysTick. + * + * QEMU versions older than 7.0.0 contain a bug which causes an error if we + * enable SysTick without first selecting a valid clock source. We trigger + * the bug if we change clock sources from a clock with a zero clock period + * to one with a nonzero clock period and enable Systick at the same time. + * So we configure the CLKSOURCE bit here, prior to setting the ENABLE bit. + * This workaround avoids the bug in QEMU versions older than 7.0.0. */ + portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT_CONFIG; portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL; /* Configure SysTick to interrupt at the requested rate. */ diff --git a/portable/GCC/ARM_CM35P/non_secure/port.c b/portable/GCC/ARM_CM35P/non_secure/port.c index 04901015f..e027b21e1 100644 --- a/portable/GCC/ARM_CM35P/non_secure/port.c +++ b/portable/GCC/ARM_CM35P/non_secure/port.c @@ -754,8 +754,15 @@ __attribute__( ( weak ) ) void vPortSetupTimerInterrupt( void ) /* PRIVILEGED_FU } #endif /* configUSE_TICKLESS_IDLE */ - /* Stop and reset the SysTick. */ - portNVIC_SYSTICK_CTRL_REG = 0UL; + /* Stop and reset SysTick. + * + * QEMU versions older than 7.0.0 contain a bug which causes an error if we + * enable SysTick without first selecting a valid clock source. We trigger + * the bug if we change clock sources from a clock with a zero clock period + * to one with a nonzero clock period and enable Systick at the same time. + * So we configure the CLKSOURCE bit here, prior to setting the ENABLE bit. + * This workaround avoids the bug in QEMU versions older than 7.0.0. */ + portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT_CONFIG; portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL; /* Configure SysTick to interrupt at the requested rate. */ diff --git a/portable/GCC/ARM_CM35P_NTZ/non_secure/port.c b/portable/GCC/ARM_CM35P_NTZ/non_secure/port.c index 04901015f..e027b21e1 100644 --- a/portable/GCC/ARM_CM35P_NTZ/non_secure/port.c +++ b/portable/GCC/ARM_CM35P_NTZ/non_secure/port.c @@ -754,8 +754,15 @@ __attribute__( ( weak ) ) void vPortSetupTimerInterrupt( void ) /* PRIVILEGED_FU } #endif /* configUSE_TICKLESS_IDLE */ - /* Stop and reset the SysTick. */ - portNVIC_SYSTICK_CTRL_REG = 0UL; + /* Stop and reset SysTick. + * + * QEMU versions older than 7.0.0 contain a bug which causes an error if we + * enable SysTick without first selecting a valid clock source. We trigger + * the bug if we change clock sources from a clock with a zero clock period + * to one with a nonzero clock period and enable Systick at the same time. + * So we configure the CLKSOURCE bit here, prior to setting the ENABLE bit. + * This workaround avoids the bug in QEMU versions older than 7.0.0. */ + portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT_CONFIG; portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL; /* Configure SysTick to interrupt at the requested rate. */ diff --git a/portable/GCC/ARM_CM55/non_secure/port.c b/portable/GCC/ARM_CM55/non_secure/port.c index 04901015f..e027b21e1 100644 --- a/portable/GCC/ARM_CM55/non_secure/port.c +++ b/portable/GCC/ARM_CM55/non_secure/port.c @@ -754,8 +754,15 @@ __attribute__( ( weak ) ) void vPortSetupTimerInterrupt( void ) /* PRIVILEGED_FU } #endif /* configUSE_TICKLESS_IDLE */ - /* Stop and reset the SysTick. */ - portNVIC_SYSTICK_CTRL_REG = 0UL; + /* Stop and reset SysTick. + * + * QEMU versions older than 7.0.0 contain a bug which causes an error if we + * enable SysTick without first selecting a valid clock source. We trigger + * the bug if we change clock sources from a clock with a zero clock period + * to one with a nonzero clock period and enable Systick at the same time. + * So we configure the CLKSOURCE bit here, prior to setting the ENABLE bit. + * This workaround avoids the bug in QEMU versions older than 7.0.0. */ + portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT_CONFIG; portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL; /* Configure SysTick to interrupt at the requested rate. */ diff --git a/portable/GCC/ARM_CM55_NTZ/non_secure/port.c b/portable/GCC/ARM_CM55_NTZ/non_secure/port.c index 04901015f..e027b21e1 100644 --- a/portable/GCC/ARM_CM55_NTZ/non_secure/port.c +++ b/portable/GCC/ARM_CM55_NTZ/non_secure/port.c @@ -754,8 +754,15 @@ __attribute__( ( weak ) ) void vPortSetupTimerInterrupt( void ) /* PRIVILEGED_FU } #endif /* configUSE_TICKLESS_IDLE */ - /* Stop and reset the SysTick. */ - portNVIC_SYSTICK_CTRL_REG = 0UL; + /* Stop and reset SysTick. + * + * QEMU versions older than 7.0.0 contain a bug which causes an error if we + * enable SysTick without first selecting a valid clock source. We trigger + * the bug if we change clock sources from a clock with a zero clock period + * to one with a nonzero clock period and enable Systick at the same time. + * So we configure the CLKSOURCE bit here, prior to setting the ENABLE bit. + * This workaround avoids the bug in QEMU versions older than 7.0.0. */ + portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT_CONFIG; portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL; /* Configure SysTick to interrupt at the requested rate. */ diff --git a/portable/GCC/ARM_CM85/non_secure/port.c b/portable/GCC/ARM_CM85/non_secure/port.c index 04901015f..e027b21e1 100644 --- a/portable/GCC/ARM_CM85/non_secure/port.c +++ b/portable/GCC/ARM_CM85/non_secure/port.c @@ -754,8 +754,15 @@ __attribute__( ( weak ) ) void vPortSetupTimerInterrupt( void ) /* PRIVILEGED_FU } #endif /* configUSE_TICKLESS_IDLE */ - /* Stop and reset the SysTick. */ - portNVIC_SYSTICK_CTRL_REG = 0UL; + /* Stop and reset SysTick. + * + * QEMU versions older than 7.0.0 contain a bug which causes an error if we + * enable SysTick without first selecting a valid clock source. We trigger + * the bug if we change clock sources from a clock with a zero clock period + * to one with a nonzero clock period and enable Systick at the same time. + * So we configure the CLKSOURCE bit here, prior to setting the ENABLE bit. + * This workaround avoids the bug in QEMU versions older than 7.0.0. */ + portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT_CONFIG; portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL; /* Configure SysTick to interrupt at the requested rate. */ diff --git a/portable/GCC/ARM_CM85_NTZ/non_secure/port.c b/portable/GCC/ARM_CM85_NTZ/non_secure/port.c index 04901015f..e027b21e1 100644 --- a/portable/GCC/ARM_CM85_NTZ/non_secure/port.c +++ b/portable/GCC/ARM_CM85_NTZ/non_secure/port.c @@ -754,8 +754,15 @@ __attribute__( ( weak ) ) void vPortSetupTimerInterrupt( void ) /* PRIVILEGED_FU } #endif /* configUSE_TICKLESS_IDLE */ - /* Stop and reset the SysTick. */ - portNVIC_SYSTICK_CTRL_REG = 0UL; + /* Stop and reset SysTick. + * + * QEMU versions older than 7.0.0 contain a bug which causes an error if we + * enable SysTick without first selecting a valid clock source. We trigger + * the bug if we change clock sources from a clock with a zero clock period + * to one with a nonzero clock period and enable Systick at the same time. + * So we configure the CLKSOURCE bit here, prior to setting the ENABLE bit. + * This workaround avoids the bug in QEMU versions older than 7.0.0. */ + portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT_CONFIG; portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL; /* Configure SysTick to interrupt at the requested rate. */ diff --git a/portable/IAR/ARM_CM23/non_secure/port.c b/portable/IAR/ARM_CM23/non_secure/port.c index 04901015f..e027b21e1 100644 --- a/portable/IAR/ARM_CM23/non_secure/port.c +++ b/portable/IAR/ARM_CM23/non_secure/port.c @@ -754,8 +754,15 @@ __attribute__( ( weak ) ) void vPortSetupTimerInterrupt( void ) /* PRIVILEGED_FU } #endif /* configUSE_TICKLESS_IDLE */ - /* Stop and reset the SysTick. */ - portNVIC_SYSTICK_CTRL_REG = 0UL; + /* Stop and reset SysTick. + * + * QEMU versions older than 7.0.0 contain a bug which causes an error if we + * enable SysTick without first selecting a valid clock source. We trigger + * the bug if we change clock sources from a clock with a zero clock period + * to one with a nonzero clock period and enable Systick at the same time. + * So we configure the CLKSOURCE bit here, prior to setting the ENABLE bit. + * This workaround avoids the bug in QEMU versions older than 7.0.0. */ + portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT_CONFIG; portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL; /* Configure SysTick to interrupt at the requested rate. */ diff --git a/portable/IAR/ARM_CM23_NTZ/non_secure/port.c b/portable/IAR/ARM_CM23_NTZ/non_secure/port.c index 04901015f..e027b21e1 100644 --- a/portable/IAR/ARM_CM23_NTZ/non_secure/port.c +++ b/portable/IAR/ARM_CM23_NTZ/non_secure/port.c @@ -754,8 +754,15 @@ __attribute__( ( weak ) ) void vPortSetupTimerInterrupt( void ) /* PRIVILEGED_FU } #endif /* configUSE_TICKLESS_IDLE */ - /* Stop and reset the SysTick. */ - portNVIC_SYSTICK_CTRL_REG = 0UL; + /* Stop and reset SysTick. + * + * QEMU versions older than 7.0.0 contain a bug which causes an error if we + * enable SysTick without first selecting a valid clock source. We trigger + * the bug if we change clock sources from a clock with a zero clock period + * to one with a nonzero clock period and enable Systick at the same time. + * So we configure the CLKSOURCE bit here, prior to setting the ENABLE bit. + * This workaround avoids the bug in QEMU versions older than 7.0.0. */ + portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT_CONFIG; portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL; /* Configure SysTick to interrupt at the requested rate. */ diff --git a/portable/IAR/ARM_CM33/non_secure/port.c b/portable/IAR/ARM_CM33/non_secure/port.c index 04901015f..e027b21e1 100644 --- a/portable/IAR/ARM_CM33/non_secure/port.c +++ b/portable/IAR/ARM_CM33/non_secure/port.c @@ -754,8 +754,15 @@ __attribute__( ( weak ) ) void vPortSetupTimerInterrupt( void ) /* PRIVILEGED_FU } #endif /* configUSE_TICKLESS_IDLE */ - /* Stop and reset the SysTick. */ - portNVIC_SYSTICK_CTRL_REG = 0UL; + /* Stop and reset SysTick. + * + * QEMU versions older than 7.0.0 contain a bug which causes an error if we + * enable SysTick without first selecting a valid clock source. We trigger + * the bug if we change clock sources from a clock with a zero clock period + * to one with a nonzero clock period and enable Systick at the same time. + * So we configure the CLKSOURCE bit here, prior to setting the ENABLE bit. + * This workaround avoids the bug in QEMU versions older than 7.0.0. */ + portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT_CONFIG; portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL; /* Configure SysTick to interrupt at the requested rate. */ diff --git a/portable/IAR/ARM_CM33_NTZ/non_secure/port.c b/portable/IAR/ARM_CM33_NTZ/non_secure/port.c index 04901015f..e027b21e1 100644 --- a/portable/IAR/ARM_CM33_NTZ/non_secure/port.c +++ b/portable/IAR/ARM_CM33_NTZ/non_secure/port.c @@ -754,8 +754,15 @@ __attribute__( ( weak ) ) void vPortSetupTimerInterrupt( void ) /* PRIVILEGED_FU } #endif /* configUSE_TICKLESS_IDLE */ - /* Stop and reset the SysTick. */ - portNVIC_SYSTICK_CTRL_REG = 0UL; + /* Stop and reset SysTick. + * + * QEMU versions older than 7.0.0 contain a bug which causes an error if we + * enable SysTick without first selecting a valid clock source. We trigger + * the bug if we change clock sources from a clock with a zero clock period + * to one with a nonzero clock period and enable Systick at the same time. + * So we configure the CLKSOURCE bit here, prior to setting the ENABLE bit. + * This workaround avoids the bug in QEMU versions older than 7.0.0. */ + portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT_CONFIG; portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL; /* Configure SysTick to interrupt at the requested rate. */ diff --git a/portable/IAR/ARM_CM35P/non_secure/port.c b/portable/IAR/ARM_CM35P/non_secure/port.c index 04901015f..e027b21e1 100644 --- a/portable/IAR/ARM_CM35P/non_secure/port.c +++ b/portable/IAR/ARM_CM35P/non_secure/port.c @@ -754,8 +754,15 @@ __attribute__( ( weak ) ) void vPortSetupTimerInterrupt( void ) /* PRIVILEGED_FU } #endif /* configUSE_TICKLESS_IDLE */ - /* Stop and reset the SysTick. */ - portNVIC_SYSTICK_CTRL_REG = 0UL; + /* Stop and reset SysTick. + * + * QEMU versions older than 7.0.0 contain a bug which causes an error if we + * enable SysTick without first selecting a valid clock source. We trigger + * the bug if we change clock sources from a clock with a zero clock period + * to one with a nonzero clock period and enable Systick at the same time. + * So we configure the CLKSOURCE bit here, prior to setting the ENABLE bit. + * This workaround avoids the bug in QEMU versions older than 7.0.0. */ + portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT_CONFIG; portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL; /* Configure SysTick to interrupt at the requested rate. */ diff --git a/portable/IAR/ARM_CM35P_NTZ/non_secure/port.c b/portable/IAR/ARM_CM35P_NTZ/non_secure/port.c index 04901015f..e027b21e1 100644 --- a/portable/IAR/ARM_CM35P_NTZ/non_secure/port.c +++ b/portable/IAR/ARM_CM35P_NTZ/non_secure/port.c @@ -754,8 +754,15 @@ __attribute__( ( weak ) ) void vPortSetupTimerInterrupt( void ) /* PRIVILEGED_FU } #endif /* configUSE_TICKLESS_IDLE */ - /* Stop and reset the SysTick. */ - portNVIC_SYSTICK_CTRL_REG = 0UL; + /* Stop and reset SysTick. + * + * QEMU versions older than 7.0.0 contain a bug which causes an error if we + * enable SysTick without first selecting a valid clock source. We trigger + * the bug if we change clock sources from a clock with a zero clock period + * to one with a nonzero clock period and enable Systick at the same time. + * So we configure the CLKSOURCE bit here, prior to setting the ENABLE bit. + * This workaround avoids the bug in QEMU versions older than 7.0.0. */ + portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT_CONFIG; portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL; /* Configure SysTick to interrupt at the requested rate. */ diff --git a/portable/IAR/ARM_CM55/non_secure/port.c b/portable/IAR/ARM_CM55/non_secure/port.c index 04901015f..e027b21e1 100644 --- a/portable/IAR/ARM_CM55/non_secure/port.c +++ b/portable/IAR/ARM_CM55/non_secure/port.c @@ -754,8 +754,15 @@ __attribute__( ( weak ) ) void vPortSetupTimerInterrupt( void ) /* PRIVILEGED_FU } #endif /* configUSE_TICKLESS_IDLE */ - /* Stop and reset the SysTick. */ - portNVIC_SYSTICK_CTRL_REG = 0UL; + /* Stop and reset SysTick. + * + * QEMU versions older than 7.0.0 contain a bug which causes an error if we + * enable SysTick without first selecting a valid clock source. We trigger + * the bug if we change clock sources from a clock with a zero clock period + * to one with a nonzero clock period and enable Systick at the same time. + * So we configure the CLKSOURCE bit here, prior to setting the ENABLE bit. + * This workaround avoids the bug in QEMU versions older than 7.0.0. */ + portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT_CONFIG; portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL; /* Configure SysTick to interrupt at the requested rate. */ diff --git a/portable/IAR/ARM_CM55_NTZ/non_secure/port.c b/portable/IAR/ARM_CM55_NTZ/non_secure/port.c index 04901015f..e027b21e1 100644 --- a/portable/IAR/ARM_CM55_NTZ/non_secure/port.c +++ b/portable/IAR/ARM_CM55_NTZ/non_secure/port.c @@ -754,8 +754,15 @@ __attribute__( ( weak ) ) void vPortSetupTimerInterrupt( void ) /* PRIVILEGED_FU } #endif /* configUSE_TICKLESS_IDLE */ - /* Stop and reset the SysTick. */ - portNVIC_SYSTICK_CTRL_REG = 0UL; + /* Stop and reset SysTick. + * + * QEMU versions older than 7.0.0 contain a bug which causes an error if we + * enable SysTick without first selecting a valid clock source. We trigger + * the bug if we change clock sources from a clock with a zero clock period + * to one with a nonzero clock period and enable Systick at the same time. + * So we configure the CLKSOURCE bit here, prior to setting the ENABLE bit. + * This workaround avoids the bug in QEMU versions older than 7.0.0. */ + portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT_CONFIG; portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL; /* Configure SysTick to interrupt at the requested rate. */ diff --git a/portable/IAR/ARM_CM85/non_secure/port.c b/portable/IAR/ARM_CM85/non_secure/port.c index 04901015f..e027b21e1 100644 --- a/portable/IAR/ARM_CM85/non_secure/port.c +++ b/portable/IAR/ARM_CM85/non_secure/port.c @@ -754,8 +754,15 @@ __attribute__( ( weak ) ) void vPortSetupTimerInterrupt( void ) /* PRIVILEGED_FU } #endif /* configUSE_TICKLESS_IDLE */ - /* Stop and reset the SysTick. */ - portNVIC_SYSTICK_CTRL_REG = 0UL; + /* Stop and reset SysTick. + * + * QEMU versions older than 7.0.0 contain a bug which causes an error if we + * enable SysTick without first selecting a valid clock source. We trigger + * the bug if we change clock sources from a clock with a zero clock period + * to one with a nonzero clock period and enable Systick at the same time. + * So we configure the CLKSOURCE bit here, prior to setting the ENABLE bit. + * This workaround avoids the bug in QEMU versions older than 7.0.0. */ + portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT_CONFIG; portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL; /* Configure SysTick to interrupt at the requested rate. */ diff --git a/portable/IAR/ARM_CM85_NTZ/non_secure/port.c b/portable/IAR/ARM_CM85_NTZ/non_secure/port.c index 04901015f..e027b21e1 100644 --- a/portable/IAR/ARM_CM85_NTZ/non_secure/port.c +++ b/portable/IAR/ARM_CM85_NTZ/non_secure/port.c @@ -754,8 +754,15 @@ __attribute__( ( weak ) ) void vPortSetupTimerInterrupt( void ) /* PRIVILEGED_FU } #endif /* configUSE_TICKLESS_IDLE */ - /* Stop and reset the SysTick. */ - portNVIC_SYSTICK_CTRL_REG = 0UL; + /* Stop and reset SysTick. + * + * QEMU versions older than 7.0.0 contain a bug which causes an error if we + * enable SysTick without first selecting a valid clock source. We trigger + * the bug if we change clock sources from a clock with a zero clock period + * to one with a nonzero clock period and enable Systick at the same time. + * So we configure the CLKSOURCE bit here, prior to setting the ENABLE bit. + * This workaround avoids the bug in QEMU versions older than 7.0.0. */ + portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT_CONFIG; portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL; /* Configure SysTick to interrupt at the requested rate. */