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arch: arm: aarch32: clear CPACR for every CPU that has a FPU

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Upon reset, the Co-Processor Access Control Register is, normally,
0x00000000. However, it might be left un-cleared by firmware running
before Zephyr boot.
This restores the register back to reset value, even if CONFIG_FLOAT
is not set.
Clearing before setting supports switching between Full access
and Privileged access only.

Refactor enable_floating_point to support initialize
floating point registers for every CPU that has a FPU.

Signed-off-by: Luuk Bosma <l.bosma@interay.com>
This commit is contained in:
Luuk Bosma 2020-02-27 08:26:08 +01:00 • committed by Johan Hedberg
commit cc21aba55f
1 changed files with 16 additions and 9 deletions
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25
arch/arm/core/aarch32/prep_c.c
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@ -76,11 +76,18 @@ void __weak relocate_vector_table(void)
#endif /* CONFIG_CPU_CORTEX_M_HAS_VTOR */ #endif /* CONFIG_CPU_CORTEX_M_HAS_VTOR */
#ifdef CONFIG_FLOAT #if defined(CONFIG_CPU_HAS_FPU)
static inline void enable_floating_point(void) static inline void z_arm_floating_point_init(void)
{ {
/* /*
* Upon reset, the Co-Processor Access Control Register is 0x00000000. * Upon reset, the Co-Processor Access Control Register is, normally,
* 0x00000000. However, it might be left un-cleared by firmware running
* before Zephyr boot.
*/
SCB->CPACR &= (~(CPACR_CP10_Msk | CPACR_CP11_Msk));
#if defined(CONFIG_FLOAT)
/*
* Enable CP10 and CP11 Co-Processors to enable access to floating * Enable CP10 and CP11 Co-Processors to enable access to floating
* point registers. * point registers.
*/ */
@ -135,12 +142,10 @@ static inline void enable_floating_point(void)
* will be activated (FPCA bit on the CONTROL register) in the presence * will be activated (FPCA bit on the CONTROL register) in the presence
* of floating point instructions. * of floating point instructions.
*/ */
#endif /* CONFIG_FLOAT */
} }
#else #endif /* CONFIG_CPU_HAS_FPU */
static inline void enable_floating_point(void)
{
}
#endif
extern FUNC_NORETURN void z_cstart(void); extern FUNC_NORETURN void z_cstart(void);
/** /**
@ -154,7 +159,9 @@ extern FUNC_NORETURN void z_cstart(void);
void z_arm_prep_c(void) void z_arm_prep_c(void)
{ {
relocate_vector_table(); relocate_vector_table();
enable_floating_point(); #if defined(CONFIG_CPU_HAS_FPU)
z_arm_floating_point_init();
#endif
z_bss_zero(); z_bss_zero();
z_data_copy(); z_data_copy();
#if defined(CONFIG_ARMV7_R) && defined(CONFIG_INIT_STACKS) #if defined(CONFIG_ARMV7_R) && defined(CONFIG_INIT_STACKS)