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riscv: Add support for floating point

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This change adds full shared floating point support for the RISCV
architecture with minimal impact on threads with floating point
support not enabled.

Signed-off-by: Corey Wharton <coreyw7@fb.com>
This commit is contained in:
Corey Wharton 2020-03-11 18:15:29 -07:00 • committed by Andrew Boie
commit 58232d58e0
14 changed files with 667 additions and 18 deletions
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81
arch/riscv/core/thread.c
View file

@ -8,9 +8,9 @@
#include <ksched.h>
void z_thread_entry_wrapper(k_thread_entry_t thread,
void *arg1,
void *arg2,
void *arg3);
void *arg1,
void *arg2,
void *arg3);
void arch_new_thread(struct k_thread *thread, k_thread_stack_t *stack,
size_t stack_size, k_thread_entry_t thread_func,
@ -25,8 +25,8 @@ void arch_new_thread(struct k_thread *thread, k_thread_stack_t *stack,
/* Initial stack frame for thread */
stack_init = (struct __esf *)
Z_STACK_PTR_ALIGN(stack_memory +
stack_size - sizeof(struct __esf));
Z_STACK_PTR_ALIGN(stack_memory +
stack_size - sizeof(struct __esf));
/* Setup the initial stack frame */
stack_init->a0 = (ulong_t)thread_func;
@ -57,7 +57,78 @@ void arch_new_thread(struct k_thread *thread, k_thread_stack_t *stack,
* thread stack.
*/
stack_init->mstatus = MSTATUS_DEF_RESTORE;
#if defined(CONFIG_FLOAT) && defined(CONFIG_FP_SHARING)
if ((thread->base.user_options & K_FP_REGS) != 0) {
stack_init->mstatus |= MSTATUS_FS_INIT;
}
stack_init->fp_state = 0;
#endif
stack_init->mepc = (ulong_t)z_thread_entry_wrapper;
thread->callee_saved.sp = (ulong_t)stack_init;
}
#if defined(CONFIG_FLOAT) && defined(CONFIG_FP_SHARING)
int arch_float_disable(struct k_thread *thread)
{
unsigned int key;
if (thread != _current) {
return -EINVAL;
}
if (arch_is_in_isr()) {
return -EINVAL;
}
/* Ensure a preemptive context switch does not occur */
key = irq_lock();
/* Disable all floating point capabilities for the thread */
thread->base.user_options &= ~K_FP_REGS;
/* Clear the FS bits to disable the FPU. */
__asm__ volatile (
"mv t0, %0\n"
"csrrc x0, mstatus, t0\n"
:
: "r" (MSTATUS_FS_MASK)
);
irq_unlock(key);
return 0;
}
int arch_float_enable(struct k_thread *thread)
{
unsigned int key;
if (thread != _current) {
return -EINVAL;
}
if (arch_is_in_isr()) {
return -EINVAL;
}
/* Ensure a preemptive context switch does not occur */
key = irq_lock();
/* Enable all floating point capabilities for the thread. */
thread->base.user_options |= K_FP_REGS;
/* Set the FS bits to Initial to enable the FPU. */
__asm__ volatile (
"mv t0, %0\n"
"csrrs x0, mstatus, t0\n"
:
: "r" (MSTATUS_FS_INIT)
);
irq_unlock(key);
return 0;
}
#endif /* CONFIG_FLOAT && CONFIG_FP_SHARING */