cortexm_common: enable FPU on cortex-m4f

RIOT-OS · Jan 3, 2019 · 06f0c14 · 06f0c14
1 parent bc5e3e7
commit 06f0c14
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Showing 3 changed files with 34 additions and 30 deletions.
diff --git a/cpu/cortexm_common/thread_arch.c b/cpu/cortexm_common/thread_arch.c
@@ -148,22 +148,6 @@ char *thread_stack_init(thread_task_func_t task_func,
         *stk = ~((uint32_t)STACK_MARKER);
     }
 
-#if defined(CPU_ARCH_CORTEX_M4F) || (CPU_ARCH_CORTEX_M7)
-    /* TODO: fix FPU handling for Cortex-M4f */
-    /*
-    stk--;
-    *stk = (unsigned int) 0;
-    */
-
-    /* S0 - S15 */
-    /*
-    for (int i = 15; i >= 0; i--) {
-        stk--;
-        *stk = i;
-    }
-    */
-#endif
-
     /* ****************************** */
     /* Automatically popped registers */
     /* ****************************** */
@@ -299,7 +283,7 @@ void __attribute__((naked)) __attribute__((used)) isr_pendsv(void) {
     __asm__ volatile (
     /* PendSV handler entry point */
     /* save context by pushing unsaved registers to the stack */
-    /* {r0-r3,r12,LR,PC,xPSR} are saved automatically on exception entry */
+    /* {r0-r3,r12,LR,PC,xPSR,s0-s15,FPSCR} are saved automatically on exception entry */
     ".thumb_func                      \n"
     "mrs    r0, psp                   \n" /* get stack pointer from user mode */
 #if defined(CPU_ARCH_CORTEX_M0) || defined(CPU_ARCH_CORTEX_M0PLUS)
@@ -317,11 +301,13 @@ void __attribute__((naked)) __attribute__((used)) isr_pendsv(void) {
     "mov    r0, sp                    \n" /* switch back to the exception SP */
     "mov    sp, r12                   \n"
 #else
+#if (defined(CPU_ARCH_CORTEX_M4F) || defined(CPU_ARCH_CORTEX_M7)) && defined(MODULE_CORTEXM_FPU)
+    "tst    lr, #0x10                 \n"
+    "it     eq                        \n"
+    "vstmdbeq r0!, {s16-s31}          \n" /* save FPU registers if FPU is used */
+#endif
     "stmdb  r0!,{r4-r11}              \n" /* save regs */
     "stmdb  r0!,{lr}                  \n" /* exception return value */
-#if defined(CPU_ARCH_CORTEX_M4F) || defined(CPU_ARCH_CORTEX_M7)
-/*  "vstmdb sp!, {s16-s31}            \n" */ /* TODO save FPU registers */
-#endif
 #endif
     "ldr    r1, =sched_active_thread  \n" /* load address of current tcb */
     "ldr    r1, [r1]                  \n" /* dereference pdc */
@@ -364,14 +350,16 @@ void __attribute__((naked)) __attribute__((used)) isr_svc(void) {
     "ldr    r0, [r0]                  \n" /* dereference TCB */
     "ldr    r1, [r0]                  \n" /* load tcb->sp to register 1 */
     "ldmia  r1!, {r0}                 \n" /* restore exception return value */
-#if defined(CPU_ARCH_CORTEX_M4F) || defined(CPU_ARCH_CORTEX_M7)
-/*  "pop    {s16-s31}                 \n" */ /* TODO load FPU registers */
-#endif
     "ldmia  r1!, {r4-r11}             \n" /* restore other registers */
+#if (defined(CPU_ARCH_CORTEX_M4F) || defined(CPU_ARCH_CORTEX_M7)) && defined(MODULE_CORTEXM_FPU)
+    "tst    r0, #0x10                 \n"
+    "it     eq                        \n"
+    "vldmiaeq r1!, {s16-s31}          \n" /* load FPU registers if saved */
+#endif
     "msr    psp, r1                   \n" /* restore user mode SP to PSP reg */
     "bx     r0                        \n" /* load exception return value to PC,
                                            * causes end of exception*/
 #endif
-    /* {r0-r3,r12,LR,PC,xPSR} are restored automatically on exception return */
+    /* {r0-r3,r12,LR,PC,xPSR,s0-s15,FPSCR} are restored automatically on exception return */
     );
 }
diff --git a/makefiles/arch/cortexm.inc.mk b/makefiles/arch/cortexm.inc.mk
@@ -63,14 +63,29 @@ ARCH = $(shell echo $(CPU_ARCH) | tr 'a-z-' 'A-Z_')
 export CFLAGS += -DCPU_ARCH_$(ARCH)
 
 # set the compiler specific CPU and FPU options
-ifeq ($(CPU_ARCH),cortex-m4f)
-# TODO: enable hard floating points for the M4F once the context save/restore
-#       code is adjusted to take care of FPU registers
-#export CFLAGS_FPU += -mfloat-abi=hard -mfpu=fpv4-sp-d16
-export MCPU := cortex-m4
-endif
+ifneq (,$(filter $(CPU_ARCH),cortex-m4f cortex-m7))
+    ifneq (,$(filter cortexm_fpu,$(DISABLE_MODULE)))
+        export CFLAGS_FPU ?= -mfloat-abi=soft
+    else
+        USEMODULE += cortexm_fpu
+        # clang assumes there is an FPU
+        ifneq (llvm,$(TOOLCHAIN))
+            ifeq ($(CPU_ARCH),cortex-m7)
+                export CFLAGS_FPU ?= -mfloat-abi=hard -mfpu=fpv5-d16
+            else
+                export CFLAGS_FPU ?= -mfloat-abi=hard -mfpu=fpv4-sp-d16
+            endif
+        endif
+    endif
+    ifeq ($(CPU_ARCH),cortex-m4f)
+        export MCPU := cortex-m4
+    else
+        export MCPU ?= $(CPU_ARCH)
+    endif
+else
 CFLAGS_FPU ?= -mfloat-abi=soft
 export MCPU ?= $(CPU_ARCH)
+endif
 
 # CMSIS DSP needs to know about the CPU core
 ifneq (,$(filter cmsis-dsp,$(USEPKG)))

diff --git a/makefiles/pseudomodules.inc.mk b/makefiles/pseudomodules.inc.mk
@@ -8,6 +8,7 @@ PSEUDOMODULES += conn_can_isotp_multi
 PSEUDOMODULES += cord_ep_standalone
 PSEUDOMODULES += cord_epsim_standalone
 PSEUDOMODULES += core_%
+PSEUDOMODULES += cortexm_fpu
 PSEUDOMODULES += ecc_%
 PSEUDOMODULES += emb6_router
 PSEUDOMODULES += event_%