@@ -2227,6 +2227,13 @@ config NEON
Say Y to include support code for NEON, the ARMv7 Advanced SIMD
Extension.
+config VFPM
+ bool "ARMv7-M VFP Extension support"
+ depends on CPU_V7M
+ help
+ Say Y to include support for the ARMv7-M VFP Extension
+ (single-precision floating point hardware).
+
endmenu
menu "Userspace binary formats"
@@ -43,6 +43,9 @@ struct vfp_hard_struct {
#ifdef CONFIG_SMP
__u32 cpu;
#endif
+#ifdef CONFIG_VFPM
+ __u32 clean;
+#endif
};
union vfp_state {
@@ -81,6 +81,8 @@ obj-$(CONFIG_HW_PERF_EVENTS) += perf_event.o
AFLAGS_iwmmxt.o := -Wa,-mcpu=iwmmxt
obj-$(CONFIG_ARM_CPU_TOPOLOGY) += topology.o
+obj-$(CONFIG_VFPM) += vfp-m.o
+
ifneq ($(CONFIG_ARCH_EBSA110),y)
obj-y += io.o
endif
@@ -60,6 +60,9 @@ int main(void)
DEFINE(TI_TP_VALUE, offsetof(struct thread_info, tp_value));
DEFINE(TI_FPSTATE, offsetof(struct thread_info, fpstate));
DEFINE(TI_VFPSTATE, offsetof(struct thread_info, vfpstate));
+#ifdef CONFIG_VFPM
+ DEFINE(TI_VFPSTATE_CLEAN, offsetof(struct thread_info, vfpstate.hard.clean));
+#endif
#ifdef CONFIG_SMP
DEFINE(VFP_CPU, offsetof(union vfp_state, hard.cpu));
#endif
@@ -72,7 +72,15 @@
*/
.macro v7m_exception_entry
cpsid i
+#ifdef CONFIG_VFPM
+ get_thread_info r0
+ and r1, lr, #1 << 4 @ VFP clean state
+ str r1, [r0, #TI_VFPSTATE_CLEAN]
+#endif
cmp lr, #0xfffffffd @ check the return stack
+#ifdef CONFIG_VFPM
+ cmpne lr, #0xffffffed
+#endif
beq 1f @ exception on process stack
add r12, sp, #32 @ MSP before exception
stmdb sp!, {r4-r12, lr} @ push unsaved registers
@@ -90,6 +98,9 @@
.macro v7m_exception_fast_exit
ldmia sp!, {r4-r12, lr} @ restore previously saved state
cmp lr, #0xfffffffd @ check the return stack
+#ifdef CONFIG_VFPM
+ cmpne lr, #0xffffffed
+#endif
addeq sp, #32 @ returning to PSP, just restore MSP
cpsie i
bx lr
@@ -99,6 +110,9 @@
cpsid i
ldr lr, [sp, #S_EXC_LR] @ read exception LR
cmp lr, #0xfffffffd @ check the return stack
+#ifdef CONFIG_VFPM
+ cmpne lr, #0xffffffed
+#endif
beq 1f @ returning to PSP
@ Prepare the MSP stack
ldmia sp, {r4-r11} @ restore previously saved state
new file mode 100644
@@ -0,0 +1,102 @@
+/*
+ * arch/arm/kernel/vfp-m.c
+ *
+ * Copyright (C) 2010 ARM Limited
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/string.h>
+
+#include <asm/thread_notify.h>
+
+static union vfp_state *last_vfp_context;
+
+static void save_vfp_context(union vfp_state *vfp)
+{
+ /* vstmia %0!, {d8-d15} */
+ asm(" stc p11, cr8, [%0], #16*4\n" : : "r" (vfp) : "cc");
+}
+
+static void load_vfp_context(union vfp_state *vfp)
+{
+ /* vldmia %0!, {d8-d15} */
+ asm(" ldc p11, cr8, [%0], #16*4\n" : : "r" (vfp) : "cc");
+}
+
+static int vfpm_notifier(struct notifier_block *self, unsigned long cmd,
+ void *t)
+{
+ struct thread_info *thread = t;
+ union vfp_state *vfp = &thread->vfpstate;
+ union vfp_state *old_vfp = ¤t_thread_info()->vfpstate;
+ u32 *fpccr = (u32 *)0xe000ef34;
+
+ switch (cmd) {
+ case THREAD_NOTIFY_FLUSH:
+ memset(vfp, 0, sizeof(*vfp));
+ vfp->hard.clean = 1;
+ /* fall through */
+
+ case THREAD_NOTIFY_EXIT:
+ if (last_vfp_context == vfp) {
+ /* disable lazy state saving */
+ *fpccr &= ~1;
+ last_vfp_context = NULL;
+ }
+ break;
+
+ case THREAD_NOTIFY_SWITCH:
+ if (!old_vfp->hard.clean) {
+ save_vfp_context(last_vfp_context);
+ last_vfp_context = old_vfp;
+ }
+ if (!vfp->hard.clean && last_vfp_context != vfp) {
+ load_vfp_context(vfp);
+ last_vfp_context = vfp;
+ }
+ break;
+ }
+
+ return NOTIFY_DONE;
+}
+
+static struct notifier_block vfpm_notifier_block = {
+ .notifier_call = vfpm_notifier,
+};
+
+static int __init vfpm_init(void)
+{
+ u32 *cpacr = (u32 *)0xe000ed88;
+ u32 *mvfr0 = (u32 *)0xe000ef40;
+ u32 *fpccr = (u32 *)0xe000ef34;
+
+ /* check for single-precision VFP operations */
+ if ((*mvfr0 & 0xf0) != 0x20)
+ return 0;
+
+ printk(KERN_INFO "ARMv7-M VFP Extension supported\n");
+
+ *cpacr |= 0xf << 20; /* coprocessor access */
+ *fpccr |= 3 << 30; /* automatic lazy state preservation */
+
+ elf_hwcap |= HWCAP_VFP;
+ thread_register_notifier(&vfpm_notifier_block);
+
+ return 0;
+}
+
+late_initcall(vfpm_init);