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authorBen Dooks <ben-linux@fluff.org>2008-12-18 12:26:54 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2008-12-18 21:21:34 +0000
commitfc0b7a20368193e1f7cf1376624eed419b9c33e6 (patch)
tree6b1364b1b4bb7cee7bec720d28bd75ba4794aff9 /arch/arm/vfp
parentc95a44329e816d2f9da21b27e74615d5ee0d2333 (diff)
[ARM] 5349/1: VFP: Add PM code to save and restore current VFP state
When CONFIG_PM is selected, the VFP code does not have any handler installed to deal with either saving the VFP state of the current task, nor does it do anything to try and restore the VFP after a resume. On resume, the VFP will have been reset and the co-processor access control registers are in an indeterminate state (very probably the CP10 and CP11 the VFP uses will have been disabled by the ARM core reset). When this happens, resume will break as soon as it tries to unfreeze the tasks and restart scheduling. Add a sys device to allow us to hook the suspend call to save the current thread state if the thread is using VFP and a resume hook which restores the CP10/CP11 access and ensures the VFP is disabled so that the lazy swapping will take place on next access. Signed-off-by: Ben Dooks <ben-linux@fluff.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/vfp')
-rw-r--r--arch/arm/vfp/vfp.h2
-rw-r--r--arch/arm/vfp/vfphw.S2
-rw-r--r--arch/arm/vfp/vfpmodule.c56
3 files changed, 58 insertions, 2 deletions
diff --git a/arch/arm/vfp/vfp.h b/arch/arm/vfp/vfp.h
index c85860bad585..8de86e4feada 100644
--- a/arch/arm/vfp/vfp.h
+++ b/arch/arm/vfp/vfp.h
@@ -377,6 +377,6 @@ struct op {
u32 flags;
};
-#ifdef CONFIG_SMP
+#if defined(CONFIG_SMP) || defined(CONFIG_PM)
extern void vfp_save_state(void *location, u32 fpexc);
#endif
diff --git a/arch/arm/vfp/vfphw.S b/arch/arm/vfp/vfphw.S
index 3c73aafe3e01..c92a08bd6a86 100644
--- a/arch/arm/vfp/vfphw.S
+++ b/arch/arm/vfp/vfphw.S
@@ -172,7 +172,7 @@ process_exception:
@ retry the faulted instruction
ENDPROC(vfp_support_entry)
-#ifdef CONFIG_SMP
+#if defined(CONFIG_SMP) || defined(CONFIG_PM)
ENTRY(vfp_save_state)
@ Save the current VFP state
@ r0 - save location
diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
index 67ca340a7c85..9f476a1be2ca 100644
--- a/arch/arm/vfp/vfpmodule.c
+++ b/arch/arm/vfp/vfpmodule.c
@@ -322,6 +322,61 @@ static void vfp_enable(void *unused)
set_copro_access(access | CPACC_FULL(10) | CPACC_FULL(11));
}
+#ifdef CONFIG_PM
+#include <linux/sysdev.h>
+
+static int vfp_pm_suspend(struct sys_device *dev, pm_message_t state)
+{
+ struct thread_info *ti = current_thread_info();
+ u32 fpexc = fmrx(FPEXC);
+
+ /* if vfp is on, then save state for resumption */
+ if (fpexc & FPEXC_EN) {
+ printk(KERN_DEBUG "%s: saving vfp state\n", __func__);
+ vfp_save_state(&ti->vfpstate, fpexc);
+
+ /* disable, just in case */
+ fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN);
+ }
+
+ /* clear any information we had about last context state */
+ memset(last_VFP_context, 0, sizeof(last_VFP_context));
+
+ return 0;
+}
+
+static int vfp_pm_resume(struct sys_device *dev)
+{
+ /* ensure we have access to the vfp */
+ vfp_enable(NULL);
+
+ /* and disable it to ensure the next usage restores the state */
+ fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN);
+
+ return 0;
+}
+
+static struct sysdev_class vfp_pm_sysclass = {
+ .name = "vfp",
+ .suspend = vfp_pm_suspend,
+ .resume = vfp_pm_resume,
+};
+
+static struct sys_device vfp_pm_sysdev = {
+ .cls = &vfp_pm_sysclass,
+};
+
+static void vfp_pm_init(void)
+{
+ sysdev_class_register(&vfp_pm_sysclass);
+ sysdev_register(&vfp_pm_sysdev);
+}
+
+
+#else
+static inline void vfp_pm_init(void) { }
+#endif /* CONFIG_PM */
+
#include <linux/smp.h>
/*
@@ -365,6 +420,7 @@ static int __init vfp_init(void)
vfp_vector = vfp_support_entry;
thread_register_notifier(&vfp_notifier_block);
+ vfp_pm_init();
/*
* We detected VFP, and the support code is