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authorHelge Deller <deller@gmx.de>2018-01-05 21:55:38 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-01-10 09:31:22 +0100
commita0fdea2a407e0f2503f6b80b1a89c44fb58d64e9 (patch)
tree3e69f073d991f997b871f77b343a9f234dd35be2
parentfb510265edaf4809c050e620231b6ea69507fe82 (diff)
parisc: qemu idle sleep support
commit 310d82784fb4d60c80569f5ca9f53a7f3bf1d477 upstream. Add qemu idle sleep support when running under qemu with SeaBIOS PDC firmware. Like the power architecture we use the "or" assembler instructions, which translate to nops on real hardware, to indicate that qemu shall idle sleep. Signed-off-by: Helge Deller <deller@gmx.de> Cc: Richard Henderson <rth@twiddle.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--arch/parisc/kernel/process.c39
1 files changed, 39 insertions, 0 deletions
diff --git a/arch/parisc/kernel/process.c b/arch/parisc/kernel/process.c
index 30f92391a93e..cad3e8661cd6 100644
--- a/arch/parisc/kernel/process.c
+++ b/arch/parisc/kernel/process.c
@@ -39,6 +39,7 @@
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/fs.h>
+#include <linux/cpu.h>
#include <linux/module.h>
#include <linux/personality.h>
#include <linux/ptrace.h>
@@ -184,6 +185,44 @@ int dump_task_fpu (struct task_struct *tsk, elf_fpregset_t *r)
}
/*
+ * Idle thread support
+ *
+ * Detect when running on QEMU with SeaBIOS PDC Firmware and let
+ * QEMU idle the host too.
+ */
+
+int running_on_qemu __read_mostly;
+
+void __cpuidle arch_cpu_idle_dead(void)
+{
+ /* nop on real hardware, qemu will offline CPU. */
+ asm volatile("or %%r31,%%r31,%%r31\n":::);
+}
+
+void __cpuidle arch_cpu_idle(void)
+{
+ local_irq_enable();
+
+ /* nop on real hardware, qemu will idle sleep. */
+ asm volatile("or %%r10,%%r10,%%r10\n":::);
+}
+
+static int __init parisc_idle_init(void)
+{
+ const char *marker;
+
+ /* check QEMU/SeaBIOS marker in PAGE0 */
+ marker = (char *) &PAGE0->pad0;
+ running_on_qemu = (memcmp(marker, "SeaBIOS", 8) == 0);
+
+ if (!running_on_qemu)
+ cpu_idle_poll_ctrl(1);
+
+ return 0;
+}
+arch_initcall(parisc_idle_init);
+
+/*
* Copy architecture-specific thread state
*/
int