aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorHelge Deller <deller@gmx.de>2018-01-05 21:55:38 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-01-10 09:29:54 +0100
commit91dfc41e753bb4e7d3948b02baca60ac40c4cbfd (patch)
treeec958ff319ac6590e75cf497cf034db22991f7e0
parent14c06206b98f3d11ff250875f6046df8d825f13d (diff)
downloadlinux-linaro-stable-91dfc41e753bb4e7d3948b02baca60ac40c4cbfd.tar.gz
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 7593787ed4c3..c3a532abac03 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>
@@ -181,6 +182,44 @@ 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