On Apr 4, 2008, at 3:06 AM, Jerone Young wrote:
# HG changeset patch
# User Jerone Young <[EMAIL PROTECTED]>
# Date 1207292108 18000
# Node ID afed3e5de82ab6c0ac8d6ceeb0292b6c41ece1ed
# Parent a5b2aebbc6ebd2439c655f1c047ed7e3c1991ec1
[v2] Add idle wait support for 44x platforms
This patch adds the ability for the CPU to go into wait state while
in cpu_idle loop. This helps virtulization solutions know when the
guest Linux kernel is in an idle state. There are two ways to do it.
1) Command line
idle=spin <-- CPU will spin (this is the default)
idle=wait <-- set CPU into wait state when idle
2) The device tree will be checked for the "/hypervisor" node
If this node is seen it will use "wait" for idle, so that
the hypervisor can know when guest Linux kernel it is in
an idle state.
This patch, unlike the last, isolates the code to 44x platforms.
Signed-off-by: Jerone Young <[EMAIL PROTECTED]>
diff --git a/arch/powerpc/platforms/44x/Makefile b/arch/powerpc/
platforms/44x/Makefile
--- a/arch/powerpc/platforms/44x/Makefile
+++ b/arch/powerpc/platforms/44x/Makefile
@@ -1,4 +1,4 @@ obj-$(CONFIG_44x) := misc_44x.o
-obj-$(CONFIG_44x) := misc_44x.o
+obj-$(CONFIG_44x) := misc_44x.o idle.o
obj-$(CONFIG_EBONY) += ebony.o
obj-$(CONFIG_TAISHAN) += taishan.o
obj-$(CONFIG_BAMBOO) += bamboo.o
diff --git a/arch/powerpc/platforms/44x/idle.c b/arch/powerpc/
platforms/44x/idle.c
new file mode 100644
--- /dev/null
+++ b/arch/powerpc/platforms/44x/idle.c
@@ -0,0 +1,84 @@
+/*
+ * Copyright 2008 IBM Corp.
+ *
+ * Derived from pasemi/idle.c
+ * by Olof Johansson <[EMAIL PROTECTED]>
+ *
+ * Added by: Jerone Young <[EMAIL PROTECTED]>
+ *
+ * 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/of.h>
+#include <linux/kernel.h>
+#include <asm/machdep.h>
+
+static int current_mode = 0;
Doesn't matter if the 0 is functionally redundant or pleasing to your
eye, it is the "Linux way" to leave out the " = 0", so just do it
please.
+
+struct sleep_mode {
+ char *name;
+ void (*entry)(void);
+};
+
+static void ppc44x_idle(void)
Perhaps "ppc44x_wait" is more appropriate?
+{
+ unsigned long msr_save;
+
+ msr_save = mfmsr();
+ /* set wait state MSR */
+ mtmsr(msr_save|MSR_WE|MSR_EE|MSR_CE);
Did we decide to drop MSR_DE?
+ /* return to initial state */
+ mtmsr(msr_save);
It may be my paranoia but I'm pretty sure you need the isync() after
_both_ mtmsr()s
Certainly can't hurt.
+}
+
+static struct sleep_mode modes[] = {
+ { .name = "spin", .entry = NULL },
+ { .name = "wait", .entry = &ppc44x_idle },
+};
+
+int __init ppc44x_idle_init(void)
+{
+ void *func = modes[current_mode].entry;
+ struct device_node *node;
+
+ node = of_find_node_by_path("/hypervisor");
+ if (node) {
+ /* if we find /hypervisor node is in device tree,
+ set idle mode to wait */
+ func = &ppc44x_idle; /* wait */
+ of_node_put(node);
+ }
+
+ ppc_md.power_save = func;
+ return 0;
+}
+
+arch_initcall(ppc44x_idle_init);
IIRC, this would over-ride the idle_param() below, is that the
intended behavior?
+
+static int __init idle_param(char *p)
+{
+ int i;
+
+ for (i = 0; i < sizeof(modes)/ARRAY_SIZE(modes); i++) {
It is supposed to be:
for (i = 0; i < ARRAY_SIZE(modes); i++) {
What you have will actually eval to 0 and would have never checked
anything :)
+ if (!strcmp(modes[i].name, p)) {
+ current_mode = i;
+ break;
+ }
+ }
+
+ return 0;
+}
+
+early_param("idle", idle_param);
----------------------------------------------------------------------
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