[PATCH 11/13] PM: earlysuspend: Removing dependence on console.

Arve Hjønnevåg
2009-02-05T02:50:24Z

From: Rebecca Schultz <rschultz@google.com>

Rather than signaling a full update of the display from userspace via a
console switch, this patch introduces 2 files int /sys/power,
wait_for_fb_sleep and wait_for_fb_wake. Reading these files will block
until the requested state has been entered. When a read from
wait_for_fb_sleep returns userspace should stop drawing. When
wait_for_fb_wake returns, it should do a full update. If either are called
when the fb driver is already in the requested state, they will return
immediately.

Signed-off-by: Rebecca Schultz <rschultz@google.com>
Signed-off-by: Arve Hjønnevåg <arve@android.com>
---
kernel/power/Kconfig | 9 +++
kernel/power/Makefile | 1 +
kernel/power/fbearlysuspend.c | 153 +++++++++++++++++++++++++++++++++++++++++
3 files changed, 163 insertions(+), 0 deletions(-)
create mode 100644 kernel/power/fbearlysuspend.c

diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index f1a3d5c..616341d 100644
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -168,6 +168,7 @@ config EARLYSUSPEND

choice
prompt "User-space screen access"
+ default FB_EARLYSUSPEND if !FRAMEBUFFER_CONSOLE
default CONSOLE_EARLYSUSPEND
depends on HAS_EARLYSUSPEND

@@ -181,6 +182,14 @@ choice
Register early suspend handler to perform a console switch to
when user-space should stop drawing to the screen and a switch
back when it should resume.
+
+ config FB_EARLYSUSPEND
+ bool "Sysfs interface"
+ depends on HAS_EARLYSUSPEND
+ ---help---
+ Register early suspend handler that notifies and waits for
+ user-space through sysfs when user-space should stop drawing
+ to the screen and notifies user-space when it should resume.
endchoice

config HIBERNATION
diff --git a/kernel/power/Makefile b/kernel/power/Makefile
index 8bf293d..5beaa21 100644
--- a/kernel/power/Makefile
+++ b/kernel/power/Makefile
@@ -10,6 +10,7 @@ obj-$(CONFIG_WAKELOCK) += wakelock.o
obj-$(CONFIG_USER_WAKELOCK) += userwakelock.o
obj-$(CONFIG_EARLYSUSPEND) += earlysuspend.o
obj-$(CONFIG_CONSOLE_EARLYSUSPEND) += consoleearlysuspend.o
+obj-$(CONFIG_FB_EARLYSUSPEND) += fbearlysuspend.o
obj-$(CONFIG_HIBERNATION) += swsusp.o disk.o snapshot.o swap.o user.o

obj-$(CONFIG_MAGIC_SYSRQ) += poweroff.o
diff --git a/kernel/power/fbearlysuspend.c b/kernel/power/fbearlysuspend.c
new file mode 100644
index 0000000..1513765
--- /dev/null
+++ b/kernel/power/fbearlysuspend.c
@@ -0,0 +1,153 @@
+/* kernel/power/fbearlysuspend.c
+ *
+ * Copyright (C) 2005-2008 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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.
+ *
+ */
+
+#include <linux/earlysuspend.h>
+#include <linux/module.h>
+#include <linux/wait.h>
+
+#include "power.h"
+
+static wait_queue_head_t fb_state_wq;
+static DEFINE_SPINLOCK(fb_state_lock);
+static enum {
+ FB_STATE_STOPPED_DRAWING,
+ FB_STATE_REQUEST_STOP_DRAWING,
+ FB_STATE_DRAWING_OK,
+} fb_state;
+
+/* tell userspace to stop drawing, wait for it to stop */
+static void stop_drawing_early_suspend(struct early_suspend *h)
+{
+ int ret;
+ unsigned long irq_flags;
+
+ spin_lock_irqsave(&fb_state_lock, irq_flags);
+ fb_state = FB_STATE_REQUEST_STOP_DRAWING;
+ spin_unlock_irqrestore(&fb_state_lock, irq_flags);
+
+ wake_up_all(&fb_state_wq);
+ ret = wait_event_timeout(fb_state_wq,
+ fb_state == FB_STATE_STOPPED_DRAWING,
+ HZ);
+ if (unlikely(fb_state != FB_STATE_STOPPED_DRAWING))
+ pr_warning("stop_drawing_early_suspend: timeout waiting for "
+ "userspace to stop drawing\n");
+}
+
+/* tell userspace to start drawing */
+static void start_drawing_late_resume(struct early_suspend *h)
+{
+ unsigned long irq_flags;
+
+ spin_lock_irqsave(&fb_state_lock, irq_flags);
+ fb_state = FB_STATE_DRAWING_OK;
+ spin_unlock_irqrestore(&fb_state_lock, irq_flags);
+ wake_up(&fb_state_wq);
+}
+
+static struct early_suspend stop_drawing_early_suspend_desc = {
+ .level = EARLY_SUSPEND_LEVEL_STOP_DRAWING,
+ .suspend = stop_drawing_early_suspend,
+ .resume = start_drawing_late_resume,
+};
+
+static ssize_t wait_for_fb_sleep_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ char *s = buf;
+ int ret;
+
+ ret = wait_event_interruptible(fb_state_wq,
+ fb_state != FB_STATE_DRAWING_OK);
+ if (ret && fb_state == FB_STATE_DRAWING_OK)
+ return ret;
+ else
+ s += sprintf(buf, "sleeping");
+ return s - buf;
+}
+
+static ssize_t wait_for_fb_wake_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ char *s = buf;
+ int ret;
+ unsigned long irq_flags;
+
+ spin_lock_irqsave(&fb_state_lock, irq_flags);
+ if (fb_state == FB_STATE_REQUEST_STOP_DRAWING) {
+ fb_state = FB_STATE_STOPPED_DRAWING;
+ wake_up(&fb_state_wq);
+ }
+ spin_unlock_irqrestore(&fb_state_lock, irq_flags);
+
+ ret = wait_event_interruptible(fb_state_wq,
+ fb_state == FB_STATE_DRAWING_OK);
+ if (ret && fb_state != FB_STATE_DRAWING_OK)
+ return ret;
+ else
+ s += sprintf(buf, "awake");
+
+ return s - buf;
+}
+
+#define power_ro_attr(_name) \
+static struct kobj_attribute _name##_attr = { \
+ .attr = { \
+ .name = __stringify(_name), \
+ .mode = 0444, \
+ }, \
+ .show = _name##_show, \
+ .store = NULL, \
+}
+
+power_ro_attr(wait_for_fb_sleep);
+power_ro_attr(wait_for_fb_wake);
+
+static struct attribute *g[] = {
+ &wait_for_fb_sleep_attr.attr,
+ &wait_for_fb_wake_attr.attr,
+ NULL,
+};
+
+static struct attribute_group attr_group = {
+ .attrs = g,
+};
+
+static int __init android_power_init(void)
+{
+ int ret;
+
+ init_waitqueue_head(&fb_state_wq);
+ fb_state = FB_STATE_DRAWING_OK;
+
+ ret = sysfs_create_group(power_kobj, &attr_group);
+ if (ret) {
+ pr_err("android_power_init: sysfs_create_group failed\n");
+ return ret;
+ }
+
+ register_early_suspend(&stop_drawing_early_suspend_desc);
+ return 0;
+}
+
+static void __exit android_power_exit(void)
+{
+ unregister_early_suspend(&stop_drawing_early_suspend_desc);
+ sysfs_remove_group(power_kobj, &attr_group);
+}
+
+module_init(android_power_init);
+module_exit(android_power_exit);
+
--
1.6.1

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