misc: tegra-throughput: adding throughput dev node

Creates a miscdev at /dev/tegra-throughput which gl will use to set a
target frame rate. In addition it receives notifications from dc on
flip events. On each notification the percentage ratio of the actual
frame time to the target frame time is calculated. In subsequent
changes this ratio will be reported to other modules as a throughput
hint.

Bug 991589

Change-Id: Ieaa2b2755b63d2d071de31e3ef819d4c3b51a956
Signed-off-by: Ilan Aelion <iaelion@nvidia.com>
Reviewed-on: http://git-master/r/116865
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Diwakar Tundlam <dtundlam@nvidia.com>
Reviewed-by: Jon Mayo <jmayo@nvidia.com>

3 files changed, 239 insertions, 0 deletions

diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index dcf345e23487..0d6210e50e43 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -568,6 +568,13 @@ config THERM_EST
 	---help---
 	Thermal driver which estimates temperature based of other sensors.
 
+config TEGRA_THROUGHPUT
+	bool "Device node to set throughput target"
+	depends on TEGRA_DC && TEGRA_DC_EXTENSIONS
+	default y
+	---help---
+	Dev node /dev/tegra-throughput used to set a throughput target.
+
 source "drivers/misc/c2port/Kconfig"
 source "drivers/misc/eeprom/Kconfig"
 source "drivers/misc/cb710/Kconfig"
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index d9172c99bf6d..39d1427ae549 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -60,3 +60,4 @@ obj-$(CONFIG_TEGRA_BB_SUPPORT)	+= tegra-baseband/
 obj-$(CONFIG_TEGRA_CEC_SUPPORT)	+= tegra-cec/
 obj-$(CONFIG_MAX1749_VIBRATOR)	+= max1749.o
 obj-$(CONFIG_THERM_EST)		+= therm_est.o
+obj-$(CONFIG_TEGRA_THROUGHPUT)	+= tegra-throughput.o
diff --git a/drivers/misc/tegra-throughput.c b/drivers/misc/tegra-throughput.c
new file mode 100644
index 000000000000..c909a81d0882
--- /dev/null
+++ b/drivers/misc/tegra-throughput.c
@@ -0,0 +1,231 @@
+/*
+ * drivers/misc/throughput.c
+ *
+ * Copyright (C) 2012, NVIDIA CORPORATION. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, version 2 of the License.
+ *
+ * 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.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+
+#include <linux/kthread.h>
+#include <linux/ktime.h>
+#include <linux/notifier.h>
+#include <linux/miscdevice.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/spinlock.h>
+#include <linux/throughput_ioctl.h>
+#include <mach/dc.h>
+
+#define DEFAULT_SYNC_RATE 60000 /* 60 Hz */
+
+static unsigned short target_frame_time;
+static unsigned short last_frame_time;
+static ktime_t last_flip;
+static unsigned int multiple_app_disable;
+
+static spinlock_t lock;
+
+static int throughput_flip_notifier(struct notifier_block *nb,
+					     unsigned long val,
+					     void *data)
+{
+	/* only register flips when a single display is active */
+	if (val != 1 || multiple_app_disable)
+		return NOTIFY_DONE;
+	else {
+		long timediff;
+		ktime_t now;
+		int throughput_hint;
+
+		now = ktime_get();
+		if (last_flip.tv64 != 0) {
+			timediff = (long) ktime_us_delta(now, last_flip);
+			if (timediff > (long) USHRT_MAX)
+				last_frame_time = USHRT_MAX;
+			else
+				last_frame_time = (unsigned short) timediff;
+
+			throughput_hint =
+				((int) target_frame_time * 100)/last_frame_time;
+
+			/* notify throughput hint clients here */
+		}
+		last_flip = now;
+	}
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block throughput_flip_nb = {
+	.notifier_call = throughput_flip_notifier,
+};
+
+static int sync_rate;
+static int throughput_active_app_count;
+
+static void reset_target_frame_time(void)
+{
+	if (sync_rate == 0) {
+		sync_rate = tegra_dc_get_panel_sync_rate();
+
+		if (sync_rate == 0)
+			sync_rate = DEFAULT_SYNC_RATE;
+	}
+
+	target_frame_time = (unsigned short) (1000000000 / sync_rate);
+
+	pr_debug("%s: panel sync rate %d, target frame time %u\n",
+		__func__, sync_rate, target_frame_time);
+}
+
+static int notifier_initialized;
+
+static int throughput_open(struct inode *inode, struct file *file)
+{
+	if (!notifier_initialized) {
+		tegra_dc_register_flip_notifier(&throughput_flip_nb);
+		notifier_initialized = 1;
+	}
+
+	spin_lock(&lock);
+
+	throughput_active_app_count++;
+	if (throughput_active_app_count > 1)
+		multiple_app_disable = 1;
+
+	spin_unlock(&lock);
+
+	pr_debug("throughput_open node %p file %p\n", inode, file);
+
+	return 0;
+}
+
+static int throughput_release(struct inode *inode, struct file *file)
+{
+	spin_lock(&lock);
+	throughput_active_app_count--;
+	spin_unlock(&lock);
+
+	if (throughput_active_app_count == 0) {
+		reset_target_frame_time();
+		multiple_app_disable = 0;
+		tegra_dc_unregister_flip_notifier(&throughput_flip_nb);
+		notifier_initialized = 0;
+	}
+
+
+	pr_debug("throughput_release node %p file %p\n", inode, file);
+
+	return 0;
+}
+
+static int throughput_set_target_fps(unsigned long arg)
+{
+	int disable;
+
+	pr_debug("%s: target fps %lu requested\n", __func__, arg);
+
+	disable = multiple_app_disable;
+
+	if (disable) {
+		pr_debug("%s: %d active apps, disabling fps usage\n",
+			__func__, throughput_active_app_count);
+		return 0;
+	}
+
+	if (arg == 0)
+		reset_target_frame_time();
+	else {
+		unsigned long frame_time = (1000000 / arg);
+
+		if (frame_time > USHRT_MAX)
+			frame_time = USHRT_MAX;
+
+		target_frame_time = (unsigned short) frame_time;
+	}
+
+	return 0;
+}
+
+static long
+throughput_ioctl(struct file *file,
+			  unsigned int cmd,
+			  unsigned long arg)
+{
+	int err = 0;
+
+	if ((_IOC_TYPE(cmd) != TEGRA_THROUGHPUT_MAGIC) ||
+		(_IOC_NR(cmd) == 0) ||
+		(_IOC_NR(cmd) > TEGRA_THROUGHPUT_IOCTL_MAXNR))
+		return -EFAULT;
+
+	switch (cmd) {
+	case TEGRA_THROUGHPUT_IOCTL_TARGET_FPS:
+		pr_debug("%s: TEGRA_THROUGHPUT_IOCTL_TARGET_FPS %lu\n",
+			__func__, arg);
+		err = throughput_set_target_fps(arg);
+		break;
+
+	default:
+		err = -ENOTTY;
+	}
+
+	return err;
+}
+
+static const struct file_operations throughput_user_fops = {
+	.owner			= THIS_MODULE,
+	.open			= throughput_open,
+	.release		= throughput_release,
+	.unlocked_ioctl		= throughput_ioctl,
+};
+
+#define TEGRA_THROUGHPUT_MINOR 1
+
+static struct miscdevice throughput_miscdev = {
+	.minor  = TEGRA_THROUGHPUT_MINOR,
+	.name   = "tegra-throughput",
+	.fops   = &throughput_user_fops,
+	.mode   = 0666,
+};
+
+int __init throughput_init_miscdev(void)
+{
+	int ret;
+
+	pr_debug("%s: initializing\n", __func__);
+
+	spin_lock_init(&lock);
+
+	ret = misc_register(&throughput_miscdev);
+	if (ret) {
+		pr_err("can\'t reigster throughput miscdev"
+		       " (minor %d err %d)\n", TEGRA_THROUGHPUT_MINOR, ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+module_init(throughput_init_miscdev);
+
+void __exit throughput_exit_miscdev(void)
+{
+	pr_debug("%s: exiting\n", __func__);
+
+	misc_deregister(&throughput_miscdev);
+}
+
+module_exit(throughput_exit_miscdev);
+