PM / OPP: Add debugfs support

This patch adds debugfs support to OPP layer to export OPPs and their
properties for all the devices.

This creates a top level directory: /sys/kernel/debug/opp and then
device specific directories (based on device names) inside it. For
example: 'cpu0', 'cpu1', etc..

If multiple devices share the OPP table, then the real directory is
created only for the first device. For all others, links are created to
the real directory.

Inside the device specific directory, a separate directory is created
for each OPP. And within that files per opp property.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 219 insertions, 0 deletions

diff --git a/drivers/base/power/opp/debugfs.c b/drivers/base/power/opp/debugfs.c
new file mode 100644
index 000000000000..ddfe4773e922
--- /dev/null
+++ b/drivers/base/power/opp/debugfs.c
@@ -0,0 +1,219 @@
+/*
+ * Generic OPP debugfs interface
+ *
+ * Copyright (C) 2015-2016 Viresh Kumar <viresh.kumar@linaro.org>
+ *
+ * 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.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/debugfs.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/limits.h>
+
+#include "opp.h"
+
+static struct dentry *rootdir;
+
+static void opp_set_dev_name(const struct device *dev, char *name)
+{
+	if (dev->parent)
+		snprintf(name, NAME_MAX, "%s-%s", dev_name(dev->parent),
+			 dev_name(dev));
+	else
+		snprintf(name, NAME_MAX, "%s", dev_name(dev));
+}
+
+void opp_debug_remove_one(struct dev_pm_opp *opp)
+{
+	debugfs_remove_recursive(opp->dentry);
+}
+
+int opp_debug_create_one(struct dev_pm_opp *opp, struct device_opp *dev_opp)
+{
+	struct dentry *pdentry = dev_opp->dentry;
+	struct dentry *d;
+	char name[25];	/* 20 chars for 64 bit value + 5 (opp:\0) */
+
+	/* Rate is unique to each OPP, use it to give opp-name */
+	snprintf(name, sizeof(name), "opp:%lu", opp->rate);
+
+	/* Create per-opp directory */
+	d = debugfs_create_dir(name, pdentry);
+	if (!d)
+		return -ENOMEM;
+
+	if (!debugfs_create_bool("available", S_IRUGO, d, &opp->available))
+		return -ENOMEM;
+
+	if (!debugfs_create_bool("dynamic", S_IRUGO, d, &opp->dynamic))
+		return -ENOMEM;
+
+	if (!debugfs_create_bool("turbo", S_IRUGO, d, &opp->turbo))
+		return -ENOMEM;
+
+	if (!debugfs_create_bool("suspend", S_IRUGO, d, &opp->suspend))
+		return -ENOMEM;
+
+	if (!debugfs_create_ulong("rate_hz", S_IRUGO, d, &opp->rate))
+		return -ENOMEM;
+
+	if (!debugfs_create_ulong("u_volt_target", S_IRUGO, d, &opp->u_volt))
+		return -ENOMEM;
+
+	if (!debugfs_create_ulong("u_volt_min", S_IRUGO, d, &opp->u_volt_min))
+		return -ENOMEM;
+
+	if (!debugfs_create_ulong("u_volt_max", S_IRUGO, d, &opp->u_volt_max))
+		return -ENOMEM;
+
+	if (!debugfs_create_ulong("u_amp", S_IRUGO, d, &opp->u_amp))
+		return -ENOMEM;
+
+	if (!debugfs_create_ulong("clock_latency_ns", S_IRUGO, d,
+				  &opp->clock_latency_ns))
+		return -ENOMEM;
+
+	opp->dentry = d;
+	return 0;
+}
+
+static int device_opp_debug_create_dir(struct device_list_opp *list_dev,
+				       struct device_opp *dev_opp)
+{
+	const struct device *dev = list_dev->dev;
+	struct dentry *d;
+
+	opp_set_dev_name(dev, dev_opp->dentry_name);
+
+	/* Create device specific directory */
+	d = debugfs_create_dir(dev_opp->dentry_name, rootdir);
+	if (!d) {
+		dev_err(dev, "%s: Failed to create debugfs dir\n", __func__);
+		return -ENOMEM;
+	}
+
+	list_dev->dentry = d;
+	dev_opp->dentry = d;
+
+	return 0;
+}
+
+static int device_opp_debug_create_link(struct device_list_opp *list_dev,
+					struct device_opp *dev_opp)
+{
+	const struct device *dev = list_dev->dev;
+	char name[NAME_MAX];
+	struct dentry *d;
+
+	opp_set_dev_name(list_dev->dev, name);
+
+	/* Create device specific directory link */
+	d = debugfs_create_symlink(name, rootdir, dev_opp->dentry_name);
+	if (!d) {
+		dev_err(dev, "%s: Failed to create link\n", __func__);
+		return -ENOMEM;
+	}
+
+	list_dev->dentry = d;
+
+	return 0;
+}
+
+/**
+ * opp_debug_register - add a device opp node to the debugfs 'opp' directory
+ * @list_dev: list-dev pointer for device
+ * @dev_opp: the device-opp being added
+ *
+ * Dynamically adds device specific directory in debugfs 'opp' directory. If the
+ * device-opp is shared with other devices, then links will be created for all
+ * devices except the first.
+ *
+ * Return: 0 on success, otherwise negative error.
+ */
+int opp_debug_register(struct device_list_opp *list_dev,
+		       struct device_opp *dev_opp)
+{
+	if (!rootdir) {
+		pr_debug("%s: Uninitialized rootdir\n", __func__);
+		return -EINVAL;
+	}
+
+	if (dev_opp->dentry)
+		return device_opp_debug_create_link(list_dev, dev_opp);
+
+	return device_opp_debug_create_dir(list_dev, dev_opp);
+}
+
+static void opp_migrate_dentry(struct device_list_opp *list_dev,
+			       struct device_opp *dev_opp)
+{
+	struct device_list_opp *new_dev;
+	const struct device *dev;
+	struct dentry *dentry;
+
+	/* Look for next list-dev */
+	list_for_each_entry(new_dev, &dev_opp->dev_list, node)
+		if (new_dev != list_dev)
+			break;
+
+	/* new_dev is guaranteed to be valid here */
+	dev = new_dev->dev;
+	debugfs_remove_recursive(new_dev->dentry);
+
+	opp_set_dev_name(dev, dev_opp->dentry_name);
+
+	dentry = debugfs_rename(rootdir, list_dev->dentry, rootdir,
+				dev_opp->dentry_name);
+	if (!dentry) {
+		dev_err(dev, "%s: Failed to rename link from: %s to %s\n",
+			__func__, dev_name(list_dev->dev), dev_name(dev));
+		return;
+	}
+
+	new_dev->dentry = dentry;
+	dev_opp->dentry = dentry;
+}
+
+/**
+ * opp_debug_unregister - remove a device opp node from debugfs opp directory
+ * @list_dev: list-dev pointer for device
+ * @dev_opp: the device-opp being removed
+ *
+ * Dynamically removes device specific directory from debugfs 'opp' directory.
+ */
+void opp_debug_unregister(struct device_list_opp *list_dev,
+			  struct device_opp *dev_opp)
+{
+	if (list_dev->dentry == dev_opp->dentry) {
+		/* Move the real dentry object under another device */
+		if (!list_is_singular(&dev_opp->dev_list)) {
+			opp_migrate_dentry(list_dev, dev_opp);
+			goto out;
+		}
+		dev_opp->dentry = NULL;
+	}
+
+	debugfs_remove_recursive(list_dev->dentry);
+
+out:
+	list_dev->dentry = NULL;
+}
+
+static int __init opp_debug_init(void)
+{
+	/* Create /sys/kernel/debug/opp directory */
+	rootdir = debugfs_create_dir("opp", NULL);
+	if (!rootdir) {
+		pr_err("%s: Failed to create root directory\n", __func__);
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+core_initcall(opp_debug_init);