This patch adds debugfs support for boot constraints. This is how it
looks for a "vmmc-supply" constraint for the MMC device.

$ ls -R /sys/kernel/debug/boot_constraints/
/sys/kernel/debug/boot_constraints/:
f723d000.dwmmc0

/sys/kernel/debug/boot_constraints/f723d000.dwmmc0:
clk-ciu  pm-domain  supply-vmmc  supply-vmmcaux

/sys/kernel/debug/boot_constraints/f723d000.dwmmc0/clk-ciu:

/sys/kernel/debug/boot_constraints/f723d000.dwmmc0/pm-domain:

/sys/kernel/debug/boot_constraints/f723d000.dwmmc0/supply-vmmc:
u_volt_max  u_volt_min

/sys/kernel/debug/boot_constraints/f723d000.dwmmc0/supply-vmmcaux:
u_volt_max  u_volt_min

Tested-by: Rajendra Nayak <redacted>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 drivers/boot_constraints/clk.c    |  3 ++
 drivers/boot_constraints/core.c   | 60 +++++++++++++++++++++++++++++++++++++++
 drivers/boot_constraints/core.h   |  6 ++++
 drivers/boot_constraints/pm.c     | 11 +++++--
 drivers/boot_constraints/supply.c |  9 ++++++
 5 files changed, 87 insertions(+), 2 deletions(-)

diff --git a/drivers/boot_constraints/clk.c b/drivers/boot_constraints/clk.c
index b5b1d63c3e76..91b7b538ef32 100644
--- a/drivers/boot_constraints/clk.c
+++ b/drivers/boot_constraints/clk.c

@@ -49,6 +49,8 @@ int constraint_clk_add(struct constraint *constraint, void *data)
 	cclk->clk_info.name = kstrdup_const(clk_info->name, GFP_KERNEL);
 	constraint->private = cclk;
 
+	constraint_add_debugfs(constraint, clk_info->name);
+
 	return 0;
 
 put_clk:

@@ -63,6 +65,7 @@ void constraint_clk_remove(struct constraint *constraint)
 {
 	struct constraint_clk *cclk = constraint->private;
 
+	constraint_remove_debugfs(constraint);
 	kfree_const(cclk->clk_info.name);
 	clk_disable_unprepare(cclk->clk);
 	clk_put(cclk->clk);

diff --git a/drivers/boot_constraints/core.c b/drivers/boot_constraints/core.c
index f4d3520ddb04..707ffac690fc 100644
--- a/drivers/boot_constraints/core.c
+++ b/drivers/boot_constraints/core.c

@@ -24,6 +24,64 @@
 static LIST_HEAD(constraint_devices);
 static DEFINE_MUTEX(constraint_devices_mutex);
 
+/* Debugfs */
+
+static struct dentry *rootdir;
+
+static void constraint_device_add_debugfs(struct constraint_dev *cdev)
+{
+	struct device *dev = cdev->dev;
+
+	cdev->dentry = debugfs_create_dir(dev_name(dev), rootdir);
+}
+
+static void constraint_device_remove_debugfs(struct constraint_dev *cdev)
+{
+	debugfs_remove_recursive(cdev->dentry);
+}
+
+void constraint_add_debugfs(struct constraint *constraint, const char *suffix)
+{
+	struct device *dev = constraint->cdev->dev;
+	const char *prefix;
+	char name[NAME_MAX];
+
+	switch (constraint->type) {
+	case DEV_BOOT_CONSTRAINT_CLK:
+		prefix = "clk";
+		break;
+	case DEV_BOOT_CONSTRAINT_PM:
+		prefix = "pm";
+		break;
+	case DEV_BOOT_CONSTRAINT_SUPPLY:
+		prefix = "supply";
+		break;
+	default:
+		dev_err(dev, "%s: Constraint type (%d) not supported\n",
+			__func__, constraint->type);
+		return;
+	}
+
+	snprintf(name, NAME_MAX, "%s-%s", prefix, suffix);
+
+	constraint->dentry = debugfs_create_dir(name, constraint->cdev->dentry);
+}
+
+void constraint_remove_debugfs(struct constraint *constraint)
+{
+	debugfs_remove_recursive(constraint->dentry);
+}
+
+static int __init constraint_debugfs_init(void)
+{
+	/* Create /sys/kernel/debug/opp directory */
+	rootdir = debugfs_create_dir("boot_constraints", NULL);