lkml.org 
[lkml]   [2011]   [Nov]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v3 5/5] clk: export tree topology and clk data via sysfs
Date
Introduces kobject support for the common struct clk, exports per-clk
data via read-only callbacks and models the clk tree topology in sysfs.

Also adds support for generating the clk tree in clk_init and migrating
nodes when input sources are switches in clk_set_parent.

Signed-off-by: Mike Turquette <mturquette@linaro.org>
---
drivers/clk/Kconfig | 10 +++
drivers/clk/Makefile | 1 +
drivers/clk/clk-sysfs.c | 199 +++++++++++++++++++++++++++++++++++++++++++++++
drivers/clk/clk.c | 5 +-
include/linux/clk.h | 36 ++++++++-
5 files changed, 248 insertions(+), 3 deletions(-)
create mode 100644 drivers/clk/clk-sysfs.c
diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
index ba7eb8c..8f8e7ac 100644
--- a/drivers/clk/Kconfig
+++ b/drivers/clk/Kconfig
@@ -19,3 +19,13 @@ config GENERIC_CLK_BASIC
help
Allow use of basic, single-function clock types. These
common definitions can be used across many platforms.
+
+config GENERIC_CLK_SYSFS
+ bool "Clock tree topology and debug info"
+ depends on EXPERIMENTAL && GENERIC_CLK
+ help
+ Creates clock tree represenation in sysfs. Directory names
+ and hierarchy represent clock names and tree structure,
+ respectively. Each directory exports clock rate, flags,
+ prepare_count and enable_count info as read-only for debug
+ purposes.
diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index 68b20a1..806a9999 100644
--- a/drivers/clk/Makefile
+++ b/drivers/clk/Makefile
@@ -2,3 +2,4 @@
obj-$(CONFIG_CLKDEV_LOOKUP) += clkdev.o
obj-$(CONFIG_GENERIC_CLK) += clk.o
obj-$(CONFIG_GENERIC_CLK_BASIC) += clk-basic.o
+obj-$(CONFIG_GENERIC_CLK_SYSFS) += clk-sysfs.o
diff --git a/drivers/clk/clk-sysfs.c b/drivers/clk/clk-sysfs.c
new file mode 100644
index 0000000..8ccf9e3
--- /dev/null
+++ b/drivers/clk/clk-sysfs.c
@@ -0,0 +1,199 @@
+/*
+ * Copyright (C) 2011 Linaro Ltd <mturquette@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.
+ *
+ * Clock tree topology and debug info for the common clock framework
+ */
+
+#include <linux/clk.h>
+#include <linux/kobject.h>
+#include <linux/sysfs.h>
+#include <linux/err.h>
+
+#define MAX_STRING_LENGTH 32
+
+static struct kobject *clk_kobj;
+LIST_HEAD(kobj_list);
+
+struct clk_attribute {
+ struct attribute attr;
+ ssize_t (*show)(struct clk *clk, char *buf);
+};
+
+static ssize_t clk_rate_show(struct clk *clk, char *buf)
+{
+ if (IS_ERR_OR_NULL(clk))
+ return -ENODEV;
+
+ return snprintf(buf, MAX_STRING_LENGTH, "%lu\n", clk->rate);
+}
+
+static ssize_t clk_flags_show(struct clk *clk, char *buf)
+{
+ if (IS_ERR_OR_NULL(clk))
+ return -ENODEV;
+
+ return snprintf(buf, MAX_STRING_LENGTH, "0x%lX\n", clk->flags);
+}
+
+static ssize_t clk_prepare_count_show(struct clk *clk, char *buf)
+{
+ if (IS_ERR_OR_NULL(clk))
+ return -ENODEV;
+
+ return snprintf(buf, MAX_STRING_LENGTH, "%d\n", clk->prepare_count);
+}
+
+static ssize_t clk_enable_count_show(struct clk *clk, char *buf)
+{
+ if (IS_ERR_OR_NULL(clk))
+ return -ENODEV;
+
+ return snprintf(buf, MAX_STRING_LENGTH, "%d\n", clk->enable_count);
+}
+
+static ssize_t clk_show(struct kobject *kobj, struct attribute *attr,
+ char *buf)
+{
+ struct clk *clk;
+ struct clk_attribute *clk_attr;
+ ssize_t ret = -EINVAL;
+
+ clk = container_of(kobj, struct clk, kobj);
+ clk_attr = container_of(attr, struct clk_attribute, attr);
+
+ if (!clk || !clk_attr)
+ goto out;
+
+ /* we don't do any locking for debug operations */
+
+ /* refcount++ */
+ kobject_get(&clk->kobj);
+
+ if (clk_attr->show)
+ ret = clk_attr->show(clk, buf);
+ else
+ ret = -EIO;
+
+ /* refcount-- */
+ kobject_put(&clk->kobj);
+
+out:
+ return ret;
+}
+
+static struct clk_attribute clk_rate = __ATTR_RO(clk_rate);
+static struct clk_attribute clk_flags = __ATTR_RO(clk_flags);
+static struct clk_attribute clk_prepare_count = __ATTR_RO(clk_prepare_count);
+static struct clk_attribute clk_enable_count = __ATTR_RO(clk_enable_count);
+
+static struct attribute *clk_default_attrs[] = {
+ &clk_rate.attr,
+ &clk_flags.attr,
+ &clk_prepare_count.attr,
+ &clk_enable_count.attr,
+ NULL,
+};
+
+static const struct sysfs_ops clk_ops = {
+ .show = clk_show,
+};
+
+static void clk_release(struct kobject *kobj)
+{
+ struct clk *clk;
+
+ clk = container_of(kobj, struct clk, kobj);
+
+ complete(&clk->kobj_unregister);
+}
+
+static struct kobj_type clk_ktype = {
+ .sysfs_ops = &clk_ops,
+ .default_attrs = clk_default_attrs,
+ .release = clk_release,
+};
+
+int clk_kobj_add(struct clk *clk)
+{
+ if (IS_ERR(clk))
+ return -EINVAL;
+
+ /*
+ * Some kobject trickery!
+ *
+ * We want to (ab)use the kobject infrastructure to track our
+ * tree topology for us, specifically the root clocks (which are
+ * otherwise not remembered in a global list).
+ *
+ * Unfortunately we might not be able to allocate memory yet
+ * when this path is hit. This pretty much rules out anything
+ * that looks or smells like kobject_add, since there are
+ * allocations for kobject->name and a dependency on sysfs being
+ * initialized.
+ *
+ * To get around this we initialize the kobjects and (ab)use
+ * struct kobject's list_head member, "entry". Later on we walk
+ * this list in clk_sysfs_tree_create() to make proper
+ * kobject_add calls once it is safe to do so.
+ *
+ * FIXME - this is starting to smell alot like clkdev (i.e.
+ * tracking the clocks in a list)
+ */
+
+ kobject_init(&clk->kobj, &clk_ktype);
+ list_add_tail(&clk->kobj.entry, &kobj_list);
+ return 0;
+}
+
+int clk_kobj_reparent(struct clk *clk, struct clk *parent)
+{
+ int ret;
+
+ if (!clk || !parent)
+ return -EINVAL;
+
+ ret = kobject_move(&clk->kobj, &parent->kobj);
+ if (ret)
+ pr_warning("%s: failed to reparent %s to %s in sysfs\n",
+ __func__, clk->name, parent->name);
+
+ return ret;
+}
+
+static int __init clk_sysfs_init(void)
+{
+ struct list_head *tmp;
+
+ clk_kobj = kobject_create_and_add("clk", NULL);
+
+ WARN_ON(!clk_kobj);
+
+ list_for_each(tmp, &kobj_list) {
+ struct kobject *kobj;
+ struct clk *clk;
+ struct kobject *parent_kobj = NULL;
+ int ret;
+
+ kobj = container_of(tmp, struct kobject, entry);
+
+ clk = container_of(kobj, struct clk, kobj);
+
+ /* assumes list is ordered */
+ if (clk->parent)
+ parent_kobj = &clk->parent->kobj;
+ else
+ parent_kobj = clk_kobj;
+
+ ret = kobject_add(kobj, parent_kobj, clk->name);
+ if (ret)
+ pr_warning("%s: failed to create sysfs entry for %s\n",
+ __func__, clk->name);
+ }
+
+ return 0;
+}
+late_initcall(clk_sysfs_init);
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 12c9994..85dabdb 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -436,7 +436,8 @@ void __clk_reparent(struct clk *clk, struct clk *new_parent)

clk->parent = new_parent;

- /* FIXME update sysfs clock topology */
+ /* update sysfs clock topology */
+ clk_kobj_reparent(clk, clk->parent);
}

/**
@@ -531,6 +532,8 @@ void clk_init(struct device *dev, struct clk *clk)
else
clk->rate = 0;

+ clk_kobj_add(clk);
+
mutex_unlock(&prepare_lock);

return;
diff --git a/include/linux/clk.h b/include/linux/clk.h
index 8ed354a..99337ca 100644
--- a/include/linux/clk.h
+++ b/include/linux/clk.h
@@ -14,8 +14,8 @@
#define __LINUX_CLK_H

#include <linux/kernel.h>
-
-#include <linux/kernel.h>
+#include <linux/kobject.h>
+#include <linux/completion.h>
#include <linux/errno.h>

struct device;
@@ -46,6 +46,10 @@ struct clk {
unsigned int prepare_count;
struct hlist_head children;
struct hlist_node child_node;
+#ifdef CONFIG_GENERIC_CLK_SYSFS
+ struct kobject kobj;
+ struct completion kobj_unregister;
+#endif
};

/**
@@ -177,6 +181,34 @@ int clk_register_gate(struct device *dev, const char *name, unsigned long flags,
*/
void clk_init(struct device *dev, struct clk *clk);

+#ifdef CONFIG_GENERIC_CLK_SYSFS
+/**
+ * clk_kobj_add - create a clk entry in sysfs
+ * @clk: clk to model in sysfs
+ *
+ * Create a directory in sysfs with the same name as clk. Also creates
+ * read-only entries for the common struct clk members (rate, flags,
+ * prepare_count & enable_count). The topology of the tree is
+ * represented by the sysfs directory structure itself.
+ */
+int clk_kobj_add(struct clk *clk);
+
+/**
+ * clk_kobj_reparent - reparent a clk entry in sysfs
+ * @clk: the child clk that is switching parents
+ * @parent: the new parent clk
+ *
+ * Simple call to kobject_move to keep sysfs up to date with the
+ * hardware clock topology
+ */
+int clk_kobj_reparent(struct clk *clk, struct clk *parent);
+#else
+static inline int clk_kobj_add(struct clk *clk)
+{ return 0; }
+static inline int clk_kobj_reparent(struct clk *clk, struct clk *parent)
+{ return 0; }
+#endif
+
#endif /* !CONFIG_GENERIC_CLK */

/**
--
1.7.4.1


\
 
 \ /
  Last update: 2011-11-22 02:47    [from the cache]
©2003-2011 Jasper Spaans