[PATCH 2/2] Driver for user access to internal clocks

Davide Rizzo
2009-02-09T17:54:28Z

This is a proposal for adding 2 functions to clk interface to allow higher
level drivers to enumerate and list all clocks, and to modify clk_get
to accept device specific clk names in the form "name.id"
There is also the implementation for Samsung S3C24xx platform.

Signed-off-by: Davide Rizzo <elpa.rizzo@gmail.com>
---diff -urpN linux-2.6.29-rc2/arch/arm/plat-s3c/clock.c
linux-2.6.29-rc2.elpa/arch/arm/plat-s3c/clock.c
--- linux-2.6.29-rc2/arch/arm/plat-s3c/clock.c 2009-01-17
11:32:38.000000000 +0100
+++ linux-2.6.29-rc2.elpa/arch/arm/plat-s3c/clock.c 2009-01-28
19:32:08.000000000 +0100
@@ -69,11 +69,19 @@ static int clk_null_enable(struct clk *c

struct clk *clk_get(struct device *dev, const char *id)
{
+ long idno;
+ char *name = (char *)id;
+ char *dotpos = strrchr(id, '.');
struct clk *p;
struct clk *clk = ERR_PTR(-ENOENT);
- int idno;

- if (dev == NULL || dev->bus != &platform_bus_type)
+ if (dotpos) {
+ int err = strict_strtol(dotpos + 1, 10, &idno);
+ if (err)
+ return ERR_PTR(err);
+ name = kstrdup(id, GFP_KERNEL);
+ name[dotpos - id] = '\0';
+ } else if (dev == NULL || dev->bus != &platform_bus_type)
idno = -1;
else
idno = to_platform_device(dev)->id;
@@ -82,7 +90,7 @@ struct clk *clk_get(struct device *dev,

list_for_each_entry(p, &clocks, list) {
if (p->id == idno &&
- strcmp(id, p->name) == 0 &&
+ strcmp(name, p->name) == 0 &&
try_module_get(p->owner)) {
clk = p;
break;
@@ -94,7 +102,7 @@ struct clk *clk_get(struct device *dev,

if (IS_ERR(clk)) {
list_for_each_entry(p, &clocks, list) {
- if (p->id == -1 && strcmp(id, p->name) == 0 &&
+ if (p->id == -1 && strcmp(name, p->name) == 0 &&
try_module_get(p->owner)) {
clk = p;
break;
@@ -103,6 +111,8 @@ struct clk *clk_get(struct device *dev,
}

spin_unlock(&clocks_lock);
+ if (dotpos)
+ kfree(name);
return clk;
}

@@ -222,6 +232,42 @@ EXPORT_SYMBOL(clk_set_rate);
EXPORT_SYMBOL(clk_get_parent);
EXPORT_SYMBOL(clk_set_parent);

+int clk_for_each(int(*fn)(struct clk *, void *), void *data)
+ {
+ struct clk *clk;
+ int ret = 0;
+
+ list_for_each_entry(clk, &clocks, list)
+ {
+ ret = fn(clk, data);
+ if (ret)
+ break;
+ }
+ return ret;
+}
+EXPORT_SYMBOL(clk_for_each);
+
+/* Returned pointer must be deallocated with kfree() */
+const char *clk_get_name(struct clk *clk)
+{
+ char *s;
+ int len;
+
+ if (IS_ERR(clk))
+ return ERR_PTR(-EINVAL);
+
+ len = strlen(clk->name) + 8;
+ s = kmalloc(len, GFP_KERNEL);
+ if (!s)
+ return ERR_PTR(-ENOMEM);
+ if (clk->id == -1)
+ strlcpy(s, clk->name, len);
+ else if (snprintf(s, len, "%s.%d", clk->name, clk->id) > len)
+ s[len - 1] = '\0';
+ return s;
+}
+EXPORT_SYMBOL(clk_get_name);
+
/* base clocks */

static int clk_default_setrate(struct clk *clk, unsigned long rate)
diff -urpN linux-2.6.29-rc2/include/linux/clk.h
linux-2.6.29-rc2.elpa/include/linux/clk.h
--- linux-2.6.29-rc2/include/linux/clk.h 2008-12-25
00:26:37.000000000 +0100
+++ linux-2.6.29-rc2.elpa/include/linux/clk.h 2009-01-28
19:21:43.000000000 +0100
@@ -125,4 +125,22 @@ int clk_set_parent(struct clk *clk, stru
*/
struct clk *clk_get_parent(struct clk *clk);

+/**
+ * clk_for_each - calls fn, iterating between registered clocks
+ * @fn: function to be called, passing each clk structure in 1st argument
+ * @data: 2nd argument to pass to fn function
+ *
+ * Returns 0 or the called fn return code if != 0
+ */
+int clk_for_each(int(*fn)(struct clk *, void *), void *data);
+
+/**
+ * clk_name - get clock name
+ * @clk: clock source
+ *
+ * Returns clock's name that must be deallocated with kfree(), or valid
+ * IS_ERR() condition containing errno.
+ */
+const char *clk_get_name(struct clk *clk);
+
#endif