Quite a few drivers get an optional clock, e.g. a clock required
to access peripheral's registers that is always enabled on some
devices.
This function behaves the same as of_clk_get_by_name() except that
it will return NULL instead of -ENOENT. This makes error checking
for users easier and allows clk_prepare_enable, etc to be called
on the returned reference without additional checks.
Signed-off-by: Phil Edworthy <phil.edwor...@renesas.com>
---
drivers/clk/clkdev.c | 34 ++++++++++++++++++++++++++++++----
include/linux/clk.h | 1 +
2 files changed, 31 insertions(+), 4 deletions(-)
diff --git a/drivers/clk/clkdev.c b/drivers/clk/clkdev.c
index 9ab3db8..c1b7262 100644
--- a/drivers/clk/clkdev.c
+++ b/drivers/clk/clkdev.c
@@ -54,7 +54,8 @@ EXPORT_SYMBOL(of_clk_get);
static struct clk *__of_clk_get_by_name(struct device_node *np,
const char *dev_id,
- const char *name)
+ const char *name,
+ bool optional)
{
struct clk *clk = ERR_PTR(-ENOENT);
@@ -73,6 +74,8 @@ static struct clk *__of_clk_get_by_name(struct device_node
*np,
if (!IS_ERR(clk)) {
break;
} else if (name && index >= 0) {
+ if (optional && PTR_ERR(clk) == -ENOENT)
+ clk = NULL;
if (PTR_ERR(clk) != -EPROBE_DEFER)
pr_err("ERROR: could not get clock
%pOF:%s(%i)\n",
np, name ? name : "", index);
@@ -106,15 +109,38 @@ struct clk *of_clk_get_by_name(struct device_node *np,
const char *name)
if (!np)
return ERR_PTR(-ENOENT);
- return __of_clk_get_by_name(np, np->full_name, name);
+ return __of_clk_get_by_name(np, np->full_name, name, false);
}
EXPORT_SYMBOL(of_clk_get_by_name);
+/**
+ * of_clk_get_by_name_optional() - Parse and lookup an optional clock
referenced
+ * by a device node
+ * @np: pointer to clock consumer node
+ * @name: name of consumer's clock input, or NULL for the first clock reference
+ *
+ * This function parses the clocks and clock-names properties,
+ * and uses them to look up the struct clk from the registered list of clock
+ * providers.
+ * It behaves the same as of_clk_get_by_name(), except when no clock is found.
+ * In this case, instead of returning -ENOENT, it returns NULL.
+ */
+struct clk *of_clk_get_by_name_optional(struct device_node *np,
+ const char *name)
+{
+ if (!np)
+ return ERR_PTR(-ENOENT);
+
+ return __of_clk_get_by_name(np, np->full_name, name, true);
+}
+EXPORT_SYMBOL(of_clk_get_by_name_optional);
+
#else /* defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK) */
static struct clk *__of_clk_get_by_name(struct device_node *np,
const char *dev_id,
- const char *name)
+ const char *name,
+ bool optional)
{
return ERR_PTR(-ENOENT);
}
@@ -197,7 +223,7 @@ struct clk *clk_get(struct device *dev, const char *con_id)
struct clk *clk;
if (dev && dev->of_node) {
- clk = __of_clk_get_by_name(dev->of_node, dev_id, con_id);
+ clk = __of_clk_get_by_name(dev->of_node, dev_id, con_id, false);
if (!IS_ERR(clk) || PTR_ERR(clk) == -EPROBE_DEFER)
return clk;
}
diff --git a/include/linux/clk.h b/include/linux/clk.h
index 4f750c4..8cb5455 100644
--- a/include/linux/clk.h
+++ b/include/linux/clk.h
@@ -777,6 +777,7 @@ static inline void clk_bulk_disable_unprepare(int num_clks,
#if defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK)
struct clk *of_clk_get(struct device_node *np, int index);
struct clk *of_clk_get_by_name(struct device_node *np, const char *name);
+struct clk *of_clk_get_by_name_optional(struct device_node *np, const char
*name);
struct clk *of_clk_get_from_provider(struct of_phandle_args *clkspec);
#else
static inline struct clk *of_clk_get(struct device_node *np, int index)
--
2.7.4
