clk: add DT clock binding support
Based on work 1st by Ben Herrenschmidt and Jeremy Kerr, then by Grant
Likely, this patch adds support to clk_get to allow drivers to retrieve
clock data from the device tree.
Platforms scan for clocks in DT with of_clk_init and a match table, and
the register a provider through of_clk_add_provider. The provider's
clk_src_get function will be called when a device references the
provider's OF node for a clock reference.
v6 (Rob Herring):
- Return error values instead of NULL to match clock framework
expectations
v5 (Rob Herring):
- Move from drivers/of into common clock subsystem
- Squashed "dt/clock: add a simple provider get function" and
"dt/clock: add function to get parent clock name"
- Rebase to 3.4-rc1
- Drop CONFIG_OF_CLOCK and just use CONFIG_OF
- Add missing EXPORT_SYMBOL to various functions
- s/clock-output-name/clock-output-names/
- Define that fixed-clock binding is a single output
v4 (Rob Herring):
- Rework for common clk subsystem
- Add of_clk_get_parent_name function
v3: - Clarified documentation
v2: - fixed errant ';' causing compile error
- Editorial fixes from Shawn Guo
- merged in adding lookup to clkdev
- changed property names to match established convention. After
working with the binding a bit it really made more sense to follow the
lead of 'reg', 'gpios' and 'interrupts' by making the input simply
'clocks' & 'clock-names' instead of 'clock-input-*', and to only use
clock-output* for the producer nodes. (Sorry Shawn, this will mean
you need to change some code, but it should be trivial)
- Add ability to inherit clocks from parent nodes by using an empty
'clock-ranges' property. Useful for busses. I could use some feedback
on the new property name, 'clock-ranges' doesn't feel right to me.
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Reviewed-by: Shawn Guo <shawn.guo@freescale.com>
Cc: Sascha Hauer <kernel@pengutronix.de>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
diff --git a/drivers/clk/clkdev.c b/drivers/clk/clkdev.c
index c535cf8..20649b3 100644
--- a/drivers/clk/clkdev.c
+++ b/drivers/clk/clkdev.c
@@ -19,10 +19,80 @@
#include <linux/mutex.h>
#include <linux/clk.h>
#include <linux/clkdev.h>
+#include <linux/of.h>
static LIST_HEAD(clocks);
static DEFINE_MUTEX(clocks_mutex);
+#ifdef CONFIG_OF
+struct clk *of_clk_get(struct device_node *np, int index)
+{
+ struct of_phandle_args clkspec;
+ struct clk *clk;
+ int rc;
+
+ if (index < 0)
+ return ERR_PTR(-EINVAL);
+
+ rc = of_parse_phandle_with_args(np, "clocks", "#clock-cells", index,
+ &clkspec);
+ if (rc)
+ return ERR_PTR(rc);
+
+ clk = of_clk_get_from_provider(&clkspec);
+ of_node_put(clkspec.np);
+ return clk;
+}
+EXPORT_SYMBOL(of_clk_get);
+
+/**
+ * of_clk_get_by_name() - Parse and lookup a 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.
+ */
+struct clk *of_clk_get_by_name(struct device_node *np, const char *name)
+{
+ struct clk *clk = ERR_PTR(-ENOENT);
+
+ /* Walk up the tree of devices looking for a clock that matches */
+ while (np) {
+ int index = 0;
+
+ /*
+ * For named clocks, first look up the name in the
+ * "clock-names" property. If it cannot be found, then
+ * index will be an error code, and of_clk_get() will fail.
+ */
+ if (name)
+ index = of_property_match_string(np, "clock-names", name);
+ clk = of_clk_get(np, index);
+ if (!IS_ERR(clk))
+ break;
+ else if (name && index >= 0) {
+ pr_err("ERROR: could not get clock %s:%s(%i)\n",
+ np->full_name, name ? name : "", index);
+ return clk;
+ }
+
+ /*
+ * No matching clock found on this node. If the parent node
+ * has a "clock-ranges" property, then we can try one of its
+ * clocks.
+ */
+ np = np->parent;
+ if (np && !of_get_property(np, "clock-ranges", NULL))
+ break;
+ }
+
+ return clk;
+}
+EXPORT_SYMBOL(of_clk_get_by_name);
+#endif
+
/*
* Find the correct struct clk for the device and connection ID.
* We do slightly fuzzy matching here:
@@ -83,6 +153,13 @@
struct clk *clk_get(struct device *dev, const char *con_id)
{
const char *dev_id = dev ? dev_name(dev) : NULL;
+ struct clk *clk;
+
+ if (dev) {
+ clk = of_clk_get_by_name(dev->of_node, con_id);
+ if (clk && __clk_get(clk))
+ return clk;
+ }
return clk_get_sys(dev_id, con_id);
}