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Subject[RFC PATCH 3/5] of: add clock providers
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Date
From: Jeremy Kerr <jeremy.kerr@canonical.com>

Based on work by Ben Herrenschmidt, this patch adds an of_clk_get
function to allow platforms to retrieve clock data from the device tree.

Platform register a provider through of_clk_add_provider, which will be
called when a device references the provider's OF node for a clock
reference.

Signed-off-by: Jeremy Kerr <jeremy.kerr@canonical.com>
[grant.likely@secretlab.ca: fix Kconfig conflict]
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
---
drivers/of/Kconfig | 5 ++
drivers/of/Makefile | 1
drivers/of/clock.c | 134 ++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/of_clk.h | 36 +++++++++++++
4 files changed, 176 insertions(+), 0 deletions(-)
create mode 100644 drivers/of/clock.c
create mode 100644 include/linux/of_clk.h

diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig
index 3c6e100..6650583 100644
--- a/drivers/of/Kconfig
+++ b/drivers/of/Kconfig
@@ -69,4 +69,9 @@ config OF_MDIO
help
OpenFirmware MDIO bus (Ethernet PHY) accessors

+config OF_CLOCK
+ def_bool y
+ depends on HAVE_CLK
+ help
+ OpenFirmware clock accessors
endmenu # OF
diff --git a/drivers/of/Makefile b/drivers/of/Makefile
index 3ab21a0..c378c7b 100644
--- a/drivers/of/Makefile
+++ b/drivers/of/Makefile
@@ -5,6 +5,7 @@ obj-$(CONFIG_OF_ADDRESS) += address.o
obj-$(CONFIG_OF_IRQ) += irq.o
obj-$(CONFIG_OF_DEVICE) += device.o platform.o
obj-$(CONFIG_OF_GPIO) += gpio.o
+obj-$(CONFIG_OF_CLOCK) += clock.o
obj-$(CONFIG_OF_I2C) += of_i2c.o
obj-$(CONFIG_OF_NET) += of_net.o
obj-$(CONFIG_OF_SPI) += of_spi.o
diff --git a/drivers/of/clock.c b/drivers/of/clock.c
new file mode 100644
index 0000000..3e2b221
--- /dev/null
+++ b/drivers/of/clock.c
@@ -0,0 +1,134 @@
+/*
+ * Clock infrastructure for device tree platforms
+ */
+
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/errno.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_clk.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/device.h>
+
+struct of_clk_provider {
+ struct list_head link;
+ struct device_node *node;
+
+ /* Return NULL if no such clock output */
+ struct clk *(*get)(struct device_node *np,
+ const char *output_id, void *data);
+ void *data;
+};
+
+static LIST_HEAD(of_clk_providers);
+static DEFINE_MUTEX(of_clk_lock);
+
+int of_clk_add_provider(struct device_node *np,
+ struct clk *(*clk_src_get)(struct device_node *np,
+ const char *output_id,
+ void *data),
+ void *data)
+{
+ struct of_clk_provider *cp;
+
+ cp = kzalloc(sizeof(struct of_clk_provider), GFP_KERNEL);
+ if (!cp)
+ return -ENOMEM;
+
+ cp->node = of_node_get(np);
+ cp->data = data;
+ cp->get = clk_src_get;
+
+ mutex_lock(&of_clk_lock);
+ list_add(&cp->link, &of_clk_providers);
+ mutex_unlock(&of_clk_lock);
+ pr_debug("Added clock from %s\n", np->full_name);
+
+ return 0;
+}
+
+void of_clk_del_provider(struct device_node *np,
+ struct clk *(*clk_src_get)(struct device_node *np,
+ const char *output_id,
+ void *data),
+ void *data)
+{
+ struct of_clk_provider *cp, *tmp;
+
+ mutex_lock(&of_clk_lock);
+ list_for_each_entry_safe(cp, tmp, &of_clk_providers, link) {
+ if (cp->node == np && cp->get == clk_src_get &&
+ cp->data == data) {
+ list_del(&cp->link);
+ of_node_put(cp->node);
+ kfree(cp);
+ break;
+ }
+ }
+ mutex_unlock(&of_clk_lock);
+}
+
+static struct clk *__of_clk_get_from_provider(struct device_node *np, const char *clk_output)
+{
+ struct of_clk_provider *provider;
+ struct clk *clk = NULL;
+
+ /* Check if we have such a provider in our array */
+ mutex_lock(&of_clk_lock);
+ list_for_each_entry(provider, &of_clk_providers, link) {
+ if (provider->node == np)
+ clk = provider->get(np, clk_output, provider->data);
+ if (clk)
+ break;
+ }
+ mutex_unlock(&of_clk_lock);
+
+ return clk;
+}
+
+struct clk *of_clk_get(struct device *dev, const char *id)
+{
+ struct device_node *provnode;
+ u32 provhandle;
+ int sz;
+ struct clk *clk;
+ char prop_name[32]; /* 32 is max size of property name */
+ const void *prop;
+
+ dev_dbg(dev, "Looking up %s-clock from device tree\n", id);
+
+ snprintf(prop_name, 32, "%s-clock", id ? id : "bus");
+ prop = of_get_property(dev->of_node, prop_name, &sz);
+ if (!prop || sz < 4)
+ return NULL;
+
+ /* Extract the phandle from the start of the property value */
+ provhandle = be32_to_cpup(prop);
+ prop += 4;
+ sz -= 4;
+
+ /* Make sure the clock name is properly terminated and within the
+ * size of the property. */
+ if (strlen(prop) + 1 > sz)
+ return NULL;
+
+ /* Find the clock provider node; check if it is registered as a
+ * provider, and ask it for the relevant clk structure */
+ provnode = of_find_node_by_phandle(provhandle);
+ if (!provnode) {
+ pr_warn("%s: %s property in node %s references invalid phandle",
+ __func__, prop_name, dev->of_node->full_name);
+ return NULL;
+ }
+ clk = __of_clk_get_from_provider(provnode, prop);
+ if (clk)
+ dev_dbg(dev, "Using clock from %s\n", provnode->full_name);
+
+ of_node_put(provnode);
+
+ return clk;
+}
+
diff --git a/include/linux/of_clk.h b/include/linux/of_clk.h
new file mode 100644
index 0000000..c2f6b5a
--- /dev/null
+++ b/include/linux/of_clk.h
@@ -0,0 +1,36 @@
+/*
+ * Clock infrastructure for device tree platforms
+ */
+#ifndef __OF_CLK_H
+#define __OF_CLK_H
+
+struct device;
+struct clk;
+
+#ifdef CONFIG_OF_CLOCK
+
+struct device_node;
+
+int of_clk_add_provider(struct device_node *np,
+ struct clk *(*clk_src_get)(struct device_node *np,
+ const char *output_id,
+ void *data),
+ void *data);
+
+void of_clk_del_provider(struct device_node *np,
+ struct clk *(*clk_src_get)(struct device_node *np,
+ const char *output_id,
+ void *data),
+ void *data);
+
+struct clk *of_clk_get(struct device *dev, const char *id);
+
+#else
+static inline struct clk *of_clk_get(struct device *dev, const char *id)
+{
+ return NULL;
+}
+#endif
+
+#endif /* __OF_CLK_H */
+


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