[PATCH RFC v3 2/2] clk: Add handling of clk parent and rate assigned from DT

Sylwester Nawrocki
2014-03-27T12:16:19Z

This function adds a helper function to configure clock parents and rates
as specified in clock-parents, clock-rates DT properties for a consumer
device and a call to it before driver is bound to a device.

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
---
Changes since v2:
- edited in clock-bindings.txt, added note about 'assigned-clocks'
subnode which may be used to specify "global" clocks configuration
at a clock provider node,
- moved of_clk_device_setup() function declaration from clk-provider.h
to clk-conf.h so required function stubs are available when
CONFIG_COMMON_CLK is not enabled,

Changes since v1:
- the helper function to parse and set assigned clock parents and
rates made public so it is available to clock providers to call
directly;
- dropped the platform bus notification and call of_clk_device_setup()
is is now called from the driver core, rather than from the
notification callback;
- s/of_clk_get_list_entry/of_clk_get_by_property.
---
.../devicetree/bindings/clock/clock-bindings.txt | 26 ++++++
drivers/base/dd.c | 7 ++
drivers/clk/Makefile | 1 +
drivers/clk/clk-conf.c | 87 ++++++++++++++++++++
drivers/clk/clk.c | 10 ++-
include/linux/clk/clk-conf.h | 19 +++++
6 files changed, 149 insertions(+), 1 deletion(-)
create mode 100644 drivers/clk/clk-conf.c
create mode 100644 include/linux/clk/clk-conf.h

diff --git a/Documentation/devicetree/bindings/clock/clock-bindings.txt b/Documentation/devicetree/bindings/clock/clock-bindings.txt
index 7c52c29..b452f80 100644
--- a/Documentation/devicetree/bindings/clock/clock-bindings.txt
+++ b/Documentation/devicetree/bindings/clock/clock-bindings.txt
@@ -115,3 +115,29 @@ clock signal, and a UART.
("pll" and "pll-switched").
* The UART has its baud clock connected the external oscillator and its
register clock connected to the PLL clock (the "pll-switched" signal)
+
+==Assigned clock parents and rates==
+
+Some platforms require static initial configuration of parts of the clocks
+controller. Such a configuration can be specified in a clock consumer node
+through clock-parents and clock-rates DT properties. The former should contain
+a list of parent clocks in form of phandle and clock specifier pairs, the
+latter the list of assigned clock frequency values (one cell each).
+
+ uart at a000 {
+ compatible = "fsl,imx-uart";
+ reg = <0xa000 0x1000>;
+ ...
+ clocks = <&clkcon 0>, <&clkcon 3>;
+ clock-names = "baud", "mux";
+
+ clock-parents = <0>, <&pll 1>;
+ clock-rates = <460800>;
+ };
+
+In this example the pll is set as parent of "mux" clock and frequency of "baud"
+clock is specified as 460800 Hz.
+
+For clocks which are not directly connected to any consumer device similarly
+clocks, clock-parents and/or clock-rates properties should be specified in
+assigned-clocks subnode of a clock controller DT node.
diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 0605176..4c633e7 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -25,6 +25,7 @@
#include <linux/async.h>
#include <linux/pm_runtime.h>
#include <linux/pinctrl/devinfo.h>
+#include <linux/clk/clk-conf.h>

#include "base.h"
#include "power/power.h"
@@ -278,6 +279,12 @@ static int really_probe(struct device *dev, struct device_driver *drv)
if (ret)
goto probe_failed;

+ if (dev->of_node) {
+ ret = of_clk_device_init(dev->of_node);
+ if (ret)
+ goto probe_failed;
+ }
+
if (driver_sysfs_add(dev)) {
printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
__func__, dev_name(dev));
diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index a367a98..c720e4b 100644
--- a/drivers/clk/Makefile
+++ b/drivers/clk/Makefile
@@ -8,6 +8,7 @@ obj-$(CONFIG_COMMON_CLK) += clk-fixed-rate.o
obj-$(CONFIG_COMMON_CLK) += clk-gate.o
obj-$(CONFIG_COMMON_CLK) += clk-mux.o
obj-$(CONFIG_COMMON_CLK) += clk-composite.o
+obj-$(CONFIG_COMMON_CLK) += clk-conf.o

# hardware specific clock types
# please keep this section sorted lexicographically by file/directory path name
diff --git a/drivers/clk/clk-conf.c b/drivers/clk/clk-conf.c
new file mode 100644
index 0000000..a2e992e
--- /dev/null
+++ b/drivers/clk/clk-conf.c
@@ -0,0 +1,87 @@
+/*
+ * Copyright (C) 2014 Samsung Electronics Co., Ltd.
+ * Sylwester Nawrocki <s.nawrocki@samsung.com>
+ *
+ * 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.
+ */
+
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/device.h>
+#include <linux/of.h>
+#include <linux/printk.h>
+
+/**
+ * of_clk_device_init() - parse and set clk configuration assigned to a device
+ * @node: device node to apply the configuration for
+ *
+ * This function parses 'clock-parents' and 'clock-rates' properties and sets
+ * any specified clock parents and rates.
+ */
+int of_clk_device_init(struct device_node *node)
+{
+ struct property *prop;
+ const __be32 *cur;
+ int rc, index, num_parents;
+ struct clk *clk, *pclk;
+ u32 rate;
+
+ num_parents = of_count_phandle_with_args(node, "clock-parents",
+ "#clock-cells");
+ if (num_parents == -EINVAL)
+ pr_err("clk: Invalid value of clock-parents property at %s\n",
+ node->full_name);
+
+ for (index = 0; index < num_parents; index++) {
+ pclk = of_clk_get_by_property(node, "clock-parents", index);
+ if (IS_ERR(pclk)) {
+ /* skip empty (null) phandles */
+ if (PTR_ERR(pclk) == -ENOENT)
+ continue;
+
+ pr_warn("clk: couldn't get parent clock %d for %s\n",
+ index, node->full_name);
+ return PTR_ERR(pclk);
+ }
+
+ clk = of_clk_get(node, index);
+ if (IS_ERR(clk)) {
+ pr_warn("clk: couldn't get clock %d for %s\n",
+ index, node->full_name);
+ return PTR_ERR(clk);
+ }
+
+ rc = clk_set_parent(clk, pclk);
+ if (rc < 0)
+ pr_err("clk: failed to reparent %s to %s: %d\n",
+ __clk_get_name(clk), __clk_get_name(pclk), rc);
+ else
+ pr_debug("clk: set %s as parent of %s\n",
+ __clk_get_name(pclk), __clk_get_name(clk));
+ }
+
+ index = 0;
+ of_property_for_each_u32(node, "clock-rates", prop, cur, rate) {
+ if (rate) {
+ clk = of_clk_get(node, index);
+ if (IS_ERR(clk)) {
+ pr_warn("clk: couldn't get clock %d for %s\n",
+ index, node->full_name);
+ return PTR_ERR(clk);
+ }
+
+ rc = clk_set_rate(clk, rate);
+ if (rc < 0)
+ pr_err("clk: couldn't set %s clock rate: %d\n",
+ __clk_get_name(clk), rc);
+ else
+ pr_debug("clk: set rate of clock %s to %lu\n",
+ __clk_get_name(clk), clk_get_rate(clk));
+ }
+ index++;
+ }
+
+ return 0;
+}
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 29dc1e7..240d776 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -10,6 +10,7 @@
*/

#include <linux/clk-private.h>
+#include <linux/clk/clk-conf.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>
@@ -2604,7 +2605,15 @@ void __init of_clk_init(const struct of_device_id *matches)
list_for_each_entry_safe(clk_provider, next,
&clk_provider_list, node) {
if (force || parent_ready(clk_provider->np)) {
+
clk_provider->clk_init_cb(clk_provider->np);
+
+ /* Set any assigned clock parents and rates */
+ np = of_get_child_by_name(clk_provider->np,
+ "assigned-clocks");
+ if (np)
+ of_clk_device_init(np);
+
list_del(&clk_provider->node);
kfree(clk_provider);
is_init_done = true;
@@ -2619,7 +2628,6 @@ void __init of_clk_init(const struct of_device_id *matches)
*/
if (!is_init_done)
force = true;
-
}
}
#endif
diff --git a/include/linux/clk/clk-conf.h b/include/linux/clk/clk-conf.h
new file mode 100644
index 0000000..f06b1c2
--- /dev/null
+++ b/include/linux/clk/clk-conf.h
@@ -0,0 +1,19 @@
+/*
+ * Copyright (C) 2014 Samsung Electronics Co., Ltd.
+ * Sylwester Nawrocki <s.nawrocki@samsung.com>
+ *
+ * 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.
+ */
+
+struct device_node;
+
+#if defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK)
+int of_clk_device_init(struct device_node *node);
+#else
+int of_clk_device_init(struct device_node *node)
+{
+ return 0;
+}
+#endif
--
1.7.9.5