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authorShawn Guo <shawn.guo@linaro.org>2012-09-05 01:09:12 +0200
committerRafael J. Wysocki <rjw@sisk.pl>2012-09-09 22:06:33 +0200
commitb496dfbc94ab86f970ef0167eaabe51f930aa5fb (patch)
tree3ce7bdb6847fbcff3f46935ebc5b5c17da23d31d
parentec971ea5f2426a0bf9d5cca9a103743918c12978 (diff)
PM / OPP: Initialize OPP table from device tree
With a lot of devices booting from device tree nowadays, it requires that OPP table can be initialized from device tree. The patch adds a helper function of_init_opp_table together with a binding doc for that purpose. Signed-off-by: Shawn Guo <shawn.guo@linaro.org> Acked-by: Rob Herring <rob.herring@calxeda.com> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
-rw-r--r--Documentation/devicetree/bindings/power/opp.txt25
-rw-r--r--drivers/base/power/opp.c47
-rw-r--r--include/linux/opp.h8
3 files changed, 80 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/power/opp.txt b/Documentation/devicetree/bindings/power/opp.txt
new file mode 100644
index 00000000000..74499e5033f
--- /dev/null
+++ b/Documentation/devicetree/bindings/power/opp.txt
@@ -0,0 +1,25 @@
+* Generic OPP Interface
+
+SoCs have a standard set of tuples consisting of frequency and
+voltage pairs that the device will support per voltage domain. These
+are called Operating Performance Points or OPPs.
+
+Properties:
+- operating-points: An array of 2-tuples items, and each item consists
+ of frequency and voltage like <freq-kHz vol-uV>.
+ freq: clock frequency in kHz
+ vol: voltage in microvolt
+
+Examples:
+
+cpu@0 {
+ compatible = "arm,cortex-a9";
+ reg = <0>;
+ next-level-cache = <&L2>;
+ operating-points = <
+ /* kHz uV */
+ 792000 1100000
+ 396000 950000
+ 198000 850000
+ >;
+};
diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c
index ac993eafec8..d9468642fc4 100644
--- a/drivers/base/power/opp.c
+++ b/drivers/base/power/opp.c
@@ -22,6 +22,7 @@
#include <linux/rculist.h>
#include <linux/rcupdate.h>
#include <linux/opp.h>
+#include <linux/of.h>
/*
* Internal data structure organization with the OPP layer library is as
@@ -674,3 +675,49 @@ struct srcu_notifier_head *opp_get_notifier(struct device *dev)
return &dev_opp->head;
}
+
+#ifdef CONFIG_OF
+/**
+ * of_init_opp_table() - Initialize opp table from device tree
+ * @dev: device pointer used to lookup device OPPs.
+ *
+ * Register the initial OPP table with the OPP library for given device.
+ */
+int of_init_opp_table(struct device *dev)
+{
+ const struct property *prop;
+ const __be32 *val;
+ int nr;
+
+ prop = of_find_property(dev->of_node, "operating-points", NULL);
+ if (!prop)
+ return -ENODEV;
+ if (!prop->value)
+ return -ENODATA;
+
+ /*
+ * Each OPP is a set of tuples consisting of frequency and
+ * voltage like <freq-kHz vol-uV>.
+ */
+ nr = prop->length / sizeof(u32);
+ if (nr % 2) {
+ dev_err(dev, "%s: Invalid OPP list\n", __func__);
+ return -EINVAL;
+ }
+
+ val = prop->value;
+ while (nr) {
+ unsigned long freq = be32_to_cpup(val++) * 1000;
+ unsigned long volt = be32_to_cpup(val++);
+
+ if (opp_add(dev, freq, volt)) {
+ dev_warn(dev, "%s: Failed to add OPP %ld\n",
+ __func__, freq);
+ continue;
+ }
+ nr -= 2;
+ }
+
+ return 0;
+}
+#endif
diff --git a/include/linux/opp.h b/include/linux/opp.h
index 2a4e5faee90..214e0ebcb84 100644
--- a/include/linux/opp.h
+++ b/include/linux/opp.h
@@ -48,6 +48,14 @@ int opp_disable(struct device *dev, unsigned long freq);
struct srcu_notifier_head *opp_get_notifier(struct device *dev);
+#ifdef CONFIG_OF
+int of_init_opp_table(struct device *dev);
+#else
+static inline int of_init_opp_table(struct device *dev)
+{
+ return -EINVAL;
+}
+#endif /* CONFIG_OF */
#else
static inline unsigned long opp_get_voltage(struct opp *opp)
{