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@xxxxxxxxxx>
---
Documentation/devicetree/bindings/power/opp.txt | 25 +++++++++
drivers/base/power/opp.c | 65 +++++++++++++++++++++++
include/linux/opp.h | 8 +++
3 files changed, 98 insertions(+), 0 deletions(-)
create mode 100644 Documentation/devicetree/bindings/power/opp.txt
diff --git a/Documentation/devicetree/bindings/power/opp.txt b/Documentation/devicetree/bindings/power/opp.txt
new file mode 100644
index 0000000..2238520
--- /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 3-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 ac993ea..1bf1be8 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 +675,67 @@ 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)
+{
+ struct device_node *np = dev->of_node;
+ const char *propname = "operating-points";
+ const struct property *pp;
+ u32 *opp;
+ int ret, i, nr;
+
+ pp = of_find_property(np, propname, NULL);
+ if (!pp) {
+ dev_err(dev, "%s: Unable to find property", __func__);
+ return -ENODEV;
+ }
+
+ opp = kzalloc(pp->length, GFP_KERNEL);
+ if (!opp) {
+ dev_err(dev, "%s: Unable to allocate array\n", __func__);
+ return -ENOMEM;
+ }
+
+ nr = pp->length / sizeof(u32);
+ ret = of_property_read_u32_array(np, propname, opp, nr);
+ if (ret) {
+ dev_err(dev, "%s: Unable to read OPPs\n", __func__);
+ goto out;
+ }
+
+ if (nr % 2) {
+ dev_err(dev, "%s: Invalid OPP list\n", __func__);
+ ret = -EINVAL;
+ goto out;
+ }
+
+ nr /= 2;
+ for (i = 0; i < nr; i++) {
+ /*
+ * Each OPP is a set of tuples consisting of frequency and
+ * voltage like <freq-kHz vol-uV>.
+ */
+ u32 *val = opp + i * 2;
+
+ val[0] *= 1000;
+ ret = opp_add(dev, val[0], val[1]);
+ if (ret) {
+ dev_warn(dev, "%s: Failed to add OPP %d: %d\n",
+ __func__, val[0], ret);
+ continue;
+ }
+ }
+
+ ret = 0;
+out:
+ kfree(opp);
+ return ret;
+}
+#endif
diff --git a/include/linux/opp.h b/include/linux/opp.h
index 2a4e5fa..214e0eb 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)
{
--
1.7.5.4
--
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