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Subject[PATCH v8 3/8] interconnect: Allow endpoints translation via DT
Date
Currently we support only platform data for specifying the interconnect
endpoints. As now the endpoints are hard-coded into the consumer driver
this may lead to complications when a single driver is used by multiple
SoCs, which may have different interconnect topology.
To avoid cluttering the consumer drivers, introduce a translation function
to help us get the board specific interconnect data from device-tree.

Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
Reviewed-by: Evan Green <evgreen@chromium.org>
---
drivers/interconnect/core.c | 78 ++++++++++++++++++++++++++++++++++++
include/linux/interconnect.h | 7 ++++
2 files changed, 85 insertions(+)

diff --git a/drivers/interconnect/core.c b/drivers/interconnect/core.c
index 9ca39aca4982..8f874d1b0a0f 100644
--- a/drivers/interconnect/core.c
+++ b/drivers/interconnect/core.c
@@ -15,6 +15,7 @@
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/slab.h>
+#include <linux/of.h>
#include <linux/overflow.h>

static DEFINE_IDR(icc_idr);
@@ -192,6 +193,83 @@ static int apply_constraints(struct icc_path *path)
return ret;
}

+/**
+ * of_icc_get() - get a path handle from a DT node based on name
+ * @dev: device pointer for the consumer device
+ * @name: interconnect path name
+ *
+ * This function will search for a path two endpoints and return an
+ * icc_path handle on success. Use icc_put() to release constraints when
+ * they are not needed anymore.
+ * If the interconnect API is disabled, NULL is returned and the consumer
+ * drivers will still build. Drivers are free to handle this specifically,
+ * but they don't have to. NULL is also returned when the "interconnects"
+ * DT property is missing.
+ *
+ * Return: icc_path pointer on success or ERR_PTR() on error. NULL is returned
+ * when the API is disabled or the "interconnects" DT property is missing.
+ */
+struct icc_path *of_icc_get(struct device *dev, const char *name)
+{
+ struct device_node *np = NULL;
+ struct of_phandle_args src_args, dst_args;
+ u32 src_id, dst_id;
+ int idx = 0;
+ int ret;
+
+ if (!dev || !dev->of_node)
+ return ERR_PTR(-ENODEV);
+
+ np = dev->of_node;
+
+ /*
+ * When the consumer DT node do not have "interconnects" property
+ * return a NULL path to skip setting constraints.
+ */
+ if (!of_find_property(np, "interconnects", NULL))
+ return NULL;
+
+ /*
+ * We use a combination of phandle and specifier for endpoint. For now
+ * lets support only global ids and extend this is the future if needed
+ * without breaking DT compatibility.
+ */
+ if (name) {
+ idx = of_property_match_string(np, "interconnect-names", name);
+ if (idx < 0)
+ return ERR_PTR(idx);
+ }
+
+ ret = of_parse_phandle_with_args(np, "interconnects",
+ "#interconnect-cells", idx * 2,
+ &src_args);
+ if (ret)
+ return ERR_PTR(ret);
+
+ of_node_put(src_args.np);
+
+ if (!src_args.args_count || src_args.args_count > 1)
+ return ERR_PTR(-EINVAL);
+
+ src_id = src_args.args[0];
+
+ ret = of_parse_phandle_with_args(np, "interconnects",
+ "#interconnect-cells", idx * 2 + 1,
+ &dst_args);
+ if (ret)
+ return ERR_PTR(ret);
+
+ of_node_put(dst_args.np);
+
+ if (!dst_args.args_count || dst_args.args_count > 1)
+ return ERR_PTR(-EINVAL);
+
+ dst_id = dst_args.args[0];
+
+ return icc_get(dev, src_id, dst_id);
+}
+EXPORT_SYMBOL_GPL(of_icc_get);
+
/**
* icc_set() - set constraints on an interconnect path between two endpoints
* @path: reference to the path returned by icc_get()
diff --git a/include/linux/interconnect.h b/include/linux/interconnect.h
index 593215371fd6..ae6744da9bc2 100644
--- a/include/linux/interconnect.h
+++ b/include/linux/interconnect.h
@@ -17,6 +17,7 @@ struct device;

struct icc_path *icc_get(struct device *dev, const int src_id,
const int dst_id);
+struct icc_path *of_icc_get(struct device *dev, const char *name);
void icc_put(struct icc_path *path);
int icc_set(struct icc_path *path, u32 avg_bw, u32 peak_bw);

@@ -28,6 +29,12 @@ static inline struct icc_path *icc_get(struct device *dev, const int src_id,
return NULL;
}

+static inline struct icc_path *of_icc_get(struct device *dev,
+ const char *name)
+{
+ return NULL;
+}
+
static inline void icc_put(struct icc_path *path)
{
}
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