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Subject[PATCH v11 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.

Reviewed-by: Evan Green <evgreen@chromium.org>
Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
---
drivers/interconnect/core.c | 149 ++++++++++++++++++++++++++
include/linux/interconnect-provider.h | 17 +++
include/linux/interconnect.h | 7 ++
3 files changed, 173 insertions(+)

diff --git a/drivers/interconnect/core.c b/drivers/interconnect/core.c
index 33d927758669..d1854dfb1bed 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);
@@ -194,6 +195,152 @@ static int apply_constraints(struct icc_path *path)
return ret;
}

+/* of_icc_xlate_onecell() - Translate function using a single index.
+ * @spec: OF phandle args to map into an interconnect node.
+ * @data: private data (pointer to struct icc_onecell_data)
+ *
+ * This is a generic translate function that can be used to model simple
+ * interconnect providers that have one device tree node and provide
+ * multiple interconnect nodes. A single cell is used as an index into
+ * an array of icc nodes specified in the icc_onecell_data struct when
+ * registering the provider.
+ */
+struct icc_node *of_icc_xlate_onecell(struct of_phandle_args *spec,
+ void *data)
+{
+ struct icc_onecell_data *icc_data = data;
+ unsigned int idx = spec->args[0];
+
+ if (idx >= icc_data->num_nodes) {
+ pr_err("%s: invalid index %u\n", __func__, idx);
+ return ERR_PTR(-EINVAL);
+ }
+
+ return icc_data->nodes[idx];
+}
+EXPORT_SYMBOL_GPL(of_icc_xlate_onecell);
+
+/**
+ * of_icc_get_from_provider() - Look-up interconnect node
+ * @spec: OF phandle args to use for look-up
+ *
+ * Looks for interconnect provider under the node specified by @spec and if
+ * found, uses xlate function of the provider to map phandle args to node.
+ *
+ * Returns a valid pointer to struct icc_node on success or ERR_PTR()
+ * on failure.
+ */
+static struct icc_node *of_icc_get_from_provider(struct of_phandle_args *spec)
+{
+ struct icc_node *node = ERR_PTR(-EPROBE_DEFER);
+ struct icc_provider *provider;
+
+ if (!spec || spec->args_count != 1)
+ return ERR_PTR(-EINVAL);
+
+ mutex_lock(&icc_lock);
+ list_for_each_entry(provider, &icc_providers, provider_list) {
+ if (provider->dev->of_node == spec->np)
+ node = provider->xlate(spec, provider->data);
+ if (!IS_ERR(node))
+ break;
+ }
+ mutex_unlock(&icc_lock);
+
+ return node;
+}
+
+/**
+ * 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 between 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.
+ *
+ * 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 icc_path *path = ERR_PTR(-EPROBE_DEFER);
+ struct icc_node *src_node, *dst_node;
+ struct device_node *np = NULL;
+ struct of_phandle_args src_args, dst_args;
+ 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 in 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);
+
+ 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);
+
+ src_node = of_icc_get_from_provider(&src_args);
+
+ if (IS_ERR(src_node)) {
+ if (PTR_ERR(src_node) != -EPROBE_DEFER)
+ dev_err(dev, "error finding src node: %ld\n",
+ PTR_ERR(src_node));
+ return ERR_CAST(src_node);
+ }
+
+ dst_node = of_icc_get_from_provider(&dst_args);
+
+ if (IS_ERR(dst_node)) {
+ if (PTR_ERR(dst_node) != -EPROBE_DEFER)
+ dev_err(dev, "error finding dst node: %ld\n",
+ PTR_ERR(dst_node));
+ return ERR_CAST(dst_node);
+ }
+
+ mutex_lock(&icc_lock);
+ path = path_find(dev, src_node, dst_node);
+ if (IS_ERR(path))
+ dev_err(dev, "%s: invalid path=%ld\n", __func__, PTR_ERR(path));
+ mutex_unlock(&icc_lock);
+
+ return path;
+}
+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()
@@ -519,6 +666,8 @@ int icc_provider_add(struct icc_provider *provider)
{
if (WARN_ON(!provider->set))
return -EINVAL;
+ if (WARN_ON(!provider->xlate))
+ return -EINVAL;

mutex_lock(&icc_lock);

diff --git a/include/linux/interconnect-provider.h b/include/linux/interconnect-provider.h
index 78208a754181..63caccadc2db 100644
--- a/include/linux/interconnect-provider.h
+++ b/include/linux/interconnect-provider.h
@@ -12,6 +12,21 @@
#define icc_units_to_bps(bw) ((bw) * 1000ULL)

struct icc_node;
+struct of_phandle_args;
+
+/**
+ * struct icc_onecell_data - driver data for onecell interconnect providers
+ *
+ * @num_nodes: number of nodes in this device
+ * @nodes: array of pointers to the nodes in this device
+ */
+struct icc_onecell_data {
+ unsigned int num_nodes;
+ struct icc_node *nodes[];
+};
+
+struct icc_node *of_icc_xlate_onecell(struct of_phandle_args *spec,
+ void *data);

/**
* struct icc_provider - interconnect provider (controller) entity that might
@@ -21,6 +36,7 @@ struct icc_node;
* @nodes: internal list of the interconnect provider nodes
* @set: pointer to device specific set operation function
* @aggregate: pointer to device specific aggregate operation function
+ * @xlate: provider-specific callback for mapping nodes from phandle arguments
* @dev: the device this interconnect provider belongs to
* @users: count of active users
* @data: pointer to private data
@@ -31,6 +47,7 @@ struct icc_provider {
int (*set)(struct icc_node *src, struct icc_node *dst);
int (*aggregate)(struct icc_node *node, u32 avg_bw, u32 peak_bw,
u32 *agg_avg, u32 *agg_peak);
+ struct icc_node* (*xlate)(struct of_phandle_args *spec, void *data);
struct device *dev;
int users;
void *data;
diff --git a/include/linux/interconnect.h b/include/linux/interconnect.h
index 348957c6d767..8d4b0009b788 100644
--- a/include/linux/interconnect.h
+++ b/include/linux/interconnect.h
@@ -27,6 +27,7 @@ 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);

@@ -38,6 +39,12 @@ 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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