On systems with multiple remote processors, the remoteproc device
enumeration is not stable as it depends on the probe ordering.
As a result, the /sys/class/remoteproc/remoteproc<x> entries do not
always refer to the same remote processor instance, which complicates
userspace applications.
Inspired by the SPI implementation, this commit allows board-specific
numbering to be defined in device tree while still supporting dynamically
registered remote processors.
For instance, on STM32MP25 Soc this can be used by defining:
aliases {
rproc0 = &m33_rproc;
rproc1 = &m0_rproc;
};
When a "rproc<x>" DT alias is present, use it to assign a fixed
"/sys/class/remoteproc/remoteproc<x>" entry.
If no remoteproc alias is defined, keep the legacy index allocation.
If only some remoteproc instances have an alias, allocate dynamic
index starting after the highest alias index declared.
Signed-off-by: Arnaud Pouliquen <[email protected]>
---
V2:
- Introduces rproc_get_index based on Mathieu Poirier's suggestion.
An update compared to Mathieu's version is that the call to
ida_alloc_range is retained if an alias is found for the remote device,
to balance with ida_free().
- Rename DT alias stem from "remoteproc" to "rproc" to be consistent with
keytone driver.
---
drivers/remoteproc/remoteproc_core.c | 40 ++++++++++++++++++++++++++--
include/linux/remoteproc.h | 3 +++
2 files changed, 41 insertions(+), 2 deletions(-)
diff --git a/drivers/remoteproc/remoteproc_core.c
b/drivers/remoteproc/remoteproc_core.c
index aada2780b343..38d6eb1c9483 100644
--- a/drivers/remoteproc/remoteproc_core.c
+++ b/drivers/remoteproc/remoteproc_core.c
@@ -2433,6 +2433,43 @@ static int rproc_alloc_ops(struct rproc *rproc, const
struct rproc_ops *ops)
return 0;
}
+/**
+ * rproc_get_index - assign a unique device index for a remote processor
+ * @dev: device associated with the remote processor
+ *
+ * Look for a static index coming from the "rproc" DT alias
+ * (e.g. "rproc0"). If none is found, start allocating
+ * dynamic IDs after the highest alias in use.
+ *
+ * Return: a non-negative index on success, or a negative error code on
failure.
+ */
+static int rproc_get_index(struct device *dev)
+{
+ int index;
+
+ /* No DT to deal with */
+ if (!dev->of_node)
+ goto legacy;
+
+ /* See if an alias has been assigned to this remoteproc */
+ index = of_alias_get_id(dev->of_node, RPROC_ALIAS);
+ if (index >= 0)
+ return ida_alloc_range(&rproc_dev_index, index, index,
+ GFP_KERNEL);
+ /*
+ * No alias has been assigned to this remoteproc device. See if any
+ * "rproc" aliases have been assigned and start allocating after
+ * the highest one if it is the case.
+ */
+ index = of_alias_get_highest_id(RPROC_ALIAS);
+ if (index >= 0)
+ return ida_alloc_range(&rproc_dev_index, index + 1, ~0,
+ GFP_KERNEL);
+
+legacy:
+ return ida_alloc(&rproc_dev_index, GFP_KERNEL);
+}
+
/**
* rproc_alloc() - allocate a remote processor handle
* @dev: the underlying device
@@ -2481,8 +2518,7 @@ struct rproc *rproc_alloc(struct device *dev, const char
*name,
rproc->dev.driver_data = rproc;
idr_init(&rproc->notifyids);
- /* Assign a unique device index and name */
- rproc->index = ida_alloc(&rproc_dev_index, GFP_KERNEL);
+ rproc->index = rproc_get_index(dev);
if (rproc->index < 0) {
dev_err(dev, "ida_alloc failed: %d\n", rproc->index);
goto put_device;
diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
index b4795698d8c2..3feb2456ecc4 100644
--- a/include/linux/remoteproc.h
+++ b/include/linux/remoteproc.h
@@ -503,6 +503,9 @@ enum rproc_features {
RPROC_MAX_FEATURES,
};
+ /* device tree remoteproc Alias stem */
+ #define RPROC_ALIAS "rproc"
+
/**
* struct rproc - represents a physical remote processor device
* @node: list node of this rproc object
--
2.43.0
